Investigating the Mechanism of Sex Determination in Branchinecta lindahli. Michael J. Colgan¹, Janice Krumm¹, Alexis Nagengast². 1) Department of Biology, Widener University, Chester, PA; 2) Department of Biochemistry and Chemistry, Widener University, Chester, PA.

   Establishing the sex of an organism requires the coordination of complex gene pathways via transcriptional and posttranscriptional regulatory mechanisms. Branchinecta lindahli is a freshwater crustacean of the order Anostraca, and members of this order are important biomonitors for their ecosystems as well as a common food stock in the fish industry. A better understanding of their biology has economic and conservation benefits. The genetic sex determination mechanism of B. lindahli is currently unknown. PCR is being performed on B. lindahli cDNA to detect the sex determination gene: doublesex. doublesex has been identified in the closely-related crustacean Daphnia magna (Kato et al. 2011 PLoS Genetics 7(3)). Because doublesex is conserved in the sex determination pathway of D. magna and other related arthropod species, the presence of a doublesex-like gene is also expected in B. lindahli. To identify other genes that influence sex determination, we will hybridize B. lindahli cDNA to Drosophila microarray chips to identify the conservation of genes used in the sex determination pathways between these species. Future work will include sequencing putative doublesex-like genes and determining their activity in B. lindahli sex determination.