Hailed as the biggest breakthrough in
genetic science this century, CRISPR is
shorthand for a molecular toolkit that allows
scientists to make precise changes to the
genetic code of living organisms. Strictly
speaking, the acronym stands for ‘clustered
regularly interspaced short palindromic
repeats’, a pattern in the DNA of bacteria
first noticed by 1987. For years the role of
this pattern was mysterious, but in the mid-
2000s clues emerged that suggested it was
part of the antivirus defence system of
bacteria. Studies showed bacteria took
sections of a virus’s DNA and built it into
their own genome using an enzyme
codenamed Cas. The resulting CRISPR
sequences then allowed the bacteria to
detect an attack and fight back. But the key
breakthrough came in 2012, when teams in
the US and Europe led by Jennifer Doudna
and Emmanuelle Charpentier showed how
the defence system could be turned into a
‘cut and paste’ tool for editing gene
sequences. However, another US team beat
them to a patent for using the method on
human cells, sparking a legal row over
priority – and last February, the US patent
office ruled against Doudna and
Charpentier. Despite this, they remain
widely credited as the real pioneers of
CRISPR by fellow scientists. RMWHO REALLY DISCOVERED?CRISPR
EMMANUELLE CHARPENTIER AND
JENNIFER DOUDNABROAD INSTITUTEQA
&
PHOTOS: WIKIPEDIA, GETTY X3, ZUMA PRESS/EYEVINEDo trees reduce air pollution levels?
The relationship between trees and air
pollution is a complicated one.
Particulate matter suspended in polluted
air tends to settle onto leaves, and
certain gases including nitrous dioxide
(NO2) are absorbed by leaves’ stomata,
filtering the air and reducing pollution
levels slightly. But trees and other
vegetation also restrict airflow in theirimmediate vicinity, preventing pollution
from being diluted by currents of cleaner
air. In particular, tall trees with thick
canopies planted alongside busy roads
can act like a roof, trapping pockets of
polluted air at ground level. To reliably
improve air quality, city planners need to
give careful consideration to how trees
are placed. AFCHow does
physical exercise
help reduce stress?
Research clearly shows that physical exercise
can reduce stress and anxiety, but it’s less
clear how this occurs. Multiple mechanisms
are likely to be important. Exercise can help
to reduce the body’s response to stress by
boosting serotonin levels in the brain. It
can also give us a sense of achievement
and increase our self-esteem, which can
provide psychological routes by which
to reduce stress. Finally, research
shows that exercise taken in moderate
amounts and at appropriate times
of the day can improve our sleep.
Good sleep quality can help us
to regulate our emotions and
therefore provides another way in
which physical exercise helps to
reduce stress. LV