GENETICS AND EVOLUTION OF MORPHOLOGY IN DROSOPHILA

描述：在一个非常富有成效的以前的奖项，PI开发了一种媒介， 分辨率图（规模约20厘米）使用QTL来确定遗传 影响男性后叶形状和大小的因素。 的 拟议的研究将进一步解决这一地图的规模为5-10厘米， 已知包含因子的区域。 第二个目标是使用 D内的突变。影响雄性的形态 后叶和创造杂交，以确定是否野生型 这些突变基因的等位基因导致物种差异。 表现出雄性限制性lacZ的增强子-检测器P元件插入 生殖盘中的表达将作为候选基因进行研究。 一 具有性别二态性表达的纯合活插入片段的集合在 手 这些将被筛选性二型致命插入物， 已经鉴定为含有QTL的染色体区域， 种间分析 实验室将对X射线进行镶嵌筛选 在第三条染色体上诱导突变并影响后叶 形态学 这条染色体显示出最大的基因密度 在种间杂交中影响雄性生殖器形态。 一旦在物种中确定了候选基因， 在使用隐性功能丧失突变的杂交测试中评估， 将Mel中的突变体与3个姐妹分类群中的每一个杂交，并将Mel中的突变体与3个姐妹分类群中的每一个进行比较。 结果雄性表型与那些由类似的杂交产生的表型， 野生型蜜环菌 一旦一个候选基因明显与正常的 发展的后叶和在杂交男性的差异，它将是 克隆并根据其转录组织进行表征， 蛋白质序列和表达模式。 P元件介导的转移 其他物种的基因转化为D. melanogaster将提供一个 对该基因在男性生殖器发育中作用的结论性测试。 嵌合基因构建体将用于进一步将基因分配到 负责其影响的功能区域，以解决究竟是什么 序列的各个方面与形态学有关， 物种之间的差异。 基因的多向效应和 还将在混合形态的其它方面上的功能区域 研究了 最终，这将提供有关 基因的进化与自然界中的选择力。

DESCRIPTION: In a very productive previous award, the PI developed a medium resolution map (scale of approximately 20 cm) using QTLs to identify genetic factors affecting the shape and size of the male posterior lobe. The proposed research will further resolve this map to a scale of 5-10 cm in regions already known to contain a factor. A second goal is to use mutations within D. melanogaster that affect the morphology of the male posterior lobe and create hybrids to determine whether the wild- type alleles of those mutant genes contribute to species differences. Enhancer-detector P-element insertions that exhibit male-limited lacZ expression in the genital disc will be studied as candidate genes. A collection of homozygous viable inserts with sex-dimorphic expression is in hand. These will be screened for sexually dimorphic lethal inserts in those chromosomal regions already identified as containing QTLs in the interspecific analysis. The lab will conduct a mosaic screen for X-ray induced mutations on the third chromosome and affecting posterior lobe morphology. This chromosome exhibits the greatest density of genes affecting male genital morphology in interspecific crosses. Once a candidate gene has been identified within the species, it will be assessed in a hybrid test using a recessive loss-of- function mutation, crossing the mutant in mel to each of the 3 sister taxa and comparing the resultant male phenotypes with those produced by similar crosses with wild-type mel. Once a candidate gene has been clearly implicated in normal development of the posterior lobe and in hybrid male differences, it will be cloned and characterized in terms of its transcriptional organization, protein sequence, and pattern of expression. P- element mediated transfer of the gene from other species into D. melanogaster will provide a conclusive test of the role of the gene in male genital development. Chimeric gene constructs will be used to further partition the gene into functional regions responsible for its effects to address exactly what aspects of the sequence are causally involved in the morphological differences between species. The pleotrpic effects of the gene and functional regions on other aspects of hybrid morphologies will also be investigated. Eventually, this should provide information regarding the evolution of genes vis-a-vis the selective forces operating in nature.