Dr. Adeeti Gupta’s Blog (page 2)

Swimming hundreds of feet beneath the ocean’s surface in many parts of the world are prolific architects called giant larvaceans. These zooplankton are not particularly giant themselves (they resemble tadpoles and are about the size of a pinkie finger), but every day, they construct one or more spacious “houses” that can exceed three feet in length.

The houses are transparent mucus structures that encase the creatures inside. Giant larvaceans beat their tails to pump seawater through these structures, which filter tiny bits of dead or drifting organic matter for the animals to eat. When their filters get clogged, the larvaceans abandon ship and construct a new house.

Laden with debris

Laden with debris from the water column, old houses rapidly sink to the seafloor. In a study published in Science Advances on Wednesday, scientists near California’s Monterey Bay have found that, through this process, giant larvaceans can filter all of … Read More »

The recording starts with the patter of a summer squall. Later, a drifting tone like that of a not-quite-tuned-in radio station rises and for a while drowns out the patter.

These are the sounds encountered by NASA’s Cassini spacecraft as it dove through the gap between Saturn and its innermost ring on April 26, the first of 22 such encounters before it will plunge into Saturn’s atmosphere in September. What Cassini did not detect were many of the collisions of dust particles hitting the spacecraft as it passed through the plane of the rings. “You can hear a couple of clicks,” said William S. Kurth, a research scientist at the University of Iowa who is the principal investigator for Cassini’s radio and plasma science instrument.

Their new technique, described in a study published on Thursday in the journal Science, promises to open new avenues of research into human prehistory and was met with excitement by geneticists and archaeologists.

“It’s a bit like discovering that you can extract gold dust from the air,”

said Adam Siepel, a population geneticist at Cold Spring Harbor Laboratory.
“An absolutely amazing and exciting paper,” added David Reich, a genetics professor at Harvard who focuses on ancient DNA.

DNA from fossil bones

Until recently, the only way to study the genes of ancient humans like the Neanderthals and their cousins, the Denisovans, was to recover DNA from fossil bones. But they are scarce and hard to find, which has greatly limited research into where early humans lived and how widely they ranged.

The only Denisovan bones and teeth that scientists have, for example, come from a single cave in Siberia.