Searching for RNA polymerase II promoter regions responsible for transcription on lampbrush chromosomes in chicken (Gallus gallus)

Lampbrush chromosomes (LBCs) are specific form of chromosomes during meiosis in oocytes of most vertebrates, including birds. They appear as half-bivalent with chromomere-loop organization. The prominent structure of the LBCs loops is maintained by a high density of transcripts mainly produced by RNA polymerase II. Despite years of research, the reason of such an intense transcription in the meiotic diplotene I is unknown and most transcribed sequences themselves and their biological role still need to be clarified. We aimed to identify promotor regions of lateral loops on chicken (Gallus gallus domesticus) LBCs.

Primarily we used previously obtained data of localization of chicken genome BAC clones from WAG-library on LBCs using fluorescent in situ hybridization. Four BAC clones mapped on chicken genome by microsatellite markers and localized exactly at LBCs transcriptionally active loops were selected for bioinformatics analysis. Because of absence of BAC clones sequences we used the latest chicken genome assembly Gallus_gallus-5.0, data about microsatellite markers and average length of WAG-clones to identify sequences of selected BAC clones in contigs. Though comparison of probable clone sequences with ovary transcriptome using Geneious software we identified strand transcribed during LBCs stage. According to previous studies chicken promotor regions differ from mammalian so we localized CpG-islands, G-quadruplexes and STR regions associated with chicken promoters using Newcpgreport, QGRS Mapper and GMAT software. Consequently, we found from one to three possible promotors regions for each lateral loop. We suggest that identified promoter regions are involved in initialization of transcription on LBCs lateral loops.

   Дарья Алешкина
   Алсу Сайфитдинова
Время выполнения проекта: Feb 2017 — Jun 2017