THREE DIMENSIONAL RECONSTRUCTIONS OF THE CLEAVAGE FURROW

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 胞质分裂始于早期后期，代表有丝分裂的最后阶段，此时两个子细胞通过一种称为脱落的事件而分离。当子细胞通过胞质分裂进行时，它们形成一条分裂沟，在肌动球蛋白收缩环的作用下向内收缩。这形成了一个狭窄的细胞质桥梁，需要分解才能产生两个单独的子细胞。此外，研究表明，成功的胞质分裂和脱落需要回收内小体。不幸的是，卵裂沟内体的机制和功能仍不清楚。已经提出了两个假说，试图解释内体在胞质分裂中的作用。第一种假说是管腔充盈模型，该假说认为沟槽处同步的内小体融合介导子细胞的分裂。第二个假说是传递模型，它提出了内体通过传递内体小泡来调节犁沟处肌动蛋白细胞骨架动力学和/或脂质组成的功能。我们实验室和其他实验室之前的工作已经确立了内小体循环在介导晚期胞质分裂中的作用。Rab11和FIP3已被证明参与了胞质分裂过程中将回收内小体定位到卵裂沟的过程。为了确定Rab11/FIP3相关内切小体在卵裂沟内的时空动力学，我们将使用电子断层扫描技术对卵裂沟进行三维重建。比较末期早期和晚期裂沟断层照片，可以了解末期裂沟中填充了什么细胞器。此外，免疫电子显微镜的使用将为鉴定位于卵裂沟中的细胞器提供依据。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Cytokinesis beginning in early anaphase represents the last stages of mitosis where two daughter cells become separated via an event termed abscission. As the daughter cells progress through cytokinesis they form a cleavage furrow that ingresses by the action of an actomyosin contractile ring. This forms a narrow cytoplasmic bridge that needs to be resolved to produce two separate daughter cells. Additionally, it has been shown that recycling endosomes are required for successful cytokinesis and abscission. Unfortunately, the mechanism and function of endosomes at the cleavage furrow remain unclear. Two hypotheses have been proposed that try to explain the role of endosomes during cytokinesis. The first hypothesis, a luminal filling model, suggests synchronized endosome fusion at the furrow mediates the scission of daughter cells. The second hypothesis, a delivery model, proposes a function for endosomes in the regulation of actin cytoskeleton dynamics and/or lipid composition at the furrow through the delivery of endosomal vesicles. Previous work from our laboratory and others have established a role for recycling endosomes in mediating late stage cytokinesis. Rab11 and FIP3 have been shown to be involved in targeting of recycling endosomes to the cleavage furrow during cytokinesis . To determine the spatiotemporal dynamics of Rab11/FIP3 associated endosomes within the cleavage furrow, we will use electron tomography to three dimensionally reconstruct the cleavage furrow. Comparison of early and late telophase cleavage furrow tomograms will yield a sense of what organelles populate the furrow during telophase. Additionally the use of immunoEM will provide for the identification of organelles populating the cleavage furrow.