Lampbrush chromosomes of the Japanese quail (Coturnix coturnix japonica): A new version of cytogenetic maps

Avian oocyte chromosomes are transfomed into giant transcriptionally active lampbrush chromosomes (LBCs) at meiosis 1 diplotene. These chromosomes are a convenient tool for high-resulution cytogenetic analysis. Using differential staining with fluorochromes DAPI and CMA3, we have constructed detailed cytological maps for lampbrush macrochromosomes 1–5 and ZW of the Japanese quail Coturnix coturnix japonica. We also performed a comparative analysis of mitotic chromosomes and LBCs corresponding to them. We estimated the decondensation coefficient during LBC formation and determined the centromere indices for mitotic and diplotene chromosomes and thus found that different chromosomes and chromosomal regions demonstrate unequal degrees of decondensation.