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Posts Tagged ‘cells

“How is it that you keep mutating and can still be the same virus?”*…

Thale cress (Arabidopsis thaliana)

A common plant has yielded insights that question a fundamental assumption in biology– more specifically, an assumption about the mechanism of natural selection…

A simple roadside weed may hold the key to understanding and predicting DNA mutation, according to new research from University of California, Davis, and the Max Planck Institute for Developmental Biology in Germany.

The findings, published today in the journal Nature, radically change our understanding of evolution and could one day help researchers breed better crops or even help humans fight cancer.

Mutations occur when DNA is damaged and left unrepaired, creating a new variation. The scientists wanted to know if mutation was purely random or something deeper. What they found was unexpected.

“We always thought of mutation as basically random across the genome,” said Grey Monroe, an assistant professor in the UC Davis Department of Plant Sciences who is lead author on the paper. “It turns out that mutation is very non-random and it’s non-random in a way that benefits the plant. It’s a totally new way of thinking about mutation.”

Knowing why some regions of the genome mutate more than others could help breeders who rely on genetic variation to develop better crops. Scientists could also use the information to better predict or develop new treatments for diseases like cancer that are caused by mutation.

“Our discoveries yield a more complete account of the forces driving patterns of natural variation; they should inspire new avenues of theoretical and practical research on the role of mutation in evolution,” the paper concludes.

Evolutionary theory revised? A new study challenges the received wisdom that that DNA mutations are random. Read the underlying paper here.

* Chuck Palahniuk, Invisible Monsters

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As we contemplate change, we might send micro-biological birthday greetings to Ruth Sager; she was born on this date in 1918. A geneticist, she had two careers in science.

In the 1950s and 1960s, she pioneered the field of cytoplasmic genetics by discovering transmission of genetic traits through chloroplast DNA, the first known example of genetics not involving the cell nucleus. The academic community did not acknowledge the significance of her contribution until after the second wave of feminism in the 1970s.

Then, in the early 1970s, she moved into cancer genetics (with a specific focus on breast cancer); she proposed and investigated the roles of tumor suppressor genes.

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“To be overly concerned with the original materials, which are merely sentimental souvenirs of the past, is to fail to see the living building itself”*…

The human body replaces its own cells regularly. Scientists at the Weizmann Institute of Science in Rehovot, Israel, have finally pinned down the speed and extent of this “turnover.” About a third of our body mass is fluid outside of our cells, such as plasma, plus solids, such as the calcium scaffolding of bones. The remaining two thirds is made up of roughly 30 trillion human cells. About 72 percent of those, by mass, are fat and muscle, which last an average of 12 to 50 years, respectively. But we have far more, tiny cells in our blood, which live only three to 120 days, and lining our gut, which typically live less than a week. Those two groups therefore make up the giant majority of the turnover. About 330 billion cells are replaced daily, equivalent to about 1 percent of all our cells. In 80 to 100 days, 30 trillion will have replenished—the equivalent of a new you…

Our Bodies Replace Billions of Cells Every Day: “A New You in 80 Days.”

* Douglas Adams, Last Chance to See

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As we sail on the Ship of Theseus, we might spare a thought for Hans Ernst August Buchner; he died on this date in 1902. A bacteriologist, he was a pioneer in the field of immunology, the first to discover a substance in blood, gamma globulins, natural bactericides capable of destroying bacteria.  He also worked with his brother Eduard Buchner, a chemist who won the Nobel Prize in 1907 for his work on fermentation (which helped pave the way for our understanding of the work of enzymes); Ernst had died in 1902, and so did not share in the honor.

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