Comparative and integrative analysis of the transcriptome and the microRNAoma in skeletal muscle of Colossoma macropomum (tambaqui), Piaractus mesopotamicus (pacu) and its hybrid, tambacu: molecular, in silico, in vitro and in vivo approaches.

Abstract

Colossoma macropomum (tambaqui) and Piaractus mesopotamicus (pacu) have wide acceptance in the market, especially because they have desirable characteristics for the production environment. Although these species have similar eating habits, there are wide variations related to adaptation to cultivation temperature and growth rate. Tambaqui has a higher growth rate compared to pacu which has a greater adaptation to lower temperatures. However, considering the tambacu, resulted from the hybridization between tambaqui and pacu, this presents characteristics that overlap those observed in tambaqui and pacu, and therefore, most suitable for the cultivation environment. Despite the importance of pacu, tambaqui and tambacu for Brazilian aquaculture programs, genetic information for these genotypes are extremely scarce in specialized databases. In this sense, we intend to characterize the transcriptome (RNA transcripts) and microRNAome in the white muscle of the three genotypes. After this, an integrative and comparative analysis of the transcriptome and microRNAome of the three genotypes will be accomplished with the following specific objectives: (i) Identify the differential expression profile of the transcript and microRNA sequences in each parental genotype (pacu and tambaqui) compared to hybrid (tambacu); (ii) evaluate of similarity degree between the nucleotide sequences among genotypes; (iii) performing the signalling pathways prediction and construction of microRNA-mRNA interaction networks involved with the development, growth and maintenance of muscle phenotype among genotypes; (iv) identify potential biomarkers or genetic targets related to hybrid vigor presented by tambacu; (v) evaluate the expression of microRNA and the main transcripts through RTqPCR, and the biomarkers identified after comparing the three genotypes; (vi) establish the primary culture of myoblasts in tambaqui and tambacu and (vii) corroborating data obtained from the differential expression profiling, prediction signaling pathways and networks of microRNA-mRNA interaction (in silico analysis) among the three genotypes in cell culture of myoblasts. Our results will contribute to a better understanding of the biological processes related to the higher growth rate of tambaqui and the better adaptation to low temperatures observed in pacu. Considering the more specific results with better applicability we expected to identify potential biomarkers and/or targets gene related to hybrid vigor presented by tambacu. Also, relevant data regarding the pattern of mRNAs and microRNAs expression between genotypes will be obtained, with emphasis on the sequences related to muscle growth. (AU)