Ion Currents in Microbial Growth and Development
{'Code': '08090100', 'Directorate': {'Abbreviation': 'BIO', 'LongName': 'Direct For Biological Sciences'}, 'Division': {'Abbreviation': 'IOS', 'LongName': 'Division Of Integrative Organismal Systems'}}
{'SignBlockName': 'Kevin Thompson', 'PO_EMAI': 'kthompso@nsf.gov', 'PO_PHON': '7032924220'}
Fungal hyphae, like many other tip-growing organisms, drive electric        currents through themselves such that positive charges enter the apical         zone and leave distally.  Dr. Harold's aim is to discover how these             currents arise and what functions they serve, with particular reference         to their role in the polarization of growth and development.  Hyphae of         the water mold Achlya generate a proton current: protons are apparently         expelled by a H+-ATPase and return into the apical zone by symport with         amino acids.  Recent observations suggest that the flow of electric             charge is not critical for hyphal extension.  However, amino acids must         be continuously present for a tip to extend, and so long as a hypha             grows protons flow into its tip.  Dr. Harold is presently trying to             disentangle the intertwined roles of amino acids in tip extension, in           generating the transcellular proton current and also in chemotropic             growth.  This may help in understanding whether the apical influx of            protons plays a causal role in tip extension or in guiding its progress.        Neurospora, the standard laboratory fungus, also drives a transcellular         electric current of the same polarity, but its ionic composition appears        to differ from that in Achlya.  Tentative evidence suggests that several        ionic species flow into the hyphal trunk, possibly by symport with              protons.  Apical extension, however, seems to require calcium ions and          may be linked to a calcium current.  One possible interpretation is that        calcium ions regulate the exocytosis of apical vesicles and thereby             control tip extension.                                                              Living cells generate electrical currents and potentials by the             active transport of ions across the plasma membrane, and they draw upon         the resulting ion circulations to perform diverse kinds of useful work.         This proposal addresses the hypothesis that transcellular ion currents,         which arise from the spatial segregation of transport systems, play a           significant causal role in complex, intergrated biological processes            such as growth and development.
[{'FirstName': 'Franklin', 'LastName': 'Harold', 'PI_MID_INIT': 'M', 'PI_SUFX_NAME': None, 'PI_FULL_NAME': 'Franklin M Harold', 'EmailAddress': None, 'NSF_ID': '000162850', 'StartDate': '11/01/1987', 'EndDate': None, 'RoleCode': 'Principal Investigator'}, {'FirstName': 'John', 'LastName': 'Caldwell', 'PI_MID_INIT': 'H', 'PI_SUFX_NAME': None, 'PI_FULL_NAME': 'John H Caldwell', 'EmailAddress': 'caldwellj@essex.hsc.colorado.edu', 'NSF_ID': '000245590', 'StartDate': '11/01/1987', 'EndDate': None, 'RoleCode': 'Co-Principal Investigator'}]
{'Name': 'National Jewish Health', 'CityName': 'DENVER', 'ZipCode': '802062761', 'PhoneNumber': '3033981078', 'StreetAddress': '1400 JACKSON ST', 'StreetAddress2': None, 'CountryName': 'United States', 'StateName': 'Colorado', 'StateCode': 'CO', 'CONGRESSDISTRICT': '01', 'CONGRESS_DISTRICT_ORG': 'CO01', 'ORG_UEI_NUM': 'VLQKFEEJ3NE9', 'ORG_LGL_BUS_NAME': 'NATIONAL JEWISH HEALTH', 'ORG_PRNT_UEI_NUM': None}
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{'Code': '1111', 'Text': 'DEVELOPMENTAL SYSTEMS CLUSTER'}
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