Nuclear characteristics of cells and organisms exposed to agrochemicals contaminating aquatic ecosystems

As modern agriculture has become more reliant on herbicides for weed management an increase in these chemicals contaminating aquatic ecosystems has occurred. The potential consequences of herbicide exposure to non-target organisms are not completely known. The main objective of these studies was to investigate the effects of herbicides reported to contaminate waterways and to evaluate the impacts of the herbicide contaminants using nuclear endpoints.; One initial concern is that in most laboratory studies the pure technical form of the herbicides are used in experimental analysis whereas the field grade formulations are what the organisms in the environment are exposed. A cellular in vitro test system was used to determine the concentrations at which cytotoxicity occurred. No differences were found between the technical and field grade formulations. As a result the technical grade herbicides were used in the remaining studies. The next step was to evaluate the cytotoxicity and impacts on the cell cycle of herbicide contaminants in comparison to aquatic herbicides registered for use in the aquatic environment. The herbicide contaminants were found to be no more cytotoxic or to cause no greater alterations to the cell cycle than the aquatic management herbicides utilizing the in vitro test system.; One current concern of the scientific community is the documented amphibian declines. Chemical herbicide contamination is one of the suspected contributing factors. The egg and larval stages of most amphibians occur in the water and as a result amidst chemical contamination. The potential effects of one of the most common herbicide contaminants, atrazine, were further investigated on non-target organisms in anurans. The genotoxicity and impacts on metamorphing anuran larvae were explored in two species. Atrazine was found not to be genotoxic to either species, but differential effects on development dependent upon the nuclear characteristics of metamorphosis were observed.; The final objective was to adapt a recently developed cytogenetic technique for use in anurans. The primed in situ labeling (PRINS) technique was applied to localize a specific developmentally important DNA sequence in anuran chromosomes. This technique has the potential to be an important tool in assessing developmental nuclear changes in metamorphing anurans.