Free Republic

The water flea Daphnia pulex is a commonly used model organism among ecologists and other environmental scientists. Copyright Holder: P.D.N. Hebert, University of Guelph When sexual species reproduce asexually, they accumulate bad mutations at an increased rate, report two Indiana University Bloomington evolutionary biologists in this week's Science. The researchers used the model species Daphnia pulex, or water flea, for their studies. The finding supports a hypothesis that sex is an evolutionary housekeeper that adeptly reorders genes and efficiently removes deleterious gene mutations. The study also suggests sexual reproduction maintains its own existence by punishing, in a sense, individuals of...

If it has a bill and webbed feet like a duck, lays eggs like a bird or a reptile but also produces milk and has a coat of fur like a mammal, what could the genetics of the duck-billed platypus possibly be like? Well, just as peculiar: an amalgam of genes reflecting significant branching and transitions in evolution. An international scientific team, which announced the first decoding of the platypus genome on Wednesday, said the findings provided “many clues to the function and evolution of all mammalian genomes,” including that of humans, and should “inspire rapid advances in other investigations...

New Genomics Software Infers Ancestry With High Accuracy ScienceDaily (Mar. 27, 2008) — Some people may know where their ancestors lived 10 or 20 generations ago, but the rest of us can learn our distant biological heritage only from our DNA. New genomics analysis software developed by computer scientists at Stanford appears far more adept than prior methods at unraveling the ancestry of individuals. A new paper describes the HAPAA system, which takes its name from "hapa," the Hawaiian word for someone of mixed ancestry. Going back 20 generations the software can identify what continent or broad global region an...

Two studies highlight promise and problems for gene silencing technique. Silencing RNA can be a powerful tool: but how does it work?MEDI-MATION/SPL Researchers have managed to silence tiny chunks of RNA in monkeys using a gene-therapy technique. Their success could offer a new way to treat conditions from cancer to cardiovascular disease. But another study of how RNA interference (RNAi) works — this time in mice — casts some doubt over how well researchers understand the process, and suggests caution in pursuing the technique in people. In the monkey study, researchers looked at microRNAs (miRNAs) — small chunks of RNA...

Networks of genes linked to obesity have been uncovered. Getty Researchers have used a new technique to identify networks of genes linked to obesity in both mice and humans. The procedure is more comprehensive than the traditional method of hunting for genes associated with disease, and is already being used to identify new drug targets. Over the past year, a flurry of studies have revealed genetic variations associated with disease. These ‘genome-wide association studies’ have been used to find variants associated with everything from heart disease to diabetes (See Genome studies: Genetics by numbers).Traditionally, single genes are linked with particular...

Really? THE FACTS It is a basic tenet of human biology, taught in grade schools everywhere: Identical twins come from the same fertilized egg and, thus, share identical genetic profiles. But according to new research, though identical twins share very similar genes, identical they are not. The discovery opens a new understanding of why two people who hail from the same embryo can differ in phenotype, as biologists refer to a person’s physical manifestation. The new findings appear in the March issue of The American Journal of Human Genetics, in a study conducted by scientists at the University of Alabama...

DNA analyses highlight human differences — and similarities. Scientists have taken an unprecedented look at worldwide genetic diversity to illuminate the history of the world’s populations. In two papers — one published today in Science 1, the other published yesterday in Nature 2 — two teams performed the most thorough genetic analysis yet on samples from the Human Genome Diversity Project, which covers more than 50 geographic groups from all over the globe. The group publishing in Nature looked at 29 different populations; the group publishing in Science examined 51. Both analyzed variations in single letters of DNA, called single...

Enlarge ImageAmber waves. Dependence on cereal grains such as barley influenced recent human evolution.Credit: USDA/Doug Wilson In the past 100,000 years, modern humans have colonized the far corners of the globe, adapting to new environments as they migrated. Researchers have long assumed that these dramatic transitions resulted in a sort of accelerated evolution in which genes for traits such as skin color and stature changed rapidly to allow humans to survive in their new habitats. Now, a team of French and Spanish researchers has found powerful new evidence to support this idea, identifying 582 genes that have evolved differently...

Simple cotton swabs would be rubbed inside the mouths of suspects. The collected human cheek cells would then be mined for DNA strands. And those samples would be put together as potential evidence in prosecutions. But those few elemental steps — to be taken by city police officers — would represent a vast expansion of the tools available for solving criminal cases under a proposal laid out by Mayor Michael R. Bloomberg on Thursday in his annual State of the City address. Virtually all suspects would have samples of their DNA taken. The concept leaps far beyond current practice, which...

DR. FEERO is a family physician with a doctorate in human genetics from the University of Pittsburgh. He is a senior adviser for genomic medicine in the Office of the Director at the National Human Genome Research Institute. Our understanding of the genome is changing rapidly and drastically. For starters, the Human Genome Project has revealed that humans are, on a numerical basis, genetically less complex than a mustard plant (Arabidopsis). In fact, our genome contains between 20,000 and 25,000 sequences suggestive of “genes” encoding proteins, whereas Arabidopsis contains about 27,000. If that doesn't make much sense to you, don't...

Environment can change the way our genes work Environmental factors such as stress and diet could be affecting the genes of future generations leading to increased rates of obesity, heart disease and diabetes.A study of people suffering post-traumatic stress disorder (PTSD) after the 9/11 attacks in New York made a striking discovery. The patients included mothers who were pregnant on 9/11 and found altered levels of the stress hormone cortisol in the blood of their babies. This effect was most pronounced for mothers who were in the third trimester of pregnancy suggesting events in the womb might be responsible....

Immortality is within our grasp . . . In Fantastic Voyage, high-tech visionary Ray Kurzweil teams up with life-extension expert Terry Grossman, M.D., to consider the awesome benefits to human health and longevity promised by the leading edge of medical science--and what you can do today to take full advantage of these startling advances. Citing extensive research findings that sound as radical as the most speculative science fiction, Kurzweil and Grossman offer a program designed to slow aging and disease processes to such a degree that you should be in good health and good spirits when the more extreme...