Meeting Abstract

P2.90  Saturday, Jan. 5  Finding the Path Between Sperm Chemotaxis and Fertilization Success HUSSAIN, Y.H.*; RIFFELL, J.A.; University of Washington; University of Washington hyasmeen@uw.edu

Reproduction is arguably the most critical point in an organism’s life history, yet many details of this process are still not fully understood. A critical step in fertilization is a sperm’s requirement to locate a conspecific egg while out-competing sperm from other males. This is particularly important for marine invertebrates that broadcast their gametes into the ocean environment, where there is only a short window of time to interact. One mechanism that facilitates gamete interactions is a sperm’s ability to perform chemotaxis to egg-derived compounds, a phenomenon in which sperm orient to an attractant gradient around an egg. However, it is not clear how much chemotactic ability differs in the sperm between males, and whether these differences affect fertilization success. To address these knowledge gaps, we use gametes from the sea urchins Arbacia punctulata and Strongylocentrotus purpuratus, both well-studied models for sperm chemotaxis. Using a microfluidic laminar-flow device, we established a chemical gradient with known chemoattractants and simultaneously imaged sperm motility, orientation, and calcium responses under simulated hydrodynamic conditions. We ran fertilization assays in conjunction with these chemotaxis studies in order to assess the reproductive consequences of the sperm’s response to chemical signals. Preliminary results comparing the motility of males before and after chemoattractant exposure suggest a trend towards significance as well as a large range of motilities within and between individual males. Fertilization assays also show a tentative correlation between these substantially different sperm motilities and the subsequent reproductive outputs, suggesting that differing responses to the same chemoattractive stimulus may influence reproductive success.