Genetic weapon developed against honeybee-killer

[Adam]

From the BBC...

Researchers have developed a genetic technique which could revitalise the fight against the honeybee's worst enemy - the Varroa mite.

http://news.bbc.co.uk/earth/hi/earth_news/newsid_9306000/9306572.stm


There's also a link to the Scottish Beekeepers web site there. Why's that then? :confused:


Adam

[gavin]

'cos its the best national beekeeping association in the UK?! Naw ... Alan Bowman is in Aberdeen, that may help. Also he had SBA support for a small project on Varroa but it must have been a precursor to this RNAi work I think.

I'm with Francis Ratnieks on this. It is a long way from being an effective and accessible treatment, and sounds like it would have to be applied to unsealed brood to be effective. I'd rather that we worked on our bees (by normal breeding, not by new techniques such as RNAi) and helped them overcome Varroa by themselves.

RNAi? RNA carries the message of the gene to bring about the effect of the gene, usually by coding for a protein of some kind. The 'i' stands for interference, and this work relies on the organism's RNAi mechanisms to suppress viruses, turning it on the targeted gene instead.

Huge potential there to do things like switch off genes involved in cancer, but there have been some conspicuous withdrawals from the technology after massive investment. There has been speculation that the effect is transitory, but I don't know enough about it to tell if that is true or not.

Gavin

[chris]

Watch out Gavin, José McBeevé may get wind of it :eek:

[gavin]

Why do you think that I was careful to distance myself from the technology?! :p

No, magic bullets sound fine and dandy, but they aren't always appropriate or sustainable. There is something similar going on in the States with bee viruses.

G.

[gavin]

So, what's this all about I hear you ask? The fundamentals of life revolve around (at one level anyway) the DNA sequence. Here sit the genes, they get copied to an RNA sequence, and the cell's machinery takes it from there. Usually the RNA sequence is used to 'translate' the code into a string of amino acids, ie a protein.

Some viruses come as an RNA sequence, and others come as DNA but make lots of RNA copies. Cells have mechanisms to suppress those RNA molecules, very necessary as otherwise once a virus gets in the organism would be doomed.

RNA suppression of host genes also occurs as a natural mechanism during development or in response to a challenge of some kind. There is a whole industry devoted to exploiting what promises to be a very powerful technology, and the thought of being able to turn down misbehaving genes has got cancer research entrepreneurs wetting themselves at the prospect of new therapies particularly dramatic, effective, and highly specific 'fixing' of genes going wrong. Also the technology might provide a cure for horrifying genetic diseases such as Huntingdon's. However there are signs that the early promise may have been a bit over-optimistic. See later.

If you'd like a technical but good animation summarising RNAi, try here:

http://www.nature.com/focus/rnai/animations/animation/animation.htm

What is the new paper about? Alan Bowman and his collaborators have dunked Varroa mites in the trigger for RNAi, a double-stranded RNA molecule, and managed to switch off the gene which the dsRNA was designed to affect. So, in theory, they could switch off something crucial in the Varroa mite and cause its demise. 'All' they have to do now is find a good gene target and devise a system to deliver the dsRNA to the mites.

That isn't going to be easy. You'd have to deliver enough dsRNA (which isn't that stable) into the brood food of bee larvae shortly before sealing, as that is when the mite jumps in to start her family. Or somehow get it into the bee haemolymph without damaging the bee.

However, there are safety and economic considerations. Is RNAi safe? No-one really knows, but there have been some worrying reports. Does it sometimes affect other genes, the ones which are not the direct target? Yes, it seems so. That huge surge in interest a few years ago in using the technology to cure cancer, how's that going? Well, folk are talking about trials, but ....

- Roche spent $500 million (yes, half a billion dollars!) on developing the technique, and now they have given up. Thrown in the towel, walked away.

- 'off target' effect have been detected in fruit flies

- mice treated with RNAi for a virus keeled over and died a few weeks later, simply a toxic effect perhaps to do with diverting important parts of the cell's machinery

So are we ready to give up cheap and effective remedies like oxalic acid and thymol for what will be an expensive method with uncertain effects on bees and even human consumers of honey and pollen? I doubt it.

But perhaps these concerns are over-blown and it will become a safe, inexpensive and very precise therapy. No-one knows.

all the best

Gavin

URLs for the three bullet points above:

http://www.nature.com/news/2010/101123/full/468487a.html
http://www.the-scientist.com/news/display/23495/
http://www.the-scientist.com/news/display/24678/

[Jimbo]

Hi Gavin,

Not only the Cancer boys wetting themselves but add the Cardiac and Stoke boys to name a few can be added to that list. The latest I have heard is the problem of targeting the defective genes and the method of delivery that is a problem. If they get the technology to work do you think we are ready for a bit of genetic modification in humans as well as bees?

[Neils]

/tinfoil hat
If you can switch off "bad genes" in humans and "good genes" in varroa what stops you switching off "good genes" in humans too?

Wasn't this the macguffin in the last spooks series thinking about it? A genetic weapon that targeted ethnically unique genes; which subsequently turned out to be unworkable, they'd just neglected to let that bit slip.

[gavin]

Spooks was one of my favourites and yes, that storyline was very relevant.

On the gene targetting, that is the question, not the $64k one but the $640m one.

Three reasons I can think of for worrying about non-target effects:

1) the specific Varroa gene sequence you pick to turn mites to self-destruct mode might have enough similarity to have an effect on bees too. Just maybe. No doubt an expert could look at the sequence and tell you if that is likely. Probably not the biggest concern, but bees would have to have intimate contact with the treatment.

2) the method relies on cutting RNA into 25-base chunks which then propagate the signal. Given that 25 bases is quite a small number, there is a possibility that your specific dsRNA might affect the workings of some other genes in the same organism, or just maybe in one that comes into contact with your dsRNA treatment. Such as the beekeeper. Likelihood? I find it very hard to say, but if it does happen the effects could be important.

3) By forcing the DICign and SLICing mechanism to do your bidding, you may expose the organism to other problems. For example (and I'm being theoretical here) what if the process keeps 'jumping genes' (our own genomes are riddled with them, usually called transposons) under control and you divert that surveillance system so much that they run riot. What then?

So .... I'm not an expert at all, but there are some possibly low-likelihood worries and if they come to pass they could be high-impact problems. Don't get too carried away about this issue about the effect on other organisms, as RNA is quite a fragile thing and might not last long when exposed to complex environments. And, being beekeepers, we ought to have a rational, thoughtful, informed, non-hysterical look at the issues without getting too excited and hyper about it all, shouldn't we?!

G.

[Neils]

Stuff
I'm starting to recognise that look in myself that I see in others when I try to explain database design to them or how that bit of code works. :D


And, being beekeepers, we ought to have a rational, thoughtful, informed, non-hysterical look at the issues without getting too excited and hyper about it all, shouldn't we?!

G.
First time for everything I guess.

[Adam]

Blimey, I didn't expect the Spanish Inquisition! Too much information after a 6 hour meeting today me thinks!

Nelli, I agree, a rational informed debate would be a good but rare thing. Any developments would be a long long way off so we are currently stuck with Thymol, Oxalic Acid and small cells (As Michael Bush suggests) and IPM.

[gavin]

You should always expect the unexpected!


http://www.youtube.com/watch?v=gldlyTjXk9A

[Trog]

Behave, Gavin, or I'll fetch the comfy chair ;)