Detecting small changes and additional peptides in the canine parvovirus capsid structure

Parvovirus capsids are assembled from multiple forms of a single protein and are quite stable structurally. However, in order to infect cells, conformational plasticity of the capsid is required and this likely involves the exposure of structures that are buried within the structural models. The presence of functional asymmetry in the otherwise icosahedral capsid has also been proposed. Here we examined the protein composition of canine parvovirus capsids and evaluated their structural variation and permeability by protease sensitivity, spectrofluorometry, and negative staining electron microscopy. Additional protein forms identified included an apparent smaller variant of the virus protein 1 (VP1) and a small proportion of a cleaved form of VP2. Only a small percentage of the proteins in intact capsids were cleaved by any of the proteases tested. The capsid susceptibility to proteolysis varied with temperature but new cleavages were not revealed. No global change in the capsid structure was observed by analysis of Trp fluorescence when capsids were heated between 40 degrees C and 60 degrees C. However, increased polarity of empty capsids was indicated by bis-ANS binding, something not seen for DNA-containing capsids. Removal of calcium with EGTA or exposure to pHs as low as 5.0 had little effect on the structure, but at pH 4.0 changes were revealed by proteinase K digestion. Exposure of viral DNA to the external environment started above 50 degrees C. Some negative stains showed increased permeability of empty capsids at higher temperatures, but no effects were seen after EGTA treatment.     

Communication during aggressive interactions with particular reference to variation in choice of behaviour

Communication during aggressive interactions is discussed and defined primarily on the basis of functional considerations. A distinction is made between communication due to choice of action and communication due to performance of a given choice of action. Most attention is directed to choice of behaviour. Two models are developed to show that there are no arguments of general validity against communication through choice of behaviour or signalling as has been claimed. The first model is built on variation in fighting ability only and shows that choice of signal can carry information both about intentions (use of local strategy) and fighting ability. The second model which is based on the war of attrition with random rewards instead considers variation in subjective resource value. It shows that signalling of local strategy can be stable. It is concluded that evolutionary stability of communication through choice of behaviour is due to variation among animals in the utility of showing different behaviour patterns whereas communication by performance is due to a not easily removed relationship between the performance of a certain behaviour pattern and the factor communicated.     

Engineered multidomain cysteine protease inhibitors yield resistance against western flower thrips (Frankliniella occidentalis) in greenhouse trials

Western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), cause very large economic damage on a variety of field and greenhouse crops. In this study, plant resistance against thrips was introduced into transgenic potato plants through the expression of novel, custom-made, multidomain protease inhibitors. Representative classes of inhibitors of cysteine and aspartic proteases [kininogen domain 3 (K), stefin A (A), cystatin C (C), potato cystatin (P) and equistatin (EIM)] were fused into reading frames consisting of four (K-A-C-P) to five (EIM-K-A-C-P) proteins, and were shown to fold into functional inhibitors in the yeast Pichia pastoris. The multidomain proteins were expressed in potato and found to be more resistant to degradation by plant proteases than the individual domains. In a time span of 14-16 days, transgenic potato plants expressing EIMKACP and KACP at a similar concentration reduced the number of larvae and adults to less than 20% of the control. Leaf damage on protected plants was minimal. Engineered multidomain cysteine protease inhibitors thus provide a novel way of controlling western flower thrips in greenhouse and field crops, and open up possibilities for novel insect resistance applications in transgenic crops.     

Specific cysteine protease inhibitors act as deterrents of western flower thrips, Frankliniella occidentalis (Pergande), in transgenic potato

In this study, the effects of the accumulation of cysteine protease inhibitors on the food preferences of adult female western flower thrips, Frankliniella occidentalis (Pergande), were investigated. Representative members of the cystatin and thyropin gene families (stefin A, cystatin C, kininogen domain 3 and equistatin) were expressed in potato (Solanum tuberosum) cv. Impala, Kondor and Line V plants. In choice assays, a strong time- and concentration-dependent deterrence from plants expressing stefin A and equistatin was observed. Cystatin C and kininogen domain 3 were not found to be active. All tested inhibitors were equally or more active than stefin A at inhibiting the proteolytic activity of thrips, but, in contrast with stefin A, they were all expressed in potato as partially degraded proteins. The resistance of cysteine protease inhibitors against degradation in planta by endogenous plant proteases may therefore be relevant in explaining the observed differences in the deterrence of thrips. The results demonstrate that, when given a choice, western flower thrips will select plants with low levels of certain cysteine protease inhibitors. The novel implications of the defensive role of plant cysteine protease inhibitors as both deterrents and antimetabolic proteins are discussed.     

Non-invasive evaluation of ventricular refractoriness and its dispersion during ventricular fibrillation in patients with implantable cardioverter defibrillator

Background

Despite improvements in the safety and efficacy of endovascular procedures, considerable morbidity may still be attributed to vasospasm. Vasospasm has proven amenable to pharmacological intervention such as nitrates, intravenous calcium channel blockers (CCBs), and intra-arterial papaverine, particularly in small vessels. However, few studies have focused on medium to large vessel spasm. Here we report the use of an intra-arterial CCB, verapamil, to treat flow-limiting mechanically-induced spasm of the common carotid artery (CCA) in a primate. We believe this to be the first such report of its kind.

Case presentation

As part of a study assessing the placement feasibility and safety of a catheter capable of delivering intra-arterial cerebroprotective therapy, a female 16 kg baboon prophylaxed with intravenous nitroglycerin underwent transfemoral CCA catheterization with a metallic 6-Fr catheter without signs of acute spasm. The protocol dictated that the catheter remain in the CCA for 12 hours. Upon completion of the protocol, arteriography revealed a marked decrease in CCA size (mean cross-sectional area reduction = 31.6 ± 1.9%) localized along the catheter length. Intra-arterial verapamil (2 mg/2cc) was injected and arteriography was performed 10 minutes later. Image analysis at 6 points along the CCA revealed a 21.0 ± 1.7% mean increase in vessel diameter along the length of the catheter corresponding to a 46.7 ± 4.0% mean increase in cross-sectional area. Mean systemic blood pressure did not deviate more than 10 mm Hg during the procedure.

Conclusions

Intraluminal CCBs like verapamil may constitute an effective endovascular treatment for mechanically-induced vasospasm in medium to large-sized vessels such as the CCA.     

System expansion and allocation in life cycle assessment of milk and beef production

Background, Goal and Scope  System expansion is a method used to avoid co-product allocation. Up to this point in time it has seldom been used in LCA studies of food products, although food production systems often are characterised by closely interlinked sub-systems. One of the most important allocation problems that occurs in LCAs of agricultural products is the question of how to handle the co-product beef from milk production since almost half of the beef production in the EU is derived from co-products from the dairy sector. The purpose of this paper is to compare different methods of handling co-products when dividing the environmental burden of the milk production system between milk and the co-products meat and surplus calves. Main Features  This article presents results from an LCA of organic milk production in which different methods of handling the co-products are examined. The comparison of different methods of co-product handling is based on a Swedish LCA case study of milk production where economic allocation between milk and meat was initially used. Allocation of the co-products meat and surplus calves was avoided by expanding the milk system. LCA data were collected from another case study where the alternative way of producing meat was analysed, i.e. using a beef cow that produces one calf per annum to be raised for one and a half year. The LCA of beef production was included in the milk system. A discussion is conducted focussing on the importance of modelling and analysing milk and beef production in an integrated way when foreseeing and planning the environmental consequences of manipulating milk and beef production systems. Results  This study shows that economic allocation between milk and beef favours the product beef. When system expansion is performed, the environmental benefits of milk production due to its co-products of surplus calves and meat become obvious. This is especially connected to the impact categories that describe the potential environmental burden of biogenic emissions such as methane and ammonia and nitrogen losses due to land use and its fertilising. The reason for this is that beef production in combination with milk can be carried out with fewer animals than in sole beef production systems. Conclusion, Recommendation and Perspective  Milk and beef production systems are closely connected. Changes in milk production systems will cause alterations in beef production systems. It is concluded that in prospective LCA studies, system expansion should be performed to obtain adequate information of the environmental consequences of manipulating production systems that are interlinked to each other.