Sea lamprey research sheds light on how stress hormones evolved

Jul 19, 2010
Weiming Li, Michigan State University professor of fisheries and wildlife, holds a lamprey in his lab in East Lansing, Mich. Credit: Kurt Stepnitz, MSU University Relations

Michigan State University researchers are the first to identify a stress hormone in the sea lamprey, using the 500 million-year-old species as a model to understand the evolution of the endocrine system.

Corticosteroid hormones control stress response in animals with backbones, including humans. While scientists have learned quite a bit about these so-called in most modern animals, little was known about the hormones' earliest forms in prehistoric creatures such as lamprey.

"By identifying 11-deoxycortisol as a stress hormone in lamprey, it allows us to better understand how the endocrine system in vertebrates evolved into the complex systems we see in humans today," explained Weiming Li, professor of fisheries and wildlife who helped lead the project. Li also is a member of the Michigan Agricultural Experiment Station.

The hormone is the only one the researchers have found so far in the lamprey and Li said the researchers are hypothesizing that it may be the only corticosteroid hormone in the lamprey. Humans, in contrast, have more than 30 corticosteroid hormones.

The research is published in the July 19 edition of the .

Native to the Atlantic Ocean, sea lampreys are invasive species in the Great Lakes. They stay alive by attaching themselves to other fish, such as salmon and trout, and then suck out the fish's body fluids. One sea lamprey can kill 40 or more pounds of fish. The U.S. and Canadian governments spend about $10 million to $15 million per year on lamprey control.

Li led the groundbreaking research that identified the pheromone male lampreys use to attract females to their nests to mate. He has made a synthetic version of the pheromone and is testing its effectiveness as a control for the destructive parasites. While the identification of 11-deoxycortisol likely won't directly help his lamprey control work, Li said this new discovery will bolster understanding on how the fish has successfully adapted since the Paleozoic Era.

"Most jawless animals similar to the lamprey didn't survive into the modern era, so they're not available for us to use as we strive to learn more about how human systems developed," Li said. "The , a survivor, gives us a snapshot of what happened as vertebrates evolved into the animals we know today."

Li and his team plan to continue studying the lamprey, possibly investigating how the endocrine and other body systems became more integrated and successfully adapted to the changing environment.

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kevinrtrs
1 / 5 (2) Jul 20, 2010
using the 500 million-year-old species as a model to understand the evolution

I question the validity of the 500 ma statement here. There is no conclusive undisputed proof that the lamprey is that old. If it were that old surely there would have been other evolvement of the creature by now. Why would it stay the same as it was s o long ago? Further, why is it valid to assume that any evolution[if it were possible] of the lamprey led necessarily to anything even remotely linked to human beings?
I see this as simply wishful thinking.
Ethelred
5 / 5 (1) Jul 20, 2010
I question the validity of the 500 ma statement here
For once we agree. Though I suspect you and I disagree on the age of lampreys by several orders of magnitude.
If it were that old surely there would have been other evolvement of the creature by now
Certainly. However some species have not changed much in gross structure in quite a long time.
Why would it stay the same as it was s o long ago
If it actually did do that the reason would be that the environment had changed little.
lamprey led necessarily to anything even remotely linked to human beings
Because the earliest fish were jawless and lampreys are jawless. Something a bit like lampreys were ancestral to the later fish that left the water and became amphibians.
I see this as simply wishful thinking.
I see it as an interesting path that should be explored even if the modern lampreys aren't that close to early jawless fish.

Maybe 500MY isn't wrong.

http://www.lookd....ion.html

Ethelred
shavera
not rated yet Jul 20, 2010
@kevinrtrs: I think there's a common fault that people make when reading about things like this. It isn't that the lamprey as a species is 500MY old, but that in those 500MY there's been a branch of the jawless fish line that hasn't had much need to change its physiological plan much. There are parallels in plants (ginko), invertebrates (horseshoe crabs), other fish (coelocanth). It's not so much that ginko trees have never changed, merely that their body plan was sufficient for their place in ecology that they haven't had much need to change.
Ethelred
not rated yet Jul 20, 2010
I don't think kevinrtrs has that fault. He has a problem with pretty much any statement that might portend a world older than about 7,000 years.

Ethelred