March 20, 2015

Endocrine disrupting chemicals and their effects on the reproduction of eastern mosquitofish

Kayla Skoglund '15

Endocrine disrupting chemicals are pollutants in the environment and can have detrimental effects on both humans and wildlife. They are known for interfering with the endocrine functions of the organism at very low concentrations. In the paper, An Androgenic Agricultual Contaminant Impairs Female Reproductive Behavior in a Freshwater Fish (Saaristo et al. 2013), they investigated the effects of short term exposure to trenbolone (17B-trenbolone), which is used as a growth promoter for cattle, on the reproductive behavior and fin morphology of the eastern mosquitofish (Gambusia holbrooki). Mosquitofish are livebearers in which males inseminate females using a modified anal fin, but the females have some say as to how successful the males are by selectively associating with certain males. Male and female mosquitofish were exposed to an environmentally relevant dose of 6 ng/L of 17B-trenbolone and behavior was monitored. The findings show that the male fish had no difference in behavior whether exposed or not, while the female spent more time swimming away from the males when exposed to trenbolone. This study is the first of its kind to show that exposure to an androgenic EDC, like trenbolone, has detrimental effects on females but not males in their reproductive behavior.

ACTN3 gene and it's association to endurance alleles in athletes compared to survival alleles in centenarians

Georgia Korsah '15

The interaction of the genotype and the environment shows that exercise phenotypes take part inestablishing a survival trait. It is believed that exercise phenotypes are associated with exceptional survival in the centenarian population. The main purpose of the study was to compare genotypic frequency of the ACTN3 R577X polymorphism between centenarians and a group of healthy young adults. Another aim was to compare the data obtained in centenarians with the two groups of humans who show the two extreme phenotypes of the exercise performance continuum, elite athletes prevailing in endurance and power sports. One of the study’s hypotheses was that the ACTN3 R577X allelic/genotypic frequency distribution of centenarians is similar to that of endurance athletes. Although there were no differences in genotype/allele frequencies between centenarians, and controls or endurance athletes, they observed a significantly higher frequency of the X allele (P = 0.019) and XX genotype (P = 0.011) in centenarians compared with power athletes. In conclusion, there were no significant differences with the control group of young adults, overall the ACTN3 genotype of centenarians resembles that of world-class elite endurance athletes and differs from that of elite power athletes. The data suggests a certain ‘survival’ advantage from the a-actinin-3 deficiency and the ‘endurance’/oxidative muscle phenotype that is commonly associated with this condition (Fiuza-Luces et al., 2011).

Epidemiological tracing of a new food vehicle for Salmonella: Salmonella Tennessee outbreak from peanut butter

Dunia Dadi '15

Foodborne illnesses affect as many as 1 in 6 Americans each year and outbreaks are a major public health concern that require effective prevention and surveillance strategies as proper control measures. However, every foodborne outbreak can not be treated the same, as there are many possible causative agents (bacteria, viruses, parasites and toxins) and various food vehicles that can be responsible for illness. Tracing such food vehicles can be a difficult task ,especially, if cases have not been linked to certain products previously. In the paper by Sheth et al. ,they conducted a case-control study in 22 states to investigate the food source of a multistate outbreak of Salmonella Tennessee. They interviewed 65 cases, who were confirmed with 1 of 3 outbreak strain types and experienced onset of symptoms from August 1 2006, and controls ,who did not have symptoms and were matched to cases by geographic location. Findings from initial investigation followed by the case-control study identified an association between illness with consuming Brand X and Brand Y peanut butter. Brands X and Y were produced in the same facility and distributed by a single company. Microbiological sampling from peanut butter and production plant environment confirmed these findings. Brand X and Y products were recalled on February 14, 2007, and cases of S. Tennessee substantially declined. This was also the first Salmonella outbreak in the U.S. associated with peanut butter. This study suggests that Salmonella can be linked to new food sources. Heat processed foods that use to be considered safer can be contaminated with Salmonella through heterogeneous roasting processes, cross-contamination and post processing contamination, which calls for improved national food safety protocols.