BioProject

Interspecific hybrids are highly complex organisms, especially considering aspects related to the organization of genetic material. More...

Interspecific hybrids are highly complex organisms, especially considering aspects related to the organization of genetic material. The diversity of possibilities created by the genetic combination between different species makes it difficult to establish a large-scale analysis methodology. Colossoma macropomum (Tambaqui) and Piaractus mesopotamicus (Pacu) are species that have similar feeding habits; however, they adapt to different growing temperatures. In addition, they have different growth rates. Tambaqui has a higher growth rate than Pacu, which has better adaptation to lower temperatures. However, considering tambacu, an interspecific hybrid between the two species, it has characteristics that overlap with those observed in Tambaqui and Pacu and, therefore, is more suitable for the cultivation environment. Despite the importance of Pacu, Tambaqui, and tambacu for South American aquaculture programs, genetic information for these genotypes is still highly scarce in specialized databases. Using RNA-Seq analysis, we characterized the transcriptome of white muscle from Pacu, Tambaqui, and their interspecific hybrid (tambacu). The sequencing process allowed identifying a large number of reads. A total of annotated contigs were 37,285, 96,738, and 158,709 for Pacu, Tambaqui, and tambacu. After that, we performed a comparative analysis of the transcriptome of the three genotypes, where we evaluated the differential expression profile of the transcript and the degree of similarity between the nucleotide sequences between the genotypes. We assessed the intensity and pattern of expression across genotypes using differential expression information. Furthermore, we selected some target genes related to essential cellular processes by digital differential expression analysis to evaluate and validate the expression through the RT-qPCR technique. Our results showed that the phenotype presented by tambacu might be associated with changes in the gene expression profile and not necessarily with an increase in gene variability. Thus, the molecular mechanisms underlying these "hybrid effects" may be related to additive and, in some cases, dominant regulatory interactions between parental alleles that act directly on gene regulation in the hybrid transcripts. Less...