IDENTIFICATION OF DEVELOPMENTAL MODULES IN CEPHALOBID NEMATODES

这个子项目是众多研究子项目之一

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Members of the family Cephalobidae (Nematoda: Rhabditida) are non-parasitic microbial-feeding nematodes with cephalic cuticular appendages called probolae. They are nearly ubiquitously distributed in terrestrial ecosystems, yet very little is known of their biology. Probolae are the most important characters used for taxonomic purposes in the group, and their diversity and complexity makes them interesting models for evolutionary questions. They are complex extensions of the extracellular matrix, which adds further importance to understanding their morphology and morphogenesis. Preliminary work done in part at the NCMIR in 2001 suggests that electron tomography would prove invaluable for describing their complex 3D structure, including the relationship between up to seven different protein laminates of which probolae are composed. The work proposed here would contribute to a larger project which aims to formulate and test hypotheses of developmental modules that could be utilized to answer general questions about the origin of novel characters and the evolution of development. It will be combined with phylogenetic, developmental and SEM information in order to address theoretical evolutionary questions and provide a much needed description of anatomy in order to address issues concerning the homology of characters used in phylogenetic analyses and for diagnostic purposes. In addition to helping accomplish these research goals, the tomographic reconstruction will contain information on other sensory and feeding structures of significant interest to developmental geneticists and evolutionary biologists who use nematode models, and the work will serve to evaluate the technique for much broader application in understanding nematode anatomy. Access to a CM300 mid voltage microscope at the University of California, Riverside is already available, which would be used to preview material and to pre-expose sections to the electron beam. Preliminary work showed that contrast was the limiting factor for obtaining images of cuticular structures, so the new energy filtered microscope at the NCMIR would be used for acquiring the final tomographic series.