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Title: Thermal Resistance of Listeria Monocytogenes At Low Water Activity: Effect of Humectants
Creator: Wang, Peng
Date: 2012-04-25, 2012-05
Description: The thermal resistance of L. monocytogenes Scott A was examined in glycerol solutions, sucrose solutions, and peanut butters at different...
Show moreThe thermal resistance of L. monocytogenes Scott A was examined in glycerol solutions, sucrose solutions, and peanut butters at different water activities (aw) from 0.27-0.99. The analysis of D-values in glycerol and sucrose solutions shown L. monocytogenes has greater thermal resistance in sucrose solutions at each same water activity level (0.85 and 0.80). The calculated D-values were 13.80 ± 0.31, 6.38 ± 0.73, 3.02 ± 0.10 min in sucrose solution (aw = 0.80), and 9.39 ± 0.22, 4.86 ± 0.29, 2.40 ± 0.19 min in sucrose solution (aw = 0.85), compared to D-values of 1.20 ± 0.04, 0.36 ± 0.03, 0.12 ± 0.01 sec in glycerol solution (aw = 0.80), and 9.60 ± 0.20, 4.20 ± 0.26, 1.80 ± 0.10 sec in glycerol solution (aw = 0.85) at 72, 75 and 78◦C. In each menstrum the thermal resistance of Listeria increased significantly as compared to phosphate buffer. However, the comparison of D-values in glycerol and sucrose solutions failed to reflect a linear relationship between water activities and thermal resistance of L. monocytogenes. In peanut butter samples, the D-values were 16.53 ± 0.31, 9.06 ± 0.75, 7.13 ± 0.27 min and 35.36 ± 2.14, 23.10 ± 1.31, 17.73 ± 1.96 min for 3.13% and 9.38% sugar concentration respectively at temperatures of 80, 90, 100◦C. The Z-values were 56.08 ± 4.87◦C and 67.18 ± 8.44◦C in peanut butter with 9.38% and 3.13% sugar concentration. These results indicate increases of thermal resistance of Listeria with increased sugar concentration in a pure solution. The same protection effect of sugar did not appear to play a role in much increased thermal resistance of Listeria in peanut butter.
M.S. in Food Safety and Technology
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Title: A PRELIMINARY STUDY OF THE ODORANTS RECOGNITION BY AN OLFACTORY RECEPTOR DR30R2.1
Creator: Xiong, Rui
Date: 2013, 2013-12
Description: Dr3OR2.1 olfactory receptor is located in the zebrafish chromosome 2. It is initially reported as the only member presented in zebrafish...
Show moreDr3OR2.1 olfactory receptor is located in the zebrafish chromosome 2. It is initially reported as the only member presented in zebrafish olfactory receptor genes θ group. The functional study of Dr3OR2.1 is lacking. In order to find out the ligands that might activate Dr3OR2.1, a preliminary chemical screening was conducted in this study. Dr3OR2.1 was cloned from zebrafish cDNA library and inserted into pCI mammalian expression vectors with Rho-tag and without tag. The Dr3OR2.1 was transfected into Hana3A cells and tested for its cell-surface expression by immunocytochemistry. Ten amino acids and four bile acids were tested on Rho tagged and no tag Dr3OR2.1 transfected Hana3A cells. The result indicated that the presence of N terminal Rho-tag may cause the differences between the odorant response profile of these two Dr3OR2.1 constructs. In addition, Dr3OR2.1 is probably an amino acid olfactory receptor rather than a bile acid olfactory receptor.
M.S. in Biology, December 2013
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Title: PHYSIOLOGICAL AND BEHAVIORAL EVIDENCE THAT CHEMICALS IN THE ENVIRONMENT INFLUENCE DEVELOPMENT OF THE ZEBRAFISH OLFACTORY SYSTEM
Creator: Valesio, Eric
Date: 2013, 2013-12
Description: Olfactory imprinting is the process of producing life-long changes through neural modification that is independent of associative learning....
Show moreOlfactory imprinting is the process of producing life-long changes through neural modification that is independent of associative learning. Here, I provide data to demonstrate that olfactory imprinting in zebrafish leads to neurobiological and behavioral changes. I treated zebrafish with an amino acid (AA) or a bile acid (BA) mixture from 4 days post-fertilization (dpf) to 40 dpf. Behavior studies showed that fish treated with odorants for 40 days exhibited preferential responses to treated odorants, which was different from the controls. These behavioral changes were retained 3 months after the odor treatment was ceased. Whole-mount immunohistochemistry was conducted using antibodies for parvalbumin (PV) and OTX. We discovered that treated fish had increased PV and OTX expression in the olfactory epithelium (OE) at 7 dpf and increased PV expression in the olfactory bulb (OB) at 12 dpf. Detailed analysis indicated that increased PV expression was observed in the OE apical region of treated groups while OTX was increased in both the apical and basal regions of the OE. In three regions of the OB analyzed, BA treated fish showed a doubling in PV expression in all regions while doubling was in two regions in AA treated fish. Increased OTX expression was in the three regions of AA treated fish but not in BA treated fish. These data demonstrate that exposure to AA or BA during zebrafish development leads to long-lasting physiological and behavioral changes. The report also includes a study of embryonic zebrafish treated with SP600125 (anthrapyrazolone), an inhibitor of the c-Jun N-terminal kinase (JNK) signaling pathway. Zebrafish embryos were treated with 1.25 μM, 5 μM, or 12.5 μM of SP600125 from 18 to 48 hours post-fertilization (hpf) followed by evaluation at 120 hpf. Zebrafish treated at 1.25 μM were not affected developmentally while embryos treated at xv 5 μM and higher displayed numerous morphological defects including edemas, eye malformations and reduction in olfactory organ size. Overall, it was observed that treatment at 5 μM, SP600125 caused severe developmental defects and that these defects worsened with increasing concentrations. Taken together, these data indicate that the environment has a profound influence on zebrafish development.
PH.D in Biology, December 2013
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Title: INVESTIGATING DIRECTED EVOLUTION AND GENETIC ENGINEERING WITH VITREOSCILLA HEMOGLOBIN TO PRODUCE CULTURES FOR LOW AERATION BIOLOGICAL WASTEWATER TREATMENT
Creator: Kunkel, Stephanie
Date: 2014, 2014-07
Description: The dominance of hemoglobin (Hb)-expressing bacteria in biological wastewater treatment systems could improve oxygen utilization under low...
Show moreThe dominance of hemoglobin (Hb)-expressing bacteria in biological wastewater treatment systems could improve oxygen utilization under low dissolved oxygen (DO) conditions. Hb-proteins are versatile molecules that have several biological functions. Here, Nitrosomonas europaea has been transformed with various plasmids; of particular interest is a recombinant plasmid bearing the constitutive Amo1 promoter and the gene (vgb) encoding the hemoglobin from the bacterium Vitreoscilla. Expression of VHb was assayed using various visible spectral methods, and VHb production seen in this recombinant strain. There were several positive effects on N. europaea metabolism related to VHb expression that were seen, specifically the ability of cultures to convert ammonia to nitrite at a slightly higher rate as well as higher specific oxygen uptake rates (SOUR) at both high (near saturation, 7 mg O2/ L) and low (< 2 mg O2/L) dissolved oxygen (DO) conditions. In parallel to this, two activated sludge cultures from the same source were cultivated using synthetic wastewater seeded with activated sludge from the same source and were operated at high DO (near saturation) and low DO (0.25 mg O2/L) concentrations for 370 days. There were significant changes in the bacterial species and phyla present in each of the cultures at various time points during the 370 day operational period. In the low DO culture, over time, there was a much greater expression of single domain and truncated Hbs which may enhance utilization and delivery of oxygen to various enzymes as well as to the respiratory chain. A larger increase in heme b was also observed which coincides with this observation. By the end of the acclimation period, the SOUR values were about 30% greater in the low DO culture compared to the high DO culture. This indicated the successful adaption of the low DO culture to respire more efficiently and eventually outperform the high DO culture.
Ph.D. in Biology, July 2014
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Title: EXPRESSION AND PURIFICATION OF RECOMBINANT ASXL2 PROTEINS
Creator: Gururaja, Avinash Nidhadala
Date: 2012-07-22, 2012-07
Description: Polycomb Group (PcG) and the Trithorax Group (TrxG) proteins are two highly conserved proteins families which regulate transcription by...
Show morePolycomb Group (PcG) and the Trithorax Group (TrxG) proteins are two highly conserved proteins families which regulate transcription by modifying chromatin structure. The activity of these two groups of proteins is regulated by a special group of proteins known as Enhancers of Trithorax and Polycomb (ETP). Recently our lab has generated a mutant mouse model for an ETP Group gene, Additional sex combs-like 2 (Asxl2) (Baskind 2009). Asxl2 is highly expressed in heart during development and in adult life. Depending on the genetic background Asxl2 -/- mice either die as neonates with congenital heart conditions or live to adulthood but develop heart dysfunction. In order to understand the structural basis of Asxl2’s function we propose to express and purify various truncations/deletions of Asxl2 that are important for its function. We expressed four different truncations and one deletion of Asxl2 in E.coli as GST fusion proteins. GST-Asxl2 fusions were purified using glutathione beads. This completes an important milestone in our structural study. In the future the purified recombinant proteins will be used for protein pull down assays and biophysical assays aimed at understanding the structure of Asxl2, which will improve knowledge of chromatin-based transcriptional regulation in the heart and will facilitate the detection, prevention and treatment of heart diseases.
M.S. in Biology, July 2012
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Title: THE LENGTH-TENSION CURVE OF FLIGHT MUSCLE IN MANDUCA SEXTA
Creator: Wang, Geng
Date: 2015, 2015-05
Description: The synchronous indirect flight muscle (DLM1) is located in the thorax of the Hawk moth, Manduca sexta. It has the potential to be a model...
Show moreThe synchronous indirect flight muscle (DLM1) is located in the thorax of the Hawk moth, Manduca sexta. It has the potential to be a model system for cardiac muscle because both muscles have similar length-tension curves and they have similar passive properties (Tu & Daniel, 2004). An important and valuable property of the muscle is the temperature gradient between dorsal and ventral muscles which have a corresponding functional gradient between them. The functions of dorsal and ventral muscle appear to be regulated by the temperature gradient and changes in the phase of activation (N. T. George, Sponberg, & Daniel, 2012). Very little is known, however, about its other physiological properties. Here I measured the relation between tetanic tension and sarcomere length in chemical skinned dorsal and ventral muscle in order to further characterize the properties of the two muscle parts. Analysis of the results showed similarities and differences in the length of thick and thin filaments, maximum force, and rates of force generation between dorsal and ventral muscles. Maximal force was also plotted as a function of temperature in order to inquire into the physiological changes of muscle at various temperatures. The potential of DLM1 to be a model system for some aspects of cardiac muscle research was supported by the results of this study. The hypothesis that functions of dorsal and ventral muscle is regulated by the temperature gradient and changes in the phase of activation also was verified.
M.S. in Biology, May 2015
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Title: EFFECT OF CADMIUM CHLORIDE ON PROSTATE CANCER CELLS AGGRESSIVENESS
Creator: Gokuldass, Aishwarya
Date: 2013-04-30, 2013-05
Description: Cadmium is considered as one of the most toxic metals and is also classified as a carcinogen. It has similar properties to zinc, iron and...
Show moreCadmium is considered as one of the most toxic metals and is also classified as a carcinogen. It has similar properties to zinc, iron and copper, which allows it to cause changes in cellular functions. Metallothionein is a metal binding protein, which helps to reduce the toxicity of cadmium in biological systems. When there is excessive cadmium compared to available Metallothionein, unbound, labile cadmium induces indirectly oncogenicity and directly renal damage. The effect of micromolar and supra-micromolar concentrations of cadmium toxicity in causing cancer has been studied widely. Our hypothesis instead aims at the effects of submicromolar concentrations of cadmium chloride on aggressiveness of existing prostate cancer. Hence in this study prostate cancer cells such as PC-3 and LnCaP are exposed to various concentration of cadmium chloride. One of the characteristics of aggressive prostate cancers is Epithelial Mesenchymal Transition(EMT). Our results show that nanomolar concentrations of cadmium chloride induces EMT in PC-3 cells, but not in LNCaP cells.
M.S. in Biology, May 2013
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Title: DYSFUNCTION OF BONE-MARROW-DERIVED MACROPHAGES IN GDX KNOCKOUT MICE
Creator: Bonomo, Raiza Rafael
Date: 2016, 2016-05
Description: Macrophages are cells of the immune system responsible for clearing up the organism, removing damaged and dead cells, pathogens and other...
Show moreMacrophages are cells of the immune system responsible for clearing up the organism, removing damaged and dead cells, pathogens and other foreign substances. They remove and destroy these compounds by a process called phagocytosis, in which the macrophages recognize what is to be destroyed, engulf it and digest it in the lysosome. The phagocytosis mechanism requires special cytoskeleton configurations formed by actin branches that allow the engulfment of substances into the cells. The cytoskeleton structures formed by actin branching are also known to be necessary during the macrophage migration towards its target. Our group has shown that the small cytosolic GdX protein has an important role in the actin filament branching. Therefore, the aim of this study is to analyze the migration ability and the phagocytosis potential of wild-type (WT) and GdX knockout macrophages (KO). Bone marrow cells from mice were isolated and cultured in presence of Macrophage Colony-Stimulating Factor (MCSF) to induce cell differentiation into macrophages. The bone marrow derived macrophages were then subjected to phagocytosis and migration assays. The results from the phagocytosis assay indicated no significant difference in the percentage of cells capable of internalizing the beads or in the amount of engulfed beads between WT and KO macrophages. However, the results from the migration assay suggested a decrease in the migration ability in GdX KO cells when compared to WT macrophages. Therefore,our results imply that the lack of GdX may cause macrophage dysfunction.
M.S. in Cellular and Molecular Biology, May 2016
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Title: EFFECTS OF VORINOSTAT AND 17-AAG ON THE ANDROGEN RECEPTOR AND ANDROGEN-INDEPENDENT PROSTATE CANCER CELL SURVIVAL
Creator: He, Di
Date: 2012-10-10, 2012-12
Description: Prostate cancer is one of the leading causes of cancer-related deaths. The AR is known to play an important role in cell proliferation and...
Show moreProstate cancer is one of the leading causes of cancer-related deaths. The AR is known to play an important role in cell proliferation and cell survival during the development of prostate tumors. Chemical and physical removal of androgens is therefore commonly used to treat prostate cancer. AR regulatory drugs, such as Vorinostat and 17-AAG, are FDA-approved drugs designed to down-regulate AR expression and suppress tumor growth. However, the function of the AR in post-castration tumors is not clear. Recently, our laboratory and others have shown that the AR also has a pro-death function, especially in androgen-independent prostate cancer cells. To determine the function of Vorinostat and 17-AAG on AR expression levels and cell survival in androgen-independent prostate cancer cells, we treated 104-R1 cells, an androgen-independent prostate cancer cell sub-line, with either Vorinostat or 17-AAG. We found that both drugs down-regulated AR protein levels, although Vorinostat was more potent than 17-AAG. Neither drug independently caused significant cell death; however, at certain doses, both drugs induced cell morphological changes that correlated with AR expression levels. Interestingly, Vorinostat synergized with Adriamycin, a commonly used chemotherapeutic drug, to induce cell death, while 17-AAG suppressed Adriamycin-induced apoptosis in 104-R1 cells. These data suggest that the drugs that are effective for androgen-dependent prostate cancer might not be suitable for androgen-independent prostate cancer.
M.S. in Biology, December 2012
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Title: CLONING AND CHARACTERIZATION OF EXON EDITED HOTSPOT 1 ROD REGION DYSTROPHIN PROTEINS
Creator: Mahajan, Aayushi
Date: 2013, 2013-12
Description: Duchenne Muscular Dystrophy, DMD, one of the most common fatal genetic diseases, is caused by the absence of dystrophin protein. This protein...
Show moreDuchenne Muscular Dystrophy, DMD, one of the most common fatal genetic diseases, is caused by the absence of dystrophin protein. This protein is coded by the largest gene in the human genome, which has 79 exons and spans 2.4 Mbp. DMD affects 1 in 3600 boys and the average life expectancy of patients is 25 years. The most common type of defects leading to DMD are large exonic deletions that juxtapose remaining exons of incompatible phases, causing a frameshift. Inevitably this introduces a nonsense mutation (i.e. a stop codon) in the frame shifted exons and thus protein truncation. A related but milder condition called Becker’s Muscular Dystrophy, BMD, results when deletions are in-frame and so allow for the production of some, albeit modified, dystrophin protein. While there is no treatment available for DMD the recent clinical trials involving exon skipping suggest this will be highly promising treatment option. Exon skipping therapy is a strategy that uses anti-sense oligonucleotide analogs, AONs, to induce skipping of additional exons during mRNA maturation and thus restore the reading frame. This allows dystrophin translation to continue to its normal C-terminus, albeit with an internal deletion edit corresponding to both the original deletion, and newly skipped exon, which results in expression of protein thus converting the severe form of DMD to a milder form BMD. Frameshift causing deletions require exons that begin and end in different phases, and DMD deletions thus are clustered where such exons are located in, two so called ‘hotspots’ in the gene. The first of these occur in the region from exon 11-22 and is known as Hotspot 1. In many cases, DMD defects that are amenable to exon skip repair can be repaired in two or more alternative fashions by skipping of alternative exons. It is thought that the differences in severity of BMD, can range from being nearly as debilitating as DMD, to xi nearly benign, are at least in part related to the nature of the defect and its impact on the protein’s structure. Thus we are producing 5 different exon edited proteins from hotspot 1 rod region and assessing them for structure and stability as compared to unskipped fully functional dystrophin, to determine which edits hold the most promise of producing a well formed and stable edit.
M.S. in Biology, December 2013
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Title: SURVIVAL AND SANITIZER RESISTANCE OF SALMONELLA ENTERICA ENTERITIDIS ON SHELL EGGS
Creator: Vogan, Jill Ann
Date: 2011-05-01, 2011-05
Description: The Gram negative bacterium Salmonella sp. is the most common cause of gastroenteritis in the United States and abroad. Its life cycle...
Show moreThe Gram negative bacterium Salmonella sp. is the most common cause of gastroenteritis in the United States and abroad. Its life cycle persists when the bacteria is picked up from the environment and ingested by a host animal. The bacteria adhere to the host’s small intestine and penetrate into the sub-epithelial tissue where it causes diarrhea and vomiting. The bacteria redeposit into the environment via the aforementioned route; thus, repeating the cycle. Salmonella can infect a variety of hosts and different serotypes vary in severity. In addition to the disease causing infections of some host animals such as birds and reptiles provide a reservoir for Salmonella. Reservoir hosts can carry and transmit the bacterium without showing any signs or symptoms of infection. The avian host can pick up the bacteria, by ingestion of contaminated food and water, and deposit it onto the surface or inside the egg. Salmonellosis is then transmitted to human by consumption of contaminated eggs. Salmonella enterica serotype Enteritidis is the most common serotype associated with contaminated chicken eggs. Salmonella Enteritidis inoculated onto the surface of whole chicken eggs was able to survive for at least two hours post inoculation. The rate of cell death on the shell surface increased steadily for the first 40 minutes of drying and tapered through the two hour end point. The death rate increase may have correlated with drying time on the shell surface. Further, the bacteria were able to attach to the shell within 10 minutes of incubation. Morphological examination of cells surviving on egg shells showed collapsing of the surface when dried for 30 minutes. When allowed to dry on the egg shell surface for two hours, Salmonella was able to survive sanitization with either 200 ppm hypochlorite or quaternary ammonium based sanitizer. Interestingly, a more vigorous recovery method was required to remove bacterial cells surviving on the shell surface post sanitization indicating that the sanitizers caused increased attachment.
M.S. in Biology, May 2011
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Title: A SYSTEMS APPROACH TO MINIMIZE PESTICIDE HAZARDS ASSOCIATED WITH FRESH VEGETABLES
Creator: Kalle, Niranjan
Date: 2011-07-27, 2011-07
Description: Pesticides are used in agriculture for eradicating pests and to increase the yield and productivity crops. These pesticides show much effect...
Show morePesticides are used in agriculture for eradicating pests and to increase the yield and productivity crops. These pesticides show much effect on health of humans. There are different types of pesticides such as Insecticides, Herbicides, Fungicides and Pyrethroids. While there is a benefit for the use of pesticides, there can be a negative impact to human health. Exposure to these pesticides from ingestion or oral intake is the most common route of pesticide exposure. Removal of these pesticides from fruits and vegetables would lower the exposure and risk to human health from these pesticides. The objective of this research is to study the effectiveness of various washing methods for the reduction of pesticide residues from fresh fruits and vegetables. Samples of cherry tomatoes were treated with pesticide formulation of 120ppm which is prepared by mixing 6 pesticides (Bifenthrin, Chlorothalonil, Cyhalothrin, Cypermethrin, Malathion and Permethrin). Treated tomatoes were washed with solutions (water, Sodium hypochloride (80ppm), Peroxy acetic acid(80ppm), and Tween20(0.1%)). Ultrasonicator is used as a tool for washing along with the washing solvents. The % reduction of pesticides was determined by extracting the sample through QuECHERS (AOAC 2007.01) method and analyzed by using GC-MS and LC-MS/MS. The analysis of pesticide residues extracted from tomato samples by GC-MS and LC-MS/MS showed a significant reduction in pesticides when washed with peroxy acetic acid compared to sodium hypochlorite and Tween20. Washing with ultrasonicator in combination with washing solvents showed 10% more reduction than washing alone with solutions.
M.S. in Food Safety and Technology, July 2011
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Title: EVALUATION OF A NON-DESTRUCTIVE HIGH VOLTAGE TECHNIQUE FOR THE DETECTION OF PINHOLE LEAKS IN SEMI-RIGID PACKAGES FOR FOODS
Creator: Gera, Mohit
Date: 2012-04-23, 2012-05
Description: High-voltage leak detection (HVLD) is an emerging technology that has successfully been used to test the integrity of flexible food packages....
Show moreHigh-voltage leak detection (HVLD) is an emerging technology that has successfully been used to test the integrity of flexible food packages. It allows for nondestructive, fully automatic, and 100% on-line detection of pinholes as small as 10 μm in diameter. The applicability of this high-voltage technique to various semi-rigid packages, therefore, is of great interest to food industry. This research was conducted to evaluate and validate the effectiveness of the HVLD system and its processing variables on detection of pinhole leaks in semi-rigid packages through systematic factorial design and blind study experiments. The Student’s t-distribution and the corresponding P-value indicated that, among critical factors, package headspace had the greatest effect followed by dielectric constant, pinhole size, and food conductivity (p < 0.01). Strong interactions in between those variables were also observed (p < 0.05). In particular, two evident interactions between dielectric constant and food conductivity, and pinhole size and food conductivity contributed to the model at a significant level. Statistical Z-test analysis of results from blind studies (population size for each combination of package, food, and defect types = 90, defect rate = 0.05) showed that the HVLD technique is significantly effective in determining defective packages (p < 0.05). Results from worst case scenario study showed that there is no significant change in physical properties of plastic laminate lid films after inspection at highest voltage of 10kV. These results suggest that HVLD technique is a promising non-destructive method that can be safely applied to detect pinhole defects in a wide range of plastic based packages.
M.S. in Food Safety and Technology, May 2012
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Title: DETECTION AND ENUMERATION OF SALMONELLA SPP. AND E. COLI O157:H7 IN RAW SILO MILK INTENDED FOR PASTEURIZATION
Creator: Maddi, Neeraj Kumar Reddy
Date: 2011-05-02, 2011-05
Description: Knowledge on the initial bioburden (H0) in raw milk intended for pasteurization is a useful tool to enable risk assessments for both product...
Show moreKnowledge on the initial bioburden (H0) in raw milk intended for pasteurization is a useful tool to enable risk assessments for both product and process safety. In a nationwide survey, a total of 214 comingled raw milk samples were collected from unique silos in different regions of United States. The samples were analyzed for prevalence and levels of Salmonella spp. and Escherichia coli O157:H7 using the VIDAS® (bioMerièux) SLM and ECPT assays and cultural methods. Total Viable Count (TVC), Coliforms (CC), Enterobacteriaceae (EB), E. coli (EC) and Staphylococcus aureus (STA) counts in raw silo milk were analyzed using the TEMPO® Automated System (bioMerièux). Aerobic spore counts (ASC) in raw milk were analyzed by a modified Standard Method. Raw milk samples were directly streaked on to Methicillin-resistant Staphylococcus aureus (MRSA) agar. Forty seven out of 214 samples (21.96%) were positive for Salmonella spp. at an average level of 0.973 MPN/ml. Nineteen out of 214 samples (9.05%) were positive for E. coli O157:H7 at an average level of 0.069 MPN/ml. Presumptive MRSA was detected in 8 out of 206 (3.88%) raw milk samples; however biochemical analysis did not result in positive confirmation. The average counts for TVC, CC, EB, EC STA and ASC were found to be 4.62, 3.23, 3.56, 3.23, 2.36 and 1.42 log CFU/ml, respectively. There was no correlation observed between the quality indicating microorganisms (TVC, CC, EB, EC and ASC) and the presence of Salmonella spp. or E. coli O157:H7. Based on the literature studies, occurrences of these pathogens in raw milk were at low prevalence rates when the sampling was done at bulk milk tank levels. Higher volume samples taken from commingled silos resulted in higher prevalence rates of pathogens. The results obtained in this study can be used for establishment of Food Safety Objective (FSO) in raw milk intended for pasteurization.
M.S. in Food Safety and Technology, May 2011
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Title: Efficacy of Zapotin as a Therapeutic Drug Against Non Small Cell Lung Cancer
Creator: Mutreja, Karun
Date: 2011-04-18, 2011-05
Description: Lung cancer has been the leading cause of cancer related deaths around the world. The most common type of lung cancer, nearly 85% is Non Small...
Show moreLung cancer has been the leading cause of cancer related deaths around the world. The most common type of lung cancer, nearly 85% is Non Small Cell lung Cancer (NSCLC). This study provides an evidence of efficacy of Zapotin (5,6,2',6'-tetramethoxyflavone) against NSCLC cell line. Zapotin was found to be effective against A549 cells that express wild type p53. Since Zapotin increased the protein expression of p53 in A549 cells, its mode of action is expected through p53. Target proteins of p53, which are involved in the cell cycle arrest and apoptosis were found to be up regulated upon treatment of A549 cells with Zapotin. Effects of Zapotin were tested on the proteins involved in induction and stabilization of p53 viz. ATM, p300, Mdm2, Mdm4 and Snai1. A549 cells possess oncogeneic K-ras, which suppresses the p53 activity through a Snai1 mediated pathway of p53 degradation. Further translational inhibition studies provided an evidence of p53 stabilization rather than induction of p53 by Zapotin. Our results here indicate restoration of p53 function in NSCLC cells treated with Zapotin through the inactivation of Snai1 in K-Ras mutated cells with wild type p53.
M.S. in Biology, May 2011
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Title: Efficacy of Atorvastatin and Zoledronic Acid for PC3 and LNCAP Prostate Cancer Cell Proliferation
Creator: Yuan, Liang
Date: 2012-04-28, 2012-05
Description: Prostate cancer, ranking as the second most common cause of cancer-related mortality, afflicts more than 90% male populations older than 65...
Show moreProstate cancer, ranking as the second most common cause of cancer-related mortality, afflicts more than 90% male populations older than 65 worldwide. Conventional approach, androgen deprivation therapy, ever realized the shrinking of early-staged prostate tumors through depletion of androgens in body. However, people have gradually found that the regression is temporary, and subsequently the tumors recur and progress, which might be androgen independent. Once prostate cancer is progressed, current understanding seems to cope with prostate cancer is poorly understood. Atorvastatin (ATO) and zoledronic acid (ZOL) are both popular medications and work to control cholesterol level in blood and manage metastatic bone disease, respectively. Based on previous laboratory findings, we hypothesized that both of them might be able to play potential anti-cancer functions, and enhanced effects might be achieved by ATO+ZOL combination. Hence, we conducted experiments to characterize cellular response to ATO, ZOL, and ATO+ZOL in both AR-positive LNCaP and ARnegative PC3 prostate cancer cell lines. Besides, we studied potential mechanisms of actions of these two drugs. Our comprehensive characterization elucidates that ATO and ZOL are capable of imposing anti-cancer effects on both parental and all subclones of PC3 and LNCaP cells with different efficacies. Synergistic antiproliferative activities induced by ATO+ZOL were observed in both prostate cancer cell lines. We also found that ATO induced autophagy in PC3 cells, but not in LNCaP cells. ZOL did not induce autophagy in both cell lines. Moreover, ATO+ZOL treatment for 48h enhanced the induction of autophagic activity in comparison with ATO treated PC3 cells. Notably, preliminary pathway analysis based on microarray data demonstrates that in LNCaP cells, 7 KEGG pathways were affected by ATO whereas in PC3 cells ATO altered 47 KEGG pathways. These data suggested that ATO may be particularly active in AR- negative prostate cancer. These observations offer novel insights for understanding roles of ATO, ZOL and ATO+ZOL in LNCaP and PC3 cells. ATO and ATO+ZOL might provide benefits for prostate cancer patients and our results provide some evidences for further investigation of these two drugs for potential clinical application.
M.S. in Biology, May 2012
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Title: VITREOSCILLA HEMOGLOBIN AS A STRATEGY TO ENHANCE BIODESULFURIZATION IN RHODOCOCCUS IGTS8
Creator: Bai, Nan
Date: 2014, 2014-05
Description: The bacterium Rhodococcus sp. IGTS8 contains the dsz operon encoding enzymes for the 4S pathway, which enables it to use dibenzothiophene (DBT...
Show moreThe bacterium Rhodococcus sp. IGTS8 contains the dsz operon encoding enzymes for the 4S pathway, which enables it to use dibenzothiophene (DBT), an organic sulfur containing molecule found in petroleum, as the sole source of sulfur for its metabolism. The gene vgb from Vitreoscilla encoding hemoglobin (VHb) has been widely studied and is used for improving the usefulness of a large number of heterologous hosts, like prokaryotes, lower eukaryotes and even higher plants. We produced the engineered strain IGTS8[pRESX-vgb] in which vgb was introduced into Rhodococcus sp. IGTS8. We measured the growth and the ability of desulfurization of DBT for this transformed strain (compared to the untransformed host) under both high and low aeration conditions. From CO-difference spectra, we found that VHb was successfully expressed in this transformant and the expression level was similar to that in certain other heterologous hosts. The transformant had much greater growth than untransformed IGTS8, cultured under both high and low aeration in CDM with DBT as the only sulfur source (the transformed strain outgrew the untransformed strain by about 380 % under high aeration and 68 % under low aeration). Unfortunately, we found that the color of the product from reaction of the Gibbs reagent with the final metabolite of DBT produced by the transformant was not blue. This did not allow us to directly compare the desulfurization abilities of the transformant and the untransformed strain. We did another experiment to prove that IGTS8[pRESX-vgb] still used DBT as its sole source of sulfur by culturing this transformant in CDM without DBT. IGTS8[pRESX-vgb] cannot grow in CDM without DBT. One possible explanation for this result is that the final product of the 4S pathway in the transformant may be converted to a form other ix than 2-HBP. In any case, the much better growth of the transformant compared to that of the untransformed strain provides indirect evidence that VHb does enhance biodesulfurization.
M.S. in Biology, May 2014
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Title: THE STRUCTURAL BASIS OF MYOFILAMENT LENGTH DEPENDENT ACTIVATION
Creator: Hsu, Karen Hsiaoman
Date: 2014, 2014-12
Description: Titin-based passive tension is one of the mechanisms that modulate myofilament length dependent activation, the phenomenon that underlies the...
Show moreTitin-based passive tension is one of the mechanisms that modulate myofilament length dependent activation, the phenomenon that underlies the so-called Frank Starling Law of the Heart. The Greaser N2BA-G rat model, with a homozygous autosomal mutation in the titin gene, produce a longer isoform of titin that produce much less passive tension as well as a reduced degree of LDA. This provides a useful tool to test whether titin modulates sarcomere structure with changes in sarcomere length. Here we assessed sarcomere structure using small angle X-ray diffraction of intact, twitching papillary muscle in the diastolic phase of contraction at short and long sarcomere length. Comparison of our results from wild type and titin mutant rats indicated that the equatorial intensity ratio, I11/I10, decreases in both wild type and the titin mutant rats with increases in length indicating that the myosin heads are more associated with the thick filament backbone than the thin filament at long lengths. Analysis of the first myosin layer line shows that there is a radially inward movement of myosin heads in WT myocardium but not in the titin mutant when stretched. Difference electron density maps show the thick filament densities in wild type increases more than in titin mutant rats and that the densities of the thin filament are less in the titin mutant rats. Our data suggest, therefore, that increased calcium sensitivity at longer sarcomere length is not due to a radial extension of the myosin heads at long length. Rather, it is associated with transmission of titin-based passive tension from the thick filaments to the thin filament, resulting in increased ordering of the myofilaments at the hexagonal lattice positions requiring some sort of communicating structure, presumably crossbridges, between the thick and the thin filaments as part of the length transduction mechanism behind LDA. The X-ray diffraction studies showed that there are gross troponin structural cahnges when muscle is stretched indicating that troponin is an important regulator of LDA in the myofilaments. But the precise way in which troponin regulates muscle contraction is only partly understood. In the research reported here, we investigated the effects of cTnI phosphorylation of sites in human cardiac tissue using site-directed mutagenesis. Serine and threonine were replaced by aspartic acid (D) or glutamic acid (E) to mimic the phosphorylated state. Six recombinant human cardiac troponin complexes (hcTn), containing either hcTnI-WT, hcTnI-S5/6D, hcTnI-S23/24D, hcTnI-S42/44E, hcTnI-T143E and hcTnI-S150D were exchanged into skinned human cardiac fibers. Force and ATPase activity was measured as function of [Ca2+] at short and long sarcomere length (SL=2.0 and 2.3um). We found that LDA in the hcTnI-S150D substitution was attenuated, and was unchanged with the other sites. CD, as indexed by tension cost was decreased for hcTnI-S42/44E and hcTnI-S150D, and was unaffected for the other site substitutions. While some of these results were consistent with previous findings form rodent myocardium, others were not, suggesting that one should use caution in extrapolating from results in rodetn cardiac tissue to human cardiac tissue.
Ph.D. in Biological and Chemical Sciences, December 2014
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Title: Strategies for Improved Biodesulfurization in Genetically Engineered E.Coli Hosts
Creator: Ranganathan, Abhaya
Date: 2011-04-20, 2011-05
Description: Biodesulfurization has been an area of active research for the past few decades, in an effort to curb the amount of sulfur byproducts released...
Show moreBiodesulfurization has been an area of active research for the past few decades, in an effort to curb the amount of sulfur byproducts released into the environment. One key aspect of sulfur removal using biological techniques is the microbial conversion/utilization of dibenzothiopene (DBT), an ubiquitous component of organic sulfur compounds of crude oil. Three main enzymes are involved in 4S pathway of biodesulfurization; they are DszA, DszB, and DszC. DszD is a fourth enzyme that provides the necessary cofactors to Dsz A and DszC to complete their monooxygenase reactions in a number of bacteria with desulfurization capability, such as Rhodococcus erythropolis IGTS8. In this study, two ways to engineer bacteria, especially E. coli, for improved biodesulfurization of crude oil were investigated. The first was to express the dszD gene in E. coli in conjunction with the dszABC operon and study its effect on the growth pattern of the cells in minimal medium with DBT as the sole source of sulfur. The second approach was to clone the gene encoding sulpeptide S2, which is a sulfur-rich polypeptide, along with the desulfurization operon so that expression of sulpeptide would increase the demand for sulfur by the host cells. dszD and S2 were successfully cloned downstream of existing constructs of pGEM T-easy dszABC and pNW33N dszABCD and were expressed in E. coli strains BL21 and DH5α respectively. Growth experiments indicated marginal increase in the presence of dszABC compared to the unengineered strain and in the presence of dszD and S2; however, improved desulfurization activity was observed in the case of cells harboring dszD in addition to the dszABC operon.
M.S. in Biology, May 2011
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Title: MABC2 REGULATES CELLULAR AND MITOCHONDRIAL HEME CONTENT IN CARDIOMYOCYTES
Creator: Khechaduri, Arineh
Date: 2011-04-20, 2011-05
Description: mABC2 (ABCB10) protein is a mitochondrial inner-membrane ATP-binding cassette transporter. The structure of mABC2 is similar to that of ABCB8 ...
Show moremABC2 (ABCB10) protein is a mitochondrial inner-membrane ATP-binding cassette transporter. The structure of mABC2 is similar to that of ABCB8 (mABC1), which was shown to export iron from mitochondria into the cytoplasm. Based on the structural similarities we hypothesized that mABC2 is involved in export of heme from mitochondria into the cytoplasm for subsequent use in cytosolic enzymes. To study the role of mABC2 in cellular and mitochondrial iron homeostasis, we modulated the expression of the protein in neonatal rat cardiomyocytes (NRCM). We found that downregulation of mABC2 led to significant decrease in total cellular heme content. There was a trend toward increase in total cellular heme content with overexpression of mABC2, however the finding was not statistically significant (p=0.36). To measure mitochondrial heme content with mABC2 modulation we have successfully isolated mitochondria from NRCM. Overexpression of mABC2 significantly elevated mitochondrial heme content. It has been shown that mABC2 and mitoferrin-1 (Mfrn1) interact and form an oligomeric complex with ferrochelates to enhance mitochondrial iron importation for heme biosynthesis. Our findings are inconsistent with the proposed function of mABC2 in heme export out of the mitochondria, but support the hypothesis that mABC2 modulates heme synthesis via regulation of stability and activity of Mfrn1 and ferrochelatase in cardiomyocytes. This suggests that mABC2 may play a role in regulation of cellular iron homeostasis by regulating expression of cellular iron import and/or export.
M.S. in Biology, May 2011
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