Tandem 41-bp repeats in chicken and Japanese quail genomes: FISH mapping and transcription analysis on lampbrush chromosomes
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The chromosomal distribution of 41-bp repeats, known as CNM and PO41 repeats in the chicken genome and BglII repeats in the Japanese quail, was analyzed precisely using giant lampbrush chromosomes (LBC) from chicken, Japanese quail, and turkey growing oocytes. The PO41 repeat is conserved in all galliform species, whereas the other repeats are species specific. In chicken and quail, the centromere and subtelomere regions share homologous satellite sequences. RNA polymerase II transcribes the 41-bp repeats in both centromere and subtelomere regions. Ongoing transcription of these repeats was demonstrated by incorporation of BrUTP injected into oocytes at the lampbrush stage. RNA complementary to both strands of CNM and PO41 repeats is present on chicken LBC loops, whereas strand-specific G-rich transcripts are characteristic of BglII repeats in the Japanese quail. The RNA from 41-bp repeats does not undergo cotranscriptional U snRNP-dependent splicing. At the same time, the ribonucleoprotein matrix of transcription units with C-rich RNA of CNM and PO41 repeats was enriched with hnRNP protein K. Potential promoters for satellite transcription are discussed.
KeywordsLong Terminal Repeat Japanese Quail Lateral Loop Mitotic Metaphase Chromosome Long Terminal Repeat Promoter
We gratefully acknowledge the following people for providing antibodies: J. L. Barbero (Centro Nacional de Biotecnologia, Madrid, Spain), M. V. Filatov (Saint-Petersburg Institute of Nuclear Physics, Russia), J. G. Gall (Carnegie Institution of Washington, Baltimore, MD, USA), and U. Scheer and R. Hock (University of Wuerzburg, Germany). We are grateful to J. G. Gall for the critical reading and careful editing of the manuscript. We would like to thank our former graduate student A. Kurganova for her assistance in some experiments. This work was supported by the Russian Foundation for Basic Research (grant 05-04-48252). We used the equipment of the Core Facility “CHROMAS” (Biological Institute, Saint-Petersburg State University).
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