9414416 Klobutcher The molecular mechanisms involved in DNA rearrangement processes of eukaryotic organisms are, in many instances, poorly understood. This laboratory has been studying the extensive genome reorganization that occurs in hypotrichous ciliated protozoan Euplotes crassus. During its life cycle, this organism transforms a copy of its chromosomal micronucleus into a macronucleus that contains only short linear, gene-sized DNA molecules. On the order of 100,000 interstitial segments of DNA are deleted during this process, including short elements(internal eliminated sequences; IESs) and highly repetitive, transposon-like elements. Differential screening approaches will be used to isolate genes and proteins that are expressed specifically during macronuclear development. The developmental cDNA library will also be expressed and screened using segments of DNA that undergo rearrangement as probes in an attempt to directly identify clones that encode proteins that interact with rearrangement sites. The isolated genes will be analyzed in regard to time of developmental expression and studies will be done to determine if their gene products localize to the developing macronucleus. Such genes, if found, will be completely sequenced to gain further insight into their function. %%% DNA rearrangement is used as a means of constructing functional protein coding regions and thus can be viewed as a means of developmentally regulating gene expression. To learn about such processes in a eukaryotic organism, this laboratory has been, and will continue, to study the extensive genome reorganization that occurs in the hypotrichous ciliated protozoan, Euplotes crassus. Studies in this area will include determining which of the multiple nuclei in a cell undergoing macronulear development is responsible for producing developmentally regulated transcripts and examining developmental-specific genes for shared sequence elements that are potentially involved in their coordinate regulation. ***
