In today's edition:
- Gene Variation May Raise Risk of H.I.V., Study Finds
- Counting monkeys tick off yet another 'human' ability
- Frozen embryos give bouncier babies
- Drought-resistant wheat beats Australian heat
- Making formula milk more like mum's
Gene Variation May Raise Risk of H.I.V., Study Finds
A genetic variation that once protected people in sub-Saharan Africa from a now extinct form of malaria may have left them somewhat more vulnerable to infection by H.I.V., the virus that causes AIDS. The gene could account for 11 percent of the H.I.V. infections in Africa, explaining why the disease is more common there than expected, researchers based in Texas and London say. The researchers said their finding had no immediate public health consequences. But if confirmed, it would offer an important insight into the biology of the virus.
The genetic variation has been studied in United States Air Force personnel, whose H.I.V. infections have been followed for 25 years. African-Americans who carried the variation were 50 percent more likely to acquire H.I.V. than African-Americans who did not, although their disease progressed more slowly, say researchers led by Sunil K. Ahuja, director of the Veterans Administration H.I.V./AIDS Center, San Antonio, and Matthew J. Dolan of the Uniformed Services University in Bethesda, Md. Their results were reported Wednesday in the journal Cell Host & Microbe.
The genetic variation, called a SNP, or snip, involves a change in one unit of DNA. This particular snip has a far-reaching consequence. It prevents red blood cells from inserting a certain protein on their surface. The protein is called a receptor because it receives signals from a hormone known as CCL5, which is part of the immune system’s regulatory system.
The receptor is also used by a malarial parasite called Plasmodium vivax to gain entry to the red blood cells it feeds on. About 10,000 years ago, people in Africa who possessed the SNP variation gained a powerful survival advantage from not being vulnerable to the ancestor of Plasmodium vivax. The SNP eventually swept through the population and the vivax parasite died out in Africa, to be replaced by its current successor, Plasmodium falciparum.
More than 90 percent of people in Africa now lack the receptor on their red blood cells, as do about 60 percent of African-Americans.
The possibility that the receptor has a bearing on H.I.V. infection first occurred to Robin Weiss, a biologist at University College, London, after he noticed that the virus seemed to be hitchhiking on red blood cells. Dr. Weiss, who wrote the new report with Dr. Ahuja and Dr. Dolan, showed in laboratory tests that H.I.V. latches onto the receptor in place of its intended guest, the CCL5 hormone.
The Texas-London research team is not certain how lack of the receptor promotes H.I.V. infection, but Dr. Ahuja said the red blood cells acted like a sponge for CCL5. Because CCL5 is known to obstruct multiplication of the virus, having lots of the hormone in the bloodstream may prevent infection. Conversely, people whose blood cannot soak up the hormone could be more vulnerable.
Dr. Weiss said the red blood cell receptor was similar to another receptor, CCR5, which occurs on the surface of the white blood cells that are H.I.V.’s major target. A small percentage of Europeans have a mutation that prevents the CCR5 receptor from being displayed on the surface of white blood cells, and they are protected against H.I.V.
It is somewhat puzzling that the absence of the two receptors has the opposite effect — vulnerability to H.I.V. when the red cell receptor is missing, protection from it when the white cell receptor is withdrawn. The researchers offer an explanation that they concede is far from straightforward.
Dr. Goldstein said that in parts of the United States, African-Americans have a higher infection rate than European-Americans, and that patients with a higher proportion of African genes may be more vulnerable to H.I.V. for reasons unconnected to the SNP. Nonetheless, the SNP would show up in a greater proportion of infected people simply because of their African heritage. If so, the gene’s apparent association with H.I.V. infection could be just coincidental, not causal.
The researchers took steps to rule out this possibility, but Dr. Goldstein said those steps might not have been adequate.
Although H.I.V. is too recent an infection to have left an evolutionary mark on the genome, human ancestors would have been exposed to malarial parasites and to S.I.V., which infects monkeys, and the genome still bears the marks of these challenges to survival. Better knowledge of these adaptations will help understand the biology of H.I.V. infection, he said. source
My comment: I find that article very intriguing and quite possible explanation. I don't see why the absence of a receptor in the red blood cells and the white blood cells lead to controversial results since those receptors are made from different hormones, obviously. Their connection may be uncertain, but that's all.
Counting monkeys tick off yet another 'human' ability
- 11:03 01 July 2008
- Ewen Callaway
At this rate a monkey might prove the Riemann hypothesis. Rhesus macaques have been shown to possess yet another numerical talent once thought unique to humans – they can simultaneously count audible beeps and dots on a computer screen.
Their ability to comprehend numbers not as just discrete images or sounds, but as abstract representations that can be combined suggests that such maths skills aren't unique to humans, says Kerry Jordan, a psychologist at Utah State University, Logan, US, who led the new study.
This sort of evidence "shows that [animals] have these precursors to math very early on in the evolutionary line and early on in development," she says.
Jordan and colleague Elizabeth Brannon, of Duke University in Durham, North Carolina, US, trained two eight-year-old female macaques to equate beeps to dots on a computer screen. So if a monkey heard seven beeps, it knew to tap a square on the screen displaying seven dots.
Next, the researchers tested the monkeys’ training in adding dots and beeps together.
The animals were presented dots of different sizes flash onto a screen. At the same time they heard a series of short tones.
To determine if the monkeys could combine the two, Jordan and Brannon showed the animals a screen with two numerical choices, represented as dots – one the correct sum, one incorrect.
Both monkeys did better than 50:50 – one added the sights and sounds correctly 72% of the time, the other 66% of the time.
Both monkeys tended to make mistakes when the right and wrong answers were numerically similar. For instance, if the choices were one and eight, the animals rarely got it wrong. But they found it harder to choose between, say, five and six.
People make the same kind of errors when making snap numerical judgements, such counting the number of people in a crowd, says Jordan, which is further evidence that our abstract maths skills aren't unique.
The monkey's ability to add numbers seen and heard together makes sense in the wild, says Jordan.
"If you have an animal trying to make a decision to defend its territory, it's going to want know how many other animals it has to deal with," she says. It would do this by combining information on how many animals it could see with how many it could hear.
Irene Pepperberg, a psychologist at Harvard University in Cambridge, Massachusetts, who trained a parrot named Alex to add small sums, says the paper confirms observations in the wild.
Flycatchers, for instance, seem to communicate their mood to other birds using a numerical combination of song and wing motions. The more wing flicks and songs, the more likely it is to attack another bird, she says.
My comment: A very interesting experiment I believe. I know how well animals can learn things, because I love dealing with animals myself. It's amazing how intelligent a goat can be-an animal that you don't expect to be very smart. But still, they never ceased to amaze me. I think the important message from this article is that humans are not that unique. We might be the masterpiece in the moment, but we are nothing but a product.
Frozen embryos give bouncier babies
- 09 July 2008
FROZEN embryos do better than fresh. That's the surprising conclusion of a study of children conceived by IVF which set out to address concerns that freezing might harm embryos.
Anja Pinborg of Copenhagen University Hospital in Denmark studied more than 1200 children born in the country between 1995 and 2006 as a result of IVF using frozen embryos and compared them with almost 18,000 children born after conventional IVF using fresh embryos.
The frozen embryos produced babies of roughly normal birth weight, while those from conventional IVF were on average about 200 grams lighter, Pinborg told the European Society of Human Reproduction and Embryology meeting in Barcelona, Spain, on 8 July.
Freezing an embryo shortly after fertilisation is unlikely to improve its viability, though. An alternative explanation, Pinborg argues, is that embryos able to survive the freezing and thawing process are likely to be healthier. "There's selection," she suggests.
What's more, women who have eggs frozen for later use tend to be younger and in better physical shape. And unlike women given conventional IVF, they will not be trying to establish a pregnancy immediately after being given hormone treatment to harvest their eggs - which it is thought could impair the process of implantation.
Pinborg's team also found that babies from frozen embryos were no more likely to suffer birth defects or neurological problems than conventional IVF babies.
My comment: That's a good news mainly for all the women that want to become mothers trough IVF. So it looks like freezing the embryos isn't such a trouble for them. Which is nice.
Drought-resistant wheat beats Australian heat
- 28 June 2008
WILL Australia's farmers fall for the charms of drought-resistant wheat, even if it's genetically modified? Faced with climate change and a growing food crisis, enthusiasts certainly hope such traits will help overcome aversion to GM technology.
Of 24 strains of GM wheat tested in field trials, two lines exceeded the yield of the non-GM variety by 20 per cent under drought conditions, according to German Spangenberg of the Victoria Department of Primary Industries in Melbourne, Australia. The results were presented last week at the Bio2008 convention in San Diego, California.
Environmental groups remain unconvinced. "The main driver of genetic engineering is to make it possible to patent crop strains. That won't help farmers in developing countries who need to keep back seeds for their next year's crop," says Louise Sales of Greenpeace Australia in Sydney.
Australian farmers may yet be persuaded. The forecast for this year's wheat crop has just been trimmed by 9 per cent because of dry conditions, although it may still be up by 10 million tonnes compared to last year's drought-devastated crop. source
Making formula milk more like mum's
- 14 July 2008
- Magazine issue 2664
Breast is best. There's no doubt about it. The list of proven benefits grows longer every year. Breastfed babies are not only protected against a huge range of infections, they also enjoy lifelong benefits, from higher intelligence to a lower risk of obesity and diabetes.
The reason, we are discovering, is that breast milk is the ultimate functional food. As well as providing babies with the essential nutrients they need to grow and develop, it also contains hundreds of active components that do everything from targeting dangerous pathogens and boosting the development of a baby's gut to preventing allergic reactions and increasing appetite. What's more, the composition of breast milk changes over time to match babies' needs - levels of natural painkillers called beta-endorphins are highest right after birth, for instance, while levels of most nutrients gradually fall over the first year or so.
Due to its benefits, health authorities recommend breastfeeding exclusively for the first six months of a baby’s life, followed by breastfeeding in addition to solid food until children are at least a year old. Yet in the Us, just 11 per cent of babies are exclusively breastfed up to the age of six months. In the UK, the figure is just 3 per cent.
Mimicking human breast milk is virtually impossible. Besides the fats, proteins, carbohydrates, minerals and vitamins that babies need to survive, breast milk also
includes hormones, immune signalling molecules, antibodies and even living immune cells. It also contains live bacteria that help colonise a baby’s gut, along with substances that promote the growth of beneficial gut bacteria, endocannabinoids that stimulate suckling and appetite, stem cells with unknown purpose.
What we do know is that breast milk helps protect babies against disease in numerous different ways. It contains hundreds of specific substances that provide general protection against infections, ranging from sugars that stop bacteria sticking to gut cells,and fats that disrupt certain kinds of viruses, to an array of signalling molecules that stimulate immune development.
It also includes tailor-made protection in the form of antibodies specific to viruses,
bacteria and toxins that the mother has already been exposed to. In breastfed babies, these antibodies help mop up pathogens and toxins in the mouth, throat and gut. the way in which they are produced is highly sophisticated: some milk antibodies are secreted by immune cells that have migrated from the mother’s gut to her breasts.
Breast milk also contains living immune cells from the mother, which have been shown to survive in the baby’s gut, where they may target pathogens directly. some even enter the infant’s body proper, and might help “educate” its immune system. a mother’s milk also appears to teach her infant’s immune system what not to attack: it contains potential allergens eaten or even breathed in by the mother, along with factors that tell the baby’s immune system not to overreact to them.
By contrast, most infant formulas are made from cow’s milk. This also contains active components, but many are specific to cows, the levels differ greatly from those in human milk.
Genetic engineers have taken the first steps towards manufacturing around a dozen protective proteins found in human milk. The two closest to commercialisation are lactoferrin and lysozyme, an enzyme that attacks the cell wall of some bacteria and is thought to act in synergy with lactoferrin.
Human lactoferrin and lysozyme produced in genetically modified rice have produced
positive results when added to oral rehydration solutions, which are the main treatment for diarrhoea in developing countries. source
My comment: Ok, two comments: first, obviously the breast milk is an absolute natural perfectness for feeding a growing person. And second: if you read in the article, you'll see that there is a survey on 140 that took the proteins lactoferrin and lysozyme and they had less diarrhoea than those taking standard solution with no adverse effects. However this is a very small number of people to conduct a research and also, the guy that made it, works for the company that produces it (and also GM modified rice). That's why I'm naturally suspicious toward such researches. You can't promote something on the base of internal company data. There should be an independent assesment. And that's what precisely the article is against which is disgusting.