Characterization of α-actin isoforms in white and red skeletal muscle types of Leporinus macrocephalus (Characiformes, Anostomidae).

Fernanda A Alves-Costa,Adriane P Wasko,Maeli D.P Silva

doi:10.1590/0001-3765201520140278

Fernanda A Alves-Costa, Adriane P Wasko + Show 1 more

Open Access

https://doi.org/10.1590/0001-3765201520140278

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Abstract

Two α-actin genes of the fish Leporinus macrocephalus, referring to white and red muscle tissues, were isolated. Actin isoforms, that mainly differed by a Ser/Ala155 substitution, can have a functional significance related to actin-ATP interaction. An Ala155 residue, as observed in the α-skeletal actin from red muscle, results in a decrease in actin's affinity for ATP, which may also be associated to the slow contractile performance of this tissue. Furthermore, a Phe/Ile262 substitution at the red muscle actin leads to a hydrophobicity variation at the D-plug of the protein, which could alter its stability. Data on qRT-PCR evidenced a significant higher actin mRNA level in white muscle when compared to red muscle (T=105 Mann Whitney; p<0.001). This finding could be related to the energetic demands of the white muscle tissue, with fast contraction fibers and glycolytic metabolism for energy supply. Available data on muscle actins lead to the proposal that white and red α-skeletal actins are genetically and functionally distinguishable in fish species, a feature that is not found in other vertebrate groups.

Highlights

Muscles are a major source of energy consumption and heat generation and, there has been a longstanding interest in the mechanisms that under lie muscle energetic properties
In order to investigate if specific actin isoforms related to white and red muscles can be found in distinct teleost fish, the purpose of the present study was the isolation, characterization and development of gender expression analysis on skeletal muscle actin genes of Leporinus macrocephalus, a species that has been intensively exploited in subtropical aquaculture as a food resource
Nucleotide sequence analysis allowed the characterization of two distinct segments composed by 472 bp, related to actin genes from white and red muscles

Summary

Introduction

Muscles are a major source of energy consumption and heat generation and, there has been a longstanding interest in the mechanisms that under lie muscle energetic properties. Body mass is mainly composed by a skeletal musculature that constitutes 40-75% of the total weight of the animal. This tissue is composed by different muscle fibers that occupy distinct axial regions - a large portion of a deeper layer of white muscle WASKO metabolism, for energy supply), a superficial thin layer of red muscle (with slow contraction fibers and oxidative metabolism), and an intermediate layer between the red and white musculatures (with fibers of fast contraction and oxidative/ glycolytic metabolism). While white muscle fibers are associated to fast swimming behaviors in fish, as predation and escape, the red muscle fibers are correlated to slow movements, as migration and foraging habits (Luther et al 1995, Sänger and Stoiber 2001)

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