Accepted_test

Nuclear abundant stable intronic sequences RNA (sisRNAs) produced by a number of transcribed genes in chicken oocyte
by Alla Krasikova | Mikhail Schelkunov | Nadezhda Makarova | Anna Fedotova | Tatiana Kulikova | Anton Fedorov | Saint-Petersburg State University, Saint-Petersburg, Russia | Genomics Core Facility, Skolkovo Institute of Science and Technology, Moscow, Russia | Genomics Core Facility, Skolkovo Institute of Science and Technology, Moscow, Russia | Genomics Core Facility, Skolkovo Institute of Science and Technology, Moscow, Russia | Saint-Petersburg State University, Saint-Petersburg, Russia | Saint-Petersburg State University, Saint-Petersburg, Russia
Abstract ID: 149
Event: BGRS-abstracts
Sections: [Sym 1] Section “Regulatory genomics”

Birds, like many other vertebrates, have a hypertranscriptional type of oogenesis, with an exceptionally high rate of RNA synthesis in the oocyte nucleus. Higher RNA polymerase II velocity directly correlates with the production of newly synthesised circular RNA (circRNAs). Recently, we have undertaken a detailed characterisation of the nuclear and cytoplasmic transcriptome of chicken (Gallus gallus domesticus) oocytes at the lampbrush chromosome stage of oogenesis (bioRxiv. 2024.02.05.577752). Here we aimed to characterise nuclear and cytoplasmic circRNAs including stable intronic sequences RNA. Comparison of the nuclear and cytoplasmic RNA profiles of chicken oocytes revealed the nuclear retention of certain introns in the form of sisRNAs resistant to RNase R treatment. Using CIRCexplorer2, we predicted circRNAs de novo in RNA samples after RNase R treatment, in total and poly(A) RNA libraries. Genomic regions covered by the identified circRNAs include 5'UTR, exonic and intronic regions. RNase R resistant, stable intronic lariats bearing snoRNA or scaRNA are also characterized. We propose that nuclear retained sisRNAs, produced by a number of transcribed genes on the lateral loops of avian and amphibian lampbrush chromosomes via a splicing-dependent mechanism, can maintain the continued transcription of their host genes either at the lampbrush stage of oogenesis or during embryogenesis.