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Debashish Bhattacharya Ph.D.

debashish-bhattacharyauiowaedu
http://www.biology.uiowa.edu/debweb/

Professor of Biological Sciences

The field of molecular evolution has as its central goal the resolution of the origins of genes and species. In our lab, we use molecular evolutionary tools to address two major research areas. 1) Endosymbiotic Origin of Plastids and Algal Genomics The algae trace their origins to non-photosynthetic protist lineages that have, via cyanobacterial (primary) or algal (secondary, tertiary) endosymbioses, become the dominant primary producers on our planet. We study the origins of the different algae and their plastids using comparative methods including phylogenetics, high-throughput genomics, bioinformatics, comparative genomics, and organismal biology. Ongoing projects are to generate 10,000 unique expressed sequence tags (ESTs) for a dinoflagellate, a haptophyte, and other algae, to study the origins of red algal-derived secondary plastids in the chromist algae (see photo) and chromalveolate protists. Phylogenetic analysis of plastid and nuclear coding regions allow us to date splits in the eukaryotic tree of life, and in a collaboration with Mariana Oliveira in Sao Paulo, Brazil, we have sequenced the plastid genome of the commercially valuable red alga Gracilaria to gain insights into plastid genome evolution. We have also recently initiated, with a number of collaborators, phylogenetic research to assemble a eukaryotic tree of life. This tree will allow us to understand broad patterns of cellular evolution. 2) Evolution of group I and spliceosomal introns. The nuclear genes of eukaryotes are littered with non-coding sequences called introns. Understanding how introns spread is a fundamental question in biology and forms a major focus of our research. We have recently found a wealth of pre-mRNA (spliceosomal) introns in the nuclear ribosomal RNA (rRNA) genes of Euascomycete fungi, making these organisms ideal for the study of a recent intron invasion into a family of genes that is otherwise generally free of spliceosomal introns. Our analyses suggest that reversal of splicing, mediated by the spliceosome, may facilitate the spread of existing introns into new rRNA sites, with these introns being preferentially inserted into highly conserved, functionally important regions. This reverse-splicing model also offers an explanation for the spread of autocatalytic group I introns, another widespread class of intervening sequences in fungal nuclear rRNA. Spliceosomal and group I introns offer parallel systems with which to test the reverse-splicing model. To do this, we use molecular genetic, biochemical, and phylogenetic methods and primary, secondary, and tertiary structure analyses of rRNAs. These data will ultimately help us approach the long-term goal of understanding the significance of introns to gene and genome evolution. Debashish Bhattacharya lab: http://www.biology.uiowa.edu/debweb/