The hard-working precursor cells that produce sperm just can’t catch a break. Since men make sperm throughout their lives, these cells have to divide again and again, sending one copy of themselves off to become sperm cells each time. DNA doesn’t always copy itself perfectly, so over the years, genetic errors pile up. And now a new study has quantified just how many mutations sperm will accumulate—and pass on to any offspring—for fathers of various ages. Scientists think that these mutations may be partly to blame for the fact that children with older fathers tend to have higher rates of bipolar disorder, schizophrenia, and autism.
A blond boy from the island of Vanatu
In many places, blond hair usually goes with white skin and European ancestry. But in the islands of Melanesia and among the Aborigines of Australia, blond hair crops up on dark-skinned people with no known European heritage. Scientists have long wondered, is it because they have some (very, very) long-lost European ancestors? Or did blond hair arise from a genetic mutation in the population there?
A paper published in Science this week lays that question to rest. The researchers found that blond Solomon Islanders in Melanesia have a single amino acid difference in the tyrosinase-related protein 1 (TYRP1) gene, which codes for an enzyme involved in the production of the pigment melanin. Other mutations in TYRP1 can give people albinism; this one gives them light-colored hair. The mutation is recessive, so only people who have two mutant copies of the TYRP1 gene are blond.
Yeast under a microscope.
What’s the News: Prions get a bad name—the very word is a portmanteau of “protein” and “infection,” which suggests that they’re up to no good. And there’s obviously some truth to this: Prions are a type of protein that have alternative folded forms, and if they aggregate into insoluble clumps, they can cause problems like mad cow disease. But prions might also be a key part of evolution. A new survey published in Nature found prions in 1/3 of yeast strains, and 40% of the traits they conferred were beneficial.
The strangest thing about this Chinese boy’s light blue eyes is not their color. It’s the purported fact that he can see in the dark. His eyes are just like cat eyes, glowing blue-green when you shine a light in them, says this clip from China’s state-run English TV channel. The boy can catch crickets in the dark without a flashlight and even completes a writing test in a pitch-black stairwell. True, or too good to be?
Natalie Wolchover at Life’s Little Mysteries has rounded up some experts and their collective reaction seems to be, “Hmm…” (It doesn’t help that this video has been posted on YouTube under the name, “Alien Hybrid or Starchild Discovered in China? 2012.”) One possibility they consider is whether the boy has a mutation that produced something like a tapetum lucidum, an extra layer of tissue that helps cats see in the dark. James Reynolds, a pediatric ophthalmologist at State University of New York in Buffalo, puts a stop to that idea:
Because of two missing amino acids, this tomcod can swim through PCBs—and survive.
PCBs are nasty pollutants—they mess with hormones and have been linked to cancer—but until they were banned in 1977, dumping them in US rivers was a common practice for companies like GE. While plenty of wildlife suffered from ingesting PCBs, some fish in the Hudson and other be-sludged rivers evolved an immunity to the poisons, a intriguing example of quick adaptation that scientists have been watching with interest. A recent Economist article focusing on this research describes the fascinating genetic ju-jitsu that allows fish in the Hudson and in the harbor at New Bedford, MA, to keep themselves alive in PCB-contaminated waters. Read More