Influence of rearing temperature on muscle growth and adipose tissue in Nile tilapia (Oreochromis niloticus) strains

<div><p>ABSTRACT. This study aimed to evaluate the effect of temperature on the tissue growth of Red, GIFT and Supreme tilapia strains. Fingerlings of approximately 1.4 g from male populations were reared for a period of 60 days, in three recirculating systems, each system containing 6 water tanks of 0.5 m³, at three temperatures (22, 28 and 30ºC). Ten fish of each recirculation system and each temperature studied were sampled. Fishes have been anesthetized, euthanized and weighed. The samplings have been done from the dorsal musculature, caudal, visceral and ventral subcutaneous adipose tissue. Histological sections were prepared and evaluated to determine the diameter of the cells. The experimental design was completely randomized factorial 3 X 3 (strain X temperature). Analysis of variance was performed and means were compared. Higher weights were found for fish reared at 30°C (56.23 g) compared to those grown at 28 (42.12 g) or 22°C (10.52 g). The cooled water temperature (22°C) may have contributed to the hypertrophy of white muscle fibers and visceral adipocytes from tilapia, compared to 28 or 30ºC. Red Tilapia, GIFT and Supreme strains show differences in muscle growth and adipose tissues in response to temperature of cultivation.</p></div

Ascorbic Acid Supplementation Improves Skeletal Muscle Growth in Pacu (Piaractus mesopotamicus) Juveniles: In Vivo and In Vitro Studies

In fish, fasting leads to loss of muscle mass. This condition triggers oxidative stress, and therefore, antioxidants can be an alternative to muscle recovery. We investigated the effects of antioxidant ascorbic acid (AA) on the morphology, antioxidant enzyme activity, and gene expression in the skeletal muscle of pacu (Piaractus mesopotamicus) following fasting, using in vitro and in vivo strategies. Isolated muscle cells of the pacu were subjected to 72 h of nutrient restriction, followed by 24 h of incubation with nutrients or nutrients and AA (200 µM). Fish were fasted for 15 days, followed by 6 h and 15 and 30 days of refeeding with 100, 200, and 400 mg/kg of AA supplementation. AA addition increased cell diameter and the expression of anabolic and cell proliferation genes in vitro. In vivo, 400 mg/kg of AA increased anabolic and proliferative genes expression at 6 h of refeeding, the fiber diameter and the expression of genes related to cell proliferation at 15 days, and the expression of catabolic and oxidative metabolism genes at 30 days. Catalase activity remained low in the higher supplementation group. In conclusion, AA directly affected the isolated muscle cells, and the higher AA supplementation positively influenced muscle growth after fasting

Relative expression of miR-499 and the <i>sox6</i> mRNA between fast- and slow-twitch muscles in 150-day-old and 2-year-old pacus.

<p>miR-499 and <i>sox6</i> mRNA expression was assessed by qPCR in skeletal muscle from 150-day-old juvenile (150 d) and 2-year-old adult (2 y) pacus. The skeletal muscle was analyzed only in the 150-day-old and 2-year-old pacus given the difficulty in isolating the slow-twitch muscle in younger animals (30- and 90-day-old pacus). The data are expressed as the fold change compared with the expression level in the fast-twitch muscle. The data are presented as the mean ± SEM (n = 6). The different letters indicate significant differences in expression (p<0.05).</p

Relative expression of the <i>myod</i> and <i>myogenin</i> mRNAs in pacu myoblast cell cultures.

<p><i>myod</i> and <i>myogenin</i> mRNAs expression was assessed by qPCR in primary myoblast cultures isolated from fast-twitch muscle of juvenile pacus at different phases: 2–4 days (2–4 d), 5–8 days (5–8 d) and 9–12 days (9–12 d). The data are expressed as the fold change compared with the expression level at 2–4 days. The data are presented as the mean ± SEM from 3 independent cell cultures. The different letters indicate significant differences in expression (p<0.05).</p

Relative expression of miR-206 and the <i>pax7</i> mRNA in fast- and slow-twitch muscles of pacu during growth.

<p>miR-206 and <i>pax7</i> mRNA expression was assessed by qPCR in pacu skeletal muscle at different development stages: 30-day-old larvae (30 d), 90-day-old juveniles (90 d), 150-day-old juveniles (150 d) and 2-year-old adults (2 y). The slow-twitch muscle was analyzed only in the 150-day-old and 2-year-old pacus, given the difficulty in isolating this tissue in younger animals (30- and 90-day-old pacus). The data are expressed as the fold change compared with the expression level in the fast-twitch muscle in the 30-day-old pacus or the expression level in the slow-twitch muscle in the 150-day-old pacus. The data are presented as the mean ± SEM (n = 6). The different letters indicate significant differences in expression (p<0.05).</p