Evolution of Dimorphic Sex Chromosomes
{'Code': '08010207', 'Directorate': {'Abbreviation': 'BIO', 'LongName': 'Direct For Biological Sciences'}, 'Division': {'Abbreviation': 'DEB', 'LongName': 'Division Of Environmental Biology'}}
{'SignBlockName': 'Tarri Joyner', 'PO_EMAI': 'tjoyner@nsf.gov', 'PO_PHON': '7032927742'}
The proposed research will experimentally test predictions                 from recent theory, concerning the mechanisms that lead to the                  evolution of dimorphic sex chromosomes.  Most animal species, and               a smaller percentage of plant species, have a special pair of                   chromosomes, the X and Y sex chromosomes, that determine gender.                The typical pattern is for males to carry two types of sex                      chromosomes, and X and a Y, and for females to carry two of the                 same type (X) of sex chromosome.  Several lines of evidence now                 indicate that sex chromosomes are derived from a pair of                        chromosomes which formerly were not associated with the                         determination of gender.  This transition first involves the                    evolution of a major sex determining gene, followed by the                      evolution of a sex-determining chromosomal segment, and finally                 in the evolution of sex-determining chromosomes.  During the                    evolution of sex chromosomes, one chromosome, the X, evolves                    enhanced biochemical activity (dosage compensation) while the                   partner chromosome, the Y, is degraded and loses virtually all                  genetic activity.  The sex chromosomes also lose their ability to               exchange genetic material during this transition.  An                           understanding of the genetic mechanisms responsible for the                     formation of sex chromosomes is the focus of the proposed                       research.  The investigator will use a Drosophila melanogaster                  (common fruit fly) model system to experimentally create a new                  pair of sex- determining genes and chromosomes.  The investigator               will then use this model system to explore the mechanisms that                  lead to the breakdown in genetic exchange between the sex                       chromosomes, and to the mechanisms that lead to the deterioration               (accumulation of mutations) of the genetic activity of the Y sex                chromosome.                                                                          An understanding of the evolution of dimorphic sex                         chromosomes has many practical applications.  First, the presence               of sex chromosomes causes males (more generally the heterogametic               sex) to be far more susceptible to hereditary disease.  Dimorphic               sex chromosomes are the physical basis for sex-linked inheritance               and cause males to inherit many hereditary diseases thousands of                times more frequently than females.  The evolution of dimorphic                 sex chromosomes also results in the phenomena of dosage                         compensation (a modified level of gene expression for the                       hereditary material located on the sex chromosomes).  Biochemical               irregularities with dosage compensation are responsible for some                forms of hereditary disease.  The proposed experiments will also                monitor the accumulation of deleterious mutations on both the sex               chromosomes and on ordinary chromosomes.  An understanding of                   this accumulation process is important in understanding the risk                to human populations of increasing levels of exposure to                        radiation (e.g. that produced from nuclear waste and the thinning               of the ozone layer of the atmosphere).  Recent applied                          theoretical work by the investigator also suggests that data from               the experiments will be useful in determining the genetic risk                  (due to inbreeding depression and natural levels of background                  radiation) to wildlife populations that are maintained to small                 effective population size, such as occurs in parks and game                     refuges.
{'FirstName': 'William', 'LastName': 'Rice', 'PI_MID_INIT': 'R', 'PI_SUFX_NAME': None, 'PI_FULL_NAME': 'William R Rice', 'EmailAddress': 'rice@lifesci.ucsb.edu', 'NSF_ID': '000271799', 'StartDate': '05/01/1989', 'EndDate': None, 'RoleCode': 'Principal Investigator'}
{'Name': 'University of New Mexico', 'CityName': 'ALBUQUERQUE', 'ZipCode': '87131', 'PhoneNumber': '5052774186', 'StreetAddress': '1700 LOMAS BLVD NE STE 2200', 'StreetAddress2': None, 'CountryName': 'United States', 'StateName': 'New Mexico', 'StateCode': 'NM', 'CONGRESSDISTRICT': '01', 'CONGRESS_DISTRICT_ORG': 'NM01', 'ORG_UEI_NUM': 'F6XLTRUQJEN4', 'ORG_LGL_BUS_NAME': 'UNIVERSITY OF NEW MEXICO', 'ORG_PRNT_UEI_NUM': None}
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{'Code': '112700', 'Text': 'Evolutionary Processes'}
{'url': 'https://www.nsf.gov/awardsearch/download?DownloadFileName=1988&All=true', 'xml': '8818714.xml'}