Análise da expressão diferencial do transcriptoma da espécie Triportheus albus cope, 1872 nas águas preta, clara e branca da Amazônia

Abstract

Thousands of water bodies are found in the Amazon. They can be classified based on their water color in blackwater, clearwater and whitewater. The Amazon basin houses approximately 3,000 fish species, including the freshwater sardine, Triportheus albus, locally known as “sardinha”. Triportheus albus lives in all three types of water, despite their significant differences regarding physicochemical parameters. The ability of this species to survive in these different habitats is anticipated to be related to specific adaptations. The goal of the present study is to describe gene transcription differences of T. albus collected from the three types of water, and to describe the relevant mechanisms behind this ability. Gills of specimens of T. albus from the three types of water (black, clear, and white) were collected. Nine cDNA libraries, three biological replicates for each condition (type of water) were prepared and sequenced for RNA (RNA-Seq) using the MiSeq® (Illumina®) platform. A total of 51.6 million of reads paired-end, were assembled into 285,456 high quality contigs. Considering FDR ≤ 0.05 and the fold change ≥ 2, 13,754 differentially expressed genes were detected for all three conditions. Two mechanisms related to the homeostasis control were detected for T. albus living in blackwater. The acidic blackwater seems to be a challenging environment to many types of organisms. The first mechanism is related to a decrease of cell permeability and the second seem to be related to ion and acid-base regulation. We suggest that T. albus is an important fish species for future studies exploring ion and acid-base regulation in fish of the Amazon.

Key words: Negro River, Tapajós River, Solimões River, differentially expressed genes, RNA-Seq, acid pH, ionic regulation.