167 results on '"Crista"'
Search Results
2. Erratum: Dopaminergic Inhibition of Na+ Currents in Vestibular Inner Ear Afferents
- Author
-
Frontiers Production Office
- Subjects
calyx ,semicircular canal ,crista ,hair cell ,sodium channel ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Published
- 2022
- Full Text
- View/download PDF
3. Dopaminergic Inhibition of Na+ Currents in Vestibular Inner Ear Afferents.
- Author
-
Meredith, Frances L. and Rennie, Katherine J.
- Subjects
AFFERENT pathways ,INNER ear ,DOPAMINE ,CENTRAL nervous system ,HAIR cells ,AUDITORY pathways - Abstract
Inner ear hair cells form synapses with afferent terminals and afferent neurons carry signals as action potentials to the central nervous system. Efferent neurons have their origins in the brainstem and some make synaptic contact with afferent dendrites beneath hair cells. Several neurotransmitters have been identified that may be released from efferent terminals to modulate afferent activity. Dopamine is a candidate efferent neurotransmitter in both the vestibular and auditory systems. Within the cochlea, activation of dopamine receptors may reduce excitotoxicity at the inner hair cell synapse via a direct effect of dopamine on afferent terminals. Here we investigated the effect of dopamine on sodium currents in acutely dissociated vestibular afferent calyces to determine if dopaminergic signaling could also modulate vestibular responses. Calyx terminals were isolated along with their accompanying type I hair cells from the cristae of gerbils (P15-33) and whole cell patch clamp recordings performed. Large transient sodium currents were present in all isolated calyces; compared to data from crista slices, resurgent Na
+ currents were rare. Perfusion of dopamine (100 μM) in the extracellular solution significantly reduced peak transient Na+ currents by approximately 20% of control. A decrease in Na+ current amplitude was also seen with extracellular application of the D2 dopamine receptor agonist quinpirole, whereas the D2 receptor antagonist eticlopride largely abolished the response to dopamine. Inclusion of the phosphatase inhibitor okadaic acid in the patch electrode solution occluded the response to dopamine. The reduction in calyx sodium current in response to dopamine suggests efferent signaling through D2 dopaminergic receptors may occur via common mechanisms to decrease excitability in inner ear afferents. [ABSTRACT FROM AUTHOR]- Published
- 2021
- Full Text
- View/download PDF
4. Repurposing disulfiram to induce OSCC cell death by cristae dysfunction promoted autophagy.
- Author
-
Wang, Zhen, Jiang, Han, Cai, Lu‐Yao, Ji, Ning, Zeng, Xin, Zhou, Yu, Shen, Ying‐Qiang, and Chen, Qian‐Ming
- Subjects
- *
ADENOSINE triphosphate metabolism , *MOUTH tumors , *AUTOPHAGY , *PHOSPHOTRANSFERASES , *ANIMAL experimentation , *MITOCHONDRIA , *CELLULAR signal transduction , *DISULFIRAM , *CELL proliferation , *RESPIRATION , *SQUAMOUS cell carcinoma , *CELL death , *MICE - Abstract
Objective: Disulfiram has been repurposed as a potential candidate to suppress various cancers. However, its anti‐tumor effects and molecular mechanisms of oral squamous cell carcinoma remain unclear. In this study, we aimed to assess the anti‐cancer activity and underlying mechanisms of disulfiram in the context of oral squamous cell carcinoma. Materials and Methods: We tested the cytotoxicity of disulfiram in oral squamous cell carcinoma using a 3D culture model and a PDX model. Cell proliferation, cell death, and related signaling pathways were evaluated. Mitochondrial DNA copy number, mitochondrial respiration, mitochondrial mass, and mitochondrial complexes were analyzed. Results: Disulfiram can induce excessive autophagy in oral squamous cell carcinoma cells as a result of OXPHOS deficiency. Disulfiram‐induced OPA1 degradation can impair the functional cristae structure, which results in a dramatic reduction in mitochondrial respiration capability as well as ATP production. Subsequently, energy deprivation leads to excessive autophagy through AMPK activation. In addition, exogenous ATP blocked the activation of AMPK and rescued disulfiram‐induced cell death. Conclusion: DSF targets mitochondrial inner membrane protein OPA1 to disturb the energy supply, triggering excessive autophagy, and cell death in OSCC. Our study suggests OPA1‐dependent ATP generation is pharmacologically targetable in OSCC treatment. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
5. Dopaminergic Inhibition of Na+ Currents in Vestibular Inner Ear Afferents
- Author
-
Frances L. Meredith and Katherine J. Rennie
- Subjects
calyx ,semicircular canal ,crista ,hair cell ,sodium channel ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
Inner ear hair cells form synapses with afferent terminals and afferent neurons carry signals as action potentials to the central nervous system. Efferent neurons have their origins in the brainstem and some make synaptic contact with afferent dendrites beneath hair cells. Several neurotransmitters have been identified that may be released from efferent terminals to modulate afferent activity. Dopamine is a candidate efferent neurotransmitter in both the vestibular and auditory systems. Within the cochlea, activation of dopamine receptors may reduce excitotoxicity at the inner hair cell synapse via a direct effect of dopamine on afferent terminals. Here we investigated the effect of dopamine on sodium currents in acutely dissociated vestibular afferent calyces to determine if dopaminergic signaling could also modulate vestibular responses. Calyx terminals were isolated along with their accompanying type I hair cells from the cristae of gerbils (P15-33) and whole cell patch clamp recordings performed. Large transient sodium currents were present in all isolated calyces; compared to data from crista slices, resurgent Na+ currents were rare. Perfusion of dopamine (100 μM) in the extracellular solution significantly reduced peak transient Na+ currents by approximately 20% of control. A decrease in Na+ current amplitude was also seen with extracellular application of the D2 dopamine receptor agonist quinpirole, whereas the D2 receptor antagonist eticlopride largely abolished the response to dopamine. Inclusion of the phosphatase inhibitor okadaic acid in the patch electrode solution occluded the response to dopamine. The reduction in calyx sodium current in response to dopamine suggests efferent signaling through D2 dopaminergic receptors may occur via common mechanisms to decrease excitability in inner ear afferents.
- Published
- 2021
- Full Text
- View/download PDF
6. Translations of Steinhausen's Publications Provide Insight Into Their Contributions to Peripheral Vestibular Neuroscience
- Author
-
Hans Straka, Michael G. Paulin, and Larry F. Hoffman
- Subjects
cupula ,endolymph ,biomechanical model ,crista ,labyrinth ,torsion-pendulum ,Neurology. Diseases of the nervous system ,RC346-429 - Abstract
The quantitative relationship between angular head movement and semicircular canal function is most often referenced to the well-known torsion-pendulum model that predicts cupular displacement from input head acceleration. The foundation of this model can be traced back to Steinhausen's series of papers between 1927 and 1933 whereby he endeavored to document observations of cupular displacements that would directly infer movement of the endolymph resulting from angular rotation. He also was the first to establish the direct relationship between cupular displacement and compensatory eye movements. While the chronology of these findings, with their successes and pitfalls, are documented in Steinhausen's work, it reflects a fascinating journey that has been inaccessible to the non-German speaking community. Therefore, the present compilation of translations, with accompanying introduction and discussion, was undertaken to allow a larger component of the vestibular scientific community to gain insight into peripheral labyrinthine mechanics provided by this historical account.
- Published
- 2021
- Full Text
- View/download PDF
7. Translations of Steinhausen's Publications Provide Insight Into Their Contributions to Peripheral Vestibular Neuroscience.
- Author
-
Straka, Hans, Paulin, Michael G., Hoffman, Larry F., and Steinhausen, Wilhelm
- Subjects
TRANSLATING & interpreting ,SEMICIRCULAR canals ,NEUROSCIENCES ,EYE movements ,SCIENTIFIC community - Abstract
The quantitative relationship between angular head movement and semicircular canal function is most often referenced to the well-known torsion-pendulum model that predicts cupular displacement from input head acceleration. The foundation of this model can be traced back to Steinhausen's series of papers between 1927 and 1933 whereby he endeavored to document observations of cupular displacements that would directly infer movement of the endolymph resulting from angular rotation. He also was the first to establish the direct relationship between cupular displacement and compensatory eye movements. While the chronology of these findings, with their successes and pitfalls, are documented in Steinhausen's work, it reflects a fascinating journey that has been inaccessible to the non-German speaking community. Therefore, the present compilation of translations, with accompanying introduction and discussion, was undertaken to allow a larger component of the vestibular scientific community to gain insight into peripheral labyrinthine mechanics provided by this historical account. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
8. Nestin-expressing cells are mitotically active in the mammalian inner ear.
- Author
-
Kalmanson, Olivia, Takeda, Hiroki, Anderson, Sean R., Dondzillo, Anna, and Gubbels, Samuel
- Subjects
- *
INNER ear , *CORTI'S organ , *HAIR cells , *PROGENITOR cells , *NESTIN - Abstract
• Nestin is associated with pluripotency and is expressed in the inner ear. • A lineage-tracing model tracked nestin-expressing cells in early postnatal mice. • Nestin-expressing cells are mitotically active in cochlear and vestibular tissues. • Nestin-expressing cells did not facilitate hair cell regeneration after ablation. • Further research into the mitotic activity of nestin-expressing cells is warranted. Nestin expression is associated with pluripotency. Growing evidence suggests nestin is involved in hair cell development. The objective of this study was to investigate the morphology and role of nestin-expressing cells residing in the early postnatal murine inner ear. A lineage-tracing nestin reporter mouse line was used to further characterize these cells. Their cochleae and vestibular organs were immunostained and whole-mounted for cell counting. We found Nestin-expressing cells present in low numbers throughout the inner ear. Three morphotypes were observed: bipolar, unipolar, and globular. Mitotic activity was noted in nestin-expressing cells in the cochlea, utricle, saccule, and crista. Nestin-expressing cell characteristics were then observed after hair cell ablation in two mouse models. First, a reporter model demonstrated nestin expression in a significantly higher proportion of hair cells after hair cell ablation than in control cochleae. However, in a lineage tracing nestin reporter mouse, none of the new hair cells which repopulated the organ of Corti after hair cell ablation expressed nestin, nor did the nestin-expressing cells change in morphotype. In conclusion, Nestin-expressing cells were identified in the cochlea and vestibular organs. After hair cell ablation, nestin-expressing cells did not react to the insult. However, a small number of nestin-expressing cells in all inner ear tissues exhibited mitotic activity, supporting progenitor cell potential, though perhaps not involved in hair cell regeneration. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
9. Persistent and resurgent Na+ currents in vestibular calyx afferents.
- Author
-
Meredith, Frances L. and Rennie, Katherine J.
- Abstract
Vestibular afferent neurons convey information from hair cells in the peripheral vestibular end organs to central nuclei. Primary vestibular afferent neurons can fire action potentials at high rates and afferent firing patterns vary with the position of nerve terminal endings in vestibular neuroepithelia. Terminals contact hair cells as small bouton or large calyx endings. To investigate the role of Na+ currents (INa) in firing mechanisms, we investigated biophysical properties of INa in calyx-bearing afferents. Whole cell patch-clamp recordings were made from calyx terminals in thin slices of gerbil crista at different postnatal ages: immature [postnatal day (P)5-P8, young (P13-P15), and mature (P30-P45)]. A large transient Na+ current (INaT) was completely blocked by 300 nM tetrodotoxin (TTX) in mature calyces. In addition, INaT was accompanied by much smaller persistent Na+ currents (INaP) and distinctive resurgent Na+ currents (INaR), which were also blocked by TTX. ATX-II, a toxin that slows Na+ channel inactivation, enhanced INaP in immature and mature calyces. 4,9-Anhydro-TTX (4,9-ah-TTX), which selectively blocks Nav1.6 channels, abolished the enhanced INa in mature, but not immature, calyces. Therefore, Nav1.6 channels mediate a component of INaT and INaP in mature calyces, but are minimally expressed at early postnatal days. INaR was expressed in less than one-third of calyces at P6-P8, but expression increased with development, and in mature cristae INaR was frequently found in peripheral calyces. INaR served to increase the availability of Na+ channels following brief membrane depolarizations. In current clamp, the rate and regularity of action potential firing decreased in mature peripheral calyces following 4,9-ah-TTX application. Therefore, Nav1.6 channels are upregulated during development, contribute to INaT, INaP, and INaR, and may regulate excitability by enabling higher mean discharge rates in a subpopulation of mature calyx afferents. NEW & NOTEWORTHY Action potential firing patterns differ between groups of afferent neurons innervating vestibular epithelia. We investigated the biophysical properties of Na+ currents in specialized vestibular calyx afferent terminals during postnatal development. Mature calyces express Na+ currents with transient, persistent, and resurgent components. Nav1.6 channels contribute to resurgent Na+ currents and may enhance firing in peripheral calyx afferents. Understanding Na+ channels that contribute to vestibular nerve responses has implications for developing new treatments for vestibular dysfunction. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
10. Calbindin expression in adult vestibular epithelia.
- Author
-
Prins, Terry J., Myers, Zachary A., Saldate, Johnny J., and Hoffman, Larry F.
- Subjects
- *
CALBINDIN , *CALCIUM-binding proteins , *CALRETININ , *HAIR cells , *CELL polarity - Abstract
The mammalian vestibular epithelia exhibit a remarkably stereotyped organization featuring cellular characteristics under planar cell polarity (PCP) control. PCP mechanisms are responsible for the organization of hair cell morphologic polarization vectors, and are thought to be responsible for the postsynaptic expression of the calcium-binding protein calretinin that defines the utricular striola and cristae central zone. However, recent analyses revealed that subtle differences in the topographic expression of oncomodulin, another calcium-binding protein, reflects heterogeneous factors driving the subtle variations in expression. Calbindin represents a third calcium-binding protein that has been previously described to be expressed in both hair cells and afferent calyces in proximity to the utricular striola and crista central zone. The objective of the present investigation was to determine calbindin's topographic pattern of expression to further elucidate the extent to which PCP mechanisms might exert control over the organization of vestibular neuroepithelia. The findings revealed that calbindin exhibited an expression pattern strikingly similar to oncomodulin. However, within calyces of the central zone calbindin was colocalized with calretinin. These results indicate that organizational features of vestibular epithelia are governed by a suite of factors that include PCP mechanisms as well others yet to be defined. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
11. Interaction with ectopic cochlear crista sensory epithelium disrupts basal cochlear sensory epithelium development in Lmx1a mutant mice.
- Author
-
Nichols, David H., Bouma, Judith E., Kopecky, Benjamin J., Jahan, Israt, Beisel, Kirk W., He, David Z. Z., Liu, Huizhan, and Fritzsch, Bernd
- Subjects
- *
HAIR cells , *COCHLEA physiology , *COCHLEAR nucleus , *EPITHELIUM , *CORTI'S organ - Abstract
The LIM homeodomain transcription factor Lmx1a shows a dynamic expression in the developing mouse ear that stabilizes in the non-sensory epithelium. Previous work showed that Lmx1a functional null mutants have an additional sensory hair cell patch in the posterior wall of a cochlear duct and have a mix of vestibular and cochlear hair cells in the basal cochlear sensory epithelium. In E13.5 mutants, Sox2-expressing posterior canal crista is continuous with an ectopic "crista sensory epithelium" located in the outer spiral sulcus of the basal cochlear duct. The medial margin of cochlear crista is in contact with the adjacent Sox2-expressing basal cochlear sensory epithelium. By E17.5, this contact has been interrupted by the formation of an intervening non-sensory epithelium, and Atoh1 is expressed in the hair cells of both the cochlear crista and the basal cochlear sensory epithelium. Where cochlear crista was formerly associated with the basal cochlear sensory epithelium, the basal cochlear sensory epithelium lacks an outer hair cell band, and gaps are present in its associated Bmp4 expression. Further apically, where cochlear crista was never present, the cochlear sensory epithelium forms a poorly ordered but complete organ of Corti. We propose that the core prosensory posterior crista is enlarged in the mutant when the absence of Lmx1a expression allows JAG1-NOTCH signaling to propagate into the adjacent epithelium and down the posterior wall of the cochlear duct. We suggest that the cochlear crista propagates in the mutant outer spiral sulcus because it expresses Lmo4 in the absence of Lmx1a. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
12. Regional and Developmental Differences in Na+ Currents in Vestibular Primary Afferent Neurons
- Author
-
Frances L. Meredith and Katherine J. Rennie
- Subjects
calyx ,semicircular canal ,crista ,4,9-anhydrotetrodotoxin ,tetrodotoxin ,Na+ channel ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
The vestibular system relays information about head position via afferent nerve fibers to the brain in the form of action potentials. Voltage-gated Na+ channels in vestibular afferents drive the initiation and propagation of action potentials, but their expression during postnatal development and their contributions to firing in diverse mature afferent populations are unknown. Electrophysiological techniques were used to determine Na+ channel subunit types in vestibular calyx-bearing afferents at different stages of postnatal development. We used whole cell patch clamp recordings in thin slices of gerbil crista neuroepithelium to investigate Na+ channels and firing patterns in central zone (CZ) and peripheral zone (PZ) afferents. PZ afferents are exclusively dimorphic, innervating type I and type II hair cells, whereas CZ afferents can form dimorphs or calyx-only terminals which innervate type I hair cells alone. All afferents expressed tetrodotoxin (TTX)-sensitive Na+ currents, but TTX-sensitivity varied with age. During the fourth postnatal week, 200–300 nM TTX completely blocked sodium currents in PZ and CZ calyces. By contrast, in immature calyces [postnatal day (P) 5–11], a small component of peak sodium current remained in 200 nM TTX. Application of 1 μM TTX, or Jingzhaotoxin-III plus 200 nM TTX, abolished sodium current in immature calyces, suggesting the transient expression of voltage-gated sodium channel 1.5 (Nav1.5) during development. A similar TTX-insensitive current was found in early postnatal crista hair cells (P5–9) and constituted approximately one third of the total sodium current. The Nav1.6 channel blocker, 4,9-anhydrotetrodotoxin, reduced a component of sodium current in immature and mature calyces. At 100 nM 4,9-anhydrotetrodotoxin, peak sodium current was reduced on average by 20% in P5–14 calyces, by 37% in mature dimorphic PZ calyces, but by less than 15% in mature CZ calyx-only terminals. In mature PZ calyces, action potentials became shorter and broader in the presence of 4,9-anhydrotetrodotoxin implicating a role for Nav1.6 channels in firing in dimorphic afferents.
- Published
- 2018
- Full Text
- View/download PDF
13. Regional and Developmental Differences in Na+ Currents in Vestibular Primary Afferent Neurons.
- Author
-
Meredith, Frances L. and Rennie, Katherine J.
- Abstract
The vestibular system relays information about head position via afferent nerve fibers to the brain in the form of action potentials. Voltage-gated Na
+ channels in vestibular afferents drive the initiation and propagation of action potentials, but their expression during postnatal development and their contributions to firing in diverse mature afferent populations are unknown. Electrophysiological techniques were used to determine Na+ channel subunit types in vestibular calyx-bearing afferents at different stages of postnatal development. We used whole cell patch clamp recordings in thin slices of gerbil crista neuroepithelium to investigate Na+ channels and firing patterns in central zone (CZ) and peripheral zone (PZ) afferents. PZ afferents are exclusively dimorphic, innervating type I and type II hair cells, whereas CZ afferents can form dimorphs or calyx-only terminals which innervate type I hair cells alone. All afferents expressed tetrodotoxin (TTX)-sensitive Na+ currents, but TTX-sensitivity varied with age. During the fourth postnatal week, 200–300 nM TTX completely blocked sodium currents in PZ and CZ calyces. By contrast, in immature calyces [postnatal day (P) 5–11], a small component of peak sodium current remained in 200 nM TTX. Application of 1 μM TTX, or Jingzhaotoxin-III plus 200 nM TTX, abolished sodium current in immature calyces, suggesting the transient expression of voltage-gated sodium channel 1.5 (Nav1.5) during development. A similar TTX-insensitive current was found in early postnatal crista hair cells (P5–9) and constituted approximately one third of the total sodium current. The Nav1.6 channel blocker, 4,9-anhydrotetrodotoxin, reduced a component of sodium current in immature and mature calyces. At 100 nM 4,9-anhydrotetrodotoxin, peak sodium current was reduced on average by 20% in P5–14 calyces, by 37% in mature dimorphic PZ calyces, but by less than 15% in mature CZ calyx-only terminals. In mature PZ calyces, action potentials became shorter and broader in the presence of 4,9-anhydrotetrodotoxin implicating a role for Nav1.6 channels in firing in dimorphic afferents. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
14. Sperm-associated antigen 6 (Spag6) mutation leads to vestibular dysfunction in mice
- Author
-
Haibo Wang, Daogong Zhang, Na Zhang, Lei Xu, Zhibing Zhang, Jerome F. Strauss, Wenwen Liu, and Xiaofei Li
- Subjects
Axoneme ,Male ,Stereocilia (inner ear) ,Mice, Transgenic ,Apoptosis ,RM1-950 ,Biology ,Vestibular Nerve ,Hair cells ,Hair Cells, Vestibular ,Hearing ,medicine ,otorhinolaryngologic diseases ,Animals ,Inner ear ,Vestibular dysfunction ,Sperm-associated antigen 6 ,Cochlea ,Vestibular Hair Cell ,Pharmacology ,Vestibular system ,Cell Polarity ,Scarpa's ganglion cells ,Cell biology ,Crista ,medicine.anatomical_structure ,Vestibular Diseases ,Vestibule ,Mutation ,Microtubule Proteins ,Molecular Medicine ,Female ,sense organs ,Therapeutics. Pharmacology - Abstract
Spag6 encodes an axoneme central apparatus protein that is required for normal flagellar and cilia motility. Recent findings suggest that Spag6 plays a role in hearing and planar cell polarity (PCP) in the cochlea of the inner ear. However, a role for Spag6 in the vestibule has not yet been explored. In the present study, the function of Spag6 in the vestibule of the inner ear was examined using Spag6-deficient mice. Our results demonstrate a vestibular disorder in the Spag6 mutants, associated with abnormal ultrastructures of vestibular hair cells and Scarpa's ganglion cells, including swollen stereocilia, decreased crista in mitochondria and swollen Scarpa's ganglion cells. Immunostaining data suggests existence of caspase-dependent apoptosis in vestibular sensory epithelium and Scarpa's ganglion cells. Our observations reveal new functions for Spag6 in vestibular function and apoptosis in the mouse vestibule.
- Published
- 2021
15. Comb, cloaca and feet scores and testis morphometry in male broiler breeders at two different ages.
- Author
-
Leão, R. A. C., Castro, F. L. S., Xavier, P. R., Vaz, D. P., Grázia, J. G. V., Baião, N. C., Avelar, G. F., and Júnior, A. P. Marques
- Abstract
Copyright of Arquivo Brasileiro de Medicina Veterinaria e Zootecnia is the property of Universidade Federal de Minas Gerais, Escola de Veterinaria and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2017
- Full Text
- View/download PDF
16. 'Quando sahir de caza, arme-te com o signal da Cruz': instruções para a rotina de um menino cristão em um manual pedagógico português do século XVIII
- Author
-
Giana Lange do Amaral and Fernando Cezar Ripe
- Subjects
Cristã ,Infância ,Literatura de Comportamento Social ,Século XVIII ,History (General) ,D1-2009 - Abstract
Este artigo tem por objetivo analisar certos enunciados religiosos para o cotidiano da infância masculina presentes no manual pedagógico Escola Nova, Christã, e Politica, Na qual se ensinão os primeiros rudimentos, que deve saber o Menino Christão, e se lhes dão regras para com facilidade, e em pouco tempo aprender a ler, escrever e contar. Publicada em Portugal inicialmente no ano de 1756 a obra de autoria de Francisco Luiz Ameno (1713-1793) foi registrada pelo pseudônimo de D. Leonor Thomasia de Sousa e Silva. Ao enquadrar o manual na categoria de Literatura de Comportamento Social, interessa-me, em particular, verificar as instruções que o autor prescreveu para a rotina de um menino cristão no contexto setecentista português. Nesse sentido, o conjunto das práticas recomendadas foram percebidas, aqui como mecanismos para a produção de máximas morais e de comportamentos socialmente desejáveis, que constituíram modos específicos de ser menino infantil em Portugal no século XVIII.
- Published
- 2017
- Full Text
- View/download PDF
17. Escores de cloaca e de crista e morfometria testicular em galos de matriz pesada com 71 semanas de idade e três categorias de peso corporal
- Author
-
C.A. Rezende, N.C. Baião, L.E.A. Ruiz, P.R. Xavier, and A.P. Marques Júnior
- Subjects
galo ,cloaca ,crista ,testículos ,peso ,Animal culture ,SF1-1100 - Abstract
Em galos de matriz pesada, o peso dos testículos se associa positivamente com a produção diária de espermatozoides e com a fertilidade. Contudo, os testículos de aves se localizam na cavidade abdominal, não sendo acessíveis para exame andrológico como os testículos de mamíferos. A avaliação reprodutiva de galos de matriz pesada é subjetiva e se baseia em características como peso corporal (PC), qualidade de pés e pernas e morfologia de cloaca e crista. Estudos que validem o potencial de associação dessas características fenotípicas com parâmetros da morfometria testicular são raros, principalmente quando se consideram galos de matriz pesada manejados em lotes comerciais. Escores de cloaca e de crista e parâmetros da morfometria testicular foram avaliados em galos Cobb 500 Slow adultos das categorias de PC leve (
- Published
- 2014
- Full Text
- View/download PDF
18. Effect of crista morphology on mitochondrial ATP output: A computational study
- Author
-
M. Saleet Jafri, Nasrin Afzal, Carmen A. Mannella, and W. Jonathan Lederer
- Subjects
ATP synthesis ,ATP synthase ,biology ,Chemistry ,Kinase ,Physiology ,Adenylate kinase ,Specialties of internal medicine ,Computational modeling ,Kinases ,General Medicine ,Energy metabolism ,Mitochondrion ,Article ,Mitochondria ,Cristae ,Crista ,Cytosol ,RC581-951 ,biology.protein ,Biophysics ,Inner membrane ,QP1-981 ,Inner mitochondrial membrane - Abstract
Folding of the mitochondrial inner membrane (IM) into cristae greatly increases the ATP-generating surface area, SIM, per unit volume but also creates diffusional bottlenecks that could limit reaction rates inside mitochondria. This study explores possible effects of inner membrane folding on mitochondrial ATP output, using a mathematical model for energy metabolism developed by the Jafri group and two- and three-dimensional spatial models for mitochondria, implemented on the Virtual Cell platform. Simulations demonstrate that cristae are micro-compartments functionally distinct from the cytosol. At physiological steady states, standing gradients of ADP form inside cristae that depend on the size and shape of the compartments, and reduce local flux (rate per unit area) of the adenine nucleotide translocase. This causes matrix ADP levels to drop, which in turn reduces the flux of ATP synthase. The adverse effects of membrane folding on reaction fluxes increase with crista length and are greater for lamellar than tubular crista. However, total ATP output per mitochondrion is the product of flux of ATP synthase and SIM which can be two-fold greater for mitochondria with lamellar than tubular cristae, resulting in greater ATP output for the former. The simulations also demonstrate the crucial role played by intracristal kinases (adenylate kinase, creatine kinase) in maintaining the energy advantage of IM folding.
- Published
- 2021
19. Cellular adaptations in the crista epithelia of the Egyptian fruit bat
- Author
-
Ton, Ymi
- Subjects
Physiology ,Ampullaris ,Bat ,Crista ,Egyptian ,Rousettus ,Vestibular - Abstract
We believe that the flight and echolocation behaviors displayed by the Egyptian fruit bat (Rousettus aegyptiacus) may translate to more precise head movement coding in response to their unique sensorimotor demands. While there is evidence for a relationship between locomotive behaviors and structural adaptations in the bony labyrinth of birds and mammals, none exist in the bat’s bony labyrinth. The present study determines whether cellular adaptations that translate to increased capability for high fidelity head movement coding exist in the crista central zone of Rousettus. This was accomplished using immunohistochemical techniques comparing hair cell and afferent phenotypes within crista central zone of Rousettus and the mouse (Mus musculus). Central zone hair cell counts revealed an increased fraction of type I hair cells in Rousettus. Additionally, Rousettus exhibits increases in the proportion of higher order complex calyces within the central zone. The calcium binding protein OCM is also observed to have expression that is restricted to type I hair cells in the central zone of Rousettus, unlike in Mus where it is also expressed in type II hair cells. KCNQ4, a low-voltage activated potassium channel, exhibits a positive association with CALB2 expression in the central zone of both Rousettus and Mus, which suggests that their association may contribute to the unique response characteristics of calyx-only afferents that project to the central zone. These findings provide evidence that the crista epithelia of Rousettus exhibits cellular adaptations that are consistent with enhanced head movement coding that may serve to be advantageous to their unique behavioral niche.
- Published
- 2017
20. AMPA receptor-mediated rapid EPSCs in vestibular calyx afferents.
- Author
-
Kirk, Matthew E., Meredith, Frances L., Benke, Timothy A., and Rennie, Katherine J.
- Subjects
- *
AMPA receptors , *EXCITATORY postsynaptic potential , *VESTIBULAR stimulation , *AFFERENT pathways , *NEURAL transmission , *HAIR cells - Abstract
In the vestibular periphery neurotransmission between hair cells and primary afferent nerves occurs via specialized ribbon synapses. Type I vestibular hair cells (HCIs) make synaptic contacts with calyx terminals, which enclose most of the HCI basolateral surface. To probe synaptic transmission, whole cell patchclamp recordings were made from calyx afferent terminals isolated together with their mature HCIs from gerbil crista. Neurotransmitter release was measured as excitatory postsynaptic currents (EPSCs) in voltage clamp. Spontaneous EPSCs were classified as simple or complex. Simple events exhibited a rapid rise time and a fast mono-exponential decay (time constant < 1 ms). The remaining events, constituting ~40% of EPSCs, showed more complex characteristics. Extracellular Sr²⁺ greatly increased EPSC frequency, and EPSCs were blocked by the AMPA receptor blocker NBQX. The role of presynaptic Ca²⁺ channels was assessed by application of the L-type Ca²⁺ channel blocker nifedipine (20 µM), which reduced EPSC frequency. In contrast, the L-type Ca²⁺ channel opener BAY K 8644 increased EPSC frequency. Cyclothiazide increased the decay time constant of averaged simple EPSCs by approximately twofold. The low-affinity AMPA receptor antagonist γ-D-glutamylglycine (2 mM) reduced the proportion of simple EPSCs relative to complex events, indicating glutamate accumulation in the restricted cleft between HCI and calyx. In crista slices EPSC frequency was greater in central compared with peripheral calyces, which may be due to greater numbers of presynaptic ribbons in central hair cells. Our data support a role for L-type Ca²⁺ channels in spontaneous release and demonstrate regional variations in AMPA-mediated quantal transmission at the calyx synapse. NEW & NOTEWORTHY In vestibular calyx terminals of mature cristae we find that the majority of excitatory postsynaptic currents (EPSCs) are rapid monophasic events mediated by AMPA receptors. Spontaneous EPSCs are reduced by an L-type Ca²⁺ channel blocker and notably enhanced in extracellular Sr²⁺. EPSC frequency is greater in central areas of the crista compared with peripheral areas and may be associated with more numerous presynaptic ribbons in central hair cells. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
21. Peripheral vestibular pathology in Mondini dysplasia.
- Author
-
Kaya, Serdar, Hızlı, Ömer, Kaya, Fatıma Kübra, Monsanto, Rafael DaCosta, Paparella, Michael M., and Cureoglu, Sebahattin
- Abstract
Objectives/hypothesis: In this study, our objective was to histopathologically analyze the peripheral vestibular system in patients with Mondini dysplasia.Study Design: Comparative human temporal bone study.Methods: We assessed the sensory epithelium of the human vestibular system with a focus on the number of type I and type II hair cells, as well as the total number of hair cells. We compared those numbers in our Mondini dysplasia group versus our control group.Results: The loss of type I and type II hair cells in the cristae of the superior, lateral, and posterior semicircular canals, as well as in the saccular and utricular macula, was significantly higher in our Mondini dysplasia group than in our control group. The total number of hair cells significantly decreased in the cristae of the superior, lateral, and posterior semicircular canals, as well as in the saccular and utricular macula, in our Mondini dysplasia group.Conclusion: Loss of vestibular hair cells can lead to vestibular dysfunction in patients with Mondini dysplasia.Level Of Evidence: NA Laryngoscope, 127:206-209, 2017. [ABSTRACT FROM AUTHOR]- Published
- 2017
- Full Text
- View/download PDF
22. Genome-Wide Association Analysis Identifies Dcc as an Essential Factor in the Innervation of the Peripheral Vestibular System in Inbred Mice.
- Author
-
Salehi, Pezhman, Myint, Anthony, Kim, Young, Ge, Marshall, Lavinsky, Joel, Ho, Maria, Crow, Amanda, Cruz, Charlene, Monges-Hernadez, Maya, Wang, Juemei, Hartiala, Jaana, Zhang, Li, Allayee, Hooman, Lusis, Aldons, Ohyama, Takahiro, Friedman, Rick, Kim, Young J, Ge, Marshall X, Ho, Maria K, and Crow, Amanda L
- Abstract
This study aimed to investigate the genetic causes of vestibular dysfunction. We used vestibular sensory-evoked potentials (VsEPs) to characterize the vestibular function of 35 inbred mouse strains selected from the Hybrid Mouse Diversity Panel and demonstrated strain-dependent phenotypic variation in vestibular function. Using these phenotypic data, we performed the first genome-wide association study controlling for population structure that has revealed two highly suggestive loci, one of which lies within a haplotype block containing five genes (Stard6, 4930503L19Rik, Poli, Mbd2, Dcc) on Chr. 18 (peak SNP rs29632020), one gene, deleted in colorectal carcinoma (Dcc) has a well-established role in nervous system development. An in-depth analysis of Dcc-deficient mice demonstrated elevation in mean VsEP threshold for Dcc (+/-) mice (-11.86 dB) compared to wild-type (-9.68 dB) littermates. Synaptic ribbon studies revealed Dcc (-/-) (P0) and Dcc (+/-) (6-week-old) mice showed lower density of the presynaptic marker (CtBP2) as compared to wild-type controls. Vestibular ganglion cell counts of Dcc (-/-) (P0) was lower than controls. Whole-mount preparations showed abnormal innervation of the utricle, saccule, and crista ampullaris at E14.5, E16.5, and E18.5. Postnatal studies were limited by the perinatal lethality in Dcc (-/-) mice. Expression analyses using in situ hybridization and immunohistochemistry showed Dcc expression in the mouse vestibular ganglion (E15.5), and utricle and crista ampullaris (6-week-old), respectively. In summary, we report the first GWAS for vestibular functional variation in inbred mice and provide evidence for the role of Dcc in the normal innervation of the peripheral vestibular system. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
23. Expression and Physiology of Voltage-Gated Sodium Channels in Developing Human Inner Ear
- Author
-
Rikki K. Quinn, Hannah R. Drury, Ethan T. Cresswell, Melissa A. Tadros, Bryony A. Nayagam, Robert J. Callister, Alan M. Brichta, and Rebecca Lim
- Subjects
inner ear ,cochlea ,Neurosciences. Biological psychiatry. Neuropsychiatry ,Biology ,Utricle ,medicine ,otorhinolaryngologic diseases ,Inner ear ,human ,development ,Cochlea ,Vestibular Hair Cell ,Original Research ,Vestibular system ,vestibular ,General Neuroscience ,Sodium channel ,electrophysiology ,Cell biology ,Neuroepithelial cell ,Crista ,medicine.anatomical_structure ,PCR ,sense organs ,Neuroscience ,sodium channel ,RC321-571 - Abstract
Sodium channel expression in inner ear afferents is essential for the transmission of vestibular and auditory information to the central nervous system. During development, however, there is also a transient expression of Na+ channels in vestibular and auditory hair cells. Using qPCR analysis, we describe the expression of four Na+ channel genes, SCN5A (Nav1.5), SCN8A (Nav1.6), SCN9A (Nav1.7), and SCN10A (Nav1.8) in the human fetal cristae ampullares, utricle, and base, middle, and apex of the cochlea. Our data show distinct patterns of Na+ channel gene expression with age and between these inner ear organs. In the utricle, there was a general trend toward fold-change increases in expression of SCN8A, SCN9A, and SCN10A with age, while the crista exhibited fold-change increases in SCN5A and SCN8A and fold-change decreases in SCN9A and SCN10A. Fold-change differences of each gene in the cochlea were more complex and likely related to distinct patterns of expression based on tonotopy. Generally, the relative expression of SCN genes in the cochlea was greater than that in utricle and cristae ampullares. We also recorded Na+ currents from developing human vestibular hair cells aged 10–11 weeks gestation (WG), 12–13 WG, and 14+ WG and found there is a decrease in the number of vestibular hair cells that exhibit Na+ currents with increasing gestational age. Na+ current properties and responses to the application of tetrodotoxin (TTX; 1 μM) in human fetal vestibular hair cells are consistent with those recorded in other species during embryonic and postnatal development. Both TTX-sensitive and TTX-resistant currents are present in human fetal vestibular hair cells. These results provide a timeline of sodium channel gene expression in inner ear neuroepithelium and the physiological characterization of Na+ currents in human fetal vestibular neuroepithelium. Understanding the normal developmental timeline of ion channel gene expression and when cells express functional ion channels is essential information for regenerative technologies.
- Published
- 2021
24. Diferentes níveis de energia metabolizável para galos reprodutores de corte com ou sem retirada da crista Different levels of metabolizable energy for broiler breeders of cutting with or without the crest cutting
- Author
-
Walter Lucca, Alexandre Pires Rosa, Rodrigo Uttpatel, Harvey Machado, Camila Borba Santos, and Vivian Barcelos
- Subjects
nutrição ,crista ,reprodutores de corte ,fertilidade ,nutrition ,crest ,breeders of cutting ,fertility ,Agriculture ,Agriculture (General) ,S1-972 - Abstract
O experimento foi conduzido com o objetivo de avaliar qual o melhor nível energético na dieta para galos reprodutores de corte da linhagem Cobb 500 e a influência da presença da crista em parâmetros como: peso corporal, volume de sêmen, concentração de células espermáticas e fertilidade. Foram utilizados 32 galos de 22 até 44 semanas de idade, distribuídos aleatoriamente em gaiolas metálicas com comedouro e bebedouro tipo calha. Utilizou-se um delineamento experimental inteiramente casualizado, em esquema fatorial 2x2, sendo dois níveis de energia (2600 e 2800kcal EM kg-1) e duas condições de crista (com e sem corte), formando quatro tratamentos com oito repetições, com uma ave por unidade experimental. Na 24ª semana, iniciou-se a coleta de dados para a análise estatística, sempre intercalando a semana de pesagem das aves com a coleta de sêmen, o qual foi coletado através do método Americano e, para contagem de células espermáticas, fez-se a diluição do sêmen a base de formol salina tamponada para posterior leitura na câmara de Neubauer. Avaliou-se a fertilidade dos machos inseminando artificialmente seis fêmeas por tratamento, duas vezes por semana com 0,05mL de sêmen por fêmea. Os ovos foram coletados quatro vezes por dia, identificados, desinfetados e incubados em condições similares. No 21° dia de incubação, os ovos que não eclodiram foram quebrados e examinados macroscopicamente para calcular a fertilidade. Os níveis de energia estudados não revelaram diferença significativa no peso corporal e no volume de sêmen dos galos durante o período experimental. Já o corte da crista reduziu 9,5% do peso corporal e 24% da fertilidade em relação a aves com crista inteira. Nas semanas 29ª, 35ª, 37ª, e 43ª, observou-se maior concentração de células espermáticas em aves que receberam dieta com 2600kcal EM kg-1. Conclui-se que o nível de 2600kcal EM kg-1 é suficiente para atender os parâmetros reprodutivos dos galos e a presença da crista é fundamental para manter a alta fertilidade em aves de 42 e 43 semanas de idade.The experiment was carried out to evaluate which is the best the diet energy level diet for male broiler breeders of cutting Cobb 500 and the influence of the presence of the crest on parameters such as body weight, semen volume, sperm cell concentration and fertility. Were used 32 roosters for 22 to 44 weeks of age, they were randomly assigned to cages equipped with feeders and drinkers type gutter. The experimental design was entirely casualized in a factorial scheme 2x2 two comb conditions (with and without crest) and two levels of metabolizable energy (2600 and 2800kcal kg-1). There was four treatments with eight replications, with one bird per experimental unit. At week 24th began collecting data for statistical analysis, when merging the week weighing the birds to the collection of semen, which was collected through the American method and count of sperm cells, The dilution of semen-based formaldehyde buffered saline and then reading in a Neubauer chamber. We assessed male fertility through artificial insemination of six females per treatment, twice weekly with 0.05mL of semen per female. Eggs were collected four times a day, identified, disinfected and incubated in the same conditions. After 21 of incubation, eggs not hatched were broken and macroscopically examined to calculate the fertility. The energy levels studied revealed no significant difference in body weight and volume of semen of roosters during the experimental period. Since cutting the crest reduced body weight and fertility of 9.5% and 24% respectively in relation to birds crested whole. In the weeks 29th, 35th, 37th and 43th there was a higher concentration of sperm cells in birds fed the diet with 2600kcal kg-1. It is concluded that the level of 2600kcal kg-1 is sufficient to meet the reproductive parameters of roosters and the presence of the crest is needed to maintaining high fertility in 42 and 43 weeks of age birds.
- Published
- 2011
- Full Text
- View/download PDF
25. Efeito de dois níveis de proteína para machos reprodutores de corte com e sem retirada da crista Effect of two levels of protein for broiler breeders males with and without retreat of the crest
- Author
-
Walter Lucca, Alexandre Pires Rosa, Rodrigo Uttpatel, Elenice Zucuni Franco, Harvey Machado de Souza, and Leandro Irion Acosta
- Subjects
fertilidade ,crista ,reprodutor de corte ,proteína bruta ,fertility ,crest ,broiler breeders males ,crude protein ,Agriculture ,Agriculture (General) ,S1-972 - Abstract
O objetivo deste experimento foi avaliar o efeito de diferentes níveis de proteína bruta (PB) na dieta para machos com ou sem crista. Peso corporal, volume de sêmen, número de células espermáticas e fertilidade foram os parâmetros avaliados. Foram utilizados 32 machos Cobb 500, 50% com crista inteira e 50% sem crista. Todos os machos foram submetidos às mesmas condições de manejo. Eles foram alojados em gaiolas metálicas individuais, com comedouro e bebedouro. O delineamento experimental usado foi o inteiramente casualizado com esquema fatorial 2x2, com duas condições de crista (com e sem) e dois níveis de proteína bruta (12 e 16%). O sêmen foi coletado por meio do método americano e o número de células espermáticas foi determinado por meio da câmara de Neubauer. Na 42ª, 43ª e 44ª semanas de idade, seis fêmeas para cada tratamento foram inseminadas artificialmente. As inseminações foram realizadas duas vezes por semana com sêmen fresco na dose de 0,05ml. Os ovos foram coletados quatro vezes por dia, identificados, desinfetados e incubados nas mesmas condições. Depois de 21 dias de incubação, os ovos foram quebrados e examinados macroscopicamente para análise da fertilidade. O nível de 12% de proteína bruta foi suficiente para atender as exigências reprodutivas, e a permanência da crista influenciou apenas o peso corporal dos machos, em que machos com crista apresentaram maior peso corporal.The objective of this trial was evaluated the effect of different crude protein (CP) levels of diet for males with or without coumbing. Body weight, semen volume, number of spermatic cells and fertility were evaluated. A total of 32 males Cobb 500 were used being 50% coumbed and 50% decoumbed males. The roosters were exposed the same management conditions in starting and rearing phases. They were housed in individual metallic cages with feeders and drinkers. The experimental design was entirely casualized in a factorial 2x2, two comb conditions (with or without) and two levels of crude protein (12 and 16%). Semen was collected using the American methods and number of spermatic cells was determined by counting in Neubauer chamber. At 42, 43 and 44 weeks of age, six females were artificially inseminated by treatment, twice a week, with dosage of 0.05ml of fresh semen. The eggs were collected four times a day, identified, disinfected and incubated in similar conditions. After 21 day of incubation they were broken and examined macroscopically to analyze the fertility. The level of 12% of crude protein was enough to assist the reproductive demands and the permanence of males. Combed males had body weight higher than without combed males.
- Published
- 2009
- Full Text
- View/download PDF
26. Tuned vibration modes in a miniature hearing organ
- Author
-
Marcel G. A. van der Heijden, Anna Vavakou, Jan Scherberich, Manuela Nowotny, and Neurosciences
- Subjects
Tympanic Membrane ,Acoustics ,Ear, Middle ,Sensory system ,Vibration ,Gryllidae ,Hearing ,Optical coherence tomography ,Frequency separation ,otorhinolaryngologic diseases ,medicine ,Animals ,Cochlea ,insect hearing ,Physics ,optical coherence tomography ,Multidisciplinary ,medicine.diagnostic_test ,Biological Sciences ,crista acustica ,Mecopoda elongata ,Crista ,Sound ,Acoustic Stimulation ,Tonotopy ,Transduction (physiology) ,Neuroscience - Abstract
Significance Most hearing organs contain an array of sensory cells that act as miniature microphones, each tuned to its own frequency like piano strings. Acoustically communicating insects like bushcrickets have evolved miniscule hearing organs, typically smaller than 1 mm, in their forelegs. It is still unknown how the sensory structures inside the leg vibrate in response to sound. Using advanced imaging techniques, we meticulously mapped the nanovibrations in the bushcricket ear. We discovered a complex motion pattern in which structures separated by only 1/50 mm showed systematic tuning differences. Despite the insect ear’s tiny dimensions, its mode of operation strikingly resembled that of vertebrate ears. Apparently, evolution has provided similar solutions to the spectral processing of sounds., Bushcrickets (katydids) rely on only 20 to 120 sensory units located in their forelegs to sense sound. Situated in tiny hearing organs less than 1 mm long (40× shorter than the human cochlea), they cover a wide frequency range from 1 kHz up to ultrasounds, in tonotopic order. The underlying mechanisms of this miniaturized frequency-place map are unknown. Sensory dendrites in the hearing organ (crista acustica [CA]) are hypothesized to stretch, thereby driving mechanostransduction and frequency tuning. However, this has not been experimentally confirmed. Using optical coherence tomography (OCT) vibrometry, we measured the relative motion of structures within and adjacent to the CA of the bushcricket Mecopoda elongata. We found different modes of nanovibration in the CA that have not been previously described. The two tympana and the adjacent septum of the foreleg that enclose the CA were recorded simultaneously, revealing an antiphasic lever motion strikingly reminiscent of vertebrate middle ears. Over the entire length of the CA, we were able to separate and compare vibrations of the top (cap cells) and base (dorsal wall) of the sensory tissue. The tuning of these two structures, only 15 to 60 μm (micrometer) apart, differed systematically in sharpness and best frequency, revealing a tuned periodic deformation of the CA. The relative motion of the two structures, a potential drive of transduction, demonstrated sharper tuning than either of them. The micromechanical complexity indicates that the bushcricket ear invokes multiple degrees of freedom to achieve frequency separation with a limited number of sensory cells.
- Published
- 2021
27. Kv1 channels and neural processing in vestibular calyx afferents
- Author
-
Frances L Meredith, Matthew E Kirk, and Katherine J Rennie
- Subjects
Gerbil ,gravity ,Utricle ,Crista ,Margatoxin ,Potassium conductance ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
Potassium-selective ion channels are important for accurate transmission of signals from auditory and vestibular sensory end organs to their targets in the central nervous system. During different gravity conditions, astronauts experience altered input signals from the peripheral vestibular system resulting in sensorimotor dysfunction. Adaptation to altered sensory input occurs, but it is not explicitly known whether this involves synaptic modifications within the vestibular epithelia. Future investigations of such potential plasticity require a better understanding of the electrophysiological mechanisms underlying the known heterogeneity of afferent discharge under normal conditions. This study advances this understanding by examining the role of the Kv1 potassium channel family in mediating action potentials in specialized vestibular afferent calyx endings in the gerbil crista and utricle. Pharmacological agents selective for different sub-types of Kv1 channels were tested on membrane responses in whole cell recordings in the crista. Kv1 channels sensitive to α-dendrotoxin and dendrotoxin-K were found to prevail in the central regions, whereas K+ channels sensitive to margatoxin, which blocks Kv1.3 and 1.6 channels, were more prominent in peripheral regions. Margatoxin-sensitive currents showed voltage-dependent inactivation. Dendrotoxin-sensitive currents showed no inactivation and dampened excitability in calyces in central neuroepithelial regions. The differential distribution of Kv1 potassium channels in vestibular afferents supports their importance in accurately relaying gravitational and head movement signals through specialized lines to the central nervous system. Pharmacological modulation of specific groups of K+ channels could help alleviate vestibular dysfunction on earth and in space.
- Published
- 2015
- Full Text
- View/download PDF
28. Channeling your inner ear potassium: K+ channels in vestibular hair cells.
- Author
-
Meredith, Frances L. and Rennie, Katherine J.
- Subjects
- *
INNER ear physiology , *POTASSIUM channels , *IONIC conductivity , *HAIR cells , *CELL receptors , *AMNIOTES - Abstract
During development of vestibular hair cells, K + conductances are acquired in a specific pattern. Functionally mature vestibular hair cells express different complements of K + channels which uniquely shape the hair cell receptor potential and filtering properties. In amniote species, type I hair cells (HCI) have a large input conductance due to a ubiquitous low–voltage-activated K + current that activates with slow sigmoidal kinetics at voltages negative to the membrane resting potential. In contrast type II hair cells (HCII) from mammalian and non-mammalian species have voltage-dependent outward K + currents that activate rapidly at or above the resting membrane potential and show significant inactivation. A-type, delayed rectifier and calcium-activated K + channels contribute to the outward K + conductance and are present in varying proportions in HCII. In many species, K + currents in HCII in peripheral locations of vestibular epithelia inactivate more than HCII in more central locations. Two types of inward rectifier currents have been described in both HCI and HCII. A rapidly activating K + -selective inward rectifier current (I K1 , mediated by Kir2.1 channels) predominates in HCII in peripheral zones, whereas a slower mixed cation inward rectifier current (I h ), shows greater expression in HCII in central zones of vestibular epithelia. The implications for sensory coding of vestibular signals by different types of hair cells are discussed. This article is part of a Special Issue entitled
. [ABSTRACT FROM AUTHOR] - Published
- 2016
- Full Text
- View/download PDF
29. Mitochondrial Contact Site and Cristae Organization System and F 1 F O -ATP Synthase Crosstalk Is a Fundamental Property of Mitochondrial Cristae
- Author
-
Hassan Hashimi, Alena Zíková, Lawrence Rudy Cadena, Ondřej Gahura, and Brian Panicucci
- Subjects
0301 basic medicine ,Most recent common ancestor ,biology ,ATP synthase ,Protein subunit ,Mitochondrion ,Trypanosoma brucei ,biology.organism_classification ,Microbiology ,QR1-502 ,Cell biology ,03 medical and health sciences ,Crista ,Crosstalk (biology) ,030104 developmental biology ,0302 clinical medicine ,parasitic diseases ,biology.protein ,Inner membrane ,Molecular Biology ,030217 neurology & neurosurgery - Abstract
Mitochondrial cristae are polymorphic invaginations of the inner membrane that are the fabric of cellular respiration. Both the mitochondrial contact site and cristae organization system (MICOS) and the F1FO-ATP synthase are vital for sculpting cristae by opposing membrane-bending forces. While MICOS promotes negative curvature at crista junctions, dimeric F1FO-ATP synthase is crucial for positive curvature at crista rims. Crosstalk between these two complexes has been observed in baker's yeast, the model organism of the Opisthokonta supergroup. Here, we report that this property is conserved in Trypanosoma brucei, a member of the Discoba clade that separated from the Opisthokonta ∼2 billion years ago. Specifically, one of the paralogs of the core MICOS subunit Mic10 interacts with dimeric F1FO-ATP synthase, whereas the other core Mic60 subunit has a counteractive effect on F1FO-ATP synthase oligomerization. This is evocative of the nature of MICOS-F1FO-ATP synthase crosstalk in yeast, which is remarkable given the diversification that these two complexes have undergone during almost 2 eons of independent evolution. Furthermore, we identified a highly diverged, putative homolog of subunit e, which is essential for the stability of F1FO-ATP synthase dimers in yeast. Just like subunit e, it is preferentially associated with dimers and interacts with Mic10, and its silencing results in severe defects to cristae and the disintegration of F1FO-ATP synthase dimers. Our findings indicate that crosstalk between MICOS and dimeric F1FO-ATP synthase is a fundamental property impacting crista shape throughout eukaryotes. IMPORTANCE Mitochondria have undergone profound diversification in separate lineages that have radiated since the last common ancestor of eukaryotes some eons ago. Most eukaryotes are unicellular protists, including etiological agents of infectious diseases, like Trypanosoma brucei. Thus, the study of a broad range of protists can reveal fundamental features shared by all eukaryotes and lineage-specific innovations. Here, we report that two different protein complexes, MICOS and F1FO-ATP synthase, known to affect mitochondrial architecture, undergo crosstalk in T. brucei, just as in baker's yeast. This is remarkable considering that these complexes have otherwise undergone many changes during their almost 2 billion years of independent evolution. Thus, this crosstalk is a fundamental property needed to maintain proper mitochondrial structure even if the constituent players considerably diverged.
- Published
- 2021
30. Avulsão indireta da epífise da crista ilíaca: uma rara lesão Indirect avulsion of the iliac crest epiphysis: a rare lesion
- Author
-
Gilberto José Cação Pereira, Hamilton da Rosa Pereira, and Márcio Cruz
- Subjects
Epífise ,ilíaco ,crista ,avulsão ,indireta ,trauma ,Epiphysis ,iliac ,crest ,avulsion ,indirect ,Medicine ,Orthopedic surgery ,RD701-811 - Abstract
A avulsão da cartilagem da crista ilíaca é uma lesão infreqüente e raramente é descrita na literatura. Atletas jovens e adolescentes são os indivíduos mais predispostos à lesão. O trauma indireto causado pela contração da musculatura aderida à crista ilíaca e o movimento de angulação do tronco em sentido oposto ao da contração é o mecanismo mais comum de arrancamento da cartilagem. Como na maioria dos casos não existe trauma direto, esses podem não ser diagnosticados se não considerarmos essa possibilidade de lesão. Relatamos dois casos atendidos em nosso Serviço, que apresentaram lesão na cartilagem devido a um trauma indireto (contração muscular abrupta). Ambos foram tratados de maneira incruenta, com excelente evolução.Avulsion of the iliac crest cartilage is an infrequent, rarely described lesion. Young and adolescent athletes are prone to this lesion. Indirect trauma caused by contraction of the muscles inserted at the iliac crest and the angulation move-ment of the trunk in direction opposite to the contraction is the most common mechanism causing cartilage tearing. As most of the cases do not present direct trauma, diagnosis can be missed if that possibility is not considered. Two cases attended by our Service are described. Lesion in the cartilage was observed due to an indirect trauma (abrupt muscular contraction). Both cases were treated and the evoluti-on was excellent.
- Published
- 2002
- Full Text
- View/download PDF
31. Myristoyl group-aided protein import into the mitochondrial intermembrane space
- Author
-
Eri Ueda, Yasushi Tamura, Shunsuke Matsumoto, Toshiya Endo, Chika Kakuta, Shin Kawano, and Haruka Sakaue
- Subjects
0301 basic medicine ,Saccharomyces cerevisiae Proteins ,Mitochondrial intermembrane space ,lcsh:Medicine ,TIM/TOM complex ,Saccharomyces cerevisiae ,Mitochondrion ,Article ,Mitochondrial Proteins ,03 medical and health sciences ,0302 clinical medicine ,lcsh:Science ,Myristoylation ,Multidisciplinary ,MICOS complex ,Chemistry ,lcsh:R ,Mitochondria ,Cell biology ,Protein Transport ,Crista ,030104 developmental biology ,Mitochondrial Membranes ,lcsh:Q ,Intermembrane space ,Bacterial outer membrane ,030217 neurology & neurosurgery - Abstract
The MICOS complex mediates formation of the crista junctions in mitochondria. Here we analyzed the mitochondrial import pathways for the six yeast MICOS subunits as a step toward understanding of the assembly mechanisms of the MICOS complex. Mic10, Mic12, Mic26, Mic27, and Mic60 used the presequence pathway to reach the intermembrane space (IMS). In contrast, Mic19 took the TIM40/MIA pathway, through its CHCH domain, to reach the IMS. Unlike canonical TIM40/MIA substrates, presence of the N-terminal unfolded DUF domain impaired the import efficiency of Mic19, yet N-terminal myristoylation of Mic19 circumvented this effect. The myristoyl group of Mic19 binds to Tom20 of the TOM complex as well as the outer membrane, which may lead to “entropy pushing” of the DUF domain followed by the CHCH domain of Mic19 into the import channel, thereby achieving efficient import.
- Published
- 2019
32. Ophirina amphinema n. gen., n. sp., a New Deeply Branching Discobid with Phylogenetic Affinity to Jakobids
- Author
-
Eunsoo Kim, Yangtsho Gyaltshen, Akinori Yabuki, Katsunori Fujikura, and Aaron A. Heiss
- Subjects
0106 biological sciences ,0301 basic medicine ,lcsh:Medicine ,Flagellum ,010603 evolutionary biology ,01 natural sciences ,Article ,03 medical and health sciences ,Phylogenetics ,RNA, Ribosomal, 18S ,Basal body ,Flagellate ,lcsh:Science ,Phylogeny ,Multidisciplinary ,biology ,Phylogenetic tree ,lcsh:R ,Eukaryota ,Genomics ,biology.organism_classification ,Crista ,030104 developmental biology ,Body plan ,Genes, Mitochondrial ,Evolutionary biology ,Genome, Mitochondrial ,Ultrastructure ,lcsh:Q - Abstract
We report a novel nanoflagellate, Ophirina amphinema n. gen. n. sp., isolated from a lagoon of the Solomon Islands. The flagellate displays ‘typical excavate’ morphological characteristics, such as the presence of a ventral feeding groove with vanes on the posterior flagellum. The cell is ca. 4 µm in length, bears two flagella, and has a single mitochondrion with flat to discoid cristae. The flagellate exists in two morphotypes: a suspension-feeder, which bears flagella that are about the length of the cell, and a swimmer, which has longer flagella. In a tree based on the analysis of 156 proteins, Ophirina is sister to jakobids, with moderate bootstrap support. Ophirina has some ultrastructural (e.g. B-fibre associated with the posterior basal body) and mtDNA (e.g. rpoA–D) features in common with jakobids. Yet, other morphological features, including the crista morphology and presence of two flagellar vanes, rather connect Ophirina to non-jakobid or non-discobid excavates. Ophirina amphinema has some unique features, such as an unusual segmented core structure within the basal bodies and a rightward-oriented dorsal fan. Thus, Ophirina represents a new deeply-branching member of Discoba, and its mosaic morphological characteristics may illuminate aspects of the ancestral eukaryotic cellular body plan.
- Published
- 2018
33. Tmc Reliance Is Biased by the Hair Cell Subtype and Position Within the Ear
- Author
-
Shaoyuan Zhu, Zongwei Chen, Haoming Wang, and Brian M. McDermott
- Subjects
Short hair ,Cell morphology ,hair cell ,Cell and Developmental Biology ,medicine ,otorhinolaryngologic diseases ,Mechanotransduction ,Zebrafish ,lcsh:QH301-705.5 ,mechanotransduction ,Vestibular system ,biology ,integumentary system ,Tmc ,balance ,Cell Biology ,Brief Research Report ,biology.organism_classification ,zebrafish ,Cell biology ,Crista ,medicine.anatomical_structure ,lcsh:Biology (General) ,hearing ,Saccule ,Hair cell ,sense organs ,Developmental Biology - Abstract
Hair cells are heterogenous, enabling varied roles in sensory systems. An emerging hypothesis is that the transmembrane channel-like (Tmc) proteins of the hair cell’s mechanotransduction apparatus vary within and between organs to permit encoding of different mechanical stimuli. Five anatomical variables that may coincide with different Tmc use by a hair cell within the ear are the containing organ, cell morphology, cell position within an organ, axis of best sensitivity for the cell, and the hair bundle’s orientation within this axis. Here, we test this hypothesis in the organs of the zebrafish ear using a suite of genetic mutations. Transgenesis and quantitative measurements demonstrate two morphologically distinct hair cell types in the central thickness of a vestibular organ, the lateral crista: short and tall. In contrast to what has been observed, we find that tall hair cells that lack Tmc1 generally have substantial reductions in mechanosensitivity. In short hair cells that lack Tmc2 isoforms, mechanotransduction is largely abated. However, hair cell Tmc dependencies are not absolute, and an exceptional class of short hair cell that depends on Tmc1 is present, termed a short hair cell erratic. To further test anatomical variables that may influence Tmc use, we map Tmc1 function in the saccule of mutant larvae that depend just on this Tmc protein to hear. We demonstrate that hair cells that use Tmc1 are found in the posterior region of the saccule, within a single axis of best sensitivity, and hair bundles with opposite orientations retain function. Overall, we determine that Tmc reliance in the ear is dependent on the organ, subtype of hair cell, position within the ear, and axis of best sensitivity.
- Published
- 2021
34. Kv1 channels and neural processing in vestibular calyx afferents.
- Author
-
Meredith, Frances L., Kirk, Matthew E., and Rennie, Katherine J.
- Subjects
NEUROLOGY ,CALYX ,VESTIBULAR apparatus ,CENTRAL nervous system ,POTASSIUM - Abstract
Potassium-selective ion channels are important for accurate transmission of signals from auditory and vestibular sensory end organs to their targets in the central nervous system. During different gravity conditions, astronauts experience altered input signals from the peripheral vestibular system resulting in sensorimotor dysfunction. Adaptation to altered sensory input occurs, but it is not explicitly known whether this involves synaptic modifications within the vestibular epithelia. Future investigations of such potential plasticity require a better understanding of the electrophysiological mechanisms underlying the known heterogeneity of afferent discharge under normal conditions. This study advances this understanding by examining the role of the Kv1 potassium channel family in mediating action potentials in specialized vestibular afferent calyx endings in the gerbil crista and utricle. Pharmacological agents selective for different sub-types of Kv1 channels were tested on membrane responses in whole cell recordings in the crista. Kv1 channels sensitive to a-dendrotoxin and dendrotoxin-K were found to prevail in the central regions, whereas K
+ channels sensitive to margatoxin, which blocks Kv1.3 and 1.6 channels, were more prominent in peripheral regions. Margatoxin-sensitive currents showed voltage-dependent inactivation. Dendrotoxin-sensitive currents showed no inactivation and dampened excitability in calyces in central neuroepithelial regions. The differential distribution of Kv1 potassium channels in vestibular afferents supports their importance in accurately relaying gravitational and head movement signals through specialized lines to the central nervous system. Pharmacological modulation of specific groups of K+ channels could help alleviate vestibular dysfunction on earth and in space. [ABSTRACT FROM AUTHOR]- Published
- 2015
- Full Text
- View/download PDF
35. Comparative micromechanics of bushcricket ears with and without a specialized auditory fovea region in the crista acustica
- Author
-
Manuela Nowotny, Alexander Stoessel, Jan Scherberich, and Roxana Taszus
- Subjects
0106 biological sciences ,genetic structures ,media_common.quotation_subject ,Tettigoniidae ,Sensory system ,010603 evolutionary biology ,01 natural sciences ,General Biochemistry, Genetics and Molecular Biology ,Gryllidae ,03 medical and health sciences ,Hearing ,Foveal ,Perception ,otorhinolaryngologic diseases ,Animals ,030304 developmental biology ,General Environmental Science ,media_common ,0303 health sciences ,Morphology and Biomechanics ,travelling wave ,General Immunology and Microbiology ,biology ,Ear ,auditory fovea ,General Medicine ,Anatomy ,biology.organism_classification ,Crista ,Sound ,Fenestrata ,sexual dimorphism ,insect ,sense organs ,Phaneropterinae ,General Agricultural and Biological Sciences ,Transduction (physiology) ,Research Article - Abstract
In some insects and vertebrate species, the specific enlargement of sensory cell epithelium facilitates the perception of particular behaviourally relevant signals. The insect auditory fovea in the ear of the bushcricket Ancylecha fenestrata (Tettigoniidae: Phaneropterinae) is an example of such an expansion of sensory epithelium. Bushcricket ears developed in convergent evolution anatomical and functional similarities to mammal ears, such as travelling waves and auditory foveae, to process information by sound. As in vertebrate ears, sound induces a motion of this insect hearing organ (crista acustica), which can be characterized by its amplitude and phase response. However, detailed micromechanics in this bushcricket ear with an auditory fovea are yet unknown. Here, we fill this gap in knowledge for bushcricket, by analysing and comparing the ear micromechanics in Ancylecha fenestrata and a bushcricket species without auditory fovea (Mecopoda elongata, Tettigoniidae: Mecopodinae) using laser-Doppler vibrometry. We found that the increased size of the crista acustica, expanded by a foveal region in A. fenestrata, leads to higher mechanical amplitudes and longer phase delays in A. fenestrata male ears. Furthermore, area under curve analyses of the organ oscillations reveal that more sensory units are activated by the same stimuli in the males of the auditory fovea-possessing species A. fenestrata. The measured increase of phase delay in the region of the auditory fovea supports the conclusion that tilting of the transduction site is important for the effective opening of the involved transduction channels. Our detailed analysis of sound-induced micromechanics in this bushcricket ear demonstrates that an increase of sensory epithelium with foveal characteristics can enhance signal detection and may also improve the neuronal encoding. Introduction. - Material and methods (animals and preparation, micro-computed tomography, laser-doppler vibrometry and sound stimulation, data analysis and statistics). - Results. - Discussion
- Published
- 2020
36. Protonic Capacitor: Elucidating the biological significance of mitochondrial cristae formation
- Author
-
James Weifu Lee
- Subjects
Cell biology ,Bioenergetics ,Energy science and technology ,Biophysics ,lcsh:Medicine ,Mitochondrion ,Biochemistry ,Article ,chemistry.chemical_compound ,Adenosine Triphosphate ,Cardiolipin ,Animals ,Humans ,Inner mitochondrial membrane ,lcsh:Science ,Membrane potential ,Membrane Potential, Mitochondrial ,Multidisciplinary ,ATP synthase ,biology ,Physics ,lcsh:R ,Models, Theoretical ,Crista ,Chemistry ,Membrane ,chemistry ,Mitochondrial Membranes ,biology.protein ,lcsh:Q ,Protons - Abstract
For decades, it was not entirely clear why mitochondria develop cristae? The work employing the transmembrane-electrostatic proton localization theory reported here has now provided a clear answer to this fundamental question. Surprisingly, the transmembrane-electrostatically localized proton concentration at a curved mitochondrial crista tip can be significantly higher than that at the relatively flat membrane plane regions where the proton-pumping respiratory supercomplexes are situated. The biological significance for mitochondrial cristae has now, for the first time, been elucidated at a protonic bioenergetics level: 1) The formation of cristae creates more mitochondrial inner membrane surface area and thus more protonic capacitance for transmembrane-electrostatically localized proton energy storage; and 2) The geometric effect of a mitochondrial crista enhances the transmembrane-electrostatically localized proton density to the crista tip where the ATP synthase can readily utilize the localized proton density to drive ATP synthesis.
- Published
- 2020
37. Brownian dynamics simulation of cytochrome c diffusion and binding with cytochrome c1 in mitochondrial crista
- Author
-
Galina Riznichenko, Nadezda A. Brazhe, Andrei B. Rubin, Ilya B. Kovalenko, and A. M. Abaturova
- Subjects
0301 basic medicine ,ATP synthase ,biology ,lcsh:T58.5-58.64 ,lcsh:Information technology ,Cytochrome c ,Oxidative phosphorylation ,01 natural sciences ,Electron transport chain ,010101 applied mathematics ,03 medical and health sciences ,Crista ,030104 developmental biology ,Cytochrome C1 ,Coenzyme Q – cytochrome c reductase ,biology.protein ,Biophysics ,0101 mathematics ,Intermembrane space - Abstract
Cytochrome c (Cc) protein shuttles electrons from respiratory chain complex III — from cytochrome c1 (Cc1) subunit — to complex IV during oxidative phosphorylation, in intermembrane space of mitochondria and cristae lumen. With Leigh syndrome (LS), the crista lumen width (CLW) increases, and ATP production declines. One of the questions raised by this situation is to find out how ATP production impairs at LS. Using the simulation of Brownian dynamics, we tested whether the increase in CLW declines respiration at the stage of electron transport of Cc to Cc1. We designed a Brownian dynamics model of horse Cc diffusion and binding with bovine Cc1 in solution by the ProKSim software. The values of the model parameters were estimated to obtain the same dependence of the second-order association rate constant on the ionic strength as in the experiment [1]. Estimated values of the model parameters were used in the model of the reaction in the cristae lumen. The model scene was a parallelepiped. The distance between the two surfaces simulated crystal membranes varied. We received increasing of half-life time of Cc diffusion and binding with Cc1 at increasing CLW. For membrane surface 90Åx100Å (close to the membrane size of complex III), the half-life time of the process changed from 0.098 to 0.22 µs with increasing cristae lumen width from 120 to 160 Å. But due to the half-life time of electron transfer between proteins in the complex, estimated in [1], is higher (100.5µs), the overall time shouldn’t change. To simulate impair of ATP production in the model with an increase in the crista lumen width, we probably need to add to the model IV complex and take into account the dimerization defect of ATP synthase.
- Published
- 2020
38. Inhibition of K Currents in Type I Vestibular Hair Cells by Gentamicin and Neomycin.
- Author
-
Mann, Scott E., Johnson, Matthew, Meredith, Frances L., and Rennie, Katherine J.
- Subjects
- *
POTASSIUM channels , *VESTIBULAR apparatus diseases , *HAIR cells , *GENTAMICIN , *NEOMYCIN , *THERAPEUTICS - Abstract
Significant ototoxicity limits the use of aminoglycoside (AG) antibiotics. Several mechanisms may contribute to the death of both auditory and vestibular hair cells. In this study the effects of gentamicin and neomycin on K+ currents in mature and early postnatal type I vestibular hair cells (HCI) were tested directly. The whole-cell patch clamp technique was used to assess the effects of AG and KCNQ channel modulators on K+ currents (IK) in HCI acutely isolated from gerbil semicircular canals. Extracellular neomycin (1 mM) rapidly reduced peak outward IK by 16 ± 4% (n = 9) in mature HCI (postnatal days, P, 25-66). Gentamicin (5 mM) reduced outward IK by 16 ± 3% (n = 8). A similar reduction in outward current was seen in immature HCI (P5-9) that lacked the low-voltage-activated component of IK observed in mature cells. Intracellular application of gentamicin and neomycin also reduced IK in mature HCI. Modulators of KCNQ channels were used to probe KCNQ channel involvement. The selective KCNQ antagonist XE991 did not reduce IK and the neomycin-induced reduction in IK was not reversed by the KCNQ agonist flupirtine. Application of intracellular poly-D-lysine to sequester PIP2 did not reduce IK. Application of the K+ channel blocker 4-aminopyridine (4-AP) strongly reduced IK, and extracellular AG in the presence of 4-AP gave no further inhibition of IK. In summary, AG significantly reduce the 4-AP-sensitive IK in early postnatal and mature HCI. K+ current inhibition differs from that seen in outer hair cells, since it does not appear to involve PIP2 sequestration or KCNQ channels. Copyright © 2013 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
39. Erratum: Dopaminergic Inhibition of Na+ Currents in Vestibular Inner Ear Afferents.
- Author
-
Frontiers Production Office
- Subjects
INNER ear ,AFFERENT pathways ,SEMICIRCULAR canals ,SODIUM channels ,HAIR cells - Published
- 2022
- Full Text
- View/download PDF
40. Hyperpolarization-Activated Current ( I) in Vestibular Calyx Terminals: Characterization and Role in Shaping Postsynaptic Events.
- Author
-
Meredith, Frances, Benke, Tim, and Rennie, Katherine
- Abstract
Calyx afferent terminals engulf the basolateral region of type I vestibular hair cells, and synaptic transmission across the vestibular type I hair cell/calyx is not well understood. Calyces express several ionic conductances, which may shape postsynaptic potentials. These include previously described tetrodotoxin-sensitive inward Na currents, voltage-dependent outward K currents and a K(Ca) current. Here, we characterize an inwardly rectifying conductance in gerbil semicircular canal calyx terminals (postnatal days 3-45), sensitive to voltage and to cyclic nucleotides. Using whole-cell patch clamp, we recorded from isolated calyx terminals still attached to their type I hair cells. A slowly activating, noninactivating current ( I) was seen with hyperpolarizing voltage steps negative to the resting potential. External Cs (1-5 mM) and ZD7288 (100 μM) blocked the inward current by 97 and 83 %, respectively, confirming that I was carried by hyperpolarization-activated, cyclic nucleotide gated channels. Mean half-activation voltage of I was −123 mV, which shifted to −114 mV in the presence of cAMP. Activation of I was well described with a third order exponential fit to the current (mean time constant of activation, τ, was 190 ms at −139 mV). Activation speeded up significantly ( τ = 136 and 127 ms, respectively) when intracellular cAMP and cGMP were present, suggesting that in vivo I could be subject to efferent modulation via cyclic nucleotide-dependent mechanisms. In current clamp, hyperpolarizing current steps produced a time-dependent depolarizing sag followed by either a rebound afterdepolarization or an action potential. Spontaneous excitatory postsynaptic potentials (EPSPs) became larger and wider when I was blocked with ZD7288. In a three-dimensional mathematical model of the calyx terminal based on Hodgkin-Huxley type ionic conductances, removal of I similarly increased the EPSP, whereas cAMP slightly decreased simulated EPSP size and width. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
41. Postnatal expression of an apamin-sensitive k(ca) current in vestibular calyx terminals.
- Author
-
Meredith, Frances, Li, Gang, Rennie, Katherine, Meredith, Frances L, Li, Gang Q, and Rennie, Katherine J
- Subjects
- *
POSTNATAL care , *POTASSIUM , *CALCIUM , *VESTIBULAR apparatus , *AFFERENT pathway diseases , *HAIR cells , *INNER ear , *FIBERS , *PHYSIOLOGY - Abstract
Afferent innervation patterns in the vestibular periphery are complex, and vestibular afferents show a large variation in their regularity of firing. Calyx fibers terminate on type I vestibular hair cells and have firing characteristics distinct from the bouton fibers that innervate type II hair cells. Whole-cell patch clamp was used to investigate ionic currents that could influence firing patterns in calyx terminals. Underlying K(Ca) conductances have been described in vestibular ganglion cells, but their presence in afferent terminals has not been investigated previously. Apamin, a selective blocker of SK-type calcium-activated K(+) channels, was tested on calyx afferent terminals isolated from gerbil semicircular canals during postnatal days 1-50. Lowering extracellular calcium or application of apamin (20-500 nM) reduced slowly activating outward currents in voltage clamp. Apamin also reduced the action potential afterhyperpolarization (AHP) in whole-cell current clamp, but only after the first two postnatal weeks. K(+) channel expression increased during the first postnatal month, and SK channels were found to contribute to the AHP, which may in turn influence discharge regularity in calyx vestibular afferents. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
42. Development and organization of polarity-specific segregation of primary vestibular afferent fibers in mice.
- Author
-
Maklad, Adel, Kamel, Suzan, Wong, Elaine, and Fritzsch, Bernd
- Subjects
- *
HAIR cells , *CELL nuclei , *BRAIN stem , *NERVOUS system , *MAMMALS - Abstract
A striking feature of vestibular hair cells is the polarized arrangement of their stereocilia as the basis for their directional sensitivity. In mammals, each of the vestibular end organs is characterized by a distinct distribution of these polarized cells. We utilized the technique of post-fixation transganglionic neuronal tracing with fluorescent lipid soluble dyes in embryonic and postnatal mice to investigate whether these polarity characteristics correlate with the pattern of connections between the endorgans and their central targets; the vestibular nuclei and cerebellum. We found that the cerebellar and brainstem projections develop independently from each other and have a non-overlapping distribution of neurons and afferents from E11.5 on. In addition, we show that the vestibular fibers projecting to the cerebellum originate preferentially from the lateral half of the utricular macula and the medial half of the saccular macula. In contrast, the brainstem vestibular afferents originate primarily from the medial half of the utricular macula and the lateral half of the saccular macula. This indicates that the line of hair cell polarity reversal within the striola region segregates almost mutually exclusive central projections. A possible interpretation of this feature is that this macular organization provides an inhibitory side-loop through the cerebellum to produce synergistic tuning effects in the vestibular nuclei. The canal cristae project to the brainstem vestibular nuclei and cerebellum, but the projection to the vestibulocerebellum originates preferentially from the superior half of each of the cristae. The reason for this pattern is not clear, but it may compensate for unequal activation of crista hair cells or may be an evolutionary atavism reflecting a different polarity organization in ancestral vertebrate ears. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
43. The Configuration and Attachment of the Utricular and Saccular Maculae to the Temporal Bone.
- Author
-
Curthoys, Ian S., Uzun‐Coruhlu, Hilal, Wong, Chris C., Jones, Allan S., and Bradshaw, Andrew P.
- Subjects
- *
TEMPORAL bone , *INNER ear , *OTOLITHS , *VERTIGO , *NYSTAGMUS , *SEMICIRCULAR canals , *GUINEA pigs , *DISEASES - Abstract
High-resolution X-ray microtomography (micro-CT) was used to show the spatial configuration of the membranous labyrinth of the fixed guinea pig and human inner ear. Whole temporal bones were en bloc stained in 2% osmium tetroxide for 2 days or more to allow the osmium to attach to the membranes of the inner ear, and then scanned with a Skyscan 1172 micro-CT with highest resolution of 8 microns. The scans were segmented and reconstructed. The findings for guinea pigs and humans are similar. The saccular macula is closely attached to the curved medial wall of the temporal bone, but in both human and guinea pig the utricular macula is attached to the temporal bone only at the anterior region of the macula, and, as others have reported previously, much of the caudal area of the utricular macula is tenuously supported by a thin membrane, just above the dorsal margin of the stapes. This tenuous support may have important consequences for the sensing of forces by the utricular macula. Combining information from a dissected human horizontal canal with CT images allows an estimate of the orientation of the horizontal canal crista in human subjects, data which are necessary for treatment of benign paroyxsmal positional vertigo of the horizontal canal. The very high resolution achieved by micro-CT shows that reconstruction from inadequately sampled CT data produces images that are not anatomically correct, so that canal deformations and aplasias may appear to be present. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
44. Structural Diversity of Mitochondria.
- Author
-
Mannella, Carmen A.
- Subjects
- *
MITOCHONDRIA , *METABOLITES , *PROTEINS , *APOPTOSIS , *OXIDATIVE stress , *HYPOTHESIS - Abstract
Mitochondria display considerable structural diversity particularly in terms of the folding of the energy-transducing inner membrane. The hypothesis is forwarded that the topology of the mitochondrial inner membrane is not random but rather is a regulated cell parameter. Its effects on internal diffusion of metabolites and soluble proteins can influence such mitochondrial processes as ATP production and protein release during apoptosis. Progress toward understanding the factors that control mitochondrial inner-membrane curvature and dynamics (fusion and fission) is summarized, with a focus on remodeling events associated with apoptosis and oxidative stress. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
45. Expression of zebrafish aldh1a3 (raldh3) and absence of aldh1a1 in teleosts
- Author
-
Pittlik, Silke, Domingues, Susana, Meyer, Axel, and Begemann, Gerrit
- Subjects
- *
VITAMIN A , *CAROTENES , *TRETINOIN , *DERMATOLOGIC agents , *CHORDATA - Abstract
Abstract: The vitamin A-derived morphogen retinoic acid (RA) plays important roles during the development of chordate animals. The Aldh1a-family of RA-synthesizing enzymes consists of three members, Aldh1a1–3 (Raldh1–3), that are dynamically expressed throughout development. We have searched the known teleost genomes for the presence of Raldh family members and have found that teleost fish possess orthologs of Aldh1a2 and Aldh1a3 only. Here we describe the expression of aldh1a3 in the zebrafish, Danio rerio. Whole mount in situ hybridization shows that aldh1a3 is expressed during eye development in the retina flanking the optic stalks and later is expressed ventrally, opposite the expression domain of aldh1a2. During inner ear morphogenesis, aldh1a3 is expressed in developing sensory epithelia of the cristae and utricular macula and is specifically up-regulated in epithelial projections throughout the formation of the walls of the semicircular canals and endolymphatic duct. In contrast to the mouse inner ear, which expresses all three Raldhs, we find that only aldh1a3 is expressed in the zebrafish otocyst, while aldh1a2 is present in the periotic mesenchyme. During larval stages, additional expression domains of aldh1a3 appear in the anterior pituitary and the swim bladder. Our analyses provide a starting point for genetic studies to examine the role of RA in these organs and emphasize the suitability of the zebrafish inner ear in dissecting the contribution of RA signaling to the development of the vestibular system. [Copyright &y& Elsevier]
- Published
- 2008
- Full Text
- View/download PDF
46. The “wave turbopause”
- Author
-
Offermann, D., Jarisch, M., Schmidt, H., Oberheide, J., Grossmann, K.U., Gusev, O., Russell III, J.M., and Mlynczak, M.G.
- Subjects
- *
ATMOSPHERE , *MESOSPHERE , *CHEMOSPHERE , *LATITUDE - Abstract
Abstract: The “wave turbopause” is defined as the mesospheric altitude level where the temperature fluctuation field indicates a substantial increase in wave amplitudes in the vertical direction. The turbopause altitude is analyzed on the basis of four years of SABER data (2002–2005, Version 1.06). Substantial seasonal and latitudinal variations are found, with some interannual variability also present. Seasonal changes are annual at high latitudes, semi-annual at low latitudes, and a mixture of both at middle latitudes. Southern hemisphere data are similar as in the North if shifted by half a year. Latitudinal variations show a minimum in the tropics and two relative maxima at middle latitudes. The “wave turbopause” is found near to zero-wind lines or low-wind zones (zonal wind). It is compared to rocket and other measurements, and interesting similarities are obtained. The wave turbopause can also be found in the HAMMONIA GCM. A preliminary analysis shows results similar to those of the SABER measurements. [Copyright &y& Elsevier]
- Published
- 2007
- Full Text
- View/download PDF
47. Localization of anosmin-1a and anosmin-1b in the inner ear and neuromasts of zebrafish
- Author
-
Ernest, Sylvain, Guadagnini, Stéphanie, Prévost, Marie-Christine, and Soussi-Yanicostas, Nadia
- Subjects
- *
PROTEINS , *GENES , *DEVELOPMENTAL disabilities , *CELL migration , *AXONS - Abstract
Abstract: Anosmin-1, encoded by the KAL-1 gene, is the protein defective in the X-linked form of Kallmann syndrome. This human developmental disorder is characterized by defects in cell migration and axon target selection. Anosmin-1 is an extracellular matrix protein that plays a role, in vitro, in processes such as cell adhesion, neurite outgrowth, axon guidance, and axon branching. The zebrafish possesses two orthologues of the KAL-1 gene: kal1a and kal1b, which encode anosmin-1a and anosmin-1b, respectively. Previous in situ hybridization studies have shown that kal1a and kal1b mRNAs are expressed in undetermined cells of the inner ear but not in neuromast cells. Using specific antibodies against anosmin-1a and anosmin-1b, we report here that both proteins are expressed in sensory hair cells of the inner ear cristae ampullaris and the lateral line neuromasts. Accumulation of these proteins was observed mainly at the level of the hair bundle and also at the cell membrane. In neuromast hair cells, immunogold scanning electronmicroscopy demonstrated that anosmin-1a and anosmin-1b were present at the surface of the stereociliary bundle. In addition, anosmin-1a, but not anosmin-1b, was detected on the track of the ampullary nerve. This is the first report of anosmin-1 expression in sensory hair cells of the inner ear and lateral line, and along the ampullary nerve track. [Copyright &y& Elsevier]
- Published
- 2007
- Full Text
- View/download PDF
48. Mesospheric surf zone and temperature inversion layers in early November 1994
- Author
-
Oberheide, J., Liu, H.-L., Gusev, O.A., and Offermann, D.
- Subjects
- *
ROSSBY waves , *ATMOSPHERIC temperature , *ATMOSPHERE , *GRAVITY waves - Abstract
Abstract: Carbon monoxide, temperature, and potential vorticity data (November, 1994) from the cryogenic infrared spectrometers and telescopes for the atmosphere (CRISTA) experiment are used to analyze the relationship between the mesospheric surf zone in the winter hemisphere and simultaneously observed thermal inversions just above. The observed upward propagating planetary waves rapidly decay when they approach the critical wind line in the upper mesosphere and a distinct surf zone is formed between 60–75km. Above 85km, the planetary wave activity increases again revealing an out-of-phase behavior with the waves below. This is likely due to momentum forcing associated with breaking gravity waves that have been filtered by the stratospheric and lower mesospheric planetary waves. The abrupt vertical phase shift of the planetary waves thus induces a strong vertical geopotential curvature that is sufficiently large, through hydrostatic equilibrium, to invert the thermal structure around 80km. The CRISTA observations and their interpretation are consistent with simulations of the thermosphere–ionosphere–mesosphere-electrodynamics general circulation model (TIME-GCM) that was run for the same time period. Both the observation and the model results rather point to a more indirect, though essential, role of the gravity waves in the formation of the mesospheric inversion layers in early winter 1994. [Copyright &y& Elsevier]
- Published
- 2006
- Full Text
- View/download PDF
49. Atmospheric neutral temperature distribution at the mesopause altitude
- Author
-
Gusev, O., Kaufmann, M., Grossmann, K.-U., Schmidlin, F.J., and Shepherd, M.G.
- Subjects
- *
UPPER atmosphere , *ATMOSPHERE , *METEOROLOGICAL optics , *OCEANOGRAPHY - Abstract
Abstract: In November 1994 and August 1997 the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) instrument performed a global measurement (–) of infrared limb radiance from 4 to in the altitude range 6–180km. Using a non-local thermodynamic equilibrium (non-LTE) model that couples the collisional, radiative and photochemical processes, the kinetic temperature was recovered from emission for CRISTA-1 and -2 missions by direct assimilation of the integrated limb radiances between 72 and 120km. Falling sphere and airglow validation measurements at NASA/GSFC Wallops Flight Facility (WFF) and the Mesosphere–Thermosphere Emissions for Ozone Remote Sensing (METEORS) experiment at White Sands Missile Range were coordinated with CRISTA during the field campaign. The derived temperatures show good agreement with these rocket soundings, partial climatology obtained from Rayleigh scattering observations by Wind Imaging Interferometer (WINDII) on the Upper Atmosphere Research Satellite (UARS) and NRLMSISE-00 model. [Copyright &y& Elsevier]
- Published
- 2006
- Full Text
- View/download PDF
50. Vestibular primary afferent activity in an in vitro preparation of the mouse inner ear
- Author
-
Lee, Heung-Youp, Camp, Aaron J., Callister, Robert J., and Brichta, Alan M.
- Subjects
- *
ANIMALS , *MANIPULATIVE behavior , *BACTERIOPHAGES , *LYSOGENY - Abstract
Abstract: Most information on the properties of mammalian vestibular primary afferents has been obtained in deeply anesthetized animals, in vivo. Generally, non-human primates and larger rodents have been the species of choice. Investigations using smaller rodents, such as the laboratory mouse, have been limited despite the increasing availability of naturally occurring or engineered mutants that result in balance disorders. Furthermore, in vitro preparations of the intact peripheral vestibular apparatus are only available for non-mammalian vertebrates. To take advantage of the genetic/molecular advances available in mice and the utility of in vitro preparations that permit manipulations of the extracellular milieu, we developed an isolated mouse inner ear preparation with the attached eighth cranial nerve for electrophysiological recording. Intra-axonal recordings of background activity in vestibular primary afferents were obtained in a modified Ringer''s solution (0.25mMCa2+; 3.25mMMg2+) at 22°C. We also recorded afferent activity in the presence of neuroactive drugs known to affect various stages of the transduction cascade. These results, together with responses to sinusoidal mechanical deformation of the membranous ducts, showed that transduction mechanisms remain viable. Where possible, we also obtained results in vivo for comparison. In future, the in vitro mouse preparation will allow investigation of the effects of genetic manipulations and pharmacological agents on the intact peripheral vestibular apparatus. [Copyright &y& Elsevier]
- Published
- 2005
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.