A predominant line of research in the Byers lab concerns the integration of mitotic spindle behavior with other aspects of the yeast cell cycle. Mutations that alter the formation and regulation of spindle pole body -- the organelle that plays a key role as the nucleation center for spindle microtubule assembly -- lead to identifiable changes in subcellular structure. Detailed analysis of these changes by immunocytochemical and electron microscope methods reveal phenotypic characteristics that provide a framework for isolating yet other mutations affecting important components of the cell cycle mechanism. Functions of current interest include those that mediate the formation of a new spindle pole body at the beginning of the cell cycle or control separation of the newly formed spindle pole from the parental one so that the spindle can form. Other genes under study serve to maintain integrity of the mitotic spindle during the anaphase movements. Key methods include cloning of the relevant genes, sequencing and deletion analysis, and creation of immunological tools (such as epitope-tagged alleles) for cytological studies.
Other research in the lab focuses on the mechanisms that mediate synapsis and recombination between homologous yeast chromosomes in prophase of meiosis. The protein encoded by the HOP1 (for homologue pairing) gene has been found to play a crucial role in assembly of the synaptonemal complex, an organelle that is highly conserved among eukaryotes. Other genes of interest coordinate the complex array of meiotic functions, some of them acting as "checkpoints' to ensure appropriate rates of progression through successive stages of the overall process.
McDonald HB and Breck Byers. 1997. A proteasome cap subunit required for spindle pole body duplication in yeast. J Cell Biol 137:539-553.
Kironmai KM, Muniyappa K, Friedman DB, Hollingsworth NM, and Breck Byers. 1998. DNA-binding activities of Hop1 protein, a synaptonemal complex component of Saccharomyces cerevisiae. Mol Cell Biol 18:1424-1435.
Dirick L, Goetsch L, Ammerer G, and Breck Byers. 1998. Regulation of meiotic S phase by Ime2 and a Clb5,6-associated kinase in Saccharomyces cerevisiae. Science 281:1854-1857.
Mathias N, Johnson S, Breck Byers, Goebl M. Mar. 1999. The abundance of cell cycle regulatory protein Cdc4p is controlled by interactions between its f box and Skp1p. Mol.Cell Biol. 19(3):1759-67
Munoz-Centeno MC, McBratney S, Monterrosa A, Breck Byers, Mann C, Winey M. July 1999. Saccharomyces cerevisiae MPS2 encodes a membrane protein localized at the spindle pole body and the nuclear envelope. Mol Biol Cell. 10(7):2393-406.
Muniyappa, K., S. Anuradha, and Breck Byers. 2000. Yeast meiosis-specific protein Hop1 binds to G4 DNA and promotes its formation. Mol. Cell. Biol. 20: 1361-1369.
Comai, L., A.P. Tyagi, K. Winter, R. Holmes-Davis, S.H. Reynolds, Y. Stevens, and B. Byers. 2000. Phenotypic instability and rapid gene silencing in newly formed Arabidopsis allotetraploids. The Plant Cell. 12: 1551-1567.
Zheng, C.-J., S.-W. Guo, and B. Byers. 2000. Modeling the maternal-age dependency of reproductive failure and genetic fitness. Evolution and Development. 2: 203-207