Kiralyn Brakel

As a result of the extensive use of atrazine in the 1960s, this herbicide has become the second most frequently used agrochemical in the United States. It effectively kills broad-leaf weeds and maintains commercial crops like corn, sorghum, and sugarcane. It can also be used to maintain residential lawns, sports fields, and playgrounds. However, due to its common use throughout the world, atrazine has been a frequent point of interest for agrochemical and environmental research. Atrazine has been shown to cause organ malformations, disrupt endocrine functions, and stunt growth in animals like birds, fish, rats, mice, rabbits, and amphibians. To further study atrazine’s detrimental impact on wildlife, this study examines caspase 3 as a measure of apoptosis, where programmed cell death is instigated by atrazine. This was done by exposing Xenopus laevis tadpoles to atrazine at concentrations of 0 μg/L, 21 μg/L, 200 μg/L, and 400 μg/L, and observing the fluorescence of the apoptotic marker caspase 3 as an indicator of the severity of apoptosis within the livers. Due to widespread mortality among all treatment groups, obtaining results that statistically showed a difference in severity of apoptosis was not achieved. Of the tadpole livers that were able to be sectioned, stained, and analyzed for caspase 3 fluorescence, there did not seem to be much of a difference in fluorescence across treatment groups. Additionally, images of the tadpole livers taken using a confocal microscope seem to coincide with the idea that there was not much of a difference in fluorescence.

This project also sampled different local water sources to examine the level of atrazine present. Samples were taken from four sites, three of which came from Michigan and one that came from Ohio. Due to the sampling technique for these water samples, statistics were not able to be done. However, after running an atrazine ELISA, the results suggest that there were lower amounts of atrazine prior to May, which is the typical time for atrazine application on farms, and high amounts of atrazine after May. The results also showed that atrazine levels were abundant in locations that did not apply atrazine in the year that we sampled. 

Atrazine is one of the most widely used herbicides in the United States because it is effective at mitigating broad leaf weeds and is easily broken down by crop plants. However, atrazine poses a significant ecological concern because it has been shown to be an endocrine disruptor in amphibian species. This research focused on the effects of atrazine exposure on adipocyte area and triglyceride content via the lipid membrane associated protein perilipin 1 to explain the metamorphic irregularities exhibited by Xenopus laevis tadpoles exposed to atrazine. Prior to tadpole husbandry, water samples were obtained from agricultural environments in Ohio and Michigan to determine environmentally relevant atrazine water concentrations. Xenopus laevis tadpoles were then exposed to various concentrations of atrazine and were measured for overall growth characteristics. Hematoxylin and eosin staining was performed to determine mean adipocyte area and fluorescent immunohistochemistry was performed to observe the fluorescence of perilipin 1. Mean adipocyte area and fluorescence were compared between the treatment groups using two sample t-tests to quantify the effects of atrazine. It was found that that while atrazine did not have a significant effect on adipocyte size, it did significantly impact perilipin 1 presence, which could be a potential biomarker for stunted or irregular tadpole maturation.