![]() ( e) Crossover number distribution from two artificial datasets generated by simulations. ( d) When more (less) precursors exist, there would be more (less) precursors suppressed by crossover interference, however, crossover number is maintained less altered. The next crossover if occurs would occur far away from the existed ones to fill in the holes. Among a large number of crossover precursors (DSB mediated inter-homolog interactions), the most sensitive one is first designated and crossover interference spreads out to inhibit a second crossover nearby. Sisters are locally separated around chiasmata. ( b) Homologs are linked together by chiasmata combined with global sister cohesion. Multiple chiasmata (crossovers) are evenly spaced (long arrows). The copyright license of reproducing this picture was received from the publisher John Wiley and Sons. ( a) A spread nucleus of the locust Schistocerca gregaria to show chiasmata. Here, current advances in the understanding of these issues are reviewed, regulation of crossover patterns by meiotic chromosomes are discussed, and issues that remain to be investigated are suggested.Īneuploidy chromosome crossover crossover interference crossover pattern meiosis recombination.Ĭrossover (chiasmata) and the logic of crossover patterning. In addition, frequency of human aneuploidy also shows other age-dependent alterations. Dramatically increased aneuploidy in older women is the well-known "maternal age effect." However, a high frequency of aneuploidy also occurs in young women, derived from crossover maturation inefficiency in human females. A high frequency of human embryos are aneuploid, primarily derived from female meiosis errors. Interestingly, short chromosomes show different crossover patterns compared to long chromosomes. Diverse evidence shows that chromosome axis length determines crossover frequency. Meiotic chromosomes are organized in a loop-axis architecture. Crossover recombination occurs in the context of meiotic chromosomes, and it is tightly integrated with and regulated by meiotic chromosome structure both locally and globally. Aberrant crossover patterns are the leading cause of infertility, miscarriage, and congenital disease. Crossover patterns are tightly controlled and exhibit three characteristics: obligatory crossover, crossover interference, and crossover homeostasis. The critical outcome of meiotic homologous recombination is crossovers, which ensure faithful chromosome segregation and promote genetic diversity of progenies. Repairing DNA double-strand breaks (DSBs) with homologous chromosomes as templates is the hallmark of meiosis. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |