Genetics May Explain Why Autism Is More Common in Boys

When it comes to developmental disorders of the brain, men and women are not created equal.

Decades of research have shown that males are at far greater risk for neurodevelopmental disorders such as autism spectrum disorder (ASD) than females. Boys, on average, are five times more likely to have autism than girls . What causes this disparity has largely remained unknown.

Now scientists have uncovered compelling genetic evidence to explain why the biological scales aren’t balanced.

According to a team of geneticists in the U.S. and Switzerland, it all boils down to what’s called the “female protective model.” This suggests that girls have a higher tolerance for harmful genetic mutations and therefore require a larger number of them than boys to reach the diagnostic threshold of a developmental disorder. With identical genetic mutations, then, a boy could show symptoms of ASD while a girl could show none.

But because the female mutation threshold is higher, when girls are diagnosed with ASD, they tend to fall on the more severe end of the spectrum.

Researchers believe the same dynamic could explain why more boys are diagnosed with ADHD, intellectual disabilities and schizophrenia. The findings were published Thursday in the American Journal of Human Genetics.

Geneticists analyzed DNA samples from 16,000 boys and girls with neurodevelopmental disorders. They found that, on average, females diagnosed with ASD had 1.3 to 3 times more harmful genetic alterations than males diagnosed with the disorder.

The findings suggest that as the male brain develops, smaller and more subtle genetic changes can trigger autism spectrum disorders. Female brains require a greater number or severity of mutations before showing symptoms, so their symptoms tend to be worse.

“There’s no application in terms of treatment,” said study author Sébastien Jacquemont of University Hospital of Lausanne in Switzerland, but “it does help understand the inheritance dynamics in families.”

Jacquemont also studied some 800 families in which a family member was affected by ASD. He found that children were more likely to inherit gene mutations linked to autism from their mothers. Jacquemont says this may be because a male with a severe form of autism may have more trouble forming relationships and be less likely to have children. In contrast, the same genetic glitches in a female could go unnoticed, Jacquemont says, so that woman may be more likely to start a family and unknowingly pass the genes to her offspring.

The study doesn’t answer the most profound question surrounding the genetics of neurodevelopmental disorders: “What causes these disorders?” It’s still unclear which particular genetic glitches are responsible for different manifestations of developmental disorders. Or if genetic alterations are even passed down from parents, rather than simply appearing in children as they develop. Jacquemont is hoping to form larger cohorts to study which mutations put children at risk for ASD and other neurodevelopmental disorders.

Still, some researchers aren’t convinced that genetics are even the way to answer questions about neurodevelopmental disease. Irva Hertz-Picciotto, an epidemiologist at the University of California-Davis, told USA Today,

“Boys are swimming in measurably more testosterone than girls are. Some evidence suggests that social behaviors are in part determined by such early life exposures to sex steroids.”

Still, advances in the genetics of neruodevelopmental disorders could help families gain insight into whether their children are likely to inherit genetic markers associated with disorders like autism.

Image credit:  Zurijeta/Shutterstock

View the original article here

How Does Crop Biotechnology Help Food Security?

In the U.S. food is taken for granted. There are well-stocked supermarkets and no shortage of cookbooks and eateries to indulge appetites. This bountiful supply allows Americans to focus more on the aesthetics of food and, to an increasing degree, where and how it is produced.

For the millions around the globe who do not live in an affluent society, the main concern about food is more basic: Getting enough of it on a consistent basis. For many in Africa and Asia, this entails growing cash crops and staple foods.

As the Gates Foundation points out, agricultural enhancement in the developing world is also the key to a better life:

When farmers grow more food and earn more income, they are better able feed to their families, send their children to school, provide for their family’s health, and invest in their farms.

One way to do this is through biotechnology. Note that I said ONE WAY, not the only way. Nor is this just my opinion. Global sustainability guru Jeffrey Sachs has said this.

One of the most frustrating aspects of the GMO debate is how it is framed. Forget the cranks who dominate the discourse–I’m talking about smart, influential thought leaders who simplistically portray GMOs as a well-meaning technology that hasn’t delivered on its grand promises.

A prime example is Jon Foley’s recent essay, titled, “GMO’s, Silver Bullets and the Trap of Reductionist Thinking.” He starts off:

To begin, GMOs have done little to enhance the world’s food security. Mainly, that’s because GMO crops primarily in use today are feed corn (mostly for animal feed and ethanol), soybeans (mostly for animal feed), cotton and canola. But these aren’t crops that feed the world’s poor, or provide better nutrition to all. GMO efforts may have started off with good intentions to improve food security, but they ended up in crops that were better at improving profits. While the technology itself might “work,” it has so far been applied to the wrong parts of the food system to truly make a dent in global food security.

This is a narrow (dare I say reductionistic) way of looking at food security. Feeding the world’s poor, as Foley knows, also requires improving their livelihoods. It’s about lifting their incomes, helping them break the vicious cycle of poverty. There’s much that goes into that economic development equation but in Africa and other areas of the developing world, the role of commodity crops as an income generator for small farmers is crucial.

To cite one example, look at what happened after Bt cotton was introduced in India. (I’m not talking about a certain popular urban myth.) Recent studies show that Indian farmers who turned to genetically modified cotton have increased their yields, lowered their input costs and as a result, boosted their household incomes. Does that not contribute to food security?

Nor is this the whole story. As University of California plant geneticist Pamela Ronald notes:

To understand why farmers have embraced GE crops and how they benefit the environment, consider genetically engineered cotton. These varieties contain a bacterial protein called Bt that kills pests such as the cotton bollworm without harming beneficial insects and spiders. Bt is benign to humans, which is why organic farmers have used Bt as their primary method of pest control for 50 years. Today 70–90 percent of American, Indian, and Chinese farmers grow Bt cotton.

Recently, a team of Chinese and French scientists reported in the journal Nature that widespread planting of Bt cotton in China drastically reduced the spraying of synthetic chemicals, increased the abundance of beneficial organisms on farms, and decreased populations of crop-damaging insects. Planting of Bt cotton also reduced pesticide poisonings of farmers and their families. In Arizona farmers who plant Bt cotton spray half as much insecticide as do neighbors growing conventional cotton. The Bt farms also have greater biodiversity.

It’s puzzling to me that such benefits are ignored by GMO skeptics who profess a deep interest in human welfare and more enlightened environmental stewardship.

In his piece, Foley goes on to make additional arguments against GMOs that some agricultural biotech proponents have already responded to.

It’s important to bear in mind that this is a young technology. Sometimes the value of a scientific enterprise is not appreciated until years down the road. Have GMOs lived up to the hype of their most exuberant advocates? No. Does any new technology?

Perhaps the naysayers should check back in five or ten years. Maybe food security for those who need it most will be more strengthened with new advances that will be harder to ignore by the GMO-averse champions of sustainability.

UPDATE: Due to time constraints, my critique of Foley’s piece was narrowly focused. In the comments, David Ropeik makes a good point, which was also raised in a series of tweets (starting here) by University of Wyoming’s Andrew Kniss.

UPDATE 2: Science writer and futurist Ramez Naam has weighed in with his response to Foley’s essay.

UPDATE 3: University of Wyoming’s Andrew Kniss has also put up a post addressing one of Foley’s claims.

View the original article here

Kepler Telescope Discovers 715 New Planets

NASA’s Kepler Space Telescope may be down, but it’s not out, and its data collection is the gift that keeps giving.

Scientists on Wednesday announced the discovery of 715 new exoplanets. As the largest windfall of validated planets the space agency has ever revealed at one time, it doubles the number of planets known to humanity outside our solar system.

All of these planets exist within multi-planet systems similar to our own, and 95 percent are smaller than Neptune. Four are even within the habitable zone, which means they could theoretically support life-giving liquid water on their surfaces.

“We’ve been able to open the bottleneck to access the mother lode and deliver to you more than 20 times the planets than had ever been announced previously,” said Jack Lissauer, planetary scientist at NASA Ames Research Center.

Kepler’s latest delivery opens up fresh territory, allowing astronomers to study both individual planets and their configurations within planetary systems.

Since Kepler launched in March 2009, it has identified more than 3,600 possible exoplanets, but most have yet to be confirmed — a process that requires further observation of each candidate world. To this point, confirming planets has been a laborious, slow process. However, scientists used a new statistical technique to open the bottleneck and find hundreds of new planets with relative ease.

Kepler detects planetary candidates by measuring the brief dimming of a star’s brightness as an object passes in front of it, which is called the transit method. This scientific trick is more than 90 percent accurate, but non-planetary bodies can show up as false positives — like when one star crosses in front of another in a binary system.

The new technique, called verification by multiplicity, allowed scientists to weed out instances that couldn’t possibly have been caused by eclipsing stars, eliminating the false-positive problem.

The multiplicity method relies partly on the logic of probability. Distinguishing between a planet orbiting a star and a star orbiting  a star is difficult. But when a third body appears in a transit signal, the chance it is another star is less than 1 percent. A trio of orbiting stars likely wouldn’t line up the way Kepler likes, with two stars passing directly in front of the third, blocking its light and creating the dips that Kepler sees. So when astronomers see Keplerian evidence of a third body, they can be almost certain they’ve found more planets.

Kepler observed hundreds of stars with multiple planet candidates, and careful study of this sample allowed scientists to verify this next big batch of worlds.

“We built upon a lot of past work that has been vetted and reused by the community,” said Sara Seager, professor of Physics and Planetary Science at MIT. “It has a new aspect to it based on probability.”

The multiplicity technique will help scientists efficiently pore through the remaining two years of data from Kepler, which will likely yield hundreds more verified exoplanets.

Photo credit: Kepler Mission/NASA

View the original article here

Arctic Air Spills South, Southern Air Spills North

Departure from average temperatures for Feb. 27, 2014, as forecast by the GFS model. (Source: Data/image obtained using Climate Reanalyzer™ http://cci-reanalyzer.org/, Climate Change Institute, University of Maine, USA.)

Baby, it’s cold outside — again, especially for residents of the Upper Midwest who’ve been beset with repeated Arctic blasts this winter.

But as in previous episodes, that’s only part of the story, as the graphic above illustrates. It shows the forecast departure from normal temperature over the Northern Hemisphere. Notice that while the eastern half of the United States is shivering, large parts of the higher latitudes are considerably warmer than normal.

Once again a loopy jet stream is to blame. Click on the thumbnail at right to see what it looks like.

The map shows the jet stream as forecast by the GFS model for today. A sharp trough of low pressure has dropped down across much of the eastern half of the United States, opening to door for Arctic air to spill south.

The latest Arctic blast comes on a day when the Royal Society and National Academy of Sciences have released an overview of climate change, written in non-scientific language and targeted at general audiences. I’m sure pundits will use the cold temperatures some people are experiencing in the United States to deride the report. But as the map above shows, they will be telling only part of the story.

The new report addresses the issue of cold snaps in a warming world. Here’s part of what it has to say:

Global warming is a long-term trend, but that does not mean that every year will be warmer than the previous one. Day to day and year to year changes in weather patterns will continue to produce some unusually cold days and nights, and winters and summers, even as the climate warms.

The report provides a clear, straightforward and relatively concise overview of the evidence for climate change, and what’s causing it. I recommend that you check it out, and also pass it along to anyone you know who is puzzled about the issue — including anyone shivering under the latest blanket of Arctic air and wondering what happened to global warming.

View the original article here

Male Goats' Stench Activates Female Goats' Reproductive System

Male goats reek. Yet somehow, their mere presence can turn female goats on. Now scientists think they have figured out how this “male effect” works: They’ve discovered a citrus-scented chemical that males emit that speaks directly to females, activating their reproductive brain region and ramping up their sex hormones.

The study is the first to uncover a single molecule that could be activating the entire female reproductive center, according to the researchers.

Pheromones are chemicals released by the body to trigger particular reactions in members of the same species—in the case of sex pheromones, members of the opposite sex. All mammals have sex pheromones, and they come in two kinds: releaser and primer.

Releaser pheromones trigger behavioral responses in the brains of potential mates. The include things like attraction, for example, but the effects are pretty fleeting. Primer pheromones, on the other hand, have been much harder to pin down. They elicit actual physiological changes in the body that are much longer lasting—things like the release of reproductive hormones responsible for ovulation and menstruation.

But scientists hadn’t been able to isolate or identify these primer hormones in mammals until a team in Japan figured out how.

The researchers determined that the pheromones of interest were secreted from the skin on male goats’ heads. To capture these chemicals, the scientists fashioned custom-made caps for the goats that could adsorb (not absorb) them. Two groups of goats—one castrated and one not—donned the special hats for a week, allowing the researchers to collect and identify the chemicals coming from the goat noggins via gas chromatography-mass spectrometry. The researchers found several chemical compounds coming from the uncastrated goats that were missing from the sterile males. Many of them had never been found in nature before.

Next up was determining if and how the females would react to these chemicals. The researchers used electrodes to monitor neural activity in conscious female goat brains. They looked specifically at the hypothalamus, the particular region of the brain controls hormones, among other things.

When the female goats whiffed some male goat hair in a plastic cup, the scent activated something called the gonadotrpin-releasing hormone pulse generator. That’s a fancy way of saying it activated the master switch for all reproductive hormones. But here’s the kicker: the females’ reproductive systems were also turned on by the chemical compounds isolated in the lab.

One particular compound called 4-ethyloctanal triggered a really strong response, enough so that the researchers are pretty convinced it is the elusive primer pheromone. As further proof, when the chemical is exposed to the atmosphere, it oxidizes to become 4-ethyloctanoic acid—the main ingredient in the stench for which male goats are famous. The researchers think their results, published in Current Biology, could explain the power of the “male effect” in goats and could help us better understand how pheromones regulate reproduction in other mammals, including humans.

Image credit: Dudarev Mikhail/Shutterstock

View the original article here

Swirling Cyclone Bears Down on California

As I write this, California is being lashed by rain and wind from a storm bringing much needed moisture — but which also threatens to cause some havoc in the form of mudslides and flooding.

Here’s how the National Weather Service in Los Angeles described it in their forecast discussion this morning:

A VIGOROUS WINTER STORM WILL AFFECT THE AREA THROUGH SATURDAY. EXPECT RAIN...MOUNTAIN SNOW...GUSTY WINDS...POSSIBLE THUNDERSTORMS...WATERSPOUTS...URBAN FLOODING...AND MUD AND DEBRIS FLOWS NEAR RESENT BURN AREAS. RAINFALL WILL BE INTENSE AT TIMES. A CLEARING AND DRYING TREND WILL START SUNDAY AFTERNOON. CLEAR WITH A WARMING TREND FOR EARLY NEXT WEEK.

Waterspouts?!

In the gallery above, you won’t see any of those. These images are various satellite views of the swirling cyclone that is bringing both relief and risk to California today and through tomorrow.

The first is a visualization of the storm’s cyclonic winds, as forecast by supercomputers. I chose it to lead off the gallery because it really emphasizes the structure of this powerful storm.

The next three images come from the GOES-13 weather satellite. The first is a true-color image of the storm. Next is a picture that shows water vapor over the Pacific. And in the third, North American is seen in the infra-red portion of the electromagnetic spectrum. I included this one because it shows the broader geographic context — and just how huge the storm is.

After the GOES satellite imagery comes two images captured by NASA’s Aqua satellite on Thursday, February 27. The first is in natural color, and it too emphasizes the sheer size of the storm. But I’m also intrigued by the much smaller cyclone-like pattern of clouds to the east, closer to the West Coast.

The second Aqua image is in false-color. Based on light in the visible part of the electromagnetic spectrum and short-wave infrared, this color scheme is good for revealing snow and ice — including small ice crystals in high-level clouds, which appear reddish-orange or peach. (This is the 3-6-7 band combination of Aqua’s MODIS instrument. For more detailed information, go here.)

Lastly, an image showing total precipitable water over the Pacific. The colors give an indication of the amount of atmospheric water vapor from the top of the atmosphere to the surface. It really emphasizes the tropical source of the moisture now dumping on California.

View the original article here

February's Sci-shimi: Chestnuts, Chloroplasts, and Conferences, Oh My!

Welcome to Sci-shimi, my monthly roundup of  great science online! Like a delicious, fresh platter of sashimi, these tasty links are meant to be shared —???????? ! 

This month’s mind-blowing science moment: Meet the woman who developed a way to run 30 blood tests with a single drop.

Best long-read: Resurrecting a forest, in which Carl Zimmer explains how genetic tinkering may help bring back the American chestnut, complete with a time-lapse video:

Best non-science long-read: The dark power of fraternities by Caitlin Flanagan (with the best opening paragraph of all time).

Extra-special shout out to Danielle Lee, butt-kicking science blogger, who was chosen this month as one of the White House’s Champions of Change. Danielle, you rock so hard it’s giving me whiplash!

“That in spite of what we have learned, we can persist in being knowingly and brutally cruel—as inhumane and unfeeling as we once regarded all other animals to be.” Powerful words from Virginia Morell on the Taiji dolphin slaughter.

Who is the best thrower in the animal kingdom? The why—not the who—might surprise you, says Jason Goldman.

Talk about changing for the one you love—lemurs in love smell alike.

Vultures don’t follow dead animals; they wait where animals die, explains Allie Wilkinson.

Stunning photos show the inner workings of fish.

What is a plant without its chloroplasts?

Tiny robots, based on insects, that ARE THE SIZE OF INSECTS.

What does lava look like before it erupts from a volcano? Erik Klemetti explains.

Fish that climb rocks with their mouths.

The real Batman—what a bat skeleton looks like in our size.

The most beautiful animal you’ve never seen, by Rebecca Helm.

Andrew Revkin sums up California’s water troubles, and what is in store for the thirsty state.

So much for The Secret—the powerlessness of positive thinking.

Ferris Jabr delves into the giant minds of elephants.

A golden eagle takes down a deer. Seriously.

Ed Yong explains the mystery behind a graveyard of ancient whales.

Super Mario = quantum physics!

“Suns and beaches doesn’t sound like the stuff of nightmares. But the patient said that these dreams were, in fact, unspeakably horrible.”

Feb was a month of conferences: AAAS, Ocean Sciences, and ScienceOnline Together. Be sure to catch up on the twitter hashtags by clicking the links!

*This* is why I love #scio14. Talk art to me, music, theoretical physics, fame. Tell me why all my assumptions are wrong, tell me. Thank you

— LizNeeley (@LizNeeley) February 28, 2014

Bored kids are turning to twitter to amuse themselves. What does this say about the state of our education system

Cane toads prove they can take the heat, or lack thereof.

Love and hate—kinda the same thing, really.

Kyle Hill explains why the Walking Dead zombies have venom, not a virus

Horrifying image of animal research circulates the interwebs—except that it’s not a picture of animal research at all.

What would Miley Cyrus do (if she was into marine science)? #OceanMiley

Turns out, it’s pretty easy to put Miley on most stock oceanographic photos. Here she is deploying a CTD. pic.twitter.com/hZiA0ispPn

— Kim Martini (@rejectedbanana) February 15, 2014

What is dark energy? Matthew Francis explains.

Flying snakes (minus the plane)

Waste heat is free energy—energy crisis solved?

Academic scandal: more than 120 computer-generated papers have made their way onto the pages of respected journals.

How accurate is the movie Pompeii? Actually, not as far-fetched as you’d think.

Plastic ingestion in sea birds is worse than we thought.

A map that shows how historical human populations mixed.

How do mole get around? They swim through the ground.

Have something to add? Tweet me link suggestions with the hashtag #scishimi!

View the original article here