WASHINGTON, Jan. 23 -- An international team of researchers from the Boston University and other institutions has uncovered 13 genetic loci, linked to immune function and DNA repair, that are factors in the age of onset of menopause. Menopause -- the cessation of reproductive function of the ovaries -- is a major hormonal change that affects most women when they are in their early 50s. Most prior studies of the age of onset of menopause have focused on genes from the estrogen-production pathway or vascular components. In the new study, published online Jan. 22 in Nature Genetics, the research team identified 13 novel loci associated with menopause onset, while confirming four previously established loci. Most of the 17 loci are associated with genes related to DNA damage repair or auto-immune disease; others are linked to hormonal regulation. The authors said they expected further research to identify "a substantial number of additional common variants" that impact age of menopause, and that many of them will be located in genes identified in their study. The study examined more than 50,000 women of European descent who had experienced menopause between the ages of 40 and 60. The research team noted that a large-scale study of menopause onset in African-American women is underway, which will help to determine whether the genetic variations that affect menopause onset in African-American women are similar or substantially different for women of primarily European descent.
Mar 5, 2012
Int'l study finds new genetic loci associated with menopause onset
Colourful coral could pave way for cancer cure
The vividly fluorescent cluster was found in waters off Lord Howe Island, 600km east of the Australian mainland, with some displaying rich reds that were difficult to find and in high demand for studies of cancer cells.
Egg cells from stem cells can be applied in infertility treatment
Stem cells extracted from human ovaries can be used to generate egg cells to be applied in infertility treatment, said researchers at Massachusetts General Hospital as quoted by media reports Monday. Lead researcher Dr. Jonathan Tilly said: "The discovery of oocyte precursor cells in adult human ovaries, coupled with the fact that these cells share the same characteristic features of their mouse counterparts that produce fully functional eggs, opens the door for development of unprecedented technologies to overcome infertility in women and perhaps even delay the timing of ovarian failure." According to the research team, a rooted belief is that women are born with a complement of egg cells that must last throughout life. The research was funded largely by the National Institutes of Health in U.S. Tilly co-founded a company, OvaScience Inc., trying to develop the findings into fertility treatments.
Y chromosome not to become extinct
The Y sex chromosome of men will not become extinct, according to a study published on Wednesday in the journal Nature. Researchers compared the chromosomes of humans to a Rhesus monkey, a species that separated from human ancestors 25 million years ago, and to chimpanzees, which separated 6 million years ago. The data show that the genetic decay in the Y chromosome was quick at first, but then became minimal in recent history - there is no further gene lost within the past 6 million yeard. "The Y is not going anywhere and gene loss has probably come to a halt. The genes (in Y chromosome) that remain on it have critical biological functions, and that means they are going to survive," said Jennifer Hughes from the Whitehead Institute in Cambridge, Massachusetts, the United States. "We can't rule out the possibility it could happen another time, but the genes which are left on the Y are here to stay," she added. The finding challenged the previous researches which suggested the Y chromosome may become extinct in five million years' time, based on the rate at which genes are disappearing from the chromosome.
UK animal-human hybrid embryos trigger controversy in world
News of animal-human hybrid embryos in UK has caused a stir all around the world, according to a report of British newspaper Daily Mail. 155 "admixed" embryos, containing both human and animal genetic material, have been created since the introduction of the 2008 Human Fertilisation Embryology Act, Daily Mail said. Although the scientific sensation has drawn controversy around the UK, this kind of experiments are licensed in this country. The 2008 Human Fertilisation and Embryology Act legalized the creation of a variety of hybrids, including the creation of "cybrids" in which a human nucleus is implanted into an animal cell. Following are several stills from the U.S. movie "Splice" of 2009:
A still from the U.S. movie "Splice" of 2009 (Photo Source:Chinadaily.com)
A simple method for DNA extraction from formalin-fixed, paraffin embedded tissue blocks
Tissue preparation Deparaffinization method Xylene removal To remove the residual xylene, the samples were washed five times with Ethanol as follows. Tissue lysis Phenol-cholorophorm method For the DNA extraction from cell lysate, phenol-chloroform was used as following. References
The microtubes were then left in a 40 ºC oven to dry the tissues.
DNA reveals Neanderthal extinction clues
Neanderthals were already on the verge of extinction in Europe by the time modern humans arrived on the scene, a study suggests. DNA analysis suggests most Neanderthals in western Europe died out as early as 50,000 years ago - thousands of years before our own species appeared. A small group of Neanderthals then recolonised parts of Europe, surviving for 10,000 years before vanishing. The work is published in the journal Molecular Biology and Evolution. An international team of researchers studied the variation, or diversity, in mitochondrial DNA extracted from the bones of 13 Neanderthals. This type of genetic information is passed down on the maternal line; because cells contain multiple copies of the mitochondrial genome, this DNA is easier to extract from ancient remains than the DNA found in the nuclei of cells. The fossil specimens came from Europe and Asia and span a time period ranging from 100,000 years ago to about 35,000 years ago. The scientists found that west European fossils with ages older than 48,000 years, along with Neanderthal specimens from Asia, showed considerable genetic variation. But specimens from western Europe younger than 48,000 years showed much less genetic diversity (variation in the older remains and the Asian Neanderthals was six-fold greater than in the western examples). In their scientific paper, the scientists propose that some event - possibly changes in the climate - caused Neanderthal populations in the West to crash around 50,000 years ago. But populations may have survived in warmer southern refuges, allowing the later re-expansion. Low genetic variation can make a species less resilient to changes in its environment, and place it at increased risk of extinction. "The fact that Neanderthals in Europe were nearly extinct, but then recovered, and that all this took place long before they came into contact with modern humans, came as a complete surprise," said lead author Love Dalen, from the Swedish Museum of Natural History in Stockholm. "This indicates that the Neanderthals may have been more sensitive to the dramatic climate changes that took place in the last Ice Age than was previously thought." Neanderthals were close evolutionary cousins of modern humans, and once inhabited Europe, the Middle East and Central Asia. The reasons behind their demise remain the subject of debate. The appearance of modern humans in Europe around the time of the Neanderthal extinction offers circumstantial evidence that Homo sapiens played a role. But changes in the climate and other factors may have been important contributors. "The amount of genetic variation in geologically older Neanderthals as well as in Asian Neandertals was just as great as in modern humans as a species," said co-author Anders Gotherstrom, from Uppsala University. "The variation among later European Neanderthals was not even as high as that of modern humans in Iceland." The researchers note that the loss of genetic diversity in west European Neanderthals coincided with a climatic episode known as Marine Isotope Stage Three, which was characterised by several brief periods of freezing temperatures. These cold periods are thought to have been caused by a disturbance of oceanic currents in the North Atlantic, and it is possible that they had a particularly strong impact on the environment in western Europe, note the researchers. Over the last few decades, research has shown that Neanderthals were undeserving of their brutish reputation. (BBC) Researchers recently announced that paintings of seals found in caves at Nerja, southern Spain, might date to 42,000 years - potentially making them the only known art created by Neanderthals. However, this interpretation remains controversial.
Neanderthals were close evolutionary cousins of our own species - Homo sapiens
The last Neanderthals might have held out in southern Europe until 24,000 years ago
Were Neanderthals responsible for these cave paintings of seals at Nerja in southern Spain?
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