Posted on 09/13/2007 12:07:15 PM PDT by decimon
WASHINGTON - Papa salmon plus mama salmon equals ... baby trout? Japanese researchers put a new spin on surrogate parenting as they engineered one fish species to produce another, in a quest to preserve endangered fish.
Idaho scientists begin the next big step next month, trying to produce a type of salmon highly endangered in that state — the sockeye — this time using more plentiful trout as surrogate parents.
The new method is "one of the best things that has happened in a long time in bringing something new into conservation biology," said University of Idaho zoology professor Joseph Cloud, who is leading the U.S. government-funded sockeye project.
The Tokyo University inventors dubbed their method "surrogate broodstocking." They injected newly hatched but sterile Asian masu salmon with sperm-growing cells from rainbow trout — and watched the salmon grow up to produce trout.
The striking success, published in Friday's edition of the journal Science, is capturing the attention of conservation specialists, who say new techniques are badly needed. Captive breeding of endangered fish is difficult, and attempts to freeze fish eggs for posterity so far have failed.
"They showed nicely that ... they produced the fish they were shooting for," said John Waldman, a fisheries biologist at Queens College in New York.
"Future work should look to expand this approach to other fishes in need of conservation, in particular, the sturgeons and paddlefish," he added. "We have a lot of species of fish around the world that are really in danger of becoming extinct."
The Japanese researchers' ultimate goal: Boost the rapidly dwindling population of bluefin tuna, a species prized in a country famed for its tuna appetite.
"We need to rescue them somehow," said Goro Yoshizaki, a Tokyo University marine scientist who is leading the research.
First, Yoshizaki's team started with "salmonids," a family that includes both salmon and trout, and one of concern to biologists because several species are endangered or extinct.
Initial attempts to transplant sperm-producing cells into normal masu salmon mostly produced hybrids of the two species that didn't survive.
This time, Yoshizaki engineered salmon to be sterile. He then injected newly hatched salmon with stem cells destined to grow into sperm that he had culled from male rainbow trout.
Once they were grown, 10 of 29 male salmon who got the injections produced trout sperm, called milt.
Here's the bigger surprise: Injecting the male cells into female salmon sometimes worked, too, prompting five female salmon to ovulate trout eggs. That's a scientific first, Yoshizaki said.
The stem cells were still primitive enough to switch gears from sperm-producers to egg-producers when they wound up inside female organs, explained Idaho's Cloud.
Then Yoshizaki used the salmon-grown trout sperm to fertilize both wild trout eggs and the salmon-grown trout eggs. DNA testing confirmed that all of the dozens of resulting baby fish were pure trout, he reported.
Moreover, those new trout grew up able to reproduce.
Those first experiments, funded by a Japanese research institute, used still fairly plentiful species to develop the technique. Now comes Idaho's attempt to prove if the method is really useful in trying to produce the endangered sockeye salmon.
Last January, Yoshizaki helped University of Idaho scientists collect and freeze immature sperm tissue from young sockeye salmon being raised at a state-run hatchery. Next month, he'll be back to help Cloud thaw the tissue and implant it into sterile rainbow trout.
In Japan, Yoshizaki is focused on bluefin tuna, noting that standard "marine ranching" techniques are difficult for tuna that can reach man-size.
He has begun experiments into how to produce baby tuna from mackerel, which are nearly a thousand times smaller than adult tuna. If it works, "we can save space, cost and labor," he predicted in an e-mail interview.
Fairly bizarre story.
bump
Dr. Venkman: This city is headed for a disaster of biblical proportions.
Mayor: What do you mean, "biblical"?
Dr Stantz: What he means is Old Testament, Mr. Mayor, real wrath-of-God type stuff.
Dr. Venkman: Exactly.
Dr Stantz: Fire and brimstone coming down from the skies. Rivers and seas boiling.
Dr. Spengler: Forty years of darkness. Earthquakes, volcanoes...
Winston: The dead rising from the grave.
Dr. Venkman: Human sacrifice, dogs and cats living together - mass hysteria.
And that's no fluke.
This is against God and man. But apart from that, it’s pretty cool.
Mmmmmmm....crank up the grill and get me some cracked pepper and a couple of lemon wedges.
Didn't mean to start a religious roe.
Is it just me or does anyone else get a sick kind of "I've been kicked in the groin" feeling over this? It just doesn't seem fair/right.
Not like getting kicked by a mule. Or a gelding.
How agri-corporations around the world would treat their cows.
NORTH AMERICAN CORPORATION: You have two cows. You sell one, and force the other to produce the milk of four cows. You are surprised when the cow drops dead.
FRENCH: You have two cows. You go on strike because you want three cows.
JAPANESE: You have two cows. You redesign them to 1/10 the size of ordinary cows, producing 20 times the milk. You then create clever cow cartoons called Cowkimon and market them worldwide.
GERMAN: You have two cows, re-engineered so they'll live for 100 years, eat once a month and milk themselves.
BRITISH: You have two cows. Both are mad.
RUSSIAN: You have two cows. You count them and learn you have five cows. You count them again and learn you have 42. You count them again and learn you have 12. You stop counting cows and open another bottle of vodka.
SWISS: You have 5,000 cows. None belongs to you. You charge others for storing them.
HINDU: You have two cows. You worship them.
CHINESE: You have two cows and 300 people milking them. You claim full employment, high bovine productivity and arrest the newsman who questions the numbers.
They wanted to make sock eye salmon but ended up with trout?
And/ So if they start with blue fin tuna they are going to end up with mackerel?
maybe if they start with a crayfish they will get lobster? I prefer lobster anyway?
The Japanese spout trout from salmon. The Americans want to spawn salmon from trout. Allegra will grill anything.
if it tastes good I’ll eat it.
I’m going to wait to hear what the Sturgeon General has to say about it before I eat it regularly.
That was my reaction.
You won't get a colonel of truth from the Sturgeon General.
Now you're just carping.
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