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The possibilities of pseudo-peptide-DNA mimics like PNA (peptide nucleic acid) having a role for the prebiotic origin of life prior to an RNA world is discussed on the basis of literature data showing that this type of molecules might have formed on the primitive earth (or other places in the universe), as well as data indicating the possibilities of template-directed PNA chemical replication and ligation. In particular, the merits of an achiral prebiotic genetic material is discussed.

Plant species belonging to divergent branches of the evolutionary tree are known to have independently evolved caffeine production. According to scientists at Western Michigan University, caffeine-producing plants have taken a number of different biochemical routes to synthesize the stimulant. Coffee, tea, cocoa, orange, and guaraná plants make caffeine using an array of enzymes and substrates, the researchers reported in PNAS this week (September 20).

With a dozen or so 140-character dispatches (including three heat maps), Gilad suggested the results published in PNAS were an anomaly-a result of how the tissue samples were sequenced in different batches. If this "batch effect" was eliminated, he proposed, mouse and human tissues clustered in a tissue-specific manner, confirming previous results rather than supporting the conclusions reported by the Mouse ENCODE team.

Using bacteriophages to deliver a specific CRISPR/Cas system into antibiotic-resistant bacteria can sensitize the microbes to the drugs, according to a study published this week (May 18) in PNAS.

Exposing mice to long periods of light each day led them to put on fat, likely because their energy-burning brown fat wasn't in good shape.  Mice exposed to long periods of light didn't eat more or exercise less than mice that kept to a 12-hour day, but their brown fat activity dropped, researchers reported in PNAS this week (May 11).

A cornerstone of modern biomedical research is the use of mouse models to explore basic pathophysiological mechanisms, evaluate new therapeutic approaches, and make go or no-go decisions to carry new drug candidates forward into clinical trials. Systematic studies evaluating how well murine models mimic human inflammatory diseases are nonexistent. Here, we show that, although acute inflammatory stresses from different etiologies result in highly similar genomic responses in humans, the responses in corresponding mouse models correlate poorly with the human conditions and also, one another.

Cattle with the mouse gene SP110 added to their genomes have immune cells that are better at slowing the growth of Mycobacterium bovis and are less susceptible to developing the internal symptoms of tuberculosis (TB), according to a study published this week (March 2) in PNAS.

If the lab technique works in the field, it could offer a new way of stopping the biting insects from spreading malaria to humans, they say. The scientists put a new "resistance" gene into the mosquito's own DNA, using a gene editing method called Crispr. And when the GM mosquitoes mated - their offspring inherited the same resistance, PNAS journal reports. In theory, if these mosquitoes bite people, they should not be able to pass on the parasite that causes malaria.

1 page introduction to epigenetics