New Scientist - USA (2019-10-05)

16 | New Scientist | 5 October 2019

Microplastics

Hopes rise for new

kind of diabetes drug

AN EXPERIMENTAL treatment

for type 2 diabetes appears to

have many beneficial effects.

Tests in animals found that the

drug cuts blood sugar levels and

the amount that mice eat.

Type 2 diabetes develops when

the body fails to respond to insulin

by lowering levels of blood sugar.

It is estimated that 370 million

people worldwide currently have

type 2 diabetes, a number that is

Desert birds really

feeling the heat

BIRD numbers are plummeting

in the Mojave desert in the US as it

gets hotter and drier due to global

warming. They can no longer get

enough water to stay cool.

“The climate change that has

already happened is too intense

for many species,” says Eric Riddell

at the University of California,

Berkeley. “And it’s not nearly as

extreme as what we expect in the

future.” The Mojave, which mainly

spans parts of California and

Nevada, is already the hottest and

driest desert in North America.

To investigate whether climate

change is to blame for dramatic

declines in bird numbers there,

Riddell and his colleagues created

computer simulations of about

50 local species. They used these

to predict how much more

moisture birds lose as it gets

hotter, which dictates how much

water they need to survive.

Wildlife Health

TEA drinkers have been urged

to avoid plastic teabags after

tests found they release billions

of particles of microplastic.

A team in Canada has found

that steeping a plastic teabag at

a brewing temperature of 95°C

releases around 11.6 billion

microplastics – tiny bits of plastic

between 100 nanometres and

5 millimetres in size. That is several

orders of magnitude higher than

the number found in other foods

and drinks, such as bottled water.

Nathalie Tufenkji at McGill

University and her team bought four

different teabags from shops and

cafes in Montreal, cut them open

and washed them, steeped them

in 95°C water and analysed the

water with electron microscopes

and spectroscopy. A control of uncut

teabags was used to check it wasn’t

the cutting that was causing the

leaching of microplastics.

While tiny bits of plastic are also

increasingly found in drinking water,

the World Health Organization says

there is no evidence that this is a

health risk for people.

To test the possible effect of the

particles released by plastic teabags,

Tufenkji and her team exposed

water fleas to the water from the

washed bags (Environmental

Science & Technology, doi.org/

gf8str). “The particles did not kill

the water fleas, but did cause

significant behavioural effects and

developmental malformations,” she

says. However, she says that more

research is needed to understand

possible health impacts in humans.

In the meantime, Tufenkji

suggests avoiding plastic teabags.

Adam Vaughan

One lump or 11 billion?

Teabags that release plastic

expected to double by 2030.

There are already drugs for type

2 diabetes, but better ones are

needed. For instance, metformin

is widely used to lower blood

sugar, but the side effects put off

some people and it doesn’t usually

cause weight loss. In people, losing

weight can be enough to restore

normal blood sugar levels.

So Mark Febbraio at Monash

University in Australia and his

colleagues have developed an

alternative based on proteins with

beneficial effects on metabolism.

To create the drug, they combined

parts of two human signalling

proteins and made various other

tweaks to create a designer protein

that has been called IC7Fc.

When they injected this into

obese mice, it had many benefits,

including lowering blood sugar

levels. The animals also ate less,

shed weight due to fat loss and

had increased bone density

(Nature, doi.org/dbzn). Febbraio

is now trying to get funding for

human trials. MLP

While birds don’t sweat, when

they get too hot they open their

beaks and flutter their throat

muscles to evaporate water to

avoid overheating, similar to

panting in dogs. The team checked

the accuracy of their computer

simulations by exposing some

captive live birds to the kind of

temperatures seen in the desert.

The models suggest the water

needs of birds rises exponentially

as temperatures rise. Mojave birds

now require 10 to 30 per cent more

water each than they did a century

ago. The species with the greatest

increase in water requirements

according to the model were those

that had declined the most, says

Riddell. Predatory birds including

prairie falcons, American kestrels

and turkey vultures are among

those worst hit (PNAS,

DOI: 10.1073/pnas.1908791116).

Over the next century, these

birds could need 50 to 80 per

cent more water. However, rainfall

is expected to continue declining

in the Mojave. Michael Le Page

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