Unequal Cleavage and D Quadrant Specification in the Leech Helobdella

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Embryonic development entails exquisitely orchestrated cell divisions and other processes leading from a single cell, the fertilized egg, to the adult form. Cells arising at each stage of development become fated to make a particular contribution to the next stage via interacting intrinsic factors (inherited from their progenitors) and extrinsic cues (such as signaling molecules produced by neighboring cells). We know that a basic "toolkit" of cellular and molecular mechanisms influencing these "fate decisions" is highly conserved from species to species. Thus, understanding how the toolkit is deployed in various species, including comparatively simple, more easily studied ones such as the leech, can contribute to understanding how diverse kinds of animals evolved their distinct adult body plans, how cell fating processes function in human development and how malfunctions can result in disorders such as cancer and birth defects.This proposal is to study a particular cell division occurring in the 2-cell leech embryo, testing the hypothesis that interactions between intrinsic factors (locally elevated calcium ion concentrations) and extrinsic signals (a highly conserved protein called WNT secreted from the adjacent cell) cause the recipient cell to divide unequally, yielding one daughter cell fated to contribute muscle, nerves and skin to the developing embryo, and another fated to contribute mainly to the gut. Dr. Weisblat's research also provides rigorous and cost-effective training in cell and developmental biology techniques and in the critical skills of analytical thinking and writing for postdoctoral researchers, undergraduate and graduate students, many of whom have gone on to studies in medicine, biotechnology, science policy, teaching and research. In addition to recruiting and mentoring a diverse research group, Dr. Weisblat is director for an NSF REU Site program aimed at improving the recruitment of bioscience students from underrepresented minorities to Ph.D. studies. He has also worked to promote scientific goodwill by teaching in developing nations such as Brazil, Estonia, India, Mexico and Nigeria.