BEIJING, March 27-- Scientists used a DNA-decoded method to investigate an ancient human who has been discovered in a cave in southern Siberia, according to British newspaper Daily Mail.
Living 6.8million years ago this is Sahelanthropus tchadensis. Parts of its jaw bone and teeth were found nine years ago in the Djurab desert, Chad, and from this scientists created this model head.(Photo Source:CRIOnline.com)
The mysterious human, who lived alongside our ancestors tens of thousands of years ago, earned a nickname “X-Woman”.
Through analysing DNA from a fossilized finger bone, researchers found it doesn't match modern humans or Neanderthals, two species that lived in that area around the same time - 30,000 to 50,000 years ago.
The Siberian species lineage may split off from the branch leading to moderns and Neanderthals a million years ago, the researchers calculated.
And they also said that it doesn't seem to match the history of human ancestors previously known from fossils.
Researchers presumed that the Siberian species may be brand new, although they cautioned that they're not ready to make that claim yet.
This paleoanthropological breakthrough may rewrite mankind's family tree.
Deep in the forests of Michoacán, several hours drive north of Mexico City, tourists watch millions of Monarch butterflies as they cling to fir trees, gather on bushes, or take off in flight.
The striking black and orange insects winter in these mountains every year, traveling up to 4,800 kilometers to get here, from as far away as Canada. They stay through the winter, then, in the spring, the females leave these fir tree forests and head as far north as Kansas, to lay their eggs on milkweed plants.
It's an odyssey that inspires Chip Taylor, director of the Monarch Watch program in Lawrence, Kansas, over 2,000 kilometers north of the butterflies' winter habitat.
Earl Richardson
Chip Taylor is director of the Monarch Watch program in Lawrence, Kansas.
"We see them usually between the 14th and 21st of April if they get this far north," he says, adding that many of them can barely fly after their journey. "A lot of those butterflies are so tattered and broken, that they're crawling from milkweed and milkweed to lay the eggs." A journey guided by the senses
Just as remarkable as the distance they fly is how the butterflies navigate. After all, they don't have guides, or maps, or GPS equipment. Instead, they use sight, smell, touch and other senses to find their way. To study that, butterfly scientists track the insects' normal flight paths, then they confuse them and track their path again.
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Taylor says his research teams used this method to discover that butterflies need accurate information about the earth's magnetic fields. "Ten seconds of exposure to the strong magnetic field was enough to totally disorient the butterflies. They could not maintain a course," he reports.
Sunlight matters, too, and by manipulating artificial sunlight, scientists can fool butterflies into traveling in the wrong direction.
At the University of Massachusetts, neuroscientist Steven Reppert studies the Monarch butterfly's migration with a sophisticated apparatus. It's a kind of flight simulator; essentially a large barrel. His research team connects a butterfly to a thin wire tether to track its normal flight path and then to track how that path changes once they've confused it.
Based on flight simulation studies, Reppert says that Monarchs use visual cues about the daylight sky to set their internal compass, as well as their brain's circadian clock, which regulates hormones and behavior. Reppert says researchers thought they had this control system mostly figured out. But then they took a closer look at the insects' antenna.
VOA - S. Schlender
These Monarch butterflies are wintering in the mountains several hours drive north of Mexico City, some traveling from as far away as Canada.
A multipurpose organ for navigation
"The antenna are really remarkable organs," Reppert says. "They're odor sensors. But they do a lot more than that. They can sense vibrations, they can act as ears, they can sense changes in barometric pressure, so there's a number of things that the antennae can do."
To study these abilities, Reppert's team decided to confuse the butterflies, at least a little, by removing their antenna. But this did more than eliminate their sense of smell and vibration. It totally befuddled their navigation.
Reppert says, "This finding was actually quite heretical to us. We did not know quite what to do with it at the time." So, they devised another experiment.
Dr. Thomas Barnes/USFWS
Removing the Monarchs' antenna not only eliminated their sense of smell and vibration, it also befuddled their navigation.
On the chance that smell mattered more than they had realized, the researchers painted butterflies' antenna to block their odor receptors. And just in case sunlight played a role, Reppert's team used clear paint on some butterflies' antenna and black paint on others. The clear paint allowed in daylight, and those butterflies navigated normally. The ones painted black could not.
Antenna data leads the way
This meant that the Monarch's antenna can detect light. But an even bigger surprise was up ahead. Scientists knew that the circadian clock in the insect's brain responds to light signals from the eyes. They had assumed that that system provided all the daylight data that the butterfly's navigation system needed.
But it turns out that the circadian clock signals produced in the butterfly's antenna are at least as crucial as the clock in its brain. The butterfly's bug-sized GPS needs that antenna data, so when winds and other surprises hit, the Monarch still flies in the right direction.
As for how all these pieces work together, Reppert says, the clues are tantalizing. "The antenna are talking to the brain and controlling the behavior in a very specific way. And we need to understand that."
Reppert's lab plans more experiments. He predicts they'll find that the ability of the Monarch's antenna to sense odors and magnetic waves may also help them set the course for the day. And he says the lessons learned will help us understand the role of circadian clocks in other animals, including people.
This lecture by Dr. Nadia Rosenthal discusses the importance of adult stem cells in the tissue maintenance, development and regeneration. Part 3 of 6. HHMI description: Mature organisms have stem cells of various sorts, called adult stem cells. Adult stem cells supply cells that compensate for the loss of cells from normal cell death and turnover, such as the ever-dying cells of our skin, our blood, and the lining of our gut. They are also an essential source of cells for healing and regeneration in response to injury. Some animals, such as sea stars, newts, and flatworms, are capable of dramatic feats of regeneration, producing replacement limbs, eyes, or most of a body. It is an evolutionary puzzle why mammals have more limited powers of regeneration. Researchers are interested in pinpointing where adult stem cells reside and in understanding how flexible adult stem cells are in their ability to produce divergent cells such as muscle and red blood cells. Understanding the sources and the rules for the differentiation of adult stem cells is essential for tapping their therapeutic potential. Since consenting adults can provide adult stem cells, some people think that adult stem cells may be a less controversial area of Research than embryonic stem cells.Date: 2008-09-03 23:50:28 - Added by: ebiotek
If you\'ve ever wondered how to clone a sheep, this simple step-by-step demonstration is just what you\'ve been looking for. Ten simple steps is all it takes to go from egg cell to infant sheep clone. DO NOT ATTEMPT AT HOME.
Nuclear Transfer is a form of cloning. The steps involve removing the DNA from an oocyte and while(unfertilized egg), and injecting the nucleus which contains the DNA to be cloned. In rare instances, the newly constructed cell will divide normally, replicating the new DNA while remaining in a pluripotent state. If the cloned cells are placed in the uterus of a female mammal, a cloned organism develops to term in rare instances. This is how Dolly the Sheep and many other species were cloned. Alternatively, if cells are extracted from the cloned cells during very early embryonic stages (blastocyst or morula), embryonic stem cells can be created. These cells can be grown in laboratories indefinitely and can theoretically be made into any of the 200+ cell types in the mammalian body, and thus are an extraordinary tool for biologists as well as a therapeutic agent with the potential to treat currently untreatable medical conditions.
This lecture by Dr. Nadia Rosenthal discusses the importance of adult stem cells in the tissue maintenance, development and regeneration. Part 2 of 6. HHMI description: Mature organisms have stem cells of various sorts, called adult stem cells. Adult stem cells supply cells that compensate for the loss of cells from normal cell death and turnover, such as the ever-dying cells of our skin, our blood, and the lining of our gut. They are also an essential source of cells for healing and regeneration in response to injury. Some animals, such as sea stars, newts, and flatworms, are capable of dramatic feats of regeneration, producing replacement limbs, eyes, or most of a body. It is an evolutionary puzzle why mammals have more limited powers of regeneration. Researchers are interested in pinpointing where adult stem cells reside and in understanding how flexible adult stem cells are in their ability to produce divergent cells such as muscle and red blood cells. Understanding the sources and the rules for the differentiation of adult stem cells is essential for tapping their therapeutic potential. Since consenting adults can provide adult stem cells, some people think that adult stem cells may be a less controversial area of research than embryonic stem cells.
This lecture by Dr. Nadia Rosenthal discusses the importance of adult stem cells in the tissue maintenance, development and regeneration. Part 1 of 6. HHMI description: Mature organisms have stem cells of various sorts, called adult stem cells. Adult stem cells supply cells that compensate for the loss of cells from normal cell death and turnover, such as the ever-dying cells of our skin, our blood, and the lining of our gut. They are also an essential source of cells for healing and regeneration in response to injury. Some animals, such as sea stars, newts, and flatworms, are capable of dramatic feats of regeneration, producing replacement limbs, eyes, or most of a body. It is an evolutionary puzzle why mammals have more limited powers of regeneration. Researchers are interested in pinpointing where adult stem cells reside and in understanding how flexible adult stem cells are in their ability to produce divergent cells such as muscle and red blood cells. Understanding the sources and the rules for the differentiation of adult stem cells is essential for tapping their therapeutic potential. Since consenting adults can provide adult stem cells, some people think that adult stem cells may be a less controversial area of research than embryonic stem cells.
This lecture by Dr. Nadia Rosenthal discusses the importance of adult stem cells in the tissue maintenance, development and regeneration. Part 6 of 6. HHMI description: Mature organisms have stem cells of various sorts, called adult stem cells. Adult stem cells supply cells that compensate for the loss of cells from normal cell death and turnover, such as the ever-dying cells of our skin, our blood, and the lining of our gut. They are also an essential source of cells for healing and regeneration in response to injury. Some animals, such as sea stars, newts, and flatworms, are capable of dramatic feats of regeneration, producing replacement limbs, eyes, or most of a body. It is an evolutionary puzzle why mammals have more limited powers of regeneration. Researchers are interested in pinpointing where adult stem cells reside and in understanding how flexible adult stem cells are in their ability to produce divergent cells such as muscle and red blood cells. Understanding the sources and the rules for the differentiation of adult stem cells is essential for tapping their therapeutic potential. Since consenting adults can provide adult stem cells, some people think that adult stem cells may be a less controversial area of research than embryonic stem cells.
Genes and Disease is a collection of articles that discuss genes and the diseases that they cause. These genetic disorders are organized by the parts of the body that they affect. As some diseases affect various body systems, they appear in more than one chapter.
With each genetic disorder, the underlying mutation(s) is discussed, along with clinical features and links to key websites. You can browse through the articles online, and you can also download a printable file (PDF) of each chapter.
From Genes and Disease you can delve into many online related resources with free and full access. For example, you can visit the human genome to see the location of the genes implicated in each disorder. You can also find related gene sequences in different organisms. And for the very latest information, you can search for complete research articles, and look in other books in the NCBI Bookshelf. Currently over 80 genetic disorders have been summarized, and the content of Genes and Disease is continually growing.
The sequence of the human genome is providing us with the first holistic view of our genetic heritage. While not yet complete, continued refinement of the data bring us ever closer to a complete human genome reference sequence. This will be a fundamental resource in future biomedical research.
The 46 human chromosomes (22 pairs of autosomal chromosomes and 2 sex chromosomes) between them house almost 3 billion base pairs of DNA that contains about 30,000 - 40,000 protein-coding genes. The coding regions make up less than 5% of the genome (the function of the remaining DNA is not clear) and some chromosomes have a higher density of genes than others.
Most of the genetic disorders featured on this web site are the direct result of a mutation in one gene. However, one of the most difficult problems ahead is to find out how genes contribute to diseases that have a complex pattern of inheritance, such as in the cases of diabetes, asthma, cancer and mental illness. In all these cases, no one gene has the yes/no power to say whether a person has a disease or not. It is likely that more than one mutation is required before the disease is manifest, and a number of genes may each make a subtle contribution to a person's susceptibility to a disease; genes may also affect how a person reacts to environmental factors. Unraveling these networks of events will undoubtedly be a challenge for some time to come, and will be amply assisted by the availability of the sequence of the human genome.
Discovery could revolutionize cancer care, saving millions of lives
Carol Pearson | Washington 19 December 2009
It is being called a scientific breakthrough. British researchers say they have mapped the entire genetic code for two types of cancers -- small cell lung cancer and melanoma, the most deadly type of skin cancer.
All cancers are caused by changes in the DNA of cells. DNA carries the cells' genetic information. That information changes when cells gradually mutate from normal to abnormal and then to malignant over time.
Scientists say if they could only crack the genetic codes of different types of cancers, they could save millions of lives.
Blood tests could spot tumors early on. And treatment would be far more successful. Dr. Jeanny Aragon-Ching is an oncologist at the George Washington University Medical Center. She says this discovery is a step toward an era of personalized medicine. "That is the thrust now because, for instance, for different types of cancers, we have different types of drugs that target different domains or mutations," she said.
The more information doctors have about how cancer cells develop, the more precisely they can prescribe a treatment to target those particular cells.
British scientists found 30,000 mutations in melanoma, a type of skin cancer that accounts for 75 percent of skin cancer deaths. They also found 23,000 mutations in small cell lung cancer. But not all of these mutations cause cancer. "It is the role of physicians and scientists to find out which of those mutations are the driving force, or the driving mutation that actually led to the cancer," she said.
Eventually, scientists might be able to target pre-cancerous cells and prevent deadly tumors from forming. But that day is still far away. "As an oncologist, my goal would be to one day see that we can transform cancer into a chronic disease. Cure is probably too generous of a word the way I see it, but to convert it to something more like chronic disease that is treatable," she said.
Just like high blood pressure that can be controlled with medicine, cancer could be a disease without the suffering we associate with it. Medical scientists the world over are now working to catalogue all the genes that mutate in many types of cancer as part of an International Cancer Genome Consortium. In the United States they are studying cancers of the brain, ovaries and pancreas.
In addition to lung cancer and melanoma, scientists are examining the DNA of breast cancer, as well as cancers of the liver, the mouth and the stomach. "I think each step forward is a step toward our goal, our ultimate goal, which is to relieve the suffering from cancer," she said.
Paleontologists say the dinosaur they call Tawa, was about the size of a large dog, but with a longer tail.
Jessica Berman | Washington , from VOA
Scientists have discovered the fossilized remains of a new meat-eating dinosaur in a quarry in New Mexico. They say the finding sheds light on the evolution of these extinct creatures.
Paleontologists say the dinosaur they call Tawa, named for the Hopi Native American sun god, was about the size of a large dog, but with a longer tail, stood about 70 centimeters tall at the hips and was two meters long. The two-legged creature also had razor-sharp teeth for eating meat.
Scientists conducting an analysis of the newly-discovered, 215 million year old fossils and other early dinosaur remains say Tawa also had the characteristics of two other dinosaurs - the giant, plant-eating sauropod and the horned Triceratops.
They believe Tawa is the common ancestor of both dinosaur groups that migrated from Argentina to other parts of the world during the Pangea period, between 200 and 300 million years ago, when geologists say the Earth's continents were compressed into a single landmass.
The fossil discovery suggests that Tawa also used a land bridge from South America to make its way to North America, when Tyrannosaurus Rex began evolving into modern day birds, according to Sterling Nesbitt, a researcher at the University of Texas who led a team of excavators.
"Tawa is a little bit of a surprise because it's preserving these very early traits that we see in dinosaurs while living with animals that are much more closely related to bird," said Nesbitt.
According to Nesbitt, Tawa might answer important questions about a dinosaur called Herrerasaurus, which was discovered in Argentina in the 1960s.
Herrerasaurus has traits like T. Rex - including sharp claws and teeth - but lacks other characteristics of the carnivore. Scientists hope to determine whether Herrerasaurus is a direct descendant of Tawa or part of a different species of dinosaurs.
Nesbitt say the Hayden Quarry in northern New Mexico, where the ancient fossils were unearthed, is a rich bed containing other prehistoric bones and artifacts. He says he plans to continue digging at the site to learn more about Tawa.
"We want to know how it grew, how the features changed as the animal got older," he said. "We also want to look at the anatomical details."
A description of the new dinosaur species is reported this week in the journal Science.
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