the-BA : Science News Digest

Tasmanian Devil (Image copyright: istockphoto.com)

In the science news this week: a genetic link is found to the African HIV epidemic, evidence water was ‘widespread’ on early Mars, and infectious cancer alters the mating behaviour of Tasmanian Devils. Plus, grunting fish tell us about our ability to speak...

Scientists have discovered that a DNA variant that is found in 90 per cent of Africans but virtually unknown among other ethnic groups substantially increases the risk of HIV infection, reports the Times. Those with the genetic change, known as ‘Duffy-negative’, are 40 per cent more likely to contract the disease than those without it.

Professor Robin Weiss, a member of the study team from University College London, said: ‘It could certainly be a contributing factor to the scale of the epidemic in sub-Saharan Africa. It’s the first time, so far as we understand, that a genetic factor that increases susceptibility to infection has come into play.’

The reason that the Duffy-negative gene is spread so widely through the African population is likely to be because it provides resistance to a form of malaria. This would have been highly advantageous in evolutionary Africa, whereas HIV is a relatively new pathogen.

‘After thousands of years of adaptation, this Duffy varieant rose to high frequency because it helped protect against malaria,’ said Matthew Dolan of the San Antonio Military Medical Centre in Texas. ‘Now, with another global pandemic on the scene, this same variant renders people more susceptible to HIV. It shows the complex interplay between historically important diseases and susceptibility in comtemporary times.’
--------------------

The Guardian reports on how a good night’s sleep has been shown to promote learning.

By scanning the brains of volunteers, a team at the University of Geneva found that sleep causes weak memories to become strong by stimulating new brain connections.

For the study, volunteers were given specific tasks to perform – either to remember unknown faces or to follow a moving dot on a computer screen with a joystick. Some were then allowed to sleep while others were not, and asked to repeat the tasks the next day while their brain was scanned.

According to Dr Sophie Schwartz, a scientist on the team, the results showed ‘a period of sleep following a new experience can consolidate and improve subsequent effects of learning from the experience’.
--------------------

Plans for the first mission to bring back samples of rock and possibly life from Mars have been revealed.

The mission is seen as the next big step before a possible crewed mission to Mars, reports the Guardian, and has been proposed for launch between 2018 and 2023. Although there have been seven successful landings on Mars, this would be the first time that samples were returned from the Red Planet to Earth.

The mission could cost up to $8 billion and would need funding and expertise from NASA, the European Space Agency, and other national space agencies.

Its enormous cost is not the only hurdle the mission faces. According to Professor Colin Pillinger of the Open University, ensuring that the samples brought back do not contaminate our planet may prove very difficult. However, he does not doubt the importance of the mission: ‘Everybody knows this is what you have got to do if you want to really get to the bottom of Mars.’
--------------------

In other Mars-related news, BBC News reports that according to new findings water was once widespread on the Red Planet.

The revelation comes from data provided by an instrument known as CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) on Nasa’s Mars Reconnaissance Orbiter Spacecraft. By analysing over 500 colours present in reflected sunlight, CRISM is able to detect particular minerals on the Martian surface.

The work revealed that clay minerals, which can only form in the presence of water, are present across vast regions of the planet’s surface. Situated within the ancient highlands that cover over half of Mars, the clay-rich regions were buried by lava flows during later, drier periods in the planet’s history. However, subsequent impact craters at thousands of locations have exposed them again.

‘The big surprise from these new results is how pervasive ad long-lasting Mars’ water was, and how diverse the wet environments were,’ said Scott Murchie, CRISM’s Chief Scientist.
--------------------

Meanwhile, the High-Resolution Stereo Camera aboard the European Space Agency’s Mars Express probe has beamed to Earth some of the clearest pictures ever taken of Mars’ surface.

They show steep-sided valleys and deep canyons suggestive of water channels, as well as two five-mile wide impact craters, and a 15-mile long magma dyke that provides evidence of volcanic activity.
(See the striking images at the Telegraph)
--------------------

The Telegraph also reports this week on how schizophrenia is more to do with a split protein than a split personality.

Scientists from the Flanders Institute for Biotechnology, VIB, and Catholic University of Leuven have discovered that the disease develops due to faulty snipping of a protein called neuregulin. A pair of ‘molecular scissors’ known as Aph1B/C-gamma-secretase usually snips the protein to the correct length, but this can sometimes be disturbed. Laboratory animals in which neuregulin was not snipped successfully showed symptoms very similar to those of schizophrenia.

Scientists hope the discovery could lead to new treatments for schizophrenia, one of which could be drugs that act like the molecular scissors. However, research is still at a very early stage, and there will be no immediate benefit for the one in 100 people who suffer from schizophrenia.
--------------------

The Guardian reports that the first floating wind turbine will go to sea at the end of the month. The prototype, built by British company Blue H, will float 12 miles off the coast of Southern Italy, and could prove to be the future of offshore energy production.

Its makers believe that the floating device, which will be anchored by weights on the seabed, will have many benefits over existing offshore turbines. One of these will be the cost of installation, as there will be no need for fixed foundations. They also believe that floating wind turbines will have less impact on shipping, military radar and coastal seabird populations.

In the future, Blue H hopes to float full scale wind farms far out in the deep ocean, where they would be invisible from the coast and could benefit from stronger winds. Electricity could then be sent back to shore by underwater cables.
--------------------

A study of a remote Amazonian tribe with no concept of numbers and counting has questioned the belief that humans have an innate mathematical ability, according to the Telegraph.

Members of the Pirahã tribe of northwest Brazil have a numerical ability similar to that of infants or some animals. Their language, which has only 300 speakers, doesn’t contain any words for specific numbers such as ‘one’ or ‘two’.

The US researchers who published the research in the journal Cognition believe that the tribe’s only way of expressing quantity is by use of words similar to ‘some’ and ‘more’.

Professor Daniel Everett who was involved in the work, spent much of his time between 1977 and 2007 living with the tribe. A previous study that he published suggested that the tribe did have words to express ‘one’ and ‘two’. However, the new research, which asked the tribe members to count down from 10 objects, revealed they used the word previously thought to mean ‘two’ when as many as five or six objects were present, and the word for ‘one’ for any quantity between one and four.

Edward Gibson, Professor of brain and cognitive sciences at Massuchusetts Institute of Technology, who led the research, said it was the first time this type of counting strategy had ever been observed but that it could also exist where other languages were thought to have ‘one’, ‘two’ and ‘many’ counting words.
--------------------

Tasmanian Devils, who face extinction in the wild due to Devil facial tumour disease (DFTD), have responded to their predicament with an abrupt change in breeding habits.

The animals are now mating at an unusually young age, reports BBC News. And, whereas before the emergence of the disease females typically began breeding around the age of two and continued to have annual litters until dying in their fifth or sixth year, they now often only have one litter.

DFTD, which is consistently fatal, is an infectious cancer. The tumours primarily affect adult Devils aged two or over, and death follows within five months. Tumour cells are spread directly by the animals biting each other – something that occurs between adult males and females in the mating season.

The Australian researchers who made the observations believe it is the first known case of an infectious disease leading to increased early reproduction in a species of mammal.

‘Devils have shown their capacity to respond to this disease-induced increased adult mortality with a 16-fold increase in the proportion of individuals exhibiting precocious sexual mortality,’ they reported in the Proceedings of the National Academy of Sciences.
--------------------

And finally…

Grunting, humming fish may hold clues to the origins of vocal sounds, scientists have discovered. The area of the fish’s brain that drives vocalisation was found to be extremely primitive, suggesting the ability to vocalise emerged very early in the evolution of vertebrates.

Toadfish and midshipman fish, nocturnal fish that live along the north-west coast of the US and Canada, emit a deep hum to lure females to a male’s nest, while a sharp grunt is used to scare off rivals.

A team from Cornell University looked at the area of the brain responsible for controlling call pitch and duration. They found that the neural networks responsible for this vocal patterning in fish was situated in the same region in frogs, birds and primates. The researchers then compared the evolutionary ‘family tree’ for vertebrates. The evolution of the fish could be traced back further than amphibians, birds and primates.

’You could see that [it] was a very ancient part of the nervous system shared by all vertebrates,’ said Professor Andrew Bass, lead author of the paper in Science. ‘We came to the conclusion that it must have evolved early in time before these different groups emerged from the evolutionary family tree – around the time when bony fishes evolved about 400 million years ago.’
(BBC News)