2019-06-22_New_Scientist

22 June 2019 | New Scientist | 15

Physiology

Michael Le Page

THERE is a distinct type of fat in our

bones that behaves differently from

any other. These peculiar fat cells, or

adipocytes, grow larger, not smaller,

when we starve – and now we know

they produce different proteins too.

The main function of fat is to

store energy and release it when

needed, says Catherine Muller at the

University of Toulouse, France. This

is what most of the “white fat” in

our bodies – found under our skin

and around internal organs – does.

We have suspected for a few

decades that some of the fat cells

inside our bone marrow may be

different. Animal studies showed

these cells grow bigger when

animals starve, even though fat

cells usually release energy and

shrink in such circumstances.

Now, Muller and her team have

discovered something else unusual.

They analysed samples of bone

marrow fat and below-skin fat from

people undergoing hip surgery, and

found the bone marrow fat cells

produce a distinctive set of proteins.

This means they have a different

metabolic role to white fat and

should be regarded as a distant

subtype, the researchers conclude.

They propose calling them “yellow

adipocytes”, or yellow fat (bioRxriv,

doi.org/c7bd).

Bone marrow fat should indeed

be regarded as a different type of

fat, says William Cawthorn at the

University of Edinburgh, UK. Some

of his research suggests the benefits

of a calorie-restricted diet may be

linked to a hormone produced by

the cells - although he thinks it is

confusing to give them a new name.

What isn’t clear is why yellow

fat behaves in such an odd way.

It may play such a vital role in the

production of blood cells in bone

marrow that the body can’t afford

to use it as an energy source during

lean times, Muller says. This might

explain why the cells don’t shrink

when we starve. ❚

Strange fat cells in

our bones don’t act

like fat as we know it

Analysis Food production

Is vertical farming the way to a greener life? Crops grown

under lights in racks are said to be environmentally friendly,

but their eco credentials are unclear, finds Adam Vaughan

THE herbs in your future online

supermarket delivery may be

grown not in a field in a distant

country, but in a shed on the

outskirts of a nearby city. Last

week, UK online supermarket

Ocado invested £17 million in

vertical farming, an industry that

advocates say can produce food

in a more environmentally friendly

way. So will the investment allow

Ocado to deliver greener fare?

Ocado has taken a majority

stake in Jones Food, which runs

Europe’s biggest vertical farm on

an industrial estate in Scunthorpe,

UK. It has also invested in a joint

venture with a further two firms

involved in vertical farming: Priva,

based in the Netherlands, and

80 Acres in Ohio.

Vertical farming involves

growing crops indoors under

lights, in racks several metres tall.

The technology expands crop

production upwards and so

requires less land. It also means

that crops can be grown closer

to where they will be consumed.

That partly explains its success

in Asia, with commercial vertical

farming in Japan dating back more

than 15 years.

The sector has a much younger

history in Europe, emerging over

the past five years. In Scunthorpe,

basil and other herbs, watercress

and leafy salad are grown in water

under LED lights on racking that

would collectively cover about

5000 square metres.

“There’s always been an energy

and employee argument which

has probably held back vertical

farming over the past decade,”

says James Lloyd-Jones of Jones

Food. The efficient nature of LEDs

has been key to addressing that,

along with lower-energy lighting

that just emits the blue and

red wavelengths that plants can

use. Fertiliser use – farming’s

traditional big energy burden – is

“phenomenally reduced”, says

Lloyd-Jones. Pesticide use is zero

because few insects make it into

the indoor environment.

The labour-intensive nature of

vertical farming has been tackled

using automation, to a degree,

with just five of the company’s

eight staff running the farm at

any one time. Other firms in the UK

are pursuing similar approaches.

Stewart McGuire of Ocado,

which has pioneered the use of

robots for packing groceries, says

the company wants to increase

automation, be more efficient with

lighting and grow a wider variety

of crops – probably beginning with

tomatoes, cucumbers and berries.

He says issues with outsourcing

food growth to other countries –

“issues around deforestation, or

mega-farm impacts or carbon

emissions” – will favour local

production in vertical farms.

Do the green claims stand up?

Some studies suggest not: one

US researcher has calculated that

the electricity bills associated with

vertical farming may translate

into hefty carbon footprints that

effectively wipe out “food miles”

savings from growing locally.

“I think there’s a lot of hype

about it,” says Tim Lang at City,

University of London. “[Vertical

farms] are more possible, more

feasible because of LEDs, but

they are still energy intensive.” He

thinks conventional greenhouses,

perhaps on city rooftops, are a

better way of bringing food

production closer to demand.

Vertical farming could hold

some environmental benefits,

says Duncan Cameron at the

University of Sheffield, UK, because

it requires much less fertiliser. Food

waste is also “reduced hugely”, he

says, because of the “just-in-time”

nature of indoor farms.

But Cameron says vertical

farming involves huge amounts

of water and electricity. “We

need to be cautious about the

sustainability claims,” he says. ❚

HO

LLY

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/^ JO

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LED lights let

plants grow inside

all year round

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