Molecular Evolution of the Synaptonemal Complex in the genus Drosophila. Lucas Hemmer, Justin Blumenstiel. Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS.

   The synaptonemal complex (SC) is a highly conserved meiotic structure seen across eukaryotes that functions to hold the homologs together during meiosis and facilitate exchange. Three Drosophila-exclusive proteins have been identified as the components: C(3)G, C(2)M and Cona. Each protein is necessary for proper meiotic function; mutations lead to reduced crossing over and chromosomal non-disjunction. Despite the conserved nature of the SC and the key role that these three proteins have in meiosis, they display little apparent sequence conservation. We are performing a molecular evolution analysis to determine the nature of selection that might explain this lack of apparent conservation. To perform this analysis, we searched 23 genomes across the Drosophila genus using tblastn and the D. melanogaster protein sequences as our query. Several species of Drosophila have no recognizable sequences corresponding to these crucial SC components. With the recognizable hits, the sequences were aligned using translation MAFFT and MUSCLE and analyzed by Branch-site REL and GA Branch for evolutionary rates. Preliminary studies have demonstrated that the components of the SC are evolving with very little constraint and with very little adaptation, leaving questions as to how such essential proteins are undergoing such high rates of evolution.