FOR DAILY USE
Step away from the cookie dough
Eggs, long condemned for making raw cookie dough a forbidden treat,
now share some disease-causing blame with another culprit: flour. The
dry pantry staple can harbor strains of E. coli bacteria that make people
sick, as happened in E. coli outbreaks that sickened 63 people in the
United States and 30 in Canada from 2015 through 2017.
Pinning down tainted flour as the source of the U. S. outbreak required
detailed interviews with people who had fallen ill, researchers recount in
the Nov. 23 New England Journal of Medicine. Two people remembered
eating raw cookie dough before getting sick, says study leader Samuel
Crowe, an epidemiologist at the U.S. Centers for Disease Control and
Prevention in Atlanta. Both sent Crowe pictures of the bags of flour used
to make the batter, and it turned out both bags came from the same plant.
Strains of E. coli that produce dangerous Shiga toxins were isolated from
flour made at the plant. E. coli and other bacteria can survive in a dried
state for months. Once dry flour mingles with eggs or oil, dormant bacteria can reawaken and start to replicate. — Laurel Hamers
Dolly the Sheep’s arthritis
was normal for her age
In the scientific version of her obituary, Dolly the
Sheep was reported to have had severe arthritis in
her knees. That finding and Dolly’s early death from
an infection led many researchers to think that
cloning might cause animals to age prematurely.
But new X-rays indicate that the world’s first
cloned mammal had the joints of a normal sheep her
age. She had only a little arthritis in her hips, knees
and elbows, developmental biologist Kevin Sinclair of the University of
Nottingham in England and colleagues report November 23 in Scientific
Reports. The researchers reexamined Dolly’s remains after finding that
her cloned “sisters” have aged normally without massive arthritis
(SN: 8/20/16, p. 6). Sinclair and colleagues got the skeletons of Dolly,
her naturally conceived daughter Bonnie and two other cloned sheep,
Megan and Morag, from the National Museums Scotland in Edinburgh.
Megan and Bonnie were both older than Dolly when they died and had
more bone damage. Morag died younger and had less damage.
Dolly’s arthritis levels were not excessive, says study coauthor Sandra
Corr. “If there were a direct link with cloning and osteoarthritis, we
would have expected to find a lot worse,” says Corr, a veterinary orthopedic specialist at the University of Glasgow in Scotland. Dolly’s slightly
creaky joints may have stemmed from giving birth to six lambs, including Bonnie. Pregnancy is a risk factor for arthritis in sheep.
From 2015 through 2017, flour tainted by E. coli
sickened more than 90 people in the United States and
Canada, most of whom had eaten raw dough or batter.
This X-ray of Dolly the
Sheep’s limb bones
shows signs of mild
M YSTERY SOLVED
The weird glow of a cosmic blob known as
Hanny’s Voorwerp was a mystery for close to
a decade. Now, Lia Sartori of ETH Zurich and
colleagues have come to a two-part solution.
Hanny van Arkel, then a teacher in the
Netherlands, discovered the strange green
voorwerp, Dutch for “object,” in 2008 as she
was categorizing pictures of galaxies as part of
the Galaxy Zoo citizen science project.
Further observations showed that the object
was a glowing cloud of gas that stretched some
100,000 light-years from the core of a black
hole–containing galaxy nearby. As black holes
eat surrounding gas and dust, friction heats the
doomed material until it glows white hot, forming an active galactic nucleus, or AGN. When
this galaxy’s radiation reached the voorwerp,
the object glowed. Given the voorwerp’s glare,
the AGN should have had the brightness of
about 2.5 trillion suns. Yet its radio emission
suggested it emitted the equivalent of a paltry
25,000 suns. Either the AGN was obscured by
dust, or the black hole slowed its eating about
100,000 years ago, dimming the light.
Sartori and colleagues made the first direct
measurement of the AGN’s intrinsic brightness
using NASA’s NuS TAR telescope to observe the
galaxy in high-energy X-rays that cut through
dust. The team found that the AGN is obscured
by dust and is dimmer than expected; the feeding has slowed way down. The team reports
online November 20 at arXiv.org that the AGN
is as bright as 50 billion to 100 billion suns.
“Both hypotheses that we thought before
are true,” Sartori says. — Lisa Grossman
at left, is glowing
particles of light
from a feasting
black hole in the