Ph.D. Cornell University, 1992
E211 Beadle Center
The long-term goal of our research projects is to understand the molecular basis of gene expression in eukaryotes. Gene activity is influenced by the proteins that package the DNA, by enzymes that modify these proteins or the DNA itself, and by RNA-mediated mechanisms (e.g., RNA interference). All these pathways play important roles in the control of gene expression during organismal development as well as in host defense responses against viruses and transposable elements. Thus, elucidation of these mechanisms will have an impact not only in basic biology but also in medicine and agriculture. We are currently using the unicellular green alga Chlamydomonas reinhardtii and the higher plant Arabidopsis thaliana as model systems to identify and characterize molecular components of the gene silencing machineries. We are also interested in engineering algal strains for the production of biofuels and biomaterials.
RNA Interference (RNAi)
Double-stranded RNA is the trigger at the heart of RNAi and it can induce, in different organisms, a variety of outcomes such as the degradation of homologous RNAs, transcriptional silencing, DNA methylation or even DNA elimination. The RNAi machinery has also been implicated in the processing and function of microRNAs, endogenous small RNAs that regulate gene expression by translational repression or mRNA cleavage. Despite rapid progress in understanding key steps of these pathways, many factors required for RNAi and related mechanisms have not been characterized as yet. We are using a variety of genetic, functional genomics and bioinformatics approaches to identify novel components of the RNAi machinery as well as to examine the role of these pathways in developmental programs and in the biological responses to abiotic stresses.
Algae for biofuels
Algae have important roles in marine, freshwater and terrestrial ecosystems. For instance, 30 to 50% of the planetary net photosynthetic productivity (the difference between photoautotrophic photosynthesis and respiration) is of marine origin and dependent on phytoplankton biomass. Recently, the great potential of algae as feedstocks for renewable biofuel production has also gained recognition. Microalgae are unicellular organisms capable of harnessing sunlight and carbon dioxide to produce high-value chemical compounds, such as lipids and carbohydrates, which can be converted into fuels. Various stress conditions, such as nitrogen deficiency, trigger the accumulation of non-polar lipids (mainly triacylglycerols) in many algal species. Chlamydomonas reinhardtii is one of the best-studied eukaryotic microalgae, with a sequenced nuclear genome, extensive physiological data and a growing toolkit of genetic, genomics and bioinformatics resources. Our objective is to understand the gene regulatory networks that control metabolic pathways of lipid accumulation in Chlamydomonas, with the ultimate goal of engineering algal strains with improved capabilities for renewable biofuel production.