Transient up- and down-regulation of expression of myosin light chain 2 and myostatin mRNA mark the changes from stratified hyperplasia to muscle fiber hypertrophy in larvae of gilthead sea bream (Sparus aurata L.)

Hyperplasia and hypertrophy are the two mechanisms by which muscle develops and grows. We study these two mechanisms, during the early development of white muscle in Sparus aurata, by means of histology and the expression of structural and regulatory genes. A clear stage of stratified hyperplasia was identified early in the development of gilthead sea bream but ceased by 35 dph when hypertrophy took over. Mosaic recruitment of new white fibers began as soon as 60 dph. The genes mlc2a and mlc2b were expressed at various levels during the main phases of hyperplasia and hypertrophy. The genes myog and mlc2a were significantly up-regulated during the intensive stratified formation of new fibers and their expression was significantly correlated. Expression of mstn1 and igf1 increased at 35 dph, appeared to regulate the hyperplasia-to-hypertrophy transition, and may have stimulated the expression of mlc2a, mlc2b and col1a1 at the onset of mosaic hyperplasia. The up-regulation of mstn1 at transitional phases in muscle development indicates a dual regulatory role of myostatin in fish larval muscle growth

An opinion paper: emphasis on white muscle development and growth to improve farmed fish flesh quality

Due to rapid depletion of wild stocks, the necessity to cultivate fish is eminent. Current fish farming practices seek to improve flesh quality. The notion that white muscles are the main target of the fishing industry is emphasized. A novel approach is suggested based on the development of white muscles in wild fish from eggs to adults. A compilation of facts about white muscle structure, function and ontogeny is followed by an account of the changes in swimming behaviour and performance related to the use of white muscle during growth from larva to adult. Ecological data narrate early swimming performance with white muscle development and growth, unveiling some of the important natural selection factors eliminating weak swimmers and poor growers from the breeding stock. A comparison between fish culture practise and natural conditions reveals fundamental differences. New approaches following wild breeding processes promise several important advantages regarding the quality of white muscle

Characterisation and expression of calpain family members in relation to nutritional status, diet composition and flesh texture in gilthead sea bream (Sparus aurata).

Calpains are non-lysosomal calcium-activated neutral proteases involved in a wide range of cellular processes including muscle proteolysis linked to post-mortem flesh softening. The aims of this study were (a) to characterise several members of the calpain system in gilthead sea bream and (b) to examine their expression in relation to nutritional status and muscle tenderisation. We identified the complete open reading frame of gilthead sea bream calpains1-3, sacapn1, sacapn2, sacapn3, and two paralogs of the calpain small subunit1, sacapns1a and sacapns1b. Proteins showed 63-90% sequence identity compared with sequences from mammals and other teleost fishes, and the characteristic domain structure of vertebrate calpains. Transcripts of sacapn1, sacapn2, sacapns1a and sacapns1b had a wide tissue distribution, whereas sacapn3 was almost exclusively detected in skeletal muscle. Next, we assessed transcript expression in skeletal muscle following alteration of nutritional status by (a) fasting and re-feeding or (b) feeding four experimental diets with different carbohydrate-to-protein ratios. Fasting significantly reduced plasma glucose and increased free fatty acids and triglycerides, together with a significant increase in sacapns1b expression. Following 7 days of re-feeding, plasma parameters returned to fed values and sacapn1, sacapn2, sacapns1a and sacapns1b expression was significantly reduced. Furthermore, an increase in dietary carbohydrate content (11 to 39%) diminished growth but increased muscle texture, which showed a significant correlation with decreased sacapn1 and sacapns1a expression, whilst the other calpains remained unaffected. This study has demonstrated that calpain expression is modulated by nutritional status and diet composition in gilthead sea bream, and that the expression of several calpain members is correlated with muscle texture, indicating their potential use as molecular markers for flesh quality in aquaculture production

Transient up- and down-regulation of expression of myosin light chain 2 and myostatin mRNA mark the changes from stratified hyperplasia to muscle fiber hypertrophy in larvae of gilthead sea bream (Sparus aurata L.)

Hyperplasia and hypertrophy are the two mechanisms by which muscle develops and grows. We study these two mechanisms, during the early development of white muscle in Sparus aurata, by means of histology and the expression of structural and regulatory genes. A clear stage of stratified hyperplasia was identified early in the development of gilthead sea bream but ceased by 35 dph when hypertrophy took over. Mosaic recruitment of new white fibers began as soon as 60 dph. The genes mlc2a and mlc2b were expressed at various levels during the main phases of hyperplasia and hypertrophy. The genes myog and mlc2a were significantly up-regulated during the intensive stratified formation of new fibers and their expression was significantly correlated. Expression of mstn1 and igf1 increased at 35 dph, appeared to regulate the hyperplasia-to-hypertrophy transition, and may have stimulated the expression of mlc2a, mlc2b and col1a1 at the onset of mosaic hyperplasia. The up-regulation of mstn1 at transitional phases in muscle development indicates a dual regulatory role of myostatin in fish larval muscle growth. © 2015, Springer-Verlag Berlin Heidelberg

Avaliação de diferentes fontes protéicas sobre o desempenho inicial de larvas do jundiá Rhamdia quelen Evaluation of different sources of protein on the initial performance of south american catfish larvae Rhamdia quelen

O presente estudo foi realizado com o objetivo de avaliar o efeito de diferentes fontes protéicas sobre a sobrevivência e crescimento de larvas de Rhamdia quelen durante as três primeiras semanas de vida. Utilizou-se 3000 larvas distribuídas em 15 grupos, estocadas em condições controladas de cultivo, em um sistema de criação com reutilização de água, termoregulada. As rações testadas eram isoprotéicas com 35% de PB (proteína bruta) e níveis energéticos variando entre 3075 e 3286kcal ED/kg, formuladas com fontes de origem animal, vegetal e pó de levedura Saccharomyces cerevisae. Agranulometria dos alimentos testados foi de 100 a 200mi, 200 a 400mi e 400 a 600mi para as três semanas experimentais, respectivamente. A distribuição do alimento foi feita a vontade entre 8 e 20 horas. No final deste experimento o tratamento T1, contendo figado bovino e levedura, resultou na maior taxa de sobrevivencia (61%) apresentando diferença altamente significativa em relação aos demais tratamentos. Os tratamentos 2 (soja, levedura), 3 (soja, figado bovino), 4 (soja, milho) e 5 (soja, carne, milho) não diferiram significativamente entre si, apresentando baixas taxas de sobrevivência (1,17 a 10,19%). OT1 apresentou o maior comprimento total aos 21 dias, com media individual de 16,46mm, diferindo significativamente dos demais tratamentos. Nestas condições conclui-se que o pó de levedura juntamente com o fígado bovino em rações, proporcionou o melhor desempenho de larvas de jundiá Rhamdia quelen.<br>The experiment was carried out to evaluate the survival and growth of catfish larvae Rhamdia quelen with different sources of protein during the first three weeks of life. Five treatments, with three replications, were tested. A total of 3000 larvae were randomly distributed into 15 groups, maintained under controlled conditions using a termoregulatory water re-use system. The artificial diets tested contained 35% of crude protein and digestible energy varied from 3075 to 3286kcal/kg of dry matter. Granulometry of the ration was 100 to 200mu, 200 to 400mu and 400 to 600mu during the first, second and third week, respectively. The diets were offered ad libitum from 8 am to 8 pm. The treatment 1, containig bovine liver and yeast (Saccharomyces cerevisae), resulted in the highest (P < 0.05) survival rate (61%). The remaining treatments: 2 (soybean, yeast), 3 (soybean, bovine liver), 4 (soybean, corn) and 5 (soybean, meat, corn) did not differ significantly among each other, resulting in low survival rates (1.17 to 10.19%). Larvae of T1 were significantly longer (16.46mm) at 21 days of age than the others. It can be concluded that feeding ration containing bovine liver plus yeast results in could be a good performance of catfish larvae