Molecular features of meiotic recombination hot spots

Abstract

Meiotic recombination occurs preferentially at certain regions called hot spots and is important for generating genetic diversity and proper segregation of chromosomes during meiosis. Hot spots have been characterized most extensively in yeast, mice and humans. The development of methods based on sperm typing and population genetics has facilitated rapid and high-resolution mapping of hot spots in mice and humans in recent years. With increasing information becoming available on meiotic recombination in different species, it is now possible to compare several molecular features associated with hot-spot loci. Further, there have been advances in our knowledge of the factors influencing hot-spot activity and the role that they play in structuring the genome into haplotype blocks. We review the molecular features associated with hot spots in terms of their properties and mechanisms underlying their function and distribution. A large number of these features seem to be shared among hot spots from different species suggesting common mechanisms for their formation and function.

Important Characteristics of Sequence-Specific Recombination Hotspots in Schizosaccharomyces pombe

“…In both Saccharomyces cerevisiae and Schizosaccharomyces pombe, and probably other organisms, recombination is initiated by the formation of double strand DNA breaks (DSBs) (Gerton et al 2000;Mahadevaiah et al 2001;Cromie et al 2007). In many organisms, including humans, mice, and both the budding and fission yeasts, these DSBs occur preferentially at so-called hotspots (Petes 2001;Kauppi et al 2004;Nishant and Rao 2005). Although the distribution of DSBs can vary widely across the genome, the distribution of interhomolog crossovers, at least in S. pombe, is considerably more uniform due to the preferential selection of the sister chromatid for DSB repair at strong DSB hotspots (Hyppa and Smith 2010).…”

Meiotic Chromosome Abnormalities and Spermatic FISH in Infertile Patients with Normal Karyotype

“…It takes place predominantly in genomic loci, termed hotspots, close to the telomeres (Lynn et al, 2004). The DSB is an indicator of high genetic exchange activity in the hotspots and is not distributed either randomly or uniformly (Petes, 2001;Nishant and Rao, 2006;Buard and de Massy, 2007).…”

“…Crossovers are more frequent close to the telomeres (Lynn et al, 2004). They are the basis of chiasmata (crossings) observed with the optical microscope (Nishant and Rao, 2006). Only two homologous chromatids intersect in each chiasma.…”

Cut Thy Neighbor: Cyclic Birth and Death of Recombination Hotspots via Genetic Conflict

“…They are numerous and highly dispersed throughout the genomes of all species that have been studied, with .25,000 hotspots estimated to occur in humans (Myers et al 2006). The locations of well-characterized hotspots have diverged between humans and chimps, as has the recombinational landscape of closely related Drosophila species, indicating that hotspots may arise and go extinct on a timescale of less than several million years (reviewed in Nishant and Rao 2006).…”

“…The molecular process by which recombinational hotspots are created is not known (Nishant and Rao 2006). Nonetheless, some associations have been established.…”