Fears of the fathers

It’s not uncommon for a scientific study to raise more questions than it answers. A fascinating example of this is a study published earlier this month that found that mice can pass a fearful memory down to their offspring — and even the next generation after that. Mice in these later generations froze in fear when they caught a whiff of a certain smell that their fathers (or grandfathers) had learned to associate with an electric shock. Additional experiments showed the same effect when Mom was the one with the scary experience.

The researchers made sure the younger mice had never experienced the smell themselves until it was time to test them, and even mice born through in vitro fertilization who never met their fathers had the fearful memory, seemingly ruling out the possibility that they somehow picked it up from Dad.

The study has spurred an animated debate about how this could happen. The brains of fearful progeny contained more neurons with receptors for the scary smell, the scientists found. They suggest that epigenetic changes — that is, chemical changes to DNA that alter the way genes work — could account for the persistence of memory through the generations. But how such changes could transfer from the brain, where the memory forms, to the sperm and eggs that create the next generation, remains — at least for now — a haunting mystery.

• 

   

  Making organs from stem cells

  This year scientists announced several big steps towards engineering functioning organs from stem cells. The colorful blob above is a mini brain created from stem cells derived from reprogrammed human skin cells. By providing just the right chemical environment, European scientists coaxed the stem cells to become neurons and arrange themselves into different structures that crudely resemble the anatomy of a developing fetal brain. The researchers are using these methods to study what goes wrong in developmental brain disorders like microcephaly, using stem cells from individual patients.

  Meanwhile, researchers in Japan developed functional human liver tissue from reprogrammed skin cells and several teams reported progress on developing kidney tissue. The road to creating transplantable tissues from stem cells is still long, but these are encouraging steps.

  Image: Madeline A. Lancaster
• 

   

  Implantable electronics

  Forget wearable electronics — 2013 was a banner year for electronics designed to work from inside the body. Scientists developed biodegradable circuits that could one day destroy microbes with heat to help heal a wound and dissolve after they’ve done their jobs. They invented flexible electronic tattoosthat could be loaded with enough sensors to make your FitBit seem like a clunky piece of junk. And now we have tiny LED probes and a stretchy foil made of gold nanoparticles that can measure and manipulate the brain. Your cyborg future just got a little closer.