Abstract
ABSTRACT This study aimed to evaluate muscle organization in tambaqui in order to describe the muscle growth process. We analyzed the morphometric pattern of fibers from white muscle of young-adults (300 days) by smaller diameter. The organization of white muscle exhibited a typical morphological pattern found in other fish species. Heavier animals showed higher frequency of larger diameter fibers (>50 μm ) and smaller animals had higher frequency of smaller diameter fibers (<20 μm ) (P =0.005). However, both animals showed the same frequency of intermediate diameter fibers (20-50 μm ). Body weight showed a positive correlation with muscle diameter fiber (r=0.45), being 20-50 μm the diameters that contributed the most to animal weight (P <0.0001). A weak correlation between fiber diameter and animal sex was observed (r=0.2). Females showed higher frequency of large fiber diameters (>50 μm ) than males. However, there was no difference between body weight and sex (P =0.8). Our results suggest that muscle growth is by hypertrophy and hyperplasia due to a mosaic appearance from different diameters fibers, which is characteristic of large size fish species.
Highlights
In fish, most species have indeterminate growth, implying that the size is never fixed and some growth continues throughout life (Rescan et al, 2013)
Growth is associated with the recruitment of new fibers and/or the increase in the volume of muscle fibers, such that the muscle may contain fibers with a wide range of diameters
We describe the organization of skeletal muscle from two groups of the same strain showing different growth performances in order to determine muscle growth in 300-days-old tambaqui from captivity
Summary
Most species have indeterminate growth, implying that the size is never fixed and some growth continues throughout life (Rescan et al, 2013). The knowledge on growth of muscle tissue is strategic in aquaculture industry because the muscle growth is directly correlated with the income from fish fillet In this context, some fish species show sexual dimorphism, such as size dimorphism and shape dimorphism, making single-sex rearing more profitable (Mei & Gui, 2015). Growth is associated with the recruitment of new fibers (hyperplasia) and/or the increase in the volume of muscle fibers (hypertrophy), such that the muscle may contain fibers with a wide range of diameters In those fish species that reach a large size, continuous recruitment of muscle fibers in a long-lasting hyperplastic process gives a typical mosaic appearance to muscle cross-sections (Rowlerson & Veggetti, 2001)
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