2019-06-22_New_Scientist

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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. ❚

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LED lights let
plants grow inside
all year round

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