Cohesion proteins are present in centromere protein bodies associated with avian lampbrush chromosomes
Proteins of sister chromatid cohesion are important for maintenance of meiotic chromosome structure and retention of homologous chromosomes in bivalents during diplotene. Localization of the cohesion proteins within nuclei of growing oocytes merits special attention, particularly in avian oocytes, in which diplotene chromosomes assume the form of lampbrush chromosomes (LBCs). We performed indirect immunostaining using antibodies against cohesins SMC1α, SMC1β, SMC3, Rad21, and the SA/STAG family on chaffinch, pigeon and duck LBCs spreads, and frozen ovary sections. On LBCs spreads, antibodies to the majority of cohesins showed punctate staining on chromosome axes. LBC lateral loops, where sister chromatids are separated, did not show cohesin components. The spherical entities attached to the LBCs centromeres in avian germinal vesicles, the so-called protein bodies (PBs), were enriched in SMC1α, SMC3, Rad21, STAG1 and STAG2. The synaptonemal complex component SYCP3, which also participates in cohesion, was detected in the axes of avian lampbrush bivalents and, to a greater degree, in the PBs. In vitellogenic oocytes, cohesion proteins persist in the PBs associated with condensing bivalents when they concentrate into the karyosphere. These results indicate that cohesion proteins accumulate in centromere PBs in avian oocytes and are involved into structural maintenance of lampbrush chromosome axes.
Key wordsavian oocyte centromere cohesin lampbrush chromosome protein bodies
Unable to display preview. Download preview PDF.
- Callan HG (1986) Lampbrush Chromosomes. Berlin: Springer.Google Scholar
- Dunn, MJ (1993) Gel Electrophoresis: Proteins. Oxford UK: BIOS Scientific Publishers.Google Scholar
- Gall JG (1992) Organelle assembly and function in the amphibian germinal vesicle. Adv Dev Biol 1: 1–29.Google Scholar
- Kropotova EV, Gaginskaya ER (1984) Lampbrush chromosomes from Japanese quail oocytes. Tsitologiia 26: 1008–1014.Google Scholar
- Macgregor, HC, Solovei, I, Mizuno, S, 1997. Lampbrush chromosomes as system for high resolution studies of meiotic chromosome structure. In: Abbondandolo A, Vig BK, Roi R (eds.) Chromosome Segregation and Aneuploidy, pp 172–183. European Commission Joint Research Centre Publication, pp 172–183.Google Scholar
- Solari AJ (1981) Chromosomal axes during and after diplotene. Internatl Cell Biol 80–81: 178–186.Google Scholar
- Tsvetkov AG, Gaginskaya ER (1983) The nuclear matrix of oocytes of the chaffinch (Fringilla coelebs L.) Tsitologiia 25: 649–654.Google Scholar