Modulation of Embryonic Metabolism and Growth by Urea
{'Code': '08090300', 'Directorate': {'Abbreviation': 'BIO', 'LongName': 'Direct For Biological Sciences'}, 'Division': {'Abbreviation': 'IOS', 'LongName': 'Division Of Integrative Organismal Systems'}}
{'SignBlockName': 'Bruce L. Umminger'}
This is a proposal to investigate the physiological mechanism                   that links the metabolism and growth of embryonic turtles to the                water exchanges occurring between their eggs and the environment.               Embryonic turtles form large quantities of urea as the end-                     product in protein catabolism, and this urea accumulates in all                 fluid compartments inside their eggs over the course of                         incubation.  The rate of increase in concentration of urea is                   higher among eggs in negative water balance (i.e., in dry                       environments), but the rates of metabolism and growth by embryos                are lower in the former than in the latter.  Research described                 here will focus on the possibility that urea, which is known to                 inhibit key metabolic enzymes at low concentrations in vitro,                   plays, a critical role in suppressing metabolism in embryos with                access to limited supplies of water.  A pair of experiments will                determine (1) whether manipulating concentration of urea inside                 eggs affects the size of hatchling turtles, and (2) whether the                 effect of urea is mediated by a suppression of embryonic                        metabolism and growth.  These experiments comprise an important                 test for a novel theory purporting to explain why animals                       regulate the osmotic and ionic composition of their body fluids.                The research will also elucidate an ecologically important                      mechanism whereby embryonic turtles balance their demand for                    water with availability of water.  Many species of turtles                      produce flexible-shelled eggs that exchange water relatively                    freely with the environment inside their subterranean nests.                    Eggs incubating in moist environments consequently absorb large                 amounts of water during development, whereas eggs incubating in                 relatively dry settings lose water to their surroundings.                       Interestingly, embryos developing in moist environments (and                    having access to relatively large quantities of water) have                     higher rates of metabolism and growth than embryos developing in                dry conditions (and having access to smaller amounts of water).                 Research to be performed under auspices of this grant will ask                  how the availability of water to developing embryos affects their               metabolic waste, differs in concentration in blood and other body               fluids from embryonic turtles developing wet and dry                            environments, and that high concentrations of urea cause and                    inhibition of metabolism and growth.
{'FirstName': 'Gary', 'LastName': 'Packard', 'EmailAddress': 'packard@lamar.colostate.edu', 'StartDate': '02/15/1989', 'EndDate': None, 'RoleCode': 'Principal Investigator'}
{'Name': 'Colorado State University', 'CityName': 'Fort Collins', 'ZipCode': '805232002', 'PhoneNumber': '9704916355', 'StreetAddress': '601 S Howes St', 'CountryName': 'United States', 'StateName': 'Colorado', 'StateCode': 'CO'}
[{'Code': '1141', 'Text': 'PHYSIOLOG & STRUCTURAL SYS'}, {'Code': '9145', 'Text': 'SPECIAL PROGRAMS-RESERVE'}]
{'url': 'https://www.nsf.gov/awardsearch/download?DownloadFileName=1988&All=true', 'xml': '8816123.xml'}