2010 - Undergraduate Research, Scholarship and Creative Activity

Bacterial strain surface charge was only slightly
affected by ionic strength, and low pH
conditions. Results more importantly helped to
show that PLGA nanoparticle surface charge
could be modulated to mimic bacterial surface
charge to ultimately increase uptake by M-cells.
Studying the electrostatic properties of
nanoparticles can give a better understanding of
functionality of M-cells to ultimately aid in
designing efficient and effective mucosal
vaccine vehicles.
Fluctuation Induced Forces Between Foreign
Objects in a Biological Membrane
Nancy Bernal-Flores, Physics
Co-authors: Eugina Olivas, Chemistry/ Physics
Hector Garcia, Physics
Kriti Dube, Mathematics
Dong Gui, Physics
Hsiang Ku-Lin, Physics
Contributors: Umar Mohideen, Leonid Pryadko
Mentor: Roya Zandi
Department of Physics and Astronomy
The biological lipid bilayer membrane provides
the stage for vital surface cellular processes,
such as endocytosis and vesiculation. A number
of recent simulations indicate the presence of
attractive forces between inclusions embedded
in a lipid membrane. The focus of these
simulations has been on the forces associated
with the elastic energies; in particular, on the
forces mediated by the membrane curvature
(Benidict J. Reynwar et al, 2007). The goal of
our research is to show that the interaction
between membrane inclusions is a consequence
of the thermal fluctuations of the lipid
membrane. We examine the trajectories and
interaction of glass and polystyrene microspheres
over a free standing bilayer membrane
using fluorescence-interferometry methods.
These observations provide information for
analysis of relevant physical factors such as
membrane curvature, electrostatic and Casimir
forces, Brownian motion, and thermal lipid
bilayer perturbation interactions. Results suggest
that fluctuation induced forces may lead to a
microsphere bound-system formation and microsphere
aggregation. Future experiments are
under development to test interactions between
foreign objects such as viruses and various kinds
of proteins embedded in the surface of lipid
membranes.
The Evolutionary Breakdown of Symbiotic
Cooperation between strains of
Bradyrhizobium japonicum and their plant
hosts
Kameron Black, Neuroscience
Mentor: Joel Sachs
Department of Biology
Symbiotic relationships among plants and many
other living organisms serve as necessary roles
in human life. Many of them benefit us in
digesting foods and processing key nutrients,
while others aid in the success of major cash
crops. Yet a significant amount of these
beneficial ties have been found to transform into
uncooperative and even pathogenic bacterial
strains. These evolutionary transitions can have
devastating effects on symbiont-dependent
activities. Such affects can include harmful crop
yield reductions and emergent human
pathogenesis. The evolutionary origins and
genetic causes of these harmful transitions have
not yet been discovered and therefore my work
will involve investigating questions such as:
―With what frequency do these transitions occur
in nature?‖, ―Are there specific parts of the
bacterial ‗evolutionary tree‘ in which strains lose
their symbiotic ability?‖, and ―What conditions
allow for these transitions to occur?‖ The
methods for investigating these questions
involve attaining a sufficient model for the
observations. This has been found in the strain
Bradyrhizobium japonicum and its interaction
with a bean plant host, Lotus Strigosus. Upon
acquisition of a number of wild strains of the
bacteria, the genomes of the strains will be
sequenced through methods of archiving,
extraction and replication of the DNA. After the
data has been collected, analysis of the
information should correlate with certain
expected outcomes such as a degradation or loss
of the bacterial symbiosis loci. In addition, an in
vitro analysis of the bacterial response to living
conditions absent from a plant host will be
carried out. The targeted outcome of these tests
is to observe whether the bacterial symbiosis
Fourth Annual UCR Symposium for Undergraduate Research, Scholarship and Creative Activity
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