My research is focused on the evolution of developmental genes that encode mutiple isoforms, and the evolution of protein function and regulation. Specifically, I am investigating the evolution of centrosomin, a gene that encodes seven isoforms. Three isoforms are core components of the centrosome, and the maternally supplied cnn1 isoform is required during syncytial development. Based on cnn4 data, the other four isoforms are probably components of the basal bodies of the sperm axoneme and cilia. My research has three major components, which utilize the power of the D. melanogaster toolbox, the parthenogenetic fly D. mercatorum, and varios members of the Arthropoda.

To begin to understand how the cnn gene has evolved, we are sequencing orthologous genes from representatives of the four major arthropod groups. Our lab is currently developing a protocol that we hope will make this process efficient for any gene of interests. With respect to cnn, we would like to know which isoforms were ancestral, and which evolved more recently. From initial data we know that Cnn1, the core centrosomal protein, is evolving rapidly. Was this protein a novel invention that arose during the evolution of syncytial development, or has the protein diverged to function during syncytial development?

To understand the evolution of developmental processes it is critical to understand how proteins function at the molecular level. Based on alignments with a putative ortholog from the moth Bombyx mori, and the best candidate (low similarity) ortholog from the fish Danio rerio, we have identified several conserved functional domains. To analyze the function of these domains in vivo, I am currently generating constructs and transgenic fly lines for rescue experiments with GFP:moth and GFP:fish genes, and a chimeric GFP:moth:fly construct. In addition to the rescue experiments, I am also also using site-directed mutagenesis to generate domain knock-outs in Cnn1, and to activate or inactivate putative phosphorylation sites. All construct will be expressed in D. melanogaster using the GAL4:UAS system.

The animal centrosome is the major microtubule organizing center in most cells. This organelle is required for cell division, organization and cell migration. At the center of the centrosome is a pair of centrioles, which are paternally contributed. If centrioles are always paternally contributed, how do centrosomes form during parthenogenetic development? To address this question we use an automictic thylytokous tychoparthenogenetic fly, D. mercatorum. These flies complete meiosis, produce diploid females via pronuclear fusion, but succed at this process at a very low level. Our initial results demonstrate that these flies form a small pool of free centrosomes prior to the initiation of syncytial development, and that Cnn1 plays a similar essential role. However, each answer has generated many new questions. What is the source of the original centrioles? How do nuclei fuse to produce the zygote? Why is it impossible to select for an improved parthenogenetic rate? How do parthenogentic flies "get around

• Weber, K., Eisman, R., Morey, L., Patty, A., Sparks, J., Tausek, M., Zeng, Z. B.
• (1999).  An analysis of polygenes affecting wing shape on chromosome 3 in Drosophila melanogaster. Genetics 153:2 773-86.
• Weber, K., Eisman, R., Higgins, S., Morey, L., Patty, A., Tausek, M., Zeng, Z. B.
• (2001). An analysis of polygenes affecting wing shape on chromosome 2 in Drosophila melanogaster. Genetics 159:3 1045-57.
• K. Weber*, J. Graves, R. Eisman, J.Harmon and B. Goodwin. (2002). Results of long-term selection experiments with Drosophila. 7th World Congress on Genetics Applied to Livestock Breeding.