Friday, August 31, 2012

Two more by Ed Yong this week

A great backgrounder on mites and another chapter in the gene-transfers-among-bacteria story. It's been quite a productive week for Ed! Quality and quantity.

Everything you never wanted to know about the mites that eat, crawl, and have sex on your face


Top of the story:
Everything you never wanted to know about the mites that eat, crawl, and have sex on your face
New Scientist published a story yesterday stating that rosacea – a common skin disease characterised by red blotches on one's face – may be "caused" (more on this later) by "tiny bugs closely related to spiders living in the pores of your face." Tiny bugs that "crawl about your face in the dark", lay eggs in your pores, and release a burst of faeces when they die.
This is the terrifying world of the Demodex mite. And by "terrifying world", I mean your face. For anyone who wants to know more, and who isn't currently clawing at their cheeks or bleaching their head (health tip: don't), here's everything you never wanted to know about your face-mites.
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Say hello to my little friend
Mites are relatives of ticks, spiders, scorpions and other arachnids. Over 48,000 species have been described. Around 65 of them belong to the genus Demodex, and two of those live on your face. There's D.folliculorum, the round-bottomed, bigger one (top image, above) and there's D.brevis, the pointy-bottomed, smaller one (bottom image, above). These two species are evolution's special gift to you. They live on humans and humans alone. ...

Harmless soil bacteria are trading weapons with those that kill us

There are bacteria in the soil that can resist our antibiotics. That's predictable – these drugs are our versions of natural compounds that bacteria have been assaulted with for millions of years. Of course, they would have evolved resistance.
There are also disease-causing bacteria in our hospitals and clinics that can resist our antibiotics. That's predictable too – we expose ourselves, often unnecessarily, to high doses of such drugs. Of course, bacteria would have evolved resistance.
Here's something fascinating though: some of the genes that confer resistance to the harmless soil bacteria are exactly the same as the ones that confer resistance to the devastating clinical ones. Exactly the same, DNA letter for DNA letter.
This new discovery, by Gautam Dantas, suggests that environmental bacteria may be supplying genetic weapons to the ones that kill us (or the other way around). I've written about this secret arms trade for The Scientist. Check it out.



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