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Pedipalps – chelate 'pincers' as the second pair of prosomal appendages – are a striking feature of scorpions and are employed in varied biological functions. Despite the distinctive morphology and ecological importance of these appendages, their anatomy remains underexplored. To rectify this, we examined the pedipalps of the Australian black rock scorpion, Urodacus manicatus , using a multifaceted approach consisting of microcomputed tomography, scanning electron microscopy, energy dispersive X-ray spectroscopy, and live pinch force measurements. In doing so, we document the following aspects of the pedipalps: (1) the musculature in three dimensions; (2) the cuticular microstructure, focusing on the chelae (tibial and tarsal podomeres); (3) the elemental construction of the chelae teeth; and (4) the chelae pinch force. We recognise 25 muscle groups in U. manicatus pedipalps, substantially more than previously documented in scorpions. The cuticular microstructure – endo-, meso-, and exocuticle – of U. manicatus pedipalps is shown to be similar to other scorpions and that mesocuticle reinforces the chelae for predation and burrowing. Elemental mapping of the chelae teeth highlights enrichment in calcium, chlorine, nickel, phosphorus, potassium, sodium, vanadium, and zinc, with a marked lack of carbon. These elements reinforce the teeth, increasing robustness to better enable prey capture and incapacitation. Finally, the pinch force data demonstrate that U. manicatus can exert high pinch forces (4.1 N), further highlighting the application of chelae in subduing prey, as opposed to holding prey for envenomation. We demonstrate that U. manicatus has an array of adaptions for functioning as a sit-and-wait predator that primarily uses highly reinforced chelae to process prey. [ABSTRACT FROM AUTHOR]

Aim of the study. The permanent exchanges between the body and the environment tend to generally disturb homeostasis, particularly the hydroelectrolytic homeostasis. The analysis of the renin-angiotensin system reveals its multiple facets of physiological, physiopathological and pharmacological interest and at the same time highlights the fact that it represents a major component of biomedical scientific research. Material and methods. We studied the renin-angiotensin system action on utero-tubal motility with the help of certain substances that affect its metabolism and the affinity of its receptors. Results 1. Angiotensin II induces a contractile effect dependent on the calcium concentration in the cytosol. 2. In extracellular administration, angiotensin II has an oxytocin effect and an AT1 receptor binding effect. 3. In intracellular administration, the effect of Ang II is completely dependent on the activation of intracellular AT1 receptors. 4. Paradoxically, pretreatment with candesartan does not reduce muscle contractility to electric field stimulation but significantly stimulates it. Electrically stimulated contraction is significantly potentiated by Ang II administration, even under conditions of AT1 receptor blockade with candesartan. Conclusions: There is no mediation of the presence or synthesis of angiotensin II dependent on the presence of the angiotensin converting enzyme. This suggests that the administration of converting enzyme inhibitors in the case of pregnancy associated with hypertension could be without risk, since it does not affect uterine contractility. The physiological consequences of our results need new experimental and clinical studies in order to validate our hypothesis and draw recommendations to be clinically applied.

The article explores the effects of the renin-angiotensin system on utero-tubal motility. It found that angiotensin II induces contractions in uterine smooth muscle and can enhance electrically stimulated contractions. The authors suggest that using converting enzyme inhibitors during pregnancy for hypertension may not affect uterine contractions. However, more research is needed to validate these findings and provide clinical recommendations. The article also discusses the effects of electrical stimulation and pharmacological substances on uterine contractions, as well as the role of angiotensin and oxytocin in this process. It concludes that further research is necessary to fully understand the physiological implications of these findings. [Extracted from the article]

The purpose of this study was to explore the differentially expressed genes related to fat metabolism in muscle tissue of Tan lambs at different ages under the house-feeding mode. Twelve Tantan sheep with similar body condition were selected as the study objects, and three Tantan sheep with similar body weight were selected for slaughter at two-month-old and ix-month-old, respectively, and the longissimus dorsi muscle and biceps femoris muscle were taken. Transcriptome sequencing of the longissimus dorsi muscle was performed by Illumina to screen for genes related to fat metabolism. The results showed that a total of 146 differentially expressed genes were screened from the biceps femoris muscle of six-month-old and two-month-old Tan lambs, of which 69 genes were up-regulated and 77 genes were down-regulated. The differentially expressed genes were enriched in 40 GO entries, mainly in biological processes such as the regulation of endotheEal apoptosis, carboxylic acid metabolism and epithelial apoptosis. KEGG was significantly enriched in four pathways, and the pathways closely related to fat metabolism were PPAR signaling pathway and adipocytokine signaling pathway. According to transcriptome analysis, AJMGPTLA, FASN, and CPT1A genes were associated with fat metabolism. A total of 1 418 differentially expressed genes were screened in the longissimus dorsi muscle of six-month-old and two-month-old Tan lambs, of which 774 genes were up-regulated and 644 genes were down-regulated. GO enrichment was mainly reflected in cellcell adhesion, cell-cell adhesion of a single organism and cell adhesion of a single organism, and KEGG was significantly enriched in 18 pathways, among which PPAR signaling pathway and fatty acid metabolism pathway were closely related to fat metabolism. LEP, IGF2, and FABP3 genes were associated with fat metabolism according to transcriptome data. The results showed that ANGPTLA, FASN, and CPTLA genes regulated the fat metabolism of biceps femoris muscle in lambs at different months of age, while the LEP, IGF2, and FABP genes play a regulatory role in fat metabolism in the longissimus dorsi muscle. [ABSTRACT FROM AUTHOR]

Molluscs often possess complex calcified elements in addition to the shell, but how these elements function and relate to other tissues is often poorly understood. Dorid nudibranchs typically possess innumerable calcareous spicules arranged in complex networks. To describe how these spicules interact with muscles and connective tissue, we reconstructed tomographic digital models using serial sections and synchrotron micro-computed tomography. In two species with dramatically different spicule network morphologies, musculature was divided into a dorsal layer of crossed fibres, a ventral layer of branching radial fibres, and scattered dorsoventral fibres in between. These two species differed in the size of their dorsal tubercles, which was reflected in the organization of dorsal musculature, and in the amount and organization of connective tissue. In Platydoris sanguinea Bergh, 1905, dense mats of spicules sandwiched a layer of connective tissue with fewer spicules and muscle insertions only onto the ventral spicules. In Cadlina luteomarginata MacFarland, 1966, thick tracts of spicules are surrounded by a sheath of connective tissue. Muscles surround and insert into the dorsal tubercle spicule layer. Thus, both species appear to use the spicule network for muscle antagonism and transfer of motion, but the different arrangement of elements suggests that they use this skeleton in quite different ways.

Canine hip dysplasia (CHD) is among the most common orthopedic diseases in dogs. In large breed dogs, increase in pelvic muscle mass is associated with decreased incidence of CHD. The aim of this study was to characterize individual hip joint muscle contributions to the pelvic muscle mass, and evaluate the suitability of the parameters previously shown to identify large-breed dogs predisposed to CHD to small to medium sized dogs. Fifteen cadavers of mixed-breed dog (age range, 1-4 years; body weight range 6-28 kg) were used. Twenty-four muscles, directly acting on the hip joint were identified during dissection. Each muscle was dissected from surrounding tissues and weighed. These muscles were divided into five groups based on their innervation. The hip joint and surrounding bone were visually examined for cartilage damage and articular osterophyte formation. The hemipelvic muscle weight, as a percentage of body weight, was 4.85%±0.81. The contributions of the muscles innervated by the sciatic, femoral, obturator and the gluteal nerves were 35.73%±1.21, 28.45%±1.49, 21.28%±0.73 and 14.54%±1.17 of the entire pelvic muscle mass, respectively. Based on the previously published criteria for large breed dogs, as many as 67% of dogs in this study would have been expected to be predisposed to CHD; however, all the hip joints of these dogs were free of pathology. It was concluded that hemipelvic muscle mass relationship parameters applied to large breed dogs predisposed to CHD might be unsuitable for small to medium size dogs. [ABSTRACT FROM AUTHOR]

Four genera of the Boidae family are found in Brazil: Eunectes, Corallus, Epicrates, and Boa. Male copulatory organs in snakes are located inside the tail and are called hemipenes. They are double structures in an inverted position that are exposed during copulation. This study describes the macroscopic and histological aspects of hemipenes in Boidae snakes. One Boa constrictor, three Epicrates cenchria, one Corallus hortulanus hemipenes, and one fragment of the muscular retractor penis magnus (m. retractor penis magnus) from Eunectes murinus were included in this study. The structures were evaluated macroscopically and photo‐documented using a stereo microscope. Tissue fragments were included in glycol methacrylate plastic resin, cut into 3‐μm‐thick slices, and stained with 1% toluidine blue for microscopic evaluation. The macroscopic analysis showed that the arrangement and diameter occupied by the m. retractor penis magnus in the hemipenis and the internal and external cavernous bodies differ between species. The histological analysis showed that the hemipenis of B. constrictor, E. cenchria, and C. hortulanus has stratified epithelium in the external portion supported by dense connective tissue with blood vessels and muscle tissue. Although the literature reports the presence of skeletal musculature in the hemipenis, striated musculature with a centrally located nucleus in the fibre bundle, typical of cardiac musculature in mammals, was observed in the studied species. [ABSTRACT FROM AUTHOR]

Laternula elliptica (P. P. King, 1832) is the sole representative of the anomalodesmatan family Laternulidae and the largest bivalve in the Antarctic and Subantarctic. A keystone species of the regional benthic communities, it has reached model status, having been studied in hundreds of scientific works across many biological disciplines. In contrast, its anatomy has remained poorly known, with prior published data limited to partial descriptions based on chemically preserved specimens. Based on observations of aquarium-maintained living animals at the Brazilian Comandante Ferraz Antarctic Station, gross-morphological dissections, and histological sectioning, the comparative anatomy, functional morphology, and aspects of behavior of L. elliptica are described and discussed. Special focus is placed on the pallial organs (including elucidation of cleansing and feeding sorting mechanisms in the mantle cavity) and the musculature. Among the noteworthy findings are the presence of well-developed siphons furnished with sensory tentacles at its tips, some of which bearing eyes; large, folded gills and labial palps capable of sorting the material entering the mantle cavity; an inter-chamber communication in the posterior region of the mantle cavity; an ample ventral mantle fusion with an anterior pedal gape; the absence of a 4th pallial opening; and the absence of a ligamental lithodesma in adult specimens. This study reevaluates the available anatomical data in the literature, both supplementing and correcting previously published accounts. [ABSTRACT FROM AUTHOR]

The osteology, neuroanatomy, and musculature are known for most primary clades of turtles (i.e., "families"), but knowledge is still lacking for one particular clade, the Carettochelyidae. Carettochelyids are represented by only one living taxon, the pig-nosed turtle Carettochelys insculpta. Here, we use micro-computed tomography of osteological and contrast-enhanced stained specimens to describe the cranial osteology, neuroanatomy, circulatory system, and jaw musculature of Carettochelys insculpta. The jaw-related myology is described in detail for the first time for this taxon, including m. zygomaticomandibularis, a muscular unit only found in trionychians. We also document a unique arterial pattern for the internal carotid artery and its subordinate branches and provide an extensive list of osteological ontogenetic differences. The present work provides new insights into the craniomandibular anatomy of turtles and will allow a better understanding of the evolutionary history of the circulatory system of trionychians and intraspecific variation among turtles., (© 2024 The Authors. The Anatomical Record published by Wiley Periodicals LLC on behalf of American Association for Anatomy.)

Pyritization of soft tissues of invertebrates is rare in the fossil record. In New York State, it occurs in black shales of the Lorraine Group (Late Ordovician), the best-known example of which is Beecher's Trilobite Bed. Exceptional preservation at the quarry where this bed is exposed allowed detailed examination of trilobite and ostracod soft-tissue anatomy. Here, we present the first example of a eurypterid (sea scorpion) currently ascribed to Carcinosomatidae from this deposit that also preserves the first evidence for mesosomal musculature in eurypterids. This specimen demonstrates that eurypterid musculature can be preserved in pyrite and evidences the oldest example of euchelicerate muscles within the fossil record. Sulfur isotope data illustrate that pyrite rapidly replicated muscle tissue in the early burial environment, prior to the pyritization of biomineralized exoskeleton and cuticular trilobite limbs. This discovery therefore expands the limited fossil record of euchelicerate musculature, while extending the taphonomic scope for preservation of detailed internal structures, more broadly, within arthropods.

Abstract Background Monogeneans, in general, show a range of unique adaptations to a parasitic lifestyle, making this group enormously diverse. Due to their unique biological properties, diplozoid monogeneans represent an attractive model group for various investigations on diverse biological interactions. However, despite numerous studies, there are still gaps in our knowledge of diplozoid biology and morphofunctional adaptations. Results In this study, we provide a comprehensive microscopic analysis of systems/structures involved in niche searching, sensing and self-protection against the host environment, and excretory/secretory processes in Eudiplozoon nipponicum. Freeze-etching enabled us to detect syncytium organisational features not visible by TEM alone, such as the presence of a membrane subjacent to the apical plasma membrane (separated by a dense protein layer) and a lack of basal plasma membrane. We located several types of secretory/excretory vesicles and bodies, including those attached to the superficial membranes of the tegument. Giant unicellular glands were seen accumulating predominantly in the apical forebody and hindbody haptor region. Muscle layer organisation differed from that generally described, with the outer circular and inner longitudinal muscles being basket-like interwoven by diagonal muscles with additional perpendicular muscles anchored to the tegument. Abundant muscles within the tegumentary ridges were detected, which presumably assist in fixing the parasite between the gill lamellae. Freeze-etching, alongside transmission electron and confocal microscopy with tubulin labelling, enabled visualisation of the protonephridia and nervous system, including the peripheral network and receptor innervation. Three types of receptor were identified: 1) uniciliated sensory endings with a subtle (or missing) tegumentary rim, 2) obviously raised uniciliated receptors with a prominent tegumentary rim (packed with massive innervation and muscles) and 3) non-ciliated papillae (restricted to the hindbody lateral region). Conclusions This study points to specific morphofunctional adaptations that have evolved in diplozoid monogeneans to confront their fish host. We clearly demonstrate that the combination of different microscopic techniques is beneficial and can reveal hidden differences, even in much-studied model organisms such as E. nipponicum.

Stem cells play key roles in development, tissue homeostasis, regeneration, ageing and diseases. Comprehensive reviews on stem cells are available for the determinately growing mammals and insects and some lower invertebrates like hydra but are rare for larger, indeterminately growing invertebrates that can live for many decades. This paper reviews the cytology, function and dynamics of stem and progenitor cells in the decapod crustaceans, a species‐rich and ecologically and economically important animal group that includes mainly indeterminate growers but also some determinate growers. Further advantages of decapods for stem cell research are almost 1000‐fold differences in body size and longevity, the regeneration of damaged appendages and the virtual absence of age‐related diseases and tumours in the indeterminately growing species. The available data demonstrate that the Decapoda possess a remarkable variety of structurally and functionally different stem cells in embryos and larvae, and in the epidermis, musculature, haematopoietic tissue, heart, brain, hepatopancreas, olfactory sense organs and gonads of adults. Some of these seem to be rather continuously active over a lifetime but others are cyclically activated and silenced in periods of days, weeks and years, depending on the specific organ and function. Stem cell proliferation is triggered by signals related to development, moulting, feeding, reproduction, injury, infection, environmental enrichment and social status. Some regulatory pathways have already been identified, including the evolutionarily conserved GATA‐binding and runt‐domain transcription factors, the widespread neurotransmitter serotonin, the arthropod‐specific hormone 20‐hydroxyecdysone and the novel astakine growth factors. Knowledge of stem cells in decapods primarily refines our picture on the development, growth and maintenance of tissues and organs in this animal group. Cultured decapod stem cells have good potential for toxicity testing and virus research with practical relevance for aquaculture. Knowledge of stem cells in decapods also broadens our understanding of the evolution of stem cells and regeneration in the animal kingdom. The stem cells of long‐lived, indeterminately growing decapods may hold the key to understanding how stem and progenitor cells function into old age without adverse side effects, possibly evoking new ideas for the development of anti‐ageing and anti‐cancer treatments in humans. [ABSTRACT FROM AUTHOR]

Simple Summary: Click beetles are well-known for the specialized thoracic structure, which they can click to thrust themselves into the air and to right themselves. Several aspects of their jumping mechanism were still not entirely clear prior to this study. We utilized traditional dissection, 3D virtual dissection, and high-speed filming techniques to investigate the functional morphology of their thorax. Our results show several new insights into their extraordinary clicking and jumping mechanisms. We investigated and described the thoracic structures, jumping mechanism, and promesothoracic interlocking mechanism of the click beetle Campsosternus auratus (Drury) (Elateridae: Dendrometrinae). Two experiments were conducted to reveal the critical muscles and sclerites involved in the jumping mechanism. They showed that M2 and M4 are essential clicking-related muscles. The prosternal process, the prosternal rest of the mesoventrite, the mesoventral cavity, the base of the elytra, and the posterodorsal evagination of the pronotum are critical clicking-related sclerites. The destruction of any of these muscles and sclerites resulted in the loss of normal clicking and jumping ability. The mesonotum was identified as a highly specialized saddle-shaped biological spring that can store elastic energy and release it abruptly. During the jumping process of C. auratus, M2 contracts to establish and latch the clicking system, and M4 contracts to generate energy. The specialized thoracic biological springs (e.g., the prosternum and mesonotum) and elastic cuticles store and abruptly release the colossal energy, which explosively raises the beetle body in a few milliseconds. The specialized trigger muscle for the release of the clicking was not found; our study supports the theory that the triggering of the clicking is due to the building-up of tension (i.e., elastic energy) in the system. [ABSTRACT FROM AUTHOR]

Abstract The jaw apparatus in several annelid families represents a powerful tool for systematic approaches and evolutionary investigations. Nevertheless, for several taxa, this character complex has scarcely been investigated, and complete comparative analyses of all annelid jaws are lacking. In our comprehensive study, we described the fine structure of the jaw apparatus and the ventral pharyngeal organ (VPO) in Histriobdella homari – a minute ectocommensal of lobsters putatively belonging to the Eunicida – using different comparative morphological approaches, including SEM, TEM, CLSM and subsequent 3D reconstruction. The H. homari jaw apparatus is composed of ventral paired mandibles and dorsal symmetrical maxillae consisting of numerous dental plates, ventral carriers and an unpaired dorsal rod, and the general assemblage and arrangement of the different parts are highly comparable to those of other eunicid families. The jaw ultrastructure of histriobdellids resembles that of the families Dorvilleidae and (juvenile) Onuphidae. Furthermore, our data reveal that in the process of development of the jaw apparatus, the mandibles, maxillae II and unpaired dorsal rod are formed first, and the remaining maxillae and ventral carriers appear later. Notably, the muscular apparatus differs from that in Dorvilleidae and Onuphidae in terms of the number and arrangement of muscle fibers encompassing the jaws – not only because of the very small size of Histriobdella but also because histriobdellid maxillary protraction occurs due to straightening of the dorsal rod and thus requires a different muscular scaffold. Based on our investigations, the arrangement of the muscular apparatus of the jaws, the presence of paired ventral carriers and the dorsal rod, and the morphology of the ventral pharyngeal organ represent a histriobdellid autapomorphy. Our datasets form a basis for further comparative analyses to elucidate the evolution of Eunicida and jaw-bearing Annelida.

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Abstract Background The structure of the lingua of birds frequently gives some clue to the principal diet and manner of feeding of the species. The lingua is suitably modified for this purpose or does not intent the present work to understand it. The anatomical details of the lingual apparatus and their associated epidermal, musculature, and osteological elements of Indian doves (Aves: Columbidae) Eurasian collared dove (Streptopelia decaocto) and laughing dove (Stigmatopelia senegalensis) with comparison are lacking in the literature. Results A total of eight (n = 8/species) freshly preserved adult specimens with natural mortalities from Central Saurashtra, Western India, were examined. All the morphological features of species were observed in living as well as in preserved with the help of a pair of binoculars in the field and in the laboratory with stereo zoom dissecting microscope and camera lucida which are used for illustrations. The anatomical study includes the epidermal structures of the buccal region, lingua, apparatus hyobranchialis, and lingual muscles in relation to feeding behaviors and food. All these aspects are correlated with the food habits and finally with the muscles which bring about the suitable movements of the lingua. Conclusion The lingua in Eurasian collared dove (Streptopelia decaocto) and laughing dove (Stigmatopelia senegalensis) studied here does not exhibit any wide variations in appearance as such. Although the comparison between the two dove species is reflected, a relation in diverse food habits and all the morphological variables do not reflect allometric consequences of selection on body size. Finally, the assumption appears intuitively right between morphology, food habits, and variable size of the food items and clears various microhabitat choices in adverse conditions.

Abstract Background The aquatic Acari are known as water mites and occupy a wide range of habitats. The freshwater mites, Unionicola aegyptiaca, were collected from the freshwater mussel, Caelatura aegyptiaca, River Nile, Sohag, Egypt. The present paper focuses on the structure of the cuticle and musculature of freshwater mite, U. aegyptiaca. Results Histologically, the cuticle consists of two main layers: epicuticle and procuticle. The latter divided into two sublayers, exocuticle (exo) and endocuticle (en). The musculature of the present species, U. aegyptiaca, is divided into three regions: gnathosoma, idiosoma, and legs. The muscles of the body are classified according to their position and function. Conclusion Details of muscles of gnathosoma, coxal epimerae, genital field, and legs were all described and discussed. The cuticle and musculature of U. aegyptiaca were studied by using the light microscope, and the drawings were down with the help of a camera Lucida. It is likely to note that the cuticle and musculature of freshwater mite, U. aegyptiaca, were described and discussed for the first time in Egypt.

Annelids are predominantly found along with the seafloor, but over time have colonized a vast diversity of habitats, such as the water column, where different modes of locomotion are necessary. Yet, little is known about their potential muscular adaptation to the continuous swimming behaviour required in the water column. The musculature and motility were examined for five scale worm species of Polynoidae (Aphroditiformia, Annelida) found in shallow waters, deep sea or caves and which exhibit crawling, occasional swimming or continuous swimming, respectively. Their parapodial musculature was reconstructed using microCT and computational three-dimensional analyses, and the muscular functions were interpreted from video recordings of their locomotion. Since most benthic scale worms are able to swim for short distances using body and parapodial muscle movements, suitable musculature for swimming is already present. Our results indicate that rather than rearrangements or addition of muscles, a shift to a pelagic lifestyle is mainly accompanied by structural loss of muscle bundles and density, as well as elongation of extrinsic dorsal and ventral parapodial muscles. Our study documents clear differences in locomotion and musculature among closely related annelids with different lifestyles as well as points to myoanatomical adaptations for accessing the water column.

Cimicidae are well-known for traumatic insemination, and males pierce females with their parameres and transfer sperm through them. The shape of parameres is relatively stable in the family, but in some genera, the paramere is elongated, appearing less resistant against lateral deflection. To understand the mechanical limitations of the paramere, we studied its penetration mechanics of the common bed bug, Cimex lectularius . We examined the post-abdominal morphology, paramere geometry and material properties and conducted breaking stress experiments on the paramere under wet and dry conditions. Mechanical property gradients are present with the paramere tip as the stiffest region and the base as the most flexible one. These mechanical properties relate to the presence of Ca, Zn and Si. The basal wing-shaped structure is flexible, enabling it to interlock with the anal region during mating. The paramere is slightly twisted; the tip region is circular in cross-section, and the geometry of the rest is rather complex. In the mechanical tests, wet parameres mainly buckled, while dried parameres broke off. The level of structural failures depended on directions from which the compression forces were applied. Structural, material and mechanical strengthening mechanisms preventing the paramere from mechanical failure are discussed.

This paper is the second in a two-part series that charts the evolution of appendicular musculature along the mammalian stem lineage, drawing upon the exceptional fossil record of extinct synapsids. Here, attention is focused on muscles of the hindlimb. Although the hindlimb skeleton did not undergo as marked a transformation on the line to mammals as did the forelimb skeleton, the anatomy of extant tetrapods indicates that major changes to musculature have nonetheless occurred. To better understand these changes, this study surveyed the osteological evidence for muscular attachments in extinct mammalian and nonmammalian synapsids, two extinct amniote outgroups, and a large selection of extant mammals, saurians, and salamanders. Observations were integrated into an explicit phylogenetic framework, comprising 80 character-state complexes covering all muscles crossing the hip, knee, and ankle joints. These were coded for 33 operational taxonomic units spanning >330 Ma of tetrapod evolution, and ancestral state reconstruction was used to evaluate the sequence of muscular evolution along the stem lineage from Amniota to Theria. The evolutionary history of mammalian hindlimb musculature was complex, nonlinear, and protracted, with several instances of convergence and pulses of anatomical transformation that continued well into the crown group. Numerous traits typically regarded as characteristically "mammalian" have much greater antiquity than previously recognized, and for some traits, most synapsids are probably more reflective of the ancestral amniote condition than are extant saurians. More broadly, this study highlights the utility of the fossil record in interpreting the evolutionary appearance of distinctive anatomies., (© 2023 American Association for Anatomy.)

This paper is the first in a two-part series that charts the evolution of appendicular musculature along the mammalian stem lineage, drawing upon the exceptional fossil record of extinct synapsids. Here, attention is focused on muscles of the forelimb. Understanding forelimb muscular anatomy in extinct synapsids, and how this changed on the line to mammals, can provide important perspective for interpreting skeletal and functional evolution in this lineage, and how the diversity of forelimb functions in extant mammals arose. This study surveyed the osteological evidence for muscular attachments in extinct mammalian and nonmammalian synapsids, two extinct amniote outgroups, and a large selection of extant mammals, saurians, and salamanders. Observations were integrated into an explicit phylogenetic framework, comprising 73 character-state complexes covering all muscles crossing the shoulder, elbow, and wrist joints. These were coded for 33 operational taxonomic units spanning >330 Ma of tetrapod evolution, and ancestral state reconstruction was used to evaluate the sequence of muscular evolution along the stem lineage from Amniota to Theria. In addition to producing a comprehensive documentation of osteological evidence for muscle attachments in extinct synapsids, this work has clarified homology hypotheses across disparate taxa and helped resolve competing hypotheses of muscular anatomy in extinct species. The evolutionary history of mammalian forelimb musculature was a complex and nonlinear narrative, punctuated by multiple instances of convergence and concentrated phases of anatomical transformation. More broadly, this study highlights the great insight that a fossil-based perspective can provide for understanding the assembly of novel body plans., (© 2023 American Association for Anatomy.)

Background: Obstructive sleep apnea/hypopnea syndrome (OSAHS) is a prevalent condition affecting a substantial portion of the global population, with its prevalence increasing over the past 2 decades. OSAHS is characterized by recurrent upper airway (UA) closure during sleep, leading to significant impacts on quality of life and heightened cardiovascular and metabolic morbidity. Despite continuous positive airway pressure (CPAP) being the gold standard treatment, patient adherence remains suboptimal due to various factors, such as discomfort, side effects, and treatment unacceptability., Objective: Considering the challenges associated with CPAP adherence, an alternative approach targeting the UA muscles through myofunctional therapy was explored. This noninvasive intervention involves exercises of the lips, tongue, or both to improve oropharyngeal functions and mitigate the severity of OSAHS. With the goal of developing a portable device for home-based myofunctional therapy with continuous monitoring of exercise performance and adherence, the primary outcome of this study was the degree of completion and adherence to a 4-week training session., Methods: This proof-of-concept study focused on a portable device that was designed to facilitate tongue and lip myofunctional therapy and enable precise monitoring of exercise performance and adherence. A clinical study was conducted to assess the effectiveness of this program in improving sleep-disordered breathing. Participants were instructed to perform tongue protrusion, lip pressure, and controlled breathing as part of various tasks 6 times a week for 4 weeks, with each session lasting approximately 35 minutes., Results: Ten participants were enrolled in the study (n=8 male; mean age 48, SD 22 years; mean BMI 29.3, SD 3.5 kg/m 2 ; mean apnea-hypopnea index [AHI] 20.7, SD 17.8/hour). Among the 8 participants who completed the 4-week program, the overall compliance rate was 91% (175/192 sessions). For the tongue exercise, the success rate increased from 66% (211/320 exercises; SD 18%) on the first day to 85% (272/320 exercises; SD 17%) on the last day (P=.05). AHI did not change significantly after completion of training but a noteworthy correlation between successful lip exercise improvement and AHI reduction in the supine position was observed (R s =-0.76; P=.03). These findings demonstrate the potential of the device for accurately monitoring participants' performance in lip and tongue pressure exercises during myofunctional therapy. The diversity of the training program (it mixed exercises mixed training games), its ability to provide direct feedback for each exercise to the participants, and the easy measurement of treatment adherence are major strengths of our training program., Conclusions: The study's portable device for home-based myofunctional therapy shows promise as a noninvasive alternative for reducing the severity of OSAHS, with a notable correlation between successful lip exercise improvement and AHI reduction, warranting further development and investigation., (©Patrice Roberge, Jean Ruel, André Bégin-Drolet, Jean Lemay, Simon Gakwaya, Jean-François Masse, Frédéric Sériès. Originally published in JMIR Biomedical Engineering (http://biomsedeng.jmir.org), 15.04.2024.)

Sarcopenia involves a progressive loss of skeletal muscle force, quality and mass during ageing, which results in increased inability and death; however, no cure has been established thus far. Growth differentiation factor 5 (GDF5) has been described to modulate muscle mass maintenance in various contexts. For our proof of concept, we overexpressed GDF5 by AAV vector injection in Tibialis Anterior (TA) muscle of adult aged (20 months) mice and performed molecular and functional analysis of skeletal muscle. We analysed human Vastus Lateralis muscle biopsies from adult young (21-42 years) and aged (77-80 years) donors, quantifying the molecular markers modified by GDF5 overexpression (OE) in mouse muscle. We validated the major effects of GDF5 overexpression using human immortalized myotubes and Schwann Cells (SCs). We established a pre-clinical study by treating chronically (for 4 months) aged mice using recombinant GDF5 protein (rGDF5) in systemic administration and evaluated the long-term effect of this treatment on muscle mass and function. Here, we demonstrated that GDF5 OE in the old TAs promoted an increase of 16.5% of muscle weight (P = 0.0471) associated with a higher percentage of 5000-6000 µm2 large fibres (P = 0.0211), without the induction of muscle regeneration. Muscle mass gain was associated with an amelioration of 26.8% of rate of force generation (P = 0.0330) and a better neuromuscular connectivity (P = 0.0098). Moreover, GDF5 OE preserved neuromuscular junction (NMJ) morphology (38.5% of nerve terminal area increase, P < 0.0001) and stimulated the expression of re-innervation-related genes, in particular markers of SCs (fold change 3.19 for S100b gene expression, P = 0.0101). To further characterize the molecular events induced by GDF5 OE during ageing, we performed a genome-wide transcriptomic analysis of treated muscles and showed that this factor leads to a "rejuvenating" transcriptomic signature in aged mice, as 42% of the transcripts dysregulated by ageing reverted to youthful expression levels upon GDF5 OE (P < 0.05). Towards a pre-clinical approach, we performed a long-term systemic treatment using rGDF5 and showed its effectiveness in counteracting age-related muscle wasting, improving muscle function (17,8% of absolute maximal force increase, P = 0.0079), ensuring neuromuscular connectivity and preventing NMJ degeneration (7,96% of AchR area increase, P = 0.0125). In addition, in human muscle biopsies, we found the same age-related alterations than those observed in mice and improved by GDF5 and reproduced its major effects on human cells, suggesting this treatment as efficient in humans. Overall, these data provide a foundation to examine the curative potential of GDF5 drug in clinical trials for sarcopenia and, eventually, other neuromuscular diseases., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

The aim of the study was to establish the relationship between the content of Cd and Cu in the air, drinking water, musculature of fish (Cyprinus carpio L.) and the blood serum of patients with and without COPD. The amount of PM10 has highest values in 2017 (average annual value 25.2 µg/m3). The results regarding the amounts of cadmium in the air of the Stara Zagora region clearly show the absence of pollution. Determination of the amounts of the studied heavy metals in drinking water and the blood serum of the patients was carried out by the method of atomic absorption. The values of Cu, registered during the year-long study into the water of Stara Zagora and Radnevo are much lower than those adopted in Bulgarian legislation norms of 2 mg/l. The highest value of Cd is characterized by the drinking water in Stara Zagora Town from January 2020 (0.0047 mg/l), the value of which almost reaches the norm of 0.005 mg/l, defined in the normative documents. The cadmium concentrations measured during the same period in the drinking water of the Radnevo City are significantly below the accepted norms. Concentrations of copper in musculature of common carp of from our study from 2015 were significantly lower than the norms in force at that time (Regulation 31 of 2004, laying down maximum levels for certain contaminants in foods). Ovcharitsa Dam (0.60 mg/kg) is characterized by the highest values, far below the norms regulated in the then current Regulation 31 (10 mg/kg). Minimum concentration was measured in the muscles of carp inhabiting the Pastren Dam (0.27 mg/kg). Against the background of extremely low values of the element cadmium in the muscles of the studied specimens of the species Cyprinus carpio L. the highest is the concentration measured in the samples from Opan Dam (0.0110 mg/kg), and the lowest in the samples from Pastren Dam (0.006 mg/kg). These concentrations are much lower than the MAC specified in the then active Regulation 31, as well as in the current Regulation 15 and Regulation 1881 (EU). [ABSTRACT FROM AUTHOR]

The aim of the study was to establish the relationship between the content of Pb and Zn in the air, water, musculature of fish (Cyprinus carpio L.) and the blood serum of patients with and without COPD. The determination of the amounts of the studied heavy metals in drinking water and the blood serum of the patients was carried out by the method of atomic absorption. The concentrations of Pb in the air do not exceed the requirements of Regulation 12 of 15.07.2010. The levels of lead found in the drinking water of the of Stara Zagora Town in the period June 2019 - July 2020 often approach the limit value determined by Regulation 9 of 16.03.2001 (0.01 mg/l). The established concentrations of zinc in the drinking water of the cities of Radnevo and Stara Zagora during the reported period are lower than the MAC of 4 mg/l defined in the normative documents. The analysis of the data on our study of 2015 for the content of Zn in the musculature of common carp does not show an excess of the MAC set by the then current Regulation 31. The highest levels of zinc, which do not even approach the established norms were reached in muscle samples from fish delivered from Ovcharitsa Dam (8.09 mg/kg). With the lowest measured concentrations characterized Pastren Dam (2.69 mg/kg). Musculature samples from all studied water bodies do not exceed the MAC for lead, indicated in the then valid Regulation 31 and now the current Regulation 5 of the Bulgarian legislation and EC Regulation 1881 of 2006 with amendment from 2010 for determining the maximum permissible concentrations of some contaminants in foods. Although the values obtained are much lower than the regulated MAC, the highest concentrations are characterized carps from Lake Pastren Dam (0.04 mg/kg), and the lowest those from the Ovcharitsa Dam (0.01 mg/kg). [ABSTRACT FROM AUTHOR]

The cephalic anatomical structures of Morinoia japonica were examined using X-ray micro-computed tomography (micro-CT), 3D reconstruction and scanning electron microscopy (SEM), to improve understanding of terrestrial adaptation and phylogenetic inferences. The cerebral nerves, skeletons and musculatures were described in detail based on the observation results. As observed with other terrestrial amphipoids, M. japonica has a reduction in size of the olfactory lobes in the small deutocerebrum and the antenna 1 nerve (in short antennae 1), which might be the apomorphies of Talitridae. Organ of Bellonci is absent in M. japonica. The unfused tentorial arms of M. japonica might be a plesiomorphic state in Amphipoda. The fusion of both peduncular articles 1 and 2 of antenna 2 is another apomorphy of Talitridae, which is also the taxonomic diagnosis of the family. The cephalic musculatures of M. japonica , another amphipod species Gammarus minus (Gammaridae), Daphnia (Branchiopoda), Godzilliognomus frondosus (Remipedia) and Dicondylia (Insecta) were homologized. The markedly reduced foregut muscles of M. japonica are suggested to be associated with its feeding on soft moss. [ABSTRACT FROM AUTHOR]

Background: Monogeneans, in general, show a range of unique adaptations to a parasitic lifestyle, making this group enormously diverse. Due to their unique biological properties, diplozoid monogeneans represent an attractive model group for various investigations on diverse biological interactions. However, despite numerous studies, there are still gaps in our knowledge of diplozoid biology and morphofunctional adaptations. Results: In this study, we provide a comprehensive microscopic analysis of systems/structures involved in niche searching, sensing and self-protection against the host environment, and excretory/secretory processes in Eudiplozoon nipponicum. Freeze-etching enabled us to detect syncytium organisational features not visible by TEM alone, such as the presence of a membrane subjacent to the apical plasma membrane (separated by a dense protein layer) and a lack of basal plasma membrane. We located several types of secretory/excretory vesicles and bodies, including those attached to the superficial membranes of the tegument. Giant unicellular glands were seen accumulating predominantly in the apical forebody and hindbody haptor region. Muscle layer organisation differed from that generally described, with the outer circular and inner longitudinal muscles being basket-like interwoven by diagonal muscles with additional perpendicular muscles anchored to the tegument. Abundant muscles within the tegumentary ridges were detected, which presumably assist in fixing the parasite between the gill lamellae. Freeze-etching, alongside transmission electron and confocal microscopy with tubulin labelling, enabled visualisation of the protonephridia and nervous system, including the peripheral network and receptor innervation. Three types of receptor were identified: 1) uniciliated sensory endings with a subtle (or missing) tegumentary rim, 2) obviously raised uniciliated receptors with a prominent tegumentary rim (packed with massive innervation and muscles) and 3) non-ciliated papillae (restricted to the hindbody lateral region). Conclusions: This study points to specific morphofunctional adaptations that have evolved in diplozoid monogeneans to confront their fish host. We clearly demonstrate that the combination of different microscopic techniques is beneficial and can reveal hidden differences, even in much-studied model organisms such as E. nipponicum. [ABSTRACT FROM AUTHOR]

In aquacultures, heavy metals could be accumulated in fish tissues from natural and human-related sources depending on different factors. This study aims to estimate the level of bioaccumulation of heavy metals in cultured Gilt-head sea bream Sparusaurata. In this regard, heavy metals concentrations were measured in both water and fish musculature that were collected from a private fish farm in Kafr ElSheikh, Egypt. Regarding the water samples, heavy metals were within the permissible limits with exception of Cd, Cu, and Zn. In fish musculature, all heavy metals were within the WHO/FAO permissible limits. The bioaccumulation factor (BAF) indicated that mostly all heavy metals accumulation in the Gilt-head sea bream musculature decreased with time which may be correlated with the increase in water pH, calcium, and other cations concentrations. The hazard index (HI) calculations indicate no adverse health effects of heavy metals on humans through daily fish consumption so far. However, health risks are not negligible making the regular monitoring of metal contaminants in the studied area a necessity. [ABSTRACT FROM AUTHOR]

Ninety wild Atlantic salmon, Salmo salar L., (1.5–10.3 kg) were caught in the Namsen Fjord near the mouth of River Namsen, mid‐Norway, and examined for the presence and distribution of Anisakis simplex (Rudolphi, 1809 det. Krabbe, 1878) larvae by digestion of the viscera and muscles in a pepsin/HCl solution. All salmon were migrating spawners after 1–4 years of feeding in the Atlantic Ocean. All 90 Atlantic salmon had A. simplex larvae in the viscera, and all, except two, had A. simplex larvae in the musculature. The number of A. simplex larvae in each fish varied between 3 and 181, and the total mean number of nematode larvae was 44.5. The intensity of A. simplex larvae was positively correlated with increasing weight and sea age of the host. However, the proportion of larvae in the muscle fillets decreased with increasing host weight and sea age. Atlantic salmon females had more A. simplex larvae than males. In all the fish examined, 70.2% of the A. simplex larvae were found in the viscera and 29.8% in the musculature. The majority (93%) of the larvae in the musculature occurred in the hypaxial sections anterior to the anus. As A. simplex larvae commonly occur in the musculature of wild Atlantic salmon, consumption of unfrozen, raw or semi‐raw musculature represents a risk for humans developing anisakiasis. [ABSTRACT FROM AUTHOR]

Animal body parts evolve with variable degrees of integration that nonetheless yield functional adult phenotypes: but, how? The analysis of modularity with Anatomical Network Analysis (AnNA) is used to quantitatively determine phenotypic modules based on the physical connection among anatomical elements, an approach that is valuable to understand developmental and evolutionary constraints. We created anatomical network models of the head, forelimb, and hindlimb of two taxa considered to represent a 'generalized' eutherian (placental: mouse) and metatherian (marsupial: opossum) anatomical configuration and compared them with our species, which has a derived eutherian configuration. In these models, nodes represent anatomical units and links represent their physical connection. Here, we aimed to identify: (1) the commonalities and differences in modularity between species, (2) whether modules present a potential phylogenetic character, and (3) whether modules preferentially reflect either developmental or functional aspects of anatomy, or a mix of both. We predicted differences between networks of metatherian and eutherian mammals that would best be explained by functional constraints, versus by constraints of development and/or phylogeny. The topology of contacts between bones, muscles, and bones + muscles showed that, among all three species, skeletal networks were more similar than musculoskeletal networks. There was no clear indication that humans and mice are more alike when compared to the opossum overall, even though their musculoskeletal and skeletal networks of fore‐ and hindlimbs are slightly more similar. Differences were greatest among musculoskeletal networks of heads and next of forelimbs, which showed more variation than hindlimbs, supporting previous anatomical studies indicating that in general the configuration of the hindlimbs changes less across evolutionary history. Most observations regarding the anatomical networks seem to be best explained by function, but an exception is the adult opossum ear ossicles. These ear bones might form an independent module because the incus and malleus are involved in forming a functional primary jaw that enables the neonate to attach to the teat, where this newborn will complete its development. Additionally, the human data show a specialized digit 1 module (thumb/big toe) in both limb types, likely the result of functional and evolutionary pressures, as our ape ancestors had highly movable big toes and thumbs. [ABSTRACT FROM AUTHOR]

Previous studies on neck muscle strength and motion have assumed or imposed varying constraints on the heads and bodies of the subjects. In this study, we asked 20 subjects to vigorously shake their heads 5-10 times in a completely unconstrained manner. The kinematics and kinetics of the head and neck were measured from video analysis and instrumentation mounted inside the mouth. Subjects shook their heads at self-selected tempos ranging from 1.9-4.7 Hz over a 20-91° range of motion. The motion of each subject's head could be approximated by a fixed center of rotation that was typically located in the midcervical spine, but varied widely among subjects. Significant differences between men and women were observed. Peak head accelerations were low (4.3 ± 1.1 g and 250 ± 103 rad/s2 for men, 3.0 ± 0.9 g and 182 ± 58 rad/s2 for women) and estimated peak generated neck moments at C7/T1 were comparable to values reported in isometric neck strength studies (47 ± 14 N-m in extension and 22 ± 9 N·m in llexion for men, 25 ± 8 N·m in extension and 9 ± 7 N·m in flexion for women). [ABSTRACT FROM AUTHOR]

Aberrant kinorhynchs show several modifications deviating from the typical kinorhynch body plan, including a modified introvert with very elongated and flexible scalids, a weakly developed neck, and a slender trunk with less distinct segmentation. How these aberrant external features are reflected in the inner anatomy and how their aberrant body plan evolved are not understood. Here, we provide a comprehensive and comparative myoanatomical study of three putatively, distantly related worm-like species: Cateria styx, Franciscideres kalenesos and Zelinkaderes yong. Despite the weak external segmentation of the trunk, the studied species show a distinct segmental arrangement of the musculature. However, this arrangement is shifted posteriorly with respect to the external segmentation, because the extremely thin and flexible cuticle is lacking the apodeme-like cuticular thickenings (pachycycli) where the longitudinal muscles usually attach. The muscular arrangement in the three species is overall similar, yet, C. styx shows most resemblance to the allomalorhagid F. kalenesos, whereas the cyclorhagid Z. yong differs in several ways. This suggests a closer relationship of C. styx to Allomalorhagida. Whereas most kinorhynchs prefer muddy sediments, both the allomalorhagid and cyclorhagid worm-like kinorhynchs are mainly found in sandy environments, suggesting that a flexible, slender body evolved at least twice independently as an adaptation to the interstitial environment. [ABSTRACT FROM AUTHOR]

Although most millipedes (Diplopoda) show a biting–chewing feeding mode, representatives of the so‐called Colobognatha (Platydesmida, Polyzoniida, Siphonocryptida, Siphonophorida), with their more or less reduced mouthparts, are assumed to have evolved a suctorial feeding mode, which enables them to exploit food sources like algal film and fungi hyphae. The Platydesmida are viewed as the key taxon for the understanding of mouthpart adaptations in Colobognatha, as their mouthpart elements still closely resemble those of biting–chewing millipedes. Studies of the skeletomuscular system of the Platydesmida are rare, impeding further understanding of the mouthpart evolution in millipedes. To overcome this impediment in the understanding of millipede evolution, we study the internal morphology of the head in specimens from four genera of Platydesmida: Brachycybe lecontii, Dolistenus spp., Gosodesmus claremontus, and Pseudodesmus spp. Although all Platydesmida show similarly structured skeletal elements and accompanying musculature, they are distinct from all other Diplopoda. Their head lacks eyes and organs of Tömösváry, and is pyriform and posteriorly bulging, overlapping the collum. The narrow mandibles are hidden underneath the broad genae. A previously described gnathochilarial postmentum is absent. Muscle attachment sites, such as the transverse mandibular tendon and the median septum, are reduced. The strong modifications of the head capsule, mandibles, and musculature limit the movability of the mandible for biting–chewing motions based on simulations of possible gape angles. Platydesmida likely show a scraping and slurping feeding mode, which is facilitated by the comparably well‐developed pharyngeal dilator muscles. We suggest that the Platydesmida show an intermediate state between the biting–chewing millipedes and the other suctorially feeding Colobognatha. [ABSTRACT FROM AUTHOR]

The present work focuses on the study of localization of peptidergic neurons and muscle fibers of body wall musculature in planarians Girardia tigrina and Polycelis tenuis with the use of immunohistochemistry, immunocytochemistry, fluorescent microscopy, and confocal laser scanning microscopy. A close spatial relationship between FMRFamide-immunopositive nerve fibers and myofilaments is shown. Such localization of peripheral peptidergic nerve fibers may suggest an important role FMRF-like neuropeptides play in the regulation of muscle function. Physiological analysis of the muscle cells isolated from the planarian Procerodes littoralis confirmed that native flatworm FMRF-like peptides GYIRF and YIRF have the inducing effect on muscle contractions in planarians. It was found that dihydropyridine calcium channel blockers (nicardipine, nitrendipine, and nifedipine), as well as ryanodine, an antagonist of the endoplasmic reticulum calcium channels, inhibited peptide-induced muscle contraction. The blockers of the intracellular calcium ions reuptake (thapsigargin and cyclopiazonic acid) decreased the number of peptide-induced muscular responses. The findings suggest that FMRF-like peptide-induced muscle contraction is dependent on calcium ions from both extracellular pool and intracellular stores. The results demonstrate the presence of different receptors and ion channels controlling muscle contractions in flatworms. [ABSTRACT FROM AUTHOR]

A particularly conspicuous morphological feature in chalcidoid wasps are strikingly modified legs present in both males and females. It evolved convergently multiple times on either fore or hind legs implying strong evolutionary pressure and a prominent function in the wasps' life history. We investigate the external and internal morphology of the modified legs of five species of chalcidoid wasps representing four families (Ooderidae, Heydeniidae, Chalcididae, and Leucospidae), using light microscopy, scanning electron microscopy and micro computed tomography. We aimed to identify shared characteristics as well as differences between genera/species, leg pairs and sexes and to draw first conclusions about the shared or different functions. All species and sexes share the same general leg morphology, with enlarged femur, curved tibia and a huge flexor tibiae muscle. However, there are also genus/species-specific differences such as distinctive spine-like setae on the femur of Oodera spp., or leg pair-specific differences in the position of the extensor tibiae muscle. Shared characteristics imply a common primary function in which strong forces are required to pull the tibia against the femur while differences imply different secondary functions. Both primary and secondary functions have yet to be revealed beyond informed speculations. [Display omitted] • Convergently evolved modified legs in chalcidoid wasps harbour enlarged musculature. • 3D visualisation of modified legs in Chalcidoidea. • All legs have enlarged femur, curved tibia, small joints and a huge flexor tibiae. • Common primary function of grasping, different still unknown secondary functions. [ABSTRACT FROM AUTHOR]

The present study aims to determine the levels of the heavy metals manganese (Mn) and zinc (Zn) contained in the fungicide Mancozeb in the eggs and musculature of the rainbow trout (Oncorhynchus mykiss W.) which have grown in an environment, containing a permissible amount of Mancozeb and fed with or without the carotenoid pigment astaxanthin. The study follows the feeding, then the analysis of the level of Mn and Zn in the eggs and musculature of the rainbow trout, treated with and without the pigment astaxanthin and the fungicide Mancozeb. The determination of Mn and Zn concentrations is performed using a modern method for measuring macro- and microelements with an atomic absorption spectrometer, which is characterized by high selectivity, swiftness and sensitivity. Experimental data show accumulation of Mn and Zn, contained in the fungicide Mancozeb even when its concentration in the habitat does not exceed the maximum permissible levels in the normative documents. As a result, the analysis of the eggs and musculature shows the same trend regarding the accumulation of Mn and Zn. In non-fertilized, as well as in fertilized rainbow trout eggs and musculature, the experimental data show a slight increase of Mn and Zn in the presence of only astaxanthin in the added feed and a significant decrease in these metals in the presence of both astaxanthin and Mancozeb. The supplementation of astaxanthin in the diet can significantly reduce the rate of heavy metals accumulation in fish tissues and eggs, but high concentrations of these pollutants in the aquatic environment over a longer period of time would certainly result in metabolic disturbances in the fish body and reduction of their eggs’ hatchability.

Abstract Background The facial musculature is a remarkable anatomical complex involved in vital activities of fishes, such as food capture and gill ventilation. The evolution of the facial muscles is largely unknown in most major fish lineages, such as the Actinopterygii. This megadiverse group includes all ray-finned fishes and comprises approximately half of the living vertebrate species. The Polypteriformes, Acipenseriformes, Lepisosteiformes, Amiiformes, Elopiformes, and Hiodontiformes occupy basal positions in the actinopterygian phylogeny and a comparative study of their facial musculature is crucial for understanding the cranial evolution of bony fishes (Osteichthyes) as a whole. Results The facial musculature of basal actinopterygians is revised, redescribed, and analyzed under an evolutionary perspective. We identified twenty main muscle components ontogenetically and evolutionarily derived from three primordial muscles. Homologies of these components are clarified and serve as basis for the proposition of a standardized and unifying myological terminology for all ray-finned fishes. The evolutionary changes in the facial musculature are optimized on the osteichthyan tree and several new synapomorphies are identified for its largest clades, including the Actinopterygii, Neopterygii, and Teleostei. Myological data alone ambiguously support the monophyly of the Holostei. A newly identified specialization constitutes the first unequivocal morphological synapomorphy for the Elopiformes. The myological survey additionally allowed a reinterpretation of the homologies of ossifications in the upper jaw of acipenseriforms. Conclusions The facial musculature proved to be extremely informative for the higher-level phylogeny of bony fishes. These muscles have undergone remarkable changes during the early radiation of ray-finned fishes, with significant implications for the knowledge of the musculoskeletal evolution of both derived actinopterygians and lobe-finned fishes (Sarcopterygii).

We investigated and described the thoracic structures, jumping mechanism, and promesothoracic interlocking mechanism of the click beetle Campsosternus auratus (Drury) (Elateridae: Dendrometrinae). Two experiments were conducted to reveal the critical muscles and sclerites involved in the jumping mechanism. They showed that M2 and M4 are essential clicking-related muscles. The prosternal process, the prosternal rest of the mesoventrite, the mesoventral cavity, the base of the elytra, and the posterodorsal evagination of the pronotum are critical clicking-related sclerites. The destruction of any of these muscles and sclerites resulted in the loss of normal clicking and jumping ability. The mesonotum was identified as a highly specialized saddle-shaped biological spring that can store elastic energy and release it abruptly. During the jumping process of C. auratus, M2 contracts to establish and latch the clicking system, and M4 contracts to generate energy. The specialized thoracic biological springs (e.g., the prosternum and mesonotum) and elastic cuticles store and abruptly release the colossal energy, which explosively raises the beetle body in a few milliseconds. The specialized trigger muscle for the release of the clicking was not found; our study supports the theory that the triggering of the clicking is due to the building-up of tension (i.e., elastic energy) in the system.

The musculature is one of the best studied organ systems in brachiopods, being approachable not only by dissecting recent species of brachiopods, but also by exploring muscle scars in fossil material. In the present study, the muscular anatomy of Novocrania anomala is studied using 3D reconstructions based on microcomputed tomography. Muscles of N. anomala may be subdivided into two groups: those related to movements of the lophophore, and those connected to movements of shell valves. Muscles, their morphology and possible functions, such as brachial protractors, elevators, and retractors, as well as anterior adductors, are described and discussed. We also provide the discussion of craniid muscle terminology, consider the valve-opening mechanism. The investigation of muscle scars on dorsal valves supports the conclusion that the shape of muscle scars should be used for description and distinction of recent and extinct species only when visible distinctness cannot be explained by substrate differences. This study, which is aimed at improving our understanding the anatomy and functioning of muscles in craniids, will be useful not only for zoologists, but also for paleontologists., (© 2024 Wiley Periodicals LLC.)

The jaw apparatus in several annelid families represents a powerful tool for systematic approaches and evolutionary investigations. Nevertheless, for several taxa, this character complex has scarcely been investigated, and complete comparative analyses of all annelid jaws are lacking. In our comprehensive study, we described the fine structure of the jaw apparatus and the ventral pharyngeal organ (VPO) in Histriobdella homari – a minute ectocommensal of lobsters putatively belonging to the Eunicida – using different comparative morphological approaches, including SEM, TEM, CLSM and subsequent 3D reconstruction. The H. homari jaw apparatus is composed of ventral paired mandibles and dorsal symmetrical maxillae consisting of numerous dental plates, ventral carriers and an unpaired dorsal rod, and the general assemblage and arrangement of the different parts are highly comparable to those of other eunicid families. The jaw ultrastructure of histriobdellids resembles that of the families Dorvilleidae and (juvenile) Onuphidae. Furthermore, our data reveal that in the process of development of the jaw apparatus, the mandibles, maxillae II and unpaired dorsal rod are formed first, and the remaining maxillae and ventral carriers appear later. Notably, the muscular apparatus differs from that in Dorvilleidae and Onuphidae in terms of the number and arrangement of muscle fibers encompassing the jaws – not only because of the very small size of Histriobdella but also because histriobdellid maxillary protraction occurs due to straightening of the dorsal rod and thus requires a different muscular scaffold. Based on our investigations, the arrangement of the muscular apparatus of the jaws, the presence of paired ventral carriers and the dorsal rod, and the morphology of the ventral pharyngeal organ represent a histriobdellid autapomorphy. Our datasets form a basis for further comparative analyses to elucidate the evolution of Eunicida and jaw-bearing Annelida. [ABSTRACT FROM AUTHOR]

Parasitic wasps use specialized needle‐like structures, ovipositors, to drill into substrates to reach hidden hosts. The external ovipositor (terebra) consists of three interconnected, sliding elements (valvulae), which are moved reciprocally during insertion. This presumably reduces the required pushing force on the terebra and limits the risk of damage whilst probing. Although this is an important mechanism, it is still not completely understood how the actuation of the valvulae is achieved, and it has only been studied with the ovipositor in rest position. Additionally, very little is known about the magnitude of the forces generated during probing. We used synchrotron X‐ray microtomography to reconstruct the actuation mechanism of the parasitic wasp Diachasmimorpha longicaudata (Braconidae) in four distinct phases of the probing cycle. We show that only the paired first valvulae of the terebra move independently, while the second valvula moves with the metasoma ('abdomen'). The first valvula movements are initiated by rotation of one chitin plate (first valvifer) with respect to another such plate (second valvifer). This is achieved indirectly by muscles connecting the non‐rotating second valvifer and the abdominal ninth tergite. Contrary to previous reports, we found muscle fibres running inside the terebra, although their function remains unclear. The estimated maximal forces that can be exerted by the first valvulae are small (protraction 1.19 mN and retraction 0.874 mN), which reduces the risk of buckling, but are sufficient for successful probing. The small net forces of the valvulae on the substrate may still lead to buckling of the terebra; we show that the sheaths surrounding the valvulae prevent this by effectively increasing the diameter and second moment of area of the terebra. Our findings improve the comprehension of hymenopteran probing mechanisms, the function of the associated muscles, and the forces and damage‐limiting mechanism that are involved in drilling a slender terebra into a substrate. [ABSTRACT FROM AUTHOR]

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Facial nerve palsy is the common problem of facial muscles weakness and facial appearance, mainly resulting of temporary or permanent damage of any structures innervated by the facial nerve. It can be congenital or acquired. About 45 to 75% of unilateral facial nerve palsy cases are still idiopathic. Facial palsy impairment significantly affects swallowing, articulation, and lip sufficiency. Diminished facial expression can pose challenges in face-to-face communications that affects their psychological consequences which lead to negative impact on the quality of life. This article reviews on the assessment and management for the communication and quality of life. Speech-language therapy in facial paralysis aims in the rehabilitation of oral functions such as verbal and non-verbal communication, swallowing and vegetative skills. [ABSTRACT FROM AUTHOR]

Segmental, paired locomotory appendages are a characteristic feature of Panarthropoda—a diversified clade of moulting animals that includes onychophorans (velvet worms), tardigrades (water bears) and arthropods. While arthropods acquired a sclerotized exoskeleton and articulated limbs, onychophorans and tardigrades possess a soft body and unjointed limbs called lobopods, which they inherited from Cambrian lobopodians. To date, the origin and ancestral structure of the lobopods and their transformation into the jointed appendages are all poorly understood. We therefore combined high-resolution computed tomography with high-speed camera recordings to characterize the functional anatomy of a trunk lobopod from the onychophoran Euperipatoides rowelli. Three-dimensional reconstruction of the complete set of muscles and muscle fibres as well as non-muscular structures revealed the spatial relationship and relative volumes of the muscular, excretory, circulatory and nervous systems within the leg. Locomotory movements of individual lobopods of E. rowelli proved far more diverse than previously thought and might be governed by a complex interplay of 15 muscles, including one promotor, one remotor, one levator, one retractor, two depressors, two rotators, one flexor and two constrictors as well as muscles for stabilization and haemolymph control. We discuss the implications of our findings for understanding the evolution of locomotion in panarthropods.