Welcome to this week’s Sunday Science, featuring the great white shark genome, youthful female brains, 3D printing drugs on demand, why broken sleep leads to strokes, the neuroscience behind a popular treatment for PTSD, and more…

The genome of the great white shark has been decoded, with some fascinating insights, for example into their superior wound healing abilities, and that their much-vaunted sense of smell seems to be down to a completely different genes than those well-known in other species. Even more intriguingly, they have a large number of genes involved in “genome stability” – these have protective effects against the type of DNA damage that leads to cancer, for example by repairing DNA damage. There’s a huge amount of research in this area in humans, primarily with the aim of tackling cancer, so these could yield some really interesting avenues of research. In the sharks, they appear to be present because their genome has large numbers of “jumping genes” which can insert randomly in the DNA and cause mutations, which is another puzzle in itself. Original article here (paywalled).

There has been a catastrophic decline in global insect populations, a comprehensive study has found, with 40% of known insect species declining and a third now endangered. This threatens global ecosystems and our own food security. The main cause seems to be intensive agriculture, but increased urbanisation and climate change are also playing important roles. Original journal article here.

A somewhat intriguing result here: human female brains appear to be, in terms of brain metabolism as opposed to actual age, a few years younger than male brains. It’s unclear as to why, but it may make women more resistant to age-related cognitive decline than men. The authors point out that other research positing sex differences between male and female brains are chronologically age-matched – which might not be an accurate comparison. I have some issues with the way they’ve extrapolated “metabolism” from PET scans giving proxy indications of glycolysis, but it’s nevertheless an interesting study and worth exploring further.

The devastating rabbit disease myxomatosis was introduced in Australia in the 1950s to control the exploding rabbit population there, but also spread to the UK and France. It causes blindness and death in rabbits, and initially killed 99% of infected animals, an astonishingly high death rate for any infection. I remember occasionally seeing blind rabbits in the road as a child in the 1980s. Of course, under such selective pressure, the rabbits started evolving resistance. A fascinating paper in Science describes how (paywalled) but there’s a much more accessible feature from Cambridge University here.

Not enough sleep or disrupted sleep is bad for you, as most people would agree with. One of the ways it is bad for you is increasing your risk of heart attacks and sleep. A study in mice looking at how this happened, identified that long-term disrupted sleep reduces the levels of the protein hypocretin, which is produced in the brain’s hypothalamus. Lower levels of this protein, which has been linked to sleep disorders such as narcolepsy, leads to an over-production of white blood cells that migrate to the arterial walls. Here, they promote atherosclerosis, or “hardening” of the arteries. Original study here. (For the non-specialist, there’s a Science Daily article here).

EMDR, or Eye Movement Desensitisation and Reprogramming, is a method of treating post-traumatic stress disorder (PTSD). In PTSD, stressors can become bound up in the memory with specific environmental stimuli to an intense degree, triggering anxiety. Much therapy for PTSD involves going through trauma reminders in safety (e.g. in therapy) produces a different type of “extinction” memory that reduces anxiety – but this doesn’t always work, or work for that long. In EMDR, the patient recalls the trauma whilst being shown visual stimuli designed to stimulate repetitive eye movements. There are some conflicting data over how well it works, but the main mystery has been why it works at all. Now, a clever new study has revealed that the neural pathways in the brain engaged by the rapid eye movement compete and favour extinction memories over another set of brain pathways that favour the persistence of fear. A more technical precis of the paper is here, the original study is here (paywalled).

A nice video here featuring some Sussex University research into the 3D printing of drugs on demand.


Featured image

Great white shark (Carcharodon carcharias), off the coast of South Africa. Wikipedia Hermanus Backpackers [CC BY 2.0 (https://creativecommons.org/licenses/by/2.0)%5D




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