The new yeast is a mouse!

In many organisms including yeast, mice, and humans, an essential feature of meiosis is genetic recombination. Recombination creates diversity by mixing the genetic information from each parent into new combinations. Recombination events can be either a reciprocal exchange of DNA called a crossover or a nonreciprocal exchange called a gene conversion or noncrossover (Figure 2). It is the crossovers that become part of a physical structure called chiasmata, which ensures that the homologous chromosomes go to opposite poles and thus partition properly. Because of this essential role, organisms have developed mechanisms (interference [1] and crossover homeostasis [2]) to distribute crossovers nonrandomly within and between chromosomes, such that each chromosome gets at least one crossover (the “obligate” chiasmata [3]). The molecular basis and the relationship between these mechanisms are poorly understood. [taken from introduction]