Synthetic molecules self-assemble into triple helices with new control method - Phys.org

DNA molecules should repel one another because their backbones carry the same negative charge. Yet inside cells, DNA routinely has to approach and recognize other DNA. That happens during processes such as genetic recombination, chromosome organization and gene regulation. Something is clearly up and scientists have long suspected that charged ions help overcome the repulsion, but they had never directly seen the mechanism.

A fossil theropod vertebra about the length of a thumb, found in the Algarve region in southern Portugal, may be the oldest dinosaur remains ever discovered on the Iberian Peninsula. An artist’s impression of Sarcosaurus. Image credit: TotalDino / CC BY 4.0.

Aging is the price paid for the ability of experiencing existence, one might philosophize. Natural cellular aging begins with differentiation. Once a stem cell becomes a specific cell type, it's locked in forever: fat cells can never become muscle cells, no matter how hard one wishes, or pokes and prods at them in front of the mirror. Or so it goes in nature, but scientists can definitely transform cells, as if biologically compensating for all the failed alchemical attempts of the past. Now, scientists have transformed old blood cells into young brain stem cells, which continued to grow younger as they grew older. The researchers, from the University Hospital of Bonn and the University of Bonn, in Germany, described their methods in the journal Aging Cell. Cellular transformations can be done in two main ways. The first, more circuitous route turns a specific cell back into a pluripotent stem cell, or an embryonic "blank slate," and then into a different cell type. The second method involves a "direct conversion," which skips the middle stage and directly transforms a cell into a different type.

Cells constantly recycle proteins and other cellular components. But how do they ensure that the right cargo ends up in the right recycling vesicle—one of the cell's transport carriers? A team at the University of Basel has identified a molecular switch that controls this process. The small protein ARF-1 ensures that recyclable cargo is efficiently loaded into transport vesicles and returned to the cell's surface.