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Drosophila melanogaster Redux

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Drosophila melanogaster Redux

Postby M. Henri Day » Fri Jun 03, 2005 10:37 am

Say what one will about fruit flies, but they certainly give one pause....

Henri

June 3, 2005

For Fruit Flies, Gene Shift Tilts Sex Orientation

By ELISABETH ROSENTHAL,
International Herald Tribune


When the genetically altered fruit fly was released into the observation chamber, it did what these breeders par excellence tend to do. It pursued a waiting virgin female. It gently tapped the girl with its leg, played her a song (using wings as instruments) and, only then, dared to lick her - all part of standard fruit fly seduction.

The observing scientist looked with disbelief at the show, for the suitor in this case was not a male, but a female that researchers had artificially endowed with a single male-type gene.

That one gene, the researchers are announcing today in the journal Cell, is apparently by itself enough to create patterns of sexual behavior - a kind of master sexual gene that normally exists in two distinct male and female variants.

In a series of experiments, the researchers found that females given the male variant of the gene acted exactly like males in courtship, madly pursuing other females. Males that were artificially given the female version of the gene became more passive and turned their sexual attention to other males.

"We have shown that a single gene in the fruit fly is sufficient to determine all aspects of the flies' sexual orientation and behavior," said the paper's lead author, Dr. Barry Dickson, senior scientist at the Institute of Molecular Biotechnology at the Austrian Academy of Sciences in Vienna. "It's very surprising.

"What it tells us is that instinctive behaviors can be specified by genetic programs, just like the morphologic development of an organ or a nose."

The results are certain to prove influential in debates about whether genes or environment determine who we are, how we act and, especially, our sexual orientation, although it is not clear now if there is a similar master sexual gene for humans.

Still, experts said they were both awed and shocked by the findings. "The results are so clean and compelling, the whole field of the genetic roots of behavior is moved forward tremendously by this work," said Dr. Michael Weiss, chairman of the department of biochemistry at Case Western Reserve University. "Hopefully this will take the discussion about sexual preferences out of the realm of morality and put it in the realm of science."

He added: "I never chose to be heterosexual; it just happened. But humans are complicated. With the flies we can see in a simple and elegant way how a gene can influence and determine behavior."

The finding supports scientific evidence accumulating over the past decade that sexual orientation may be innately programmed into the brains of men and women. Equally intriguing, the researchers say, is the possibility that a number of behaviors - hitting back when feeling threatened, fleeing when scared or laughing when amused - may also be programmed into human brains, a product of genetic heritage.

"This is a first - a superb demonstration that a single gene can serve as a switch for complex behaviors," said Dr. Gero Miesenboeck, a professor of cell biology at Yale.

Dr. Dickson, the lead author, said he ran into the laboratory when an assistant called him on a Sunday night with the results. "This really makes you think about how much of our behavior, perhaps especially sexual behaviors, has a strong genetic component," he said.

All the researchers cautioned that any of these wired behaviors set by master genes will probably be modified by experience. Though male fruit flies are programmed to pursue females, Dr. Dickson said, those that are frequently rejected over time become less aggressive in their mating behavior.

When a normal male fruit fly is introduced to a virgin female, they almost immediately begin foreplay and then copulate for 20 minutes. In fact, Dr. Dickson and his co-author, Dr. Ebru Demir of the Institute of Molecular Biotechnology, specifically chose to look for the genetic basis of fly sexual behavior precisely because it seemed so strong and instinctive and, therefore, predictable.

Scientists have known for several years that the master sexual gene, known as fru, was central to mating, coordinating a network of neurons that were involved in the male fly's courtship ritual. Last year, Dr. Bruce Baker of Stanford University discovered that the mating circuit controlled by the gene involved 60 nerve cells and that if any of these were damaged or destroyed by the scientists, the animal could not mate properly. Both male and female flies have the same genetic material as well as the neural circuitry required for the mating ritual, but different parts of the genes are turned on in the two sexes. But no one dreamed that simply activating the normally dormant male portion of the gene in a female fly could cause a genetic female to display the whole elaborate panoply of male fruit fly foreplay.

Copyright 2005 The New York Times Company
曾记否,到中流击水,浪遏飞舟?
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Postby KatyBr » Fri Jun 03, 2005 11:20 am

Oh please, Henri, this does go beyond the pale. What has this to do with language and words anymore than any of your (lightly) veiled political agenda articles......

I find it offensive, no doubt BD and Luis will find it acceptable, but hey, can we keep this a more family forum?
this is in poor taste.
Katy
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Postby anders » Fri Jun 03, 2005 12:01 pm

My favourite fruit flies:

Biology teacher: Today we'll discuss an animal, very important to genetics. (writes on the blackboard (yes, it's an old story)): Friut fly.

Assorted laughter in class. Realizing the mistake, teacher rubs it out and writes, slightly irritated: Frut fly.

Louder reaction. Forceful deleting, and then teacher writes quickly and decidedly: Drosophila melanogaster.
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Postby M. Henri Day » Fri Jun 03, 2005 12:19 pm

KatyBr wrote: ... but hey, can we keep this a more family forum?
this is in poor taste.


Presumably the reason we have a forum entitled «Res Diversæ» is to encourage discussion on matters that are not explicitly linguistic. I don't find a discussion on genes that regulate the expression of sexuality, whether in humans, fruit flies, or Tasmanian devils, in «poor taste», and I should rather be pleased than dismayed were members of my family to participate. In any event, so long as the forum exists, I intend to avail myself of it....

Henri
曾记否,到中流击水,浪遏飞舟?
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Postby M. Henri Day » Fri Jun 03, 2005 12:28 pm

Here, another article which touches on gender without, to my mind, violating the canons of taste or being unsuited for family reading....

Henri

washingtonpost.com
Fossil's Bone Tissue Points to Sex of T. Rex


By Guy Gugliotta
Washington Post Staff Writer
Friday, June 3, 2005; A03


How do you tell a girl T. rex from a boy T. rex ?

Not very easily, but a team of paleontologists has identified a young lady from Montana's Hell Creek Formation because her fossilized remains contain a special bone tissue that forms in female birds when they are getting ready to lay eggs.

The research, reported today in the journal Science, marks the first time that scientists have ever sexed a Tyrannosaurus rex , and the technique could work with other species -- as long as the skeleton is that of a female during the egg-laying cycle.

"But it's a pretty rare event" to find such a fossil, cautioned North Carolina State University's Mary H. Schweitzer, the leader of the research team. "Not too many of them die in the middle of the laying season. They die when they stop producing eggs."

Schweitzer suggested that the research may be just as valuable as evidence in the still somewhat controversial debate over the link between modern birds and dinosaurs, which went extinct 65 million years ago. The tissue in the Hell Creek specimen closely resembles similar tissue in ratite flightless birds such as emus and ostriches.

The Hell Creek female, discovered beneath 1,000 cubic yards of sandstone in northeast Montana, is rapidly becoming one of the most famous dinosaur fossils ever found. In March, the Schweitzer team announced that a thighbone, or femur, from the specimen, a young adult about 18 years old when it died, contained soft tissue that had survived for 70 million years.

"It's an outstanding fossil," said team member John Horner, curator of paleontology at Montana State University's Museum of the Rockies, where the remains are being studied. "And the likelihood of finding another dinosaur with this kind of material is really low."

Schweitzer said the discovery reported today came during the team's examination of the same cross section of femur that eventually produced the soft tissue. Horner said a thin, spongy-looking layer of bone lining the femur's inner cavity was visible to the naked eye and had clearly been permeated with blood vessels when the creature was alive.

The team reasoned that the tissue was "medullary bone" similar to that formed by female birds today when ovulation begins the egg-laying cycle. Schweitzer said the bone is an "ephemeral feature," a reservoir of calcium deposited in the bone cavity and drawn upon to build eggshells. As the T. rex laid eggs, the medullary bone depleted and finally disappeared, as it does with modern birds, at the end of the cycle.

But while "the tissue is a good marker for [determining the sex of] ovulating females," Schweitzer said, its absence indicates nothing -- the specimen free of medullary tissue could be male or a non-ovulating female.

What the new skeleton may offer, however, is a benchmark for further T. rex research: "Now that we have an individual that we know is female, we can look for other characteristics in the skeleton that are different," Horner said.

Unfortunately, dinosaurs, including T. rex , do not show much evidence of "sexual dimorphism" -- physical differences between males and females. Many dinosaurs are strange-looking, such as stegosaurus or triceratops, but all the known fossils of these species are similar.

"If there was a difference, we would have already seen it," said Horner, a leading advocate of the theory that dinosaurs were odd-looking not because they wanted to show off for potential mates but simply so they could -- in an extremely hostile world -- easily identify other members of their own species.

"People have been wondering about sexing dinosaurs since the 1920s, and it's amazing how little we know," added Hans-Dieter Sues, associate director of research and collections at the National Museum of Natural History. "It's not like humans -- where you can tell by the shape of the pelvis. With dinosaurs, you don't get anything like that."

Also, Sues said, "the sample for most species is much too small." For most dinosaurs "you're lucky if you can get even a partial skeleton," he said. "And you can't find out very much from that."

The world's largest T. rex fossil, in Chicago's Field Museum, is nicknamed Sue after its discoverer, but its chances of being sexed by the medullary bone method may be limited because scientists reckon the dinosaur was 28 years old and suspect it may have suffered from arthritis and died at least in part because of old age.

Horner said researchers could try the medullary bone technique on other species, especially smaller raptors and the other predatory, meat-eating "therapods" that appear to be more closely akin to modern birds than other dinosaurs.

"Therapods also have big, hollow marrow cavities like what we saw in T. rex ," Horner said. But while the leg bones in plant-eating "sauropods" are thicker with smaller cavities, they may also have medullary bone: "We find a lot of sauropods in nesting areas," Horner said. "Those are the first ones I'd look at."

© 2005 The Washington Post Company
曾记否,到中流击水,浪遏飞舟?
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Postby Flaminius » Fri Jun 03, 2005 1:15 pm

One wonders how many newspapers Henri reads everyday and manage to keep electroistic (internet or Web but I am rather loathe to adj. nouns :lol: ) records of the articles that he "finds of interest." While I am beginning to suspect Henri is a collective pen-name of a bunch of newspaper promoters, I certainly appreciate his eye-straining mortification by staring at gleaming PC screen for a long time.

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Postby KatyBr » Fri Jun 03, 2005 1:18 pm

M. Henri Day wrote:
KatyBr wrote: ... but hey, can we keep this a more family forum?
this is in poor taste.


Presumably the reason we have a forum entitled «Res Diversæ» is to encourage discussion on matters that are not explicitly linguistic. I don't find a discussion on genes that regulate the expression of sexuality, whether in humans, fruit flies, or Tasmanian devils, in «poor taste», and I should rather be pleased than dismayed were members of my family to participate. In any event, so long as the forum exists, I intend to avail myself of it....

Henri

It was less a discussion of genes than
The discriptions of the mating of the fruit flies which is an obvious male self-titillation exercise,
(THIS REMINDS ME OF THE COYLY ENCODED <<SEKS>> IN THE SUBJECT LINES FROM MASTER PORN SPAMMERS)the much more general discriptions of Tasmanian Devil copulations was oc, your testing the waters, so to speak. I know I'm fighting the losing battle here, but I say, Please, stop it here. I do have the right to object, and your "oh now, you poor dear, don't trouble your head" admonitions (couched in your own way oc) smacks of the worst of the old male-domination chauvinism.

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Postby Stargzer » Fri Jun 03, 2005 9:50 pm

Looks like we'll have to put a KatyWarning at the beginning of any post that threatens the Midwestern Mores.

I saw that article today on another site, LiveScience.com and found it interesting. There was also a Top Ten list of the most useless vestigial organs or behaviors.

Number One was the Human Appendix.

DANGER WILL ROBINSON! KATYWARNING!

Number Two was Male Breast Tissue and Nipples

Number Three was Fake Sex in Virgin Whiptail Lizards (Vestigial Behavior)
Only females exist in several species of the lizards of the genus Cnemidophorus, which might seem like a problem when it comes time to propagate the species. The females don’t need the males though, they reproduce by parthenogenesis, a form of reproduction in which an unfertilized egg develops into a new individual. So basically, the females don’t need the males; they just produce clones of themselves as a form of reproduction. Despite the fact that it is unnecessary and futile to attempt copulation with each other, the lizards still like to try, and occasionally one of the females will start to “act like a male” by attempting to copulate with another female. The lizards evolved from a sexual species and the behavior to copulate like a male -- to engage in fake sex -- is a vestigial behavior; that is, a behavior present in a species, but is expressed in an imperfect form, which in this case, is useless.


Number Four was The Sexual Organs of Dandelions

Number Five was Wisdom Teeth in Humans

Number Seven was The Human Tailbone (Coccyx)

Number Eight was Erector Pili and Body Hair.


Partheogenesis reminds me of a science fiction novella I read several years ago in which a woman woke up in a future world in which there were no men, then woke back up in the present and resolved to do something about the situation. Of course it backfired. (Origin of Parthenogenesis)
Regards//Larry

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Postby KatyBr » Fri Jun 03, 2005 11:05 pm

I KNEW I WAS FIGHTING A LOSING BATTLE HERE, LARRY I'VE NEVER OBJECTED TO YOUR POTTY HUMOR OR LOCKER ROOM POSTINGS, mostly because I knew you good ol boys have to raunch out everyso often to prove to yourself they are still there.
But you are crossing the line. And I'm not from the Midwest, I live now in the NorthEast, and I'm From the West Coast, talk about ad hominim, Larry shame on you.

Katy
This will mark the long slow slide into just another raunchy mg, so be it.
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Postby tcward » Fri Jun 03, 2005 11:33 pm

Well, I guess I'm just a "good ol' boy", too, then (speaking of which, smells like an ad hominem to me), because I don't see anything raunchy in this thread.

And I was taught that Michigan is a Midwest State. Every link I just looked up also corroborates this. North Carolina, on the other hand, is one of those states that people sometimes group with the Mid-Atlantic States, but I don't really see how they think that.

-Tim
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Postby M. Henri Day » Sat Jun 04, 2005 3:04 pm

KatyBr wrote: ...
It was less a discussion of genes than
The discriptions of the mating of the fruit flies which is an obvious male self-titillation exercise,
(THIS REMINDS ME OF THE COYLY ENCODED <<SEKS>> IN THE SUBJECT LINES FROM MASTER PORN SPAMMERS)the much more general discriptions of Tasmanian Devil copulations was oc, your testing the waters, so to speak ...


Katy, you make me feel old ! I didn't become the least titillated when reading the description of the mating rites of male Drosophila, nor did my brittle (?) hormones respond with a rush when I posted the piece to the forum. Moreover, I fear I should be as unlikely a master in the role of porn spammer as I am as in that of male chauvinist pig - my talents, to the degree that such exist, lie elsewhere. But on the other hand, my wonder at the world about me - and my desire to share it with others - has, like my titillation threshold, merely increased with time....

Henri
曾记否,到中流击水,浪遏飞舟?
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Postby Spiff » Mon Jun 06, 2005 8:20 am

Interesting discussion this. So, what are the Mid-Atlantic states exactly, Tim? 8)
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Postby anders » Mon Jun 06, 2005 12:18 pm

Flaminius wrote:While I am beginning to suspect Henri is a collective pen-name of a bunch of newspaper promoters[...]
Flam

At least, I can assure you that there was in 1975 a doctoral thesis by a certain M. Henri Day, "Máo Zédōng 1917-1927 Documents". The author translates and comments several documents, making, for example, good use of the Dai Kanwa Jiten! That's some awesome 400 pages.
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Geographical Trivia

Postby Stargzer » Mon Jun 06, 2005 2:27 pm

Spiff wrote:Interesting discussion this. So, what are the Mid-Atlantic states exactly, Tim? 8)


Here's Wikipedia's definition of the Mid-Atlantic States.

The Mid-Atlantic region of the United States of America, located in the northeastern section of the country, includes the following states and district:

Delaware
Maryland
New Jersey
New York
Pennsylvania
Washington, D.C.
Virginia

These areas provided the young United States with heavy industry and served as the "melting pot" of new immigrants from Europe. Cities grew along major shipping routes and waterways. Such flourishing cities included New York City on the Hudson River, Philadelphia on the Delaware River, and Baltimore on Chesapeake Bay.

As defined by the US Census Bureau, the Mid-Atlantic is a division of the U.S. Northeast region, and comprises New Jersey, New York, and Pennsylvania. Delaware, Maryland, and Washington, D.C. are treated as being in the U.S. South region.


D.C is the District of Columbia, the capital city of the US. It it not, and never has been, a state, which has miffed many of its residents over the years.

Since they are both below the Mason-Dixon line, Maryland and Delaware qualify as Southern states if one follows that line of reasoning. (I'll bet most Southerners don't know that the Mason-Dixon line is the southern border of Pennsylvania.)
Regards//Larry

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Postby uncronopio » Mon Jun 06, 2005 6:36 pm

I found the post interesting but, well, I am a geneticist... If any of you are interested in this type of stories I recommend the book Genome: the autobiography of a species, by Matt Ridley. It is really fascinating.
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