| Under investigation is the structure and function of the lampbrush chromosomes of the amphibian Xenopus laevis. Three independent lines of investigation are used towards this goal. In one line of experimentation the potential role condensin protein complex in organizing Lampbrush chromatin is investigated. Two distinct condensin complexes are known, and in the oocyte the condensin I members are found in the nucleus to be primarily localized to the cytoplasm, while the condensin II members are primarily nuclear, and shared members are found in both compartments. Surprisingly, the condensin I member XCAP-D2 localizes to the axis despite its low abundance in the nuclear compartment, while the shared condensin component XCAP-E is found primarily in the granular component of the nucleolus.;Next, the role of TRIM family member NF7 on the loops of the lampbrush chromosome is investigated. NF7 is found primarily as a free trimer in the nucleoplasm, and the coiled-coil domain alone was capable of mediating trimerization. Furthermore, trimerization and the presence of the B-box protein domain of NF7 are required for localization of the protein to the loops of the lampbrush chromosome. The accumulation of some mutant NF7 constructs in the Cajal body (CB), when coupled with new data indicating some endogenous NF7 protein localized to the CB, suggests that NF7 may transit through this nuclear body during a functional cycle.;Finally, the mechanism of hnRNP-G recruitment to the lampbrush loops is investigated. Interestingly, the RNA binding domain of the protein is not required for recruitment specificity to the loops. Instead, a poorly characterized portion of the C-terminus of the protein is required for this process. |
