Archive 2010

Fresh out: extraterrestrial life _not_ discovered! aimee whitcroft Dec 03

You can thank the rampant speculation caused by NASA’s press release for this blog post’s title1.

[UPDATE: There's now a lot of controversy over the paper, which a number of microbiologists says it's not, um, terribly good...]

Very, very tough little bacteria

Very, very tough little bacteria

And the thing is, the discovery in question is a really awesome and important one.  But it’s also a pretty technical one, and I imagine will leave a lot of people saying something along the lines of ‘meh’.

The discovery is, of course, that scientists have found a strain of bacterium2 which is able to use arsenate instead of phosphate in its biological bits and processes.  To understand why this is awesome, some background…

Background (to be skipped by those who know it)

All of the organisms we’ve come across on earth are made up of the ‘big 6′ – hydrogen, oxygen, carbon, nitrogen, sulphur and phosphorus.  Without any of these, an organism loses its fundamental livingness, and is instead simply a great steaming (or not), pile of failed biochemistry.

If I were in front of a periodic table, I should now point at the element Phosphorus.  With a long wooden stick.  Phosphorus is used in cells in a variety of interesting and essential ways: it forms the backbone of DNA, and is also the ‘P’ in ADP/ATP, the molecules which serve as cells’ energy reservoirs/factories.  Oh, and it’s a heap of other important things as well, including stuff like, you know, proteins.

More pointing at the periodic table now!  Another fascinating thing is that this most marvellous table is not some random agglomeration of elements.  Oh no.  Its structure allows us to make some rather interesting inferences.  For example, elements in a column have a lot in common with each other, and can often substitute for each other in biological processes.  Which is why some critters can use tungsten instead of the very-fun-to-say molybdenum.

Or they can use cadmium instead of zinc.

Or copper instead of iron, for the carrying of oxygen (which is why the blood of some mollusks and bug-type things is green).  Interestingly enough, this substitution breaks the ‘same column’ rule – anyone know why?

And, of course, it’s led to much hypothesizing that it may be possible for life to use silicon instead of carbon3, or, possibly, arsenic instead of phosphorus… The most biologically common form of phosphorus is phosphate, which behaves similarly to arsenate in a number of ways.  The thing is, though, that while arsenic can be substituted for phosphorus in the early steps of some biological pathways, it’s just sufficiently different that later arsenic-based metabolites are unstable.  Which is why it’s toxic: it knocks biological processes over.

Kids: do not try eating arsenic at home (or anywhere else, for that matter)

Main story (those who tuned out, feel free to tune back in)

Right, so!  Some scientists, including NASA people, went out to a lake in eastern California, enchantingly called Mono Lake.  Why?  Well, they were on a treasure hunt.  Or, to be more precise, a bacterium hunt.  Mono Lake is far saltier than usual, alkaline (the opposite of acidic), and contains much higher levels of arsenic than usual as well.  A good place to look for arsenic-using beasties.

They took some of the lake’s sediment and, through various mysterious processes known only to microbiologists (and anyone who cares to read the paper)4, they isolated bacteria from said sediment, and set them to growing in two different mediums – one containing arsenate but no (or very little) phosphate, and one containing phosphate but no arsenate (the control).  And they counted how many bacteria grew.

Now, one would expect the bacteria in the control medium to grow just fine.  That’s what they’re there to do.  But, oh joy!  The bacteria in the arsenate-containing medium (now to be called the As+ group) grew too!  Interestingly, they had a far larger intracellular (‘inside the cell’) volume than did their control friends.  This was due to a number of large vacuoles6 inside the cell ,which the authors theorised might be helping the bacteria to stabilise arsenic toxicity.

They then looked at the cells themselves, to seeing whether the As+ group had actually incorporated arsenic into its structures and functions.  And it had!7 There were clear indications that arsenic had been incorporated into DNA – the As+ group had high levels of arsenic and low levels of phosphorus in its DNA fraction, whereas the control group had low levels of arsenic, but high levels of phosphorus.  It also looks like the As+ group had incorporated arsenic into other of its biomolecules, including proteins and small molecular weight metabolites.

To sum up, then: yes, the beasties certainly prefer phosphorus to arsenic, and grow better in it.  But that’s not the point: it’s the first time anything has been shown to be able to grow without phosphorus!

Feeling the urge to say ‘meh’

Of course, this discovery is very exciting to microbiologists, organic chemists and so forth.  But why would the rest of the world care? A couple of reasons, but let’s tackle the obvious, NASA-promoted one.

Currently, the search for extraterrestrial life hinges is predicated on the assumption that such life will be comprised of the ‘big 6′.  This finding suggests that that may not be the case at all, which in turn expands the scope for our search, by increasing the possible ways in which life might be built.

Which is awesome :)

Secondly, it suggests that even life on earth may have come up with some other interesting solutions to the problem of information storage (currently, we’re most familiar with DNA), and we haven’t been looking hard enough for them.  Which is also pretty exciting.

And so there you have it.  The actual science behind all the hoo-ha.  And some pretty fascinating stuff it is, too.  Congratulations to the lake-wading scientists behind it!

Oh yeah, and you can see some excellent comment on the research, from Kiwi scientists, here.

UPDATE: Something of a rant about embargo breakers.  Thanks to The Sun and The Daily Fail for breaking the embargo on this story yesterday.  What you did was spoil the fun, and hard work of everyone else who had been working on this, and were abiding by the rules.  And you wonder why journalism gets knocked for having low integrity…

‘NOTHER UPDATE: photos from the NASA press conference can be seen here.


1 I mean, seriously, what were they thinking?  They must have known this would cause an absolute sh*tstorm of wild theories.  I’m a huge fan, but this seem a little bit pot-stirring of them…

2 GFAJ-1 of the Halomonoadaceae, to be precise

3 Yes.  Silicon-based life.  Crunchy, and potentially sparkly.  Also, of course, we know that computer chips still use silicon /looks around meaningfully

4 I have.  I’m not going to go into the details, as I fear they will induce snoozing in many of my readers.  My descriptions of the methods used are, therefore, something of a simplification.

5 Phosphate is the most commonly occurring form of phosphate.  Arsenate behaves similarly to it in many ways.

6 A ‘cavity’ inside a cell, surrounded by a single membrane, which contains water, food or other compounds (including waste byproducts from metabolism)

7 UPDATED NOTE: on the recommendation of a commenter, I’d like to stipulate that ‘high’ here is a relative term: it’s a matter of proportionality.  For the full nitty-gritties, read the paper.



Felisa Wolfe-Simon, Jodi Switzer Blum, Thomas R. Kulp, Gwyneth W. Gordon, Shelley E. Hoeft, Jennifer Pett-Ridge, John F. Stolz, Samuel M. Webb, Peter K. Weber, Paul C. W. Davies, Ariel D. Anbar, Ronald S. Oremland (2010). A Bacterium That Can Grow by Using Arsenic Instead of Phosphorus Science : 10.1126/science.1197258

Google launches STEM competition aimee whitcroft Nov 22

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I’ve just received a press release from Google, about a competition which looks kinda cool :)

google teslaOn January 11th, they’re going to be launching the (first ever, as is so common with the company) Google Online Science Fair.  Because of its online nature, it means it can be global pretty easily, and it’s open to anyone from the ages of 13-18.

And I can imagine that the prizes will be pretty cool :) (The release mentions internships, scholarships and other, even better, prizes).

The official announcement will be going out on December 1st (and no, I’m not breaking an embargo here).  Anyone who wants more info, and/or thinks they might be interested in telling others about it, go here and they’ll keep you updated!

Wish I was still young enough to enter…


Oh, and STEM stands for Science, Technology, Engineering and Mathematics

Introducing a new blog: sticK aimee whitcroft Nov 12

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Gosh, what a week :)

sticK v3

Yes, we’re happy to introduce you to our third new blogger, Peter Kerr, whose content we’re syndicating over from his blog sticK – science, technology, innovation & commercialisation KNOWLEDGE. Fascinating subject matter, this.

The name of the blog really says it all, so all we’ll say is ‘Welcome, Peter’!  You can find his content on sciblogs, here.

Introducing a new blog: Infectious Thoughts aimee whitcroft Nov 09

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And, we have another!

infectious thoughts banner 2

We’re pleased as punch (and various other expressions of joy) to introduce our newest blogger, Siouxsie Wiles, to all of you.

She’ll be penning Infectious Thoughts, a blog devoted to skepticism, debunking pseudoscientific medical claims, and other forms of clear thinking.  No doubt, it’ll be covering other subjects too, given that Siouxie is an expert in bioluminescence ‘n stuff.

Welcome, Siouxie!

[And stay tuned for the introduction of a third new blogger later this week...]

Introducing a new blog: molecular matters aimee whitcroft Nov 04

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Hooray!  Adding to our already-fantastic list of new blogs, we’re proud to introduce you to molecular matters.

banner v1

Penned by regular guestwork contributor Michael Edmonds, it’s going to cover all sorts of interesting things: chemistry, pseudoscience/anti-science, science communication, and no doubt a wealth of other subjects.

So, welcome Michael!  We’re glad to have you on board :)

5 ways to gain a lover aimee whitcroft Nov 02


Yes, it is a shameful, shameful misappropriation of a great song, but I couldn’t help myself.

peacock feather

Not even a little bit.

And seriously, there are, apparently, five different styles of flirting.  An ‘inventory’*, if you will.  And what, pray (or, possibly, prey) are they?  Read on, dear reader!


This is based very much in traditional gender roles.  You know, where the men make the first move, and women don’t pursue men.  This means that women (who’re more passive) are less flattered by flirting, and also find it more difficult to get men’s attention.  Men, on the other hand, tend to know women longer before approaching them.  So, basically, all quite introverted.


This is based very much on sexual attraction, and communicating that interest.  Relationships formed as a result tend to be formed more quickly, and have greater emotional and sexual chemistry than some others.


This is all about, well, sincerity.  So it focuses on the creation of emotional connections, and on demonstrating sincere interest in the other person.  Women tend to score higher here, but both men and women think it’s a good way to go about things, and relationships tend to be meaningful,and have good chemistry.


This is mostly flirting for the sake of flirting.  People using this style tend not to have any interest in long-term/important relationships (and so tend not to), but do it because they find it fun and it enhances their self-esteem.


This is very much about being proper and polite.  While sexual flirting is, obviously, not high on the agenda, and people who use this style tend to approach those they like less often, they also tend to form meaningful relationships with people.

The researchers in question looked at over 5,000 people, and were able to discern these five primary categories.  They also found that the physical, sincere and playful styles tended to have more success date-wise, and the physical and sincere styles “correlated with rapid relational escalation of important relationships with more emotional connection and greater physical chemistry” (i.e. they tended to get more serious, faster).

Further, the idea is something like this – your flirting style will probably be influenced by previous relationships of yours.  Being aware of your style could, potentially, help you avoid some of the pitfalls inherent in what the paper so charmingly calls ‘courtship initiation’.  Which can only be a good thing, right?

And in case you’re curious, you can go here to find out what your style is.  I did (although I’m a little unconvinced of the results)…


* Their word.  Not mine :)



Jeffrey A. Hall, Steve Carter, Michael J. Cody, & Julie M. Albright (2010). Individual Differences in the Communication of Romantic Interest: Development of the Flirting Styles Inventory Communication Quarterly : 10.1080/01463373.2010.524874

How fast to shake to get dry? Science answers… aimee whitcroft Oct 21


It’s a difficult subject, this.

shaking dog

And probably too punworthy for me to be able to help myself (although I shall try).

Some enterprising scientists have discovered the optimal oscillation needed by a hairy beastie shaking itself dry.  And by oscillation, of course, I mean ‘shaking of the body’. Or, possibly, ‘booty’.

They filmed a bunch of dogs shaking themselves as a means of water dispersal*, and had  a look at the results, which for labrador retrievers was 4.3 Hz.

This led to a lovely model in which they hypothesized that the oscillation necessary is R^0.5, where R is the radius of the body**. Which means that smaller animals will have to shake faster.  A mouse must shake faster than, say, a woolly mammoth.

Of course, and as with all science, the prediction above needs to be tested, and this is what our friendly scientists did.  They looked at mice, cats, bears, and no doubt a plethora of other beasties, and found that yes, the larger the animal, the lower the Hz.

To be more specific, mice come in at 27 Hz, cats at 6Hz, and bears at a stunning 4 Hz.  (I still want to see a woolly mammoth shaking, for the humour/awe as well as the science)

They also found that the equation is a little different from that originally conceived, with the optimal oscillation being closer to R^0.75 = driest beastie possible.

Thought points:

How exactly does one define R?  Does it include or exclude fur?

To what practical use could we put this?  A device to optimally oscillate string mops?  How fast one should shake one’s head to dry our hair?  (Or, for that matter, how best to head bang to ensure maximum sweat coverage of those around one?)

Perhaps there’s a use for salad spinners?

And see?  I managed not to pun too much (she said drily)


I clearly like things to do with fluid dynamics, given that I’ve also posted about teapots


*One wonders if they also measured the oscillation frequency necessary to make any humans in the vicinity scream the loudest.

** Reasoning as follows, for those who’re interested.  Water is stuck to the animal’s fur due to surface tension between water and air.  In order for the water to become unstuck, enough centripetal force*** needs to be generated to overcome this.

*** Yes yes, I know.


The arXiv article I based this on.  As usual, the authors of these articles are legendary in their ability to explain this sort of stuff.  Note their wonderfully facepalm-worthy use of ‘paws.

Brilliant photos of small things aimee whitcroft Oct 21

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Being a large fan of all things small, particularly when one is able to take photos of them, I bring you this:

Credit: Jocelyn Chang. An image of a bryozoa, from the Nikon Small World competition (2010)

Credit: Jocelyn Chang. An image of a bryozoa, from the Nikon Small World competition (2010)

Yes, the results for this year’s Nikon Small World competition are in.  Each year, the competition takes in entries of the best microscopy on the web, and then hurls awards at the ones it likes the most.

Or something.

I remember spending hours happily closeted with a very large and expensive fluorescent  microscope, taking perdy pictures of the neural cells with which I was playing for my Honours degree.  At the time, my supervisor mentioned that microscopists were in increasing demand overseas, and whenever I see images like this, I wonder whether I should have become one of these.

After all, it’s photography with science.  Two of my bestest things.

So, what’s your favourite image?


I also came across this fabulous video of an octopus being very balletic…

YouTube Preview Image

A challenge! aimee whitcroft Oct 14

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Greetings, all!


Ah, the R62. The world's longest wine route (and most beautiful road), in the gorgeous Klein Karoo

Before explaining the subject of this post further, I thought I’d explain that my absence hasn’t been due to my deciding no longer to pen sciencey things, but can instead be put down to the fact that I have spent the last three weeks in South Africa.  Which means I now have a tan :)

And it is with this absence in mind that I now put out the challenge (or request, depending on how you look at it).  I have been sadly, sorely, out of touch with everything happening in the world of science and tech.  Being up to date would be nice.  However, given that I have a day job and all, I am unable to sift through the last three weeks of news.

Which is where all of you come in: what’s happened in the last three weeks?  What were the most important/amusing/fascinating stories and discoveries in this time period?  Please keep your answers short and to the point, and, of course, haikus are always welcome.

Physicists aimee whitcroft Sep 16


Stunning timing!


xkcd’s newest strip is on the subject of physicists.    Why am I wittering about timing?  Well, given that I’ve just written a post about physicists explaining what’s going on, it’s pretty awesome synchronicity.

Oh yes, and we do laughing at them a little, as well :)

[HT: Jason for sending me the link, with the simple message 'apropos']

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