Use of the Homeobox System to Elucidate Metazoan Sister-Group Relationships

Drs。巴斯和鲁德尔提议发起一项研究计划，旨在解决后生动物门的问题。后生动物系统发育的现状是相当不确定的，形态学和分子数据集支持相互矛盾的假设。他们认为，对antp类同源盒基因的检查将证明能够解决主要的不确定性。同源盒序列的极端保守性及其独特的基因组组织模式为更高水平的系统发育分析提供了丰富的理想特征。在本研究中，他们将通过对甲壳类、螯足类、蛛形纲、软体动物、爪足类和环节动物的基因组多样性、组织和同源盒序列的描述，重新审视环节动物和节肢动物之间的关系。结合刺胞动物、线虫、单胞动物、棘皮动物和脊索动物中不断增长的同巢箱数据库，这项工作不仅有望解决环节动物-节肢动物的关系，而且还有望揭示最具物种的原口动物和后口动物门内部和之间的关系。同源盒系统用于系统发育分析尤其引人注目，因为这些基因已被证明是参与早期胚胎模式形成和细胞命运规范的调节网络的核心组成部分。因此，随着我们对发育的分子遗传学的理解的增长，在这项研究的进展中产生的信息很可能将允许研究发育新颖性的起源。要实现这些目标，就需要发育遗传学家和进化生物学家的合作。

Drs. Buss and Ruddle propose to initiate a research program directed at the resolution of the metazoan phyla. The current state of metazoan phylogeny is one of considerable uncertainty, with morphological and molecular data sets supporting conflicting hypotheses. They suggest that examination of Antp-class homeobox genes will prove capable of resolving the principle uncertainties. The extreme conservation of sequence of homeoboxes and their distinctive pattern of genomic organization provide an abundance of characters ideal for higher level phylogenetic analysis. In this proposal, they will re-examine the relationship between annelids and arthropods by characterization of the genomic diversity, organization, and sequences of homeoboxes from crustaceans, chelicerates, arachnids, molluscs, onychophorans, and annelids. Combined with the growing existing database on homeoboxes in cnidarians, nematodes, uniramians, echinoderms and chordates, this work holds the realistic promise of resolving not only the annelid-arthropod relationship, but also of shedding light on the relationships within and between the most speciose protostome and deuterostome phyla. The use of the homeobox system for phylogenetic analysis is particularly compelling because these genes have proved to be central components of the regulatory networks involved in early embryonic pattern formation and specification of cell fate. Thus, as our understanding of the molecular genetics of development grows, it is likely that the information generated in the progress of this research will permit study of the origin of the developmental novelty. To accomplish these goals it will require the collaboration of developmental geneticists and evolutionary biologists.