Uniparental (UP) inheritance of organellar (mitochondrial and chloroplast) DNA occurs throughout the eukaryotic kingdom, but there is as yet no complete molecular description of its mechanism in any species. UP inheritance of chloroplast chromosomes in the soil alga Chlamydomonas reinhardtii shares a striking feature with mitochondrial DNA inheritance in most animals: the organellar DNA of one parent (the minus mating type in the alga, the male in animals) is specifically destroyed by nuclease activity, meaning that the organellar DNA of the other parent (plus, female) must be protected from the nuclease. This project will evaluate a candidate protector protein, Otu2, and a candidate destroyer, TatD1, in C. reinhardtii as well as two other proteins, Ezy1 and Ezy2, that apparently facilitate their activities in the zygote. Approaches will include immunolocalization and the effects on UP of knocking down and mis-expressing these proteins in gametes and zygotes. Since Otu2 orthologs feature in deubiquination pathways, and TatD1 nucleases with mitochondrial targeting sequences are posited to play a role in apoptosis, these studies may have an impact beyond an understanding of UP.
This project promises to provide long-sought answers to the questions of why organellar (mitochondrial and chloroplast) DNA is only transmitted through one parent, and how this is accomplished. Such understanding is likely to be important to plant and animal breeding programs wherein organellar incompatibilities may contribute to breeding failures. Committed to increasing the public's scientific literacy, the investigator engages extensively in such areas as teacher training and adult education. In addition, she will recruit undergraduate trainees.
