Ventral Muscles Research Articles

Sutural variation in the ammonites Oxynoticeras and Cheltonia from the Lower Jurassic of Bishop's Cleeve, Gloucestershire, England and its significance for ammonite growth

Large samples of pyritized ammonites of Oxynoticeras and Cheltonia from the Lower Jurassic of Bishop's Cleeve, Gloucestershire, England, reveal that a majority retain parts of the body chamber and died as juveniles. Both genera exhibit similar high variation in sutural angle, chamber size and numbers of chambers per whorl, suggesting they are closely related, perhaps sexual dimorphs. Many examples preserve impressions of paired dorsal and unpaired ventral muscle scars, as well as drag bands and (more rarely) pseudosutures. All stages of the chamber formation cycle described in Recent Nautilus can be recognised in both genera. Juvenile ammonites apparently died at random times in the chamber formation cycle. Frequency of incomplete final septa suggests that septal secretion took about 30% of the full cycle. Rare examples from a restricted horizon preserve narrow, radiating darker bands on the internal moulds. Mean chamber angle and mean angle between dark bands correlate strongly in Cheltonia, suggesting formation of dark bands was related to septal secretion. The dark bands are interpreted as false colour bands secreted on the inside of the aperture during pauses in growth, but there is no other evidence for episodic growth in either genus. Spacing of growth lines is similar to that reported for Recent Nautilus and to spacing of pseudosutures. Both genera may have moved their bodies forward slowly during chamber formation, unlike the rapid movement in Nautilus. This may be one way in which ammonite growth differed from that of Nautilus. Irregular chamber sizes in both ammonites suggest that the period of chamber formation varied, perhaps due to variable pauses in apertural growth. At least Oxynoticeras and Cheltonia grew much more irregularly than modern Nautilus.

Biological Investigation of Wing Motion of the Manduca Sexta

An investigation was conducted assessing the feasibility of reproducing the biological flapping motion of the wings of the hawkmoth, Manduca sexta (M.sexta) by artificially stimulating the flight muscles for Micro Air Vehicle research. Electromyographical signals were collected using bipolar intramuscular fine wire electrodes inserted into the primary flight muscles, the dorsal longitudinal and dorsal ventral muscles, of the adult M.sexta. These signals were recorded and associated with wing movement using high speed video. The signals were reapplied into the corresponding muscle groups with the intention of reproducing similar flapping motion. A series of impulse signals were also directed into the primary flight muscles as a means of observing muscle response through measured forewing angles. This study pioneered electromyographic research on M.sexta at the Air Force Institute of Technology with tests conducted with fine wire electrodes. Through this process, the research showed the deformational structural changes that take place when a wing is removed from an insect and proved that muscular stimulation is a viable method for generating wing movement. This study also assisted in developing an understanding related to the role that a thorax-like fuselage could play in future micro aircraft designs. This study has shown that partial neuromuscular control of the primary flight muscles of M.sexta is possible with electrical stimulants which could be used to directly control insect flight.

Effects of Brief Summer or Winter Fasting on the Muscle Quality of Cultured Pacific Bluefin Tuna (Thunnus orientalis)

The effects of fasting on the quality of the dorsal and ventral ordinary muscles from cultured Pacific bluefin tuna (Thunnus orientalis) during chilled storage were investigated. Tuna were subjected to fasting for 2 days in the summer or 6 days in the winter prior to harvesting. The breaking strength of the dorsal ordinary muscle sampled in the summer increased until 24 h and then decreased. There were no significant differences in the lipid and glycogen content of the ordinary muscle after 9 h of storage between the controls and either fasting group. The pH of the ordinary muscle subjected to summer and winter fasting was higher than in the controls after 24–48 h of storage. However, the relationship between the pH and glycogen content was unclear. The metmyoglobin content during chilled storage was lower in the ordinary muscles from either fasting group than in the controls. In conclusion, fasting for 6 days in the winter improved the color stability of the ordinary muscle without a decline in its lipid content.

The hyal and ventral branchial muscles in caecilian and salamander larvae: Homologies and evolution

Amphibians (Lissamphibia) are characterized by a bi-phasic life-cycle that comprises an aquatic larval stage and metamorphosis to the adult. The ancestral aquatic feeding behavior of amphibian larvae is suction feeding. The negative pressure that is needed for ingestion of prey is created by depression of the hyobranchial apparatus as a result of hyobranchial muscle action. Understanding the homologies of hyobranchial muscles in amphibian larvae is a crucial step in understanding the evolution of this important character complex. However, the literature mostly focuses on the adult musculature and terms used for hyal and ventral branchial muscles in different amphibians often do not reflect homologies across lissamphibian orders. Here we describe the hyal and ventral branchial musculature in larvae of caecilians (Gymnophiona) and salamanders (Caudata), including juveniles of two permanently aquatic salamander species. Based on previous alternative terminology schemes, we propose a terminology for the hyal and ventral branchial muscles that reflects the homologies of muscles and that is suited for studies on hyobranchial muscle evolution in amphibians. We present a discussion of the hyal and ventral branchial muscles in larvae of the most recent common ancestor of amphibians (i.e. the ground plan of Lissamphibia). Based on our terminology, the hyal and ventral branchial musculature of caecilians and salamanders comprises the following muscles: m. depressor mandibulae, m. depressor mandibulae posterior, m. hyomandibularis, m. branchiohyoideus externus, m. interhyoideus, m. interhyoideus posterior, m. subarcualis rectus I, m. subarcualis obliquus II, m. subarcualis obliquus III, m. subarcualis rectus II-IV, and m. transversus ventralis IV. Except for the m. branchiohyoideus externus, all muscles considered herein can be assigned to the ground plan of the Lissamphibia with certainty. The m. branchiohyoideus externus is either apomorphic for the Batrachia (frogs + salamanders) or salamander larvae depending on whether or not a homologous muscle is present in frog tadpoles.

Functional anatomy of the cheetah (Acinonyx jubatus) forelimb

Despite the cheetah being the fastest living land mammal, we know remarkably little about how it attains such high top speeds (29 m s(-1)). Here we aim to describe and quantify the musculoskeletal anatomy of the cheetah forelimb and compare it to the racing greyhound, an animal of similar mass, but which can only attain a top speed of 17 m s(-1). Measurements were made of muscle mass, fascicle length and moment arms, enabling calculations of muscle volume, physiological cross-sectional area (PCSA), and estimates of joint torques and rotational velocities. Bone lengths, masses and mid-shaft cross-sectional areas were also measured. Several species differences were observed and have been discussed, such as the long fibred serratus ventralis muscle in the cheetah, which we theorise may translate the scapula along the rib cage (as has been observed in domestic cats), thereby increasing the cheetah's effective limb length. The cheetah's proximal limb contained many large PCSA muscles with long moment arms, suggesting that this limb is resisting large ground reaction force joint torques and therefore is not functioning as a simple strut. Its structure may also reflect a need for control and stabilisation during the high-speed manoeuvring in hunting. The large digital flexors and extensors observed in the cheetah forelimb may be used to dig the digits into the ground, aiding with traction when galloping and manoeuvring.

Evidence of a central pattern generator regulating spermathecal muscle activity inLocusta migratoriaand its coordination with oviposition

Electrophysiological recordings were conducted to determine the control of spermathecal contractions during oviposition of interrupted egg-laying locusts, Locusta migratoria. Following transection of the central nervous system below the metathoracic ganglion, rhythmic patterned bursting was detected by extracellular recordings of the nerve N2B2 that innervates the muscles of the spermatheca. Subsequent transections at more posterior regions of the ventral nerve cord revealed more robust rhythmic bursting in N2B2. This rhythmic bursting pattern was found to be coordinated with bursting in the ventral opener nerve (N2B1) that innervates the ventral opener muscle. This muscle controls the ventral ovipositor valves. Electromyographic recordings from the spermathecal muscle and ventral opener muscle confirmed a rhythmic bursting pattern resulting in an increase in muscle activity. Taken together, the results indicate that there is probably a central pattern generator (CPG), which is regulated by descending inhibition, that controls the spermathecal muscle activity. This CPG appears to be located within the VIIth and VIIIth abdominal ganglia, and was found to integrate with the CPG that regulates oviposition digging in locusts. These results provide further insight into the intricate coordination and control of reproductive tissues underlying reproductive behaviours in locusts.

Homologies of the branchial arch muscles in Zacco platypus (Teleostei: Cypriniformes: Cyprinidae): Evidence from innervation pattern

Homologies of the branchial arch muscles in the cyprinid Zacco platypus are assessed based on their innervation. Muscles serving the first gill arch are innervated by branches of the glossopharyngeal (IX) nerve and those serving other arches by the vagal (X) nerve. Absence of the levator posterior is confirmed. Five pairs of muscles originating from the cranium and inserted onto the specialized 5th ceratobranchial, all unique to cyprinids, are innervated by the 4th branchial trunks of X, indicating that all pairs are derivatives of the sphincter oesophagi, involving reorganization from intrinsic to extrinsic elements. Homologies of some ventral branchial muscles are also discussed and the criteria for homology improved by clarifying the innervation pattern.

Intertissue Mechanical Stress Affects Frizzled-Mediated Planar Cell Polarity in the Drosophila Notum Epidermis

Frizzled/planar cell polarity (Fz/PCP) signaling controls the orientation of sensory bristles and cellular hairs (trichomes) along the anteroposterior axis of the Drosophila thorax (notum). A subset of the trichome-producing notum cells differentiate as "tendon cells," serving as attachment sites for the indirect flight muscles (IFMs) to the exoskeleton. Through the analysis of chascon (chas), a gene identified by its ability to disrupt Fz/PCP signaling under overexpression conditions, and jitterbug (jbug)/filamin, we show that maintenance of anteroposterior planar polarization requires the notum epithelia to balance mechanical stress generated by the attachment of the IFMs. chas is expressed in notum tendon cells, and its loss of function disturbs cellular orientation at and near the regions where IFMs attach to the epidermis. This effect is independent of the Fz/PCP and fat/dachsous systems. The chas phenotype arises during normal shortening of the IFMs and is suppressed by genetic ablation of the IFMs. chas acts through jbug/filamin and cooperates with MyosinII to modulate the mechanoresponse of notum tendon cells. These observations support the notion that the ability of epithelia to respond to mechanical stress generated by one or more interactions with other tissues during development and organogenesis influences the maintenance of its shape and PCP features.

A single immunoglobulin-domain protein required for clustering acetylcholine receptors inC. elegans

At Caenorhabditis elegans neuromuscular junctions (NMJs), synaptic clustering of the levamisole-sensitive acetylcholine receptors (L-AChRs) relies on an extracellular scaffold assembled in the synaptic cleft. It involves the secreted protein LEV-9 and the ectodomain of the transmembrane protein LEV-10, which are both expressed by muscle cells. L-AChRs, LEV-9 and LEV-10 are part of a physical complex, which localizes at NMJs, yet none of its components localizes independently at synapses. In a screen for mutants partially resistant to the cholinergic agonist levamisole, we identified oig-4, which encodes a small protein containing a single immunoglobulin domain. The OIG-4 protein is secreted by muscle cells and physically interacts with the L-AChR/LEV-9/LEV-10 complex. Removal of OIG-4 destabilizes the complex and causes a loss of L-AChR clusters at the synapse. Interestingly, OIG-4 partially localizes at NMJs independently of LEV-9 and LEV-10, thus providing a potential link between the L-AChR-associated scaffold and local synaptic cues. These results add a novel paradigm for the immunoglobulin super-family as OIG-4 is a secreted protein required for clustering ionotropic receptors independently of synapse formation.

Conditional mutation of fibroblast growth factor receptors 1 and 2 results in an omphalocele in mice associated with disruptions in ventral body wall muscle formation

Background/Purpose We observed that fibroblast growth factor receptors 1 and 2 ( Fgfr1, Fgfr2) are expressed during abdominal wall development in mice and hypothesized that conditional mutation of these genes would result in abdomial wall defects. Methods Section in situ hybridizations were performed for Fgfr1 and Fgfr2 on wild-type embryos at embryonic day (E) 11.5 and E13.5. Conditional mutation of Fgfr1and Fgfr2 was achieved with a tamoxifen inducible Cre at E8.5. Litters were harvested at E17.5, whole mount photographs were taken, and paraffin sections were generated and stained with hematoxylin and eosin. Results Fgfr1 was expressed in ectoderm, lateral plate mesoderm, and myoblasts, whereas Fgfr2 was expressed almost exclusively in the early dermis and ectoderm of the abdominal wall. Conditional mutation of both Fgfr2 alleles and one Fgfr1 allele resulted in omphalocele in 38.7% of mutants. Histologic examination in mutants demonstrated disruptions in dermal and muscle development. Conclusions Mutant embryos with omphalocele arising from mutation in Fgfr1 and Fgfr2 exhibit disruptions in the development of the secondary abdominal wall structures. These findings are consistent with a model of ventral abdominal wall development in which organization of the muscles and connective tissue (secondary abdominal wall structures) is influenced by positional information emanating from the primary abdominal wall.

Ultrasonographic and Magnetic Resonance Imaging Diagnosis of an Oropharyngeal Wood Penetrating Injury in a Dog

A 5 yr old female intact English setter with a 17 day history of a penetrating oropharyngeal wound was referred for cervical swelling and pain. Physical examination revealed swelling at the left lateral aspect of the cranial cervical region. Pain was elicited upon flexion, extension, and leftward movement of the neck. Neurologic deficits were not identified. Cervical ultrasonography showed a 0.4 cm × 2.3 cm linear, hyperechoic structure in the soft tissues ventrolateral to the first (C1) and second (C2) cervical vertebrae. MRI demonstrated a linear structure 2 cm in length adjacent to the cranial aspect of C2. The foreign material was isointense to hyperintense on precontrast T1-weighted images, isointense on postcontrast T1-weighted images, and hypointense on T2-weighted images relative to adjacent muscle. Abnormalities within the spinal canal were not identified. Upon surgical exploration, a reed foreign body was identified deep to the serratus ventralis muscle. The patient was normal on follow-up evaluations 4 wk postsurgically.

ANÁLISE HISTOLÓGICA, HISTOQUÍMICA E ULTRAESTRUTURAL DA MUSCULATURA DORSAL E VENTRAL DO GUARU (Poecilia vivipara BLOCHI & SCHNEIDER, 1801)

Poecilia vivipara (guaru), a neotropical, small, euryhaline fish, has been being used as a biomonitor. Dorsal and ventral muscles of Poecilia vivipara were analyzed to standardize methodologies for evaluating the normal tissue structure, in order to use them in toxicity studies. Thus, chemical and physical fixations were carried out, aiming at the histological and histochemical procedures of staining and reaction. The methods HE and MT revealed the organization of SSMF with epiaxial and hypaxial muscle bundles and associated conjunctive. MA marked the SSMF and facilitated the observation of sarcomeres in the presence of a thin metacromatically stained band. Part of the SSMF was positive PAS and reactive amylase, indicating the distribution of glycogen within the fibers. In the presence of SBB the fibers were reactive mainly in the dorsal region, indicating the presence of lipids. Cells with mitochondrial enzyme-rich cytoplasm were found in SDH pH 10.5. The SSMF stained with AT were arranged in alternating transverse bands, which correspond to the pattern seen under the MET. The use of these methodologies allowed the indication of Poecilia vivipara muscles as a tool for environmental variations studies, because its normal structure is standard in teleosts.KEYWORDS: Morphology, muscle fiber, neotropical fish.

Ultrastructure and molecular characterization of a microsporidium, Tubulinosema hippodamiae, from the convergent lady beetle, Hippodamia convergens Guérin-Méneville

Hippodamia convergens, the convergent lady beetle, is available for aphid control in home gardens and in commercial food production systems throughout the United States and Canada. Beetles received from commercial insectaries for biological control are occasionally infected with a microsporidium. The objective of this study was to describe the pathogen by means of ultrastructure, molecular characterization and tissue pathology. All stages of the microsporidium were in direct contact with the host cell cytoplasm. Early developmental stages were proximal to mature spores and both were observed throughout the tissue sections that were examined. Merogony resulted from binary fission. Early-stage sporoblasts were surrounded by a highly convoluted plasma membrane and contained an electron-dense cytoplasm and diplokaryon. Ovoid to elongated late-stage sporoblasts were surrounded by a relatively complete spore wall. The polar filament, polaroplast, and anchoring disk were readily observed within the cell cytoplasm. Mature spores were typical of terrestrial microsporidia, with a thickened endospore surrounded by a thin exospore. Spores contained well-defined internal structures, including a diplokaryon, lamellar polaroplast and a slightly anisofilar polar filament with 10–14 coils arranged in a single or double row. A prominent indentation was evident at the apical end of the spore wall proximal to the anchoring disk. Aberrant spores were also observed. These had a fully developed endospore and exospore but lacked any discernable internal spore structures, and were, instead, filled with lamellar or vesicular structures. Typical and aberrant spores measured 3.58 ± 0.2 × 2.06 ± 0.2 μm ( n = 10) and 3.38 ± 0.8 × 2.13 ± 0.2 μm ( n = 10), respectively. Spores were observed in longitudinal muscle surrounding the midgut and within the fat body, Malpighian tubules, pyloric valve epithelium, ventral nerve cord ganglia, muscles and ovaries. The hindgut epithelium was often infected but the connective tissues were rarely invaded. The life cycle and pathology of the microsporidium bears some resemblance to Nosema hippodamiae, the only microsporidium reported from H. convergens by Lipa and Steinhaus in 1959. Molecular characterization of the pathogen genomic DNA revealed that it is 99% similar to Tubulinosema acridophagus and T. ratisbonensis, two pathogens that infect Drosophila melanogaster and 98% similar to T. kingi from D. willistoni. Based on similarities in pathogen ultrastructure and the molecular information gained during this study, we propose that the microsporidium in H. convergens be given the name Tubulinosema hippodamiae.

P99. Paraxial T-box genes, Tbx6 and Tbx1, are required for cranial chondrogenesis and myogenesis

We previously reported that Tbx6, a T-box transcription factor expressed in nascent nonaxial mesoderm, is required for the differentiation of ventral body wall muscle and for segment formation and somitic muscle differentiation in Xenopus laevis . Here, we show that Tbx6 is also involved, at later stages, in cartilage differentiation from the cranial neural crest and head muscle development. In Tbx6 knockdown embryos, the cranial neural crest was shown to be correctly induced at the border of the neural plate and migrated in a slightly delayed manner, but finally reached positions in the pharyngeal arches nearly identical to those in the normal embryos as revealed by in situ hybridization and the neural crest-transplantation experiments. However, the neural crest cells failed to maintain Sox9 expression. In order to clarify the reasons why Tbx6 knockdown affects the development of head and pharyngeal muscles and cartilages, we noticed on Tbx1, another T-box gene expressed in more anterior paraxial structures, and a gene responsible for human DiGeorge syndrome, as a candidate to mediate Tbx6 function. Tbx6 knockdown reduced the expression of Tbx1. Next, Tbx1 knockdown caused phenotypes milder but similar to those of Tbx6 morphants, including reduced formation of head muscles and cartilages, and attenuated Sox9 expression. Furthermore, the phenotypes caused by Tbx6 knockdown were partially rescued by Tbx1 plasmid injection. Tbx6 expression in Tbx1 knockdown embryos was not reduced at all, but rather expanded in anterior direction, suggesting that Tbx6 is epistatic to Tbx1. This expansion of Tbx6 expression in Tbx1 morphants, when considered together with the fact that there was a gap between the anterior Tbx1-expressing and posterior Tbx6-expressing areas in normal neurula to early tailbud embryos, implys the presence of interaction between the anterior and posterior paraxial mesodermal tissues. These results suggest that Tbx6 is involved in the cranial cartilage and head muscle development by regulating anterior paraxial genes such as Tbx1 and Sox9.

Morphology and Taxonomic Status of Two Little-Known Nematode Species Parasitizing North American Fishes

Examination of some freshwater and brackishwater (estuarine) fishes in South Carolina in October 2009 yielded, in addition to other parasites, 2 little-known nematode species identified as Dichelyne fastigatus Chandler, 1935 (Cucullanidae), from the red drum, Sciaenops ocellatus (Linnaeus), from an estuary, and Rhabdochona ovifilamenta Weller, 1938 (Rhabdochonidae), from the shorthead redhorse, Moxostoma macrolepidotum (Lesueur), from Lake Moultrie. Light and scanning electron microscopy (the latter used for the first time for these species) made it possible to describe several important, but previously unreported, taxonomic features in D. fastigatus, such as the location of the excretory pore and deirids, the shape of deirids and a gubernaculum, the shape and size of eggs, the presence of precloacal ventral oblique muscle bands, and 11 pairs of caudal papillae and a pair of phasmids. It distinctly differs from the most similar Dichelyne cotylophora (Ward and Magath, 1917), a parasite of North American freshwater percids, in the number and arrangement of postanal papillae and by a markedly elevated cloacal region. Records of Dichelyne lintoni Barreto, 1922, from S. ocellatus probably concern D. fastigatus. Examination of R. ovifilamenta revealed a high degree of morphologic and biometric variability in this species. Based on our analysis, Rhabdochona laurentiana Lyster, 1940 , Rhabdochona milleri Choquette, 1951, and Rhabdochona catostomi Kayton, Kritsky, and Tobias, 1979, are synonymized with R. ovifilamenta Weller, 1938, typically a parasite of North American catostomids.

Contraction of the Ventral Abdomen Potentiates Extracardiac Retrograde Hemolymph Propulsion in the Mosquito Hemocoel

BackgroundHemolymph circulation in mosquitoes is primarily controlled by the contractile action of a dorsal vessel that runs underneath the dorsal midline and is subdivided into a thoracic aorta and an abdominal heart. Wave-like peristaltic contractions of the heart alternate in propelling hemolymph in anterograde and retrograde directions, where it empties into the hemocoel at the terminal ends of the insect. During our analyses of hemolymph propulsion in Anopheles gambiae, we observed periodic ventral abdominal contractions and hypothesized that they promote extracardiac hemolymph circulation in the abdominal hemocoel.Methodology/Principal FindingsWe devised methods to simultaneously analyze both heart and abdominal contractions, as well as to measure hemolymph flow in the abdominal hemocoel. Qualitative and quantitative analyses revealed that ventral abdominal contractions occur as series of bursts that propagate in the retrograde direction. Periods of ventral abdominal contraction begin only during periods of anterograde heart contraction and end immediately following a heartbeat directional reversal, suggesting that ventral abdominal contractions function to propel extracardiac hemolymph in the retrograde direction. To test this functional role, fluorescent microspheres were intrathoracically injected and their trajectory tracked throughout the hemocoel. Quantitative measurements of microsphere movement in extracardiac regions of the abdominal cavity showed that during periods of abdominal contractions hemolymph flows in dorsal and retrograde directions at a higher velocity and with greater acceleration than during periods of abdominal rest. Histochemical staining of the abdominal musculature then revealed that ventral abdominal contractions result from the contraction of intrasegmental lateral muscle fibers, intersegmental ventral muscle bands, and the ventral transverse muscles that form the ventral diaphragm.Conclusions/SignificanceThese data show that abdominal contractions potentiate extracardiac retrograde hemolymph propulsion in the abdominal hemocoel during periods of anterograde heart flow.

Functional Diversity of ESC-Derived Motor Neuron Subtypes Revealed through Intraspinal Transplantation

Cultured ESCs can form different classes of neurons, but whether these neurons can acquire specialized subtype features typical of neurons in vivo remains unclear. We show here that mouse ESCs can be directed to form highly specific motor neuron subtypes in the absence of added factors, through a differentiation program that relies on endogenous Wnts, FGFs, and Hh-mimicking the normal program of motor neuron subtype differentiation. Molecular markers that characterize motor neuron subtypes anticipate the functional properties of these neurons in vivo: ESC-derived motor neurons grafted isochronically into chick spinal cord settle in appropriate columnar domains and select axonal trajectories with a fidelity that matches that of their in vivo generated counterparts. ESC-derived motor neurons can therefore be programmed in a predictive manner to acquire molecular and functional properties that characterize one of the many dozens of specialized motor neuron subtypes that exist in vivo.

Total lipid content, fatty acid and mineral compositions of muscles and liver in wild and farmed sea bass (Dicentrarchus labrax)

The fatty acid and mineral compositions in the dorsal and ventral muscles and liver of wild and farmed sea bass (Dicentrarchus labrax) were evaluated. The farmed animals showed a significant higher fat content (p < 0.05) than the wild ones, for all studied samples. The percentages of SFA and PUFA as well as the n-6/n-3 were higher (p < 0.05) in the muscle in wild compared with farmed sea bass. However, in liver, SFA and MUFA were concentrated in wild fish. Among n-3 PUFA both fish were good sources of EPA and DHA. The results revealed also that levels of trace elements varied depending on different tissues in both fish (p < 0.05). Potassium, calcium and magnesium were concentrated in muscles compared with liver, in both fish, whereas iron, zinc, copper and manganese concentrations were higher in liver than in muscle tissue (p < 0.05). Key words: Family Moronidae, Dicentrarchus labrax, essential minerals, fatty acids, EPA, DHA.

Call properties and morphology of the sound-producing organ in Ophidion rochei (Ophidiidae)

The anatomical structures of the sound-producing organ in Ophidion rochei males present an important panel of highly derived characters: three pairs of putatively slow sonic muscles; a neural arch that pivots; a rocker bone at the front pole of the swimbladder; a stretchable swimbladder fenestra; a swimbladder plate; and an internal cone that terminates in a pair of membranes in the caudal swimbladder. Male courtship calls are produced nocturnally and consist of trains of 10 to 40 pulses that increase in amplitude and decrease in rate before exhibiting alternating periods of ca. 84 and 111 ms. Each pulse includes an unusual waveform with two parts. Pulse part 1 is a single cycle followed by a longer duration pulse part that exhibits gradual damping. Sounds and morphology suggest two hypotheses on the sound-producing mechanism. The 'pulley' hypothesis would require an alternate contraction of the ventral and dorsal muscles to form the two parts of each pulse. The 'bow' hypothesis involves a release mechanism with the sustained contraction of the dorsal muscle during all of the call, and the rapid contraction/relaxation of the ventral muscle to form each pulse.

COMPARISON OF MEAT QUALITY RELATED CHEMICAL COMPOSITIONS OF WILD-CAPTURED AND CAGE-CULTURED COBIA

Nine wild-captured cobia (Rachycentron canadum) and the compatible number and size of cultured cobia from two cagecultured sites, namely Penghu (PH) and Pingtung (PT) Counties, were sampled for chemical analyses. The condition factor of wild cobia was significantly lower than those of cultured fish. The wild cobia had higher moisture content than that of the cultured one, while fat contents in both dorsal and ventral muscles of the former were significantly lower than those of the latter. There were no significant differences between cultured and wild cobia in protein and ash contents. The total free amino acids (FAAs) contents in cultured cobia from two different localities were higher than those of wild fish. Taurine was the most prominent FAA in wild cobia, while glycine was more prominent in cultured fish than in the wild one. Lysine contents were significantly the highest in both dorsal and ventral muscles in PH-cultured cobia. The contents of glutamic acid, glutamine, alanine, ornithine and proline in cultured cobia were higher than those in wild cobia. There was no significant difference between wild and cultured cobia in anserine content, while carnosine was detected only in wild cobia. Inosine monophosphate was the major component in ATP-related compounds in both wild and cultured cobia, but no significant difference in its levels between the wild and cultured groups was found. The contents of ammonia was higher in PH-cultured cobia than those in both PT-cultured and wild cobia, yet no significant difference in urea content of both D and V muscles among the three groups.