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This study consists of a retrospective cohort study, a systematic review, and a meta-analysis which were separately conducted. This study aimed to investigate the prevalence of atlas arch defects, generate an evidence-based synthesis, and propose a common classi- fication system for the anterior and combined atlas arch defects. Atlas arch defects are well-corticated gaps in the anterior or posterior arch of the atlas. When both arches are involved, it is known as a combined arch defect. Awareness of these defects is essential for avoiding complications during surgical procedures on the upper spine. The prevalence of arch defects was investigated in an open-access OPC-Radiomics (Radiomic Biomarkers in Oropharyngeal Carcinoma) dataset comprising 606 head and neck computed tomography scans from oropharyngeal cancer patients. A systematic review and meta-analysis were performed to generate prevalence estimates of atlas arch defects and propose a classification system for the anterior and combined atlas arch defects. The posterior arch defect was found in 20 patients (3.3%) out of the 606 patients investigated. The anterior arch defect was not observed in any patient, while a combined arch defect was observed in one patient (0.2%). A meta-analysis of 13,539 participants from 14 studies, including the present study, yielded a pooled-posterior arch defect prevalence of 2.07% (95% confidence interval [CI], 1.22%-2.92%). The prevalences of anterior and combined arch defects were 0.00% (95% CI, 0.00%-0.10%) and 0.14% (95% CI, 0.04%-0.25%), respectively. The anterior and combined arch defects were classified into five subtypes based on their morphology and frequency. The present study showed that atlas arch defects were present in approximately 2% of the general population. For future studies, larger sample sizes should be used for studying arch defects to avoid the small-study effect and to predict the prevalence accurately. [ABSTRACT FROM AUTHOR]

Simple Summary: As a key element of the smooth muscle cell contractile apparatus, the actin cytoskeleton participates in the development of force by acting as a molecular track for the myosin cross bridge motor. At the same time, the actin cytoskeleton must transmit the force developed during contraction to the extracellular matrix and, thus, to neighboring cells. This propagation of force to the cell periphery and beyond is initiated in part on specifically localized cellular cortical actin filaments also involved in mechano-chemical transduction. During the contractile process itself and in response to extracellular structural and chemical alterations, the smooth muscle actin cytoskeletal remodels. This indicates that the cytoskeleton is a dynamic cellular organelle that adapts to the changes in cell shape and chemical cues. Current evidence connecting contractile function and mechano-transduction mechanisms to the plasticity of the vascular smooth muscle actin cytoskeleton is reviewed; we then describe new evidence for cytoskeletal remodeling in vascular smooth muscle cells. Here, using immunoelectron microscopy, we visualize the actin binding proteins filamin A, zyxin and talin in these cells and show that they participate in the cortical cell cytoskeletal alteration, thus supporting the premise that smooth muscle cell remodeling occurs during contraction. Considerable controversy has surrounded the functional anatomy of the cytoskeleton of the contractile vascular smooth muscle cell. Recent studies have suggested a dynamic nature of the cortical cytoskeleton of these cells, but direct proof has been lacking. Here, we review past studies in this area suggesting a plasticity of smooth muscle cells. We also present images testing these suggestions by using the technique of immunoelectron microscopy of metal replicas to directly visualize the cortical actin cytoskeleton of the contractile smooth muscle cell along with interactions by representative cytoskeletal binding proteins. We find the cortical cytoskeletal matrix to be a branched, interconnected network of linear actin bundles. Here, the focal adhesion proteins talin and zyxin were localized with nanometer accuracy. Talin is reported in past studies to span the integrin–cytoplasm distance in fibroblasts and zyxin is known to be an adaptor protein between alpha-actinin and VASP. In response to activation of signal transduction with the alpha-agonist phenylephrine, we found that no movement of talin was detectable but that the zyxin-zyxin spacing was statistically significantly decreased in the smooth muscle cells examined. Contractile smooth muscle is often assumed to have a fixed cytoskeletal structure. Thus, the results included here are important in that they directly support the concept at the electron microscopic level that the focal adhesion of the contractile smooth muscle cell has a dynamic nature and that the protein–protein interfaces showing plasticity are protein-specific. [ABSTRACT FROM AUTHOR]

Abstract: Filamin A (FLNa) is an actin-binding protein that cross-links F-actin into networks of orthogonally branched filaments. FLNa also directs the networks to integrins while responding to mechanochemical signaling pathways. Flexible, 160-nm-long FLNa molecules are tail-to-tail dimers, each subunit of which contains an N-terminal calponin homology (CH)/actin-binding domain connected by a series of 24 immunoglobulin (Ig) repeats to a dimerization site at their C-terminal end. Whereas the contribution of the CH domains to F-actin affinity is weak (apparent K a ~105), the binding of the intact protein to F-actin is strong (apparent K a ~108), suggesting involvement of additional parts of the molecule in this association. Indeed, previous results indicate that Ig repeats along FLNa contribute significantly to the strength of the actin filament interaction. In the current study, we used electron microscopy and three-dimensional reconstruction to elucidate the structural basis of the Ig repeat–F-actin binding. We find that FLNa density is clearly delineated in reconstructions of F-actin complexed either with a four-Ig-repeat segment of FLNa containing Ig repeat 10 or with immunoglobulin-like filamin A repeat (IgFLNa)10 alone. The mass attributable to IgFLNa10 lies peripherally along the actin helix over the N-terminus of actin subdomain 1. The IgFLNa10 interaction appears to be specific, since no other individual Ig repeat or fragment of the FLNa molecule examined, besides ones with IgFLNa10 or CH domains, decorated F-actin filaments or were detected in reconstructions. We conclude that the combined interactions of CH domains and the IgFLNa10 repeat provide the binding strength of the whole FLNa molecule and propose a model for the association of IgFLNa10 on actin filaments. [Copyright &y& Elsevier]

Abstract: Point mutations targeting muscle thin filament proteins are the cause of a number of cardiomyopathies. In many cases, biological effects of the mutations are well-documented, whereas their structural and mechanical impact on filament assembly and regulatory function is lacking. In order to elucidate molecular defects leading to cardiac dysfunction, we have examined the structural mechanics of two tropomyosin mutants, E180G and D175N, which are associated with hypertrophic cardiomyopathy (HCM). Tropomyosin is an α-helical coiled-coil dimer which polymerizes end-to-end to create an elongated superhelix that wraps around F-actin filaments of muscle and non-muscle cells, thus modulating the binding of other actin-binding proteins. Here, we study how flexibility changes in the E180G and D175N mutants might affect tropomyosin binding and regulatory motion on F-actin. Electron microscopy and Molecular Dynamics simulations show that E180G and D175N mutations cause an increase in bending flexibility of tropomyosin both locally and globally. This excess flexibility is likely to increase accessibility of the myosin-binding sites on F-actin, thus destabilizing the low-Ca2+ relaxed-state of cardiac muscle. The resulting imbalance in the on–off switching mechanism of the mutants will shift the regulatory equilibrium towards Ca2+-activation of cardiac muscle, as is observed in affected muscle, accompanied by enhanced systolic activity, diastolic dysfunction, and cardiac compensations associated with HCM and heart failure. [Copyright &y& Elsevier]

We have investigated the cellular characteristics, especially chromatin condensation and the basic nuclear protein profile, during spermiogenesis in the common tree shrew, Tupaia glis. Spermatids could be classified into Golgi phase, cap phase, acrosome phase, and maturation phase. During the Golgi phase, chromatin was composed of 10-nm and 30-nm fibers with few 50-nm to 60-nm knobby fibers. The latter were then transformed into 70-nm knobby fibers during the cap phase. In the acrosome phase, all fibers were packed into the highest-order knobby fibers, each about 80–100 nm in width. These chromatin fibers became tightly packed in the maturation phase. In a mature spermatozoon, the discoid-shaped head was occupied by the acrosome and completely condensed chromatin. H3, the core histone, was detected by immunostaining in all nuclei of germ cell stages, except in spermatid steps 15–16 and spermatozoa. Protamine, the basic nuclear protein causing the tight packing of sperm chromatin, was detected by immunofluorescence in the nuclei of spermatids at steps 12–16 and spermatozoa. Cross-immunoreactivity of T. glis H3 and protamine to those of primates suggests the evolutionary resemblance of these nuclear basic proteins in primate germ cells. [ABSTRACT FROM AUTHOR]

Saponins are secondary metabolite compounds that can be found in sea cucumbers (Holothuroidea spp.). However, little is known about how saponin‐rich extracts from Holothuria leucospilota can delay and prolong the lifespan of the whole organism. In this study, anti‐aging effects of H. leucospilota extracts were studied on Caenorhabditis elegans. NMR analysis revealed that body wall n‐butanol‐extract of H. leucospilota (BW‐BU) is saponin‐rich. BW‐BU extracts exhibited antioxidant activities by 2,2ʹ‐diphenyl‐2‐picrylhydrazyl assay (EC50 = 10.23 ± 0.12 mg/ml) and 2,2ʹ‐azino‐bis‐3‐ethylbenzthiazoline‐6‐sulphonic acid assay (EC50 = 3.91 ± 0.04 mg/ml). BW‐BU extracts increased lifespan of L4 and L1 C. elegans (5.92% and 15.76%, respectively), which also increased worm growth, stress resistance, and reduced biomarkers for aging. BW‐BU extracts activated DAF‐16 nuclear localization and upregulated daf‐16 and DAF‐16 target genes expression. Taken together, this study revealed the evidences on anti‐aging activities of saponin‐rich extracts from H. leucospilota, which can extend lifespan of C. elegans via daf‐16. Practical applications: In recent years, age‐associated chronic diseases have had a significant impact on quality of life. Many natural compounds exhibit anti‐aging activities, especially in sea cucumber, H. leucospilota. Our results indicated that H. leucospilota is good for health. Extracts from H. leucospilota contain a bioactive compound that can be potentially used to promote longevity and disease prevention in aging. [ABSTRACT FROM AUTHOR]

BACKGROUND: Saponins have been shown to possess many pharmacological properties, including altered fat metabolism. The black sea cucumber, Holothuria leucospilota, is a marine animal that contains a specialized organ called a Cuvierian tubule that produces and secrete the bioactive saponins into the tubules and body wall. Therefore, the aims of this study are to investigate the anti‐obesity effect of saponins extracted from body wall and Cuvierian tubules of H. leucospilota. RESULTS: The butanol extracts of H. leucospilota body wall and Cuvierian tubules containing high amounts of saponins significantly reduced fat deposition and triglyceride levels in Caenorhabditis elegans fed with 50 mmol L−1 glucose. Moreover, the saponin‐enriched extracts of H. leucospilota significantly restored the lifespan of 2% glucose‐fed worms (18.71%). Green fluorescence protein‐labeled sbp‐1 gene expression and nuclear translocation of daf‐16 were also significantly decreased in H. leucospilota treatment. The saponin‐enriched extracts downregulated the messenger RNA expressions of genes involved in fat storage and metabolism, including sbp‐1, cebp, and daf‐16 but upregulated the expression of nhr‐49 gene. CONCLUSION: Our results suggest that H. leucospilota‐derived saponins may mediate the reduction of glucose‐induced fat accumulation through sbp‐1, cebp, daf‐16 and nhr‐9 pathways. Therefore, the H. leucospilota extracts could be used as nutraceuticals for anti‐obesity prevention. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Duchene's muscular dystrophy (DMD) is an inherited disorder in an X-linked recessive manner. Lack of dystrophin causes progressive muscle degeneration. Dystrophin structurally connects to actin filaments at the N-terminus while the C-terminus interacts with an integral domain of the dystroglycan complex. Among the associated molecules, dystrobrevin acts as a modulator protein exerting dystrophin's function for strengthening the cell stability. Previous data has reported the delayed muscle degeneration following an overexpression of the dystrobrevin (dyb) gene in the DMD-phenotype C. elegans, whose dystrophin (dys) gene was missing. This finding indicates the role of a modulator protein, rather than dystrophin, to maintain the cell integrity. The present study aims to investigate the phenotypes of C. elegans, due to dyb- or dys-deficiency. When compared with the wild-type, the dyb-deficient worms exhibited uncoordinated locomotion and lysis of the muscular layer in the body wall and internal organs as well as those observed in the dys-deficient worms. The ultrastructure of both mutant worms appeared severe muscle degeneration, decrease of the mitochondria, and replacement of fibrotic tissue, particularly the dys-mutant which was even more severe. Additionally, a shorter lifespan was observed with a 17 % reduction (p < 0.05) in dyb-deficient worms and 27 % reduction (p < 0.05) in dys-deficient worms when compared to wild-type. It is speculated that dystrobrevin may stabilize the cell through interaction with other protein complexes at the plasma membrane while it also binds to dystrophin. Therefore, the loss of dystrobrevin is also sufficient to disrupt the signaling pathway and causes muscle degeneration. [ABSTRACT FROM AUTHOR]

Bin-Amphiphysin-Rvs (BAR) and Fes-CIP4 homology BAR (F-BAR) proteins generate tubular membrane invaginations reminiscent of the megakaryocyte (MK) demarcation membrane system (DMS), w hich provides membranes necessary for future platelets. The F-BAR protein PACSIN2 is one of the most abundant BAR/F-BAR proteins in platelets and the only one reported to interact with the cytoskeletal and scaffold protein filamin A (FlnA), an essential regulator of platelet formation and function. The FlnA-PACSIN2 interaction was therefore investigated in MKs and platelets. PACSIN2 associated with FlnA in human platelets. The interaction required FlnA immunoglobulin-like repeat 20 and the tip of PACSIN2 F-BAR domain and enhanced PACSIN2 F-BAR domain membrane tubulation in vitro. Most human and wild-type mouse p latelets had 1 to 2 distinct PACSIN2 foci associated with cell membrane GPIba, whereas Flna-null platelets had 0 to 4 or more foci. Endogenous PACSIN2 and transfected enhanced green fluorescent protein-PACSIN2 were concentrated in midstage wild-type mouse MKs in a well-defined invagination of the plasma membrane reminiscent of the initiating DMS and dispersed in the absence of FlnA binding. The DMS appeared less well defined, and platelet territories were not readily visualized in Fina-null MKs. We conclude that the FlnA-PACSIN2 interaction regulates m embrane tubulation in MKs and platelets and likely contributes to DMS formation. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • H. leucospilota extracts prevented degeneration of DA neurons and improved food-sensing behavior in 6-OHDA-induced C. elegans. • H. leucospilota extracts up-regulated cat-2 and sod-3 gene expressions in C. elegans PD model. • H. leucospilota extracts reduced α-synuclein aggregation and improved lipid deposition. • H. leucospilota extracts increased the lifespan of 6-OHDA-induced C. elegans. • NMR analysis revealed the major chemical components comprise terpenoids, steroids, saponins, and glycosides. Abstract Parkinson's disease (PD) is a well-known neurodegenerative disorder characterized by dopaminergic (DA) neuron loss and α-synuclein aggregation. Recent study revealed that the extracts from sea cucumber, Holothuroidea spp., exhibited neuroprotective and lifespan extension effects in Caenorhabditis elegans model. Interestingly, the black sea cucumber, Holothuria leucospilota, possesses body wall and a specialized organ called cuvierian tubules containing high amount of bioactive compounds. In this study, the neuroprotective effects of the body wall (BW) and cuvierian tubules (CT) from this sea cucumber against PD were evaluated using C. elegans as a model. H. leucospilota were extracted using ethanol (ET), ethyl acetate (EA), butanol (BU) and aqueous (AQ) fractions. Extracts from these fractions were used to treat the 6-OHDA-induced BZ555 and α-synuclein expressing NL5901 strains of C. elegans. Treatment with ET, EA, BU and AQ fractions of H. leucospilota extracts could significantly prevent degeneration of DA neurons in 6-OHDA-induced worms, improve food-sensing behavior mediated by DA neurons, and up-regulate cat-2 and sod-3 gene expressions. These results indicate the neuroprotective activity of the extracts which may be attributed to the anti-oxidant activity of the bioactive compounds. Moreover, α-synuclein aggregation was significantly reduced together with the recovery of lipid deposition upon the treatment with H. leucospilota extracts. In addition, treatment with H. leucospilota extracts was able to increase the lifespan of 6-OHDA-induced N2. NMR analysis revealed the major chemical components in the effective EA fractions were terpenoids, steroids, saponins, and glycosides. In summary, H. leucospilota extracts exhibited anti-Parkinson effect in both toxin-induced and transgenic C. elegans models of PD. Further study will be performed to elucidate the most effective anti-PD molecules which will lead to the development of anti-PD drug. [ABSTRACT FROM AUTHOR]

In the present study, the distribution and dynamic expression of serotonin and dopamine in the nervous system and ovary of the sea cucumber, Holothuria scabra, during different ovarian stages were investigated. We found that serotonin-immunoreactivity was more intense in the neurons and neuropils of the outer ectoneural part, the inner hyponeural part, and the wall of hyponeural canal of radial nerve cord during the mature stages of ovarian cycle, whereas dopamine-immunoreactivity was detected at a higher intensity in these tissues during the early stages. Both neurotransmitters were detected in the ectoneural part of the nerve ring. In the ovary, serotonin intensity was more intense in the cytoplasm of late oocytes, while dopamine-immunoreactivity was more intense in the early stages. The changes in the levels serotonin in the radial nerve cord and oocytes are incremental towards the late stages of ovarian maturation. In contrast, dopamine levels in the nervous tissues and oocytes were more intense in early stages and became decremental towards the late stages. These findings suggest that serotonin and dopamine may have opposing effects on ovarian development in this sea cucumber species. [ABSTRACT FROM AUTHOR]

The ends of coiled-coil tropomyosin molecules are joined together by nine to ten residue-long head-to-tail “overlapping domains”. These short four-chained interconnections ensure formation of continuous tropomyosin cables that wrap around actin filaments. Molecular Dynamics simulations indicate that the curvature and bending flexibility at the overlap is 10–20% greater than over the rest of the molecule, which might affect head-to-tail filament assembly on F-actin. Since the penultimate residue of striated muscle tropomyosin, Ser283, is a natural target of phosphorylating enzymes, we have assessed here if phosphorylation adjusts the mechanical properties of the tropomyosin overlap domain. MD simulations show that phosphorylation straightens the overlap to match the curvature of the remainder of tropomyosin while stiffening it to equal or exceed the rigidity of canonical coiled-coil regions. Corresponding EM data on phosphomimetic tropomyosin S283D corroborate these findings. The phosphorylation-induced change in mechanical properties of tropomyosin likely results from electrostatic interactions between C-terminal phosphoSer283 and N-terminal Lys12 in the four-chain overlap bundle, while promoting stronger interactions among surrounding residues and thus facilitating tropomyosin cable assembly. The stiffening effect of D283-tropomyosin noted correlates with previously observed enhanced actin–tropomyosin activation of myosin S1-ATPase, suggesting a role for the tropomyosin phosphorylation in potentiating muscle contraction. [ABSTRACT FROM AUTHOR]

Dynamin is a 96-kDa protein that has multiple oligomerization states that influence its GTPase activity. A number of different dynamin effectors, including lipids, actin filaments, and SH3-domain-containing proteins, have been implicated in the regulation of dynamin oligomerization, though their roles in influencing dynamin oligomerization have been studied predominantly in vitro using recombinant proteins. Here, we identify higher order dynamin oligomers such as rings and helices in vitro and in live cells using fluorescence lifetime imaging microscopy (FLIM). FLIM detected GTP- and actin-dependent dynamin oligomerization at distinct cellular sites, including the cell membrane and transition zones where cortical actin transitions into stress fibers. Our study identifies a major role for direct dynamin-actin interactions and dynamin's GTPase activity in the regulation of dynamin oligomerization in cells. [ABSTRACT FROM AUTHOR]

Influenza viruses exhibit striking variations in particle morphology between strains. Clinical isolates of influenza A virus have been shown to produce long filamentous particles while laboratory-adapted strains are predominantly spherical. However, the role of the filamentous phenotype in the influenza virus infectious cycle remains undetermined. We used cryo-electron tomography to conduct the first three-dimensional study of filamentous virus ultrastructure in particles budding from infected cells. Filaments were often longer than 10 microns and sometimes had bulbous heads at their leading ends, some of which contained tubules we attribute to M1 while none had recognisable ribonucleoprotein (RNP) and hence genome segments. Long filaments that did not have bulbs were infrequently seen to bear an ordered complement of RNPs at their distal ends. Imaging of purified virus also revealed diverse filament morphologies; short rods (bacilliform virions) and longer filaments. Bacilliform virions contained an ordered complement of RNPs while longer filamentous particles were narrower and mostly appeared to lack this feature, but often contained fibrillar material along their entire length. The important ultrastructural differences between these diverse classes of particles raise the possibility of distinct morphogenetic pathways and functions during the infectious process. [ABSTRACT FROM AUTHOR]

Abstract: Immunolocalization by using rabbit polyclonal antibody against APGWamide demonstrated that there was APGWamide immunoreactivity (APGW-ir) in the varicosed nerve fibers in the capsule, connective tissue and trabeculae of the testis whereas there was no APGW-ir in the ovary of sexually mature broodstocks of Haliotis asinina. In vivo bioassay, by injecting APGWamide into foot muscle of mature males and females (age over 24 months), showed that most males (87.50%) injected with 200 μl of 10−3 M APGWamide (170 μg APGWamide/animal) could be induced to spermiate whereas fewer males (43.75%) injected with 200 μl of 10−6 M APGWamide (0.17 μg APGWamide/animal) could spermiate. Following injection with 10−3 M, 53% of males spawned within 3 to 4 h, while the remaining males spawned within 2 to 3 h. The former tended to release more sperm at the range of 1.04 to 2×109, and the latter at the range 3.62×107 to 2.07×108 cells, respectively, and that the sperm of the former group appeared to be more motile. Following the injection of 10−6 M, all inducible males spawned within 2–3 h, and 43% of spawned males have sperm around 2×109, while 57% have fewer sperm number ranging from 2.75×107 to 9.94×108 cells. In contrast to males, none of the mature females with ripen ovary could be induced to ovulate. These data suggest that APGWamide is an important signaling molecule that plays a role in the male reproductive process that could be used to induce spermiation. [Copyright &y& Elsevier]

NG-related neuropeptide is a myoactive neuropeptide identified in deuterostome invertebrates. Recent studies indicated that in sea cucumbers NG-related neuropeptide can stimulate muscle contraction and is involved in reproduction, including oocyte maturation and gamete spawning. In the present study, we first characterized the NG-related neuropeptide precursor, named cubifrin in Holothuria scabra and further investigated its effect on spawning. The deduced amino acid sequence of the neuropeptide precursor transcript provided five copies of two different mature sequences and were designated as cubifrin-Y and cubifrin-F based on C-terminal amino acid sequences of NGIWYamide and NGIWFamide. Interestingly, physiological bioassay demonstrated that the newly identified cubifrin-F was more potent in stimulating spawning with about 70% success rate, than cubifrin-Y that could stimulate only 10% spawning, compared with the control group. The in situ hybridization showed intense expression of cubifrin transcript within the wall of the ovarian tubule at late ovarian stages, suggesting that cubifrin was produced locally and stimulated spawning by causing contraction of the wall of ovarian tubule. Taken together, gained knowledge provided important insight into spawning mechanisms which could be applied by using these cubifrin amides to stimulate spawning of broodstocks for seed and larval productions in aquaculture of this sea cucumber species. • The cubifrin neuropeptide precursor in H. scabra was newly identified to be NGIWYamide and NGIWFamide. • The newly identified cubifrin-F was more potent in stimulating spawning. • The in situ hybridization showed intense expression of cubifrin transcript within ovarian tubule wall of late stage ovary. • These cubifrins could be used to stimulate of spawning of H. scabra for seed and larval productions in aquaculture. [ABSTRACT FROM AUTHOR]