Brrrr! ‘Supercooled’ waters make nearby Antarctic seas seem balmy

Elephant seals help to show that tongues of ultra-frigid seawater are relatively common in the Southern Ocean. Elephant seals help to show that tongues of ultra-frigid seawater are relatively common in the Southern Ocean.


THE PREHISTORIC GLIDERS THAT MISSED THEIR FLIGHT PATH
Natural selection can produce complex traits such as flight, but not every evolutionary journey ends with a falcon's speed or a swallow's aerial acrobatics.
Alexander Dececchi at Mount Marty University in Yankton, South Dakota, and his colleagues analysed the fossilized remains of two species of feathered dinosaur, Yi qi and Ambopteryx longibrachium (artist's impression pictured).
Both lived in what is now China some 160 million years ago, and both weighed less than one kilogram.
These little reptiles might have been able to glide -poorly. An imaging technique called laser-stimulated fluorescence revealed details of the skin between Yi qi's elongated digits that suggest the creature had membranous wings. Models of the performance of these 'wings' suggest that the dinosaurs would have been able to glide only short distances and that they are unlikely to have been capable of flapping or powered flight. They probably walked relatively slowly on the ground, and so lived their lives in trees.
Perhaps unsurprisingly, this lineage quickly went extinct, leaving the skies to the ancestors of today's birds.

ANCIENT ERUPTION CONTINUES TO BLIGHT POMPEII
Volcanic ash that preserved the ancient city of Pompeii for nearly 2,000 years could be eroding the city's murals.
Pompeii was buried when Mount Vesuvius erupted in ad 79. Many of the city's murals (pictured) are degrading, and white crystals precipitating on their surfaces suggest that the paints are interacting with ions dissolved in water.
To investigate, Maite Maguregui and Silvia Pérez-Diez at the University of the Basque Country in Spain and their colleagues used a portable instrument that fires a laser beam at an object, atomizing a tiny amount of material, and analyses the resulting radiation. The team trained the instrument on ash and pumice collected in Pompeii and on white salts on murals at Pompeii's House of Ariadne and House of Marcus Lucretius. Both the volcanic material and the salts contained fluoride and chloride ions, which could have migrated from the volcanic deposits onto the paintings.
The authors suspect that the murals' degradation accelerated after excavations exposed Pompeii to rain and humidity. They hope that the laser-based instrument can identify residual volcanic ash on murals so that it can be removed.

MARKING TIME: HOW TO AGE AN RNA MOLECULE
An RNA-editing tool that 'timestamps' RNA molecules reveals not only which genes in a cell are turned on at any one time, but also when they were turned on.
When a gene is switched on, it triggers the production of RNA molecules that carry the information needed to make a specific protein. Scientists hoping to understand a cellular process often sequence the RNA molecules present at a given moment in a single cell. But researchers have lacked a reliable way to determine when a particular gene became active.
A team led by Edward Boyden at the Massachusetts Institute of Technology in Cambridge and Fei Chen at the Broad Institute of Harvard and MIT, also in Cambridge, tagged genes with a genetic sequence that is recognized by an RNA-editing protein. After these genes had synthesized RNA, the protein made chemical changes to the molecule, adding progressively more edits over time.
When the researchers then sequenced the RNA molecules, they could assume that those with more chemical edits were older than those with fewer edits. The system can narrow down an RNA molecule's age to within roughly one hour. Nature Biotechnol. https://doi.org/ ghf9j9 (2020)