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Now showing 1 - 10 of 15
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Finding Evidence of a Cancer Suppressing Mutation, rs 3814113

2011-05-09 , Small, James

For the past twenty years ovarian cancers has been one of the most well studied cancers. While many aspects of ovarian cancer are understood, scientists do not know what mutations cause tumor genesis. In recent years scientists have turned to genome wide association studies(GWAS) to determine what mutations are correlated to the disease, but these studies have not provided sufficient evidence to produce establish a causal link between a mutation and the disease. Instead of trying to create larger studies, scientists need to perform more focused smaller studies such as this one. This study will be investigating the findings of a recent GWAS performed by Dr. Song and his associates. However, instead of investigating the genetic information of thousands of individuals this study will focus on the complete profile of a twenty patients. This study will differ by including factors such as the patient and familial history of each of the cancer cases. By investigating this additional information this study will either prove or disprove the correlation between the SNP rs3814113 and ovarian cancer. after investigating genotypic ratios, onset of the disease, and risk ratios among pathological and genotypic groups this study found no evidence to support rs 3814113 as a cancer suppressing mutation.

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The Effect of Retrocues on CDA and Visual Working Memory Capacity in Young Adults

2011-05-09 , Delvin, Mary Courtney

Visual working memory is a system through which we retain information about objects in our visual environment. Through this system, information is stored so that it can be recalled or manipulated within the first few seconds of perception. Individual working memory capacity underlies numerous aspects of cognition including visual search, attentional processes, and concentration, and can predict performance on cognitive measures. Working memory is used in many everyday tasks and has implications in aging and the pathology of diseases. Contralateral Delay Activity (CDA) is a form of event-related potential measured with electroencephalography (EEG) that is thought to be modulated by the number of items held in working memory. In a related area of study, retrocues are attentional tools that are used to help individuals recall information from working memory. Retrocues are thought to improve visual working memory capacity by enhancing the active maintenance of relevant information held in working memory. This study attempts to show a relationship between retrocue usage and the CDA. We predict that retrocue trials will improve young adults’ performance on a working memory task and will enhance the CDA, showing that retrocues are an effective modulator of the CDA.

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Investigating the Effects of Disease on Predator-prey Dynamics in a Protozoan/Bacterial Model System

2011-05-09 , Stallings, Carrie

The relatively new field of eco-epidemiology investigates how diseases spread in relation to fundamental ecological topics. Knowing how diseases affect predator-prey dynamics, an important topic in ecology, may have beneficial applications in both conservation biology and biocontrol. However, most work in this field up to the current date has been purely theoretical (especially involving mathematical modeling). Experimental and observational evidence may or may not actually support mathematical models in the real world. In this experiment, we created microcosm communities with the ciliated protist species Tetrahymena pyriformis (predator), the bacterial species E. coli (prey), and bacteriophage T4 (pathogen) in order to determine how a pathogen affects predator-prey dynamics at the community level in a laboratory setting. The results indicate that T4 populations are benefited by the presence of the predator Tetrahymena, which may be due to the emergence of E. coli strains resistant to T4. If this is the case, Tetrahymena could be both hurting T4 on an ecological scale while helping T4 on an evolutionary scale.

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The effect of a pathogen on the population dynamics and reproductive method of Asplanchna girodi

2010-12-20 , Reynolds, Abigial Nicole

Studies show that the abundance of Asplanchna girodi can be affected by many factors including food density, temperature and pH. One such aspect not yet explored is the effect that parasitism has on Asplanchna girodi populations. During weekly samplings of a local lake, a parasitic oomycete was discovered to frequently infect the Asplanchna girodi population. Based on multi-year sampling data, this study supports recent work showing that parasitism of a zooplankton has the potential to have reproductive and evolutionary consequences. I show that epidemics of this parasite, Pythium, occur frequently and that an increased number of males in the population can be correlated to the presence of the parasite. Sexual reproduction involving males provides for Asplanchna girodi's only means of genetic recombination and production of diapausing eggs that overwinter. This study shows that there is a correlation between the rate of infection by Pythium and the density of males in the Asplanchna girodi population. By increasing the number of males in a population, the rate of diapause egg production is also increased. Infection by this parasite could therefore be associated with increased sexual reproduction and genetic recombination of A. girodi populations.

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RNA-mediated double-stranded break repair in mammalian cells

2011-05-09 , Taylor, Matthew

This study seeks to examine the capability of RNA to introduce mutations into genomic DNA, and to provide insight into the enzyme(s) responsible for this phenomenon. To do this, a double-stranded break is induced in HEK 658D cells, and oligonucleotides containing RNA tracts with homology to the area around the break are introduced to examine if they can mediate repair of this area. In the first part of the study, oligonucleotides are introduced that contain a single-nucleotide substitution at the site of the break, and if the RNA is used as a template for repair, then this nucleotide should be incorporated into the genome of the cell. Oligonucleotides are introduced that contain either all-DNA, or DNA with a 6-nucleotide RNA tract at the break. These two classes of oligonucleotides are homologous to either the forward or reverse strands of the area around the break. This allows us to examine if there is a strand bias for repair, and if that bias is the same for DNA- and RNA-mediated repair, which will provide clues into the enzyme involved in repair.

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Novel expression sites and genetic diversity of FoxP2 in Lake Malawi cichlids

2011-05-09 , Norsworthy, Michael

FoxP2 is a forkhead box-family transcription factor intricately linked to the development of learned motor skills, especially language in humans or vocalizations in other animals. It plays a prominent role in development and continues to be expressed in the adult. The gene has been thoroughly described in the brain, but transcripts have also been documented in areas such as in the lungs of mice (Shu et al, 2007). Mutations or deletions of FoxP2 cause widespread defects in brain morphology, vocalization ability, balance and coordination, and even lung development. Broad conservation of FoxP2‟s role in motor control and vocalization suggests the gene may play a similar role in vocally diverse Lake Malawi cichlids. Here, we probe cichlid FoxP2 expression using in-situ hybridization throughout development, sequence and annotate the FoxP2 gene across seven representative cichlid species, and search for polymorphisms. Expression in the brain, swimbladder, pharyngeal arches, and fins suggest FoxP2 plays a role not only in sensory development and fine motor control, but also in the development of non-neural sound-producing structures as well as the development or innervation of skeletal muscle. Genetic analysis of FoxP2 reveals polymorphisms which may be a source of species diversity in the development of any of the above functions, including vocalization. Two polymorphisms of note result in two amino acid changes near the DNA-binding domain of FoxP2. The natural phenotypic diversity of cichlid fishes makes them excellent candidates for further studies of the function and evolution of FoxP2.

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Characterization of the chemical defenses of Sagittaria graminea, a freshwater plant, against crayfish herbivory

2011-05-09 , Kendig, Amy

Herbivores powerfully impact community structure by altering biomass, species richness, and succession, which cause many plants to evolve chemical defenses against them. Chemical defenses have been well studied in marine and terrestrial systems, but studies focusing on freshwater chemical ecology have only recently begun to increase in number. The freshwater macrophyte Sagittaria graminea is relatively nutritious and found in many of the same habitat types as crayfish, which can consume large amounts of biomass. We looked to chemical defenses to explain how S. graminea can maintain its populations despite the presence of crayfish. In this study, we aimed to characterize the deterrent secondary metabolite(s) found in S. graminea through bioassay-guided fractionation. Additionally, we compared deterrence of stem and leaf regions to test for differential allocation of resources within individuals. Significant deterrence by several distinct fractions of S. graminea extracts indicates that more than one chemical is contributing to S. graminea’s defenses. Additionally, one of these fractions contains chemical characteristics similar to other identified freshwater plant defensive chemicals. We determined that the deterrent chemicals have relatively low polarity. However, the lack of significant differences between consumption of the stem and leaf region of S. graminea indicates that defenses are equally allocated throughout the individuals, despite the easier accessibility of the stem to crayfish in the wild. Characterization of the deterrent chemical(s) and investigation of differential resource allocation contribute to a relatively unexplored area of chemical ecology by providing insight into the structure and regulation of a widely distributed macrophyte’s defense.

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RNA-mediated double-stranded break repair in mammalian cells

2011-05-09 , Taylor, Matthew Bryce

This study seeks to examine the capability of RNA to introduce mutations into genomic DNA, and to provide insight into the enzyme(s) responsible for this phenomenon. To do this, a double-stranded break is induced in HEK 658D cells, and oligonucleotides containing RNA tracts with homology to the area around the break are introduced to examine if they can mediate repair of this area. In the first part of the study, oligonucleotides are introduced that contain a single-nucleotide substitution at the site of the break, and if the RNA is used as a template for repair, then this nucleotide should be incorporated into the genome of the cell. Oligonucleotides are introduced that contain either all-DNA, or DNA with a 6-nucleotide RNA tract at the break. These two classes of oligonucleotides are homologous to either the forward or reverse strands of the area around the break. This allows us to examine if there is a strand bias for repair, and if that bias is the same for DNA- and RNA-mediated repair, which will provide clues into the enzyme involved in repair.

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Escape Behavior in Temora longicornis when exposed to Karenia brevis and Alexandrium fundyense

2011-05-09 , Angra, Aakanksha

Recent studies have shown that copepods exhibit complex behaviors. Copepods are ocean-dwelling crustaceans that form the base of the marine food web. With the increase in global temperatures, there has been an increase in naturally occurring harmful algal blooms. The purpose of this project was to determine the effects of harmful algal blooms such as Karenia brevis and Alexandrium fundyense on the escape behaviors of the small North Atlantic copepod, Temora longicornis. The experiments were performed in the schlieren optics system tank. A siphon was used to mimic the fish’s mouth. Data were collected via a high speed camera. Detection distance, escape distance, and escape speed were analyzed. Temora longicornis escape ability was not affected in terms of escape speed and escape distance after feeding on A fundyense. Copepods exposed to K.brevis, however, exhibited the furthest escape distance, largest average escape speed, and highest maximum speed of all other treatments. This conspicuous escape behavior increases the probability that they will fall prey to visual predators. Increased predation rates on HAB-affected copepods may facilitate the bioaccumulation of brevetoxins up the marine food chain with possible deleterious effects on humans consuming these fish.

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Native parasite combating an invasive species: an oomycete vs. Echinogammarus ischnus

2010-12-20 , van Rensburg, Karla

In the context of invasions in ecology, parasites can play an important role in mediating the outcomes of competition between the native and invasive species. For example, a native parasite in the upper St. Lawrence River area has been found infecting both native and non-native gammarid amphipods, Gammarus fasciatus and Echinogammarus ischnus, respectively. Usually when the non-native species invades an area, the native amphipod is rapidly replaced by the non-native species. However, in this specific region the native amphipod was not replaced by the non-native species, and the non-native species was observed to be infected by a parasite. To determine infection rates in the native and non-native hosts, DNA was extracted from both species of amphipods and specific primers for the 18S rRNA gene were created to generate quantitative analysis of the incidence of the parasite in the amphipods. These data indicate that the effect of the parasite on the native and non-native amphipods could be the mechanism preventing the dominance of the non-native species in this specific area for the past ten years, since the parasite was found to infect the non-native amphipod more frequently and at a higher level than the native amphipod.

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