Geneticists have found a way to alter the sexual preference of lab mice. When they bred mice who had one gene deleted, the females declined male companions and preferred instead to court other females, according to a study published yesterday in BMC Genetics. But whether these results have any implications for humans is still far from clear.

Chankyu Park and his team at the Korea Advanced Institute of Science and Technology deleted the female’s fucose mutarotase gene and, as a result, changed the brain’s exposure to enzymes that control brain development.

The gene, fucose mutarotase (FucM), is responsible for the release of an enzyme by the same name, and seems to cause developmental changes in brain regions that control reproductive behaviors. The mice without the enzyme would refuse to let males mount them, and instead tried to copulate with other females. [AOL News]

The enzyme typically works with a protein to prevent a build-up of the hormone oestrogen in the mouse brain; extra oestrogen causes parts of female mice brains to develop like typical male mice brains. Explains Park:

“The mutant female mouse underwent a slightly altered developmental programme in the brain to resemble the male brain in terms of sexual preference.” [The Telegraph]

Park has not found a “gay gene”–it’s impossible to tell at this stage what relationship, if any, this study has with human sexual preferences. For one, the hormone that “masculinizes” human brains is testosterone rather than oestrogen, and the protein block isn’t the same either. Still, Park hopes to investigate further to see if the study will shed any light on human sexuality.

Now, Park and his colleagues are hoping to use gene screening studies to find out whether fucose mutarotase has any association with sexual orientation in humans. He admits this research may be “very difficult”, partly because it will not be easy to find a suitable number of volunteers. [New Scientist]

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Image: Wikimedia

A little stress can do a mouse good, a new cancer study suggests.

Matthew During wanted to see whether stressing out mice by messing with their environment would affect the rate of tumor growth. So, for a study that now appears in Cell, he and his team divided up their mice into two groups. Some mice lived quiet, peaceful lives in cages shared between five mouse roommates, while the other group lived in a stressful cluttered cacophony, where the cages held 18 to 20 animals plus numerous distractions and challenges like toys, mazes, and wheels.

Mice were then injected with tumor cells, which led to malignancies in all of the control animals within 15 days… The rate of tumor formation in animals living in the enriched environment was significantly delayed, and 15 percent had not developed tumors after nearly three weeks; when tumors were visible, they were 43 percent smaller than the lesions on control animals [Scientific American].

Because the “enriched environment” gave those mice so much more to do, an obvious conclusion would be that it’s the uptick in physical activity—not the effect of added stress—that kept tumors at bay. So During’s team tested the mice to see if just giving them more time on the running wheel, independent of the other factors, was enough to see the effect. It wasn’t.

Physical exertion alone also didn’t inspire the chemical changes that the team thinks could be responsible for the anti-cancer effects they saw.

The ‘enriched’ mice, the researchers found, had slightly raised levels of stress hormones, but the most striking physiological change was markedly reduced levels of the hormone leptin, known to regulate appetite. Blocking leptin abolished the effects of enrichment, suggesting that the hormone was key to the pathway that led to the anti-cancer effects [Nature].

The linchpin behind all this seems to be a protein called brain-derived neurotrophic factor (BDNF), which increased in the enriched-environment mice. Further tests by the team suggested that the protein spurred the drop in leptin and boosted the immune system, which would be connected to the tumor reduction.

That’s fine for mice, but what about us?

Whereas most people live in fairly safe environments, with plenty of food and some degree of social interaction, “our data suggests that we shouldn’t just be avoiding stress, we should be living more socially and physically challenging lives,” During says [Scientific American].

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Image: Wikimedia Commons

Has anybody thought that the end of the mammoths and other large mammals like the saber-toothed tiger looks a lot like the demise of the dinosaurs?  Mass extinction events are one of my personal interests, especially when they involve a celestial body or event.  We have a lot of evidence to support an impact event as a contributing factor to the end of the dinosaurs, but what about the large mammals about 12,000 years ago?

Smilodon, the Saber-Tooth Cat - Image by Wiki user Wallace63- on display at the American Natural History, New York - all rights reserved

Now, guess what:  You are not going to believe this, but scientists working in Antarctica have found a LARGE distribution of hexagonal nanodiamonds at the level about 12,000 years ago.  We only get hexagonal nanodiamonds in an impact event, they aren’t formed naturally on Earth.  They’re called “presolar grains”, and they’re probably formed in the supernova of red giants, like Betelgeuse.

No crater has been found to correspond with the findings in Antarctica, but the geological record shows a “black mat” (containing Iridium) at the level of about 12,000 years ago, so it looks like something happened.

Dodo Bird - remake of a 1626 painting by Roelant Savery - copyright expired

There have been many mass extinctions in Earth’s history.  Over 98% of all the species ever living have gone extinct.  We’re in the middle of an extinction event right now, the Holocene extinction (possibly having it’s origins 12,000 years ago).  From 1500 to 2009, we’ve documented the loss of 875 species.  Since extinctions often go unnoticed, some scientists think that we may have lost up to 2 million species.  The Species-area theory puts the loss at 140,000 species annually.  The UN Convention on Biological Diversity estimates that species are being lost faster than they are discovered… at the rate of three per hour.  Yes.  Three per hour, the worst extinction in millions of years.

Impact nanodiamond - STEM image - image by Wiki User "NIMSoffice" - all rights reserved

Now that I have your attention, the Younger Dryas event postulates that we had an air-burst comet over the North America Great Lakes Area ca 12,900 BP  (“BP” just means “before present”), much like the Tunguska Event.  A Paleo-Indian culture called the Clovis Culture was also lost during this event.  The Clovis Culture has long been blamed for the loss of the mammoth due to over-hunting; a good hypothesis, considering we of European descent almost wiped out the buffalo due to stupidity and greed… but look at Indigenous people in recorded history.  They don’t usually over-hunt like that… they have more respect for their environment.

Wooly Mammoth - by Benjamin Waterhouse Hawkins - copyright expired

Scientist are taking closer looks at past extinction events, and it looks like a celestial event may be a contributing factor in more of them than previously thought.  What’s exciting is the ice record in Antarctica.  It’s a frozen record of what the environment was like thousands of years ago, and as we get better at understanding the record, we learn more about the past.

What do you think about it?  I’d be very interested in hearing your considered opinion.

Facing enemy gunshots, which would you choose: the old stand-by Kevlar vest, or a new “liquid” suit? Ongoing research at BAE Systems suggests you might be wise to pick the latter. Recent tests, BAE researchers suggest, hint that a combination of liquid and Kevlar layers might stop bullets more quickly and keep them from going as deep.

BAE tested each material’s mettle by blasting them will ball bearings fired at over 600 miles per hour from a gas gun. The video, available on the BBC site, shows a side-by-side comparison of 31 layers of Kevlar and 10 layers of Kevlar combined with the liquid.

Apparently, the liquid has a secret recipe for how it sticks together to absorb the bullet’s force. Watching the video, it seems like non-Newtonian fluids are at work (everyday examples of non-Newtonians include ketchup and peanut-butter). Though a cornstarch and water mixture stiffens when you punch it, it’s hard to see cornstarch making strides on the battlefield.

Even if he can’t divulge the details, Stewart Penny, a business development manager at BAE, told the BBC that the material is seriously sticky.

“It’s very similar to custard in the sense that the molecules lock together when it’s struck.”

BAE also believes that the new liquid suit will be less cumbersome than traditional Kevlar suits–reducing soldiers’ fatigue and also, given that it’s liquid, improving their flexibility in the field.

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Image: flickr/ The Ratt