Nonhomologous Chromosome Interactions in Prophase I: Dynamics of Bizarre Meiotic Contacts in the Alay Mole Vole Ellobius alaicus (Mammalia, Rodentia)

Abstract

Nonhomologous chromosome interactions take place in both somatic and meiotic cells. Prior to this study, we had discovered special contacts through the SYCP3 (synaptonemal complex protein 3) filament between the short arms of nonhomologous acrocentrics at the pachytene stage in the Alay mole vole, and these contacts demonstrate several patterns from proximity to the complete fusion stage. Here, we investigated the nonhomologous chromosome contacts in meiotic prophase I. It turned out that such contacts do not introduce changes into the classic distribution of DNA double-strand breaks. It is noteworthy that not all meiotic contacts were localized in the H3k9me3-positive heterochromatic environment. Both in the mid zygotene and in the early–mid diplotene, three types of contacts (proximity, touching, and anchoring/tethering) were observed, whereas fusion seems to be characteristic only for pachytene. The number of contacts in the mid pachytene is significantly higher than that in the zygotene, and the distance between centromeres in nonhomologous contacts is also the smallest in mid pachytene for all types of contacts. Thus, this work provides a new insight into the behavior of meiotic contacts during prophase I and points to avenues of further research.

Speciation on the Roof of the World: Parallel Fast Evolution of Cryptic Mole Vole Species in the Pamir-Alay—Tien Shan Region

“…It is noteworthy that chromosome contacts in meiosis have been described in E. alaicus in some localities of the Alay Valley. They are considered as a possible mechanism of Robertsonian translocations [ 36 , 37 ]. However, in none of Tien Shan mole vole populations we were able to find individuals with such chromosome contacts in meiotic prophase I.…”

Chromosomal Instability in Genome Evolution: From Cancer to Macroevolution

“…Robertsonian (Rb) chromosome fusions, expanded upon at a later point, are another example. Further of their impact in fertility, their consequent secondary defects in synapsis leads to chromosomal incompatibilities between divergent lineages, thus contributing to chromosomal speciation, as it has been described in the Alai mole vole (Ellobius alaicus) in the family Cricetidae [101].…”