435 Biotechnology Building
Professor of Developmental Biology
Kenneth Kemphues is a Professor of Genetics and current Chair of the Department of Molecular Biology & Genetics. He received a B. A. in Biology at the University of Virginia in 1976, and a Ph.D. in Genetics at Indiana University in 1981. He was a National Institutes of Health Postdoctoral Fellow at the University of Colorado from 1981-1984 and joined the Cornell faculty in 1984. His research program focuses on the related questions of embryonic polarity and cell polarity using the nematode C. elegans as a model organism. His research is supported primarily by the National Institutes of Health. Dr. Kemphues teaches Developmental Biology and Developmental Genetics. He is a member of the Genetics Society of America, the Society for Developmental Biology, and is an elected Fellow of the American Association for the Advancement of Science. He is a member of the editorial boards of Development and Molecular Biology of the Cell and serves as an Associate Editor of Genetics.
We are using genetic analysis in the soil nematode Caenorhabditis elegans as a starting point towards understanding the nature and extent of the maternal contribution to early metazoan embryogenesis. The newly fertilized egg of most animals contains within it all of the information required to direct the complex process of embryogenesis. The zygotic nucleus however, is not transcribed until the time of gastrulation. Therefore it is likely that maternal, rather than zygotic, information is responsible for all of the major events of early embryogenesis including establishment of embryonic polarity and the initial steps in the determination of differential embryonic cell fate.
C. elegans' small cell number, simple body plan, rapid development, and known cell lineage combines with its amenability to genetic analysis to make it an ideal organism for this study. Our approach to the problem is in three steps: First, by classical genetic analysis we are identifying and characterizing mutations in genes expressed maternally and required during embryogenesis. Second, using high resolution light microscopy, time lapse video recording, and immunofluorescence microscopy, we are studying the mutant phenotypes to determine what roles are carried out by maternally expressed genes and to assess their relative contribution to embryogenesis as a whole. Our results implicate maternal genes in such diverse roles as meiosis, pronuclear movements, control of cell cycle rates, establishment of polarity, and determination of differential cell fate. Third, we are carrying out molecular, biochemical, and cell biological studies of the products of these genes.
Our major focus for the past several years has been the role of cytoplasmic localization in establishment of embryonic polarity and cell fate determination. In many animals, the determination of cell fates depends upon the proper segregation of factors in the egg cytoplasm prior to or during cleavage. We have identified a set of genes (the par loci) which are required for proper cytoplasmic partitioning in early embryos. Mutations at any of these six loci lead to a maternal effect on the pattern and timing of the early cleavages. In addition, the asymmetric partitioning of germ-line-specific granules is blocked or altered. Our data indicate that these loci define components of a maternally derived system for localization of cytoplasmic constituents during early cleavages, and that failure to localize these constituents results in improper pattern and timing of cleavages, and leads to the ultimate death of the embryos.
More recent information can be found at the Kemphues lab home page
Top panels show wild-type embryos. Bottom panels show par-1 mutant embryos. The left column shows living two-cell stage embryos, the middle column shows two-cell embryos stained with anti-tubulin antibody to visualize mitotic spindles, and the right column shows four-cell embryos stained to show the distribution of germline-specific granules.
Click here for a current list of Dr. Kemphues' publications on PubMed.