Page 21 - HOH

A28 SCIENCE
Thursday 6 June 2019
Mutation that protects against HIV raises death rate

By MALCOLM RITTER of death from flu.
AP Science Writer Nielsen and Xinzhu Wei,
NEW YORK (AP) — People also at UC Berkeley, stud-
with a DNA mutation that ied data on about 400,000
reduces their chance of people who'd signed up
HIV infection may die soon- between 2006 and 2010
er, according to a study for the UK Biobank, which
that suggests tinkering with collected extensive infor-
a gene to try to fix one mation on them and is fol-
problem may cause others. lowing their health. They
The study authors cited the compared people who
case of the Chinese re- carry the mutation in both
searcher who tried to pro- copies of their CCR5 gene
duce this mutation in twin to those who carry it in just
girls before their birth, to one copy or neither, and
reduce their risk for HIV. His looked for deaths record-
work, which produced the ed through February 2016.
first gene-edited babies, About 4,000 participants
was widely condemned as carried the mutation in
unethical and risky, and the both copies, of whom 151
new paper illustrates one were dead. Analysis fo-
reason for concern. cused on deaths between
"You should consider all the ages 41 and 76.
effects of mutations you in- In this Oct. 9, 2018 file photo, an embryo receives a small dose of Cas9 protein and PCSK9 sgRNA The study found that par-
duce," said Rasmus Nielsen in a microscope in a laboratory in Shenzhen in southern China's Guangdong province, during ticipants with the muta-
of the University of Califor- work by scientist He Jiankui's team. tion in both copies had a
nia, Berkeley, senior author Associated Press death rate about 20 per-
of the paper , released cent higher than that of the
Monday by the journal Na- different genetic back- different alterations in the fect those cells. The muta- others. A second analysis
ture Medicine. grounds than the Chinese same gene. tion prevents that protein showed that at the time
Nielsen acknowledged girls. The gene is called CCR5. from appearing, and so participants signed up for
that his result cannot be In addition, the people he When it is working normally, sharply reduces the risk of the databank, when their
applied directly to the two studied had inherited a it lets certain cells of the im- HIV infection. average age was about
girls in China. For one thing, specific mutation. The Chi- mune system display a pro- Past studies have suggest- 57, there were fewer peo-
his study focused on a sam- nese scientist tried to cre- tein on their surfaces. HIV ed that carrying the muta- ple with the mutation in
ple of people in the United ate the same mutation, but has co-opted that protein tion has some drawbacks, both copies of the gene
Kingdom who may have failed. The girls now carry to use as a doorway to in- including a heightened risk than one would expect. q

Scientists crack secret of fish's deadly, transparent teeth

By JEREMY REHM of the food chain in their dragonfish themselves
Associated Press deep-ocean realm where — doesn't reflect off the
NEW YORK (AP) — A deep- it's almost pitch black. teeth. Instead, most light
sea fish can hide its enor- To find food or mates, many passes through the teeth so
mous, jutting teeth from animals carry bacteria that they're almost completely
prey because its chompers generate blue or red light. concealed.
are virtually invisible — until That's called biolumines- This, the researchers be-
it's too late. cence. lieve, makes the dragonfish
What's the dragonfish's se- Using microscopes, Meyers a stealthier hunter.
cret? The teeth are trans- and his research team ex- Transparent teeth could
parent, and now scientists amined the teeth of drag- be a common strategy
have discovered how the onfish they had dredged among deep-sea preda-
fish accomplished that up from about a third of a tors, said Christopher Kenal-
trick. mile (500 meters) under- ey, a fish biologist at Boston
Findings were published water off the coast of San College who wasn't part of
This April 2019 photo provided by Audrey Velasco-Hogan shows Wednesday in the journal Diego. the study, noting that some
a dragonfish during a specimen collection session along the Matter. Dragonfish teeth are made other fish share this feature.
coast of San Diego, Calif. The dragonfish is a small of the same materials as Among the most well-
Associated Press predator with jagged, nee- human teeth — a protec- known of the others are
dle-like teeth protruding tive layer of enamel on anglerfish, stubby creatures
from a jaw that can extend the surface and a tough, that wave a glowing rod-
to bite into prey up to half deeper layer of dentin. But like growth from their heads
its body size. the minerals have a much to lure prey.
"They look like monsters," finer microscopic structure Nobody has actually seen
said Marc Meyers of the that is organized more hap- dragonfish feed in the wild,
University of California, San hazardly. but the researchers make
Diego. "But they're mini "That was very surprising to a good case that these
monsters" — about as long us," Meyers said. transparent teeth are an
as a pencil. The result is that light in the evolutionary adaptation
Despite their short stature, environment or from biolu- for hunting in the deep sea,
these fish are at the top minescence— even from Kenaley said.q