Marching On

So you’re a woman out for a night on the town, but the men just won’t leave you alone. How can you get a meal without being hit on? Easy; just put yourself close to someone better looking, and rely on the shallowness, and hornieness, that has been making life difficult for you up ’til now.

Not a new strategy to be sure. Indeed as revealed in one of the stories I wish I wrote, Trinidadian guppies are way ahead of you. The research is covered in the March edition of Australasian Science, even though the researchers are from Exeter and Copenhagen.

Basically, male guppies are pesky bastards, and while the females are only fertile a few days a month, the males aren’t terribly choosy. But the fact that they will chase anything in the guppy equivalent of a skirt doesn’t mean the males can’t tell the difference – given the choice between a receptive female and one who isn’t they’ll take the one who is ready to breed.

Exeter’s Dr Safi Darden notes, “It is now becoming apparent that males of some species choose to associate with relatively less attractive males to increase their chance of mating. We wanted to see if females also chose their same-sex companions based on attractiveness, but in this case, to reduce unwanted attention.” It turns out the answer is yes. When offered a choice of spending time in with a receptive female, or one that was not, unreceptive female guppies preferred to hang around the one who was ready to mate, and were rewarded with less male harrassment. They confirmed the experiment using water in which receptive females had swum, which also proved attractive, suggesting the females are picking up on the same pheromones that are leading the males to know which females are fertile.

Not having written the article myself, I was not in a position to raise the possibility with the researchers that in fact the “non-receptive” females actually bat for the other side, and are drawn more by the attraction of an attractive member of their own sex than the desire to avoid the blokes.

As is becoming a theme in this blog, I think people are far too eager to jump to conclusions about human sexuality based on what is observed in particular animal species. These are fish we’re talking about for Darwin’s sake. But that doesn’t stop me fining it amusing.

I have to admit it’s not a strong edition when it comes to Browse articles, but I think two are worthy of mentioning. Researchers at the University of Sydney think they have a double breakthrough in the battle against dementia. Now let me say that I am a little skeptical about this claim. Skeptical in the true meaning of the word, not cynical or disbelieving.

What they have done is produce a mouse that has a disease they think is a model for both Alzheimer’s and frontal temporal dementia, the second most common form of early onset dementia (and yes even as someone who supports the use of animals in medical research, I’ve got a few qualms here). And then they have produced a vaccine that doesn’t just stop the progress of the disease, it actually reverses it. If they’re right that this really is a good model for the human conditions this is truly huge. Something that can reverse, at least partially, Alzheimer’s with frontal temporal dementia thrown in? You could start booking your flight to Sweden. But animal models are often overfitted to humans. Without knowing a lot about the field I didn’t find the explanation of why a single disease in mice is a model for two distinct human diseases entirely convincing.

Nevertheless, there is reason to think that these guys are onto something that might prove useful. In a nutshell, they chose to target the neglected aspect of Alzheimer’s, the presence of insoluble tau proteins thought to cause the creation of neurofibrillary tangles. For obvious reasons Alzheimer’s research is huge these days, but most of it focuses on beta amaloid plaques, the other really obvious feature when it comes to dissecting the brain of those who have suffered from it. Lars Ittner believes that this is because the plaques, lying outside the cell, are easier to get to than the bundles of tau proteins, which require one to get inside the cell. Consequently they should be easier to treat. Unfortunately, Ittner believes the plaques are not actually a very important part of the disease. He acknowledges they are something you don’t really want on your brain, but to Ittner it is the tau protein and associated tangles that are the key, the plaques are a minor downstream effect. If he’s right, neuroscientists have been like the drunk looking for his keys under the lamppost because the light is better there, even though it is not where he lost them.

The idea has been taken a step further in research that will be covered in the April edition, with evidence (published in Nature Neuroscience) that the problem is not the formation of insoluble tau, but that the tau that appears in this way was previously in soluble form, and is not replaced. The argument is that soluble tau has an important job to do, and when something causes it to start precipitating it loses the capacity to do it. (I’ve given enough away in advance, so I’ll keep you in suspense on what the Mental Health Institute think they’ve found is tau’s job.

The other Browse worth mentioning is on a study from the Journal of Neuroscience suggesting that rats that get plenty of love from their mothers are immune to opiate addiction. This is the sort of animal research that sounds like it involves a lot less suffering. On the other hand, even the researchers admit the results should not be applied too simplistically to humans. We certainly don’t want to add to the burden of mothers whose children like the needle a little too much.

Nevertheless, Adelaide’s Dr Mark Hutchinson used a well established technique to induce extra rat nurturing, which in turn produces extra doses of the immune system molecule interleukin-10 (IL-10).

“The more IL-10 produced in the brain, the less likely morphine causes an increase in craving or relapse weeks after initially being exposed to the drug,” Hutchinson told me. Rats that had been through the added nurturing process produce four times as much IL-10 as adults as those that got normal parental care (for a rat).

Hutchinson says that in humans about 60% of addictive response is genetic, and parental care is probably not the entire rest of the story. Nevertheless, he believes his finding is significant because for the first time it links in the brain’s immune response as important for addiction, rather than attributing a predisposition to neuronal wiring alone, as most people have thought.

Just to show it’s not all medical research this month, I’ve also got a Browse on the longest stellar jet ever observed (coming from a star in the Large Magellanic cloud, which appears to be over-represented in Really Big Things for such a small galaxy, a bit like the coastal highway from Newcastle to Cairns). And we now have a much more accurate map of how Antarctica looks under the ice, which should prove useful in working out how quickly glaciers will flow to the sea as the planet warms up.

I also have a feature (sub only), which started as a Cool Scientist column, on Dr Gavin Prideaux, who has been spending time deep beneath the Nullabor in an extraordinary cave system studying the exceptionally intact fossils of some of the animals that died there. If extinct giant kangaroos, three tonne wombats, desperately misnamed Tasmanian tigers and devils do it for you, take a look. If not, well I reckon it is still worth it for the photograph of Gavin digging out a bone beneath a truly extraordinary set of stalactites.

There’s some unexpectedly cheerful news on climate change amongst the other features (all also subscriber only), with signs some plants can adapt to the drying out of grasslands we can expect. This however is immediately canceled out by the following article on the havoc we are about to wreck on clown fish, amongst other reef species, through ocean acidification – another effect of too much carbon dioxide in the atmosphere. There is also an article on how cuckoos fool other birds into raising their young for them, which I haven’t read but looks interesting, and one on how smell and taste disorders in children may be a lot more damaging for their health than has been recognised.

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About Stephen Luntz

I am a science journalist, specialising in Australian and New Zealand research across all fields of science. My book, Forensics, Fossils and Fruitbats: A Field Guide to Australian Scientists is out now through CSIRO Publishing. I am also a professional returning officer for non-government organisations. I'm very politically active, but generally try to restrict this blog to scientific matters.
This entry was posted in Australasian Science, Behavioural Zoology, neuroscience, Paleontology, Uncategorized. Bookmark the permalink.

3 Responses to Marching On

  1. In Alzheimer’s research there has been long rivalry between those espousing the role of beta-amyloid plaques (the BAPtists) and those who favour tau (the TAUists). See, even medical researchers have a sense of humour (albeit somewhat lame). Right, I’m off to hang out with some guppies.

  2. That’s great Kim. Wish I had know that before my two articles on tau. I’ll try to remember it for when I get a story again, which no doubt I will.

  3. Pingback: Altheimer’s Update | Forensics, Fossils and Fruitbats

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