排序方式: 共有24条查询结果,搜索用时 0 毫秒
21.
22.
Kinetochore individualization in meiosis I is required for centromeric cohesin removal in meiosis II
Yulia Gryaznova Leonor Keating Sandra A Touati Damien Cladire Warif El Yakoubi Eulalie Buffin Katja Wassmann 《The EMBO journal》2021,40(7)
Partitioning of the genome in meiosis occurs through two highly specialized cell divisions, named meiosis I and meiosis II. Step‐wise cohesin removal is required for chromosome segregation in meiosis I, and sister chromatid segregation in meiosis II. In meiosis I, mono‐oriented sister kinetochores appear as fused together when examined by high‐resolution confocal microscopy, whereas they are clearly separated in meiosis II, when attachments are bipolar. It has been proposed that bipolar tension applied by the spindle is responsible for the physical separation of sister kinetochores, removal of cohesin protection, and chromatid separation in meiosis II. We show here that this is not the case, and initial separation of sister kinetochores occurs already in anaphase I independently of bipolar spindle forces applied on sister kinetochores, in mouse oocytes. This kinetochore individualization depends on separase cleavage activity. Crucially, without kinetochore individualization in meiosis I, bivalents when present in meiosis II oocytes separate into chromosomes and not sister chromatids. This shows that whether centromeric cohesin is removed or not is determined by the kinetochore structure prior to meiosis II. 相似文献
23.
While food recruitment and foraging have been the subject of many studies, the regulation of the food sharing behaviour remains
poorly understood. In this study, we focused on trophallaxis (or mouth-to-mouth food exchange) within a group of worker ants
as the first step in characterizing food sharing behaviours. In particular, we wanted to investigate the influence of the
type of the food on trophallaxis. We studied three food types: a 1 M sucrose solution, a solution rich in proteins and a 1 M
solution of melezitose, the latter being referred to as the ants’ favourite sugar. Our results show that the type of the food
influences the frequency of trophallaxis but not the duration of each food exchange. Indeed, the total number of trophallaxes
differed with the type of food, whereas the duration of trophallaxis was similar regardless of the food exchanged. Furthermore,
the probability of stopping an exchange per unit of time was constant and did not depend on the time the exchange had already
lasted. This suggests that food distribution is principally regulated by the frequency of trophallaxis rather than the amount
of food exchanged and brings new questions about the regulation of food flow between individuals. 相似文献
24.