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Mind Matters News: Our brains break DNA in order to learn more quickly

MIT News: Neurons and other brain cells snap open their DNA in numerous locations — more than previously realized, according to a new study — to provide quick access to genetic instructions for the mechanisms of memory storage. – David Orenstein, “Memory-making Involves Extensive DNA Breaking” at Mit News (July 14, 2021) Read More ›

Rob Sheldon: Biologists’ use of the term “half-life” shows just how tenuous many of their propositions really are

Recently, our physics color commentator Rob Sheldon took issue with the use of the term “half-life” to describe the survival of DNA in fossils. He says the term has a specific meaning with respect to radioactive decay that just does not apply to other events in nature. In the biology paper at issue, with “half-life” in the name, the authors explain and use the concept in connection with radiocarbon dating: Abstract: Claims of extreme survival of DNA have emphasized the need for reliable models of DNA degradation through time. By analysing mitochondrial DNA (mtDNA) from 158 radiocarbon-dated bones of the extinct New Zealand moa, we confirm empirically a long-hypothesized exponential decay relationship. The average DNA half-life within this geographically constrained Read More ›

A zoologist on that microbe that copies its DNA in a way “unknown to science”

Tim Standish: Simpler systems do not necessarily come first because simple can be a lot harder to come up with than complex. Yes, that seems counterintuitive, but the history of technology bears that out. In some ways you could say the same about art. Read More ›

Does DNA really have a “half life”? Physicist Rob Sheldon is skeptical

Sheldon: "As a physicist, I would like to point out that biologists are misusing the word "half-life". DNA does NOT have a half-life of 521 years. Radioisotopes have a half-life, because the nucleus is unstable to natural decay through the weak force (for isotopes of interest)." He goes on to say that the weak force of the universe "is unaffected by temperature, pressure, time, or chemicals." Not so for DNA. Read More ›

At New Scientist: “single-celled organism that lacks most of the molecular equipment needed to kick-start DNA replication”

It's a protist? “Protists are a group of loosely connected, mostly unicellular eukaryotic organisms that are not plants, animals or fungi. There is no single feature such as evolutionary history or morphology common to all these organisms and they are unofficially placed under a separate kingdom called Protista.” In short, just the sort of life form that might be doing something really different. Because nature is full of intelligence, there are probably many alternative programs out there. It all didn’t just somehow happen randomly once. Read More ›

New form of human DNA found – a four-stranded knot

Researchers: The new shape looks entirely different to the double-stranded DNA double helix... "We think the coming and going of the i-motifs is a clue to what they do. It seems likely that they are there to help switch genes on or off, and to affect whether a gene is actively read or not." Just a random swish of chemicals, right? Read More ›

Archaea microbes have genes like flexible slinkies

They were only discovered in 1977 and they get more unusual all the time: Microbes called archaea package their genetic material into flexible shapes that flop open in unusual ways, Howard Hughes Medical Institute (HHMI) Investigator Karolin Luger reports March 2, 2021, in the journal eLife. “Very much to our surprise, we found that these structures can undergo all sorts of gymnastics,” says Luger, a biochemist at the University of Colorado Boulder. Like DNA in the nucleus of human cells, archaeal DNA coils around proteins like string wrapped around a yo-yo. But there’s another twist, the team found. Those coils of DNA can also spread 90 degrees apart—a phenomenon scientists hadn’t seen before. Such bends in the springlike structures could Read More ›

Sequencing oldest DNA ever from mammoths provides a window into limits on recovering DNA

At Smithsonian Magazine: That Mammuthus columbi originated as a new species, born of a hybridization event, “has major implications for our understanding of the population structure of Pleistocene megabeasts,” MacPhee says. The ancestors of the woolly mammoth and the Krestova mammoth had diverged from each other for about a million years before a population produced a hybrid that was different from both, giving rise to Mammuthus columbi. Read More ›