New Scientist - USA (2020-03-21)

21 March 2020 | New Scientist | 19

Microbiology

Archaeology Genetics

Strokes now less

deadly in London

Rates of death and

disability caused by

stroke have dropped by

nearly a quarter in the

past 16 years in south

London. The change is

probably due to faster

hospital treatment and

better longer-term care

and rehabilitation (PLoS

Medicine, doi.org/dpqs).

Fish favour small

robot guardians

Salmon seem to prefer

small robots to larger ones,

which could help guide how

we automate fish farms. In

a test with a human diver,

a large robot and a small

robot, farmed salmon beat

their tails slower near the

latter, which suggests they

found it less disruptive

(Royal Society Open

Science, doi.org/dpqt).

Mars mission gets

put back two years

The European Space

Agency and Russia’s

Roscosmos agency have

delayed a planned robotic

mission to Mars. The

second ExoMars mission

was due to launch in July or

August this year, but is now

on hold to 2022. Technical

issues are mostly to blame,

but the coronavirus

outbreak hasn’t helped,

the agencies have said.

Why bacteria make

the ultimate sacrifice

WE KNOW some bacteria self-

destruct when their colony is

attacked by other microbes, but

the reason was unclear. Now it

seems they sacrifice themselves

to save their relatives.

This is rare in nature because it

usually contradicts an individual’s

evolutionary drive to survive and

reproduce. However, many types

of bacteria do self-destruct when

attacked by rival bacteria.

To try to understand why, Elisa

A PREHISTORIC circle made almost

entirely of mammoth bones that

was unearthed in Russia has been

analysed for clues to its purpose.

During the latter part of the Stone

Age, many bone circles were made

in eastern Europe and northern Asia.

One of the best-known sites is

Kostenki 11, south of Voronezh

in Russia. Two bone circles were

found there in 1951 and 1970.

Then in 2014, a third was found

(pictured). Now Alex Pryor at the

University of Exeter in the UK and

his colleagues have investigated it.

The circle is about 12.5 metres

across. Mammoth bones have been

piled up to form a wall 1 to 2 metres

thick and possibly 50 centimetres

high, with no obvious entrance. It is

about 20,000 years old, according

to studies that dated the bones.

Bone circles at other sites have

been interpreted as dwellings.

However, Pryor says that is unlikely

in this case. The internal space is so

large, it would be difficult to build a

roof with prehistoric materials.

It may have been used for

processing food – perhaps tuber

vegetables, similar to parsnips, that

could survive in the frigid climate.

Alternatively, the bone circle could

have had a ritual significance

(Antiquity, DOI: 10.15184/

aqy.2020.7). Michael Marshall

Granato and Kevin Foster at the

University of Oxford developed

a way to visualise this. They took

a strain of E. coli that can self-

destruct in the presence of a

competitor’s toxins and made

the strain turn green when it is

preparing to self-destruct and

pink when it actually does so.

The researchers placed a colony

of the modified bacteria in a dish

next to enemy bacteria – a

different, unmodified strain

of E. coli – and watched them.

The modified E. coli on the front

line, closest to the enemy bacteria,

received a direct hit of the toxins

Half of US would sell

their gene data

A SURVEY of people in the US has

found that 50 per cent would hand

over their genetic data for $95.

Forrest Briscoe at Pennsylvania

State University and his colleagues

asked more than 2000 people, a

representative sample of the US

population, about the use of their

genetic data. They watched a

3-minute video detailing both the

commercial value of genomic data

and privacy issues. This included a

statement that when consumer

genetic data has been sold to

pharmaceutical firms it fetches

around $130 per individual’s data.

The participants were split into

five groups and asked if they

would grant access to their data –

for free or for money – to one of

five types of body: a non-profit

hospital, a pharmaceutical firm, a

tech firm, a university research lab

and a US federal research agency.

While 38 per cent said they

wouldn’t share data, 50 per cent

said they would if paid and 12 per

cent would do it for free. Those

who wanted to be paid expected a

median of $130, but would accept

$95 if they also received a health

and ancestry report based on their

genetic data. The team found the

type of organisation getting the

data made no difference (PLoS

One, doi.org/dprd). JAM

released by their rivals and were

killed straight away. Soon after, the

E. coli just behind the front line,

which were exposed to less toxin,

switched into self-destruct mode.

These bacteria spent an hour

building up their own toxin,

before bursting open and firing

the toxin at the enemy, probably

to help the rest of the colony

survive (bioRxiv, doi.org/dprb).

This makes evolutionary sense,

as bacteria often live in colonies

of identical clones, says Granato.

“It’s like they’re helping their

own genes by killing themselves,”

she says. Alice Klein

Ancient ‘bonehenge’ may

have had ritual significance

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Really brief

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