Morphological and histochemical characterization of the pectoral fin muscle of the stripped weakfish,Cynoscion guatucupa

The fibres of superficial and deep abductor muscles of the pectoral fins of the stripped weakfish, Cynoscion guatucupa have been studied using histochemical techniques: succinic dehydrogenase (SDH) for mitochondria, periodic acid–Schiff (PAS) for glycogen, myosin‐adenosintriphosphatase (mATPase) to identify different fibre types based on the contraction speed and modified ATPase to identify capillaries. The fibre diameters were measured, and the capillaries of the main fibre types – red, pink and white— were counted. The two muscles showed both macroscopically and microscopically two well‐differentiated zones with predominant white fibres. The area of insertion of muscles into the fin rays had red, pink and white fibres. The origin zone of the muscle into the bone was composed by white fibres only. Both zones of white muscle evidenced a mosaic of small, medium and large polygonal white fibres. Red, pink and white muscles showed a wide histochemical diversity of fibre subtypes. The area per peripheral capillary increased from the red to the white muscles. Due to the predominance of white fibres, the pectoral fins of C. guatucupa were mainly involved in rapid movements to stop/discontinue and stabilize the body during swimming.     

A histochemical study of the lateral muscles of five teleost species

A qualitative histochemical study has been made of the myotomal muscles of five teleost fish (glass fish, Chanda ranga; carp, Carassius carassius; coalfish, Gadus virens; black mollie, Molliensia sp. and grey mullet, Mugil cephalus ) . Three or four main fibre types were distinguished in these species on the basis of the distribution and relative activities of glycogen, lipid, aglycerophosphate dehydrogenase, phosphorylase, and succinic dehydrogenase. The so-called red and white fibre types were found to have similar histochemical properties to previously investigated species. All the species studied, with the exception of the glass fish, Chanda ranga , were found to have one or two types of pink fibre situated between the red and white fibre regions. In the carp, coalfish and mullet, the pink fibres were found to be composed of small and large diameter fibres which were similar to red and white fibres respectively, except for their staining for succinic dehydrogenase. Considerable differences were found in the relative amounts of pink muscles between species. Minor fibre components were found in several species. These consisted of very small diameter fibres which did not stain well with any of the histochemical procedures used. It is suggested that these fibres represent areas of continuing muscle growth. The results obtained are discussed in relation to the division of labour between myotomal muscles during swimming.     

Histochemical characterization of myotomal muscle in the grass pickerel, Esox americanus vermiculatus (LeSeuer), and the muskellunge, E. masquinongy (Mitchell)

A histochemical study of the myotomal muscles in the grass pickerel, Esox americanus vermiculatus , and the muskellunge, E. masquinongy , was performed using actomyosin ATPase and NADH diaphorase activities. Three fibre types, i.e., red, white and pink were distinguished on the basis of their enzyme activities. White muscle fibres comprised the bulk of the myotomal musculature. The relative proportion of red muscle fibres was greater in the caudal region than in more anterior regions of the body. Pink fibres formed only a few layers between red and white. These findings are discussed in relation to the possible functional significance of the muscle fibre types in swimming and feeding behaviour in these species.     

Muscle fibre types and metabolism in post-larval and adult stages of notothenioid fish

Summary A histochemical study was carried out on muscle fibre types in the myotomes of post-larval and adult stages of seven species of notothenioid fish. There was little interspecific variation in the distribution of muscle fibre types in post-larvae. Slow fibres (diameter range 15–60 m) which stained darkly for succinic dehydrogenase activity (SDHase) formed a superficial layer 1–2 fibres thick around the entire lateral surface of the trunk. In all species a narrow band of very small diameter fibres (diameter range 5–62 m), with only weak staining activity, occurred between the skin and slow fibre layer. These have the characteristics of tonic fibres found in other teleosts. The remainder of the myotome was composed of fast muscle fibres (diameter range 9–75 m), which stain weakly for SDHase, -glycerophosphate dehydrogenase, glycogen and lipid. Slow muscle fibres were only a minor component of the trunk muscles of adult stages of the pelagic species Champsocephalus gunnari and Pseudochaenichthys georgianus, consistent with a reliance on pectoral fin swimming during sustained activity. Of the other species examined only Psilodraco breviceps and Notothenia gibberifrons had more than a few percent of slow muscle in the trunk (20%–30% in posterior myotomes), suggesting a greater involvement of sub-carangiform swimming at cruising speeds. The ultrastructure of slow fibres from the pectoral fin adductor and myotomal muscles of a haemoglobinless (P. georgianus) and red-blooded species (P. breviceps), both active swimmers, were compared. Fibres contained loosely packed, and regularly shaped myofibrils numerous mitochondria, glycogen granules and occasional lipid droplets. Mitochondria occupied >50% of fibre volume in the haemoglobinless species P. georgianus, each myofibril was surrounded by one or more mitochondria with densely packed cristae. No significant differences, however, were found in mean diameter between fibres from red-blooded and haemoglobinless species. The activities of key enzymes of energy metabolism were determined in the slow (pectoral) and fast (myotomal) muscles of N. gibberifrons. In contrast to other demersal Antarctic fish examined, much higher glycolytic activities were found in fast muscle fibres, probably reflecting greater endurance during burst swimming.     

Muscle fine structure reflects ecotype in two nototheniids

The fine structure of swimming (pectoral) and myotomal (axial) skeletal muscle and myocardium of two species of Antarctic nototheniid fishes were studied by electron microscopy, comparing the cryopelagic Pagothenia borchgrevinki and the benthic Trematomus bernacchii . Mean fibre size varied by a factor of four among muscles within each species and may have reflected the locomotory power available, being larger in pectoral oxidative (red) and axial glycolytic (white) muscle of P. borchgrevinki . Both species use labriform locomotion, and the more active P. borchgrevinki had a greater capillary supply, expressed as a capillary to fibre ratio, than T. bernacchii to both red (3·48 ± 0·36 v . 1·63 ± 0·14, mean ±  s . e .; P  < 0·01) and white (2·70 ± 0·20 v . 1·53 ± 0·18, mean ±  s . e .; P  < 0·01) regions of the pectoral musculature. The greater aerobic scope of P. borchgrevinki was strikingly demonstrated in the higher mitochondrial content of all skeletal muscle types sampled, and the ventricular myocardium (0·269 ± 0·011 v . 0·255 ± 0·012 mean ±  s . e .; P  < 0·05). Minor differences were found in other elements of fibre composition, with the exception of a five‐fold greater lipid content in pectoral red fibres of P. borchgrevinki (0·074 ± 0·014 mean ±  s . e .) v . T. bernacchii (0·010 ± 0·003; P  < 0·05). Differences in muscle fine structure among species clearly reflected differences in their ecotype.     

Morphological and histochemical characterization of the pectoral fin muscle of batoids

Batoids differ from other elasmobranch fishes in that they possess dorsoventrally flattened bodies with enlarged muscled pectoral fins. Most batoids also swim using either of two modes of locomotion: undulation or oscillation of the pectoral fins. In other elasmobranchs (e.g., sharks), the main locomotory muscle is located in the axial myotome; in contrast, the main locomotory muscle in batoids is found in the enlarged pectoral fins. The pectoral fin muscles of sharks have a simple structure, confined to the base of the fin; however, little to no data are available on the more complex musculature within the pectoral fins of batoids. Understanding the types of fibers and their arrangement within the pectoral fins may elucidate how batoid fishes are able to utilize such unique swimming modes. In the present study, histochemical methods including succinate dehydrogenase (SDH) and immunofluoresence were used to determine the different fiber types comprising these muscles in three batoid species: Atlantic stingray (Dasyatis sabina), ocellate river stingray (Potamotrygon motoro) and cownose ray (Rhinoptera bonasus). All three species had muscles comprised of two muscle fiber types (slow-red and fast-white). The undulatory species, D. sabina and P. motoro, had a larger proportion of fast-white muscle fibers compared to the oscillatory species, R. bonasus. The muscle fiber sizes were similar between each species, though generally smaller compared to the axial musculature in other elasmobranch fishes. These results suggest that batoid locomotion can be distinguished using muscle fiber type proportions. Undulatory species are more benthic with fast-white fibers allowing them to contract their muscles quickly, as a possible means of escape from potential predators. Oscillatory species are pelagic and are known to migrate long distances with muscles using slow-red fibers to aid in sustained swimming.     

Mode of locomotion places selective pressures on Antarctic and temperate labriform swimming fish

The physiological responses to exercise and stress of the Antarctic labriform swimmer Pagothenia borchgrevinki were compared to the temperate labriform swimmers Notolabrus celidotus and Notolabrus fucicola. Basic swimming characteristics were very similar amongst the three species with P. borchgrevinki showing a reduced capacity for exercise. P. borchgrevinki showed large increases in haematocrit (Hct) following exercise that were not seen in the temperate species. Lactate dehydrogenase (LDH) activities were high in the white myotomal muscle from the Antarctic fish, with a distinct indication of metabolic cold adaptation in this enzyme. Nevertheless, although the temperate fish showed elevated muscle lactate concentrations following either exercise or electrical stimulation the Antarctic fish did not. The data suggest that poor anaerobic performance of white muscle is associated with the labriform mode of locomotion.     

Histochemical characterization of myotomal muscle in the roach, Rutilus rutilus (L.)

A histochemical study of the myotomal muscles in the roach revealed three main muscle regions: red, intermediate and white. These were distinguished on the basis of glycogen content, succinate dehydrogenase (SDH), and myofibrillar ATPase (mATPase) activity. Except for the red fibre region, none of these described regions is homogeneous. The principal new findings are the toniclike fibre, the presence of a transitional zone with two fibre types, and the mosaic organization of the white fibre region. The significance of this type of myotome architecture in relation to the locomotion of the species is discussed.     

The effect of starvation on the ultrastructure of the red and white myotomal muscles of the crucian carp (Carassius carassius)

Summary The effect of 16 weeks total starvation on the ultrastructure of the red and white myotomal muscles of the crucian carp (Carassius Carassius) has been investigated. In the white fibres the amount of myofibrillar material fell from 89.6% to 70.7% of the total fibre volume whilst in the red fibres the fall was from 72.2% to 70.3%. The sarcoplasmic reticulum appeared to have become swollen during starvation in both fibre types. In the white fibres the terminal cisternae of some triads seem to have fused. The volume of the red fibres occupied by mitochondria was reduced from 16.2 % to 5.9 %. The concentration of mitochondria in the white fibres was too low to detect any quantitative changes. A marked reduction in the amount of euchromatin material was observed in most white fibre nuclei and many red fibre nuclei. Many of the ultrastructural changes noted in the present study can be correlated with biochemical changes known to occur in the red and white myotomal muscles of fish during starvation. This work was supported by a grant from the Natural Environmental Research Council.     

Growth dynamics of caudal and pectoral fin muscle fibres in a carangid, Caranx malabaricus (Cuv. & Val.), and their possible relation with somatic growth

The growth dynamics of red, pink and white fibres of the caudal and pectoral fin muscles are described in Carans malabaricus (Cuv. & Val.) in relation to their somatic growth. In all three fibre types growth occurred by an increase in fibre number and diameter in small size classes of fish and by an increase in diameter only in larger fish. The growth dynamics of the three fibre types were similar to those of the myotomal muscle fibres and paralleled the somatic growth pattern of this fish.     

Histochemical characterization of myotomal muscle of five teleost species

A histochemical study was performed on the myotomal musculature of five teleost fish from four families (longnose dace, Rhinichthyes cataractae ; bluegill, Lepomis macrochirus , smallmouth bass, Micropterus dolomieul ; yellow perch, Perca flavescens ; lake whitefish, Coregonus clupeaformis ). Three main types of fibre (red, pink, white) were distinguished in these species on the basis of relative activities of actomyosin adenosine triphosphatase (ATPase) and NADH diaphorase. White muscle formed the bulk of the myotomal musculature. The proportion of red muscle was greater in the caudal region (11·–5% of the total cross-sectional area) than in more anterior regions of the body in all the species. Pink fibres comprised only a transitional layer (cells deep) between red and white. In bluegill, the red fibres penetrated deeper medially from the superficial lateral position than in the other four species.
It appears that, among the present five species, the somewhat greater amount of red muscle in yellow perch may be related to the free-cruising sometimes associated with that species, compared to the more desultory activity of the other four. It is noted that the amount of red muscle relative to white is appreciably greater in all five species than that revealed in two esocid species in an earlier study; the latter are' ambush predators'that swim very rapidly towards prey.     

Energy metabolism of carp swimming muscles

Summary Electromyography has been used to study the recruitment of red, pink and white muscle fibres of the Mirror carp at different swimming speeds. Locomotion below 0.3–0.5 L/S (lengths per second) is achieved primarily by fin movements after which the red myotomal muscle becomes active. Pink muscle fibres are the next type to be recruited at speeds around 1.1–1.5 L/S. White muscle is only used for fast cruising in excess of 2–2.5 L/S and during bursts of acceleration.Studies of the myofibrillar ATPase activities of these muscles have shown a ratio of 124 for the red, pink and white fibres respectively. The myosin low molecular weight components, which are characteristic of the myosin phenotype, have been investigated by SDS polyacrylamide electrophoresis. The light chain patterns of the pink and white muscles were identical and characteristic of the fast myosin phenotype. Red muscle myosin had a light chain pattern characteristic of slow muscles. It would appear that there is a relationship between the speed of contraction of the fibre types and the locomotory speed at which they are recruited.The activities of some enzymes of energy metabolism have also been determined in the three muscle types. Enzymes associated with oxidate metabolism have high, intermediate and low activities in the red, pink and white muscles respectively. Pyruvate kinase and lactate dehydrogenase activities were considerably higher in the pink than in either red or white muscles. It is suggested that the high capacity for anaerobic glycolysis of the pink muscle is associated with its recruitment for sustained effort at swimming speeds above which the fish can no longer meet all its energy requirements by gas exchange at the gills.Abbreviations used EDTA ethylenediamine tetraacetic acid - L/S lengths, sec^–1 - LDH Lactate dehydrogenase - PFK phosphofructokinase - SDS sodium dodecyl sulphate - TCA trichloroacetic acid     

Histochemical characterization of myotomal muscle in the bluntnose minnow, Pimephales notatus Rafinesque

A histochemical study of the axial muscles in the bluntnose minnow, Pimephales notatus Rafinesque, revealed three main types of fibres-red, white and pink. These were distin- guished on the basis of glycogen or lipid contents, or of NADH diaphorase and actomyosin ATPase activities. White muscle formed the largest fraction of the total, whereas red ranged from slightly > 1% of the total cross-sectional area in the immediately post-pectoral fin region to slightly <4% in the post-anal region. Pink muscle formed only a few layers of fibres between red and white. Results are discussed in relation to possible division of labour among the different types of fibres. However, it is emphasized that fibre types may be more functionally versatile in fish muscles than has frequently been supposed.     

The fine structure of the fin musculature in two teleost species with different swimming modes,the puffer,Tetraodon steindachneri,and the goldfish,Carassius auratus

Summary Puffer fish (Tetraodon steindachneri) can execute precise maneuvers due to their highly specialized mode of propulsion. In the conventional locomotion exemplified by the goldfish (Carassius auratus), the fish thrusts are generated by lateral beating of the caudal fin. In contrast, the puffer generates its propulsive force by very rapid undulating movements of the pectoral, dorsal and anal fins. The fine structure of the fin muscles is identical in the two species of fishes, despite the differences in fin movement; cytologically, the fibers are intermediate between those of red and of white muscle. On the other hand, both the fusion frequency and the number of motor endplates are considerably higher in the fin muscles of the puffer than in those of the goldfish.     

Pectoral fin beat frequency predicts oxygen consumption during spontaneous activity in a labriform swimming fish (Embiotoca lateralis)

The objective of this study was to identify kinematic variables correlated with oxygen consumption during spontaneous labriform swimming. Kinematic variables (swimming speed, change of speed, turning angle, turning rate, turning radius and pectoral fin beat frequency) and oxygen consumption (MO₂) of spontaneous swimming in Embiotoca lateralis were measured in a circular arena using video tracking and respirometry, respectively. The main variable influencing MO₂ was pectoral fin beat frequency (r ² = 0.71). No significant relationship was found between swimming speed and pectoral fin beat frequency. Complementary to other methods within biotelemetry such as EMG it is suggested that such correlations of pectoral fin beat frequency may be used to measure the energy requirements of labriform swimming fish such as E. lateralis in the field, but need to be taken with great caution since movement and oxygen consumption patterns are likely to be quite different in field situation compared to a small lab tank. In addition, our methods could be useful to measure metabolic costs of growth and development, or bioassays for possible toxicological effects on fish.     

Source of electron energy for animal metabolism

Summary The histochemical localization of ascorbic acid was carried out in the pectoral muscles of various birds using a modified method. — The greater deposition of silver granules within the red fibres as well as in their nuclei than in those of the white ones is correlated with higher metabolic activity of the former. — The possible role of ascorbic acid as a participant in energy transfer mechanisms in the muscle fibres; in lipid synthesis and the importance of AA and its free radical in protein metabolism are discussed.     

AMP-deaminase in elasmobranch fish: a comparative histochemical and enzymatic study

AMP-deaminase activity was measured in white muscle from a wide range of fish, including one cyclostome, 13 chondrosteans, and one teleost to elucidate the pattern of the AMP-deaminase activity in white muscle of fish. Compared to a mammalian (rat) muscle extract, low enzyme activities are found in the cyclostome and two elasmobranchs from two families (Scyliorhinidae, Hexanchidae). In contrast, higher AMP-deaminase activities, similar to mammals, are expressed in Squalidae, all families of skates, Chimaeridae and in the teleostean fish. We then compared AMP-deaminase activities in red and white muscles from two representative elasmobranch fish, the dogfish (Scyliorhinus canicula) and the thornback ray (Raja clavata). The fibre type composition and distribution of the locomotory musculature were determined in these two elasmobranchs to establish a relationship between the morphology, the type of fibres of the locomotion-implicated muscles and the AMP-deaminase activity. Experimental data are discussed with respect to the layout of fibres in the myotome. In both species, three fibre types were identified. In the two fish myotomes, most of the axial muscles are white fibres while red fibres constitute a thin sheet. Some differences were observed between the two species in the distribution of intermediate fibres: in dogfish, these are located between the red and white fibres; in thornback ray, some are dispersed within the white fibre region, while others form an intermediary layer like in dogfish. These results suggest that in the course of evolution, an amplification of the AMP-deaminase activity in muscle was coupled with increase of complexity of the muscular structure.     

Myosin light chain patterns of individual fast and slow-twitch fibres of rabbit muscles

Summary Single muscle fibres were isolated by microdissection from freeze-dried samples of rabbit psoas and soleus muscles. The individual fibres were typed according to qualitative histochemical reactions for succinate dehydrogenase or NADH-tetrazolium reductase and for alkaline Ca²⁺-activated myofibrillar myosin ATPase after acid or alkaline preincubation. Methods are described for electrophoretic analysis by means of polyacrylamide disc electrophoresis in the presence of SDS of total myofibrillar proteins in single fibres after pre-extraction of soluble proteins. Fast-twitch white fibres revealed a myosin light chain pattern characteristic of fast-type myosin with three light chains of apparent molecular weights of 22,300 (LC₁), 18,400 (LC₂) and 16,000 (LC₃). Fast-twitch red fibres were indistinguishable in this respect from fast-twitch white fibres and showed an identical pattern of myosin light chains. Slow-twitch fibres could be characterized by a myosin light chain pattern typical of myosin of slow-twitch muscles with peptides of the apparent molecular weights of 23,500 (LC_1Sa), 23,000 (LC_1Sb) and 18,500 (LS_2S). Slow-twitch fibres isolated from soleus as well as from psoas muscle were indistinguishable with regard to their myosin light chain patterns, thus suggesting that fibres of the same histochemical type correspond in their myosin light chain patterns irrespective of their origin from different muscles.Dedicated to the memory of Ernest Gutmann who has contributed so much to our knowledge on differentiation of muscle and who died on August 6, 1977     

Maximal activities of hexokinase, 6-phosphofructokinase,oxoglutarate dehydrogenase,and carnitine palmitoyltransferase in rat and avian muscles

The maximum activities of 6-phosphofructokinase and oxoglutarate dehydrogenase in muscle provide quantitative indices of the maximum capacities of anaerobic glycolysis and the Krebs cycle (i.e. the aerobic capacity) respectively. These activities were measured in red, white, and cardiac muscle of birds and the rat. The activities in the white pectoral muscle of the domestic fowl suggest that the Krebs cycle plus electron transfer could provide only about 1% of the rate of ATP production provided by anaerobic glycolysis whereas in pigeon pectoral muscle the predicted maximal rates from the two processes are similar. In contrast to domestic-fowl pectoral muscle, the white rat muscle, epitrochlearis, contains a significant activity of oxoglutarate dehydrogenase, which indicates that the Krebs cycle could provide about 12% of the maximum rate of ATP formation. This may be explained by a higher proportion of type-I and -IIA fibres in the rat muscle compared to the avian muscle. In the aerobic muscles of the rat the maximum activities of carnitine palmitoyl transferase indicate that fatty-acid oxidation could provide a high rate of ATP formation.     

Thermal dependence of contractile properties of single skinned muscle fibres from Antarctic and various warm water marine fishes including Skipjack Tuna (Katsuwonus pelamis) and Kawakawa (Euthynnus affinis)

Summary Single fast fibres and small bundles of slow fibres were isolated from the trunk muscles of an Antarctic (Notothenia neglecta) and various warm water marine fishes (Blue Crevally,Carangus melampygus; Grey Mullet,Mugil cephalus; Dolphin Fish,Coryphaena hippurus; Skipjack-tuna,Katsuwonus pelamis and Kawakawa,Euthynuus affinis). Fibres were chemically skinned with the nonionic detergent Brij 58.For warm water species, maximum Ca²⁺-activated tension (P ₀) almost doubled between 5–20°C with little further increase up to 30°C. However, when measured at their normal body temperatures,P ₀ values for fast fibres were similar for all species examined, 15.7–22.5 N · cm^–2. Ca²⁺-regulation of contraction was disrupted at temperatures above 15°C in the Antarctic species, but was maintained at up to 30°C for warm water fish.Unloaded (maximum) contraction speeds (V _max) of fibres were determined by the slacktest method. In general,V _max was approximately two times higher in white than red muscles for all species studied, except Skipjack tuna. For Skipjack tuna,V _max of superficial red and white fibres was similar (15.7 muscle lengths · s^–1 (L ₀ · s^–1)) but were 6.5 times faster than theV _max of internal red muscle fibres (2.4±0.2L ₀ · s^–1) (25°C). V _max forN. neglecta fast fibres at 0–5°C (2–3L ₀ · s^–1) were similar to that of warm water species measured at 10–20°C. However, when measured at their normal muscle temperatures, theV _max for the fast muscle fibres of the warm water species were 2–3 times higher than that forN. neglecta.In general,Q _{10(15–30°C)} values forV _max were in the range 1.8–2.0 for all warm water species studied except Skipjack tuna.V _max for the internal red muscle fibres of Skipjack tuna were much more temperature dependent (Q _{10(15–30°C)}=3.1) (P<0.01) than for superficial red or white muscle fibres. The proportion of slower red muscle fibres in tuna (28% for 1 kg Skipjack) is 3–10 times higher than for most teleosts and is related to the tuna's need to sustain high cruising speeds. We suggest that the 8–10°C temperature gradient that can exist in Skipjack tuna between internal red and white muscles allows both fibre types to contract at the same speed. Therefore, in tuna, both red and white muscle may contribute to power generation during high speed swimming.