Molecular evolution of developmental regulatory pathways

在动物的发育过程中，许多细胞和细胞类型（包括干细胞）会选择何时何地改变它们的“命运”。这些决定是由作用于细胞（外部或外在因素）和细胞内（内在因素）的分子途径控制的。这些“信号转导”途径对于理解这些细胞选择至关重要。幸运的是，即使在原始动物中，这些通路中的分子也非常相似，这使得我们可以使用简单的动物“模型”进行这些研究。在这个提议中，我们想做一些实验，让我们了解是什么让这些分子途径改变和进化，这样不同的动物就有了不同的特征。我们将使用一种简单的动物，土壤线虫，来研究控制一个简单选择的分子，即雄性和雌性的命运。我们已经证明，在两个相关的隐杆线虫物种（秀丽隐杆线虫和秀丽隐杆线虫）中，相同的分子以不同的方式控制这种选择。在一个物种中，我们已经确定了许多相关因素，而在另一个物种中，我们还没有。我们选择的动物模型允许我们使用许多不同的方法（遗传学，分子生物学，基因组学和细胞生物学）。拟议的分析将i)使用正向和反向遗传学来评估性别决定蛋白的各自作用；ii)利用遗传学鉴定和描述新的性别决定位点（特别是那些控制精子/卵母细胞开关的位点）；iii)测试这些新基因的秀丽隐杆线虫同源物，以寻找在性别决定中以前未被认识到的作用；iv)结合这两个物种的分析结果（加上之前其他物种的数据），开始对这些因素进行结构-功能分析。这一分析结果将有助于解决发育生物学中的两个重要问题。首先，（也是最具体的）秀丽隐杆线虫的性别决定调控体系是如何在分子水平上起作用的？第二（一般来说）发育调控途径是如何进化的？

During development of animals, many cells and cell types (including stem cells) make choices as to when and where to change their 'fate'.  These decisions are controlled by pathways of molecules that act both on the cell (outside or extrinsic factors) and inside the cell (intrinsic).  These 'signal transduction' pathways are critically important for understanding these cellular choices.  Fortunately, the molecules in these pathways are often very similar in even primitive animals, allowing us to use simple animal 'models' for these studies.  In this proposal, we want to do experiments that will allow us to understand what allows these molecular pathways to change and evolve, so that different animals have different characteristics from one another.  We will be using a simple animal, the soil nematode Caenorhabditis, examining the molecules that control a simple choice, that between male and female fates.  We have already shown that in two related Caenorhabditis species (elegans and briggsae), that the same molecules act in different ways to control this choice.  In one species, we have identified many of the relevant factors, while in the second, we have not.  The animal model that we have chosen allows us to use many different approaches (genetics, molecular biology, genomics and cell biology).   The proposed analysis will i) use forward and reverse genetics to assess the respective roles of the sex determining proteins; ii) Use genetics to identify and characterize novel sex- determination loci (particularly those controlling the sperm/oocyte switch); iii) test the C. elegans homologues of these novel genes for any previously unrecognized role in sex determination; and iv) combine the results from these analyses in the two species (plus previous data from other species) to begin a structure-function analysis of the factors.  The results of this analysis will help to address two important questions in developmental biology.  First, (and most specifically) how does the C. elegans sex determination regulatory hierarchy work at the molecular level?  Second (and generally) how do developmental regulatory pathways evolve?