Friday, September 24, 2010

The prospect for October

Here’s the full-cream version of my Lab Report for Prospect in October.

The IPCC is in a bind. There are good arguments for reforming the way it operates, not least improving the efficiency and transparency of its review process. A recent independent assessment by the InterAcademy Council, representing all the world’s major science academies, agreed with that but concluded that the IPCC’s scientific conclusions are reliable and that it has generally worked well on a shoestring. But should its chair, Rajendra Pachauri, stay? Pachauri has been pilloried for errors that led to unjustified forecasts about melting of the Himalayan glaciers – a bad mistake, but negligible in the grand scheme. He has also been unjustly smeared over alleged conflicts of interest. There is nothing here to warrant resignation
But Pachauri’s leadership during the IPCC’s tribulations of the past year has not been inspiring, and more to the point, all leaders grow stale eventually. A change could bring fresh vigour and restore public confidence. Yet such is the aura of distrust fomented by the smear campaign that it would now be all but impossible for Pachauri to step down without being seen to validate climate sceptics’ criticisms. We are now in a mirror-image reality in which some consider Bjorn Lomborg’s U-turn on the threat of climate change more principled than Pachauri’s steadfast advocacy of the science. A reformed IPCC would be welcome, but there will be no winners.

Although it’s perhaps no surprise that the restoration of federal funding for stem-cell research in the United States under the Obama administration is not plain sailing, no one could have foreseen the oddness of the latest, potentially devastating obstacle. The injunction issued by a district court judge in Columbia against such funding stems from a case brought not by Christian ‘pro-life’ groups, who object to the destruction of human embryos in harvesting new stem-cell lines, but by two stem-cell scientists. James Sherley and Theresa Deisher work on adult stem cells and oppose research on embryonic cells, saying that the adult-cell work is both scientifically and ethically superior.
Outsiders to the US legal system will be baffled that a district judge can, by reinterpreting the meaning of a long-standing constraint on embryonic stem-cell work, force the National Institutes of Health instantly to freeze all funding, plunging work in progress into limbo and ensuring funding chaos months or years down the line. But there it is: Chief Judge Royce Lamberth has decided that the 1996 Dickey-Wicker Amendment to NIH budget legislation, prohibiting funding for research involving the creation and destruction of embryos, in fact must prohibit all embryonic stem-cell work whether or not it destroys or creates embryos. The injunction has been appealed by the US Department of Justice.
The amendment itself is probably here to stay, since it impinges also on abortion, but the current Obama policy had left room for the use, with donor consent, of embryos from fertility clinics that would otherwise be destroyed.
Sherley is a complicated character with an agenda that is hard to read. But the fact that a maverick case in a district court can wreck an entire nation’s research effort at the forefront of medical science is chilling.

Because every month now seems to bring a new complete genome sequence – now mouse-ear cress, now the panda – it might have been tempting at first to greet the announcement of the wheat genome with a touch of ennui. But no longer. Drought and flood have devastated wheat yields in Russia and China. Russia, one of the world’s biggest producers, has now imposed an export ban that has sent wheat prices soaring, threatening the food security of millions of people. The riots in Mozambique over bread prices may be just a taste of what is to come.
This is why the wheat genome sequence is one of the most important so far, and why public access to the data granted by the researchers, led by a team at Liverpool University, is so valuable and commendable. The genetic information should point to shortcuts for breeding of new, hardier varieties, as well as identifying specific genes that might be engineered to improve resistance to drought and disease.
            Why, then, has wheat not been genetically sequenced sooner? The answer is sobering: the genome is not only larger than that of most crops, but is five times larger than the human genome. And some scientists have cautioned that the British work offers just a preliminary first draft: the International Wheat Genome Sequence Consortium says that there is still a lot of work to be done in sorting and ordering the raw data.

The much-vaunted medical benefits of sequencing the human genome itself have just received some vindication from the results of clinical trials of the anti-cancer drug PLX4032. The dramatic potential of the drug for shrinking skin-cancer tumours was reported in August, and is confirmed by a recent paper in Nature. But the real excitement stems from the approach: the drug was developed to target a specific carcinogenic mutation of a gene called BRAF, involved in cell growth. The problem is that there are several dangerous mutations of BRAF alone, and thousands of other genetic mutations that also cause cancer. But the new results show that targeting a particular mutation can be highly effective, hitting only those cancer cells that possess it instead of employing the scattershot attack of current cancer chemotherapies. If many mutant-specific drugs come online, rapid gene profiling of patients could enable them to be given precisely the right treatment, without the debilitating side-effects. That, however, will require the development of an awful lot of new drugs. [See my Prospect article on the problems with Big Pharma.]

5 comments:

Gam said...

^^^ Ugh.

Anyway, how in the world did the wheat genome end up so large? That's a fascinating bit of trivia, I can't help but wonder. Some sort of runaway process?

JimmyGiro said...

@William

Maybe it's the other way around, in that simple systems have more redundancy regarding quantity of useless chromosomes and genes.

Chimps have an extra pair of chromosomes compared to humans; and hermit crabs have hundreds of chromosomes.

Molecular evolution includes increasing the chemical efficiency. This is why men have evolved a small sex chromosome, because they are more evolved than women.

Most women are successful in breading, but only a smaller fraction of men are successful, due to direct competition. Hence over the millennia, man's chromosomes have had more evolutionary testing than females.

Gam said...

I've looked into it a bit. Turns out the wheat genome has undergone polyploidy - genome duplication - a number of times. Common wheat is hexaploid; that is, it has six sets of chromosomes, coming from three different diploid species! So its genome is more-or-less three combined genomes of "normal" wheat species.

In addition, the wheat genome has apparently been subject to many transposable elements. 80-90% of its genome, in fact. If we assume that each of the three species constituting its hexaploid genome were subject to the same exposure of transposable elements, the "true" size of the wheat genome is about 850 million base pairs. ([17b / 3] * .15)

After accounting for transposable elements in the human genome (44%), the "true" size is 1.9 billion base pairs.

(Only a very tiny fraction of transposable elements in the human genome have an apparent function (<0.05%). I am assuming this is the case for wheat as well, but we won't know for a while I suppose. This also does not take into account other types of "junk" DNA.)

Sources:
http://www.genoscope.cns.fr/spip/Triticum-ssp-cultivation-of-wheat.html

http://www.ncbi.nlm.nih.gov/pubmed/17331616

Philip Ball said...

Thanks for looking into that William - my vague impression was that there has been lots of complex natural crossbreeding going on, but I don't know if that would account for this behaviour. In any event, the relative neglect of plant biology compared with animals has always been more of a prejudice than a reflection that there's more to be found in animals.

Anonymous said...

This is a really good read for me. I agree with your conclusions and will eagerly look forward to your incoming updates. Just saying thanks will not just be enough, for the phenomenal clarity in your writing.




teeth whitening at home