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.     

Regional variations in fibre growth dynamics of myotomal and caudal fin muscles in relation to body size of a freshwater teleost, Barbus sarana (Cuv. & Val.)

The growth of red fibres in anterior and middle myotomal regions of B. sarana was mainly by hyperplasia in smaller size classes. In higher size classes, growth by hyperplasia was greater in posterior myotomal region compared to the other two myotomal regions. The growth of pink fibres in anterior myotomal regions was mainly by hypertrophy. The middle and posterior myotomal regions showed fibre growth by hyperplasia. The growth dynamics of white fibres revealed more or less similar pattern in all three myotomal regions against the somatic development. White fibres grew by hyperplasia up to 8 cm F.L. size classes and thereafter by hypertrophy. However, in > 12 cm F.L. size classes, the mean diameter of white fibres did not increase significantly. Similar pattern of growth was found in the white fibres of caudal fin muscle. It is interesting to note that the hyperplasia was mostly completed in the white fibres of the smallest fish studies, whereas, it continued to quite larger fish size in red and pink fibres. Thus, hyperplasia and hypertrophy may be responsible for growth in all fibre types in all myotomal regions in relation to somatic development in this small and medium growing species.     

Growth dynamics of white myotomal muscle fibres in the bluntnose minnow, Pimephales notatus Rafinesque, and comparison with rainbow trout, Salmo gairdneri Richardson

The dynamics of increase of the predominant white muscle fibres of the myotomal bulk in bluntnose minnow, Pimephales notatus , ranging from 2.0 to 9.1 cm f.l. have been analysed by examination of modal progression of fibre diameter frequency classes in fish fed to satiation and growing at different rates at 15, 25 or 30°C. Recruitment of new fibres appeared to contribute little to increase in muscle bulk above 4 cm f.l. , and nothing beyond 6 cm. The dominant means of increase was increase in fibre diameter. The limiting fibre diameter seemed to be 120 μ. These dynamics, which result in an approximately 1: 1 ratio between mean fibre diameter and f.l. , are in contrast to those of the myotomal white muscle of rainbow trout, Salmo gairdneri , in which, regardless of differences in somatic growth produced by temperature, ration size or growth hormone administration, mean fibre diameter does not exceed that in bluntnose minnow until trout exceed 30 cm f.l. In trout there is, moreover, input of new fibres up to approximately 50 cm f.l. , when subsequent growth, as in the minnow, is by means of fibre diameter increase. The bluntnose minnow is a small, slow growing species; the rainbow trout is a large, fast growing species. The discussion links these facts with the observed differences in fibre growth dynamics in relation to a hypothesis of interspecific differences in fish growth capability.     

Hyperplasia and hypertrophy in the growth of skeletal muscle in juvenile Atlantic salmon, Salmo salar L.

Both red and white muscle fibre numbers in juvenile Atlantic salmon increased gradually with fish length throughout the freshwater growth period. Mean fibre area increased as fish grew to 6.5 cm f.l. , but thereafter was unrelated to fish length. Hyperplasia was most obvious when fish were growing fastest, and was the dominant growth process in fish over 6.5 cm f.l. Hypertrophy was most important when growth was slow, as in autumn and winter.
Mean white fibre area was significantly smaller in deep muscle than at medial and superficial sites. Total cross-sectional area of red, white and total trunk muscle increased with fish length. The ratio of red: white cross-sectional area increased with fish length to a plateau at about 10% after 6.5 cm f.l.     

Growth dynamics of white and red muscle fibres in fast- and slow-growing strains of rainbow trout

Compared with fish of a slow-growing strain, fast-growing rainbow trout exhibited significantly smaller white fibre diameters, throughout development from hatching to 24 cm body length, although possessing similar total number of fibres. In contrast, in red muscle, no differences were observed in fibre diameter between the two strains, but the fast growing fish showed a significantly higher number of red fibres. The differences in growth rate between the two strains were related to the mean white fibre diameter and were found to be matched by proportional adjustments in recruitment of new fibres to the growing muscle. Thus, the largest and fastestgrowing strain showed evidence of sustained higher recruitment of muscle fibres that endowed this strain with the potential to maintain rapid somatic growth for longer and accomplish greater muscle growth.     

Numbers of muscle nuclei and myosatellite cell nuclei in red and white axial muscle during growth of the carp (Cyprinus carpio)

We determined the percentages of muscle fibie nuclei and satellite nuclei over a growth range of carp ( Cyprinus carpio ), as the increase in the number of muscle fibre nuclei is an important aspect of the increase in muscle mass, and myosatellite cells are believed to be the source of new muscle fibre nuclei. In white as well as in red axial muscle the percentage of the nuclei present in muscle that are muscle nuclei (muscle fibre nuclei+myosatellite nuclei) remained constant during growth (54 and 32% respectively). The difference in the percentage of non-muscle nuclei between white and red axial muscle is mainly caused by the higher content of endothelial nuclei in red axial muscle.
In white axial muscle the DNA/protein ratio (nucleus/sarcoplasm ratio) decreased between 3 and 15 cm S.l. In red axial muscle we found a continuous decrease in DNA/protein ratio over the entire investigated size range (3–50 cm s.l.). This may be related to a longer occurrence of hyperplasia in red than in white axial muscle.
In both fibre types the percentage of muscle nuclei being myosatellite nuclei decreased with increasing length, In white axial muscle it decreased from about 5% in carp of 5 cm s.l. to less than 1% in carp of 20 cm S.L.; for red muscle these values were 11 and 3% respectively.
For white axial muscle we calculated that, especially in larger fish, the myosatellite ceils alone cannot account for the increase in the number of muscle fibre nuclei during growth. The percentage of proliferating nuclei in muscle tissue, measured by the uptake of 5-bromo-2'-deoxy-uridine, is high enough to account for the total increase in nuclei. So indirect evidence is available that another cell type present in the muscle tissue may also be involved in the formation of additional muscle fibre nuclei.     

The relationship between mosaic muscle fibres and size in rainbow trout (Salmo gairdneri)

The dynamics of increase of the mosaic muscle in hatchery reared rainbow trout (2·3 to 61·3 cm fork length) are investigated. In trout <5 cm, all fibres are <40 μm in diameter; from 5 to 20 cm the diameter mode remains in the 0–39·9 μm class and there is some extension in range of diameter, thereby suggesting that mosaic muscle increase up to 20 cm is mainly by recruitment of new (small) fibres. When trout exceed 20 cm, mode of fibre diameter shifts to the 40–79·9 um class and fibres of larger diameter (> 100 μrn) appear but the subsequent overall fibre diameter frequency distribution changes little until 50 cm. Increase in muscle during the phase 20–50 cm seems partly attributable to increase in fibre diameter, but remains largely the result of recruitment of small fibres, although the mechanism of the latter process appears less clear than in fish of <20 cm. The recruitment of new fibres stops at 55 cm and further increase in mosaic muscle evidently depends upon the ability of existing fibres to increase in diameter. Possible means by which increasing muscle fibre diameter may limit the ultimate size which trout may achieve are discussed. A phenomenon of apparent reduction in fibre diameter in winter among fish 20–39·9 cm long is noted and its significance is considered.     

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.     

Differences in protein mobilization between ventral and dorsal parts of white epaxial muscle from fed, fasted and refed white sturgeon (Acipenser transmontanus)

The effect of starvation-refeeding on protein mobilization in the lateral line, lateral (midway between lateral line and dorsum) and dorsal parts of white sturgeon ( Acipenser transmonlanus ) white epaxial muscle (type IIB) were compared by measuring muscle cross-sectional fibre areas. Effects on red (type I) and pink (type IIA) muscle were also studied. Fish starved throughout the experiment (5 weeks) showed a uniform response, i.e. the cross-sectional fibre area decreased at all sampled locations in the white muscle as well as in red and pink muscle. Fibre size in fish refed for 3 weeks after 2 weeks of fasting (S/F) was reduced mainly in the dorsal region of the white muscle. Starvation for 3 weeks after 2 weeks of initial feeding (F/S) also reduced fibre size mainly in the dorsal regions of the white muscle and in the pink muscle. The results indicate that in sturgeon exposed to short periods of low food availability, protein is utilized preferentially from trie more dorsal regions of the white epaxial muscle and from pink muscle. Protein in white muscle located closer to the lateral line and in red muscle seems to be spared. With the onset of refeeding, protein deposition occurred rapidly in pink muscle, but was delayed significantly in the dorsal part of the white muscle.     

Histochemical fibre types in the lateral muscle of fishes in fresh, brackish and salt water

The histochemical pattern of red, pink and white muscle of fish living in fresh, brackish, and salt water is reported. The muscle fibres were stained routinely during the year for lactate dehydrogenase (LDH), menadione α-glycerophosphate dehydrogenase (Mα—GPDH), succinic dehydrogenase (SDH), myosin adenosine triphosphatase (myosin ATPase), phosphorylase, lipids and glycogen. The pink and red muscles contain more glycogen and lipids and have a higher SDH activity, which is in accord with their aerobic metabolism and function in sustained swimming activity. The acid labile myosin ATPase activity characteristic of fast twitch fibres is present in the white fibres of most species, however in the white muscle of Gobius paganellus the enzyme activity is stable to both acid and alkali and, in addition, there is a scattered distribution of different fibre types in red and, especially, pink muscle. A study of seasonal variation patterns of myosin ATPase in white muscle of mugilidae over a period of two years has demonstrated, in late summer, the appearance of new small diameter fibres, with a high acid stable enzyme activity, that develop into the large diameter acid labile fibres.     

Temperature acclimation in crucian carp, Carassius carassius L., morphometric analyses of muscle fibre ultrastructure

Carp show a partial compensation in metabolic rate and activity following temperature acclimation. In the present study crucian carp, Carassius carassius , were acclimated for eight weeks to either 2deg; C or 28deg; C. The effects of temperature acclimation on muscle fibre ultrastructure has been investigated. The fractional volume (%) of each fibre type occupied by mitochondria and myofibrils was determined using a point counting morphometric method. Mitochondrial density was found to be higher in the muscles of cold (red fibres 25%; pink fibres 20% and white fibres 4%) than in those of warm acclimated fish (red fibres 14%, pink fibres 11%, white fibres 1%). The proportion of subsarcolemmal to intra-myofibrillar mitochondria was significantly lower in the red fibres of cold acclimated fish. Metabolic compensation to low temperatures are therefore associated with an increase in the number of mitochondria per cell. In contrast, the fractional volume occupied by myofibrils actually decreased following cold acclimation. Evidence is reviewed that temperature compensation of contractile activity results from qualitative rather than quantitative changes in myofibrillar proteins.     

Growth and muscle cellularity of diploid and triploid Atlantic cod (Gadus morhua Linnaeus, 1758) larvae

The aim of this study was to compare somatic growth and muscle fibre development in diploid and triploid siblings of Atlantic cod (Gadus morhua Linnaeus, 1758) during the larval stage. Newly hatched larvae were transferred into 200‐L tanks, three tanks per ploidy group (70 larvae L^?1, continuous light, gradually increasing seawater temperature 7–11°C and flow rates 50–117 L h^?1). Larvae were fed rotifers from 2 to 22 days post hatch (dph), Artemia 19–31 dph and weaned onto a microparticulate diet from 26 dph until the end of the experiment. Measurements of growth (dry weight, standard length) and muscle cellullarity were taken at intervals between 1 and 44 dph. Ploidy groups showed a similar performance throughout the trial, although a marked stagnation in growth was observed for triploids during the weaning from Artemia onto dry feed. Overall, diploid and triploid cod larvae showed a similar development in muscle fibre growth pattern during the experimental period. For both groups, the total number of fast muscle fibres showed a 10‐fold increase (from 384 to 3462), whereas the diameter of fast fibre increased from 8.9 to 13.3 μm (mean number from all treatments). Thus, a temporary but significant effect of triploidy on fast muscle fibre growth pattern was observed in 19 dph larvae in terms of fibre size and number, with triploids showing larger mean fast fibre diameter (11.62 ± 0.63 vs. 10.05 ± 0.34) and a lower number of fibres with a diameter <5 μm than their diploid siblings. Thus, this was found to be related to larvae size and to the differences in total fast fibre cross sectional areas rather than to ploidy status. Overall, our results suggest possible deficiencies in nutrients’ digestion and absorption of triploid cod larvae particularly during the transitional period from live food to inert diets.     

Muscle growth in juvenile Atlantic salmon as influenced by temperature in the egg and yolk sac stages and diet protein level

Atlantic salmon Salmo salar eggs derived from a single family were incubated at two different water temperature regimes, with a mean temperature between fertilization and first feeding differing between 6 and 10° C (HT) and 2–6° C (LT). From first feed the fry were kept under the same rearing conditions and fed either high (50%) or low (45%) protein diet level of equivalent energy content until smoltification. All treatments were carried out in duplicate tanks. At first feeding the groups were similar in mass, but thereafter the HT‐fish were heavier and longer compared to the LT‐fish throughout the experiment. The groups fed the high protein diet were significantly heavier and longer compared with the corresponding low protein diet. A strong positive relationship was observed between L_F and total white muscle cross‐sectional area (CSA), white muscle fibre diameter and fibre number. There were also equivalent relationships with body mass. There were no significant differences in CSA, the mean diameter or the number of white muscle fibres per CSA between groups at first feed. Muscle fibre number and CSA increased in all groups during the experiment, whereas fibre diameter reached a plateau when the fish reached > 9 cm L_F. There were only minor effects of pre‐hatch and yolk sac stage temperature on CSA and fibre number per CSA during the juvenile stage. In short periods the LT‐group had larger CSA and higher fibre number than the HT‐groups, but this differences had disappeared by the end of the juvenile stage. No differences in mean fibre diameter were found between groups, except at the time of smoltification. When the fish approached smoltification a decrease in mean fibre diameter and an increase in muscle fibres <25 µm was seen and taken as an indication of recruitment of new fibres (hyperplasia). Only minor differences in CSA, fibre number or fibre diameter was observed between high and low protein diet groups.     

Explosive development of pectoral muscle fibres in large juvenile blue catfish Ictalurus furcatus

As part of an effort on scaling of pectoral spines and muscles, the basis for growth was examined in six pectoral muscles in juvenile blue catfish Ictalurus furcatus, the largest catfish in North America. Fibre number increases slowly in fish from 13·0 to 26·4 cm in total length, doubles by 27·0 cm and remains stable in larger individuals. Simultaneously, mean fibre diameter decreases by half, caused by the addition of new small fibres, before increasing non‐linearly in larger fish. The orders of magnitude disparity between the size at hatching and the size of large adults may have selected for rapid muscle fibre addition at a threshold size.     

The distribution of capillaries in the somatic musculature of two vertebrate types with particular reference to teleost fish

The distribution of capillaries in teleost and rat striated muscles was investigated using a number of different methods. A new method for directly viewing capillaries was developed. Teleost white muscle has a capillary: fibre (C:F) ratio of between 0.2 and 0.3; and 0.6 to 1.0 peripheral capillaries per muscle fibre. 26-49% of fibres had no peripheral capillaries. Values for the rat gastrocnemius were 1.2, 2.6 and 4.8% respectively which compares well with literature values. Flathead red muscle had a C:F ratio of between 1.9 and 2.5; and between 5.3 and 6.6 peripheral capillaries per muscle fibre depending on the method used. Values for rat soleus were 1.8 and 4.1 respectively. Teleost pink fibres had an intermediate number of capillaries. Rat striated muscle, particularly the gastrocnemius, was found to be heterogeneous with respect to the distribution of capillaries. Flathead red muscle was homogeneous whilst teleost white muscle was only slightly variable. Flathead red muscle fibres are well suppled with subsarcolemmal mitochondria. These show a clumped distribution corresponding to the position of capillaries. In contrast teleost white fibres are almost totally devoid of these and all other mitochondria. No differences were observed in the vascularisation of either muscle type along the length of the fish. The results are discussed in relation to the division of labour between fibre types during swimming.     

Hyperplastic and hypertrophic growth of lateral muscle in blackspot seabream Pagellus bogaraveo from hatching to juvenile

To understand better the growth mechanisms in the economically important fish Pagellus bogaraveo, in terms of muscle fibre hyperplasia v. hypertrophy, the lateral muscle of this fish was studied morphometrically from hatching to juvenile comparing rostral and caudal locations. Fish were sampled at 0, 5, 23, 40, 70, 100, 140 and 180 days. Fibre types were first identified by succinate dehydrogenase (SDH) and immunostaining with a polyclonal antibody against fish slow myosin (4–96). Morphometric variables were then measured in transverse body sections, at both post‐opercular and post‐anal locations, to estimate the following variables: total muscle area [A (muscle)], total fibre number [N (fibres)], fibre number per unit area of muscle [N_A(fibres, muscle)] and cross‐sectional fibre area [ (fibres)] of the two main muscle fibre types (white and red). Overall, growth throughout the various stages resulted from increases both in the number and in the size of muscle fibres, paralleled by an expansion of the [A (muscle)]. Nonetheless, that increase was not significant between 0–5 days on one hand and 100–140 days, on the other hand. On the contrary, the [N_A(fibres, muscle)] declined as the body length increased. Analysis of the muscle growth kinetics suggested that, within the important time frame studied, hyperplasia gave the main relative contribution to the increase of white muscle [A (white muscle)], whereas red muscle [A (red muscle)] mainly grew by hypertrophy, with both phenomena occurring at a faster pace posteriorly in the body. Finally, when comparing rostral and caudal locations, a greater [N (fibres)] and [A (muscle)] of the posterior white and red fibres were the consistent features. It was also observed that the proportion of the cross‐sectional area of the myotomal muscle comprised of white muscle was greater in the anterior part of the fish.     

The lateral musculature of the common bully, Gobiomorphus cotidianus, a freshwater fish from New Zealand

A histochemical and ultrastructural study has shown that the myotome of the common bully, Gobiomorphus cotidianus , is composed of three muscle fibre types: white, pink and small diameter fibres. There are no red fibres. Both white and pink fibres have characteristics similar to these fibres found in other teleosts. The small diameter fibres are located in the position usually occupied by red fibres and are identified by their small size and poor staining characteristics. At the ultrastructural level these small fibres are seen to have few mitochondria and a poorly developed sarcoplasmic reticulum. It is suggested that the small diameter fibres are a type of tonic muscle used for positioning the trunk.     

Growth characteristics of skeletal muscle tissue in Oreochromis niloticus larvae fed on a lysine supplemented diet

The effect of lysine amino acid supplementation on the growth characteristics and morphological pattern of skeletal muscle tissue in Nile tilapia Oreochromis niloticus larvae was evaluated. There were four treatments (T) with increasing levels of lysine supplement (T1 = 0·0%; T2 = 1·1%; T3 = 1·7%; T4 = 4·0%) and one treatment with a commercial diet (T5). In all treatments, morphological and histochemical muscle tissue analyses were similar. Two distinct layers were identified: a superficial red layer, more developed in the lateral line region, formed by fibres with intense to moderate NADH‐TR reaction and strong acid‐stable mATPase activity, and a deep white one, most of the muscle mass, formed by fibres with weak NADH‐TR reaction and strong alkali‐stable mATPase activity. There was an intermediate layer between these two layers with fibres exhibiting either weak acid‐stable or acid‐labile mATPase activity. Body mass increase was significantly higher in T5 than in the lysine treatments (T1–T4). There was no difference in number and diameters of muscle fibres between lysine treatments. In T5, muscle fibre diameter and number were higher. The frequency of red fibres with diameters ≤8 μm was higher in the lysine treatments, and with diameters between 16 and 24 μm, was higher in T5. Most white fibre diameters in T5 were significantly larger than 24 μm and in T1–T4 were between 8 and 16 μm. Cell proliferation was higher in the lysine treatments and muscle growth in T5 was mainly by fibre hypertrophy.     

Red muscle fibre and capillary dimensions in different sizes of a tilapia, Oreochromis niloticus (Trewavas)

Measurements of muscle dimensions that affect respiration in relation to body weight were carried out in a tilapia, Oreochromis niloticus . The fish used in all measurements weighed 0.65–812.3 g. The data were analysed with respect to body weight using logarithmic transformations (log Y=log a + b log W ).
The slopes (b) of the log/log regression lines for weight of body trunk red muscle, average cross-sectional area of muscle fibre, average number of capillaries in direct contact with a muscle fibre, average capillary contact length with a fibre as a fraction of average fibre circumference and number of capillaries mm² of fibre cross-sectional area [N_A(cƒ)] were 1.16, 0.221, 0.084, 0.015, and −0.137 respectively.
These results show that there is an increase in muscle cross-sectional fibre area and number of capillaries in contact with muscle fibres whereas number of capillaries supplying a unit area of muscle fibre decreases during development. There is development of new capillaries with increase in cross-sectional area of red muscle fibres.     

Influence of bovine growth hormone on the growth dynamics of mosaic muscle in relation to somatic growth of rainbow trout, Salmo gairdneri Richardson

Bovine growth hormone (bGH), administered intramuscularly at 20 μg^-1 every 2 weeks, produced faster somatic growth in rainbow trout fingerlings to approximately 30 cm than in those not receiving the hormone. Both groups were maintained at 12° C, with a photoperiod of 16 : 8 LD, and on ad libitum rations daily. The faster growth was characterized by a controlled increase in input of fibres into the mosaic muscle (which dominates the body tissues by its bulk). It is not known if the enhanced input of fibres is an example of the known ability of the mosaic fibre mass to respond with flexibility and precision to widely differing somatic growth rates, or is a specific consequence of the growth hormone. In other fingerling trout receiving 4-5% daily rations and consequently growing slowly, bGH did not stimulate growth or evidently modify fibre input dynamics. Body dry weight, and condition ( K ), though modified by rations and growth rate, evidently had little effect on muscle fibre growth.