Rapid Evolution Gives Sperm the Advantage

By Jeanna Bryner, Senior Writer

Semen, the stuff that ferries sperm, contains proteins that evolve swiftly to help males compete for paternity, suggests new research on fruit flies.

The high-stakes competition between male fruit flies vying for a top mating spot with females could be driving the fast-evolving proteins, according to the study published in the July 29 issue of the journal PLoS Biology.

"They change with the quickness we would expect for the immune system, which has to respond fast to new pathogens," said researcher Michael MacCoss of University of Washington's Department of Genome Sciences in Seattle.

Though the study results are based on fruit flies, they do have implications for humans and other animals that also reproduce sexually.

"We think that if we can understand what are the pressures that are driving the rapid changes of these proteins in a system that's easier to study, like flies, we can get a handle on what may be causing the changes in humans," said lead study scientist Geoffrey Findlay, also of UW.

Findlay's team compared DNA sequences of semen proteins between closely related species of fruit flies, finding that the same proteins in different species had different arrangements. They also identified semen proteins that were unique to certain species.

They discovered more than 80 previously unknown proteins that play a role in reproduction, confirming 70 others that had been predicted to be involved, that get transferred to female fruit flies via semen.

Semen advantage

Female fruit flies mate with several males during their lifetimes, storing the sperm at different times in specialized organs.

"If you've got sperm from different males, all competing for fertilization success, than anything a male can do to increase the chances of his sperm winning and decrease the chances of other males' sperm winning is going to be advantageous," Findlay told LiveScience. "It could be that these proteins have evolved to increase that fitness."

Semen proteins could, for instance, cue the female to lay eggs immediately upon getting the semen goods, and could make females less likely to mate again with another male, the researchers explain. Perhaps certain proteins "disarm" the seminal proteins transferred to females by other males, they say.

Staying on top

There's a little twist, however. If a mutation imparts super-hero qualities to a male's sperm, over time that mutation would become a part of every male fruit fly's reproductive repertoire.

The researchers found that to counter this plateau of fitness, male fruit flies may have acquired duplicates of proteins.

"One copy can be held constant and in the other copy the mutation can play around with that copy and if it happens to hit on a beneficial mutation in the second copy, then that copy can diverge and maybe provide a new advantage," Findlay said.

They found 15 such duplications in the male reproductive genes. He added, "We think this is evidence of the continuing arms race, or sort of struggle, for reproductive success.

Original here

U.S. food portions: Monuments of decadence?

By Jasmin Melvin

WASHINGTON (Reuters) - After having dinner at Clyde's in Washington's trendy Chinatown, a young boy sluggishly gets up to follow his family to the exit. His waitress jokes, "You're stuffed, huh?"

The boy lets out a grunt, saying, "Yeah, I'm full. I feel like I'm going to burst," as he ambles to the door.

Such is the response of many customers who venture into the popular restaurant. One waitress said, "It depends on the dish, but I've never gotten a complaint that it's too little."

But with soaring food prices sparking protests in many countries and more than 800 million people going hungry every day, U.S. food portions are under scrutiny. A lightening of the American plate could ease pressure on worldwide demand, but not everyone is hopeful change will be coming any time soon.

With a bombardment of food ads, many aimed at children, Americans are tempted with an array of food choices. One fast-food chain calls its massive burger a "monument to decadence" while the Wendy's chain calls its "Baconator" a "mountain of mouth-watering taste."

Portion sizes in the United States not only exceed those in less-developed countries, but also in the developed world. In fact, Americans have the highest per capita daily consumption in the world, eating 3,770 calories a day, more than a Canadian at 3,590 calories or an Indian at 2,440, according to data from the U.N. Food and Agricultural Organization.

"We've looked at large portion sizes almost entirely in terms of whether it's healthy for us, and now we have to consider is that sort of a demand going to be sustainable," said Paul Roberts, author of "The End of Food."

Roberts believes smaller portions would help. "It would probably be a way to take pressure off of grain markets if we somehow convinced people to take smaller portion sizes."

In the United States, food prices are expected to rise 4.5 percent to 5.5 percent this year, which would be the highest increase since 1990.

FEWER GROCERIES

Americans are putting more thought into food buying. High food prices coupled with a slowing economy have led 71 percent of Americans to eat out less and 48 percent are buying fewer groceries, according to the Food Marketing Institute.

Raj Patel, author of "Stuffed and Starved: The Hidden Battle for the World Food System," said consumer buying habits are changing, including in the United States.

"But, it's unusual to see it in the United States, where I've seen reports of low income American families doing what low income families in the third world do, which is skipping meals, particularly women skipping meals so their kids can eat," Patel said.

He said there is also a boom in Spam and other low quality meats. "There's certainly a sort of downshift in the quality and sometimes, for the poorest Americans, the quantity of food they're able to afford."

Restaurants are also being hit hard by the rise in food prices.

Between February 2006 and February 2008, wholesale food prices have soared 15.5 percent, according to Michael Donohue, a spokesman for the National Restaurant Association. But as of January, menu prices only increased by 3.9 percent, compared with the 5.8 percent increase in grocery store prices.

Donohue said some 133 million Americans eat out every day. "The typical adult eats at a restaurant nearly six times a week, and more than half say eating out is an essential part of their lifestyle," he said.

But restaurants are not making big reductions in portions, making only small moves like not automatically refilling bread baskets or introducing calorie counter options.

"I've seen some anecdotal reports in the press about restaurants saying they're making the portions a little bit smaller in order to save money, but I haven't seen that as a general trend in going into restaurants," said Margo Wootan, director of nutrition policy at the Center for Science in the Public Interest.

Wootan said large portion sizes are unlikely to fade away despite increasing food costs since the actual farm value of food is low for restaurants compared to other costs, such as labor, advertising and transportation.

"So if you pay a dollar for an order of French fries only about 20 cents goes for the potatoes, the oil and the salt," she said. "When a restaurant sells a large fry instead of a small fry, the cost of the potatoes themselves adds only a little bit of cost and all their other costs of doing business stay the same. So companies make a lot more profit off of big portion sizes."

President George W. Bush caused a stir earlier this year when he blamed India's growing wealth and demands for better food for raising food prices. But many worldwide pointed the finger back at Americans' tummies.

But author Patel said ironically it is the poor in America that are driving consumption.

"Yes, portion sizes are large in the U.S., but people who tend not to have choice about portion sizes are people who are on lower incomes who buy prepackaged food, which comes in those fixed portion sizes," Patel said. "Blaming the consumer for what is available on the market isn't a satisfactory explanation for why there's a food crisis."

Patel points the finger at large-scale agribusiness, whom he believes is profiting from the crisis.

To be sure, tight worldwide food supplies also weigh.

"U.S. food consumption hasn't changed in 10 years," said Ephraim Leibtag, a U.S. Department of Agriculture economist. He contends the problem is really due to rising worldwide consumption while supplies are not keeping pace.

But Leibtag did agree that U.S. food consumption is high.

"Potentially, and this is up for debate, a benefit of higher prices is lower consumption, and, in this country, that actually would not be a bad thing overall."

(Editing by Russell Blinch and Philip Barbara)

Original here

Arctic Ice Shelf Sheds Biggest Chunk Since 2005, Globe Says

By Alex Morales

July 29 (Bloomberg) -- An ice shelf in northern Canada has shed its biggest chunk since 2005, a sign global warming is re- shaping the Arctic coastline, the Globe and Mail reported.

The 4-square-kilometer (1.5-square-mile) piece broke off last week, the newspaper said, citing Sami Soja, a surveyor working for Parks Canada who witnessed part of the event. It's the biggest piece shed since the entire Ayles shelf, one of Canada's six major ice shelves, broke off in 2005, creating a 66- square-kilometer frozen island, the newspaper said.

Over the past century, 9,000 square kilometers of ice attached to the Arctic coastline have shrunk to less than 1,000 square kilometers, the Globe and Mail said. The rest of the Ward Hunt shelf may continue to weaken over time and then suddenly break, the newspaper said, citing Derek Mueller, a scientist who has monitored ice in the area of the latest break.

To contact the reporter on this story: Alex Morales in London at amorales2@bloomberg.net.

Original here