29 August 2020 | New Scientist | 15COMMON dolphins (Delphinus
delphis) were once relatively easy
to find throughout the Adriatic Sea,
but large groups were last seen in
the 1940s. There were no reports
of individuals in the area after the
1970s until the late 2000s.
There have been some sightings
since 2009, so Tilen Genov at the
Slovenian Marine Mammal Society
has reviewed them to get a sense of
the current population. He believes
there have been four common
dolphins in the region recently,
three adults and one calf.
Why they have returned is
unclear. Some threats to the
species, such as culling campaigns,
have ceased, says Genov. But
others, like fishing that may limit
their prey, have increased (Aquatic
Conservation, doi.org/d64v).
Is the population of common
dolphins growing in the Adriatic?
“I wouldn’t call it a comeback,” says
Genov. “They are still super rare.” ❚
Marine biology
THE most resilient animal known
to science – the tardigrade – is
yielding its secrets, with the
first work at the atomic level
to investigate how it survives
extreme stress.
Tardigrades are microscopic,
eight-legged animals sometimes
referred to as water bears.
Under environmental stress,
such as dehydration or extremes
of temperature, they shrink into
a “tun” state in which their
metabolism all but stops. In this
state, they can survive without
water for decades, tolerate high
doses of gamma and X-ray
radiation and survive
temperatures from -272°C to 150°C.
They have also breezed through
10 days in the vacuum of space.
In most other organisms, these
sorts of stresses destroy the DNA
in cells, but tardigrades have a
damage-suppressor protein
(Dsup) that somehow shields the
DNA. Now, Marina Mínguez-Toral
and her colleagues at the Centre
for Plant Biotechnology and
Genomics in Madrid, Spain, have
performed a simulation of the
interaction between Dsup and
DNA that suggests an explanation.
The team modelled a system
of two Dsup molecules and DNA,
comprising more than 750,
atoms, which required “days and
days” on a supercomputer. “The
equations of motion must be
solved for each of these atoms50 million times to get a simulation
lasting 100 nanoseconds,” says
Mínguez-Toral.
The researchers’ modelling
shows that the protein is
“intrinsically disordered” and
highly flexible, and seems to be
able to adjust its structure to
precisely fit DNA’s shape. This may
offer the DNA a form of “electric
shielding” that protects it from
damage, says Mínguez-Toral
(Scientific Reports, doi.org/d62f).
Figuring out precisely how
tardigrades tolerate such extremescould be useful in several ways.
“Right now, the main
applications we are actively
working on are the stabilisation
of pharmaceuticals and the
engineering of stress-tolerant
crop plants,” says Thomas Boothby
at the University of Wyoming.
Other possibilities include
cancer treatment. There are
futuristic applications too – people
going to Mars might be modified
to be more resistant to radiation,
for example. In the lab, human
kidney cells have been genetically
modified to express Dsup from
tardigrades, and the cells showed a
reduction of 40 to 50 per cent in the
DNA damage caused by X-rays. ❚Animal biology
Supercomputer reveals tardigrade secrets
Chelsea Whyte
Return of the dolphins?
Four common dolphins spotted in the Adriatic Sea
MARINA^ KOREN,^ M
ORIGENOSRowan Hooper“Modelling the motion
of 750,000 atoms in
and around the DNA
took days and days”