Piscine orthoreovirus (PRV) belongs to the family Reoviridae and has been described mainly in association with salmonid infections. The genome of PRV consists of about 23,600 bp, with 10 segments of double-stranded RNA, classified as small (S1 to S4), medium (M1, M2 and M3) and large (L1, L2 and L3); these range approximately from 1000 bp (segment S4) to 4000 bp (segment L1). How the genetic variation among PRV strains affects the virulence for salmonids is still poorly understood. The aim of this study was to describe the molecular phylogeny of PRV based on an extensive sequence analysis of the S1 and M2 segments of PRV available in the GenBank database to date (May 2020). The analysis was extended to include new PRV sequences for S1 and M2 segments. In addition, subgenotype classifications were assigned to previously published unclassified sequences. It was concluded that the phylogenetic trees are consistent with the original classification using the PRV genomic segment S1, which differentiates PRV into two major genotypes, I and II, and each of these into two subgenotypes, designated as Ia and Ib, and IIa and IIb, respectively. Moreover, some clusters of country- and host-specific PRV subgenotypes were observed in the subset of sequences used. This work strengthens the subgenotype classification of PRV based on the S1 segment and can be used to enhance research on the virulence of PRV.

Phosphate and arsenate are very similar compounds, and there is great interest in studying their relationship and their interaction with biological systems. Despite having no apparent biological function, specific genes regulate arsenic interaction with cells and can be located in regions of the genome called arsenic islands, where phosphate metabolism genes are also present. Although they are neighboring genes, the nature of their relationship and how they have been selected is still unknown.In this work, we analyzed the metagenomes of the four microbial ecosystems inhabiting hypersaline lakes of the Argentine Puna and the Atacama salt flat in Chile and have evaluated the presence and abundance of both arsenic and phosphate metabolism genes. The samples analyzed included microbialites, biofilms and microbial mats; all of them established under high arsenic concentrations, high UV radiation and high temperature fluctuation, among others.The results show great differences in the dispersion and abundance of genes related to both phosphate and arsenic metabolism in the analyzed samples. The main difference is given in the Diamante Lake, located in the crater of the Galan volcano characterized by being one of the lakes with the highest arsenic concentration (2.34 mM). Correlating genes abundance with the physicochemical parameters of the lakes studied, our results suggest that arsenic and phosphate metabolism are intricately co-regulated in environmental conditions.