88 posts tagged genetics
The Game Theory of Life
-Applying game theory to the behavior of genes provides a new view of natural selection.
In what appears to be the first study of its kind, computer scientists report that an algorithm discovered more than 50 years ago in game theory and now widely used in machine learning is mathematically identical to the equations used to describe the distribution of genes within a population of organisms. Researchers may be able to use the algorithm, which is surprisingly simple and powerful, to better understand how natural selection works and how populations maintain their genetic diversity. By viewing evolution as a repeated game, in which individual players, in this case genes, try to find a strategy that creates the fittest population, researchers found that evolution values both diversity and fitness. Some biologists say that the findings are too new and theoretical to be of use; researchers don’t yet know how to test the ideas in living organisms. Others say the surprising connection, published Monday in the advance online version of the Proceedings of the National Academy of Sciences, may help scientists understand a puzzling feature of natural selection: The fittest organisms don’t always wipe out their weaker competition. Indeed, as evidenced by the menagerie of life on Earth, genetic diversity reigns.
“It’s a very different way to look at selection,” said Stephen Stearns, an evolutionary biologist at Yale University who was not involved in the study. “I always find radically different ways of looking at a problem interesting.” (via Game Theory Makes New Predictions for Evolution | Simons Foundation)
Genetic anomaly which switches on blonde hair is not linked to any other traits, scientists conclude
The fair-haired have long endured accusations that they are less intelligent than brunettes, to the extent that an unexpected show of stupidity is now referred to as a “blonde moment”. But blondes should take heart. Scientists have discovered that hair colour is determined by a single letter of the genetic code – and it is completely unrelated to any other inherited trait. It means that being blonde has no link to either intelligence or being gregarious. So if blondes really do have more fun, or come across as ditzy, the driving force is likely to be nurture not nature. Scientists at Stanford University found that switching a single letter of DNA can turn brunettes to blondes. “The genetic mechanism that controls blond hair doesn’t alter the biology of any other part of the body,” said lead researcher Professor David Kingsley. “It’s clear that this hair colour change is occurring through a regulatory mechanism that operates only in the hair. “The change that causes blond hair is, literally, only skin deep “We’ve been trying to track down the genetic and molecular basis of naturally occurring traits, such as hair and skin pigmentation, to get insight into the general principles by which traits evolve.” The gene switch which turns on blonde hair also played no part in eye colour, the scientists found, suggesting that blue eyes and fair hair are not genetically linked. “This particular genetic variation in humans is associated with blonde hair, but it isn’t associated with eye colour or other pigmentation traits,” Prof Kingsley added.
Tigers need diverse gene pool to survive
Stanford University Original Study
New research shows that increasing genetic diversity among the 3,000 or so tigers left on the planet, though interbreeding and other methods, may be the key to their survival as a species. Iconic symbols of power and beauty, wild tigers may roam only in stories someday soon. Their historical range has been reduced by more than 90 percent. But conservation plans that focus only on increasing numbers and preserving distinct subspecies ignore genetic diversity, according to the study. In fact, following that approach, the tiger could vanish entirely. “Numbers don’t tell the entire story,” says Elizabeth Hadly, professor in environmental biology at Stanford University and senior fellow at the Stanford Woods Institute for the Environment. She is a coauthor of the study, which appears in the Journal of Heredity.
That research shows that the more gene flow there is among tiger populations, the more genetic diversity is maintained and the higher the chances of species survival become. In fact, it might be possible to maintain tiger populations that preserve about 90 percent of genetic diversity. (via Tigers need diverse gene pool to survive | Futurity)
From genetic and genomic testing to new techniques in human assisted reproduction, various technologies are providing parents with more of a say about the children they have and “stirring the pot of ‘designer baby’ concerns,” writes Thomas H. Murray, President Emeritus of The Hastings Center, in a commentary in Science. Murray calls for a national conversation about how much discretion would-be parents should have. “Preventing a lethal disease is one thing; choosing the traits we desire is quite another,” he writes. He discusses public hearings two weeks ago by the United States Food and Drug Administration to consider whether to permit human testing of a new method of assisted reproduction – mitochondrial manipulation – that would prevent the transmission of certain rare diseases and perhaps address some causes of female infertility. At issue is the safety of the technology, as well as its ethical implications. Mitochondrial manipulation creates an embryo with the nuclear DNA from the prospective mother and father (which contains most of the genetic material) and the mitochondrial DNA (containing 37 genes) from a donor without mitochondrial defects. Among the ethical concerns is that daughters produced by this procedure could pass down the mitochondrial DNA to their children. “Up to now, the United States has not allowed such genetic changes across generations,” Murray writes.
Genes predispose obesity but it’s fullness that makes you fat
A genetic predisposition to weight gain and obesity in later life can in part be explained by a lack of feeling full after eating, according to a new study in JAMA Paediatrics. Although there has been some study of why some people appear more likely to gain weight, researchers from UCL and King’s College London were interested in how 28 of the 34 identified “obesity genes” affected children. They found that although someone might be predisposed to becoming obese, it was also due to a tendency to eat more. In other words, predisposition doesn’t mean growing large is inevitable, and recognising it may help avoid overeating. “Our findings suggest that satiety responsiveness [how full we feel after eating] is one of the mechanisms through which obesity genes influence weight,” Clare Llewellyn, research associate in the Health Behaviour Research Centre at UCL and a co-author of the study said. “Obesity genes influence satiety responsiveness, and through influencing satiety responsiveness, they indirectly influence your weight … This study indicated that the reason why some people feel full and other don’t is due to differences in our genes.” The paper is based on the participants to the Twins Early Development Study – a long-term study into more than 16,000 pairs of twins born in the UK between 1994 and 1996. But rather than compare siblings, the researchers chose to study 2,258 participants who weren’t related. The average age of participants was nine. And they used a polygenic (multiple genes) risk score (PRS), which adds up the number of genetic variants someone has that puts them at increased risk of obesity. (via Genes predispose obesity but it’s fullness that makes you fat)
For the first time, scientists at King’s College London have identified a gene linking the thickness of the grey matter in the brain to intelligence. The study is published today in Molecular Psychiatry and may help scientists understand biological mechanisms behind some forms of intellectual impairment. The researchers looked at the cerebral cortex, the outermost layer of the human brain. It is known as ‘grey matter’ and plays a key role in memory, attention, perceptual awareness, thought, language and consciousness. Previous studies have shown that the thickness of the cerebral cortex, or ‘cortical thickness’, closely correlates with intellectual ability, however no genes had yet been identified. An international team of scientists, led by King’s, analysed DNA samples and MRI scans from 1,583 healthy 14 year old teenagers, part of the IMAGEN cohort. The teenagers also underwent a series of tests to determine their verbal and non-verbal intelligence. Dr Sylvane Desrivières, from the MRC Social, Genetic and Developmental Psychiatry Centre at King’s College London’s Institute of Psychiatry and lead author of the study, said: “We wanted to find out how structural differences in the brain relate to differences in intellectual ability. The genetic variation we identified is linked to synaptic plasticity – how neurons communicate. This may help us understand what happens at a neuronal level in certain forms of intellectual impairments, where the ability of the neurons to communicate effectively is somehow compromised.” She adds: “It’s important to point out that intelligence is influenced by many genetic and environmental factors. The gene we identified only explains a tiny proportion of the differences in intellectual ability, so it’s by no means a ‘gene for intelligence’.”
World’s first green piglets born in China, sheep next
In Guangdong Province in Southern China, ten transgenic piglets have been born this year, in and under a black light, they glow a greenish tint. A technique developed by reproductive scientists from the University of Hawai`i at Mānoa’s John A. Burns School of Medicine was used to quadruple the success rate at which plasmids carrying a fluorescent protein from jellyfish DNA were transferred into the embryo of the pig. The green color is a marker that indicates that the fluorescent genetic material injected into the pig embryos has been incorporated into the animal’s natural make-up. The ultimate goal is to introduce beneficial genes into larger animals to create less costly and more efficient medicines. The IBR technique involves proprietary pmgenie-3 plasmids conferring active integration during cytoplasmic injection. This technique was also used to produce the world’s first “glowing green rabbits” in Turkey earlier this year. Turkey is expected to announce results of similar research involving sheep in the New Year. In the video below, the pigs — not unlike human children afraid of the dark — begin to squeal when the lights are turned off, except for the black light, which helps illuminate the green tint. The noise is because the scientists are holding the by-now-large piglets in a container to prevent their movement, to make the florescent glow most visible. (via World’s first green piglets born in China, sheep next | KurzweilAI)
Diabetes risk gene ‘from Neanderthals’
A gene variant that seems to increase the risk of diabetes in Latin Americans appears to have been inherited from Neanderthals, a study suggests.
We now know that modern humans interbred with a population of Neanderthals shortly after leaving Africa 60,000-70,000 years ago. This means that Neanderthal genes are now scattered across the genomes of all non-Africans living today. Details of the study appear in the journal Nature. The gene variant was detected in a large genome-wide association study (GWAS) of more than 8,000 Mexicans and other Latin Americans. The GWAS approach looks at many genes in different individuals, to see whether they are linked with a particular trait. People who carry the higher risk version of the gene are 25% more likely to have diabetes than those who do not, and people who inherited copies from both parents are 50% more likely to have diabetes. The higher risk form of the gene - named SLC16A11 - has been found in up to half of people with recent Native American ancestry, including Latin Americans. (via BBC News - Diabetes risk gene ‘from Neanderthals’)
Phobias may be memories passed down in genes from ancestors
Memories may be passed down through generations in DNA in a process that may be the underlying cause of phobias
Memories can be passed down to later generations through genetic switches that allow offspring to inherit the experience of their ancestors, according to new research that may explain how phobias can develop. Scientists have long assumed that memories and learned experiences built up during a lifetime must be passed on by teaching later generations or through personal experience. However, new research has shown that it is possible for some information to be inherited biologically through chemical changes that occur in DNA. Researchers at the Emory University School of Medicine, in Atlanta, found that mice can pass on learned information about traumatic or stressful experiences – in this case a fear of the smell of cherry blossom – to subsequent generations. The results may help to explain why people suffer from seemingly irrational phobias – it may be based on the inherited experiences of their ancestors. (via Phobias may be memories passed down in genes from ancestors - Telegraph)