Stephen Curtis |
 | Research Advisor & Department
Alex Nikitin - Biomedical Sciences
Name of Project:
The Effects of p53 and Rb1 Inactivation on the Motility of Cells of the Soft Tissue Abstract:
The protein products of the p53 and Rb1 tumor suppressor genes are important players in the pathways of apoptosis induction and cell cycle regulation. Alterations in these genes, or their related pathways, have been found in over seventy percent of all human cancers. Soft tissue sarcomas rank among the top five most commonly occurring cancers in patients under the age of twenty, yet tumors of the soft tissue are very difficult to diagnose correctly and are some of the least well understood forms of cancer. Our lab has developed a model in which concurrent inactivation of p53 and Rb1 in cells of the soft tissue results in tumor formation in all trials, with malignant fibrous histiocytomas being the most frequent. This model utilizes the Cre-loxP system for conditional gene inactivation via subcutaneous injection of recombinant adenovirus that expresses Cre-recombinase in mice engineered with loxP sites flanking both the Rb1 and p53 genes. To better understand our model, possible variations in susceptibility to both adenovirus infection and Cre-mediated gene excision among cell types within the soft tissue, must be elucidated. Flow cytometry analysis and fluorescence activated cell sorting will be performed to identify any such differences and further analyze the potential basis of the disparity. This model will also be used to analyze the effects of Rb1 and p53 inactivation on cell motility. Cell motility is a major factor in malignant disease, as it is a necessary feature of invasive and metastatic cancers. Preliminary results obtained from primary cell cultures derived from these mice suggest that inactivation of Rb1 and p53 does in fact lead to increased cellular motility. The use of multiphoton imaging, through a collaborative effort with the applied physics department, enables us to study single cells in the subcutaneum of a living mouse, non-invasively. By fluorescently tagging cells in which Rb1 and p53 is inactivated, we will be able to directly visualize and track their motility. The cells will be challenged through the use of various chemoattractants and the rates of movement will be measured and compared to wild-type controls. Such a study surpasses the common cell culture assays for motility, bringing the analysis out of the Petri dish and into a much more natural environment: a living mouse.
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Susanna Curtis |
 | Research Advisor & Department
Irby Lovette - Ecology and Evolutionary Biology
Name of Project:
Genetic Variation and Plumage Ornamentation in the Eastern House Finch Abstract:
The house finch is a native western North American bird that underwent a population bottleneck during its introduction to the eastern United States in 1945. The eastern population is likely derived from only 24 individuals who survived that winter. Because of this population bottleneck, the current population of eastern house finches, which has now spread across all of the eastern US, is thought to be less genetically diverse than its western counterpart. Secondary sexual traits in males are often thought to indicate the health or relative fitness of an individual. Such traits are therefore often under selection by female choice. Female house finches (Carpodacus mexicanus) show a strong preference for bright red plumage ornamentation, which is shown to be derived from cartenoid pigments males sequester from the diet during molt. Males exhibit this bright red plumage in patches of varying size and brightness, the females showing preference for the birds with the largest and brightest patches. However, behavioral studies have shown duller males make a stronger investment in parental care then do the brighter males; this leads to the theory that brighter males must confer some other advantage to their young. There are multiple theories as to what genetic the brighter males confer to their young. I am testing one, which hypothesizes that brighter males are more genetically diverse and confer the advantage of heterozygosity. I am testing this theory with 30 captive male house finches whose color was measured with a spectrophotometer. I have extracted DNA from the blood of the males and am currently using PCR to genotype the males at ten microsatellite loci. I am measuring genetic diversity as the proportion of loci at which males are heterozygous. If genetic diversity is the advantage being conferred to the young by bright males then the brighter males should exhibit more heterozygosity, as should their offspring.
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Christopher Daeffler |
 | Research Advisor & Department
Jon Njardarson - Chemistry and Chemical Biology
Name of Project:
Ammonium Ylides: A Path to Amino Acid Abstract:
Ammonium ylide intermediates offer convenient, one-step syntheses for protected a-amino acids, such as leucine. The ylide is formed in the reaction between a tertiary amine and a carbene ester. Carbene generation is achieved through the catalytic decomposition of a diazo ester via rhodium and copper catalysts. The ammonium ylide can follow multiple reaction pathways, the [2,3] rearrangement being the one in which we are most interested. Our goal is to determine which catalysts favor the [2,3] rearrangement and which catalysts promote side reactions that do not involve an ammonium ylide. Side reactions include cyclopropanation and the Stevens rearrangement. Furthermore, we want to control stereoselectivity through either chiral catalysts or chiral reactants. Solvent, temperature and concentration also play a role, and will be investigated. As proof-of-concept examples, we would like to synthesize biological a-amino acids such as leucine and isoleucine.
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Juliane Deacutis |
 | Research Advisor & Department
Jeffrey Scott - Entomology
Name of Project:
Population Genetics and Evolution of Resistance to Spinosad in the House Fly, Musca domestica Abstract:
My proposed research project will be an extension of a study I completed last year, when I determined baseline responses of six different house fly strains to the novel insecticide, spinosad, and evaluated different bioassay methods. The strains were from hog, poultry, and dairy farms located in three states in the Eastern USA. I found a possible correlation between farm type and spinosad resistance, with poultry and hog farms having slightly greater resistance. I also found that topical application gave the steepest slope (dose-response line), which translates to the lowest margin of error; it was also the most time and cost efficient manner of application, and maintained the most similarities with actual field exposure. This summer spinosad will be released for use on poultry, dairy, and hog facilities. Collections from several facilities will be made, with some farms using the insecticide and others not. House flies will be collected before and after the season starts. I will conduct topical bioassays with spinosad on my six strains to determine whether the mortality to the insecticide changes over the spraying season, and save the survivors. This summer’s data will also be compared with last summer’s data. I will test approximately six-hundred animals for each strain. The survivors of the insecticide exposure will be saved for genotyping so that I can amplify a fragment of the gene responsible for resistance (MdnAchR7) by PCR. These fragments will be sequenced in order to determine if the individual has the resistance allele or not. I will then compile this data and create a comparison between before spraying season and after spraying season. I expect that before the season starts there will be a low frequency of the resistance allele, and after the season starts there will be a high frequency. Also, the farms that don’t spray spinosad are expected to have a consistently lower frequency of the allele than those farms that are spraying. One possible diverging project, which I may explore during the school year, is assessing the fitness costs for spinosad resistance, which could include impacts such as increased population, decreased ability to overwinter or decreased mate acceptance.
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Manisha Deb Roy |
| | Research Advisor & Department
Robert Gilmour - Biomedical Sciences
Name of Project:
Ventricular Fibrillation and Sudden Cardiac Death Abstract:
Ventricular fibrillation (VF) is one of the leading causes of death around the world. There are several hypothesis about the electrical signals in the heart that lead to fibrillation. One of them is the restitution hypothesis, which states that VF results if the slope of the restitution curve, that is the plot of Action potential duration versus diastolic interval, is greater than 1. Our project includes collecting data from purkinje fibers and ventricular muscle, excised from canine hearts. The fibers are stimulated using bipolar electrodes to model heart rhythms before, during and after VF and the resulting action potentials are recorded using micro-electrodes. The collected data is then analysed using a computer program that helps in constructing restitution curves. The analysis of the data is being used to construct useful models of the heart that will enable us to discover treatments to prevent VF.
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J. DeMeo |
 | Research Advisor & Department
Maureen Hanson - Moledular Biology and Genetics
Name of Project:
RNA Editing in Rice Chloroplasts Abstract:
RNA editing in chloroplasts is the post-transcriptional modification of the bases, usually involving a change from a cytidine to a uracil, which results in the encoding of a conserved amino acid sequence (Tsudnzuki et al., 2001). This is thought to occur to protect against mutations that could have lethal consequences for the cell (Peeters and Hanson, 2002) and has been shown to occur in all higher plants to some degree but has been most notably studied in maize and tobacco (Corneille et al., 2000). RNA editing also occurs in mammals, such as the well studied apoB protein, but occurs for protein diversification (Wedekind et al. 2003) rather than conservation of sequence. The aim of my project is to analyze the RNA editing that occurs in rice in order to be able to screen photosynthetic mutants for possible genes involved in the editing process. I will be using a specialized sequencing method called poison primer extension that allows me to quantify the ratio between edited and unedited transcripts. Rice is a much better candidate than maize or tobacco because its entire nuclear genome has been sequenced and known mutants are available in specific genes of interest. The information obtained from this project will increase our understanding of RNA editing and identify proteins involved that so far have been extremely enigmatic. Reference: (1) Corneille S, Lutz K, Maliga P (2000) Conservation of RNA editing between rice and maize plastids: are most editing events dispensible? Molecular Genome Genetics 264: 419-424. (2) Peeters NM, Hanson MR (2002) Transcipt Abundance Supercedes Editing Efficiency as a Factor in Developmental Variation of Chloroplasts Gene Expression. RNA 8: 497-511. (3) Tsudzuki T, Wakasugi T, Sugiura M (2001) Comparative Analysis of RNA Editing in Higher Plant Chloroplasts. Journal of Molecular Evolution 53: 327-332. (4) Wedekind JE, Dance GS, Sowden MP, Smith HC (2003) Messenger RNA editing in mammals: new members of the APOBEC family seeking roles in the family business. Trends Genet. 19: 206-217.
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Jill Demers |
 | Research Advisor & Department
Jeff Doyle - Plant Biology
Name of Project:
Phylogeny of Mitochondrial and Chloroplast Genes Abstract:
My research project will compare the phylogeny of mitochondrial and chloroplast genes in Glycine, a genus of plants that includes soybeans. Phylogenetics is the study of relationships among organisms. These relationships can be determined by comparing DNA sequences. Chloroplast genes are often used for studying plant phylogeny, as they show more variation among species than nuclear or mitochondrial genes. The purpose of my project is to study whether there are any differences in the phylogeny of chloroplast and mitochondrial genes in Glycine, which will show if using chloroplast genes alone gives an accurate phylogenetic tree. I will extract DNA from a number of plants in Glycine. Several mitochondrial and chloroplast genes will be amplified by PCR and then sequenced. I will then make two separate phylogenetic trees of mitochondria and chloroplasts. Differences between these trees could show differences in modes of inheritance of mitochondria and chloroplasts. This project will also give a more accurate description of the evolutionary relationships in Glycine.
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