The Trajectory of KoRV-A Evolution Indicates Initial Integration into the Koala Germline Genome Near Coffs Harbour.

Background Koala Retrovirus-A is a gamma-retrovirus that is spreading across wild koala populations through horizontal and vertical transmission, contributing significantly to genomic diversity across and even within koala populations. Previous studies have estimated that KoRV-A initially integrated into the koala genome less than 50,000 years ago, but the precise origins and the patterns of spread after its endogenization remain unclear. Results In this study, we analyzed germline insertions of KoRV-A using whole-genome sequencing data from 405 wild koalas, representing nearly the species' entire geographic range.

piRNA-Guided Transposon Silencing and Response to Stress in Germline.

Transposons are integral genome constituents that can be domesticated for host functions, but they also represent a significant threat to genome stability. Transposon silencing is especially critical in the germline, which is dedicated to transmitting inherited genetic material. The small Piwi-interacting RNAs (piRNAs) have a deeply conserved function in transposon silencing in the germline.

Aub, Vasa and Armi localization to phase separated nuage is dispensable for piRNA biogenesis and transposon silencing in .

From nematodes to placental mammals, key components of the germline transposon silencing piRNAs pathway localize to phase separated perinuclear granules. In the PIWI protein Aub, DEAD box protein Vasa and helicase Armi localize to nuage granules and are required for ping-pong piRNA amplification and phased piRNA processing. piRNA mutants lead to genome instability and Chk2 kinase DNA damage signaling.

Epigenetic and chromosomal features drive transposon insertion in Drosophila melanogaster.

Transposons are mobile genetic elements prevalent in the genomes of most species. The distribution of transposons within a genome reflects the actions of two opposing processes: initial insertion site selection, and selective pressure from the host. By analyzing whole-genome sequencing data from transposon-activated Drosophila melanogaster, we identified 43 316 de novo and 237 germline insertions from four long-terminal-repeat (LTR) transposons, one LINE transposon (I-element), and one DNA transposon (P-element).

Somatic piRNAs and Transposons are Differentially Expressed Coincident with Skeletal Muscle Atrophy and Programmed Cell Death.

PIWI-interacting RNAs (piRNAs) are small single-stranded RNAs that can repress transposon expression epigenetic silencing and transcript degradation. They have been identified predominantly in the ovary and testis, where they serve essential roles in transposon silencing in order to protect the integrity of the genome in the germline. The potential expression of piRNAs in somatic cells has been controversial.