New Scientist - 26.10.2019

10 | New Scientist | 26 October 2019

ECOTOURISTS are getting too

close to mountain gorillas, risking

passing on potentially deadly

human coughs and colds – and

the proof is on Instagram.

A search of the social media site

has turned up hundreds of shots

of people standing closer than

the recommended 7 metres away

from the apes. Part of the problem

is people seeking the perfect

selfie to post online, says Gladys

Kalema-Zikusoka at the Ugandan

charity Conservation Through

Public Health.

Often the close encounters

are initiated by young gorillas.

“Juvenile primates tend to be

more inquisitive,” says Gaspard

van Hamme at Oxford Brookes

University, UK, one of those who

conducted the analysis.

Mountain gorillas, which are

found in Rwanda, Uganda and the

Democratic Republic of the Congo

(DRC), are classed as endangered,

with just 1004 animals at the

last count. Their numbers have

been slowly rising since the 1980s,

although outbreaks of respiratory

infections have been increasing

in the past few years.

In one case in Rwanda, 11 out

of 12 animals in a group had

runny noses and were coughing

and lethargic. Veterinarians

managed to give antibiotics to

five, but two untreated gorillas

died. Post-mortems showed they

were infected with a virus that

normally affects people called

human metapneumovirus.

All three countries permit

treks into the forests to see

gorillas, but people are meant

to keep at least 7 metres away. In

the DRC, they are also supposed

to wear face masks.

To see if the rules are being

followed, van Hamme and his

colleagues searched Instagram

for pictures of people on treks

since 2013. For any image that

showed a person and a gorilla,

the researchers estimated

the distance between them.

Out of 643 photographs, nearly

every one showed people closer

than 7 metres and 20 showed

physical contact. Of those taken

in the DRC, about two-thirds

showed people wearing face

masks, but no one used them in

the other two countries. The team

presented its work at a European

Federation for Primatology

meeting in Oxford, UK.

People may be wearing face

masks most of the time and just

taking them off for a photo,

says van Hamme. “But that still

presents a risk.”

The tourism should continue,

though, as it brings much needed

money into conservation work,

says Kalema-Zikusoka.

It is up to tour sites to enforce

the rules more strictly, says

Fabian Leendertz at the Robert

Koch Institute in Berlin. “There’s

big variability among the guides.

People are more likely to give a

guide a tip if they get a good selfie.”

Van Hamme believes people

who care about protecting

gorillas would be willing to wear

masks and keep their distance if

the reasons are explained. “I don’t

think the experience would be

less enjoyable. But the pictures

may get less likes on Instagram.” ❚

“Outbreaks of respiratory

infections have been rising

among mountain gorillas

in the past few years”

Animal health

Clare Wilson

CHRISTOPHE COURTEAU/NATURE PICTURE LIBRARY

News

Gene editing

CRISPR tweak

makes it better

and faster

THE CRISPR genome-editing

technique revolutionising biology

just got a major upgrade.

A new variant, called prime

editing, makes it possible to add

or delete short DNA sequences, or

change one DNA letter to another,

with fewer unwanted side effects.

The technique, devised by

Andrew Anzalone at the Broad

Institute in Massachusetts, gets

closer to the ideal form of genome

editing, which would work like

the “find and replace” command

in a writing app.

Use of CRISPR has grown rapidly

since it was devised in 2012

because it made the “find” part

far cheaper and easier. CRISPR

exploits a protein called Cas9,

which hooks up with a piece of

guide RNA and seeks out matching

DNA sequences in a cell’s genome.

The “replace” part is harder. Cas

is usually used solely to introduce

mutations that can disable a gene,

by cutting the cell’s DNA. It is rare for

any piece of DNA added at the same

time to be spliced into the cut site.

Anzalone and his colleagues have

altered the Cas9 protein and fused

it with another protein so it works

differently (Nature, doi. org/dczp).

DNA’s double-stranded structure

helps cells repair some forms of

damage: because the two strands

are complementary, the cell can

sometimes fix an error in one by

referencing the other. A normal

Cas9 cuts both strands, introducing

mutations during repairs.

Anzalone’s hybrid protein uses

an extra segment in the guide RNA,

which adds a section of DNA to the

target site. The protein then cuts

the opposite DNA strand, prompting

the cell to repair it using the added

DNA as the template.

In effect, Anzalone has made

CRISPR fully programmable.

The sequence of the guide RNA

determines both the site of an

edit and the change to be made. ❚

Michael Le Page

CRISPR is a

powerful tool

for altering DNA

and changing or

disabling genes

BETTER$SETTLE$FELLOW/SPL

Tourists taking selfies risk

giving gorillas deadly diseases