Herbicides in aquatic environments: When the frog prince becomes the frog princess
Advisor Information
Alan Kolok
Location
UNO Criss Library, Room 232
Presentation Type
Oral Presentation
Start Date
7-3-2014 9:30 AM
End Date
7-3-2014 9:45 AM
Abstract
Herbicides used in row-crop agriculture can enter watersheds through runoff where exposed aquatic organisms may experience endocrine disrupting effects such as altered sexual reproduction and development. Atrazine (ATZ) is one of the most commonly used herbicides in Nebraska and has been suggested to alter male frog sexual development resulting in feminized male frogs. In 2012, male northern leopard frogs (Rana pipiens) were exposed to Elkhorn River water during a pulse of herbicide runoff during which atrazine was the primary herbicide detected. Following a 7 day exposure, frogs were feminized as indicated by the significant increase in mRNA expression of the estrogen responsive gene, estrogen receptor-alpha (ERα). The objective of this experiment was to determine if water spiked with atrazine at three concentrations (0.5 μg/L, 5.0μg/L, or 50.0 μg/L ATZ) would result in gene expression responses in male northern leopard frogs similar to those observed in frogs exposed to Elkhorn River water. Following a 7 day lab exposure, the impact of ATZ was assessed by measuring the mRNA expression of two estrogen responsive genes, vitellogenin (Vtg) and estrogen receptor-α (ERα) in liver tissues. Quantitative real-time PCR revealed that frogs exposed to 50.0 μg/L ATZ were feminized as indicated by the significant increase in ERα mRNA expression. This response was similar the response observed in male frogs exposed to Elkhorn River water. These results suggest that male northern leopard frogs may be particularly at risk during peak runoff periods in the spring when concentrations of ATZ may reach or exceed 50.0 μg/L.
Herbicides in aquatic environments: When the frog prince becomes the frog princess
UNO Criss Library, Room 232
Herbicides used in row-crop agriculture can enter watersheds through runoff where exposed aquatic organisms may experience endocrine disrupting effects such as altered sexual reproduction and development. Atrazine (ATZ) is one of the most commonly used herbicides in Nebraska and has been suggested to alter male frog sexual development resulting in feminized male frogs. In 2012, male northern leopard frogs (Rana pipiens) were exposed to Elkhorn River water during a pulse of herbicide runoff during which atrazine was the primary herbicide detected. Following a 7 day exposure, frogs were feminized as indicated by the significant increase in mRNA expression of the estrogen responsive gene, estrogen receptor-alpha (ERα). The objective of this experiment was to determine if water spiked with atrazine at three concentrations (0.5 μg/L, 5.0μg/L, or 50.0 μg/L ATZ) would result in gene expression responses in male northern leopard frogs similar to those observed in frogs exposed to Elkhorn River water. Following a 7 day lab exposure, the impact of ATZ was assessed by measuring the mRNA expression of two estrogen responsive genes, vitellogenin (Vtg) and estrogen receptor-α (ERα) in liver tissues. Quantitative real-time PCR revealed that frogs exposed to 50.0 μg/L ATZ were feminized as indicated by the significant increase in ERα mRNA expression. This response was similar the response observed in male frogs exposed to Elkhorn River water. These results suggest that male northern leopard frogs may be particularly at risk during peak runoff periods in the spring when concentrations of ATZ may reach or exceed 50.0 μg/L.