ATOM & COSMOS
Neutrinos travel as fast as light
An intergalactic race between light and
a bizarre subatomic particle called a
neutrino has ended in a draw.
The tie suggests that high-energy
neutrinos, which are so lightweight that
they behave as if they’re massless, adhere to a basic rule of physics: Massless
particles travel at the speed of light.
Comparing the arrival times of a
neutrino and an associated blaze of light
emitted from a bright, flaring galaxy
(SN: 8/4/18, p. 6) showed that the neutrino and light differed in speed by less
than a billionth of a percent, physicists
report online July 13 at arXiv.org.
Some theories propose that a “
spacetime foam” might slow particles of very
high energies. Spacetime on extremely
small scales is not smooth, but foamy,
the idea goes. As a result, high-energy
particles could get bogged down, as if
moving through molasses. That effect
could have caused a significant difference between the speeds of the neutrino
and the associated light, which would
build up into a delay over the 4-billion-
light-year trip from the neutrino’s home
galaxy to Earth. But since the flare of
light was spotted around the same time
as the neutrino, there’s no evidence for
such a discrepancy. — Emily Conover
GENES & CELLS
What leeches’ gut bacteria reveal
about antibiotic resistance
Drug resistance in leeches really sucks.
A bacterium found in leeches’ guts
needs exposure to only 0.01 micrograms
per milliliter of ciprofloxacin to become
resistant to the antibiotic. Scientists
thought the bacterium would need expo-
sure to 400 times that amount to develop
drug resistance, Joerg Graf, a biologist at
the University of Connecticut in Storrs,
and colleagues report July 24 in mBio.
In the United States, doctors can
use certain leeches to help patients
heal from reconstructive surgery. The
creatures suck up blood and secrete
anticoagulants, aiding tissue growth.
In the 2000s, researchers noticed an
uptick in drug-resistant infections in these
patients caused by the Aeromonas bacteria
found in Hirudo verbana, a medicinal
leech. Now, scientists have analyzed the
contents of leeches’ stomachs and found
drug-resistant bacteria and low levels of
ciprofloxacin and enrofloxacin, an antibiotic used on poultry farms. The leeches
may have been exposed to the drugs
through poultry blood used as leech food.
Graf suggests that leech farmers eliminate antibiotics from their operations. But
Aeromonas is also found in freshwater settings. “It is concerning because similarly
low amounts [of antibiotics] have been
detected in the environment,” he says.
For now, it’s unclear if other kinds of
bacteria can also become drug-resistant
at such a low threshold. If so, that could
complicate global efforts to prevent drug-resistant infections. — Leah Rosenbaum
BODY & BRAIN
Tick bite linked to heart disease
It sounds bonkers that a tick bite can
make meat eaters allergic to steak, but
it’s true. Now research adds a potential
twist: The source of this tick-related
sensitivity to red meat may also be linked
to coronary artery disease.
A bite from Amblyomma americanum,
the lone star tick, can trigger antibodies
to a sugar called alpha-gal, found in many
mammals but not humans. For some peo-
ple, that produces an allergic reaction to
alpha-gal in red meats. In a new study,
heart patients with the antibodies had
more plaque buildup in their artery walls,
cardiologist Coleen McNamara of the
University of Virginia School of Medicine
in Charlottesville and colleagues report
in the July Arteriosclerosis, Thrombosis
and Vascular Biology. Of 118 people
ages 30 to 80, 31 who tested posi-
tive for the antibodies had about
25 percent more plaque than those
who lacked the antibodies.
The link was strongest in those 65
and younger. For the antibody-positive
people in that group, the plaques were of
the sort more likely to rupture and cause
a heart attack.
The study shows only an association.
To search for a possible mechanism, the
team plans to study alpha-gal and artery
inflammation in mice; inflammatory cells
released via the immune system contribute to plaques. — Aimee Cunningham
MATTER & ENERGY
Physicists find a new quasiparticle
There’s a new clique among quantum
particles in a semiconductor.
Electrons and positively charged holes
in the material’s atomic lattice band
together to create a tight-knit posse
dubbed a collexon, researchers report
Medicinal leeches carry
bacteria that can easily be-
come resistant to antibiotics.