Rhesus macaques live in social hierarchies, and for those at the bottom, well, life is not so great. After extensive studies on these macaques, scientists have found that low rank is correlated with poor health as well as physiological changes in stress-related hormones, sex hormones, and white blood cell counts.
In this week’s Proceedings of the National Academy of Sciences, a new study went one step further to show that gene expression, especially that of immune-related genes, was also dependent on social rank. By following female rhesus macaques as their ranks changed over time, the researchers gathered evidence for causal link’s direction, too. It wasn’t that poor health lead to low social rank; it was falling on the social ladder that led to physiological and gene-regulation changes.
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.
Chemotherapy is poison that happens to kill cancer cells faster than it kills healthy cells; that it wreaks havoc on the bodies of patients is unsurprising. But chemo may also affect their unborn children. According to a new study in PNAS, the offspring of mice treated with chemotherapy have higher rates of mutation, even though the offspring themselves were never exposed to the drugs.
The results suggest that these mutations arise from genome destabilization caused by exposure to chemo, rather than just mutated sperm from the treated father. Male mice in the study were exposed to one of three common anticancer drugs—cyclophosphamide, mitomycin C, or procarbazine—and then allowed to mate with untreated females. After sequencing a small piece of DNA from the offspring, the researchers found that mice with treated fathers had mutation rates up to twice that of mice with untreated fathers. Notably, these mutations were present in DNA inherited from both the treated father and untreated mother.
What’s the News: We’ve long had signs that when it comes to inheritance, DNA isn’t the be-all, end-all. Trees that have the exact same genes but were raised in different greenhouses behave differently. Worms with genes that impart long life can pass on that longevity to their progeny—even if they don’t pass on the genes. Both of these phenomena, we’ve discovered, come from epigenetic changes in tags attached to DNA that control whether genes get expressed.
But every now and then we get a whiff of other possible routes for inheritance, even stranger than that. A new paper in Cell reports that worms whose grandparents had the ability to fight viruses using a fleet of tiny RNA molecules retain these molecules even when they don’t have the genes for them. They can pass these molecules down for more than a hundred generations.
Nematode worms live longer if their grandparents had particular genes.
But they don’t need to receive the genes themselves to feel the effects.
What’s the News: Scientists have discovered that worms who’ve been given mutated genes that let them live longer pass on their longevity to their descendants—even when the descendants don’t receive the genes. How does it work?
RNAs from rice can survive digestion and make their way into mammalian tissues, where they change the expression of genes.
What’s the News: It’s no secret that having lunch messes with your biochemistry. Once that sandwich hits your stomach, genes related to digestion have been activated and are causing the production of the many molecules that help break food down. But a new study suggests that the connection between your food’s biochemistry and your own may be more intimate than we thought. Tiny RNAs usually found in plants have been discovered circulating in blood, and animal studies indicate that they are directly manipulating the expression of genes.
Children of older mothers, scientists have long known, are at higher risk for certain genetic disorders such as Down syndrome. But the father’s age is matters, too. As a father’s age increases, research shows, so does his child’s risk of mental illness, schizophrenia and autism in particular. In Scientific American, Nicole Grey explores the link between a father’s age and his child’s health, as well as the tricky questions about what mechanisms are behind the that link: genes, epigenetic changes, environment, or some combination of the three.
All clones are not alike.
What’s the News: Foresters have long noticed that trees with the exact same genes, when raised in separate nurseries, have very different responses to drought. While one shoots up through lean times, the other droops. Why the divergence?
Scientists have now found that twin trees raised separately are, just like human twins, expressing different genes. In other words, nurture is affecting nature.
What’s the News: While you may be able to hide your age with makeup and plastic surgery, don’t think that your deception is foolproof. Researchers have now developed a technique to ascertain your age to within five years using only your saliva. The new method, published in the journal PLoS One, could someday be used by forensic experts to pinpoint the age of crime suspects.
What’s the News: Researchers have known for decades that what a woman eats during her pregnancy can impact her child’s weight later in life. Now, a new study shows a possible mechanism for how mom’s diet affects baby’s weight: Epigenetic changes—changes that can increase or decrease the expression of a particular gene but don’t alter the genetic sequence—to a gene involved in fat metabolism can be passed from mother to child during pregnancy.