Jahn 9319009 The proposed experiments aim to understand how chromatin structural changes influence in DNA rearrangements during macronuclear development and include the following. The timing of replication, transcription and appearance of major histone and non-histone proteins will be determined by labeling studies. Chromatin proteins whose synthesis and deposition in the developing macronucleus correlate with excision will be identified. Relationships to Tec excision will be determined by nuclease digestion to identify alterations in the Tec element chromatin structure. The extrachromosomal circular forms of Tec elements will be purified as chromatin to determine whether proteins involved in excision remain associated. Specific non-nucleosomal protein interactions will be further identified by footprinting. %%% Ciliated protozoa contain two types of nuclei, the micronucleus which serves as a transcriptionally inert germline nucleus and the macronucleus which transcriptionally directs cell functions. A variety of DNA rearrangements and DNA processing events are involved in the formation of the macronuclear genome from the micronuclear genome during the sexual phase of the ciliate life cycle. This project has as its goal an understanding of how chromatin structural changes influence the DNA rearrangements during macronuclear development. ***
