Sperm Travels Faster Toward Attractive Females

Females may be outwardly choosy when selecting sexual partners — accepting or shunning mates in very public ways — but males may get the last say in this battle of the sexes.

New research found that males can adjust the speed and effectiveness of their sperm by allocating more or less seminal fluid to copulations. The determining factor is whether the male finds the female attractive.

The study, conducted on red junglefowl, a director ancestor of chickens, adds to the growing body of evidence that males throughout many promiscuous species in the animal kingdom, including humans, can mate with many females, but chances of fertilization are greater when the female is deemed to be attractive.

Desirable female red junglefowl are easy to identify.

“Female attractiveness is determined by the expression of a sexual ornament — the comb — which is phenotypically and genetically correlated to the number and mass of eggs females lay,” according to study co-authors Charlie Cornwallis of the University of Oxford and the Royal Veterinary College’s Emily O’Connor.

For the study, published in the current Proceedings of the Royal Society B, the researchers collected natural ejaculates from dominate and subordinate red junglefowl males housed at the University of Stockholm. The males had either just mated with attractive or unattractive females.

Swine flu: Your questions answered

1. Hasn’t swine flu been around for a while?

Yes. Swine flu was first identified in 1930 when researchers isolated the virus in a pig. In 1976, more than 200 soldiers at Fort Dix, New Jersey, got swine flu. From 1976 until 2005, the U.S. Centers for Disease Control and Prevention received approximately one report every year or two of humans with swine flu. From December 2005 until January 2009, there were 12 cases of swine flu reported.

2. The folks who have it now, did they get it from pigs or people?

It appears that no one in the United States with swine flu had any contact with pigs. Dr. Richard Besser, the acting director of the CDC, said in a news conference Friday that among the first seven cases, no one had contact with pigs. In another press conference Monday, he added that investigators have looked to see whether any of the infected people had contact with pigs, and “we’re not finding that linkage here.”

3. Swine flu is transmitted from animals to humans. Does that happen a lot?

Yes. More than 200 “zoonotic diseases” are transmitted from animals to humans, including illnesses caused by bacteria, viruses and parasites. Rabies and variant Creutzfeldt-Jakob disease (better known as “mad cow disease”) are two well-known examples.

4. Should I cancel my trip to Mexico?

Yes, you should, unless it’s essential. That’s the advice from a recent CDC travel warning. Watch Elizabeth Cohen answer your questions »

5. Should I be freaking out?

A new virus spreading quickly around the world. Young, healthy people struck dead in Mexico. Should we all be panicking?

“Absolutely not,” said Dr. William Schaffner, chairman of the department of preventive medicine at Vanderbilt University School of Medicine. Swine flu, he said, “is not spreading all that rapidly. Take the St. Francis School in New York. There’s been very little transmission from the schoolchildren to family members, and it certainly hasn’t spread throughout Queens.” iReport.com: Share your thoughts, concerns about swine flu

But, Schaffner added, this doesn’t mean we shouldn’t pay attention to swine flu. “We should be alert, keep up with the information coming out daily, and take control by being attentive to your hygiene. Wash your hands very, very frequently and avoid people who are coughing and sneezing.”

6. How close do you have to be to a sick person to get swine flu?

“You can acquire this infection if you’re within the ‘breathing zone’ of a sick person, which is about three to six feet,” Schaffner said. “And we usually mean being this close to someone in a confined space. We’re not talking about fleeting contact. We’re not talking about walking past someone in the street. You need sustained contact.” If you think you might have sustained contact with someone who’s ill, read this guidance from the CDC’s Web site.

7. Yikes! Every day I’m that close to countless people — at work, on the bus, at church, in a movie theater. Could I get swine flu from them?

Yes.

“If you’re standing next to someone on a bus, or sitting next to someone or in front of someone in a theater, you could acquire the infection in that fashion,” Schaffner said. That’s why people with the symptoms of any kind of flu — fever, diarrhea, body aches, vomiting, etc. — are urged to stay home and away from groups of people.

8. Wasn’t there a vaccine at one time? Is there one now?

Yes, a swine flu vaccine was given to 45 million people in 1976. There is no vaccine now, although researchers are working on one.

The 1976 vaccine wouldn’t be helpful anyway, according to Dr. Anthony Fauci, director of the National Institute for Allergy & Infectious Diseases.

“That was a completely different virus than the virus we are dealing with right now, completely different in the sense that the genes are different, and it doesn’t have any relationship,” said Fauci. “The designation of each one was called the swine flu, but from a viral standpoint and spreading it is quite, quite different.”

Here are two scientific articles about the swine flu outbreak and vaccination program in 1976:

•Reflections on the 1976 Swine Flu Vaccination Program

•Swine Influenza A Outbreak, Fort Dix, New Jersey, 1976

9. Many young, healthy people have become sick in the United States. Many of the dead in Mexico have been young and healthy. What’s going on? Usually we think of flu as affecting the very young and the very old.

This sometimes happens with new viruses. For example, in 1918 when a new flu virus emerged, many of those stricken were young and healthy. One theory is that young people, who have strong immune systems, mount a particularly vigorous response to new viruses. But there’s a potential side effect to the response: the body releases dangerous levels of signaling proteins, called cytokines, which can damage the lungs. Scientists believe these “cytokine storms” can be fatal.

Here is a scientific article about the proposed mechanism of cytokine storms.

10. Why are large numbers of people dying in Mexico, but not in other countries?

This is the big mystery doctors are trying to solve right now. Many infectious disease experts say it’s most likely a matter of numbers: with more illnesses in Mexico, there are also more deaths. Other explanations: that in Mexico people have, in addition to swine flu, other viruses that make for a more deadly combination than swine flu alone. It’s also possible that the virus infecting the rest of the world is a weaker version than the one in Mexico. Among the swine flu mysteries: Why only deaths in Mexico?

11. Could this new swine flu virus have been manufactured by bioterrorists?

That’s the theory on some conspiracy theorists’ Web sites. But experts don’t believe it.

“If you were a bioterrorist you’d want to create something that’s a lot more deadly than this,” said Dr. Gerald Evans, an associate professor of microbiology at Queen’s University in Canada. “The problem with influenza is that the second you put it into people, it replicates and mutates very quickly. Even if you created the perfect bioweapon, within a few generations of transmissions, it wouldn’t do what you planned for it to do.”

12. I get a flu shot every fall. Will that help protect me against swine flu?

“The short answer is that the CDC says it’s very unlikely,” Schaffner said. But he said it might be possible. “I think it’s a bit of an open question whether repeated flu shots over years would provide a measure of protection.”

13. Can the swine flu virus live on inanimate objects? If someone with swine flu touches a doorknob, then I touch it, could I get swine flu?

Flu viruses can live on inanimate surfaces. So theoretically, you could get swine flu from touching a doorknob that was just touched by an infected person. However, that’s pretty unlikely, according to Dr. Arthur Reingold, head of epidemiology in the School of Public Health at the University of California, Berkeley.

“I personally would not have a major fear of environmental contamination,” he said. “Virtually all influenza is transmitted from sneezing and coughing.”

Schaffner agrees, adding that flu viruses don’t survive in large numbers on surfaces. “A doorknob isn’t a warm, nurishing environment for a virus,” he said.

15. What should I do if I develop symptoms of swine flu?

Call your doctor — don’t just drive on over, Schaffner advised. “Follow the instructions of your doctor. He might not want you in the waiting room spreading germs to others,” he said

Studies of ‘good’ fat could help with weight loss

Fight fat with fat? The newest obesity theory suggests we may one day be able to do just that. Just like good and bad cholesterol, there apparently are good and bad types of body fat. Scientists until recently believed this good fat, which spurs the body to burn calories to generate body heat, played an important role in keeping infants warm but by adulthood was mostly gone or inactive. Now three studies � from researchers in Boston, Finland and the Netherlands � show that some good fat remains in adults, affecting metabolism and potentially offering a target to help people shed pounds. Dr. Francesco Celi, an endocrinology and metabolism researcher at the National Institute of Diabetes and Digestive and Kidney Diseases, said the studies show this fat burns large amounts of energy. “So it could be used as a target” for a pill that would somehow rev up the fat, he said. Dr. Louis Aronne, former president of the Obesity Society and a weight control expert at Weill Cornell Medical Center in New York, said the findings are the most conclusive evidence so far of the role of such fat in regulating body temperature and weight. “I don’t want to use the word ‘exercise-in-a-pill,’ but it’s doing something (that’s) getting rid of calories,” he said, adding that any obesity treatment developed around the fat could be a potential treatment for diabetes as well. The studies were published in Thursday’s New England Journal of Medicine. The good fat is actually brownish, while the more predominant bad fat is white or yellow. Brown fat is stored mostly around the neck and under the collarbone. White fat tends to concentrate around the waistline, where it stores excess energy and releases chemicals that control metabolism and the use of insulin. All three research groups documented the presence and activity of the brown fat by examining tissue samples from some patients and using high-tech imaging that indicated how much sugar, and therefore calories, the fat burned. One group from Joslin Diabetes Center, Harvard Medical School and three hospitals in Boston looked at scans done on nearly 2,000 patients to diagnose various health problems. The other two groups scanned small numbers of patients, first at room temperature and then after a couple hours in mild cold, about 60 degrees. Here’s what the scientists learned about brown fat: • Lean people had far more than overweight and obese people, especially among older folks. • It burns far more calories and generates more body heat when people are in a cooler environment. • Women were more likely to have it than men, and their deposits were larger and more active. Finding a successful treatment for obesity would be a Holy Grail for scientists. Most obese and overweight people are unable to shed pounds and keep them off with dieting and exercise. And despite plenty of effort, pharmaceutical companies have been unable to develop a medicine that helps people safely lose and keep off a significant amount of weight. Any drug that could do that would be a guaranteed blockbuster. Aronne said the findings likely would renew interest in the area of brown fat among drugmakers; at least one briefly studied a treatment in lab animals several years ago. So how could researchers use these basic findings about good fat to eventually come up with a weight-loss medication? One possibility would be a pill to stimulate a specific protein to release more energy from the fat cells in the form of heat rather than storing it for future energy needs, Aronne and Celi said. Finding a way to increase the amount of brown fat in a person would be another strategy. Researchers at Dana-Farber Cancer Institute in Boston have been injecting certain genes into mice to try to produce brown fat cells instead of white ones. Celi said researchers also could try to make a pill that stimulates nerve endings inside brown fat to make it burn more calories. Or overweight people could simply try turning down the thermostat to see if it makes them burn more energy and lose weight � a strategy that Celi and researchers are testing in a small study that could produce results by the end of the year. On the Net: New England Journal: http://www.nejm.org