Analysis of factors that control asymmetric division in Volvox carteri

在将受精卵转化为复杂生物体的过程中，最引人注目的壮举之一是产生了许多不同的特化细胞类型，但人们对这一任务是如何实现的还不是很清楚。多细胞绿藻Volvox carteri是一个很好的研究这个问题的生物，因为Volvox的发育非常简单，只有两种不同的细胞类型：大的生殖细胞叫做性腺，小的运动细胞叫做体细胞。glsA（意为“无性腺”）基因对形成性腺的大细胞至关重要，并编码一种蛋白质（glsA），这种蛋白质与人类、大鼠和小鼠的蛋白质密切相关，其积累与细胞分裂/增殖和癌症呈正相关。该实验室最近的研究表明，GlsA与至少两种其他蛋白质（DP和Hsp70A）相关，其中一种（DP）与高等植物和动物中已知的细胞分裂调节因子有关。当前项目的目标是确定这些蛋白质，如GlsA，是否也需要产生两种不同大小和功能的细胞，并确定它们是如何做到的。为了实现这些目标，现有的分子程序将用于：1)产生表达DP和Hsp70A数量减少的Volvox变异；2)克隆额外的基因，编码产生不同大小和命运的细胞所需的因子。预计这些研究将提供对细胞分裂和细胞分化在团藻中耦合的方式的见解，也许也适用于作物植物和人类。此外，完成这些研究的学生将获得成为独立研究人员的宝贵培训。

PI: MillerIOB-0444896AbstractOne of the most remarkable feats to be accomplished during the transformation of a fertilized egg into a complex organism is the production of many different specialized cell types, but precisely how this task is achieved is not well understood. The multicellular green alga Volvox carteri is an excellent organism in which to investigate this issue because Volvox is developmentally very simple, possessing just two different cell types: large reproductive cells called gonidia, and small motile cells called somatic cells. The glsA (for gonidialess) gene is essential for the production of the large cells that become gonidia, and encodes a protein (GlsA) that is closely related to human, rat, and mouse proteins whose accumulation are positively correlated with cell division/proliferation and cancer. Recently work from this lab showed that GlsA associates with at least two other proteins (DP and Hsp70A), one of which (DP) is related to a known regulator of cell division in both higher plants and animals. The goals of the current project are to determine whether these proteins, like GlsA, are also required to produce cells of two different sizes and functions, and to determine how they do so. To accomplish these aims, established molecular procedures will be used to 1) generate Volvox variants that express reduced amounts of DP and Hsp70A and 2) to clone additional genes that encode factors required to produce cells of different sizes and fates. It is anticipated that these studies will provide insights into the manner in which cell division and cell differentiation are coupled in Volvox, and perhaps also in crop plants and humans as well. Furthermore, the students who complete these studies will receive valuable training toward careers as independent researchers.