64 research outputs found
An autonomous chemically fuelled small-molecule motor
Molecular machines are among the most complex of all functional molecules and lie at the heart of nearly every biological process. A number of synthetic small-molecule machines have been developed, including molecular muscles, synthesizers, pumps, walkers, transporters and light-driven and electrically driven rotary motors. However, although biological molecular motors are powered by chemical gradients or the hydrolysis of adenosine triphosphate (ATP), so far there are no synthetic small-molecule motors that can operate autonomously using chemical energy (that is, the components move with net directionality as long as a chemical fuel is present). Here we describe a system in which a small molecular ring (macrocycle) is continuously transported directionally around a cyclic molecular track when powered by irreversible reactions of a chemical fuel, 9-fluorenylmethoxycarbonyl chloride. Key to the design is that the rate of reaction of this fuel with reactive sites on the cyclic track is faster when the macrocycle is far from the reactive site than when it is near to it. We find that a bulky pyridine-based catalyst promotes carbonate-forming reactions that ratchet the displacement of the macrocycle away from the reactive sites on the track. Under reaction conditions where both attachment and cleavage of the 9-fluorenylmethoxycarbonyl groups occur through different processes, and the cleavage reaction occurs at a rate independent of macrocycle location, net directional rotation of the molecular motor continues for as long as unreacted fuel remains. We anticipate that autonomous chemically fuelled molecular motors will find application as engines in molecular nanotechnology.</p
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Gene expression changes in phosphorus deficient potato (Solanum tuberosum L.) leaves and the potential for diagnostic gene expression markers
Background: There are compelling economic and environmental reasons to reduce our reliance on inorganic phosphate (Pi)
fertilisers. Better management of Pi fertiliser applications is one option to improve the efficiency of Pi fertiliser use, whilst
maintaining crop yields. Application rates of Pi fertilisers are traditionally determined from analyses of soil or plant tissues.
Alternatively, diagnostic genes with altered expression under Pi limiting conditions that suggest a physiological
requirement for Pi fertilisation, could be used to manage Pifertiliser applications, and might be more precise than indirect
measurements of soil or tissue samples.
Results: We grew potato (Solanum tuberosum L.) plants hydroponically, under glasshouse conditions, to control their
nutrient status accurately. Samples of total leaf RNA taken periodically after Pi was removed from the nutrient solution were
labelled and hybridised to potato oligonucleotide arrays. A total of 1,659 genes were significantly differentially expressed
following Pi withdrawal. These included genes that encode proteins involved in lipid, protein, and carbohydrate
metabolism, characteristic of Pi deficient leaves and included potential novel roles for genes encoding patatin like proteins
in potatoes. The array data were analysed using a support vector machine algorithm to identify groups of genes that could
predict the Pi status of the crop. These groups of diagnostic genes were tested using field grown potatoes that had either
been fertilised or unfertilised. A group of 200 genes could correctly predict the Pi status of field grown potatoes.
Conclusions: This paper provides a proof-of-concept demonstration for using microarrays and class prediction tools to
predict the Pi status of a field grown potato crop. There is potential to develop this technology for other biotic and abiotic
stresses in field grown crops. Ultimately, a better understanding of crop stresses may improve our management of the crop,
improving the sustainability of agriculture
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