Genes encoding proteins involved in cell division may play additional roles in development

• Jessica Benito, Biological Sciences, University of Delaware

• Jia Song, Biological Sciences, University of Delaware

Several genes that are known to play a crucial role in mitosis may have alternative functions in embryogenesis. To test this hypothesis, we examine the spatial and temporal localization of the RNAs involved in mitosis throughout various stages of development. The group of genes we examined include those that encode for motor proteins, cytoskeletal elements and their modulators, vesicular transport, and cell cycle regulators. Results indicate that transcripts encoding motor proteins, such as Dynein and CENP-E are expressed in the tripartite gut of gastrulae and in the endomesodermal area of the blastulae. Rab11 and Ran, small GTPases, are expressed in the endomesoderm of the blastulae and in the gut of the gastrulae as well as in the cardiac sphincter. Staufen was enriched in the endomesoderm, fore- and hindgut, apical domain, and in the arms of the larvae. Cytoskeleton elements, Tubulin α1 and β-actin, are expressed in the ectoderm, as well as the mid- and hindgut of gastrulae and larvae. The transcripts of genes involved in the cell cycle progression, Aurora B, APC, Cyclin B, CDK1, and Polo Like Kinase 1 (PLK1) have various localization patterns that include different parts of the gut in the gastrula and larval stages and patchy endodermal expression in the blastula stage. Results from the cell proliferation assay show that not all cells expressing transcripts related to the cell cycle are actively undergoing mitosis. Results from the use of inhibitors of PLK1 and CDK1 indicate that these proteins play important roles in gut development. These results support the idea that these genes may have novel functions in addition to their functions in cell proliferation.