Muscle cellularity, enzyme activities, and nucleic acid content in meagre (Argyrosomus regius)

Abstract

Anatomical and biochemical indices of axial muscle growth were monitored in farmed meagre (Argyrosomus regius (Asso, 1801)), a species with larger ultimate size. Within the first 19 months of a production cycle, body mass exceeded 1300 g. The specific daily growth rate ranged from a winter low of 0.2% to a summer high of 1.3%. Axial muscle RNA:DNA ratio decreased and cytochrome c oxidase levels increased from spring to winter, indicating a metabolic reorganisation of this tissue in response to winter temperature lows. Body mass correlated positively with increased lactate dehydrogenase activity and myofibre size (hypertrophy). The DNA:protein ratio, the myofibre density, and the percentage of small myofibres (0-150 µm 2 ) decreased towards the end of the production cycle. However, small myofibres persisted even after the first 20 months of rearing. Compared with commonly cultivated species in the Mediterranean region, meagre exhibits delayed onset of puberty, larger ultimate size, and growth rate that is supported by the recruitment of new muscle fibres. This is in agreement with the hypothesis of a relationship between ultimate size and muscle growth dynamics.Résumé : Des indices anatomiques et biochimiques de croissance des muscles axiaux ont été mesurés dans le temps chez le maigre (Argyrosomus regius (Asso, 1801)) d'élevage, une espèce d'assez grande taille ultime. Dix-neuf mois après le début du cycle de production, la masse corporelle dépassait 1300 g. Le taux de croissance spécifique quotidien oscillait entre un minimum hivernal de 0,2 % et un maximum estival de 1,3 %. Le rapport ARN:ADN des muscles axiaux a diminué alors que les teneurs en cytochrome oxydase c ont augmenté du printemps à l'hiver, témoignant d'une réorganisation métabolique de ces tissus en réponse aux faibles températures hivernales. La masse corporelle était corrélée positivement à l'augmentation de l'activité de la lacticodéshydrogénase et de la taille des myofibres (hypertrophie). Le rapport ADN:protéines, la densité de myofibres et le pourcentage de petites myofibres (0-150 µm 2 ) ont diminué vers la fin du cycle de production. Toutefois, des myofibres de petite taille demeuraient même après les 20 premiers mois d'élevage. Comparativement aux espèces couramment cultivées dans la région méditerranéenne, le maigre présente un début de puberté tardif et une taille ultime et un taux de croissance plus importants, favorisés par le recrutement de nouvelles fibres musculaires. Ces constatations concordent avec l'hypothèse voulant qu'il y ait un lien entre la taille ultime et la dynamique de la croissance musculaire.

Growth performance and product quality of meagre (Argyrosomus regius) fed diets of different protein/lipid levels at industrial scale

“…Long-term trials conducted in larger fish reaching commercial sizes, are limited to comparisons of meagre that received variable commercial diets (Mittakos et al 2012;Vargas-Chacoff et al 2014) while growth results are also missing (Piccolo et al 2008). Substitution of fishmeal and fish oil by vegetable raw materials and its impact on meagre growthfeed utilisation, metabolism, digestion and fatty acids profile has also been a subject of research (Emre et al 2015;Ribeiro et al 2015).…”

The Influence of Diet Containing Wheat Gluten Supplemented with Dipeptides or Amino Acids on the Morphology of White Muscle of Yellow Perch (Perca flavescens)

“…Histomorphometric measurements were conducted on the upper right quarter of the cross-section at the level of the anal opening (five sections per fish) and included: white muscles area (CSAw), the total number of muscle fibers (TFN), the total number of white muscle nuclei (TNN), muscle fiber area (FA), and number of the PCNA-positive myonuclei on the epaxial quarter of white muscle. Moreover, to estimate hypertrophy and hyperplasia processes, the following parameters were calculated: TFN/CSAw-index of muscle hypertrophy, TNN/TFN-index of number of muscle fiber nuclei, PCNA/TNN-index of proliferation nuclei [23,24].…”

Metabolic differentiation of diploid and triploid European sea bass juveniles

“…The DNA and RNA contents of axial muscle tissue were estimated according to the method of Burness et al (1999) with some modifications as described by Mittakos et al (2012). Sample of white epaxial muscle was obtained and DNA was extracted using the phenol-chloroform extraction procedure.…”

“…Activity of the glycolytic enzyme lactate dehydrogenase (LDH, EC 1.9.3.1) was assayed in a medium of 50 mM potassium phosphate buffer (pH 7.0) containing 0.15 mM NADH and 0.60 mM sodium pyruvate (Mittakos et al 2012).…”

“…The total DNA of a tissue can reflect the number of cells, but is expected to be higher in triploids (Cimino 1974). RNA content may vary according to cell size and tissue growth (Goolish et al 1984;Mittakos et al 2012) and can be used as an index of somatic growth rate in diploid and triploid fish (Arndt et al 1994;Suresh and Sheehan 1998). The ratio of RNA/DNA and protein/ DNA can provide some information for the nutritional status and the protein metabolism of growing fish, but these ratios should be used with caution due to the increased DNA content of 3n fish (Suresh and Sheehan 1998).…”