MEIOSIS

Sexual reproduction is a critical prerequisite to maintain species over long periods of time. It is the solution for maintaining populations despite the mortality of individuals. Importantly, sexual reproduction also promotes the genetic diversity essential for evolution through natural selection. Central to sexual reproduction is a specialized cell division called meiosis, during which the double chromosome set (one originally inherited from each parent) is halved and distributed equally into gametes (egg and sperm cells in humans) [Figure 1]. Two gametes of opposite sex in turn fuse to form a zygote, a single cell with two, re-assorted chromosome complements that will eventually multiply to produce a new individual.

Meiosis is a highly organized and tightly regulated developmental program during which chromosomes are deliberately broken and subsequently repaired [Figure 2]. The repair process is used to physically connect the equivalent maternal and paternal chromosomes, thereby recombining different versions of genes (alleles). This recombination generates offspring with newly combined parental traits. It is also essential for the subsequent chromosome segregation process, which yields cells with single chromosome complements - the gametes [compare Figures 1 and 3]. Disturbances of this meiotic program have been reported to cause miscarriages and hereditary disorders.

A large set of specialized proteins is essential to meiosis. Some of them induce the breakage and others coordinate the subsequent repair in a fashion different from that in normal body cells. Hence, the production of these meiosis-specific proteins, which could cause chromosome breakage and types of illegitimate repair, must be avoided in somatic cells. Indeed, the production in normal body cells of some of these key regulators of meiosis-specific repair has been linked to certain common cancer types. Therefore, a detailed understanding of meiosis as a basic biological process has evidently wide implications critical to human health and wellbeing.

The overall mechanism of meiotic recombination and the factors regulating it are conserved between all eukaryotes, including humans.

My lab is interested in and studies aspects of meiotic recombination and chromosome organisation using the fission yeast, Schizosaccharomyces pombe, as a model organism.

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