Monday Science: Brains and Blue Icing

It is said that when a sense is lost, particularly that of sight, remaining senses are heightened. This is true not only in those individuals who could once see — although they do have better spatial awareness — but also in people who were born blind, since these individuals have been shown to have accelerated brain processing ability in the regions responsible for the remaining senses. But how can the brain do this? How can it intrinsically know things it can no longer directly determine in the ways it was built to do?

Fruit flies similarly have the ability to continue to perceive their environment in times of sensory loss. For example, they can determine the nutritional value of food, even when their ability to taste has been impaired. Now, a study in Nature Neuroscience has uncovered details as to how this might be possible.

Flies that are incapable of tasting — by means of genetic mutation in the taste receptors around its mouth and proboscis — actively select easily digested sugars over harder to stomach compounds. After all, they still need to eat well. This ability is particularly strong during times of starvation, so the researchers looked deeper to see if this was to do with sugar levels in the haemolymph, the liquid that circulates around the insects’ body, something akin to blood plasma. They found that starved flies were no longer able to choose between glucose and agar, or different kinds of glucose, if their food was supplemented with a chemical that prevents the passing of glucose from the gut to the haemolymph. Just to check that this wasn’t because the chemical was messing everything up and the flies were just off their food completely (and who can blame them, on a diet of agar and chemicals), they repeated the experiment using agar and fructose, which differs chemically and isn’t prevented from passing into the haemolymph. This time the flies chose the fructose.

On top of this, flies that have had their ability to taste restored, but are still chemically unable to absorb glucose into their haemolymph, actively choose the sweetest foods they can find, even if those sugars are the hardest to digest and therefore the worst nutritional option. They’re like toddlers presented with the option of cake with blue icing, or Ryvita and hummus - sweetest wins, regardless of whether it's any good for them.

If they can taste, but not absorb sugar into the blood, flies make bad food decisions. If they can't taste, and can't absorb sugar into the blood, flies can't decide anything, and eat whatever they can find. Clearly, there’s something about the presence of glucose in the haemolymph that activates a taste-independent pathway that selects nutritional food.

To try to work out the molecular causes of this, the researchers looked for mutations in genes that caused normal, happy healthy flies to suddenly lose the ability to distinguish different sugars. They found one and, obviously, named the gene it was in ‘cupcake’. Cupcake is similar to a human gene called, boringly, SGLT1, which is responsible for the absorption of glucose into the blood from the small intestine. So is cupcake responsible for glucose movement into the haemolymph, and therefore subsequent food selection based on nutritional value?

The answer, confusingly, is no.

The curiously beautiful fruit fly
ellipsoid body (right)
Source

Oddly, cupcake isn’t used in the gut or the blood vessels. It’s only expressed in a highly specific set of nerves in the fly brain, right in the middle of it, in a circular structure called the ellipsoid body. The ellipsoid body is part of the brain responsible for movement, although it is part of a larger structure called the central complex, which is more widely responsible for behaviour and, neatly, processing of the senses. Restoration of cupcake gene activity in these nerves returned the ability to make good food choices in mutant flies.

Deep in the fly brain, a tiny bundle of cupcake nerves somehow fire electrical impulses when, after hours of starvation, sugar reaches the gut and passes into the haemolymph. This then changes the fly's behaviour to seek out more of the good quality food that has triggered this reaction. Whether the sugar directly triggers the nerves or other, indirect processes are at play remains to be seen.

All of this makes me wonder — what processes, decisions and impulses are going on in our brains, independently of the information we feed them? Could we make good food choices even without the ability to taste? If people can achieve spatial awareness without the ability to see, perhaps this is not so far fetched. Brains are the most remarkable of things.


Dus, M., Ai, M. & Suh, G. S. Taste-independent nutrient selection is mediated by a brain-specific Na(+)/solute co-transporter in Drosophila. Nature Neuroscience 16, 526-528 (2013)
doi:10.1038/nn.3372

Monday Science: The Happy Birthday DNA Show

TWO weeks ago I attended the Communicating Your Science workshop organised by the Genetics Society and held at Chicheley Hall, a country mansion owned by the Royal Society. The workshop focused on storytelling, communication in interdisciplinary research, scientific writing, publishing, business and radio broadcasting. I absolutely loved it. As part of this, we were challenged by The Naked Scientists crew to create a 15 minute radio show, with less than 24 hours notice, to be recorded as live with no interruptions. Above is a link to the show my group created, which just so happened to be recorded on 25th April 2013, the 60th anniversary of the Watson and Crick paper in which the structure of DNA was revealed. We were allowed some pre-recorded segments, which is where I feature along with our vox pops from 'the streets of Milton Keynes' (actually the staff in the venue, hence the tweeting birds in the background). Consequently I had no live vocals so I took on the role of show producer, gesticulating silently to signify timings, panic and relief when it was all over!

Disclaimer: as this was done so quickly, the science in it may not be completely accurate. It was more for the experience of putting a show together than for complete accuracy.

The Universe As It Is

“Peeping through my keyhole I see within the range of only about thirty percent of the light that comes from the sun; the rest is infrared and some little ultraviolet, perfectly apparent to many animals, but invisible to me. A nightmare network of ganglia, charged and firing without my knowledge, cuts and splices what I do see, editing it for my brain. Donald E. Carr points out that the sense impressions of one-celled animals are not edited for the brain: ‘This is philosophically interesting in a rather mournful way, since it means that only the simplest animals perceive the universe as it is.’”

Pilgrim at Tinker Creek by Annie Dillard
(with thanks to Liz Wainwright)

#bgrs2013

Click here to read the Storify of the event.
(Biosciences Graduate Research Committee student symposium 2013, University of Birmingham)

RiAus: Drugs in Sport

MY latest RiAus blog post is a review of one of their events, called Science Behind the Headlines: Drugs in Sport, and you can read it here. You may think it odd that I am reviewing an event held in the Science Exchange, Adelaide, when I live in Birmingham, UK. The problems this geographic discrepancy present are addressed in my review, as are the perils of being a fan of tea. Further details about the event can be read here. 

My article:

Review of Science Behind the Headlines: Drugs in Sport by Simon Bishop for RiAus.

RiAus: Defying the laws of nature. Again.

EXCITING news! I am now a blogger for the Royal Institution of Australia (RiAus). My first post, 'Defying the laws of nature. Again.' is now up, and can be accessed here. As it was my first post, I couldn't resist the temptation to bring in a few old friends: the thylacine and the Tasmanian devil. I am looking forward to the many future opportunities this position with RiAus will offer, and the challenges they set me!

Defying the Laws of Nature. Again. by Simon Bishop for RiAus

Monday Science: Look at his happy, happy face

IN THE beginning, there was the mouse. There was also the nematode worm (Caenorhabditis elegans), the African clawed frog (Xenopus laevis), the fruit fly (Drosophila melanogaster), thale cress (Arabidopsis thaliana) and the zebrafish (Danio rerio), and, to a lesser extent, chickens, rabbits, guinea pigs and daphnia. These were the model organisms of science. Now, it seems, there's a new member of the club.

Say hello to this chap:

Source

Doesn't he look happy? He's an axolotl, a curious species of endangered amphibian that lives only in the lakes around Mexico City — lakes that are being threatened by pollution and competition by invasive species. Fully grown axolotls are neotenic salamanders, 'adults' that are stuck with juvenile features because they never went through metamorphosis. Other species of salamander lose their gills and move on to land as they develop, and the happy-go-lucky, flapping external gill form of the axolotl can be induced to do this by the artificial application of thyroid stimulating hormone, but in its natural environment the axolotl is content to stay in a larval state for the duration of its life. Think of it as a tadpole that has grown its legs, but never becomes a frog.

Axolotls are not a new model in science, but a recent push into research in regeneration and injury repair has seen a flurry of articles and interest in using the threatened amphibian. Because of its perpetual larval state, the axolotl is able to regenerate lost limbs, instead of forming a scar. February was a bumper month for axolotl developmental biology papers, so I picked one, and now I’m going to tell you what it said.

Exciting Tasmanian Devil News!

REGULAR readers of this blog will know that I am a big fan of the Tasmanian Devil. It is a black and white ball of fur, underneath which is a marsupial carnivore, one so keen on its food that once it starts eating nothing can distract it, and nothing will be left once it is finished (its blood-curdling squeals of delight are the origin of its name 'devil', when heard by early settlers at night). It is also dying.

This from a previous post of mine:

In a phenomenon almost unique to science, the already small population is suffering from a transmissible form of cancer called Devil Facial Tumour Disease (DFTD), with over 70% of the population infected. It is almost completely lethal, causing swelling in the mouth and face, leading to suffocation and starvation. 80% of the population has been wiped out since its discovery in 1996, and it is predicted that the species could be extinct within 25-35 years.

I have previously covered the discovery that the low genetic diversity in the species has existed in the population for at least 100 years and how this has implications on how we decide which species to invest conservation efforts on. I also introduced the disease and explained why low genetic diversity in the species could be a blessing or disaster for its survival, and how, biologically speaking, the cancer is utterly remarkable — it is contagious and makes its own myelin, a protein usually seen only in the nervous system, which the immune system never attacks.

I hurry through these details because there is new news. It is covered very nicely here and here by Ed Yong, but I shall cut to the chase: