Journal of Biological Research, Vol. 6 (2005)
Effects of Carbohydrate, Lipid, and Protein Supplementation on Biofilm Formation and Antimicrobial Treatment of Common Bacterial Populations Causing Dental Caries. BRETT AMEDRO, Department of Biology, Hartwick College, Oneonta, NY 13820. Dental plaques, which are now recognized to be microbial biofilms, are a form of bacterial communities that adhere tightly to the surfaces of the teeth. The microbial compositions and sizes of oral biofilms contribute to the development of dental caries, which is tooth decay that causes periodontal diseases. The aim of this study was to test, in vitro, the effects of elevated carbohydrate, lipid, and protein concentrations on biofilm formation and susceptibility of these biofilms to anti-microbial treatment. Four common oral bacterial species, Streptococcus mutans, S. sanguis, Neisseria sicca and Lactobacillus casei, were grown together in wells of a slide chamber in media supplemented with water (control), sucrose (carbohydrate), extra virgin olive oil (lipid), or trypticase peptone (protein) and incubated for 48-hours at 37°C. Biofilms were then treated with 0.2% chlorhexidine, an anti-microbial agent, for 120 seconds. Biofilms were stained with LIVE/DEAD BacLight (Molecular Probes) fluorescent stain to acquire measures of total and dead cell material present. Data were analyzed using ANOVA with Tukey post-hoc tests. Supplementation with sucrose, oil, or trypticase peptone significantly decreased the amount of cells in the biofilms (p< 0.001) and the sizes of the supplemented biofilms were not significantly different from one another (p>0.05). Chlorhexidine treatment had no effect on the number of dead cells in any of the biofilms (p>0.05). These results suggest that nutrient supplementation could negatively affect biofilm formation overall, possibly due to inhibiting biofilm attachment. In addition, the results suggest that supplementation does not help or hinder susceptibility to antimicrobial treatment. Faculty supervisor: Dr. Mary Allen.
Childhood Obesity: Etiology, Outcomes, and Clinical Implications. ERIN BONJOUR, Department of Biology, Hartwick College, Oneonta, NY. Childhood obesity is a growing health epidemic worldwide and is associated with many health consequences and complications such as hyperlipidemia, glucose intolerance, non insulin dependent diabetes mellitus (NIDDM), and coronary heart disease. The etiology of childhood obesity is an essential factor for the establishment of effective clinical treatment guidelines for health promotion and disease prevention. Obesity in children is defined as excess of body fat greater than the 95th percentile for age and sex specific growth, which correlates with the adult morbidity and mortality cut off values (Power et al., 1997). A review of the literature demonstrated a multi-factorial relationship between genetic, prenatal environment, postnatal environment and parental influences relating to the etiology of the disease. Genetic factors influencing childhood obesity and overweight include Syndrome X (Stewart et al., 1995). The prenatal environment, related to maternal tobacco use and maternal malnutrition correlates with higher risk of obesity during childhood. Breastfeeding versus bottle-feeding reduces the risk of obesity through adolescence. Parental influence on childhood obesity relates to feeding style and physical activity. Three feeding styles have been identified—permissive, authoritarian, and authoritative, with only authoritative feeding reducing the risk for obesity during childhood (Birch & Davison, 2001; Fisher & Birch, 1999; Branen & Fletcher). The research suggests that children with more active parents are less likely to participate in sedentary activities than are children of sedentary parents (Hodges, 2003). Social and behavioral learning theories are discussed regarding effective clinical intervention. Future research regarding specific gene identification, maternal fetal risk factors, and cultural influences will increase the effectiveness of clinical interventions. Faculty supervisor: Dr. Allen Crooker
The Power of Subliminal Messaging. STEPHANIE BUTTACCIO, Department of Biology, Hartwick College, Oneonta, NY 13820. Cognitive and social psychologists are now learning that stimuli presented subliminally can have a considerable influence over a variety of cognitive processes, such as emotional responses. In addition, previous studies have shown that women are more emotionally expressive than men. It is unclear, however if women are more susceptible to the emotional modulation of behavior imposed by an affective stimulus presented subliminally (Pereira et al., 2004). In order to compare the influences of subliminal messaging on men and women this study consisted of two experiments. In the first experiment 20 volunteers were asked to rate a neutral picture, based on their first impression, on a scale of 1 to 7 (1 being unpleasant and 7 being pleasant). Before each picture a negative prime such as “bored,” or a positive prime such as “happy” was presented subliminally for 1 ms; 5 different positive and 5 different negative words were used. The results suggest that regardless of the subliminal prime, there was no significant difference (p>0.10) between male and female emotional response ratings. A second experiment was conducted with 8 volunteers and the same pictures used in the first experiment; however, in the second experiment only the two most influential primes, one positive (“enjoying”) and one negative (“torture”), were used. The results show that the most influential negative and positive subliminal primes had a significant effect (p<0.001) on the subject’s emotional response ratings. Results from experiment two demonstrate that there is a significant difference between the influential negative and positive subliminal primes. Faculty supervisor: Dr. Allen Crooker.
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Is Selective Predation by Fish a Cause of the Displacement of Native Crayfish by Orconectes rusticus? ERIN CARVIN, Department of Biology, Hartwick College, Oneonta, NY 13820. Orconectes rusticus, the rusty crayfish, is native to the Ohio River and its tributaries but has been recently expanding its range within North America, primarily because of introductions by anglers. O. rusticus is now found in several states, including the upper Susquehanna River region of New York State. The rusty crayfish is in the process of displacing previously existing crayfish species, such as Orconectes obscurus, in this river system. One hypothesis for why O. rusticus is able to displace native crayfish, developed from studies conducted in Wisconsin lakes, is that the native species are more susceptible to predators that the non-native rusty crayfish. I tested this hypothesis experimentally with species collected from the upper Susquehanna River basin. I compared the rates of predation by smallmouth bass (Micropterus dolomieu), a local crayfish predator, on equal numbers of similar sized O. rusticus and O. obscurus in large pools and analyzed the results of a previous similar experiment using another native species, O. propinquus. In both experiments, predation on O. rusticus was significantly lower than on the native species. Thus, local native crayfish species are more susceptible to predation by smallmouth bass than non-native O. rusticus, supporting the hypothesis that differential predation by fish contribute to the rusty crayfish’s success as an invader. Faculty supervisor: Dr. Mark L. Kuhlmann.
The Analysis of Cell Lineage and Cell Differentiation Using Microinjected Fluorescent Markers. MARK D. CHRISTOPHER, Hartwick College, Oneonta, NY. The purpose of this study is to formulate a working plan for microinjecting early stage embryos with a cell marker. This will sanction further studies of cell fate commitment and lineage restrictions to be performed. Fluorescein isothiocyanate dextran was injected into Rana pipiens embryos in the early blastula stage. The embryos were then stored at 16°C for two weeks until they reached the tadpole stage. The tadpoles were then fixed in formalin and sectioned using histology. The sections were observed under UV light to detect fluorescence. The injected embryos fluoresced very brightly, though the marker did not remain localized in groups of cells and instead diffused throughout the tadpole. A few brightly fluorescent cells were detected. These were scattered, possibly indicating intermingling of cell lineages. By perfecting this technique, future Hartwick students will be able to conduct much more in depth analyses of cell lineage in early embryonic development. Faculty Supervisor: Stanley K. Sessions
The Effects of Thalidomide, an Angiogenesis Inhibitor, on the Estrus Cycle and Reproductive Function of Female Mice. ASHLEY DOCKENDORFF, Department of Biology, Hartwick College, Oneonta, NY 13820. Thalidomide is an angiogenesis inhibiting drug that is being investigated as a possible treatment for various cancers and diseases. The effect that thalidomide could have on normal processes in the body that involve angiogenesis, such as the reproductive cycle of females, is not fully known. The purpose of this study was to observe and determine the effect of various dosages of thalidomide on the reproductive system of female mice. Thalidomide was administered at 0 mg/kg, 60 mg/kg, 180 mg/kg, and 560 mg/kg for 20 days. During this time, the duration of the estrus cycle and stages was assessed. Subsequent to euthanization, the ovaries and uterus were extracted, processed with zinc fixative, and embedded in paraffin wax. Immunohistochemistry, using monoclonal antibodies that target platelet endothelial cell adhesion molecule (PECAM-1), was performed to visualize the endothelial cells of the blood vessels. The dimensions of the organs were analyzed and the blood vessel density was compared using ImagePro software. A significant difference (p = 0.002) in days spent in estrus in the first half of treatment versus the second half of treatment was noted for the high dose treatment group, but not for the other treatment groups. No significant differences were found in the dimensions of the organs or blood vessel density between the different treatment groups. Faculty Supervisor: Dr. Laura Gray Malloy
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Anthelmintic effect of Tamarindus indica against Strongyloides stercoralis in vitro. AIMEE DOYLE, Department of Biology, Hartwick College, Oneonta, NY 13820. This study assessed the anthelmintic activity of Tamarindus indica against Strongyloides stercoralis eggs in vitro compared it to that of Albendazole, a pharmaceutical reference drug. Seven T. indica treatment groups were established from seven different extract dosages: 2x10-7 g/ml, 2x10-6 g/ml, 2x10-5 g/ml, 2x10-4 g/ml, 2x10-3 g/ml, 2x10-2 g/ml and 2x10-1 g/ml. Two additional groups of Strongyloides eggs were treated with Albendazole at dosages of 4.4x10-3 g/ml and 7.2x10-3g/ml. A non-treated group consisted of Strongyloides eggs in distilled water and served as the control. The eggs in each group were incubated at 25o for two days to promote hatching. Egg development was then analyzed under 400x magnification. The percentage of hatched larvae and the percentage of viability of both the larvae and the eggs were calculated for each group. Faculty supervisor: Dr. Linda Swift.
Extra-pair Paternity in Veeries. ELIZABETH ENTWISTLE, Hartwick College, Oneonta, New York. Although most species of birds are socially monogamous, 86% of passerines in which paternity has been examined exhibit some level of extra-pair paternity (Rowe et al. 2001). Extra-pair paternity is important in understanding the reproduction and life-history strategy of a species. I examined extra-pair paternity in Veeries (Catharus fuscescens) using 4 microsatellite markers developed by Gibbs et al. 1999 for Swainson’s thrush (Catharus ustalatus), a close relative of the Veery. I used 2 individuals to determine that these 4 primers successfully amplify in Veeries. Using the primer for the Cum 04 locus in Swainson’s thrush, I successfully amplified microsatellites in 44 individuals from 9 families. To date, I have successfully run one of these families on a polyacrylamide gel to determine polymorphism. Individuals showed polymorphism at this locus indicating that these primers can be used to study extra-pair paternity. Faculty Supervisor: Dr. Peter Fauth
The Effects of the Chemical Pollutant Atrazine on Parasite Infection in Frogs. AMANDA FISHER, Biology Department, Hartwick College, Oneonta, NY. It is now known that many, if not most cases of amphibians with deformed limbs are caused by a trematode parasite, and it is known that the deformities are caused by mechanical perturbation of development. But why the deformed frogs are showing up so much in recent times is still a puzzle. It has been proposed that amphibians are becoming more susceptible to the parasite because of an increase in pollution. It is thought that pollution is weakening the immune system of amphibians, making it easier for the trematode to infect them. But if the pollution is affecting the amphibians wouldn’t it also affect the trematodes? My study focused on the effects of atrazine, a widespread environmental pollutant, on the ability of trematodes to infect tadpoles. Tadpoles at early stages of limb development were exposed to trematode-infected snails that release trematode larvae known to infect amphibians. The exposures were conducted at different concentrations of atrazine as well as controls with no atrazine. After 24 hours the tadpoles were removed and examined for Ribeiroia cysts in order to compare infection rates. The results show differences in infection rates at different concentrations, but these were not statistically significant. Faculty Supervisor: Dr. Stanley Sessions
Could Atrazine Affect the Immune System of the Frog, Rana pipens? AMANDA HOUCK, Department of Biology, Hartwick College, Oneonta, NY 13820. Reports of declining and deformed amphibians have been increasing in the last few years and this issue has become one of the top environmental problems of the last decade. It is now known that this problem involves various infectious pathogens, including chytrid fungi and parastic flatworms (trematodes). A possible explanation for this growing problem is that something in the environment is affecting amphibian immune systems. This is an important problem because frogs and humans have similar immune systems and frogs are considered an indicator species because their thin skin and dependence on water makes them particularly susceptible to chemical pollutants from the surrounding environment. Atrazine is the most widely used herbicide in North America and has been detected as a common environmental pollutant. The purpose of this research was to test the idea that low concentrations of atrazine may have an effect on the immune systems of amphibians, rendering them more susceptible to pathogen infection. Faculty supervisor: Dr. Stanley K. Sessions
The Effects of Quinine on Saliva pH After Exercise. JONATHAN HUDAK, Biology Department, Hartwick College, Oneonta, NY. The purpose of this study was to determine the effects on tonic water on pH after cardiovascular exercise. Tonic water contains quinine, an alkaloid substance found in the bark of cinchona trees. The study evaluated saliva pH in seven college-aged males. Tonic water could be a useful buffering agent in the blood as a result of the basic properties of quinine. Quinine is absorbed quickly and fairly completely, only 20% of quinine is excreted (United States Pharmacopeias). The composition of saliva contains about two to three times the bicarbonate that is found in plasma, making it a buffering agent when blood or gastric pH becomes acidic (Guyton 348, 741). Preliminary tests using narrow range pH paper showed significant changes towards acidic saliva after intense exercise, reinforcing the idea of salivary buffering capacity. Each of three treatment conditions (water, PowerAde, and tonic water) were administered to the same individuals. To test the hydration state of the seven subjects, pH samples of saliva were taken before, and at each minute following exercise for 5 minutes, and finally after 10 minutes a final measurement was taken. Heart rate was also measured at each time interval to go along with a qualitative questionnaire. There appeared to be no significant difference between the overall results of the treatments, however there were some differences at specific time points during the treatment that might suggest improved pH buffering with tonic water. Faculty Supervisor: Dr. Laura Malloy
Muscle Contraction and Post-Injury Regeneration and Rehabilitation. BRAD HUFFAKER, Chemistry Department, Hartwick College, Oneonta, NY. The intentions of this project are to compare the methods of three approaches to soft tissue rehabilitation. Chiropractics, orthopedics, and physical therapy are three common practices that largely deal in rehabilitating muscles and the similar tissues found in tendons and ligaments. After a discussion of the processes that occur to cause a muscle to contract, the concepts mentioned were viewed in the context of the care that is provided by each of the aforementioned careers that deal with muscle-related injuries. Professionals from each field were interviewed to obtain information and insight: Dr. Ken Bell, an orthopedist with Maryville Orthopedic; Joe Black, a physical therapist and owner of Appalachian Therapy; Dr. Steven Watts, chiropractor and owner of Watts Chiropractic; and Dr. Eugene Runné, chiropractor and owner of Runné Chiropractic. Each professional was asked a series of questions regarding their personal views on soft tissue rehabilitation, their professional goals in regards to the theories and methods applied in their disciplines, and the various instruments and techniques they use, respectively, to treat a patient. It was found that the underlying theme from the answers provided is that muscle and related soft tissues heal most efficiently and effectively by using stretching in various forms to reduce scar tissue adhesions and restore blood flow to allow the body’s natural mechanisms to reform torn tissue connections. Faculty Advisor: Dr. Linda Swift
The Location of Antibiotic Resistance Genes in Bacteria Isolated from the Susquehanna River. DAVID MILLER, Department of Biology, Hartwick College, Oneonta NY 13820. Wastewater treatment outflows provide an influx of antibiotic resistant bacteria into aquatic environments. There is potential for gene exchange between pre-existing and newly introduced bacteria at outflow sites and in rivers as the bacteria are transported downstream. Gene transfer was investigated by comparing identities of antibiotic resistant coliform bacteria in culture collections whose source was Susquehanna River water collected at and 50 meters below the outflow pipe of a wastewater treatment facility. Twenty-eight bacteria were identified with the Biolog GN2 microplate system. At the outflow site there were five different genera of bacteria and seven different species. All species but one identified at the outflow site were also present at the downstream site. Several additional species were identified at the downstream site. The greater diversity of resistant bacteria found at the downstream site is evidence of gene exchange as bacteria are transported downstream. Antibiotic resistant bacteria present only at the downstream site include opportunistic human pathogens such as Kluyvera cryocrescens. Transformation experiments have shown that the antibiotic resistance genes are located mainly on plasmids allowing easy transfer of these genes. Faculty Supervisor: Dr. Mary Allen
Endocrine Disruptors in Amphibians and Mammals: Analysis of the Effect of Two Common Environmental Pollutants. CLARENCE OWENS, Hartwick College, Oneonta, NY. This study examined the effects of common environmental pollutants in amphibians (frogs of the genus Rana) and mammals (laboratory mouse, Mus musculus). The effects of the pesticide atrazine and the gasoline additive MTBE on growth, development, and sex differentiation were studied in frogs, and the effects on the immune system were examine in mice. Experimental methods included morphology, hematology, histology, and hemolytic plaque assays. Frogs were treated from the time of hatching to metamorphosis. Growth was determined by weight, and development was determined as percent reaching metamorphosis after a given amount of time. Sex differentiation was studied first by morphological examination of the gonads in newly metamorphosed frogs, and was then confirmed histologically. The mice were treated for three weeks, beginning at 16 weeks of age and the effect on their immune system was examined using the hemolytic plaque assay (HPA) to measure the number of activated (antibody-producing) B-lymphocytes. Results show that atrazine has a large but negative impact on growth and development, but no discernable effect on sex differentiation in frogs. MTBE (methyl-tertiary-butyl-ether), a gasoline additive, has little or no effect on growth and development in frogs, but appears to have a pronounced effect on sex differentiation. The effects of contaminants on the immune system in mice are equivocal, but other, unexpected detrimental effects were observed. These results suggest that atrazine and MTBE are both environmental toxins and may act as endocrine disruptors with variable effects on amphibians and mammals. These chemical contaminants may therefore be playing a role in amphibian declines and could also pose hazards for human health. Faculty Supervisor: Dr. Stanley Sessions
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Heating Skin Temperatures in the Arm Causes Increased Nerve Conduction Velocities. ERIC SAXTON, Biology Department, Hartwick College, Oneonta, NY. Post-polio patients begin to lose motor function many years after initial onset of the poliomyelitis disease. This is generally attributed to the aging of the remaining functional motor neurons that carry action potentials to the skeletal muscle. These motor neurons take on a greater load over a lifetime after polio damaged neurons have failed. Some patients also suffer from ‘cold limb’, which is the deterioration of core temperature in affected limbs of post-polio patients This raises the possibility that alterations in tissue temperature are responsible for some or all of the loss of motor function. If this is the case, limb heating should restore motor function. One way to evaluate neural function is by measuring nerve conduction velocities (NCV). Nerve conduction velocities were measured in three different conditions: normal temperature, after a cooling of the arm similar to ‘cold-limb’, and after heating the arm. The results concluded that cooling of the arm did slow down conduction velocities, and heating the arm afterward did increase conduction velocities toward the control and sometimes faster. Heating of the arm did increase nerve conduction velocities, which could one day lead to possible treatments for the post-polio community. Faculty Supervisor: Dr. Laura Malloy
The Specificity and Sensitivity of an In-Office ELISA Test Kit for the Detection of Borrelia burgdorferi in Canines. CARRIE SCHMIDT, Department of Biology, Hartwick College, Oneonta, NY 13820. Lyme disease is the result of a bacterial infection from Borrelia burgdorferi, and it has become a growing problem in humans, as well as canines. In collaboration with Howes Cave Animal Hospital and the Animal Shelter of Schoharie Valley, blood samples were drawn from canine patients, and the serum collected and frozen until testing began. The serum was tested for the presence of B. burgdorferi antigens using an in-office ELISA test kit (Snap 3Dx, IDEXX Laboratories) and compared with information gathered from a standard ELISA analysis (Borrelia burgdorferi ELISA Canine IgG Antibody Detection, Helica Biosystems, Inc.) and a Western Blot analysis (QualiCode™ Canine Lyme Disease Kit, Immunetics), which may be positive due to previous vaccination, natural exposure or active disease. Due to disagreements in the data from the in-office ELISA and Western Blot analysis, the results indicate that the new technology provided by the Snap 3Dx test kit may not be entirely fool proof. Faculty Supervisors: Dr. Walter Nagel and Dr. Douglas Hamilton
Optimization of Techniques for Visualizing Variable Number of Tandem Repeat (VNTR) polymorphisms in a College Population. JODI SCHROTH, Department of Biology, Hartwick College, Oneonta, NY 13820. DNA fingerprinting is becoming the primary way of identifying and distinguishing between individuals and is a key laboratory practice taught in many freshman college courses. The purpose of this study was to optimize the methods used to visualize the VNTR polymorphisms used in one such class. Human chromosome one contains a VNTR locus called pMCT118 that has a repeating DNA unit of sixteen base pairs. Humans have between fourteen and forty copies of this repeat, therefore the target area to optimize is separation between the DNA bands located in the region between 200 and 700 base pairs. The sources of DNA were several DNA markers and DNA collected from a sample of students at Hartwick College by various methods. Agarose gels and acrylamide gels made at varying percentages were compared. Electrophoresis was used to separate the DNA. The gels were then stained using multiple methods and the DNA conformations were visualized by illumination on an ultraviolet light box. The gels and different staining techniques were evaluated to determine which method produced the “best” image, i.e. the gel with the thinnest and sharpest DNA bands and the most spatial separation. After several trials, the results suggest that the best collection of DNA is from cheek cells obtained by a vigorous rinse with a 0.9% saline mouth wash. The best DNA resolution was obtained with a 4% agarose gel stained with SYBR Gold® (Invitrogen, Carlsbad, CA). Thesis advisor: Dr. Douglas Hamilton
Effect of Beta-Hydroxy-Beta-Methylbutyrate (HMB) Supplementation and An HMG-CoA Inhibitor, Simvastatin, On Muscle Metabolism During Resistance Exercise Training On Mice. LAURA SHOCKRO, Department of Biology, Hartwick College, Oneonta, NY 13820. Some forms of muscle cell injury, including those found following resistance training, have been associated with decreasing muscle membrane integrity. It has been suggested that de novo synthesized cholesterol is used to sustain cell membrane integrity and aids in delaying muscle proteolysis. Thus, it is possible that the dietary supplement, HMB, because it can be converted to the cholesterol precursor molecule HMG-CoA, could delay muscle proteolysis by replenishing HMG-CoA in the de novo cholesterol synthesis pathway. If this hypothesis is correct, then inhibiting the production of HMG-CoA in the cholesterol synthesis pathway will prevent the beneficial effects of dietary supplement HMB. To test this hypothesis, Simvastatin, an HMG-CoA reductase-inhibiting drug, was used along with supplemental HMB in the daily diets of mice under a resistance-training regimen. Female Swiss Webster mice (n=16) were divided into two groups. The first group (n=7) was supplemented with .015g of HMB mixed in honey daily for 21 days. The second group (n=7) was supplemented with .015g HMB and 50kg/mg of Simvastatin mixed in honey for 21 days. The remaining two mice did not receive any dietary supplementation. Exercise protocol consisted of mice running on an increment-weighted wheel (week 1: 40g, week 2: 60g, week 3: 80g) 30 minutes daily for 21 days. The effect of each treatment on resistance exercise performance was evaluated by determining each mouse’s maximum capacity for weighted wheel rotation. Creatine phosphokinase and lactate dehydrogenase activities will also be measured to assess the muscle damage in each of the groups. Faculty supervisor: Dr. Laura G. Malloy
Effects of Antimicrobial Agents Found in Toothpastes and Mouthwashes on Mixed Species Oral Biofilms. LINDSEY THOMAS, Department of Biology, Hartwick College, Oneonta, NY 13820. Oral biofilms are made up of bacteria that attach to the enamel of the teeth and form plaques. These plaques cause dental caries or cavities, which can lead to periodontal disease. This study was designed to test the effects of toothpastes and mouthwashes, available over-the-counter and containing antimicrobial agents, on biofilms. To create biofilms, saliva collected from a donor who had gone 24 hours without oral hygiene was cultured with nutrient broth on chambered slides for 48 hours at 37°C. I cultured 5 slides for each toothpaste and mouthwash treatment. Following growth, each biofilm was treated, for the time specified in the antimicrobial product instructions, with one of the following antimicrobial agents: Aquafresh, Crest and Colgate were the toothpastes used and Scope, Crest and Listerine were the mouthwashes. Controls were treated with water and treated and biofilm controls were rinsed at the end with water. LIVE/DEAD BacLight (Molecular Probes) fluorescent stain was applied to the biofilms for determination of total and dead cell quantities. The percent of live cells was compared among treatments using ANOVA followed by Tukey post-hoc tests to compare effects of individual products to the control. Biofilms treated with Aquafresh toothpaste had significantly (p= 0.001) more cells than control biofilms, while Crest and Colgate treatments had no significant effects (p> 0.05). Similarly, none of the mouthwashes had a significant effect on the quantity of live cells remaining in the biofilms (p> 0.05). These results suggest that the antimicrobial agent used in Aquafresh differs from that which is used in Crest and Colgate, either by the agent itself being different or possibly the same agent at a different concentration. This is in fact the case; it differs in the agent that is used in Crest, and a different concentration of the same agent is used in Colgate. In addition, the results suggest that the mouthwashes use similar active ingredients at similar concentrations, or possibly all use different agents that are ineffective. Out of the mouthwashes used, Scope and Crest used the same active ingredient, however it is not clear at what concentration Scope uses the agent. Listerine is composed of many different antimicrobials agents at various concentrations. Faculty Supervisor: Dr. Mary E. Allen