Modulation of redox regulatory molecules and electron transport chain activity in muscle of air breathing fish Heteropneustes fossilis under air exposure stress

Responses of redox regulatory system to long-term survival (> 18 h) of the catfish Heteropneustes fossilis in air are not yet understood. Lipid and protein oxidation level, oxidant (H2O2) generation, antioxidative status (levels of superoxide dismutase, catalase, glutathione peroxidase and reductase, ascorbic acid and non-protein sulfhydryl) and activities of respiratory complexes (I, II, III and IV) in mitochondria were investigated in muscle of H. fossilis under air exposure condition (0, 3, 6, 12 and 18 h at 25 A degrees C). The increased levels of both H2O2 and tissue oxidation were observed due to the decreased activities of antioxidant enzymes in muscle under water deprivation condition. However, ascorbic acid and non-protein thiol groups were the highest at 18 h air exposure time. A linear increase in complex II activity with air exposure time and an increase up to 12 h followed by a decrease in activity of complex I at 18 h were observed. Negative correlation was observed for complex III and V activity with exposure time. Critical time to modulate the above parameters was found to be 3 h air exposure. Dehydration induced oxidative stress due to modulation of electron transport chain and redox metabolizing enzymes in muscle of H. fossilis was clearly observed. Possible contribution of redox regulatory system in muscle tissue of the fish for long-term survival in air is elucidated. Results of the present study may be useful to understand the redox metabolism in muscle of fishes those are exposed to air in general and air breathing fishes in particular.

Muscle wasting in myotonic dystrophies: a model of premature aging

Myotonic dystrophy type 1 (DM1 or Steinert's disease) and type 2 (DM2) are multisystem disorders of genetic origin. Progressive muscular weakness, atrophy and myotonia are the most prominent neuromuscular features of these diseases, while other clinical manifestations such as cardiomyopathy, insulin resistance and cataracts are also common. From a clinical perspective, most DM symptoms are interpreted as a result of an accelerated aging (cataracts, muscular weakness and atrophy, cognitive decline, metabolic dysfunction, etc.), including an increased risk of developing tumors. From this point of view, DM1 could be described as a progeroid syndrome since a notable age dependent dysfunction of all systems occurs. The underlying molecular disorder in DM1 consists of the existence of a pathological (CTG) triplet expansion in the 3' untranslated region (UTR) of the Dystrophia ll/Iyotonica Protein Kinase (DMPK) gene, whereas (CCTG)n repeats in the first intron of the Cellular Nucleic acid Binding Protein/Zinc Finger Protein 9 (CNBP/ZNF9) gene cause DM2. The expansions are transcribed into (CUG)n and (CCUG)n-containing RNA, respectively, which form secondary structures and sequester RNA binding proteins, such as the splicing factor muscleblind-like protein (MBNL), forming nuclear aggregates known as foci. Other splicing factors, such as CUGBP, are also disrupted, leading to a spliceopathy of a large number of downstream genes linked to the clinical features of these diseases. Skeletal muscle regeneration relies on muscle progenitor cells, known as satellite cells, which are activated after muscle damage, and which proliferate and differentiate to muscle cells, thus regenerating the damaged tissue. Satellite cell dysfunction seems to be a common feature of both age-dependent muscle degeneration (sarcopenia) and muscle wasting in DM and other muscle degenerative diseases. This review aims to describe the cellular, molecular and macrostructural processes involved in the muscular degeneration seen in DM patients, highlighting the similarities found with muscle aging.

Human muscle spindles act as forward sensory models.

Modern theories of motor control incorporate forward models that combine sensory information and motor commands to predict future sensory states. Such models circumvent unavoidable neural delays associated with on-line feedback control. Here we show that signals in human muscle spindle afferents during unconstrained wrist and finger movements predict future kinematic states of their parent muscle. Specifically, we show that the discharges of type Ia afferents are best correlated with the velocity of length changes in their parent muscles approximately 100-160 ms in the future and that their discharges vary depending on motor sequences in a way that cannot be explained by the state of their parent muscle alone. We therefore conclude that muscle spindles can act as "forward sensory models": they are affected both by the current state of their parent muscle and by efferent (fusimotor) control, and their discharges represent future kinematic states. If this conjecture is correct, then sensorimotor learning implies learning how to control not only the skeletal muscles but also the fusimotor system.

Survey of biosystematic and sexual reproductive physiology in Holothuroidea on Hormozgan Province

Sea cucumbers belong to phylum Echinodermata, order Holothuroidea are an abundant and diverse group of Invertebrates, with over 1400 species occuring from the intertidal to the deepest oceanic trenches. Sea cucumbers are important components of the food chain in temperate and coral reef ecosystems and they play an important role as deposite feeders and suspension feeders. Rapid decline in populations may have serious consequences for the survival of other species that are part of the same complex food web,as the eggs, larve and juveniles constitute an important food source for the other marine species including crustaceans, fish and mollusks. In addition sea cucumbers are often called the earthworms of the sea, because they are responsible for the extensive shifting and mixing of the substrate, and recycling of detrital matter. Sea cucumbers consume and grind sediment and organic material into finer particles , turning over the top layers of sediment in lagoons , reefs and other habitats and allowing the penetration of oxygen. While the taxonomy of the holothurian families is generally well known , the distinction of similar species is difficult. There are relatively few holothurian taxonomist.Most sea cucumber species can be identified by Holothurin taxonomists by using the calcareous skeletal ossicles found in the body wall. In this study , at first a sea cucumber from Kish island in Persian gulf has recognized. Individuals collected from west and east extend far away into north and south of coral reefs by diving. I have checked them morphologically and anatomically.Then with key to the orders of the Holothuroidea, They belong to the Aspidochirotida with key to the families of Aspidochirotida, they were in Stichopodidae families and with key to the genus of Stchopodidae, they were Stichopus. Then ossicles were extracted at National Museum of Natural History, by Dr David Pawson. The ossicles were measured on a transect across a slide prepared from the mid-dorsal region of each specimen.The one we have in the shallow waters of Kish island, is Stichopus hermanni, a massive holothurian, body broad, considerably flattened ventraly ,the dorsal side slightly arched and the lateral sides almost vertical; body wall fairy thick and soft ; mouth subterminal; anus central; tentacles usually 20 in number of length and leaf shaped. Numerous ossicles consisting of table with large discs having usually 7 to 15 peripheral holes, but often irregular or incomplete and spire of moderate height ending in a group of spinelets, rosettes of variable development, and c-shaped rods. Color (exept papillae)partly remained after preservation in alcohol which is found at the depth of 4 to 8 meters, on coral reef. Furthermore, the sexual reproductive cycle was described using standard methods. Gonads were removed and transferred to Bouin's fixative for four weeks and then processed according to standard embedding technique. To prevent the loss of tubule contents during embedding, the tubule sections, were cut well beyond the segment selected for sectioning. For each individual, six sections, each section with 5µm diameter by microtome were cut from tubules. These sections were first placed on gelatin coated slides (the gelatin was heated to 42°c) and then transferred to the oven at 37°c for one hour. This technique usually prevents the fragil tubules from breaking and the loss of gametes. The slides were stained with Eosin and Hematoxylin, and good resolution of the various cell types achieved.A second series of slides was stained with the Periodic Acid Schiff(PAS) to identify polysaccharides(glycogen). Monthly sampling was occurred.The sexual reproductive cycle was defined through the combined use of these criteria: Monthly percentages of the gonad stages for each sex, the monthly gonad index (GI) , given as the ratio of the wet gonad weight (G) to the dray weight (DW)and the monthly percentage of individuals that undetermined sex. The gonad consists of two tufts of tubules on which saccules develop. Gonadal development was classified into five stages: post spawning, recovery, growth, advanced growth, and mature stage that were adapted from the earlier studies of holothurians. Histological preparations showed that the sex of larger individuals could be identified by the presence of oogonia and young oocytes in females, and spermatogonic stages in males.The mean diameter of the tubules and gonadal mass follow annual cycles, increasing from late winter through spring, and dropping abruptly after spawning in the summer. Gametogenesis is generally a prolongate process and begins in March. By summer the ovarian tubules contain oocytes with diameter of 120-240 pm and the testicular tubules contain an abundance of spermatozoa (diameter 5-6 gm ).Following spawning the predominant activity within the spent tubules is phagocytosis of the residual gamets.The active phase of gametogenesis (March to July), coincides with an increasing photoperiod regim, and an accelerated gametogenesis occurs in July when temperature is high. Throughout the year, the gonad of Stichopus hermanni is larger in males than in females, and this is due to the number of tubules in the testis rather than to tubules length or diameter.

Reproductive physiology of ribbon fish (Trichiurus lepturus)

The ribbon fishes ‘of the family Trichiuridac are represented as one of the most important food resources in Indian ocean. High density of the dominant species of ribbon fish (Trichiurus lepturus) in Oman sea and the 'Tillable catch in last yeas (more than 7000 tones per year) makes a trust area for studing their population biolog and stock assessment. As our knowledge on reproductive biology of this species has an important role on their fisheries management, as well as conservation of this stock from decline or over fishing, this research was held to determine some aspects of reproductive physiology of ribbon fish and the effects of environmental factors in gonadal cycle. The goals of the present thesis is to determine some aspects of reproductive physiology such as gonadosomatic index (GSI) , hepatosomatic index (HSI), condition factor (Ko, fecundity, sex ratio, size at first maturity, size at maturity (LM5O) and their relative hormonal & biochemical fluctuations. In this regards annual variation of sex hormones ic. estradiol 17-B, progestron, cortisol, testostrone and gonadotropins FSH (GTH-I) , LH (GTH-ll)I were measured ; gonadal histological studies were done by light & electron micrography. The research was carried out from April 1995 to January 19% in Ras Nleidani in the north part of Oman sea, and the environmental factors such as temperature, salinity, oxygen, rainfall and pH were measured. The effects of these parameters on reproductive cycle and hormonal fluctuationswere discussed by using correlation and principle component analysis (PCA). Female Ribbon fish reproductive strategy shows the same paterns of nonguarder marine teleosts. T. lepturus has more than one spawning season (existance of egges in different size in each month) and therfore it must have asynchronous ovaries and belong to continious spawners. GSI and HSI are good evidences for this type of reproductive patern. The testis of the lobular type , which is typical of most teleosts , is composed of numerous lobules which are separated from each other by a thin layer of fibrous connective tissue. GSI fluctuations revealed prolong- spawning time in males. There is significant increase in 17-13 estradiol. progestrone , cortisol and gonadotropins with maturity and prespawning period of female T lepturus. Plasma concentration of E2 and GTH II incresaed along with water temperature increasing (3300).. Spawning was observed from Nov. 1995 to Apr. 1996 in this species. Progestrone increased significantly with increasing rainfall in this season (P<0.01). Plasma cortisol levels increased with maturation and vitelpgenesis and also with the peak of spawning. From lenght-weight frequency and size distribution in each age groups and also minimum size at first maturity (52a cm) it would he concluded that T. lepturus must be matured at 2 years of age. Serum cholestrol and triglicerides significantly increased when maturation occured in this species. The relationship between alkaline phosphatase activity and hormonal fluctuations with maturity and vitelogenesis were discussed. Proximate compostion (muscle) shows significant variation with spawning period and maturity. Absolute individual fecundity (17420-159150) increased with body length and weight. Ultrastructural observations show dramatic variation in cell membrane (0ocyte membrane), yolk vesicles and, nucleolus dispersal in relation to maturity stages. fluctuations of gonadal hormones were discused in relation with vitelogenesis. Testosterone increased in males from Nov: to Mar. due to environmental impacts and spawning time. Sex ratio in different depth (10-40 m ,80-110 m) shows significnt differences in this ratio for two depths. In 10-40 m depth female shows dominant abundance to male in each months that may be due to their reproductive migration behaviour. The effects of temperature photoperiod and rainfall to maturity and spawning were discussed. According to -pawning period of T. leptunts in our sampling area it could be suggested that ribbon fish fi,theries must be restricted in the peak of spawning seasons (Feb. to Mar.) and in the spawning grounds (under 40 m depths). Other suggestions for population conservation have been mentioned.

Transducer and base compliance alter the in situ 6 dof force measured from muscle during an isometric contraction in a multi-joint limb.

Although musculoskeletal models are commonly used, validating the muscle actions predicted by such models is often difficult. In situ isometric measurements are a possible solution. The base of the skeleton is immobilized and the endpoint of the limb is rigidly attached to a 6-axis force transducer. Individual muscles are stimulated and the resulting forces and moments recorded. Such analyses generally assume idealized conditions. In this study we have developed an analysis taking into account the compliances due to imperfect fixation of the skeleton, imperfect attachment of the force transducer, and extra degrees of freedom (dof) in the joints that sometimes become necessary in fixed end contractions. We use simulations of the rat hindlimb to illustrate the consequences of such compliances. We show that when the limb is overconstrained, i.e., when there are fewer dof within the limb than are restrained by the skeletal fixation, the compliances of the skeletal fixation and of the transducer attachment can significantly affect measured forces and moments. When the limb dofs and restrained dofs are matched, however, the measured forces and moments are independent of these compliances. We also show that this framework can be used to model limb dofs, so that rather than simply omitting dofs in which a limb does not move (e.g., abduction at the knee), the limited motion of the limb in these dofs can be more realistically modeled as a very low compliance. Finally, we discuss the practical implications of these results to experimental measurements of muscle actions.

Is titin a 'winding filament'? A new twist on muscle contraction.

Recent studies have demonstrated a role for the elastic protein titin in active muscle, but the mechanisms by which titin plays this role remain to be elucidated. In active muscle, Ca(2+)-binding has been shown to increase titin stiffness, but the observed increase is too small to explain the increased stiffness of parallel elastic elements upon muscle activation. We propose a 'winding filament' mechanism for titin's role in active muscle. First, we hypothesize that Ca(2+)-dependent binding of titin's N2A region to thin filaments increases titin stiffness by preventing low-force straightening of proximal immunoglobulin domains that occurs during passive stretch. This mechanism explains the difference in length dependence of force between skeletal myofibrils and cardiac myocytes. Second, we hypothesize that cross-bridges serve not only as motors that pull thin filaments towards the M-line, but also as rotors that wind titin on the thin filaments, storing elastic potential energy in PEVK during force development and active stretch. Energy stored during force development can be recovered during active shortening. The winding filament hypothesis accounts for force enhancement during stretch and force depression during shortening, and provides testable predictions that will encourage new directions for research on mechanisms of muscle contraction.

Knockdown and overexpression of Unc-45b result in defective myofibril organization in skeletal muscles of zebrafish embryos

We thank John Stubblefield for editing, Junling Li for the assistance in the Western blot analysis. This research was supported by a training grant from National Institutes of Health (#T32 AR07592) and a research grant MB-8713-08 from United States - Israel Binational Agriculture Research and Development Fund.

Cloning and expression analysis of myogenin from flounder (Paralichthys olivaceus) and promoter analysis of muscle-specific expression

Myogenin is a bHLH transcription factor of the MyoD family. It plays a crucial role in myoblast differentiation and maturation. We report here the isolation of flounder myogenin gene and the characterization of its expression patterns. Sequence analysis indicated that flounder myogenin shared a similar structure and the conserved bHLH domain with other vertebrate myogenin genes. Flounder myogenin gene contains 3 exons and 2 introns. Sequence alignment and phylogenetic showed that flounder myogenin was more homologous with halibut (Hippoglossus hippoglossus) myogenin and striped bass (Morone saxatilis) myogenin. Whole-mount embryo in situ hybridization revealed that flounder myogenin was first detected in the medial region of somites that give rise to slow muscles, and expanded later to the lateral region of the somite that become fast muscles. The levels of myogenin transcripts dropped significantly in matured somites at the trunk region. Its expression could only be detected in the caudal somites, which was consistent with the timing of somite maturation. Transient expression analysis showed that the 546 bp flounder myogenin promoter was sufficient to direct muscle-specific GFP expression in zebrafish embryos. (c) 2007 Elsevier Inc. All rights reserved.

Molecular structure and expression patterns of flounder (Paralichthys olivaceus) Myf-5, a myogenic regulatory factor

Myf-5, a member of the myogenic regulatory factors (MRF), has been shown to be expressed in muscle precursors in early stage zebrafish embryos. The MRFs, including MyoD, Myf-5, Myogenin and MR-F4, belong to the basic Helix-Loop-Helix transcription factors that contain a conserved basic Helix-Loop-Helix (bHLH) domain. To better understand the role of Myf-5 in the development of fish muscles, we have isolated the Myf-5 genomic sequence and cDNA from Flounder (Paralichthys olivaceus), and analyzed its structures and patterns of expression. Promoter analysis identified several putative transcription factor binding sites such as an E-box, NF-Y sites that might confer muscle-specific expression. Myf-5 transcripts were first detected in the paraxial mesoderm that gives rise to slow muscles. During somitogenesis, Myf-5 expression was found in developing somites. Myf-5 expression decreased gradually in somites in the anterior region, but remained strong in the newly formed somites. In the hatching stage, the expression was also detected in other muscle cells such as head muscle and fin muscle. In the growing fish, RT-PCR results showed that Myf-5 was expressed in the skeletal muscle and intestine. (c) 2006 Elsevier Inc. All rights reserved.

Characterization of muscle-regulatory gene, MyoD, from flounder (Paralichthys olivaceus) and analysis of its expression patterns during embryogenesis

Specification and differentiation of skeletal muscle cells are driven by the activity of genes encoding members of the myogenic regulatory factors (MRFs). In vertebrates, the MRF family includes MyoD, Myf5, myogenin, and MRF4. The MRFs are capable of converting a variety of nonmuscle cells into myoblasts and myotubes. To better understand their roles in fish muscle development, we isolated the MyoD gene from flounder (Paralichthys olivaceus) and analyzed its structure and patterns of expression. Sequence analysis showed that flounder MyoD shared a structure similar to that of vertebrate MRFs with three exons and two introns, and its protein contained a highly conserved basic helix-loop-helix domain (bHLH). Comparison of sequences revealed that flounder MyoD was highly conserved with other fish MyoD genes. Sequence alignment and phylogenetic analysis indicated that flounder MyoD, seabream (Sparus aurata) MyoD1, takifugu (Takifugu rubripes) MyoD, and tilapia (Oreochromis aureus) MyoD were more likely to be homologous genes. Flounder MyoD expression was first detected as two rows of presomitic cells in the segmental plate. From somitogenesis, MyoD transcripts were present in the adaxial cells that give rise to slow muscles and the lateral somitic cells that give rise to fast muscles. After 30 somites formed, MyoD expression decreased in the somites except the caudal somites, coincident with somite maturation. In the hatching stage, MyoD was expressed in other muscle cells and caudal somites. It was detected only in muscle in the growing fish.

Genes and the ageing muscle: a review on genetic association studies

Western populations are living longer. Ageing decline in muscle mass and strength (i.e. sarcopenia) is becoming a growing public health problem, as it contributes to the decreased capacity for independent living. It is thus important to determine those genetic factors that interact with ageing and thus modulate functional capacity and skeletal muscle phenotypes in older people. It would be also clinically relevant to identify 'unfavourable' genotypes associated with accelerated sarcopenia. In this review, we summarized published information on the potential associations between some genetic polymorphisms and muscle phenotypes in older people. A special emphasis was placed on those candidate polymorphisms that have been more extensively studied, i.e. angiotensin-converting enzyme (ACE) gene I/D, α-actinin-3 (ACTN3) R577X, and myostatin (MSTN) K153R, among others. Although previous heritability studies have indicated that there is an important genetic contribution to individual variability in muscle phenotypes among old people, published data on specific gene variants are controversial. The ACTN3 R577X polymorphism could influence muscle function in old women, yet there is controversy with regards to which allele (R or X) might play a 'favourable' role. Though more research is needed, up-to-date MSTN genotype is possibly the strongest candidate to explain variance among muscle phenotypes in the elderly. Future studies should take into account the association between muscle phenotypes in this population and complex gene-gene and gene-environment interactions.

McArdle disease: a unique study model in sports medicine

McArdle disease is arguably the paradigm of exercise intolerance in humans. This disorder is caused by inherited deficiency of myophosphorylase, the enzyme isoform that initiates glycogen breakdown in skeletal muscles. Because patients are unable to obtain energy from their muscle glycogen stores, this disease provides an interesting model of study for exercise physiologists, allowing insight to be gained into the understanding of glycogen-dependent muscle functions. Of special interest in the field of muscle physiology and sports medicine are also some specific (if not unique) characteristics of this disorder, such as the so-called 'second wind' phenomenon, the frequent exercise-induced rhabdomyolysis and myoglobinuria episodes suffered by patients (with muscle damage also occurring under basal conditions), or the early appearance of fatigue and contractures, among others. In this article we review the main pathophysiological features of this disorder leading to exercise intolerance as well as the currently available therapeutic possibilities.

Muscle function and body composition profile in adolescents withrestrictive anorexia nervosa: Does resistance training help?

The aim of this study was to analyze the effects of short-term resistance training on the body composition profile and muscle function in a group of Anorexia Nervosa restricting type (AN-R) patients. The sample consisted of AN-R female adolescents (12.8 ± 0.6 years) allocated into the control and intervention groups (n¼18 each). Body composition and relative strength were assessed at baseline, after 8 weeks and 4 weeks following the intervention. Body mass index (BMI) increased throughout the study (p = 0.011). Significant skeletal muscle mass (SMM) gains were found in the intervention group (p = 0.045, d = 0.6) that correlated to the change in BMI (r = 0.51, p < 0.031). Meanwhile, fat mass (FM) gains were significant in the control group (p = 0.047, d = 0.6) and correlated (r > 0.60) with change in BMI in both the groups. Significant relative strength increases (p < 0.001) were found in the intervention group and were sustained over time.

Xanthine oxidase pathway and muscle damage: Insights from McArdle disease

The intent of this review is to summarize current body of knowledge on the potential implication of the xanthine oxidase pathway (XO) on skeletal muscle damage. The possible involvement of the XO pathway in muscle damage is exemplified by the role of XO inhibitors (e.g., allopurinol) in attenuating muscle damage. Reliance on this pathway (as well as on the purine nucleotide cycle) could be exacerbated in conditions of low muscle glycogen availability. Thus, we also summarize current hypotheses on the etiology of both baseline and exertional muscle damage in McArdle disease, a condition caused by inherited deficiency of myophosphorylase. Because myophosphorylase catalyzes the first step of muscle glycogen breakdown, patients are unable to obtain energy from their muscle glycogen stores. Finally, we provide preliminary data from our laboratory on the potential implication of the XO pathway in the muscle damage that is commonly experienced by these patients.