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be converted to a reduced (or ¡®fixed¡¯) state to be useful for higher plants
and animals. Precipitation often contains substantial quantities of ammo-
nium and nitrate, thought to result from nitrogen fixation by lightning and
other atmospheric electric phenomena.
Nitrogen is present in all living organisms, in proteins, nucleic acids, and
other molecules. It typically makes up around 4% of the dry weight of
plant matter, and around 3% of the weight of the human body. It is a large
component of animal waste (for example, guano), usually in the form of
urea, uric acid, ammonium compounds, and derivatives of these nitrog-
enous products, which are essential nutrients for all plants that cannot fix
atmospheric nitrogen. (source:
The ¡°Impossible¡± Is Now Possible
New tools enable real-time monitoring of nitrogen absorption in plants
One Night of Queen
arrives... Pg 4
Botanical Gardens
Open... Pg 13
The Sandhill Crane
Days... Pg 14
Goodness for the
heart... Pg 7
Nitrogen-tracking tools for better crops
and less pollution
February 18, 2014, Stanford, CA: As every gardener
knows, nitrogen is crucial for a plant¡¯s growth. But
nitrogen absorption is inefficient.
This means that on the scale of food crops, adding
significant levels of nitrogen to the soil through fer-
tilizer presents a number of problems, particularly
river and groundwater pollution.
As a result, finding a way to improve nitrogen up-
take in agricultural products could improve yields
and decrease risks to environmental and human
Nitrogen is primarily taken up from the soil by the
roots and assimilated by the plant to become part of
DNA, proteins, and many other compounds.
Uptake is controlled by a number of factors, includ-
ing availability, demand, and the plant¡¯s energy
status, however there is much about the transport
proteins involved in the process that isn¡¯t under-
New work from Carnegie¡¯s Cheng-Hsun Ho and
Wolf Frommer developed tools that can help sci-
entists observe the nitrogen-uptake process in real
time and could lead to developments that improve
agriculture and the environment. Details of the
work will be published by eLife on March 11 and is
2014 March #5-2
already available online.
Frommer had previously developed technology to spy on transport protein
activity by using fluorescent tags in a cell¡¯s DNA to monitor the structural
rearrangements that a transporter undergoes as it moves its target molecule.
They tailored this technology to five nitrogen transport targets to monitor the
nitrogen uptake and assimilation process. ¡°We engineered these sensors to
monitor the activity and regulation of suspected nitrogen transporters in liv-
ing plant roots, which otherwise are impossible to study,¡± Frommer said.
¡°This suite of tools will vastly improve our understanding of the nitrogen-
uptake process and will help to develop increased crop yields and decrease
fertilizer-caused pollution.¡±
Their method is applicable to any transporter from
any organism, thereby enabling the otherwise
exceptionally difficult analysis of the transport pro-
cesses in the tissues of plants and animals.
The NiTrac sensor developed by Cheng Hsun Ho
and Wolf Frommer of the Carnegie Institution will
enable non-invasive real-time monitoring of nitro-
gen acquisition in action in plant roots, providing
a new tool set that can be used to improve nitrogen
efficiency. The novel sensor technology is widely
applicable and useful also for cancer and neurobi-
ology. Credit: Cheng Hsun Ho and Wolf Frommer.
¡°This suite of tools
will vastly improve our
understanding of the
nitrogen-uptake process
and will help to develop
increased crop yields and
decrease fertilizer-caused
pollution.¡± - Wolf Frommer,
Carnegie Institution
Science Foundation which can be found at:
What is Nitrogen?
Nitrogen, symbol N, is the chemical element of
atomic number seven, and is an essential building
block of amino and nucleic acids, essential to life
on Earth.
Elemental nitrogen in the atmosphere cannot be
used directly by either plants or animals, and must
The novel
sensor tech-
nology is
widely ap-
plicable and
useful also
for cancer
and neuro-
This work
was funded
by the Na-