[Pharmwaste] FW: Estrogen Linked to Lowered Immunity in Fish

[Tenace, Laurie]

This release can be found in the USGS Newsroom at:
http://www.usgs.gov/newsroom/article.asp?ID=2228. 

 

News Release 

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June 3, 2009  

Laura Robertson  304-724-4579  lrobertson at usgs.gov  

Diane  Noserale  703-648-4333  dnoseral at usgs.gov  

 
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One Step Closer to Understanding Fish Health in Potomac and Shenandoah Rivers


Estrogen Linked to Lowered Immunity in Fish 

Exposure to estrogen reduces production of immune-related proteins in fish.
This suggests that certain compounds, known as endocrine disruptors, may make
fish more susceptible to disease. 

The research may provide new clues for why intersex fish, fish kills and fish
lesions often occur together in the Shenandoah and Potomac rivers. The tests
were conducted in a lab by scientists from the U.S. Geological Survey. 

The study, led by USGS genomics researcher Dr. Laura Robertson, revealed that
largemouth bass injected with estrogen produced lowered levels of hepcidin,
an important iron-regulating hormone in mammals that is also found in fish
and amphibians.  This is the first published study demonstrating control of
hepcidin by estrogen in any animal. 

Besides being an important iron-regulating hormone, researchers also suspect
that hepcidin may act as an antimicrobial peptide in mammals, fish and frogs.
Antimicrobial peptides are the first line of defense against disease-causing
bacteria and some fungi and viruses in vertebrate animals. 

"Our research suggests that estrogen-mimicking compounds may make fish more
susceptible to disease by blocking production of hepcidin and other
immune-related proteins that help protect fish against disease-causing
bacteria," said Robertson. 

USGS researchers Drs. Vicki Blazer and Luke Iwanowicz have previously found
intersex occurring in fish in the Potomac and Shenandoah rivers. Intersex is
primarily revealed in male fish that have immature female egg cells in their
testes. Because other studies have shown that estrogen and estrogen-mimicking
compounds can cause intersex, the co-occurrence of fish lesions, fish kills
and intersex in these two rivers suggested to USGS scientists that
estrogen-mimicking compounds could be involved in the fish lesions and fish
kills in addition to being a possible cause of intersex traits.  

That caused Robertson and her colleagues to investigate how estrogen could be
affecting the immune system in these fish.  The study showed that largemouth
bass produced two different hepcidin proteins.  Production of the first
hepcidin protein was "turned down" by estrogen.  Production of the second
hepcidin protein by fish exposed to bacteria was blocked by estrogen.  The
fact that estrogen blocked production of hepcidins in fish exposed to
bacteria gives more weight to the theory that estrogen or estrogen-mimicking
chemicals could be making fish more susceptible to diseases, Robertson added.


Hepcidin could protect against bacterial infection in two ways.  "First,"
said Robertson, "hepcidin could be an antimicrobial peptide that actually
kills pathogens. Or it could be more complex. To live, a microbe must have
iron, so when a microbe invades a person or animal, that microbe must obtain
iron from its host. To 'fight' the microbe, a host can 'suck up iron' and
store it in places inaccessible to the microbe. In mammals, hepcidin is a key
player in how the host takes up and stores iron." 

The study, Identification of centrarchid hepcidins and evidence that
17β-estradiol disrupts constitutive expression of hepcidin-1 and inducible
expression of hepcidin-2 in largemouth bass (Micropterus salmoides), was just
published in the journal, Fish & Shellfish Immunology. The authors are USGS
scientists Laura Robertson, Luke Iwanowicz and Jamie Marie Marranca. 

 

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Email:   Deborah.DeBiasi at deq.virginia.gov (NEW!)
WEB site address:  www.deq.virginia.gov
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