Research Interests
My research is aimed at answering this question: How do living things tell time? I am interested in circadian rhythms, the daily activity cycles driven by internal clocks in all eukaryotes and some prokaryotes. The goal of my research is to describe the mechanism of a circadian clock at the molecular and biochemical level. Because circadian rhythmicity is a fundamental property of all eukaryotic cells, an understanding of the mechanism of rhythmicity will give us important insights into how cells function.
I work with the filamentous fungus Neurospora crassa, a model organism that is at the forefront of circadian rhythm research. We use the rhythm of spore-formation (conidiation) as a visible marker for the state of the internal clock. Previous research has shown that the FRQ, WC-1 and WC-2 proteins are important for rhythmicity in Neurospora, but our understanding of how the circadian clock functions must be incomplete because conidiation rhythms can continue in the absence of functional FRQ and WC genes. I am interested in finding the oscillator that drives rhythmicity in the absence of FRQ (the FRQ-less oscillator, or FLO).
I have found conditions that favor the expression of FRQ-less rhythms, and my lab has used these conditions as tools to assay the functioning of the FLO. Our current goal is to identify the components of the FLO, determine how they interact to produce an oscillator mechanism, and determine how that oscillator interacts with the FRQ/WCC oscillator.
My lab’s strategy is to search for genes that affect the FLO, by using standard genetics to introduce known clock mutations into FRQ-less strains, and by mutagenesis to create new mutations affecting FLO. We identified several mutations that disrupt FLO and our mapping and functional analyses of the genes revealed the surprising finding that they all code for protein components of the TOR (Target of Rapamycin) signalling pathway. The TOR pathway transmits nutrient information and stress signals to the cellular machinery that leads to either growth or stress responses. We are now studying these TOR pathway proteins to discover where the proteins are located in the cell and what proteins they interact with. We are also looking at the effects of our FLO-affecting mutations on the function of the FRQ/WC oscillator and on biochemical rhythms.
Projects Available
Graduate and undergraduate student projects are available. Some potential topics and methods include:
- Using standard genetics techniques to construct double-mutant fungal strains to assay the interactions between different clock-affecting mutations
- Using genetic engineering techniques to construct fungal strains carrying altered clock-affecting genes
- Using immunoblotting, qRT-PCR and Northern blotting to look at rhythmicity of clock-controlled proteins and their RNAs
- Using fluorescence microscopy of fluorescent protein-tagged strains to look at the subcellular localization of proteins
- Using co-immunoprecipitation to look at protein-protein interactions
- Using time-lapse photography to assay rhythms in spore formation
