In situ analysis of pH gradients in mosquito larvae using non-invasive, self-referencing, pH-sensitive microelectrodes

The alkaline environment, pH approximately 11, in the anterior midgut lumen of mosquito larvae is essential for normal nutrition and development. The mechanism of alkalization is, however, unknown. Although evidence from immunohistochemistry, electron microscopy and electrophysiology suggests that a V-ATPase is present in the basal membranes of the epithelial cells, its physiological role in the alkalization process has not been demonstrated. To investigate a possible role of the V-ATPase in lumen alkalization, pH gradients emanating from the hemolymph side of the midgut in semi-intact mosquito larvae were measured using non-invasive, self-referencing, ion-selective microelectrodes (SERIS). Large H+ concentration gradients, with highest concentrations close to the basal membrane (outward [H+] gradients), were found in the anterior midgut, whereas much smaller gradients, with concentrations lowest close to this membrane (inward [H+] gradients), were found in the gastric caeca and posterior midgut. Similar region-specific pH gradients, with consistent anterior-to-posterior profiles, were observed in individuals of two Aedes species, Aedes aegypti from semi-tropical Florida and Aedes canadensis from north-temperate Massachusetts. The gradients remained in a steady state for up to 6 h, the maximum duration of the recordings. Bafilomycin A1 (10(-5), 10(-7 )mol x l(-1)) on the hemolymph side greatly diminished the [H+] gradients in the anterior midgut but had no effect on the gradients in the gastric caecum and posterior midgut. These physiological data are consistent with the previous findings noted above. Together, they support the hypothesis that a basal, electrogenic H+ V-ATPase energizes luminal alkalization in the anterior midgut of larval mosquitoes

Comprehensive planning theory and the urban renewal program in Canada

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Haemodynamic response to laryngoscopy with and without tracheal intubation

IntroductionTracheal intubation is accompanied by an increased blood pressure and heart rate. The aim of this study was to find the most important source of this haemodynamic response, namely laryngoscopy or intubation.MethodA standard induction technique was used for all patients. Eighty patients were randomly allocated to one of two groups, one group to undergo laryngoscopy followed by intubation (Group I), and the other laryngoscopy only of duration similar to intubation (Group L). Blood pressure and heart rate were recorded in the ward, before induction of anaesthesia and one, two, three, and four minutes after instrumentation.ResultsThe instrumentation times did not differ significantly (p = 0.20). Over time mean arterial pressures were significantly higher in Group I than in Group L (p = 0.038). Over time the ratios of mean blood pressure and heart rate relative to the preoperative heart rate were significantly greater in Group I than in Group L (p < 0.01).ConclusionBlood pressures and heart rates were significantly greater after laryngoscopy followed by intubation than after laryngoscopy of the same duration not followed by intubation. The induction technique, consisting of lignocaine, alfentanil, and propofol, may have attenuated expected increases in blood pressure but not increases in heart rate after intubation

Postgerminative growth and lipid catabolism in oilseeds lacking the glyoxylate cycle

The glyoxylate cycle is regarded as essential for postgerminative growth and seedling establishment in oilseed plants. We have identified two allelic Arabidopsis mutants, icl-1 and icl-2, which lack the glyoxylate cycle because of the absence of the key enzyme isocitrate lyase. These mutants demonstrate that the glyoxylate cycle is not essential for germination. Furthermore, photosynthesis can compensate for the absence of the glyoxylate cycle during postgerminative growth, and only when light intensity or day length is decreased does seedling establishment become compromised. The provision of exogenous sugars can overcome this growth deficiency. The icl mutants also demonstrate that the glyoxylate cycle is important for seedling survival and recovery after prolonged dark conditions that approximate growth in nature. Surprisingly, despite their inability to catalyze the net conversion of acetate to carbohydrate, mutant seedlings are able to break down storage lipids. Results suggest that lipids can be used as a source of carbon for respiration in germinating oilseeds and that products of fatty acid catabolism can pass from the peroxisome to the mitochondrion independently of the glyoxylate cycle. However, an additional anaplerotic source of carbon is required for lipid breakdown and seedling establishment. This source can be provided by the glyoxylate cycle or, in its absence, by exogenous sucrose or photosynthesis

Printed electronics as prepared by inkjet printing

Inkjet printing has been used to produce a range of printed electronic devices, such as solar panels, sensors, and transistors. This article discusses inkjet printing and its employment in the field of printed electronics. First, printing as a field is introduced before focusing on inkjet printing. The materials that can be employed as inks are then introduced, leading to an overview of wetting, which explains the influences that determine print morphology. The article considers how the printing parameters can affect device performance and how one can account for these influences. The article concludes with a discussion on adhesion. The aim is to illustrate that the factors chosen in the fabrication process, such as dot spacing and sintering conditions, will influence the performance of the device

Neutrino Detection using Lead Perchlorate

We discuss the possibility of using lead perchlorate as a neutrino detector. The primary neutrino interactions are given along with some relevant properties of the material.Comment: 2 pages, 2 figures, TAUP-99, TEX fil

A flexible model for dimensioning mixed service 3G wireless networks

In this paper we present an approximate closed form solution for dimensioning mixed service 3G wireless networks for defined service and quality constraints. Both web-browsing services alone, as well as a mixture of web and circuit voice services are considered. Dimensioning is achieved through knowledge of the distribution of the latency delay experienced by end users of the 3G network. The parameters defining the distribution are shown to be dependent on a range of network and service parameters. This allows the dimensioning of 3G wireless networks under a wide range of quality and service conditions