Male Mouse Recombination Maps for Each Autosome Identified by Chromosome Painting

Abstract

Linkage maps constructed from genetic analysis of gene order and crossover frequency provide few clues to the basis of genomewide distribution of meiotic recombination, such as chromosome structure, that influences meiotic recombination. To bridge this gap, we have generated the first cytological recombination map that identifies individual autosomes in the male mouse. We prepared meiotic chromosome (synaptonemal complex [SC]) spreads from 110 mouse spermatocytes, identified each autosome by multicolor fluorescence in situ hybridization of chromosome-specific DNA libraries, and mapped >2,000 sites of recombination along individual autosomes, using immunolocalization of MLH1, a mismatch repair protein that marks crossover sites. We show that SC length is strongly correlated with crossover frequency and distribution. Although the length of most SCs corresponds to that predicted from their mitotic chromosome length rank, several SCs are longer or shorter than expected, with corresponding increases and decreases in MLH1 frequency. Although all bivalents share certain general recombination features, such as few crossovers near the centromeres and a high rate of distal recombination, individual bivalents have unique patterns of crossover distribution along their length. In addition to SC length, other, as-yet-unidentified, factors influence crossover distribution leading to hot regions on individual chromosomes, with recombination frequencies as much as six times higher than average, as well as cold spots with no recombination. By reprobing the SC spreads with genetically mapped BACs, we demonstrate a robust strategy for integrating genetic linkage and physical contig maps with mitotic and meiotic chromosome structure.

Predicting and Testing Physical Locations of Genetically Mapped Loci on Tomato Pachytene Chromosome1

“…The last requirement is the most problematic since few RN-cM maps have been prepared. However, maps of Mlh1 fluorescent foci on pachytene chromosomes (Froenicke et al 2002) are a reasonable substitute in mammals and birds because in these animals Mlh1 foci correspond to RNs (Barlow and Hultén 1998;Anderson et al 1999;Pigozzi 2001;Marcon and Moens 2003). On the other hand, this does not seem to be case in tomato where Lhuissier et al (2007) report 30% fewer Mlh1 foci than RNs on pachytene chromosomes.…”

Meiotic Recombination at the Ends of Chromosomes inSaccharomyces cerevisiae

“…Such juxtaposition could enhance crossing over. Alternatively, higher crossover frequencies near chromosome ends could be the result of crossover interference, which has been suggested to spread the distribution of crossovers distally in higher eukaryotes (Lawrie et al 1995;Barlow and Hulten 1998;Froenicke et al 2002).…”

The diverse roles of transverse filaments of synaptonemal complexes in meiosis

“…2) (Froenicke et al 2002;Fung et al 2004), or RNs (Sherman and Stack 1995) (Table 2). The various methods of determination of CO positions each have their own advantages and disadvantages: chiasmata can only be analyzed in organisms with favorable chromosome morphology; analysis of recombinant progeny usually covers only part of the genome, has a low spatial resolution, and requires that meiosis is completed and yields viable products; and there is no guarantee that all foci or RNs will yield COs. We will therefore distinguish between estimations of interference based on analyses of recombinant progeny or tetrads (genetic interference), chiasma positions (chiasma interference), or positions of foci or RNs (cytological interference) (Fung et al 2004).…”