Degree of piRNA sharing and Piwi gene expression in the skeletal muscle of Piaractus mesopotamicus (pacu), Colossoma macropomum (tambaqui), and the hybrid tambacu.

PiRNAs are a class of small noncoding RNAs that, in their mature form, bind to Piwi proteins to repress transposable element activity. Besides their role in gametogenesis and genome integrity, recent evidence indicates their action in non-germinative tissues. We performed a global analysis of piRNA and Piwi gene expression in the skeletal muscle of juveniles pacu (Piaractus mesopotamicus), tambaqui (Colossoma macropomum), and the hybrid tambacu to evaluate the degree of piRNA sharing among these three genotypes. Total RNA was sequenced and analyzed using specific parameters of piRNAs by bioinformatics tools. piRNA and Piwi gene expression was analyzed by RT-qPCR. We detected 24 piRNA clusters common to the three genotypes, with eight shared between pacu and tambacu, three between pacu and tambaqui, and five between tambaqui and tambacu; seven, five, and four clusters were unique to pacu, tambacu, and tambaqui, respectively. Genomic localization and fold change values showed two clusters and 100 piRNAs shared among the three genotypes. The gene expression of four piRNAs was evaluated to validate our bioinformatics results. piRNAs from cluster 17 were higher in tambacu than pacu and piRNAs from cluster 18 were more highly expressed in tambacu than tambaqui and pacu. In addition, the expression of Piwis 1 and 2 was higher in tambacu and tambaqui than pacu. Our results open an important window to investigate whether these small noncoding RNAs benefit the hybrid in terms of faster growth and offer a new perspective on the function of piRNAs and Piwis in fish skeletal muscle.

The combination of resveratrol and exercise enhances muscle growth characteristics in pacu (Piaractus mesopotamicus).

Pacu is a tropical fish with important value to aquaculture. During cellular metabolism, reactive oxygen species (ROS) are produced, which can influence muscle growth. Resveratrol is an effective antioxidant that scavenges ROS and can modulate physical performance preventing oxidative stress. We investigated the effects of resveratrol and exercise on pacu muscle growth characteristics. Four groups were used: fish fed with control diet /without exercise (C); fish fed with control diet/subjected to exercise (CE); fish fed resveratrol-supplemented diet/without exercise (R); and fish fed resveratrol-supplemented diet/subjected to exercise (RE). At 30 days, the RE group presented a significant increase in body weight, fewer muscle fibers in the 20-40 µm and more fibers in the >60 µm diameter class compared to the C group. At day 7, catalase activity decreased in CE and RE groups. Superoxide dismutase activity decreased only in the CE group. Myod and mtor gene expression was higher in R and RE and igf-1 was up-regulated in the RE group. Murf1a level decreased in CE, R, and RE, while sdha expression was higher in the RE group. We suggest that resveratrol in combination with exercise was beneficial for muscle growth and metabolism, increasing the expression levels of genes related to muscle anabolism and oxidative metabolism, besides the decrease of catabolic gene expression. Notably, all of these changes occurred together with muscle hypertrophy and increased body weight. Our results show a positive application for resveratrol in association with exercise as a strategy to improve the growth performance of juvenile pacus.

High Final Energy of Low-Level Gallium Arsenide Laser Therapy Enhances Skeletal Muscle Recovery without a Positive Effect on Collagen Remodeling.

The aim of this study was to evaluate the effects of a Gallium Arsenide (GaAs) laser, using a high final energy of 4.8 J, during muscle regeneration after cryoinjury. Thirty Wistar rats were divided into three groups: Control (C, n = 10); Injured (I, n = 10) and Injured and laser treated (Injured/LLLT, n = 10). The cryoinjury was induced in the central region of the tibialis anterior muscle (TA). The applications of the laser (904 nm, 50 mW average power) were initiated 24 h after injury, at energy density of 69 J cm(-1) for 48 s, for 5 days, to two points of the lesion. Twenty-four hours after the final application, the TA muscle was removed and frozen in liquid nitrogen to assess the general muscle morphology and the gene expression of TNF-α, TGF-ß, MyoD, and Myogenin. The Injured/LLLT group presented a higher number of regenerating fibers and fewer degenerating fibers (P < 0.05) without changes in the collagen remodeling. In addition, the Injured/LLLT group presented a significant decrease in the expression of TNF-α and myogenin compared to the injured group (P < 0.05). The results suggest that the GaAs laser, using a high final energy after cryoinjury, promotes muscle recovery without changing the collagen remodeling in the muscle extracellular matrix.