Development of the Genetic Map of Volvox

9300047 Kirk Volvox carteri是一个潜在的强大的模式系统，用于分析分化和发育的遗传学。它是一个真核多细胞有机体，但它只包含两种细胞类型，即永生体细胞和永生生殖细胞，这两种细胞在一个简单的球体内以可预测的模式排列。生物体通常是单倍体，繁殖通常是无性的，突变是明显的表型，但因为很容易诱导有性繁殖，所以正式的遗传分析是可能的。导致组织异常的突变是可行的，因为细胞发育是自主的。由于Volvox的近亲缺乏细胞分化，进化研究的潜力是存在的。这种有机体作为模式系统的一个局限性是缺乏遗传图谱，而且无法对其进行转化。后一种方法是我们实验室最近开发出来的，我们正在进行前一种方法。许多限制性片段长度多态(RFLP)和耐药标记的加入扩大了遗传图谱。已经发展了通过转座子突变来标记和恢复感兴趣基因的方法。未来五年的目标是标记、识别和定位调控生殖细胞和体细胞的发育和分化以及形态发生运动和细胞衰老和程序性细胞死亡的基因。这个项目目标的实现将为研究和理解发育、分化和进化提供一个简单的单细胞生物和更复杂的多细胞生物之间的桥梁。

9300047 Kirk Volvox carteri is a potentially powerful model system for analysis of the genetics of differentiation and development. It is a eukaryotic multicellular organism but it contains only two cell types, mortal somatic cells and immortal germ cells, which are arranged in a predictable pattern within a simple spheroid. The organism is normally haploid, reproduction is usually asexual and mutations are phenotypically obvious but because sexual reproduction is readily induced, formal genetic analysis is possible. Mutations which cause organizational abnormalities are viable because cell development is autonomous. Because there are close relatives of Volvox that lack cellular differentiation, the potential for evolutionary studies exists. One limitation of this organism as a model system has been the lack of a genetic map and an inability to transform it. The latter procedure has been recently developed in our laboratory and we are embarking upon the former. The genetic map has been expanded by the incorporation of many restriction-fragment-length-polymorphism (RFLP) and drug resistance markers. Methods for tagging and recovering genes of interest via transposon mutagenesis have been developed. The goals for the next five years are to tag, identify and map genes that regulate development and differentiation of germ and somatic cells as well as morphogenetic movements and cellular senescence and programmed cell death. %%% The achievement of the goals of this project will provide a bridge organism between simpler single cell organisms and much more complex multicellular organisms for the study and understanding of development and differentiation as well as evolution.