Original Article

Discontinuities and unsynapsed regions in meiotic chromosomes have a trans effect on meiotic recombination of some chromosomes in human males
F. Sun^a, M. Oliver-Bonet^a, T. Liehr^b, H. Starke^b, E. Ko^a, A. Rademaker^c, R.H. Martin<sup>a

a</sup>Department of Medical Genetics, University of Calgary, Calgary (Canada)
^bInstitute of Human Genetics and Anthropology, University of Jena, Jena (Germany)
^cDepartment of Preventive Medicine, Northwestern University Medical School, Chicago, IL (USA)

Address of Corresponding Author

Cytogenet Genome Res 2007;119:27-32 (DOI: 10.1159/000109615)

  Abstract.

During meiosis, homologous chromosome pairing and synapsis are essential for subsequent meiotic recombination (crossing-over). Discontinuous regions (gaps) and unsynapsed regions (splits) were most frequently observed in the heterochromatic regions of bivalent synaptonemal complex (SC) 9, and we have previously demonstrated that gaps and splits significantly altered the distribution of MLH1 recombination foci on SC 9. Here, immunofluorescence techniques (using antibodies against SC proteins and the crossover-associated MLH1 protein) were combined with a centromere-specific fluorescence in situ hybridization technique that allows identification of every individual chromosome. The effect of gaps/splits on meiotic recombination patterns in autosomes other than chromosome 9 during the pachytene stage of meiotic prophase was then examined in 6,026 bivalents from 262 pachytene cells from three human males. In 64 analyzed cells with a gapped SC 9, the frequency of MLH1 foci in SCs 5 and 10 and in SC arms 10q, 11p and 16q was decreased compared to 168 analyzed cells with a normally-synapsed SC 9 (controls). In 24 analyzed cells with splits in SC 9, there was a significant reduction in MLH1 focus frequency for SC 5q and the whole SC5 bivalent. The positioning of MLH1 foci on other SCs in cells with gapped/split SC 9 was not altered. These studies suggest that gaps and splits not only have a cis effect, but may also have a trans effect on meiotic recombination in humans.

Copyright © 2007 S. Karger AG, Basel

  Author Contacts

Request reprints from Renée H. Martin
Department of Medical Genetics, University of Calgary
3330 Hospital Dr, NW Calgary (Canada)
telephone: +1 403 220 7520; fax: +1 403 210 7931
e-mail: rhmartin@ucalgary.ca

  Article Information

R.H.M. holds a Canada Research Chair in Genetics, and the research was funded by the Canadian Institutes of Health Research (CIHR) grant MA7961. F.S. and M.O.-B are recipients of a CIHR Strategic Training Fellowship in Genetics, Child Development and Health. T.L. is supported in part by the EU (ICA2-CT-2000-10012), the Evangelische Studienwerk e.V. Villigst and the Ernst-Abbe-Stiftung.

Manuscript received 4 January 2007
Accepted in revised form for publication by M. Schmid,: 15 May 2007.
Published online: December 14, 2007
Number of Print Pages : 6
Number of Figures : 2, Number of Tables : 2, Number of References : 36