Poster
Competition Winners / Abstracts - Natural Sciences 1
Natural Sciences 1 - 1st
Place
Structural Relationships Affect the Antioxidant and Neuroprotective
Efficacies of Ginkgolide Diterpenes and Other Constituents
From Ginkgo Biloba Leaf Extracts Against Induced Neurotoxicity
in Rat Hippocampal Explants in vitro
By Annalissa Vicencio, Manhattanville College
Certain bioantioxidants, such as Ginkgo biloba, may also
have neuroprotective properties, with clinical implications
for neurodegenerative diseases. The antioxidant efficacies
of the terpenoid and flavonoid fractions have previously been
studied on many cell lines, but structural mechanisms have
yet to be elucidated. Neuroprotective potency may be dependent
on hydroxyl reactivity. Previous studies in our lab have demonstrated
that Gin B attenuated verapamil-induced neuronal degeneration
in rat hippocampal explants and the flavonoid constituents
may play a neuroprotective role in maintaining calcium homeostasis.
In the present study, the neuroprotective efficacies of these
flavonoid and terpenoid constituents were explored through
individual pre-treatment exposures of hippocampal explants
followed by a neurotoxic insult by verapamil, a calcium channel
blocker, or sodium nitroprusside. Excised 1mm coronal brain
slices from 7-9 day old Sprague-Dawley rats were explanted
for 24 hours on Millicell inserts in 6-well plates and exposed
to either Gin A, B, C, or other bioantioxidants (20µg/ml)
for 24 hours and subsequently insulted with verapamil (5mM)
or SNP (100uM) for 24 hours. Morphometric data from cresyl
violet-stained frozen sections (Vibratome UltraPro 5000) were
analyzed with Motic Images Plus 2.0 software. Statistical
significance was determined using a one-way ANOVA and subsequent
post-hoc Tukey’s and Dunnett’s tests.
Natural Sciences 1 - 2nd Place
Probing the Stability of the Immunologically Active Truncated
Human Thioredoxin Via Electrostatics
By Janelle Tertullien, City College of New York (CUNY)
The structure of the inmunologically active truncated human
thioredoxin (Trx80) is unknown and high resolution structural
studies with standard techniques like Nuclear Magnetic Resonance
(NMR) Spectroscopy in solution are unsuitable due to the tendency
of Trx80 to aggregate at millimolar concentrations. For that
reason, we have chosen as one of many options to improve the
solubility of Trx80 via mutagenesis while maintaining its
biological activity. Through the use of bioinformatic tools
and based on the well-known structure of human thioredoxin,
we have evaluated parameters such as hydrophobicity/hydrophilicity,
the effect of removing its C-terminal on the stability of
the remaining structure, and selected the following mutants
of Trx80: Phe77Asp (F77D), Phe79Asp (F79D) and Phe41Arg (F41R)
for expression in an E.coli system. It was concluded from
our results from the ClusterW alignment that the mutagenesis
of the trx80 mutants was successful, and the results from
the protein electrophoresis(SDS-Page) showed that the amount
of mutant proteins that were expressed is suitable for further
studies.
Natural Sciences 1 - 3rd
Place
Glycine 3842 of the Mixed Lineage Leukemia Protein is Critical
for Proper Folding of the Catalytic SET Domain
By Benny Howard, Syracuse University
The Mixed Lineage Leukemia-1 (MLL) protein is a histone H3
lysine 4 methyltransferase that belongs to a class of proteins
that contain an evolutionarily conserved SET domain. MLL positively
regulates homeobox (Hox) genes, which are regulators of development
in multicellullar organisms. Mutagenesis experiments in the
Drosophila homolog of MLL, called Trithorax (trx), have identified
a point mutation in the SET domain that changes glycine 3601
to serine (called trxz11) and results in arrested homeotic
development and lethality. This glycine is highly conserved
across species among SET domain proteins, suggesting that
this amino acid plays an important role in the structure and/or
function of the SET domain enzymes. To test this hypothesis,
we introduced the equivalent mutation (G3842S) into the MLL
SET domain and compared the structural and functional properties
between the mutant and wild-type enzymes. Using enzyme activity
assays, we found that replacement of glycine 3842 with serine
abolishes enzymatic activity. Because it was noticed that
the G3842S enzyme precipitates more readily in solution, we
hypothesized that the loss of enzymatic activity when G3842
is replaced with serine is due to protein misfolding. This
was confirmed by light scattering and by analytical ultracentrifugation.
It was found that the mutant protein more readily forms high
molecular weight aggregates and is polydisperse. In addition,
velocity sedimentation studies reveal that the mutant protein
contains a larger frictional coefficient, consistent with
an altered conformation that experiences more viscous drag.
These data are consistent with a model in which a highly conserved
glycine is critical for the proper folding and activity of
SET domain lysine methyltransferases.
Natural Sciences 2 - 1st
Place
A Single Nucleotide Polymorphism in the Human OR3A1 Olfactory
Rreceptor Gene Discriminates Between an Intact and Pseudogene
Allele
By Lindita Ismaili, Kingsborough Community College
In mammals, initial detection
of chemical odorants occurs when an odorant interacts with
a specific olfactory receptor (OR) in the nasal cavity. Although
olfactory receptors are known to bind odorants, the specificity
of ligands has not been determined for most receptors. The
human olfactory receptors are encoded by 1000-1400 genes.
In mice, 20% of the OR genes are pseudogenes, but surprisingly,
over 60% of the human OR genes are pseudogenes or are segregating
between intact and pseudogene alleles. OR3A1 is a segregating
human OR gene with an intact allele frequency of 55% and a
pseudogene allele frequency of 45%. We have developed a PCR-based
assay that detects a single nucleotide polymorphism which
discriminates between the intact and pseudogene alleles of
the OR3A1 gene. We have used this assay to determine the genotype
of individuals and we plan to test these individuals for their
discrimination of different odorants. This information can
be used to correlate odorant discrimination with functionality
of the OR3A1 receptor and a similar assay could be used for
determination of ligand specificity of other olfactory receptors.
L. Ismaili is a student participant in the Collegiate Science
and Technology Program of the NY State Education Department,
grant number 0516051091.
Natural Sciences 2 - 2nd
Place
Elucidation of the Oxidative Stress Response in Drosophila
Melanogaster Adult Males
By Pedro Granados, LaGuardia Community College
Oxidative stress, which results from increased production
of free radicals and/or decreased levels of antioxidants,
has deleterious effects on male reproductive biology, and
can lead to infertility. Peroxiredoxin 3 (Prx3) is a mitochondrial
thioredoxin-dependent peroxidase that neutralizes excess peroxides;
Prx3 plays a cytoprotective role. We investigated whether
Prx3 plays a role in the oxidative stress response in male
flies. Adult transgenic male flies expressing ?-tubulin-GFP
were dry starved for 6 hours, and exposed to filter paper
soaked in 5% sucrose containing 0% (control), 0.3%, or 0.9%
hydrogen peroxide (H2O2). After 48h, total RNA was extracted
from whole flies and used for Reverse Transcriptase-Polymerase
Chain Reaction (RT-PCR) analyses. Prx3 mRNA levels increased
2-fold in males treated for 48h with 0.3% and 0.9% H2O2. We
next performed an initial screen to determine whether H2O2
treatment affects the testis. Phase-contrast and fluorescent
microscopy were performed on testicular squashes. H2O2 treatment
for 48h appears to adversely affect the cells at the apical
end of the fly testis, as indicated by decreased??-tubulin-GFP
signal in testicular squashes. In summary, 48h exposure to
0.3% and 0.9% H2O2 results in increased Prx3 mRNA levels in
males and decreased ?-tubulin-GFP in the apical cells of the
testis.
Natural Sciences 2 - 3rd
Place
Synthesis of Pyridinium and Imidazolium Ionic Liquids for
Toxicity Studies
By Xing Li, Queensborough Community College, CUNY
Ionic liquids (ILs) are salts with melting points below 100
°C. Attention has been drawn to the Ils lately because
of their relative non-volatility, non-flammability, wide liquid
range, and high conductivity. These properties make ILs good
candidates as potential green solvent alternatives to volatile
organic solvents. We have successfully prepared a series of
halide salts based on 1-methylimidazole and pyridine. 1-methylimidazole
and pyridine were reacted with alkyl halides of various chain
lengths to produce the corresponding quaternary ammonium halide
salts. The salts were converted to ionic liquids bearing the
phosphate and bis(trifluoromethylsulfonyl)imide anions. Degree
of color and reaction temperature was used to determine purity
level. The structures of the salts were confirmed using H-1
and C-13 Nuclear Magnetic Resonance spectroscopy (NMR). The
grades of purity were detected by using UV- Vis spectroscopy
and fluorescence. The liquids were screened for their toxicity
to a variety of microorganisms. Preliminary results indicate
that bacterial growth inhibition caused by ILs is dependent
on concentration, alkyl chain length and bacterial strain.
It was also observed that alkyl chain length affects mycelial
growth. This is part of a larger collaborative research project
where other similar series of ionic liquids will be prepared
and tested.
Natural Sciences 3 - 1st
Place
Interleukin-10 Inhibits Dendritic Cell (DC) Activity by Inducing
Apoptosis of Precursors Newly Committed to DC Growth
By Jean Bernard Lubin, SUNY Farmingdale
Dendritic cells are antigen presenting cells that regulate
adaptive (antigen-driven) immunity. Monocyte-macrophages,
while sharing functions with DCs, promote innate (nonspecific)
immunity. DCs and mono-macrophages share a common precursor.
Proteins known as cytokines regulate the growth of DCs from
these precursors. Interleukin-10 (IL-10) is a cytokine that
suppresses DC growth. However, molecular mechanisms underlying
this suppression remain poorly characterized. We hypothesized
that IL-10 inhibits DC activity by initiating an apoptotic
(programmed cell death) schedule at the onset of DC growth
from monocyte/DC precursors. To test our hypothesis, peripheral
blood precursors were cultured with cytokines sustaining DC
growth (GM-CSF/IL-4) in the absence/presence of IL-10. Temporal
analyses of Annexin V binding and cell morphology verified
that IL-10 induces apoptosis within 48 hrs. In order to identify
IL-10 targeted cells, we designed a flow cytometry-based strategy
allowing simultaneous evaluation of apoptosis and cell surface
phenotype (immunofluorescence analysis). Our results substantiate
that IL-10 mediates apoptosis of monocyte/DC precursors while
sparing monocyte-macrophage like cells. Surviving cells exhibited
exceptionally high phagocytic ability but lacked the capacity
to stimulate naïve T cells (a hallmark function of DCs).
Thus, IL-10 regulates DC activity by killing monocyte/DC precursors
upon commitment to DC growth while enhancing monocyte-macrophage
survival and innate immunity.
Natural Sciences 3 - 2nd
Place
The Role of Stat3 in Breast Tumorigenesis
By Jamie-Lee Foote, City College of New York
Signal transducer and activator of transcription 3 (Stat3)
is a transcription factor that is over-activated in approximately
50% of breast cancers. Studies suggest that primary breast
cancers with high levels of activated (phosphorylated) Stat3
respond poorly to chemotherapy. Studies also show that cancer-derived
cell lines that contain constitutively activated Stat3 undergo
growth arrest when the protein is abrogated. However, Stat3’s
definitive role in breast cancer tumorigenesis remains elusive.
Our aim is to determine whether expression of an activated
form of Stat3 (Stat3C) in the tissue of a breast tumor mouse
model can lead to enhance tumorigenesis in vivo under the
oncogenic background of polyoma virus middle T antigen (PyMT).
Our preliminary studies using tumors derived from MMTV driven
PyMT mouse lines indicate high levels of activated Stat3 in
tumors. Therefore, in order to achieve our goal, an inducible
system was created. MMTV-reverse tetracycline-dependent transactivator
rtTA (MTB) transgenic animals were crossed with a Tet-O-Stat3C
line resulting in doxycycline-inducible Stat3C expression.
Finally, to generate Stat3C/MTB/PyMT animals, MMTV-PyMT transgenic
mice were crossed with the MMTV-reverse/Tet-O-Stat3C double
transgenic mice. Tumorigenic analyses are performed at different
time points after doxycycline feeding. Techniques employed
for these analyses include western blot, RT-PCR and breast
tissue whole mounts.
Natural Sciences 3 - 3rd
Place
Is There a Cross Talk Between Toll/NF-?B & JAK/STAT Signaling
in Hematopoiesis?
By Jeffrey Uribe, City College of The City University of New
York
Drosophila is a model for studying hematopoiesis, regulated
by the Toll and JAK/STAT pathways. Loss-of-function mutations
in Ubc9, a negative regulator of the Toll pathway, result
in over-proliferation and differentiation of immune-active
blood cells and the formation of tumors. The same phenotype
occurs in larvae carrying gain-of-function mutations in the
fly Janus kinase gene, Hopscotch. The goal of my project is
to determine if constitutive blood cell differentiation observed
in Ubc9 mutants is mediated by the JAK/STAT pathway. We are
using a transgenic GFP reporter of STAT activity (10X STAT-GFP)
to examine which immune cells in Ubc9- are GFP positive. JAKgof
animals are used as a reference to study STAT activation.
Preliminary results show upregulation of JAK/STAT signaling
in specific cells within the anterior lobes of lymph glands
of both Ubc9 and JAKgof mutants relative to control animals,
although the expression pattern is different. Thus, STAT activity
is differentially activated in Toll and JAK/STAT pathway mutants.
We will now examine if increased 10X STAT-GFP expression in
Ubc9- background is dependent on JAK/STAT function. These
experiments will allow us to delineate the lymph gland cells
in which cross-talk is occurring and confirm that STAT pathway
is downstream of the Toll pathway.
Natural Sciences 4 - 1st
Place
Identification of Novel CTX-M Extended Spectrum Beta-Lactamases
in Escherichia coli Clinical Isolates
By Ronald L. McHenry, Jr., SUNY College at Old Westbury
This study aims to identify a class of clandestine beta-lactamases
in Escherichia coli which are phenotypically resistant to
ceftazidime, a third generation cephalosporin. Thirty-one
randomly selected single patient clinical specimens of Escherichia
coli isolated from sources that included urine, blood and
sputum were obtained from the Infectious Disease Research
Laboratory at New York Hospital Queens. Minimal inhibitory
concentration (MIC) experiments to determine the efficacy
of antibiotics were performed using E-test methodology. For
DNA preparation, isolates were grown using established protocols
that included cell lysis followed by ethanol precipitation.
Polymerase chain reactions (PCR) were done using primers specific
for two classes of beta-lactamases: CTX-M; Forward-(GCTTTATGCGCAGACGAGTG);
CTX-M: Reverse- (TGATTGGTGGTGCCGTAGTC) and KPC-2; Forward-(ATGTCACTGTATCGCCGTCT)
Reverse-(TTTTCAGAGCCTTACTGCCC). Amplified products were visualized
by agarose gel electrophoresis. PCR results of Escherichia
coli isolates indicated that 16/31 (52%) was positive using
KPC-2 primers and 14/31 were (48%) positive using CTX-M primers.
Eleven isolates contained both CTX-M and KPC-2 enzymes by
PCR. CTX-M beta-lactamases may not be detected in the clinical
microbiology laboratory because of their hydrolytic activity
towards specific third generation cephalosporins.
Supported by NIGMS-MARC GM08722
Natural Sciences 4 - 2nd
Place
Does High Sugar Intake Lead to Obesity?
By Emily Kyrillou, Barnard College
Over the last 30 years, the prevalence of obesity has increased
dramatically in the United States. Several investigators have
shown that the increased obesity incidence is associated with
increased consumption of sugar-sweetened beverages. I used
mice as a model system to determine whether increased intake
of sugar solutions necessarily leads to obesity. To this end,
I examined the effects of ad libitum access to sucrose (10%
and 34% solution) or fructose (10% and 34% solution) on adipogenesis
in four strains of mice (129P3, C57BL/6, FVBN and AKR). All
mice were given ad libitum access to chow diet and water during
the exposure period. I observed large strain differences in
(a) daily intake of the sugar solutions, and (b) weight gain
over the 40-day experiment. However, there was no clear relationship
between daily intake and weight gain across the strains. For
instance, the strain that consumed the most sugar solution
(FVB) failed to gain any weight, whereas the strain the consumed
the least sugar solution (AKR) gained the most weight. Such
results point to a complex relationship between sugar intake
and obesity.
Natural Sciences 4 - 3rd
Place – Tied
Prevalence of Enterotoxins (SEs) in Staphylococcus Aureus
(SA) Isolates From the Bronx, NY
By Natalie Robiou, Fordham University
The objective of our research was to determine the prevalence
of SEs in wound and blood SA isolates in 100 blood and 109
wound SA isolates that were sequentially collected from four
community hospitals in the Bronx. Comparable percentage of
MSSA and MRSA strains were found in wound and blood isolates.
Presence of 10 SEs (A-E, G, I, O, Q, TSST-1) was determined
by PCR. SE genes were frequently detected and only 14.4% of
SA isolates did not contain SE genes. The prevalence of individual
SE-genes was variable and as follows: SEI>SEG>SED>SEO>PVL>SEC>SEQ>SEB>TSST>SEA>SEE.
Combinations of SEs were common as phages, pathogenicity islands
and plasmids often encode for more than one SE. The egc cluster
(seg-sei-seo) was the most combination. Of note is that SE
genes were less common in SA strains that contained the Panton-Valentine
Leucocidin (PVL+) gene. The 38 SA PVL+ isolates were further
typed using RFLP. Nineteen of 23 MRSA were clone USA300, 2
USA400 and 2 other clones, while 9 different clones were identified
among the PVL+ MSSA isolates. In summary our data demonstrated
that SE genes are abundant in clinical SA isolates in the
Bronx. PVL + isolates are much more common in wound isolates
and carry less or no SE genes.
Natural Sciences 4 - 3rd
Place – Tied
Analysis of Lipids and Fatty Acids in NMU Rat Mammary Tumor
Cells After Treatment With Dietary Fatty Acids
By Aileen Fernandez, SUNY Purchase
Research has shown that cancer
cell proliferation increases with exposure to omega-6 fatty
acids, e.g., linoleic acid (LA), and decreases the exposure
to omega-3 fatty acids, e.g., docosahexaenoic acid (DHA).
In the present study, NMU cells were cultured with 10% serum,
or 1% serum in the presence or absence of DHA or LA for 3
days. Lipids were isolated and separated by thin layer chromatography
(TLC). Quantitation of the various lipids were done using
scanning densitometry. Fatty acids from the various lipid
fractions were examined using Gas-Liquid Chromotography/Mass
Spectrometry (GC/MS). Analysis of the lipid patterns revealed
that the dominant species were phospholipids and cholesterol.
Cholesterol esters were present in smaller amounts. Fatty
acid treatment of the cells resulted in no major changes in
the phospholipids and cholesterol esters. Differences were
observed in cholesterol levels with the various treatments.
For example, cholesterol levels were lower in LA and DHA treated
cells as opposed to cells treated with 1% and 10% serum. Phospholipids
found in cells after 3 days were phosphatidylserine (PS),
phosphatidylinositol (PI), and phosphatidylethanolamine (PE).
Phosphatidylcholine (PC) was present in smaller amounts. In
cells retreated with fatty acids before analysis, PC levels
rose, while levels of PS and PI dropped. Further analysis
using this model will help us to understand the role of exogenous
lipids in normal and cancer cell proliferation. Supported
in part by Grants: NIH 62012-05 and NSF Due 0524965.
Natural Sciences 5 - 1st
Place
Mus Musculus Atp8a1 and ATPase 1B and Plasma Membrane Phosphatidylserine
Translocation in Neuronal Cells
By Kelly Levano, College of Staten Island
Flippases, also known as aminophospholipid translocases (APLTs),
sequester phosphatidylserine (PS) to the inner leaflet of
the plasma membrane. Biochemical studies have shown that APLT
is an ATP-dependent, P-type Mg2+-ATPase activity. In our quest
to elucidate the protein or proteins responsible for the plasma
membrane APLT activity in neuronal cells, we have been studying
the roles of two P-type ATPases, Atp8a1 and ATPase IB, in
the translocation of the fluorescent PS analogue, NBD-PS.
Transient overexpression of Atp8a1 in the N18 neuroblastoma
cells causes a 2.5-fold increase in plasma membrane APLT activity,
but similar overexpression of ATPase 1B does not elicit an
increase in APLT activity. In our earlier studies, similar
high levels of overexpression of Atp8a1 in the hippocampal
neuron-derived HN2 cells yielded elevated, plasma membrane
APLT activity. However, relatively lower levels of stable
overexpression of Atp8a1 in the HN2 cells does not cause an
increase in the plasma membrane APLT activity but clearly
alters the time course NBD-PS translocation. PS internalization,
which is an important property of healthy cells, is lost in
apoptotic cells causing PS externalization and phagocyte recognition
of these cells by PS receptor-containing mast cells. Using
siRNA and antisense mediated suppression of both Atp8a1 and
ATPase 1B followed by rigorous kinetic analysis, we will test
the hypothesis that Atp8a1 and/or ATPase 1B contribute toward
or modify plasma membrane APLT activity in neuronal cells.
Supported by NIH CA77803-03; LS-AMP and MAGNET-AGEP.
Natural Sciences 5 - 2nd
Place
Depurination of RNA by Pokeweed Antiviral Protein (PAP): Fluorometric
Determination of released Adenine
By Ana Sanchez, John Jay College of Criminal Justice-CUNY
Ribosome inactivating proteins (RIPs) are naturally occurring
cytotoxic agents found in numerous plant, fungi, and bacterial
species. They have been recognized as important antiviral
agents. Pokeweed Antiviral Protein (PAP) is an RIP that inhibits
protein synthesis by depurination of the conserved sarcin/ricin
loop found on the large ribosomal Ribonucleic Acid (RNA).
Additionally, PAP has been found to bind and depurinate capped
mRNA. This project plans to measure the level of RNA depurination
by fluorometric assay of adenine released by PAP.
Ribosomal RNA (rRNA) will be incubated in a suitable temperature
and pH environment, having PAP present and absent. After incubation,
the RNA mixture is treated with cold ethanol, and the ethanol-soluble
fraction undergoes centrifugation. Free adenine present in
the recovered portion is treated and converted to its derivative
(ethenoadenine). Direct measurements of the derivative will
be performed by monitoring emission wavelength (400nm) using
an excitation wavelength of 280nm.
The amount of adenine released from rRNA will be determined
by the difference between fluorescence readings of PAP-treated
and non PAP-treated RNA. In addition, the amount of adenine
released will be quantitated by comparison with free adenine
controls.
Natural Sciences 5 - 3rd
Place
Chiral Recognition of a Fish Pheromone by CD-Sensitive Dimeric
Zinc Porphyrin Host
By Ekaterina Chadwick, John Jay College of Criminal Justice-CUNY
The following is the determination of the absolute configuration
of 17, 20 ??-dihydroxy-4-pregnen-3-one, a fish pheromone,
by use of the Zinc-porphyrin host-guest CD exciton chirality.
The protocol relies on a host-guest complexation mechanism:
the chiral substrate is derivatized to give a bifunctional
conjugate ("guest") that form a complex with a dimeric
zinc porphyrin host that acts as a "receptor". The
two porphyrins in the complex adopt a preferred helicity related
to the substrate’s absolute configuration. The absolute
configuration of the substrate is confirmed by molecular modeling
studies.
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