Third cousin couples have the most children and grandchildren

Blogging on Peer-Reviewed ResearchMarriage between closely related cousins is a heavy taboo in many cultures and its critics often cite the higher risk of genetic diseases associated with inbreeding. That risk is certainly apparent for very close relatives, but a new study from Iceland shows that very distant relatives don’t have it easy either. In the long run, they have just as few children and grandchildren as closely related ones.

Shuffling the genetic deck

Indian marriageSex chromosomes aside, every person has two copies of each gene, one inherited from their father and one by their mother. Not every gene will be in correct working order, but there’s a good chance that a faulty copy will be offset by a functional one from the other parent.

However, if two parents are closely related, there’s a higher-than-average chance that they will already share some of the same genes and a similarly increased chance that their child will receive two defective copies. That can be very bad news indeed and in cases where important genes are affected, the results can include miscarriage, birth defects or early death.

Sex, then, is a shuffling of their genetic deck and theoretically the more closely related the partners are, the greater the chance that their child will be dealt a dud hand. And yet, some studies have found that some closely related couples actually do better than distant relatives in terms of the number of children they manage to raise. This trend is certainly unexpected and the big question is whether it is the result of biology or money.

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Editing Ebola – how to tame one of the world’s deadliest viruses

Blogging on Peer-Reviewed ResearchIn a list of the most dangerous jobs in the world, ‘Ebola researcher’ must surely rank near the top. But if new research is anything to go by, it may soon fall several places. An international team of scientists have recently found a way to neuter the virus, making it easy to study without risking your life. The altered virus looks like Ebola and behaves like Ebola, but it can’t kill like Ebola. It should make studying the virus easier and most importantly, safer.

Ebola virusThe Ebolaviruses and their cousins, the closely related Marburg family, have a chilling and deserved reputation. In some outbreaks, 90% of those infected die from massive blood loss. There is no approved antiviral treatment. There is no vaccine. And given that it’s almost a rite du passage for infectious disease scientists to contract the contagion they study, working with Ebola is a delicate affair.

Maximum protection

Ebola research requires the highest level of safety possible – the “Biosafety Level-4” laboratory. The stand-alone facilities are designed to be easily sealed and impervious to animals and insects. All routes in and out, including all pipes and ventilation, are peppered with multiple airlocks, showers and rooms designed to prevent any chance of escaping viruses.

There are very few people who are qualified to work in such a prohibitive environment and those that do have to wear a Hazmat suit at all times and breathe from a self-contained oxygen supply. No wonder then that the majority of Ebola research doesn’t actually use live, infectious viruses.

Scientists must instead settle with isolated proteins, proteins shoved into other, less harmful viruses or even “virus-like particles”. But these artificial systems are different to the virus proper, and using them is like staring at a complex machine through a cobweb-covered keyhole. Peter Halfmann from the University of Wisconsin has found a way around this, opening the door for scientists to get a proper look at the virus.

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Evolutionary arms race turns ants into babysitters for Alcon blue butterflies

Blogging on Peer-Reviewed ResearchIn 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.

Myrmica rubra and an Alcon blue butterfly caterpillarThe 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.

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Mud time capsules show evolutionary arms race between host and parasite

Blogging on Peer-Reviewed ResearchEvolution 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.

Mud time capsules show evolutionary arms race between host and parasiteThese 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.

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Sickle cell mice cured by stem cells reprogrammed from their own tails

Blogging on Peer-Reviewed ResearchSickle cell mice cured by stem cells reprogrammed from their own tailsStem 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.

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MRSA gets piggyback from livestock to humans

Blogging on Peer-Reviewed ResearchMRSA gets piggyback from livestock to humansI’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.

Human skin cells reprogrammed into stem cells

Blogging on Peer-Reviewed ResearchPotential 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?

Human skin cells are reprogrammed into stem cellsWhile 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.

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