Since the initial observations in the 1950s a large number of neurotransmitters and hormones have been shown to influence phosphatidylinositol (PI) metabolism in brain and peripheral ganglia (see ref. 3 for review). This has led to the suggestion that PI is part of an intracellular second messenger system for some types of diffusible chemical factors. Consistent with this are recent reports that one of the products of PI turnover (diacylglycerol) stimulates the Ca-dependent phospholipid-dependent protein kinase (kinase C) while a second (inositol trisphosphate) causes the release of calcium from intracellular stores. Thus it is possible that at least some brain neurotransmitters utilize the PI system to produce functional effects that are in addition to and which outlast the very brief physiological responses they elicit. Although it had been anticipated that another class of receptors might inhibit receptor-mediated stimulation of PI breakdown, no clear examples of such effects have been described. We now report that acidic amino acids, which are that acidic amino acids, which are thought to be excitatory neurotransmitters at the majority of brain synapses, strongly inhibit the stimulation of PI metabolism elicited by carbachol, histamine, or by potassium-induced depolarization, without changing the response to noradrenaline. As well as indicating a novel function for the excitatory amino acids, these results suggest that the central nervous system possesses cell-cell interactions of a previously unsuspected type.

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The application of electrical nanoprobes to measure and characterise nanomaterials has become widely spread. However, the formation of quality electrical contacts using metallic probes on nanostructures has not been directly assessed. We investigate here the contact electrical behaviour of non-lithographically formed contacts to ZnO nanowires and develop a method to reproducibly form contacts. The contacting method NWs relies on an electrical feedback to determine the point of contact, ensuring minimal compressive strain at the contact. This developed method is compared with the standard tip deflection contacting technique and shows a significant improvement to reproducibility. The effect of excessive compressive strain at the contact was investigated, with a change from rectifying to ohmic I-V behaviour observed as compressive strain at the contact is increased, leading to irreversible changes to the electrical properties of the NW. The potential effect of current annealing the nanowire and contacts was considered and shown not to be a major contributing factor to the change in I-V behaviour. This work provides an ideal method for forming reproducible non-lithographic nanocontacts to a multitude of nanomaterials.

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Illustrations are a fundamental feature in children's picture books and the evidence suggests that they are more than simply window dressing to make books look more attractive.