The green alga Volvox carteri possesses just two cell types and is an excellent model for the study of cellular differentiation mechanisms and their evolution. Currently there are only two selectable markers available for introducing genes into V. carteri to study their function. To create a new selectable marker for V. carteri transformation, a chlorate-resistant nitrate reductase gene (CR-nitA), has been synthesized. Nitrate reductase reduces nitrate to nitrite and, similarly, chlorate to chlorite, which is toxic to cells. Previous studies have demonstrated that a cysteine to alanine change in a conserved amino acid in nitrate reductase yields an enzyme that dimerizes but does not retain enzymatic activity. The CP-nitA marker gene encodes a product with an analogous c139a mutation and is driven by a high expression promoter so that transformants that take it up should over-express non-functional CP-NitA protein that dimerizes with wild type nitrate reductase. This should titrate functional nitrate reductase protein and permit transformants to survive chlorate. I am using gene assembly and subcloning to synthesize a Volvox CP-nitA gene with a constitutive Hsp70-Rubisco-gene promoter and an HA-epitope tag. I will test the completed construct for chlorate resistance following transformation into V. carteri.

Qian received her Ph.D. in August, 2005 and is now a postdoctoral fellow in the laboratory of Dr. Jiandong Cheng at the H. Lee Moffitt Cancer Center & Research Institute in Tampa, Florida. Currently she is investigating the E3 ligase that targets the tumor suppressor protein p53.

Kori is currently a first-year student in the Medical Scientist Training Program at UT Southwestern Medical Center in Dallas, Texas.

Stephanie is the recipient of a 2006 NIH Post-Baccalaurate Intramural Resarch Training Award (IRTA) and is currently a trainee in this program.

Eric is currently a second-year Ph.D. student in the department of Molecular and Cell Biology at the University of Maryland, Baltimore, in the laboratoryof Dr. Stuart Martin, where he is studying the role of cytoskeltal factors in breast cancer metastasis.