Pterygoplichthys is a genus of related suckermouth armoured catfish native to South America that has invaded tropical and subtropical regions worldwide. Physiological features, including an augmented resistance to organic xenobiotics, may have aided their settlement in foreign habitats. The liver transcriptome of Pterygoplichthys anisitsi was sequenced and used to characterize the diversity of mRNAs potentially involved in the responses to natural and anthropogenic chemicals. In total, 66,642 transcripts were assembled. Among the identified defensome genes, cytochromes P450 (CYP) were the most abundant, followed by nuclear receptors (NR), sulfotransferases (SULT) and ATP binding cassette transporters (ABC). A novel expansion in the CYP2Y subfamily was identified, as well as an independent expansion of the CYP2AAs. Two expansions were also observed among SULT1. Thirty-two transcripts were classified into twelve subfamilies of NR, while 21 encoded ABC transporters. The diversity of defensome transcripts sequenced herein could contribute to this species resistance to organic xenobiotics.

The complete mitogenome of Corydoras nattereri , a species of mailed catfishes from southeastern Brazil, was reconstructed using next-generation sequencing techniques. The mitogenome was assembled using mitochondrial transcripts from the liver transcriptomes of three individuals, and produced a circular DNA sequence of 16,557 nucleotides encoding 22 tRNA genes, two rRNA genes, 13 protein-coding genes and two noncoding control regions (D-loop, OrigL). Phylogeographic analysis of closely related sequences of Cytochrome Oxydase C subunit I (COI) demonstrates high diversity among morphologically similar populations of C. nattereri . Corydoras nattereri is nested within a complex of populations currently assigned to C. paleatus and C. ehrhardti . Analysis of mitogenome structure demonstrated that an insertion of 21 nucleotides between the ATPase subunit-6 and COIII genes may represent a phylogenetically informative character associated with the evolution of the Corydoradinae.

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Hypoptopoma incognitum is a fish of the fifth most species-rich family of vertebrates and abundant in rivers from the Brazilian Amazon. Only two species of Loricariidae fish have their complete mitogenomes sequence deposited in the Genbank. An innovative RNA-based approach was used to assemble the complete mitogenome of H. incognitum with an average coverage depth of 5292×. The typical vertebrate mitochondrial features were found; 22 tRNA genes, two rRNA genes, 13 protein-coding genes, and a non-coding control region. Moreover, the use of this approach allowed the measurement of mtRNA expression levels, the punctuation pattern of editing, and the detection of heteroplasmies.