Posts Tagged ‘Genetics’

Posted: January 3, 2013 by Wildcat in Uncategorized
Tags: , , ,

A slight genetic tweak can restart the heart’s own innate pacemaker system, according to new research. Someday, newly jumpstarted internal pacemakers could eliminate the need for electrical implants. In the past couple of years, scientists have figured out how to turn non-beating heart cells into the type that beat, which are called cardiomyocytes. But these cells still have to beat to a specific rhythm, which is controlled by a tiny cluster of about 10,000 cells called the sinoatrial node. When this heart drum major fails, the billions of cardiomyocytes it leads will stop beating properly, leading to an uneven heartbeat or even cardiac arrest. Electronic pacemakers prevent this from happening. (via Scientists Use A Virus To Reconstruct The Heart’s Own Pacemaker | Popular Science)

Advertisements

Posted: December 17, 2012 by Wildcat in Uncategorized
Tags: , , ,

A white tiger is a striking creature. Tigers are always impressive animals, but when you take away the orange, the result is a big cat that looks like a phantom out of a dream. They seem almost magical, and yet I firmly believe that the world would be a better place if there was not a single white tiger in it. There are only about 4,000 tigers, at most, remaining in the wild. Yet there are probably tens of thousands of captive tigers around the world (there is no official census). This would appear to make a compelling case for the existence of zoos and private collections. If tigers can survive and breed well in captivity, then perhaps more can be introduced to the wild when safe habitat becomes available. Yet that system isn’t working the way we think it does. A huge number of the captive tigers are hybrids of various subspecies and are so inbred that they will never be suitable for reintroduction to the wild. No tigers are more emblematic of this problem than white tigers. I recently asked friends on Facebook to write down their thoughts about white tigers without searching for any new information. Some very intelligent people were under the impression that white tigers are a variety of Siberian tiger, camouflaged for a snowy climate. Others applauded zoos with white tigers for supporting conservation of white tigers while lamenting a lag in reintroduction efforts. Only one out of 27 respondents knew that white tigers are not a subspecies at all but rather the result of a mutant gene that has been artificially selected through massive inbreeding to produce oddball animals for human entertainment. This level of misinformation should not come as a surprise. Many of the venues that display white tigers have a long history of shading the truth about their mutants. The Cincinnati Zoo, an otherwise respectable institution, labels their white tigers as a “species at risk!” Nowhere on the zoo’s website or at its tiger enclosures does it point out that this species at risk is in fact an ecologically useless hybrid of Bengal and Siberian strains, inbred at the zoo’s own facility for big money. The Cincinnati Zoo repeatedly bred closely related animals over the past few decades to produce more of the white tigers, which they sold for around $60,000 each. (via White tiger controversy: Zoos shouldn’t raise these inbred, ecologically irrelevant animals. – Slate Magazine)

Scientists have discovered for the first time how humans — and other mammals — have evolved to have intelligence. Researchers have identified the moment in history when the genes that enabled us to think and reason evolved. This point 500 million years ago provided our ability to learn complex skills, analyse situations and have flexibility in the way in which we think. Professor Seth Grant, of the University of Edinburgh, who led the research, said: “One of the greatest scientific problems is to explain how intelligence and complex behaviours arose during evolution.” The research, which is detailed in two papers in Nature Neuroscience, also shows a direct link between the evolution of behaviour and the origins of brain diseases. Scientists believe that the same genes that improved our mental capacity are also responsible for a number of brain disorders. “This ground breaking work has implications for how we understand the emergence of psychiatric disorders and will offer new avenues for the development of new treatments,” said John Williams, Head of Neuroscience and Mental Health at the Wellcome Trust, one of the study funders.

Origin of intelligence and mental illness linked to ancient genetic accident | e! Science News

Everyone has on average 400 flaws in their DNA, a UK study suggests. Most are “silent” mutations and do not affect health, although they can cause problems when passed to future generations. Others are linked to conditions such as cancer or heart disease, which appear in later life, say geneticists. The evidence comes from the 1,000 Genomes project, which is mapping normal human genetic differences, from tiny changes in DNA to major mutations. In the study, 1,000 seemingly healthy people from Europe, the Americas and East Asia had their entire genetic sequences decoded, to look at what makes people different from each other, and to help in the search for genetic links to diseases. Continue reading the main story “Start Quote All of our genomes contain flaws; some of us will carry deleterious variants but will not be at risk of acquiring the associated disease for one reason or another.” Dr Chris Tyler-Smith Wellcome Trust Sanger Institute The new research, published in The American Journal of Human Genetics, compared the genomes of 179 participants, who were healthy at the time their DNA was sampled, with a database of human mutations developed at Cardiff University. It revealed that a normal healthy person has on average about 400 potentially damaging DNA variations, and two DNA changes known to be associated with disease.

We all have hundreds of DNA flaws, UK geneticists say-BBC News –

Posted: December 1, 2012 by Wildcat in Uncategorized
Tags: , , ,

If you could escape the human time scale for a moment, and regard evolution from the perspective of deep time, in which the last 10,000 years are a short chapter in a long story, you’d say: Things are pretty wild right now. In the most massive study of genetic variation yet, researchers estimated the age of more than one million variants, or changes to our DNA code, found across human populations. The vast majority proved to be quite young. The chronologies tell a story of evolutionary dynamics in recent human history, a period characterized by both narrow reproductive bottlenecks and sudden, enormous population growth. The evolutionary dynamics of these features resulted in a flood of new genetic variation, accumulating so fast that natural selection hasn’t caught up yet. As a species, we are freshly bursting with the raw material of evolution. “Most of the mutations that we found arose in the last 200 generations or so. There hasn’t been much time for random change or deterministic change through natural selection,” said geneticist Joshua Akey of the University of Washington, co-author of the Nov. 28 Nature study. “We have a repository of all this new variation for humanity to use as a substrate. In a way, we’re more evolvable now than at any time in our history.” Akey specializes in what’s known as rare variation, or changes in DNA that are found in perhaps one in 100 people, or even fewer. For practical reasons, rare variants have only been studied in earnest for the last several years. Before then, it was simply too expensive. Genomics focused mostly on what are known as common variants. However, as dramatically illustrated by a landmark series of papers to appear this year — by Alon Keinan and Andrew Clark, by Matt Nelson and John Novembre, and another by Akey’s group, all appearing in Science, along with new results from the humanity-spanning 1,000 Genomes Project — common variants are just a small part of the big picture. They’re vastly outnumbered by rare variants, and tend to have weaker effects. The medical implications of this realization are profound. The previously unappreciated significance of rare variation could explain much of why scientists have struggled to identify more than a small fraction of the genetic components of common, complex disease, limiting the predictive value of genomics. (via Human Evolution Enters an Exciting New Phase | Wired Science | Wired.com)

Posted: November 30, 2012 by Wildcat in Uncategorized
Tags: , ,

A recently discovered class of gene may help regulate embryonic development, control the differences between body tissues and even drive animal evolution

THE old saying that where there’s muck, there’s brass has never proved more true than in genetics. Once, and not so long ago, received wisdom was that most of the human genome—perhaps as much as 99% of it—was “junk”. If this junk had a role, it was just to space out the remaining 1%, the genes in which instructions about how to make proteins are encoded, in a useful way in the cell nucleus. That, it now seems, was about as far from the truth as it is possible to be. The decade or so since the completion of the Human Genome Project has shown that lots of the junk must indeed have a function. The culmination of that demonstration was the publication, in September, of the results of the ENCODE project. This suggested that almost two-thirds of human DNA, rather than just 1% of it, is being copied into molecules of RNA, the chemical that carries protein-making instructions to the sub-cellular factories which turn those proteins out, and that as a consequence, rather than there being just 23,000 genes (namely, the bits of DNA that encode proteins), there may be millions of them. The task now is to work out what all these extra genes are up to. And a study just published in Genome Biology, by David Kelley and John Rinn of Harvard University, helps do that for one new genetic class, a type known as lincRNAs. In doing so, moreover, Dr Kelley and Dr Rinn show just how complicated the modern science of genetics has become, and hint also at how animal species split from one another. (via RNA-only genes: The origin of species? | The Economist)

Posted: November 21, 2012 by Wildcat in Uncategorized
Tags: , , ,

The prevailing wisdom has been that every cell in the body contains identical DNA. However, a new study of stem cells derived from the skin has found that genetic variations are widespread in the body’s tissues, a finding with profound implications for genetic screening, according to Yale School of Medicine researchers. Published in the Nov. 18 issue of Nature, the study paves the way for assessing the extent of gene variation, and for better understanding human development and disease. “We found that humans are made up of a mosaic of cells with different genomes,” said lead author Dr. Flora Vaccarino, the Harris Professor of Child Psychiatry at the Yale Child Study Center. “We saw that 30 percent of skin cells harbor copy number variations (CNV), which are segments of DNA that are deleted or duplicated. Previously it was assumed that these variations only occurred in cases of disease, such as cancer. The mosaic that we’ve seen in the skin could also be found in the blood, in the brain, and in other parts of the human body.” (via YaleNews | Skin cells reveal DNA’s genetic mosaic)