Tuesday, June 28, 2011

What is the Real Difference Between Sunscreens?

It appears that there is a lot of confusion about sun screen and the Food and Drug Administration (FDA) has attempted to help the consumer by making the label more clear and truthful.

The FDA has banned exaggerated claims about sunscreens' strength and durability. Even broad-spectrum sunscreen with an SPF over 15 cannot be called "sunblock," because no lotion entirely blocks the sun's rays. Nor can sunscreen products be labeled as waterproof or sweatproof: There is no sunscreen that stays completely on the body when exposed to water. At the most, a product may be water- or sweat- resistant.

Not only do sunscreens come off the skin (particularly when exposed to water or toweled off) but their chemical components break down over time. To preserve the efficiency of sunscreens, the products should be stored in a cool, dry place and replaced every year. In addition, they should be reapplied at least every two hours or more frequently if exposed to water or rubbed off. Under the new regulations, water-resistant formulas must say on the label how long the product will protect skin before needing to be reapplied, either 40 or 80 minutes.

In addition, the FDA proposed a rule that would cap advertised SPF at "50 +", because the evidence that more expensive, higher-SPF products provide more skin protection is lacking. Many who wear high-SPF sunscreen spend more time in the sun and reapply less frequently than those whose sunscreen has a lower SPF. As a result, they end up with both sunburn and possibly long-term skin damage. In addition, many misunderstand the meaning of SPF.
Source:Scientific American: 6/27/11

Thursday, June 23, 2011

Yes, You Can Eat Insects

When the health department in Columbia, Mo., nixed a new flavor of ice cream laced with cicadas in early June from a local shop's menu, it wasn't because it's illegal to serve the winged insects to the public. "It's not really regulated," says Gerald Worley, the department's manager of environmental health, who adds, "I don't claim to be an expert on this." Nonetheless, Worley says he discouraged Sparky's Homemade Ice Cream proprietor Scott Southwick from selling the surprisingly popular flavor because Southwick "didn't really have a plan for how he would cook them," and Worley worried that the critters, which were collected from the ground, might make people sick. "We suggested that it would not be a good idea," says Worley. The first batch, in which the boiled bugs were covered with brown sugar and milk chocolate, then mixed in with an ice cream base of brown sugar and butter, had promptly sold out after the shop announced the flavor on its Facebook page.

As it turns out, cicadas have a long culinary history, and the emergence this spring of the noisy, 13-year-cyclical cricket-like insect in the Southeast and southern Midwest has brought a resurgence in cicada cuisine. Ashlee Horne of Nashville likes her cicadas sautéed in butter and garlic. Jenna Jadin of Washington, D.C., bakes them into banana bread, chocolate-chip cookies and rhubarb pie. Others like them dipped in chocolate for a sweet, crunchy snack. The inch-long bugs are widely consumed around the world, especially in East Asia, and are considered a delicacy among the Iroquois people in the U.S. Even the ancient Greek philosopher Aristotle gobbled them up: in his 4th century B.C. text Historia Animalium, he noted that the young nymphs are tastier than mature bugs, which have a harder exoskeleton, and that among adults, the egg-laden females are best. (See pictures of bug cuisine.)

So why all the fuss about eating cicadas today? "We make such a big deal out of this, but the biggest thing we have to deal with is human ignorance. They are no more germy than any other animal," says David George Gordon, author of The Eat a Bug Cookbook, who likes cicada nymphs as a pizza topping and says they have an asparagus-like flavor. Nymphs also have a chewy texture, while mature cicadas are crunchy and have more of a nutty taste, similar to that of peanuts or almonds. (See TIME's photo gallery of what the world eats.)

Entomologist Steve Murphree of Belmont University in Nashville says nymphs, which live underground for 13 years by sucking the sap of tree roots, are safe to eat raw after they emerge from the ground and shed their exoskeleton. Mature cicadas should be boiled while still alive to kill any bacteria, and already-dead cicadas should never be harvested because they could be decomposing. Also, anyone with allergies to shellfish, which belong to the same family as cicadas, should avoid the bugs altogether. (Read more about cicada ice cream.)

But bug eaters need to act fast. Once they emerge, the 13-year cicadas live for five weeks at most, according to Murphree. They can be found mostly on oak, hickory, apple and pear trees, where they lay their eggs. By the end of July, most of these so-called Brood XIX cicadas, also known as the Great Southern Brood, will have gone back underground. While the red-eyed bugs have already quieted down in Kentucky and Tennessee, the males' distinctive mating song is still piercingly loud in parts of Missouri and southern Illinois. (See the top 10 annoying sounds.)

But chances are you'll need to catch and cook them yourself, judging by the Columbia, Mo., health department's reaction to cicada ice cream. Good thing the Web is full of cicada recipes, along with tips on catching and preparing them. Meanwhile, the more timid among us can sit back and watch.
Source Time Magazine: http://www.time.com/time/nation/article/0,8599,2078830,00.html

Thursday, June 16, 2011

How Deep in the Earth Can Living Things Be Found?

Scientists already knew that single-cell organisms live in harsh, dark environments miles underground. But recently a multicellular organism, a worm, was found deep in rock nearly three-quarters of a mile underground. Nematodes are tiny worms known for being adaptable. The nematode the team found in the mine was a new species, and the scientists named it Halicephalobus mephisto.

That wasn’t the only discovery. A little more than half a mile down, the researchers found two kinds of nematodes already known to live on the surface. And more than two miles underground, the team discovered traces of nematode DNA in the water coming from cracks in the rocks.

Source: Science News 6/15/11

Tuesday, June 14, 2011

I Heard We All Have Genetic Mutations - Isn't This Bad?

The best answer to this question is from the June 13, 2011 Science News:

In a study, published online June 12 in Nature Genetics, shows that some individuals mutate faster than others. That means it may be fairly common for people to inherit a disproportionate share of mutations from one parent.

Researchers from an international collaboration known as the 1000 Genomes Project deciphered the genetic blueprints of six people from two families — a mother, father and child from each — and counted up the mutations inherited by each child. From there, the team calculated the human mutation rate.

“We all mutate,” says study coauthor Philip Awadalla, a population geneticist at the University of Montreal. “And the mutation rate can be extraordinarily variable from individual to individual.”

Combined with the results of three similar recent studies, the rate indicates that, on average, about one DNA chemical letter in every 85 million gets mutated per generation through copying mistakes made during sperm and egg production. The new rate means each child inherits somewhere in the neighborhood of 30 to 50 new mutations.

Since no one had ever directly measured the human mutation rate, the researchers weren’t sure how much variation to expect. But the scientists did anticipate that fathers would hand down more mutations than mothers, due to a well-known phenomenon called male mutation bias. The effect stems from the fact that females are born with all the eggs they will ever have, but males produce new sperm all the time. Each time cells divide to make new sperm there’s a chance mistakes will happen in the DNA-copying process.

One of the two families the researchers examined — a mother, father and child of European descent — followed the expected pattern; 92 percent of the new mutations inherited by the child came from the father. But in the other family — a mother, father and child of Yoruban descent — only 36 percent of the mutations came from the father, meaning that the mother had the higher mutation rate.

“That’s very unusual. It’s surprising,” says Adam Eyre-Walker, an evolutionary biologist at the University of Sussex in Brighton, England. That doesn’t mean that male mutation bias doesn’t exist in humans, just that some women have faster mutation rates and some men have slightly slower ones. On average, men still rack up more DNA changes per generation than women do.

The reason for the variation in mutation rate is unclear. Genetic factors may make some people more prone to getting mutations or could beef up mutation-fixing machinery in others. Environmental factors and the age of the parents at the child’s conception might also influence the mutation rate, says Peter Keightley, an evolutionary geneticist at the University of Edinburgh. More, and larger studies of this kind will be needed to determine how much people’s mutation rates vary between individuals.

Wednesday, June 8, 2011

Do Sloths Really Only Go To the Bathroom Once a Week?

Strange but true, yes, a sloth has a very slow metabolism and does only descend from the tree about once a week to defecate.

Even more interesting is that the sloth digs a hole with his/her tail at the base of the tree and the waste from the sloth serves as a nitrogen boost to the tree roots.