WASHINGTON, D.C. — Helper cells in the brain just got tagged with a new job — forming traumatic memories.

When rats experience trauma, cells in the hippocampus — an area important for learning — produce signals for inflammation, helping to create a potent memory. But most of those signals aren’t coming from the nerve cells, researchers reported November 15 at the Society for Neuroscience meeting.

Instead, more than 90 percent of a key inflammation protein comes from astrocytes. This role in memory formation adds to the repertoire of these starburst-shaped cells, once believed to be responsible for only providing food and support to more important brain cells (SN Online: 8/4/15).
The work could provide new insight into how the brain creates negative memories that contribute to post-traumatic stress disorder, said Meghan Jones, a neuroscientist at the University of North Carolina at Chapel Hill.

Jones and her colleagues gave rats a short series of foot shocks painful enough to “make you curse,” she said. A week after that harrowing experience, rats confronted with a milder shock remained jumpy. In some rats, Jones and her colleagues inhibited astrocyte activity during the original trauma, which prevented the cells from releasing the inflammation protein. Those rats kept their cool in the face of the milder shock.

These preliminary results show that neurons get a lot of help in creating painful memories. Studies like these are “changing how we think about the circuitry that’s involved in depression and post-traumatic stress disorder,” says neuroscientist Georgia Hodes of Virginia Tech in Blacksburg. “Everyone’s been focused on what neurons are doing. [This is] showing an important effect of cells we thought of as only being supportive.”

Immune reactions against proteins commonly used as molecular scissors might make CRISPR/Cas9 gene editing ineffective in people, a new study suggests.

About 79 percent of 34 blood donors tested had antibodies against the Cas9 protein from Staphylococcus aureus bacteria, Stanford University researchers report January 5 at bioRxiv.org. About 65 percent of donors had antibodies against the Cas9 protein from Streptococcus pyogenes.

Nearly half of 13 blood donors also had T cells that seek and destroy cells that make S. aureus Cas9 protein. The researchers did not detect any T cells that attack S. pyogenes Cas9, but the methods used to detect the cells may not be sensitive enough to find them, says study coauthor Kenneth Weinberg.
Cas9 is the DNA-cutting enzyme that enables researchers to make precise edits in genes. Antibodies and T cells against the protein could cause the immune system to attack cells carrying it, making gene therapy ineffective.

The immune reactions may be a technical glitch that researchers will need to work around, but probably aren’t a safety concern as long as cells are edited in lab dishes rather than in the body, says Weinberg, a stem cell biologist and immunologist.

“We think we need to address this now … as we move toward clinical trials,” he says, but “this is probably going to turn out to be more of a hiccup than a brick wall.”

Zeptonewton
ZEP-toe-new-ton n.
A unit of force equal to one billionth of a trillionth of a newton.

An itty-bitty object can be used to suss out teeny-weeny forces.

Scientists used an atom of the element ytterbium to sense an electromagnetic force smaller than 100 zeptonewtons, researchers report online March 23 in Science Advances. That’s less than 0.0000000000000000001 newtons — with, count ‘em, 18 zeroes after the decimal. At about the same strength as the gravitational pull between a person in Dallas and another in Washington, D.C., that’s downright feeble.
After removing one of the atom’s electrons, researchers trapped the atom using electric fields and cooled it to less than a thousandth of a degree above absolute zero (–273.15° Celsius) by hitting it with laser light. That light, counterintuitively, can cause an atom to chill out. The laser also makes the atom glow, and scientists focused that light into an image with a miniature Fresnel lens, a segmented lens like those used to focus lighthouse beams.

Monitoring the motion of the atom’s image allowed the researchers to study how the atom responded to electric fields, and to measure the minuscule force caused by particles of light scattering off the atom, a measly 95 zeptonewtons.