Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.6.4.1 (myosin ATPase)
1,140 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

At birth, the locomotor muscles of precocial, terrestrial mammals are similar to those of adults in both mass, as a percent of total body mass, and fiber-type composition. It is hypothesized that bottlenose dolphins (Tursiops truncatus), marine mammals that swim from the instant of birth, will also exhibit precocial development of locomotor muscles. Body mass data from neonatal and adult dolphins are used to calculate Grand's (1992) Neural and Muscular Indices of Development. Using these indices, the bottlenose dolphin is a Condition "3.5" neonate, where Condition 4 is the documented extreme of precocial development in terrestrial mammals. Moreover, myosin ATPase (alkaline preincubation) analyses of the epaxial locomotor m. extensor caudae lateralis show that neonatal dolphins have fiber-type profiles very similar to those of adults. Thus, based on mass and myosin ATPase activity, muscle development in dolphins is precocial. However, succinic dehydrogenase and Nile red histochemistry demonstrate that neonatal dolphin muscle has mitochondrial and lipid distributions different from those found in adults. These data suggest that neonates have a lower aerobic capacity than adults. Dolphin neonates may compensate for an apparent lack of aerobic stamina in two ways: 1) by being positively buoyant, with a relatively increased investment of their total body mass in blubber, and 2) by "free-riding" off their mothers. This study investigates quantitatively the development of a dolphin locomotor muscle and offers suggestions about adaptations required for a completely aquatic existence.
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PMID:Precocial development of axial locomotor muscle in bottlenose dolphins (Tursiops truncatus). 1081 3

Development of muscle is critically dependent on several hormones which in turn are regulated by nutritional status. We therefore determined the impact of mild postnatal undernutrition on key markers of myofibre function: type I slow myosin heavy chain (MyHC) isoform, myosin ATPase, succinate dehydrogenase and alpha-glycerophosphate dehydrogenase. In situ hybridization, immunocytochemistry and enzyme histochemistry were used to assess functionally distinct muscles from 6-week-old pigs which had been fed an optimal (6% (60 g food/kg body weight per d)) or low (2% (20 g food/kg per d)) intake for 3 weeks, and kept at 26 degrees C. Nutritional status had striking muscle-specific influences on contractile and metabolic properties of myofibres, and especially on myosin isoform expression. A low food intake upregulated slow MyHC mRNA and protein levels in rhomboideus by 53% (P < 0.01) and 18% (P < 0.05) respectively; effects in longissimus dorsi, soleus and diaphragm were not significant. The oxidative capacity of all muscles increased on the low intake, albeit to varying extents: longissimus dorsi (55%), rhomboideus (30%), soleus (21%), diaphragm (7%). Proportions of slow oxidative fibres increased at the expense of fast glycolytic fibres. These novel findings suggest a critical role for postnatal nutrition in regulating myosin gene expression and muscle phenotype. They have important implications for optimal development of human infants: on a low intake, energetic efficiency will increase and the integrated response to many metabolic and growth hormones will alter, since both are dependent on myofibre type. Mechanisms underlying these changes probably involve complex interactions between hormones acting as nutritional signals and differential effects on their cell membrane receptors or nuclear receptors.
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PMID:Postnatal regulation of myosin heavy chain isoform expression and metabolic enzyme activity by nutrition. 1102 69

The lizard family Phrynosomatidae comprises three subclades: the closely related sand and horned lizards, and their relatives the Sceloporus group. This family exhibits great variation in ecology, behavior, and general body plan. Previous studies also show that this family exhibits great diversity in locomotor performance abilities; as measured on a high-speed treadmill, sand lizards are exceptionally fast sprinters, members of the Sceloporus group are intermediate, and horned lizards are slowest. These differences are paralleled by differences in relative hindlimb span. To determine if muscle fiber-type composition also varies among the three subclades, we examined the iliofibularis (IF), a hindlimb muscle used in lizard locomotion, in 11 species of phrynosomatid lizards. Using histochemical assays for myosin ATPase, an indicator of fast-twitch capacity, and succinic dehydrogenase, denoting oxidative capacity, we classified fiber types into three categories based on existing nomenclature: fast-twitch glycolytic (FG), fast-twitch oxidative-glycolytic (FOG), and slow-twitch oxidative (SO). Sand lizards have a high proportion of FG fibers (64-70%) and a low proportion of FOG fibers (25-33%), horned lizards are the converse (FG fibers 25-31%, FOG fibers 56-66%), and members of the Sceloporus group are intermediate for both FG (41-48%) and FOG (42-45%) content. Hence, across all 11 species %FOG and %FG are strongly negatively correlated. Analysis with phylogenetically independent contrasts indicate that this negative relationship is entirely attributable to the divergence between sand and horned lizards. The %SO also varies among the three subclades. Results from conventional nested ANCOVA (with log body mass as a covariate) indicate that the log mean cross-sectional area of individual muscle fibers differs among species and is positively correlated with body mass across species, but does not differ significantly among subclades. The log cross-sectional area of the IF varies among species, but does not vary among subclades. Conversely, the total thigh muscle cross-sectional area does not vary among species, but does vary among subclades; horned lizards have slimmer thighs. Muscle fiber-type composition appears to form part of a coadapted suite of traits, along with relative limb and muscle sizes, that affect the locomotor abilities of phrynosomatid lizards.
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PMID:Comparative analysis of fiber-type composition in the iliofibularis muscle of phrynosomatid lizards (Squamata). 1174 64

To assess the effect of severe chronic obstructive pulmonary disease (COPD) on the ability of human diaphragmatic myofibers to aerobically generate ATP relative to ATP utilization, we obtained biopsy specimens of the costal diaphragm from seven patients with severe COPD (mean +/- SE; age 56 +/- 1 yr; forced expiratory volume in 1 s 23 +/- 2% predicted; residual volume 267 +/- 30% predicted) and seven age-matched control subjects. We categorized all fibers in these biopsies by using standard techniques, and we carried out the following quantitative histochemical measurements by microdensitometry: 1) succinate dehydrogenase (SDH) activity as an indicator of mitochondrial oxidative capacity and 2) calcium-activated myosin ATPase (mATPase) activity, the ATPase that represents a major portion of ATP consumption by contracting muscle. We noted the following: 1) COPD diaphragms had a larger proportion of type I fibers, a lesser proportion of type IIax fibers, and the same proportion of type IIa fibers as controls. 2) SDH activities of each of the fiber types were higher in COPD than control diaphragms (P < 0.0001); the mean increases (expressed as percent of control values) in types I, IIa, and IIax were 84, 114, and 130%, respectively. 3) COPD elicited no change in mATPase activity of type I and IIa fibers, but mATPase decreased in type IIax fibers (P = 0.02). 4) Mitochondrial oxidative capacity relative to ATP demand (i.e., SDH/mATPase) was higher (P = 0.03) in each of the fiber types in COPD diaphragms than in controls. These results demonstrate that severe COPD elicits an increase in aerobic ATP generating capacity relative to ATP utilization in all diaphragmatic fiber types as well as the previously described fast-to-slow fiber type transformation (Levine S, Kaiser L, Leferovich J, and Tikunov B, N Engl J Med 337: 1799-1806, 1997).
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PMID:Bioenergetic adaptation of individual human diaphragmatic myofibers to severe COPD. 1184 60

Mitochondrial ATPase and myosin ATPase have been localized in the muscle fibers of the rat diaphragm. The principal fiber type possesses a structure favorable for making this cytochemical separation with the light microscope. This small red fiber has numerous large, nearly spherical, mitochondria (ca. 1.5 micro) which are aggregated beneath the sarcolemma. In the interior of the fiber, smaller paired filamentous mitochondria (ca. 0.2 micro diameter) are aligned with the I band. Distribution of mitochondria was determined by sudanophilia, succinic dehydrogenase activity, and by direct examination with the electron microscope. ATPase activity at pH 7.2 is located in the large peripheral mitochondria and in the smaller mitochondria associated with the I band. The alignment of the small mitochondria results in a discrete cross-striated appearance in fibers stained for this enzymic activity. This mitochondrial ATPase does not cleave adenosine diphosphate or adenosine monophosphate; it is not sulfhydryl dependent and, in fact, is enhanced by the mercurial, p-hydroxymercuribenzoate. It requires magnesium ion and is stimulated by dinitrophenol. It is inhibited after formol-calcium fixation, but the residual activity is demonstrable by lengthening the incubation time. At pH 9.4 the ATPase is myofibrillar in origin and is located in the A bands. This myosin ATPase activity is sulfhydryl-dependent. Mercurial at this high pH has an interesting dual effect: it suppresses myosin ATPase but evokes mitochondrial ATPase activity. A third type of ATPase activity can be demonstrated, especially in the large white fibers. This activity occurs at pH 7.2 in the presence of cysteine. Its position is manifested cytochemically as a fine reticular pattern which surrounds individual myofibrils. The distribution suggests that it may originate in the sarcoplasmic reticulum.
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PMID:Cytochemical studies of adenosine triphosphatases in skeletal muscle fibers. 1394 Oct 20

Throat fan (dewlap) extension is sexually dimorphic in green anole lizards (Anolis carolinensis). Males have larger dewlaps which they display more frequently than females. Correlated with the behavior, sexual dimorphisms occur in the skeletal, muscular and neural structures responsible for dewlap extension in green anoles. We used histochemical techniques to stain for myosin ATPase and succinate dehydrogenase (SDH) to determine whether sex differences also exist in fiber type composition of the ceratohyoideus, the muscle that extends the dewlap. Based on the staining pattern for the two enzymes, four fiber types were identified: fast-oxidative-glycolytic (FOG), fast-glycolytic (FG), slow-oxidative (SO), and tonic. In the ceratohyoideus of both sexes, the predominate fiber types were FOG (approximately 43%) and FG (approximately 34%). Also in both males and females, the FOG and FG fibers had approximately twice the cross-sectional area of the SO and tonic fibers. No sex differences occurred in the percentages of FOG and FG fibers. However, males had a greater percentage of tonic fibers than females, whereas females had a greater percentage of SO fibers than males. The high proportion of FOG fibers in the anole ceratohyoideus makes it similar to other relatively fatigue-resistant muscles used in movements of moderate speed and duration. Although the precise role of tonic fibers in dewlap extension is not known, the greater percentage of these fibers in the male ceratohyoideus might be required to stabilize or maintain extension of the large dewlap apparatus in males.
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PMID:Fiber type composition of the muscle responsible for throat fan extension in green anole lizards. 1505 65

Previously, we found that phrynosomatid lizards, a diverse group common in the southwestern USA, vary markedly in fiber-type composition of the iliofibularis (a hindlimb muscle important in locomotion). Phrynosomatidae comprises three subclades: the closely related sand and horned lizards, and their relatives the Sceloporus group. The variation in muscle fiber-type composition for 11 phrynosomatid species is attributable mainly to differences between the sand- and horned-lizard subclades. Here, we expand the phrynosomatid database with three additional species and compare these results with data collected for 10 outgroup (distantly related) species. Our goal was to determine if the patterns found in Phrynosomatidae hold across a broader phylogenetic range of the extant lizards and to elucidate the evolution of muscle fiber-type composition and related traits. To allow for meaningful comparisons, data were collected from species that are primarily terrestrial and relatively small in size (3.5-65 g body mass). Results indicate that the fiber-type variation observed within the Phrynosomatidae almost spans the range of variation observed in our sample of 24 species from eight families. However, one species of Acanthodactylus (Lacertidae) had a consistent region of large tonic fibers (that did not stain darkly for either succinic dehydrogenase or myosin ATPase activity), a fiber-type only occasionally seen in the other 23 species examined. Many species have a large proportion of either fast-twitch glycolytic (FG; e.g. sand lizards and Aspidoscelis) or fast-twitch oxidative-glycolytic (FOG) fibers (e.g. horned lizards), with the slow-oxidative proportion occupying only 1-17% of the iliofibularis. Importantly, the negative relationship between FG and FOG composition observed in Phrynosomatidae appears to be a characteristic of lizards in general, and could lead to functional trade-offs in aspects of locomotor performance, as has previously been reported for Lacertidae. Reconstruction of ancestral trait values by use of phylogenetically based statistical methods indicates especially large changes in fiber-type composition during the evolution of horned lizards.
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PMID:Muscle fiber-type variation in lizards (Squamata) and phylogenetic reconstruction of hypothesized ancestral states. 1633 72

Mole rats of the Spalax ehrenbergi superspecies are blind subterranean rodents that live under fluctuating oxygen supply, reduced to a measured 6% O(2), and mostly probably lower, during the rainy season. Fiber typing of muscles of the neck (trapezius) and leg (gastrocnemius, quadriceps) using standard histochemical techniques (succinic dehydrogenase, myosin ATPase) showed that the muscle fibers of mole rats in natural settings, as well as after extended captivity, were predominantly type IIa. The same muscles in laboratory rats showed the full range of fiber types. In contrast, the hearts of the mole rats and the laboratory rats were very similar. Our results indicate that skeletal muscle in the mole rats appears to have evolved in response to specific environmental demands to permit intensive endurance burrowing activities under conditions of severe or chronic hypoxia.
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PMID:Adaptive features of skeletal muscles of mole rats (Spalax ehrenbergi) to intensive activity under subterranean hypoxic conditions. 1867 7

When a marine mammal dives, breathing and locomotion are mechanically uncoupled, and its locomotor muscle must power swimming when oxygen is limited. The morphology of that muscle provides insight into both its oxygen storage capacity and its rate of oxygen consumption. This study investigated the m. longissimus dorsi, an epaxial swimming muscle, in the long duration, deep-diving pygmy sperm whale (Kogia breviceps) and the short duration, shallow-diving Atlantic bottlenose dolphin (Tursiops truncatus). Muscle myoglobin content, fiber type profile (based upon myosin ATPase and succinate dehydrogenase assays), and fiber size were measured for five adult specimens of each species. In addition, a photometric analysis of sections stained for succinate dehydrogenase was used to create an index of mitochondrial density. The m. longissimus dorsi of K. breviceps displayed significantly a) higher myoglobin content, b) larger proportion of Type I (slow oxidative) fibers by area, c) larger mean fiber diameters, and d) lower indices of mitochondrial density than that of T. truncatus. Thus, this primary swimming muscle of K. breviceps has greater oxygen storage capacity, reduced ATP demand, and likely a reduced rate of oxygen consumption relative to that of T. truncatus. The locomotor muscle of K. breviceps appears able to ration its high onboard oxygen stores, a feature that may allow this species to conduct relatively long duration, deep dives aerobically.
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PMID:Locomotor muscle profile of a deep (Kogia breviceps) versus shallow (Tursiops truncatus) diving cetacean. 2335 98

The aim of this study is to type fibers from porcine longissimus dorsi (LD) muscles according to their distribution of myosin heavy chain (MHC) isoforms as well as to investigate fiber characteristics. Four pure types, including types I, IIA, IIX, and IIB were labeled and two hybrid fiber types were subdivided into type IIAX and IIXB by immunohistochemistry using four monoclonal antibodies. Porcine LD muscles were found to have 92.79 (number) and 92.10% (area) of pure type composition, while the composition of hybrid fibers was 8.22 (number) and 9.71% (area). The activities of myosin ATPase increased in the following order: type I, IIAX, IIA = IIX = IIB and IIXB. The succinate dehydrogenase and glycerol-3-phosphate dehydrogenase activities were higher in fiber types I and IIB, respectively. The characteristics of hybrid fibers were observed that their characteristics did not lie between the properties for their respective pure phenotypes.
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PMID:The characteristics of myosin heavy chain-based fiber types in porcine longissimus dorsi muscle. 2420 May 62


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