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1.
In this paper, we describe an automated system for distributingupdates to the GenBank nucleic acid sequence database, usingthe Usenet news system as the underlying transport mechanism.Our system allows new loci to be distributed as soon as thesequences are available, over existing networks, using existingUsenet software and infrastructure currently available on awide range of computer systems.  相似文献   
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1. 1. The effect of stimulation of adenylate cyclase by pancreozymin-C-octapeptide on the cyclic AMP level of rat pancreatic fragments has been investigated.
2. 2. In normal Krebs-Ringer bicarbonate medium pancreozymin-C-octapeptide causes a slight increase in pancreatic cyclic AMP level; this increase can be considerably enhanced by incubation in a calcium-free incubation medium.
3. 3. The dose-responce curve for pancreazymin-C-octapeptide in calcium-free medium is shifted to lower peptide concentrations, compared to the curve in normal Krebs-Ringer bicarbonate medium.
4. 4. The maximal stimulatory effect of pancreozymin-C-octapeptide id obtained at a 1-methyl-3-isobutylxanthine concentration of 10 mM.
5. 5. It suffices to lower the Ca2+-concentration of the medium from 2.5 to 1.5 mM to get the maximal increase in cyclic AMP content under influence of pancreozymin-C-octapeptide.
6. 6. It is concluded that extracellular calcium antagonizes the stimulation of adenylate cyclase by pancreozymin-C-octapeptide. This suggest that a low cytoplasmic Ca2+-concentration is required for the maximal response of acinar cell adenylate cyclase to pancreozymin.
Keywords: cyclic AMP formation; Ca2+; Pancreozymin-C-octapeptide; Adeny; ate cyclase; (Rat pancreas)  相似文献   
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Vegetation community composition and the above- and below-ground invertebrate communities are linked intrinsically, though few studies have assessed the impact of non-native plants on both these parts of the community together. We evaluated the differences in the above- (foliage- and ground-dwelling) and below-ground invertebrate communities in nine uninvaded plots and nine plots invaded by the annual invasive species Impatiens glandulifera, in the UK during 2007 and 2008. Over 139,000 invertebrates were identified into distinct taxa and categorised into functional feeding groups. The impact of I. glandulifera on the vegetation and invertebrate community composition was evaluated using multivariate statistics including principal response curves (PRC) and redundancy analysis (RDA). In the foliage-dwelling community, all functional feeding groups were less abundant in the invaded plots, and the species richness of Coleoptera and Heteroptera was significantly reduced. In the ground-dwelling community, herbivores, detritivores, and predators were all significantly less abundant in the invaded plots. In contrast, these functional groups in the below-ground community appeared to be largely unaffected, and even positively associated with the presence of I. glandulifera. Although the cover of I. glandulifera decreased in the invaded plots in the second year of the study, only the below-ground invertebrate community showed a significant response. These results indicate that the above- and below-ground invertebrate communities respond differently to the presence of I. glandulifera, and these community shifts can potentially lead to a habitat less biologically diverse than surrounding native communities; which could have negative impacts on higher trophic levels and ecosystem functioning.  相似文献   
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This study focuses on one particular layer of the pollen wall, which develops below the endexine in the free microspore stage and prior to the initiation of the intine. This membranous-granular layer (MGL) has been described by different terms in the literature and has often been interpreted either as part of the endexine, or the intine. During ontogeny, however, the granular material shows a development that is clearly distinct, both in timing and mode of formation, from the endexine as well as the intine. Its chemical composition is also characteristic; the MGL resists acetolysis. Our ontogenetic observations from four dicot and one monocot species are used to illustrate the systematically widespread occurrence of this wall layer, its ultrastructure and histochemistry, and its comparable nature throughout angiosperms.  相似文献   
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The pollen grain morphology of 30 species of 27 genera from the four subfamilies of the Cyperaceae have been studied with LM and SEM. Several methods were tested in order to find the optimal treatment for the delicate Cyperaceae pollen grains. For LM, treatment with wetting agent Agepon and KOH yielded the best results, while critical point drying (CPD) after fixation with alcohol proved to be the best method for studying pollen grains of Cyperaceae with SEM. Our results show that the Mapanioideae have a pollen grain type (only one distal ulcus) clearly different from the other Cyperaceae. Representatives of the examined Sclerioideae and Caricoideae show a similar pollen grain type (mostly one distal ulcus and three lateral pores) while in the Cyperoideae different pollen grain types are found.  相似文献   
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Quantitative data play an important role in palynological research. With the advent of digital imaging in light and electron microscopy, palynologists now have the opportunity to perform measurements faster and more precisely than ever before. Several image analysis software packages already exist for these tasks, but they are often expensive, difficult to use or not adapted to the specific needs of palynologists. After studying the daily workflow of a palynologist, we designed CARNOY, an image analysis application written from the ground up for use in palynology and morphology. CARNOY offers an easy-to-use interface and several features to make measuring easier and faster. The program can export measurements to almost every other software package for further analysis and is available for free on the Internet.  相似文献   
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Plastics have become ubiquitous in both their adoption as materials and as environmental contaminants. Widespread pollution of these versatile, man-made and largely petroleum-derived polymers has resulted from their long-term mass production, inappropriate disposal and inadequate end of life management. Polyethylene (PE) is at the forefront of this problem, accounting for one-third of plastic demand in Europe in part due to its extensive use in packaging. Current recycling and incineration processes do not represent sustainable solutions to tackle plastic waste, especially once it becomes littered, and the development of new waste-management and remediation technologies are needed. Mycoremediation (fungal-based biodegradation) of PE has been the topic of several studies over the last two decades. The utility of these studies is limited by an inconclusive definition of biodegradation and a lack of knowledge regarding the biological systems responsible. This review highlights relevant features of fungi as potential bioremediation agents, before discussing the evidence for fungal biodegradation of both high- and low-density PE. An up-to-date perspective on mycoremediation as a future solution to PE waste is provided.  相似文献   
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A novel and patented procedure is described for the sonochemical fabrication of a new class of microelectrode array based sensor with electrode element populations of up to 2 x 10(5) cm(-2). For some years it has been accepted that microelectrode arrays offer an attractive route for lowering minimum limits of detection and imparting stir (convectional mass transport) independence to sensor responses; despite this no commercial biosensors, to date, have employed microelectrode arrays, largely due to the cost of conventional fabrication routes that have not proved commercially viable for disposable devices. Biosensors formed by our sonochemical approach offer unrivalled sensitivity and impart stir independence to sensor responses. This format lends itself for mass fabrication due to the simplicity and inexpensiveness of the approach; in the first instance impedimetric and amperometric sensors are reported for glucose as model systems. Sensors already developed for ethanol, oxalate and a number of pesticide determinations will be reported in subsequent publications.  相似文献   
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