Data from: Small RNAs from a big genome: the piRNA pathway and transposable elements in the salamander species Desmognathus fuscus

Most of the largest vertebrate genomes are found in salamanders, a clade of amphibians that includes 686 species. Salamander genomes range in size from 14 to 120 Gb, reflecting the accumulation of large numbers of transposable element (TE) sequences from all three TE classes. Although DNA loss rates are slow in salamanders relative to other vertebrates, high levels of TE insertion are also likely required to explain such high TE loads. Across the Tree of Life, novel TE insertions are suppressed by several pathways involving small RNA molecules. In most known animals, TE activity in the germline is primarily regulated by the Piwi-interacting RNA (piRNA) pathway. In this study, we test the hypothesis that salamanders' unusually high TE loads reflect the loss of the ancestral piRNA-mediated TE-silencing machinery. We characterized the small RNA pool in the female and male adult gonads, testing for the presence of small RNA molecules that bear the characteristics of TE-targeting piRNAs. We also analyzed the amino acid sequences of piRNA pathway proteins from salamanders and other vertebrates, testing whether the overall patterns of sequence divergence are consistent with conserved pathway function across the vertebrate clade. Our results do not support the hypothesis of piRNA pathway loss; instead, they suggest that the piRNA pathway is expressed in salamanders. Given these results, we propose hypotheses to explain how the extraordinary TE loads in salamander genomes could have accumulated, despite the expression of TE-silencing machinery.ASZ1.nex alignmentNexus file containing the trimmed alignment of amino acid sequences from salamanders and other vertebrates used to generate the phylogeny in the manuscript.Asz1.nexDdx4.nex alignmentDdx4.nexFKBP6.nex alignmentFKBP6.nexHen1.nex alignmentHen1.nexKIF17.nex alignmentKIF17.nexMov10l1.nex alignmentMov10l1.nexPiwil1.nex alignmentPiwil1.nexPiwil2.nex alignmentPiwil2.nexPld6.nex alignmentPld6.nexPrmt5.nex alignmentPrmt5.nexTdrd1.nex alignmentTdrd1.nexTdrkh.nex alignmentTdrkh.nexCryptobranchus pRNA proteinsAmino acid sequences for the 12 Cryptobranchus alleganiensis piRNA pathway proteins.Cryptobranchus_pRNA_proteins.txtFunding provided by: National Science FoundationCrossref Funder Registry ID: http://dx.doi.org/10.13039/100000001Award Number: NSF-DEB 102148