This week on Sunday Science: the surprising shared evolutionary history of cephalopod arms and ours; a radically improved PET scanner promises revolutionary new scans; how deer antlers are providing insights into bone cancer; folic acid supplementation and a rock-eating shipworm….

A rather neat story about the evolution of limbs (overviewed nicely in that NYT article). Despite the vast differences between insect wings and mice legs, for example, it’s been known for a while that a lot of the underlying genetic networks that pattern these limbs, coordinating along a set of axes, during embryo development have been conserved and only modified over time, rather than evolving a completely new system each time. Cephalopods like octopuses and squid, however, always seemed a little too different, with their tentacle-like arms and the radically different organisation of the musculature. Not to mention that they evolved from mollusks (like snails) that lacked limbs altogether. Not so: a new study has found that the genes are conserved back as far as an evolutionary divergence that occurred over 500 million years ago. Notably, the hedgehog cell signalling pathway (and I would have put money on this gene, of any of them) controls both the number of fingers you make on your hand, and the number of suckers a cuttlefish has on its arm. Original study here (open access), with again a very excellent accessible digest, which I’m fast becoming impressed with eLife for.

A modified type of PET scanner has been invented which allows a whole body scan to be performed in an astonishing 20 seconds – with an ordinary PET scanner this would take more like twenty minutes. It’s also safer because it involves less exposure to radioactivity. The new scanner has been approved for use by the FDA and will have a whole range of applications, including making it much easier to move children (who find it difficult to stay still for long enough in a conventional scanner) and tracing drug flow throughout the body.

For UK readers: the government is opening a public consultation on whether they should fortify flour with folic acid. This is a vitamin we all need for general health, but it’s particularly important in the first three months of pregnancy, as a deficiency can lead to neural tube defects such as spina bifida. This is when the brain or spinal cord doesn’t fully close during development of the foetus. At the moment there is no food fortification; women are advised to take vitamin supplements in the first trimester of pregnancy but of course poorer women tend to miss out; and many women may not realise they’re pregnant until quite late. Personally I’m in favour of supplementation, as it would reduce significantly the incidence of these birth defects, and it’s very unlikely to have any harmful effects – it’s difficult to take this in excess. You can add your views here.

At least two hours a week spent in nature seems to be the minimal threshold for promoting general health and psychological wellbeing, and this seems to hold true across a variety of groups, including the elderly and those with long-term health issues. The benefit peaked at around 300 minutes a week. Interestingly, it doesn’t seem to matter what sort of “nature” it is – remote forest or urban park has the same effect – nor whether you had the exposure in one block or multiple short ones. This is very encouraging as it’s an achievable target for people, and inexpensive – but those who are most likely to lose out are those in poor urban environments and the time-poor, of course. Original study here (open access).

A short and sweet little video that’s about antlers – but also about the interesting links between switching on the annual and very rapid growth of these structures, regeneration, and the genes that are inappropriately switched on in the uncontrolled growth seen in cancers. The video doesn’t go into details, but there’s a perspective on the original research here, and the published article may be found here (paywalled).

And finally, remember the Horta from Star Trek, the silicon-based lifeform that made tunnels as it ate through rock (pictured)?

Kirk and the Horta, Star Trek, 1967 Paramount Pictures, via Wikipedia

Well, it turns out we have our own carbon-based lifeforms on earth that will happily eat rock. And I’m not talking a weird species of bacteria that uses minerals to generate energy, but a bona fide animal. It’s a shipworm (actually a type of clam). These more normally consume wood (hence their destruction of wooden ships) but this freshwater species from the Philippines eats rocks and craps sand. Wow. Original study here (open access).

I’m on holiday for a bit so Sunday Science will return in 3 weeks, not the usual two.

Featured image

Credit Oscar Tarazona and Martin Cohn/University of Florida via eLife.


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