Interesting Reads
Human Genetics
Human Genome
Encyclopedia, on Chromosomes
Stem cells migrate from bone to brain: Autopsies on four dead women have shown for the first time that stem cells in bone marrow can develop into brain cells, not just blood and bone cells as previously thought. The discovery suggests new approaches for repairing damaged or diseased brains. Stem cells themselves could be used, or the signalling chemicals that instruct them to become brain cells, although these have yet to be identified. "I think it's very encouraging to know that there are cells in the human bone marrow that have the capability to reach the brain and become neurons," says Eva Mezey, who led the team that made the discovery at the US National Institute of Neurological Diseases and Stroke in Bethesda, Maryland. The women whose brains were examined by autopsy had all been treated during their lives with bone marrow transplants from men. This meant that any cells the NINDS team found in the brain containing the male Y chromosome must have come from the donated bone marrow. The researchers found such cells and not just in isolation, but in clumps. This suggests the bone marrow stem cells multiplied after reaching the brain. Mezey's hunch is that the raw stem cells circulate all the time, until they are summoned to sites of injury. Once there, they are fashioned into tissue that heals the damage. "There's something that recruits these cells," says Mezey. "There's some factor that says: 'Come in here, we need you'. Then, they receive further orders as to what type of cell to become." "We must now find out what these signals are," she says. Doctors could potentially accelerate healing by injecting extra signalling molecules into damaged tissue. Mezey's proposed strategy for finding the important signals would begin by identifying all the receptors on the surfaces of stem cells. This would reveal which signalling substances the cells are equipped to receive. The next step would be to expose stem cells to each substance in turn, and observe the type of cell they develop into. The NINDS team had already shown that bone marrow cells turn into brain cells in rodents. The new work now shows the same happens in humans. The findings corroborate experiments by Catherine Verfaillie of the University of Minnesota. These showed that special cells with stem-cell like properties, called "multipotent adult progenitor cells", could be isolated from the bone marrow of mice and humans. In mice, Verfaillie showed they turned into virtually any type of tissue. Verfaillie's discovery was reported by New Scientist in January 2002 and raised hopes that, for medical purposes, cells from an adult's bone marrow would be as suitable as the more controversial stem cells harvested from embryos. _______________________________________________________ All this connects with what we've been learning about in class, and how far we've come to understanding, well, basically everything about the human body and all its functions. Now for some more stuff, more on th cloning side, heres a dumbed down article about Dolly, the little lamb that could....... n't live more than a decade. Ok, the server is down for retructuring, well, other news. _______________________________________________________ Three primitive humans who scrambled down a volcano's slopes more than 325,000 years ago left their footprints fossilised in volcanic ash. If the ages of the trails are confirmed, they could be the earliest known footprints of our Homo ancestors. Paolo Mietto of Padua University and his colleagues examined three tracks of footprints on the Roccamonfina volcano in southern Italy, known to locals as "devils' trails". "Because they occur in volcanic rock, they have always been considered supernatural," says Mietto. The scientists say the footprints are fossilised in ash deposited by an eruption that has already been dated as 385,000 to 325,000 years old by radiometric techniques. One person left a track of 27 footprints in a zig-zag pattern, which probably made descent of the steep slope easier. Another track of 19 prints shows a gentle curve, but there are occasional palm-prints where the walker put a hand on the ground probably to avoid slipping. A third track of 10 evenly spaced prints forms a straight line. There are also two animal tracks, possibly made by big dogs or wolves. Short order: The human footprints are about 20 centimetres long and 10 cm wide. Using the average foot length to height ratio of 15 per cent, this suggests the people who made the tracks were only about 135 cm tall (4' 5"). The footprints are just 20 centimetres long (Image: Paolo Mietto and Marco Avanzini) If the ages of the tracks are confirmed, the footprints could have been made by Homo heidelbergensis, thought to have evolved more than 600,000 years ago and migrated to Europe from Africa. "In my view, the [footprint makers] would have been the ancestors of Neanderthals," says Chris Stringer of the Natural History Museum in London. Many anthropologists believe H. heidelbergensis evolved into Neanderthals in Europe, but into modern humans, H. sapiens, in Africa. However, there is no consensus about the migration patterns of our primitive ancestors. In the steps of Lucy: The Italian fossils are much younger than the oldest known hominid footprints - those near Olduvai Gorge in Tanzania are more than 3.7 million years old. They were probably made by two individuals of the distant ancestral species Australopithecus afarensis, of which the famous fossil skeleton Lucy was a member. However, the devils' trails may be the earliest known footprints of a Homo species, which some consider to be the first true humans. Leslie Aiello, an anthropologist at University College London, thinks the people who left the footprints seem surprisingly small for H. heidelbergensis adults. Boxgrove man, another H. heidelbergenesis individual whose tibia was found in England in 1993, seems to have been more than 180 cm tall (six feet). The Italian footprints could have been made by children, suggests Aiello. _______________________________________________________ Well, thats it for this week on Solicitng Chromosomes, all information is from credible sources, not all information made it to this page due to a lengthy amount of typing. But the jist of it is here, so have a great week, and we hope to bring you more exciting stories and news, when the 4th quarter rolls to an end.
