The Economist January 22nd 2022 Science & technology 73parumare marked by small changes in the
parasite’s dna, called singlenucleotide
polymorphisms (snps). These are often
copied into the messenger rna(mrna)
molecules that transfer instructions from
dnato a cell’s proteinmaking apparatus.
Their own field of research concerns
molecules called forcedintercalation pep
tide nucleic acids (fitpnas). These resem
ble dnaand rna, but instead of having a
sugarbased backbone from which the
chemical bases that constitute the genetic
code depend, they have a proteinlike one.
This means they bind more strongly to
mrnathan do normal nucleic acids. Add a
fluorescent “reporter” molecule, which re
leases a photon of light when this binding
occurs, and the result is a way of testing for
the presence of particular mrnas.
No hiding place
To create their resistance assay Dr Dzikow
ski and Dr Yavin made fitpnas designed
to bind to the seven commonest snp
marked resistanceinducing mutations,
adding reporters that glowed red for arte
misinin resistance and green to indicate
resistance to chloroquine, currently the
most widely used antimalarial. They then
raised a range of P. falciparumparasites in
their laboratory. Some of these were resis
tant to artemisinin; some to chloroquine;
and some to neither.
Once the cultures were established, the
two researchers incubated them with their
newly created fitpnas for 45 minutes.
That done, they took samples and put them
under a microscope to look for fluores
cence. As they hoped would happen, the
artemisininresistant cultures glowed red,
while the chloroquineresistant ones
glowed green. By contrast, when the cul
tures containing parasites which lacked re
sistance were tested, no glow was visible.
This approach seems something that
could be turned easily into a robust testing
kit for blood taken in local clinics. No fancy
equipment is needed, just a basic light mi
croscope. A patient can then be treated im
mediately with the appropriate drug, re
sulting both in a better outcome for the in
dividual and a negation of the evolutionary
advantage of drug resistance, thus slowing
its spread. A doublewhammy, then, froma
clever piece of molecular manipulation.n
S
mall-scalefisheriessupplymany
people with food. Almost all of those
who ply them rely on gillnets to trap
their prey. But gillnets trap other things,
besides: endangered animals such as
turtles; dangerous ones, such as Hum
boldt squid; and ones that are both en
dangered and dangerous, such as several
types of shark. Everyone involved would
be better off if this did not happen.
Building on studies done both by
himself and by others, to try to avoid the
accidental netting of turtles, Jesse Senko,
a marineconservation biologist at Arizo
na State University, has been investigat
ing the idea of fitting lightemitting
diodes (leds) to nets to ward off other
unwanted bycatch without discouraging
target animals from entangling them
selves. And, as he reports in Current
Biology, it seems to work.
His particular concern was for the
safety of elasmobranchs, as sharks, rays
and skates are called collectively. While
sharks are better known for their sensi
tive nostrils than their keen eyesight—
some species famously being able to
smell traces of blood in vast quantities of
water—many have acute vision, too.
And, though colloquially referred to as
“fish”, elasmobranchs are actually less
closely related to teleosts (the bony fish
that predominate on most fishmongers’
slabs) than turtles are, so their visual
systems might easily be as different. It
thus seemed worthwhile checking to see
whether the trick that worked with tur
tles would work with sharks.
Dr Senko and his colleagues therefore
set up an experiment in the Gulf of Ulloa,offthecoastofBajaCalifornia,in Mex
ico, in which they collaborated with local
fisherfolk to deploy over 10,000 metres
of nets that had had batterypowered
waterproof greenleds clipped onto them
at ten metre intervals. (Green leds are
more efficient than those of other col
ours, and their light better penetrates
seawater.) In half of the nets these lights
were illuminated. The other half were
left unlit, as controls.
Each lit net was paired with an unlit
one, and the two were deployed along
side one another at prime fishing loca
tions. The fishers’ targets were Califor
nian halibut and large groupers. Dr Sen
ko was interested both in what else got
caught and whether the lights decreased
catches of the target species.
On the latter point, reassuringly, they
did not. On the former, the lit nets caught
95% fewer kilograms of sharks, rays and
skates. In particular, several threatened
species, including Munk’s devil ray
(pictured) and the diamond stingray,
turned up less often in the illuminated
than the unilluminated nets. Humboldt
squid were also discouraged. (Cephalo
pods, the group of molluscs to which
they belong, are also well known for their
acute eyesight.)
The advantage from the point of view
of fisherfolk was that they needed to
spend a lot less time clearing these hos
tile bycatches from their nets. And,
crucially, theleds concerned are cheap,
robust and easy to fit. There are also
plans to make them solar powered, for
easy recharging. Here, then, is a conser
vation idea from which everyone wins.MarineconservationA green light for saving sharks
Illuminating fishing nets may reduce by-catchRays of hopeThe Richard Casement internship. We invite
applications for the 2022 Richard Casement
internship. We are looking for a would-be journalist
to spend three months of the summer working on
the newspaper in London (covid-19 permitting;
otherwise remotely), writing about science and
technology. Applicants should compose a letter
introducing themselves and an article of about 600
words that they think would be suitable for
publication in the Science & technology section.
The successful candidate will receive a stipend of
£2,000 a month. Applications must reach us by
midnight on January 28th. They should be sent to:
[email protected]