Effects of Metformin and its Metabolite Guanylurea on Fathead Minnow (Pimephales promelas) Reproduction.

Metformin, along with its biotransformation product guanylurea, is commonly observed in municipal wastewaters and subsequent surface waters. Previous studies in fish have identified metformin as a potential endocrine-active compound, but there are inconsistencies with regard to its effects. To further investigate the potential reproductive toxicity of metformin and guanylurea to fish, a series of experiments was performed with adult fathead minnows (Pimephales promelas).

Characterization of vitellogenin concentration in male fathead minnow mucus compared to plasma, and liver mRNA.

The objective of this study was to characterize vitellogenin (VTG) protein in male fathead minnow (Pimephales promelas) mucus compared with more conventional measures in plasma and mRNA isolated from liver. To assess the intensity and duration of changes in mucus VTG concentrations, male fathead minnows were exposed to 17α-ethinylestradiol (EE2) for 7 days with a subsequent depuration period of 14 days. The experiment was conducted in a flow-through system to maintain a consistent concentration of EE2 at a nominal EC concentration of 2.

De Novo Assembly of the Nearly Complete Fathead Minnow Reference Genome Reveals a Repetitive but Compact Genome.

The fathead minnow is a widely used model organism in environmental toxicology. The lack of a high-quality fathead minnow reference genome, however, has severely hampered its uses in toxicogenomics. We present the de novo assembly and annotation of the fathead minnow genome using long PacBio reads, Bionano and Hi-C scaffolding data, and large RNA-sequencing data sets from different tissues and life stages.

Multigene Biomarkers of Pyrethroid Exposure: Exploratory Experiments.

We describe initial development of microarray-based assays for detecting 4 pyrethroid pesticides (bifenthrin, cypermethrin, esfenvalerate, and permethrin) in water. To facilitate comparison of transcriptional responses with gross apical responses, we estimated concentration-mortality curves for these pyrethroids using flow-through exposures of newly hatched Daphnia magna, Pimephales promelas adults, and 24 h posthatch P. promelas.

Immunoprevalence to Six Waterborne Pathogens in Beachgoers at Boquerón Beach, Puerto Rico: Application of a Microsphere-Based Salivary Antibody Multiplex Immunoassay.

Waterborne infectious diseases are a major public health concern worldwide. Few methods have been established that are capable of measuring human exposure to multiple waterborne pathogens simultaneously using non-invasive samples such as saliva. Most current methods measure exposure to only one pathogen at a time, require large volumes of individual samples collected using invasive procedures, and are very labor intensive.

Initial development of a multigene 'omics-based exposure biomarker for pyrethroid pesticides.

Omics technologies have long since promised to address a number of long standing issues related to environmental regulation. Despite considerable resource investment, there are few examples where these tools have been adopted by the regulatory community, which is in part due to a focus of most studies on discovery rather than assay development. The current work describes the initial development of an omics based assay using 48h Pimephales promelas (FHM) larvae for identifying aquatic exposures to pyrethroid pesticides.

The development and implementation of a method using blue mussels (Mytilus spp.) as biosentinels of Cryptosporidium spp. and Toxoplasma gondii contamination in marine aquatic environments.

Surveillance monitoring for microbial water quality typically involves collecting single discrete grab samples for analyzing only one contaminant. While informative, current approaches suffer from poor recoveries and only provide a limited snapshot of the microbial contaminants only at the time of collection. To overcome these limitations, bivalves have been proposed as effective biosentinels of water quality particularly for their ability to efficiently concentrate and retain microbial contaminants for long periods of time.

Sensitivity of the vitellogenin assay to diagnose exposure of fathead minnows to 17α-ethynylestradiol.

Vitellogenin is frequently used as a biomarker of exposure to environmental estrogens due to its specificity and sensitivity. Appropriate incorporation of this biomarker into environmental monitoring and assessment necessitates evaluation of its critical performance parameters. In this study, we characterize the sensitivity of both vitellogenin gene (vtg) mRNA transcripts in liver and protein (VTG) in plasma over a range of concentrations and exposure durations.

Evaluation of four RNA extraction methods for gene expression analyses of Cryptosporidium parvum and Toxoplasma gondii oocysts.

Cryptosporidium spp. and Toxoplasma gondii are important coccidian parasites that have caused waterborne and foodborne disease outbreaks worldwide. Techniques like subtractive hybridization, microarrays, and quantitative reverse transcriptase real-time polymerase chain reaction (RT-qPCR) assays have been used to understand the roles of specific genes in regulating life stage development and pathogenesis of these parasites.

Evaluation of hollow-fiber ultrafiltration primary concentration of pathogens and secondary concentration of viruses from water.

Tangential flow hollow-fiber ultrafiltration (HFUF) was evaluated for virus and Cryptosporidium parvum concentration from water. Recovery of viruses at a low filtration rate was found to be significantly greater than at a higher filtration rate, with the recoveries of bacteriophage MS2 at high and low filtration rates shown to be 64.7% and 98.

Determining UV inactivation of Toxoplasma gondii oocysts by using cell culture and a mouse bioassay.

The effect of UV exposure on Toxoplasma gondii oocysts has not been completely defined for use in water disinfection. This study evaluated UV-irradiated oocysts by three assays: a SCID mouse bioassay, an in vitro T. gondii oocyst plaque (TOP) assay, and a quantitative reverse transcriptase real-time PCR (RT-qPCR) assay.

Using quantitative reverse transcriptase PCR and cell culture plaque assays to determine resistance of Toxoplasma gondii oocysts to chemical sanitizers.

Toxoplasma gondii oocysts are highly resistant to many chemical sanitizers. Methods used to determine oocyst infectivity have relied primarily on mouse, chicken, and feline bioassays. Although considered gold standards, they only provide a qualitative assessment of oocyst viability.

Obtaining highly purified Toxoplasma gondii oocysts by a discontinuous cesium chloride gradient.

Toxoplasma gondii is an obligate intracellular protozoan pathogen that commonly infects humans. It is a well characterized apicomplexan associated with causing food- and water-borne disease outbreaks. The definitive host is the feline species where sexual replication occurs resulting in the development of the highly infectious and environmentally resistant oocyst.