The Fast Block to Polyspermy
{'Code': '08090100', 'Directorate': {'Abbreviation': 'BIO', 'LongName': 'Direct For Biological Sciences'}, 'Division': {'Abbreviation': 'IOS', 'LongName': 'Division Of Integrative Organismal Systems'}}
{'SignBlockName': 'Judith Plesset', 'PO_EMAI': None, 'PO_PHON': None}
Polyspermic eggs usually die after a short period of abnormal                   embryogenesis, but eggs of many animals and at least two plants                 are protected from polyspermy by "fast" and "slow" blocks.  The                 studies proposed here will extend out general understanding of                  the fast block (a transient, ion-mediated blockage) using fucoid                algae as a model system.  Physiological and electrophysiological                techniques will be used to describe the ionic dependence of the                 fast block and the fertilization potential.  The effect of the                  sperm/egg ratio on polyspermy will be evaluated in several fucoid               species, and data on fertilization and sperm/egg rations in the                 field will be collected.  Natural levels of polyspermy will be                  determined by placing tiles within appropriate portions of the                  intertidal zone and observing the development of colonizing                     zygotes.  Such studies will examine the possibility that                        recruitment of zygotes is affected by failure of the fast block                 during periods of natural osmotic stress.  Little information is                available on polyspermic blocks in plants.  The proposed work                   will make a significant contribution in this area, both through                 the proposed studies of fucoid algae and by examining several                   other marine and freshwater algae for the presence of an ionic                  block to polyspermy.                                                            %%%                                                                             Eggs that are fertilized by more than one sperm usually die after               a short period of abnormal embryogenesis.  In many organisms                    polyspermy is prevented by two successive mechanisms- a fast                    acting block and a slower one.  The fast block is mediated by                   transient ionic fluxes that begin immediately after the first                   fertilization.  In spite of its widespread occurrence, there is                 little ecological data available to evaluate the importance of                  this fast block under natural circumstances as opposed to in the                laboratory where ionic conditions are manipulated or sperm/egg                  ratios are high.  Dr. Brawley proposes to investigate the                       natural situation using fucoid algae in tide pools where ionic                  conditions can vary dramatically. She will thus obtain ecological               data that are currently lacking on natural sperm/egg                            concentrations, and an evaluation of how common polyspermy is in                nature.
{'FirstName': 'Susan', 'LastName': 'Brawley', 'PI_MID_INIT': 'H', 'PI_SUFX_NAME': None, 'PI_FULL_NAME': 'Susan H Brawley', 'EmailAddress': 'brawley@maine.edu', 'NSF_ID': '000250859', 'StartDate': '09/01/1988', 'EndDate': None, 'RoleCode': 'Principal Investigator'}
{'Name': 'Vanderbilt University', 'CityName': 'NASHVILLE', 'ZipCode': '372032416', 'PhoneNumber': '6153222631', 'StreetAddress': '110 21ST AVE S', 'StreetAddress2': None, 'CountryName': 'United States', 'StateName': 'Tennessee', 'StateCode': 'TN', 'CONGRESSDISTRICT': '05', 'CONGRESS_DISTRICT_ORG': 'TN05', 'ORG_UEI_NUM': 'GTNBNWXJ12D5', 'ORG_LGL_BUS_NAME': 'VANDERBILT UNIVERSITY', 'ORG_PRNT_UEI_NUM': None}
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{'Code': '1111', 'Text': 'DEVELOPMENTAL SYSTEMS CLUSTER'}
{'url': 'https://www.nsf.gov/awardsearch/download?DownloadFileName=1988&All=true', 'xml': '8802065.xml'}