Posted on 3 January, 2008 by Ed Yong
In the meadows of Europe, colonies of industrious team-workers are being manipulated by a master slacker. The layabout in question is the Alcon blue butterfly (Maculinea alcon) a large and beautiful summer visitor and its victims are two species of red ants, Myrmica rubra and Myrmica ruginodis.
The Alcon blue is a ‘brood parasite’ – the insect world’s equivalent of the cuckoo. David Nash and European colleagues found that its caterpillars are coated in chemicals that smell very similar to those used by the two species it uses as hosts. To ants, these chemicals are badges of identity and so similar are the caterpillars that the ants adopt them and raise them as their own. The more exacting the caterpillar’s chemicals, the higher its chances of being adopted.
The alien larvae are bad news for the colony, for the ants fawn over them at the expense of their own young, which risk starvation. If a small nest takes in even a few caterpillars, it has more than a 50% chance of having no brood of its own. That puts pressure on the ants to fight back and Nash realised that the two species provide a marvellous case study for studying evolutionary arms races (which I’ve blogged about before here).
Theory predicts that if the parasites are common enough, they should be caught in an ongoing battle with their host, evolving to become more sophisticated mimics, while the ants evolve to become more discriminating carers. The two species make a particularly good model for this because their geographical ranges overlap in a fractured mosaic.
Filed under: Animal behaviour, Animal evolution, Animal kingdom, Evolution, Evolutionary arms race, Insects & arthropods, Invertebrates, Mimicry & camouflage, Parasites | Tagged: Alcon blue butterfly, ants, brood parasites, butterflies, Evolution, insects, Myrmica, science | 1 Comment »
Posted on 11 December, 2007 by Ed Yong
Evolution can sometimes be seen as a futile contest. Throughout the natural world, pairs of species are locked in an evolutionary arms race where both competitors must continuously evolve new adaptations just to avoid ceding ground. Any advantage is temporary as every adaptive move from a predator or parasite is quickly neutralised by a counter-move from its prey or host. Coerced onward by the indifferent force of natural selection, neither side can withdraw from the stalemate.
These patterns of evolution are known as Red Queen dynamics, after the character in Lewis Carroll’s Through the Looking Glass who said to Alice, “It takes all the running you can do, to keep in the same place.”
These arms races are predicted by evolutionary theory, not least as an explanation for sex. By shuffling genes from a mother and father, sex acts as a crucible for genetic diversity, providing a species with the raw material for adapting to its parasites and keep up with the arms race.
Watching the race
We can see the results of Red Queen dynamics in the bodies, genes and behaviours of the species around us but actually watching them at work is another matter altogether. You’d need to study interacting species over several generations and most biologists have neither the patience nor lifespan to do so.
But sometimes, players from generations past leave behind records of the moves they made. Ellen Decaestecker and colleagues from Leuven University found just such an archive in the mud of a Belgian lake.
Filed under: Animal evolution, Animal kingdom, Bacteria, Evolution, Evolutionary arms race, Invertebrates, Parasites | Tagged: Daphnia, Pasteuria, Red Queen, science, water flea | Comments Off on Mud time capsules show evolutionary arms race between host and parasite
Posted on 8 December, 2007 by Ed Yong
Stem cells have long been hyped as the shiny future of medicine. Their ability to produce to every type of cell in the body provided hope for treating diseases from Alzheimer’s, to Parkinson’s to stroke, by providing a ready supply of replacement cells. Despite years of slow progress, we are now tantalisingly close to turning this hype into reality and a new study suggests that the dawn of promised stem cell treatments is getting closer.
For the first time, scientists have cured mice of a genetic disorder called sickle cell anaemia using personalised stem cells reprogrammed from cells in their tails. The study is a powerful ‘proof-of-principle’ that reprogrammed stem cells could one day fulfil their potential in fighting human disease.
The personal touch is of the utmost importance. It’s no good just giving someone any old stem cells. Genetic differences between the donor and recipient could cause problems in the long-term and trigger attack and rejection from the hosts’ immune system in the short-term. The trick is to convert a patient’s own cells into personalised stem cells for their own private use.
Last year, a group of Japanese scientists found a way to do this in mice and produced “induced pluripotent stem cells” (iPSCs) that were very similar to embryonic stem cells. And just last month, I blogged about two breakthrough papers which showed that human cells could also be reprogrammed into iPSCs.
Now, Jacob Hanna and colleagues from the Whitehead Institute for Biomedical Research, the University of Alabama and MIT, have used these reprogrammed cells to cure a genetic disease – sickle cell anaemia.
Filed under: Health & Medicine, New treatments, Stem cells | Tagged: embryonic stem cells, gene ther, induced pluripotent stem cells, reprogramming, sickle cell anaemia, Stem cells | 4 Comments »
Posted on 29 November, 2007 by Ed Yong
I’ve written an article for the Economist about a new strain of the antibiotic-resistant “superbug” MRSA (methicillin-resistant Staphylococcus aureus) that infects large numbers of farm pigs and can jump into humans.
The strain was first found in pig farms in the Netherlands and may be picking up new resistances from their porcine hosts because of the large amounts of antibiotics used to medicate livestock.
The piece is in the Science and Technology section of the November 29th issue of the Economist (out in the UK tomorrow) but you can already read it online. I’m pretty excited about this – it’s certainly the most prestigious magazine I’ve had the opportunity to write for.
Filed under: Bacteria, Drug resistance, Health & Medicine | Tagged: Economist, MRSA, Netherlands, pigs, staph, Staphylococcus aureus, zoonosis | Comments Off on MRSA gets piggyback from livestock to humans
Posted on 23 November, 2007 by Ed Yong
Potential is a sad thing to lose. Have you ever thought that it would be great to return to your childhood, when your options seemed limitless and life hadn’t taken you down increasingly narrow corridors of possibility? Wouldn’t it be great to rewind the clock and have the choice to start over?
While that’s still the stuff of science-fiction, for some cells in your body it may soon be science fact. In one of the most exciting scientific breakthroughs of the year, two groups of scientists have found a way of turning adult human cells back into the stem cells of embryos.
Creating embryonic stem cells
Embryonic stem cells are the embodiment of potential. Armed with a trait called ‘pluripotency‘, they can give rise to every single type of cell and tissue in the body, renewing themselves indefinitely while their daughters take up the mantle of nerves, muscles, blood and more.
For years, stem cells have been touted as the Holy Grail of modern medicine. Within their membranes lies the potential to understand how we develop, test new drugs and most importantly, provide replacement cells to treat Alzheimer’s, Parkinson’s, spinal cord injuries, diabetes, stroke and more.
Filed under: Genetics, Health & Medicine, New treatments, Stem cells | Tagged: , embryonic stem cells, induced pluripotent stem cells, pluripotency, reprogramming, Stem cells, Thomson, Yamanaka | 1 Comment »