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The tiny hydra, a freshwater invertebrate related to jellyfish and corals, has an amazing ability to renew its cells and regenerate damaged tissue. Cut a hydra in half, and it will regenerate its body and nervous system in a couple of days. Researchers at the University of California, Davis have now traced the fate of hydra’s cells, revealing how three lines of stem cells become nerves, muscles or other tissues.

Celina Juliano, assistant professor in the UC Davis Department of Molecular and Cellular Biology, project scientist Stefan Siebert and colleagues including Jeff Farrell, a postdoctoral researcher at Harvard University, sequenced the RNA transcripts of 25,000 single hydra cells to follow the genetic trajectory of nearly all differentiated cell types.

“The beauty of single-cell sequencing and why this is such a big deal for developmental biologists is that we can actually capture the genes that are expressed as cells differentiate from stem cells into their different cell types,” Juliano said.

Circa 2008


A recent study demonstrates that the use of an acute, localized static magnetic field of moderate strength can result in significant reduction of swelling when applied immediately after an inflammatory injury. Magnets have been touted for their healing properties since ancient Greece. Magnetic therapy is still widely used today as an alternative method for treating a number of conditions, from arthritis to depression, but there hasn’t been scientific proof that magnets can heal.

Lack of regulation and widespread public acceptance have turned magnetic therapy into a $5 billion world market. Hopeful consumers buy bracelets, knee braces, shoe inserts, mattresses, and other products that are embedded with magnets based on anecdotal evidence, hoping for a non-invasive and drug-free cure to what ails them.

“The FDA regulates specific claims of medical efficacy, but in general static magnetic fields are viewed as safe,” notes Thomas Skalak, professor and chair of biomedical engineering at U.Va.

When dinosaurs ruled the Earth, the planet was on a completely different side of the galaxy.

A new animation by NASA scientist Jessie Christiansen shows just how long the dinosaurs’ reign lasted, and how short the era of humans has been in comparison, by tracing our solar system’s movement through the Milky Way.

Our Sun orbits the galaxy’s centre, completing its rotation every 250 million years or so. So Christiansen’s animation shows that last time our Solar System was at its current point in the galaxy, the Triassic Period was in full swing and dinosaurs were just beginning to emerge.

Most people think of space as a flat sheet: You travel in one direction, and you end up far from your starting point. But a new paper suggests that the universe may in fact be spherical: If you travel far enough in the same direction, you’d end up back where you started.

Based on Einstein’s theory of relativity, space can bend into different shapes, so scientists assume the universe must be either open, flat, or closed. Flat is the easiest shape to understand: it is how we experience space in our everyday lives, as a plane in which a beam of light would extend off into infinity. An open universe would be saddle-shaped, with a beam of light bending across the curvature. And a closed universe would be a sphere, with a beam of light eventually looping back around it to meet its origin.

In order to tell which shape our universe is, scientists can look at a phenomenon called the cosmic microwave background (CMB). This is the electromagnetic radiation which remains from the Big Bang, also called “relic radiation.” It fills all of space and can be detected with a sufficiently powerful radio telescope.