| NSF Org: |
EAR Division Of Earth Sciences |
| Recipient: |
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| Initial Amendment Date: | September 3, 2004 |
| Latest Amendment Date: | September 3, 2004 |
| Award Number: | 0416194 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Robin Reichlin
EAR Division Of Earth Sciences GEO Directorate for Geosciences |
| Start Date: | October 1, 2004 |
| End Date: | September 30, 2005 (Estimated) |
| Total Intended Award Amount: | $65,510.00 |
| Total Awarded Amount to Date: | $65,510.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
1850 RESEARCH PARK DR STE 300 DAVIS CA US 95618-6153 (530)754-7700 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
1850 RESEARCH PARK DR STE 300 DAVIS CA US 95618-6153 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): |
OPPORTUNITIES FOR RESEARCH CMG, MATHEMATICAL GEOSCIENCES |
| Primary Program Source: |
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| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
Horizontal gene transfer among microorganisms is a critical process
that impacts bacterial evolution over long time horizons as well as
the spread of traits such as antibiotic resistance on short time
scales. Recently there has been heightened public concern about the
risk of gene transfer from genetically engineered organisms to
indigenous organisms and its consequences. Many environmental
microorganisms spend a large part of their viable life cycle in the
porous medium of the natural subsurface, such as soils and aquifer
materials. Because it is a natural filter for water the subsurface
also provides a mixing zone for different strains of bacteria, that
each partition between the aqueous and solid phases. Thus to
understand the ramifications of horizontal gene transfer in the
natural environment, it is important to study the interactions
between different species as they undergo fate and transport in
porous media. The primary goal of this project is to evaluate the
kinetics of microbial attachment-detachment to porous media solid
surfaces, and the coupled kinetics of horizontal gene transfer in
porous media via conjugation. The green fluorescent protein (GFP)
gene expression system will be used with known hosts and recipients
originally isolated from soils to quantify rates of conjugative gene
transfer in controlled micromodel experiments. The gene transfer is
expected to be limited by the paired residence time of host and
recipient cells together on solid surfaces, and so the distributions
of these paired residence times and the distribution of gene transfer
times will be compiled from the micromodel experiments. The model
for these data will be crafted by combining a biased Levy motion with
drift for the bacterial transport in the porous media, with an
alpha-stable random variable for residence time attached to surfaces,
with a non-Markovian reaction kinetic model for the gene transfer
from host to recipient. The intellectual merit of this project
arises from the coordinated collaboration of people with expertise in
hydrology, microbiology, molecular biology, applied mathematics, and
physics, to (1) adapt new tools in genetic analysis and microscopy to
study microbial activity and gene exchange at a molecular level in
micro flow chambers, and (2) use mathematics to extrapolate the
findings to understand processes at higher scales in the subsurface.
By combining experiment with theory we may be able to determine the
major requirements for successful gene transfer. The broader impacts
of this project arise from the wide applicability of the results to
many areas including human health, disease propagation, medicine,
contaminant remediation, and evolutionary biology. All of these
phenomena involve the processes studied here, many in porous media
(subsurface or biotic). Educationally the project provides the venue
by which results from the collaborative study can be incorporated
into the PI's undergraduate and graduate courses in microbiology,
engineering, and mathematics. The PI's also have a solid record in
involving minorities and women in research, via the MARC/AIM program
at Purdue, and the Women In Engineering (nee' Women Engineering Link)
program at UC Davis, and this habit will be continued in this project.
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