GENETIC ANALYSIS OF MORPHOGENESIS IN A NEMATODE

这项研究的目的是了解基因是如何决定 动物的形态学 一种基因和分子的方法 这个问题是用秀丽隐杆线虫解决的。 C 秀丽线虫是一种适于遗传分析的模式生物， 因为它的固定性， 细胞解剖学和细胞谱系，因为它的序列 基因组正在确定中。 在模型中识别出许多基因 已知诸如秀丽隐杆线虫的生物体在人类中起作用， 癌症和先天缺陷等疾病。 形态学研究 线虫的突变体表明HOX基因决定了 一组连续重复的神经元结构的形态， 射线 HOX基因存在于所有动物中，编码保守的 形成前后体的同源结构域转录因子 轴以及其他结构，如四肢。 HOX基因如何帮助 确定射线的形态将通过研究 野生型和突变体中HOX基因egl-5的表达。 egl-5的调节表达对于特异性表达是必需的。 射线的形态特征。 egl-5的表达将是 通过报告基因、抗体染色和原位RNA测定 杂交方法 将进行新的突变体筛选， 调节EGL-5表达的其它基因。 目的是 理解egl-5表达如何仅限于某些分支 通过识别调节其表达的因子来研究细胞谱系。 另外两个基因的分子特性，它们沿着 EGL-5指定射线身份将通过克隆和 测序

The aim of this research is to understand how genes determine the morphology of animals. A genetic and molecular approach to this problem is taken using the nematode Caenorhabditis elegans. C elegans is a model organism amenable to genetic analysis that is also useful for developmental biological research because of its fixed cellular anatomy and cell lineages, and because the sequence of its genome is being determined. Many genes identified in model organisms such as C elegans are known to play roles in human disorders such as cancer and birth defects. Study of morphological mutants of C elegans has shown that HOX genes determine the morphology of a set of serially-repeated neuronal structures known as rays. HOX genes, present in all animals, encode conserved homeodomain trascription factors that pattern the anteroposterior body axis as well as other structures such as limbs. How HOX genes help to determine the morphology of rays will be determined by studying the expression of one HOX gene, egl-5, in wild type and in mutants. Regulated expression of egl-5 is necessary for specification of the morphological identities of the rays. Expression of egl-5 will be assayed by means of reporter genes, antibody staining, and in situ RNA hybridization. New mutant screens will be carried out to identify additional genes that regulate the expression of egl-5. The aim is to understand how egl-5 expression is confined to only certain branches of a cell lineage by identifying the factors that regulate its expression. The molecular properties of two additional genes that act along with egl-5 to specify ray identities will be determined by cloning and sequencing.