David W. Mount. Professor, Department of Molecular and Cellular Biology. Ph.D., University of Toronto. Genetic regulation of the radiation resistance and genetic recombination in the model plant Arabidopsis thaliana; conservation genetics and evolution of rare plant species.

Our main research interest is to discover how plants resist ultraviolet light damage and other types of stress, and to identify the molecular mechanisms which underly this resistance. We are particularly interested in whether or not genetic recombination mechanisms are involved in resistance, as they are in yeast and bacteria. Also, we wish to identify the major genes by cloning and sequencing them and discovering how they are regulated. For example, is there a system of gene induction, similar to the SOS system of E.coli which we have previously studied? To accomplish these goals, we have isolated a set of mutants of Arabidopsis thaliana (so called uvh mutants) which are hypersensitive to UV light. One of these mutants is also hypersensitive to gamma rays and to high growth temperatures, suggesting the mutant gene plays a major role in stress resistance. Two of these plant mutants have already been studied, and we are now prepared to map and clone the genes and to investigate possible regulatory defects, such as alterations in the induction of heat shock or repair proteins. We are also examining these mutants for possible defects in genetic recombination processes, such as T-DNA transformation, and meiotic and mitotic recombination. The laboratory also has considerable expertise in computer analysis of protein and nucleic acid sequences to assist in these studies, and a graduate course is taught on this subject by Dr. Mount.

A second area of research is conservation genetics of rare plants. We are using our experience in molecular genetics and computers to investigate the degree of genetic variation within rare species and between rare and closely related more common species. These studies are designed to learn about the genetic relatedness and evolutionary history of plants, to determine the degree of hybridization and introgression between species, and to try and discover specific genetic determinants in the rare species. The studies are including a RAPD markers (random aplified polymorphic DNA - a PCR analysis of DNA based on using short, random primers), microsatellite DNAs, RFLPs and sequence variations. Finally, we actively participate in an NSF RTG training grant and research group whose theme is Biodiversity, and which provides stipend and research support to graduate students and post-doctoral fellows.

Harlow, G.R., Jenkins, M.E., Pittalwala, T.S. and Mount D.W. 1994. Isolation of uvh1, an Arabidopsis mutant hypersensitive to ultraviolet light and ionizing radiation. Plant Cell 6: 227-235.

Lewis, L.K., Harlow, G.R., Gregg-Jolly, L.A., and Mount, D.W. 1994. Identification of high affinity binding sites for LexA which define new damage-inducible genes in E.scherichia coli. J.Mol.Biol. 241: 507-532.

Sonti, R.V., Chiurazzi, M., Wong, D. Harlow, G.R. Davies, C.S., Mount, D.W. and Signer, E.R. 1995. Deficiency in Agrobacterium T-DNA transformation of radiation sensitive mutants of Arabidopsis thaliana Proc. Natl. Acad. Sci. (USA) 92:11786-11790.

Jenkins, M.E., Harlow, G.R., Shotwell, M.A. and Mount, D.W. 1995. Radiation sensitive mutants of Arabidopsis thaliana Genetics. 140: 725-732.

Jenkins, M.E., Suzuki, T., and Mount, D.W. 1995. A characteristic response of Arabidopsis thaliana to elevated temperatures is mimicked by the uvh6 mutation (submitted to PLANT CELL).

Mount, D.W. 1996. DNA repair: Reprogramming transcription. Nature 383:763-4.

Mount, D.W. 1997. Computer Analysis of Sequences in Molecular Cloning Manual, new edition, by Sambrook et al., published by Cold Spring Harbor Laboratory, Cold Spring Harbor, NY.