Abstract
Abstract
Guppy X and Y chromosomes represent an early stage in sex chromosome divergence. Synapsis and recombination between X and Y chromosomes attract special attention because recombination suppression promotes their differentiation, but previous studies have given contradictory results. Linkage analysis indicated that recombination between X and Y was extremely rare (<10%) and occurred in the medial part of the Y chromosome, while cytological analysis demonstrated regular association between the distal ends of the X and Y at diakinesis. In this study, we examine pairing and recombination between X and Y chromosomes using immunolocalization of MLH1 to mark recombination nodules, and genomic in situ hybridization with a male DNA probe to identify the Y-specific heterochromatic region. Pairing between X and Y is initiated distally. Single crossovers were detected in 87% of XY synaptonemal complexes, most often in the distal region and less frequently in a median position indicating that end-to-end associations between X and Y are chiasmatic. Thus, we suggest that the very low frequency of recombination detected by linkage analysis in a previous study resulted from a lack of informative markers in distal regions.
Get full access to this article
View all access options for this article.
References
Supplementary Material
Please find the following supplemental material available below.
For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.
For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.
