A social wasp emerging from its nest
Yeasts are handy little critters: they help produce the alcohol that make wine and beer so deliciously intoxicating. But how they manage to show up on grapes in vineyards year after year, despite freezing winters when there is little for them to eat, is a bit of a mystery. Scientists thought birds could be keeping the yeasts in their guts through the winter, then sprinkling them (ahem) through vineyards in the spring, but turned out the microorganisms couldn’t survive that long in birds.
Wine grapes in Sicily.
The flavor of sourdough bread, you may have heard, depends on where it is made. Sourdough bakers rely on wild yeasts that have taken up residence in their dough to get it to rise, rather than mixing in commercially available yeasts, and the free-range yeasts, along with plenty of local bacteria, give it a particular tang.
Winemakers have also traditionally relied on wild yeast for fermentation, and a recent survey of Sicilian wine yeasts scraped out of the bottom of old-fashioned fermentation tubs identified 209 wild strains. The researchers, who were interested in seeing whether wild yeasts can produce wine that’s just as good as that produced by commercial strains, arranged a taste test, and they report that some of the Sicilian mavericks were rated more highly than their commercial cousins, especially when it came to flavors central to Sicilian wine.
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.
What’s the News: We walking, talking agglomerations of cells have always thought of multicellular life as a profound jump in evolution. The first organisms were just single cells, but at some point, they began to work together for the good of the whole, divvying up tasks like nutrient transport and cellular messaging. Eventually, these colonies became the complex multicellular life that we know and love.
But maybe being multicellular isn’t as difficult to achieve as we thought. Scientists presenting at the Society for the Study of Evolution conference have, over just a couple months, gotten single-celled yeast to grow into colonies that function as multicellular organisms.
The yeast that causes thrush–an infection of the mouth and tongue–can reproduce homosexually, offering a clue as to why the yeast-caused infection can be so difficult to treat.
When mating, the yeast known as Candida albicans can take one of two sexes: a or alpha. When researchers mixed the two types of yeast, they found that yeast cells of the same sex mated, although not very often, according to the study published in Nature. And they increased this homosexual mingling by boost[ing] a pheromone secreted by “a” cells that draws same-sex cells together [New Scientist]..