h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

A few days ago I cleared out the raspberry patch and tied up the new shoots to the wires.

Due to my serious neglect, several of them ended up with many/most of their leaves facing the wrong way - directly in most cases.

Previously, I'd noticed various plants' leaves righting themselves from awkward positions.
In this case, so far most of them have righted themselves - from what I thought would be pretty well impossible attitudes.

So, what's the mechanism?

Hormones.

Leaves have photoreceptors pretty much all over. When light is being detected away from the upper surface of the leaf (which, of course, does the most photosynthesis) then the plant releases growth hormones targeted at receptors on the other side of the leaf. These sides produce new structural cells quickly, pushing the leaf into the right direction.

B

Thanks, Mu Beta

>>Leaves have photoreceptors pretty much all over<<

That's something I hadn't realised but should have - ignoring the subtleties, blinded by the obvious.

Rod

Quite right, the phenomenon is called phototropism. Roots have the same thing and it pushes growth away from the light.

One of my colleagues her at Cardiff devotes his research activities to understanding all of this.

http://www.cardiff.ac.uk/chemy/contactsandpeople/academicstaff/richter-gerald.html

(might be a wee bit technical )

We're actually working with him in one project to harness photoactivatable proteins as molecular switches - light makes them changes shape so we're working to connect this shape change in order to control another protein's function. That way, in the future, you might be able to kill, say cancerous cells, by shining light on them. At least that's the endgame.

Ooh! Say it again, Orcus! Did I get one right?

B

So can you make bio light switches yet? That'd be cool, a little puddle of cells that turn your house lights on when it gets dark!

Oh we have several photo-switchable systems in our repertoire.

The trouble is that they're not like your light switch at home. Imagine a lightswitch that you switch it, but only 70% of it actually switches and all of that switches itself off again over periods ranging from seconds to hours.

Not exactly reliable as yet

It's not remotely translateable technology yet either - strictly academic for the short-mid term future I think.

And yes B, correctamundo

"strictly academic for the short-mid term future"

Tut, when you can do some proper science Orcus? You know, practical stuff that'll help you take over the world?

Ah this isn't me - I don't work on these projects. My shrink-ray is my main priority