CERC Branch: Biochemistry / Physiology

National Geographic films Biochemistry Branch on the Missouri RiverThe Biochemistry/Physiology Branch conducts basic and applied research at the cellular, organ, organism and population levels in fish and wildlife. Emphasis is on the sublethal effects of chemicals that lead to behavioral, developmental and population changes that may ultimately influence ecosystem health.

Research focus includes reproductive, developmental and neurotoxic effects of stressors. Scientists develop and use molecular, genomic, biochemical and histological analyses to evaluate mechanisms of toxicity, and conduct forensic field investigations.

Current studies in the Biochemistry/Physiology Branch include the use of DNA microarray technology to study endocrine disruptor mechanisms of action, mechanisms of intersex development in adult fish, definition of gene expression profiles for contaminants with diverse modes of action, effects of thiamine deficiency on early life stage mortality in salmonines, and effects of methylmercury on reproduction.




In The News

  • Missouri River Researcher to Discuss How Estrogen-like Chemicals Affect Sturgeon
    Monday, July 08, 2013
  • What Is Farm Runoff Doing To The Water? Scientists Wade In
    Friday, July 05, 2013
  • Human Hormones Hamper Aquatic Wildlife
    Friday, July 05, 2013
  • Feminized Fish: A Side Effect of Emerging Contaminants
    Thursday, September 13, 2012
  • PCBs Eating Away at Turtles
    Wednesday, November 23, 2011
    Chemicals (PCBs) that have lingered in the environment for decades may be eating away at the bones of turtles, and maybe, us. PCBs, once commonly used in pesticides and a wide variety of industrial fluids, have been banned for decades. But with very slow breakdown times, they are still widespread in the environment, particularly in more developed areas.  Read More
  • Are They Boy or Girl Fish? It’s Now Harder to Tell
    Tuesday, January 11, 2011
    According to the US Geological Survey, intersex, the presence of both male and female characteristics within the same fish, is being observed in fish in more streams across the nation. Intersex is one manifestation of endocrine disruption in fish, which can also result in adverse effects on the development of the brain and nervous system, the growth and function of the reproductive system, and the response to stressors in the environment.  Read More
  • Is Your Birth Control Making Male Fish Sprout Ovaries?
    Wednesday, December 08, 2010
    Ecologists keep tabs on sturgeon, a prehistoric fish that likes the Missouri River's muddy waters. The pallid sturgeon and the lake sturgeon are endangered, and the more common shovelnose sturgeon has become "a species of concern."  Read More
  • Columbia Researchers Study Intersex Sturgeon in Missouri River
    Tuesday, December 07, 2010
    Ecologist Aaron DeLonay, with the U.S. Geological Survey, holds a shovelnose sturgeon netted just east of Jefferson City on the Missouri River that he estimates to be 3 or 4 years old Oct. 29. DeLonay and a small team of scientists go out on the river frequently to check on the reproductive condition of a more rare fish, the pallid sturgeon, to see, and in some cases ensure, successful reproduction. Whenever DeLonay and his team catch a pallid sturgeon that they have not caught before, they implant a tracking device that, other than tracking water depth and temperature, can be used to determine if the fish mated.  Read More
  • Rise of the She-Fish?
    Wednesday, August 25, 2010
    Scientists want to know if Rio Grande contaminants are feminizing the endangered silvery minnow.  Read More
  • EPA, Stay Focused! Email Spats Don't Change the Science on Atrazine - It's Bad!
    Tuesday, August 24, 2010
    The EPA and USGS have found this chemical in almost every waterway where they have looked for it, and USGS even identified an association between contaminated streams and impaired fish reproduction. Our report also features a rundown of the most current science on the health impact of the pesticide, which references the work of Hayes’ lab that has been published in the peer-reviewed scientific journals, along with the published research of dozens of other scientists that all provide evidence of atrazine’s harms.  Read More
  • Common Herbicide is Harmful to Fish
    Friday, June 25, 2010
    The study was conducted by Donald Tillitt and a team of researchers at the Environmental Research Center in Columbia. The team exposed fathead minnows Pimephales promelas to levels of atrazine varying from 0-50 micrograms - all below the 'USEPA Office of Pesticides Aquatic Life Benchmark' of 65 micrograms per litre for chronic exposure of fish.  Read More
  • Work Shows Atrazine’s Potential Harm
    Sunday, May 30, 2010
    In an unrelated study, Don Tillitt, a research chemist at the U.S. Geological Survey’s Columbia Environmental Research Center, found that fathead minnows exposed to Atrazine produce fewer eggs and spawn less often than control groups. The study is one of the first to suggest that Atrazine can be harmful to fish at levels far lower than the benchmarks set by the Environmental Protection Agency.  Read More
  • Study Finds Atrazine Exposure Impairs Fish Reproduction
    Thursday, May 20, 2010
    Now researchers with the United States Geological Survey have shown that atrazine exposure can also lower fish reproduction and cause abnormalities in fish reproductive organs.  Read More
  • Commonly Used Atrazine Herbicide Adversely Affects Fish Reproduction
    Thursday, May 20, 2010
    Fathead minnows were exposed to atrazine at the USGS Columbia Environmental Research Centre in Columbia, Mo., and observed for effects on egg production, tissue abnormalities and hormone levels. Fish were exposed to concentrations ranging from zero to 50 micrograms per litre of atrazine for up to 30 days. All tested levels of exposure are less than the USEPA Office of Pesticides Aquatic Life Benchmark of 65 micrograms per litre for chronic exposure of fish. Thus, substantial reproductive effects were observed in this study at concentrations below the USEPA water-quality guideline.  Read More
  • New Study Finds Weed Killer Hurts Fish Spawning
    Wednesday, May 19, 2010
    USGS scientists, in a study published in the journal Aquatic Toxicology, reported that fathead minnows did not spawn as much or as well when exposed in the laboratory to concentrations of the pesticide below what's found in the wild. Exposed fish produced fewer eggs, and researchers observed abnormalities in reproductive tissues of exposed males and females.  Read More
  • Commonly Used Atrazine Herbicide Adversely Affects Fish Reproduction
    Wednesday, May 19, 2010
    Atrazine, one of the most commonly used herbicides in the world, has been shown to affect reproduction of fish, according to a new U.S. Geological Survey (USGS) study.  Read More
  • Common Herbicide Atrazine Affects Fish Reproduction
    Wednesday, May 19, 2010
    The farm herbicide atrazine, used widely worldwide, has been shown to affect reproduction in fish, according to a US government study released Wednesday.  Read More
  • Atrazine Affects Fish Reproduction
    Wednesday, May 19, 2010
    "Concentrations of atrazine commonly found in agricultural streams and rivers caused reduced reproduction and spawning, as well as tissue abnormalities in laboratory studies with fish," said USGS scientist Donald Tillitt, who led the research.  Read More
  • Pharmed Fish
    Thursday, April 01, 2010
    In the Spring issue of Trout, a quarterly magazine of Trout Unlimited, is a feature story, "Pharmed Fish: Are Pharmaceuticals and Other Pollutants to Blame for Alarming Numbers of Intersex Fish?", highlighting USGS fish health research by Jo Ellen Hinck, conducted over a 10-year period across nine U.S. river basins, the Nation's first comprehensive look at fish health including the intersex condition.  Read More
  • Something Fishy in the Water
    Wednesday, November 25, 2009
    Dean Reynolds, Correspondent: "Something strange is happening to the fish in America's rivers, lakes and ponds. Chemical pollution seems to be disrupting their hormones, blurring the line between male and female."  text  Read More
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