To study these processes, I use Hydra vulgaris , a member of the evolutionarily ancient phylum Cnidaria, which also includes such animals as sea anemones and jellyfish. There are several advantages to using this animal as a model system for studying developmental processes. First, the animal has a very simple body plan, with radial symmetry about a single axis, so patterning essentially involves only one dimension. Second, hydra has only 6 basic somatic cell types, which are organized into two epithelial layers separated by an extracellular matrix. All the non-epithelial cell types are located in the interstices between the epithelial cells and are referred to as interstitial cells. Third, all the epithelial cells of the body column are continuously mitotic, so tissue is constantly being displaced either up or down the column. This means that patterning processes must be continuously active in the adult animal to maintain the normal body plan, unlike other animals in which the pattern is established early in embryogenesis and remains static after that. Fourth, all the interstitial cell types are continuously produced from a population of multipotent stem cells, so cell fate specification processes are also continuously active. Finally, because of the early divergence of the cnidarians from the main line of metazoan evolution, identification of the genes, molecules and mechanisms utilized by both Hydra and other, more complex animals (such as nematodes, insects and vertebrates) can provide insight into which developmental processes arose early in the evolution of the metazoa and are likely to be fundamental to multicellularity.

To explore the developmental processes described above, my laboratory uses the techniques of molecular biology to isolate and characterize two classes of genes: those encoding transcription factors, especially ones which have been shown to play key roles in development in other systems, and those encoding signaling molecules used for cell-cell communication during development. Once identified and cloned, genes are both characterized at the molecular level and analyzed for function in the animal. Molecular characterization includes such techniques as DNA sequencing, determination of gene copy number by Southern analysis, and the use of gel shift assays and DNA footprinting to analyze the DNA binding sites and cofactor or co-regulator requirements of transcription factors. Functional analysis includes establishing the normal expression pattern of the gene in question by in situ hybridization, examining the effects of cellular and tissue manipulations on its transcription in different cell types and body regions, and deliberate alteration of the normal expression pattern to examine the effects of such mis-expression on the animal.

Like virtually all work in the biological sciences, my research program is a collaborative effort, not only between the members of my lab but also with research groups at other institutions. Currently my major collaborations involve the labs of Dr. H. Shimizu and Dr. T. Fujisawa at the National Institute of Genetics in Mishima, Japan, Dr. S. A. Hoffemeister-Ullerich at the University of Hamburg, Germany, and Dr. J. A. Cassill's group at the University of Texas, San Antonio. Students who are interested in joining my lab are encouraged to read my recent papers to see the types of work currently underway, and to contact me to discuss possible projects. All prospective student researchers must have completed L211, Molecular Biology, or have previous laboratory experience in molecular biology. Completion of L312, Cell Biology, and/or L317, Developmental Biology, would also be helpful but is not required.