The Chaos Inside a Cancer Cell
A striking feature of many cancer cells is that the DNA in their chromosomes is all jumbled up. Chunks of DNA containing one or more genes have been ripped out of their chromosome and reinserted in a different place. Other lengths of DNA have been transferred to a different chromosome altogether.
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These rearrangements may degrade the cell’s regulatory systems, especially when a rearrangement cuts a gene in half, or separates it from the regions of DNA that control its activity.
Researchers led by Oliver A. Hampton and Aleksandar Milosavljevic at the Baylor College of Medicine in Houston have now compared the genome of a type of breast cancer cell with that of normal cells. They find 157 rearrangements, they report in the current issue of Genome Research.
The graphic summarizes their results. Round the outer ring are shown the 23 chromosomes of the human genome. The lines in blue, in the third ring, show internal rearrangements, in which a stretch of DNA has been moved from one site to another within the same chromosome. The red lines, in the bull’s eye, designate switches of DNA from one chromosome to another.
One of the rearrangements disrupts a gene called RAD51C which is involved in mending serious chromosome breaks, those in which both strands in the DNA are disrupted. The impairment of double strand break repair could be a major cause of all the other rearrangements, the researchers suggest.
Love and Hate: Not Your Fault
Studies showed that part of the brain putamen (connected to the perception of contempt and disgust) and the insula activated when people see someone they hate. These parts of the brain also activated by romantic love. The putamen could also be involved in the preparation of aggressive acts in a romantic context during the rival situation. It is fascinating to see how both hate and love lead one to make irrational, heroic and evil decisions. The two opposite sentiments lead to the same behaviour because they are triggered from the same part of the brain.
Falling Snow Seen on Mars
A robotic science probe on the surface of Mars beamed a laser into the sky and made a surprising discovery: It was snowing.
“Nothing like this view has ever been seen on Mars,” said Jim Whiteway, of York University, Toronto, which oversees the meteorological experiments on NASA’s Phoenix lander.
The spacecraft is on the northern polar region of Mars assessing if conditions were suitable for life to evolve. So far, it has confirmed the existence of water-ice and provided clues that the soil contains clays which, on Earth anyway, only form in the presence of water.
Scientists believe water must be available for life to take root.
The snowfall detected by Phoenix was taking place 2.5 miles above the planet’s surface and vaporized before reaching the ground.
Phoenix’s days are numbered: The sun is sinking toward the horizon, leaving the solar-power probe with less energy. By the end of October, scientists expect they won’t be able to operate Phoenix’s robot arm, which has been digging into the frozen ground to fetch ice and soil samples for analysis.
Meanwhile, evidence that the cold, dry deserts of Mars were once warm and flush with water continues to mount. Last week, scientists announced they had found clusters of stress fractures called deformation bands in the planet’s equatorial region caused by stresses in porous bedrock beneath the surface.
Features of the rocks along the fractures show effects of flowing water.