<Emphasis Type="Italic">N</Emphasis>-acyl-homoserine lactone-mediated quorum sensing blockage,a novel strategy for attenuating pathogenicity of Gram-negative bacterial plant pathogens

Quorum sensing is a bacterial communication mechanism by which bacteria sense their own population size and couple specific gene expression to cell density. In Gram-negative bacteria, the most commonly used quorum sensing signals are N-acyl homoserine lactones (AHLs). It is now apparent that many pathogenic bacteria employ quorum sensing to control premature expression of virulence factors. This control is thought to decrease the likelihood that the plant host would detect the pathogens presence and activate its defense system. Novel strategies that target bacterial quorum sensing systems in order to control plant bacterial diseases are discussed.     

Risk factors for outbreaks of infectious salmon anemia in farmed Atlantic salmon, Salmo salar

Infectious salmon anemia (ISA) is a viral disease occurring in farmed Atlantic salmon (Salmo salar) that is characterized by lethargy, anorexia, anemia and death. To control the disease in New Brunswick, Canada, 7.5 million fish from outbreak cages have been destroyed since 1997. Despite changes made by farmers, 2002 was the worst year ever for ISA losses in the region.

We evaluated the associations between potential risk factors and ISA outbreaks in the Atlantic-salmon sites in New Brunswick. This was a multilevel study in which the site-level design was a retrospective cohort study while the cage-level design was a modified case-cohort study. The questionnaire was divided into site-level questions, cage-level questions and hatchery information.

The important factors identified by this study can be categorized as environmental, farmer controlled or industry controlled according to the capacity to change or eliminate them. Environmental risk factors such as increasing the depth of the net (if nets were ≤9 m, odds ratio (OR) = 3.34) and decreasing the depth of water underneath the net (if depth of water underneath the net >3 m, OR = 3.34) are for the most part dictated by site location. Wild pollock (Pollachius virens) in the cage reflects the number of wild pollock that live in the site location. If there were ≥1000 pollock in the cage, the odds of disease in the cage increased 4.43-fold. Risk factors that are under farm control include increasing the number of times that the salmon are treated for sea lice (OR = 3.31 if lice treatments are ≤2 times), transferring small smolts into seawater (OR = 2.40 if smolts weighed >99 g) and improving on the adaptation of smolts to seawater to reduce post-transfer mortalities (OR = 4.52 if there was at least one cage with post-transfer mortalities >5%). The industry-controlled factors need to be addressed by the industry as a whole. Organizing boat travel to minimize the time and frequency of boats travelling to or by sites currently is being reviewed. This will be extremely important because the OR = 9.43 if processing boats travel within 1 km of the site and the OR = 4.03 if the site has dry feed delivered by the feed company. Because the hazard ratio increased stepwise from 1 if the nearest neighbor with ISA was ≥5 km up to 5.5 if the nearest site with ISA was within 0.5 km, increasing the distance between sites might be necessary for effective control.     

Effects of NF-κB "decoy" oligodeoxynucleotides on TNF-α and IL-6 expression in LPS-induced mouse macrophages

AIM: To study the effect of NF-κB "decoy" oligodeoxynucleotides on TNF-α and IL-6 expression in LPS-induced mouse macrophages. METHODS: Mouse macrophage cell line J774.1 cells were cultured with LPS and liposome-mediated oligodeoxynucleotides, and the levels of TNF-α and IL-6 measured in the different culture supernatant by enzyme linked immunosorbent assay. RNA was extracted from macrophages, and the mRNA expression of TNF-α and IL-6 in macrophages was observed by RT-PCR. RESULTS: NF-κB "decoy" oligodeoxynucleotides decreased the expression of TNF-α and IL-6 in LPS-induced macrophages and inhibited generation of TNF-α and IL-6. The level of TNF-α and IL-6 did not change in control group. CONCLUSIONS: NF-κB "decoy" oligodeoxynucleotides inhibit the expression of TNF-α and IL-6 in LPS-induced macrophages, which is probably due to the specific inhibition of activated NF-κB binding sites .     

Environmental factors influencing sporocarp formation in <Emphasis Type="Italic">Typhula ishikariensis</Emphasis>

Environmental factors influencing sporocarp formation in Typhula ishikariensis were studied under controlled conditions. Sporocarp formation in T. ishikariensis was divided into two stages: stipe elongation from the sclerotium and fertile head development at the tip of the stipe. Factors required for each stage differed. At the stipe elongation stage, low temperature (10°/5°C; day/night) and high humidity were important, but light was not required. In contrast, at the fertile head stage, light and moderate day length (8h/day) were essential. Fertile heads developed at 46µEm^–2s^–1; and high intensity (137µEm^–2s^–1) did not suppress development. Moreover, adding unsterilized soil to the sea sand medium accelerated sporocarp formation. These findings imply that the sclerotium of T. ishikariensis recognizes several physical factors for sporocarp formation. Sporocarps of T. ishikariensis developed within 4 weeks after incubation under optimal conditions. The sporocarp produced basidiospores, and differential mating incompatibility was confirmed among monokaryons derived from basidiospores produced under artificial conditions. This method should be useful for obtaining monokaryons for genetic studies of T. ishikariensis.     

Gene expressions of canine angiopoietin-1 and -2 in normal tissues and spontaneous tumours

The angiopoietin (Ang) family of proteins are central to the regulation of angiogenesis. The purposes of this study were to determine cDNA sequences of canine Ang-1 and Ang-2 and investigate their expressions in normal tissues and spontaneous tumours. The cDNA sequences of canine Ang-1 and Ang-2 were 1,494 and 1,488 bp, and the deduced amino acid sequences were 497 and 495 residues, respectively. The cDNA sequences of canine Ang-1 and Ang-2 showed high homology with those of the other mammalian species. Canine Ang-1 and Ang-2 mRNA were detectable in all 22 normal tissues and spontaneous tumours. Higher mRNA expression level of canine Ang-2 was demonstrated in mammary simple carcinomas, haemangiosarcoma and hepatocellular carcinoma in comparison with normal tissues.     

Evaluation of single and double centrifugation tube methods for concentrating equine platelets

The aim of this study was to evaluate single and double centrifugation tube methods for concentrating equine platelets. Whole blood samples were collected from clinically normal horses and processed by use of single and double centrifugation tube methods to obtain four platelet concentrates (PCs): PC-A, PC-B, PC-C, and PC-D, which were analyzed using a flow cytometry hematology system for hemogram and additional platelet parameters (mean platelet volume, platelet distribution width, mean platelet component concentration, mean platelet component distribution width). Concentrations of transforming growth factor beta 1 (TGF-beta(1)) were determined in all the samples. Platelet concentrations for PC-A, PC-B, PC-C, and PC-D were 45%, 44%, 71%, and 21% higher, respectively, compared to the same values for citrated whole blood samples. TGF-beta(1) concentrations for PC-A, PC-B, PC-C, and PC-D were 38%, 44%, 44%, and 37% higher, respectively, compared to citrated whole blood sample values. In conclusion, the single and double centrifugation tube methods are reliable methods for concentrating equine platelets and for obtaining potentially therapeutic TGF-beta(1) levels.     

Effect of antioxidant supplementation on free radical scavenging system and immune response in lindane treated scabies patients

The scabicide, lindane induces oxidative stress and immunological alterations. The present study was undertaken to assess the ameliorative effects of antioxidant supplementation in lindane treated scabies patients. Scabies patients were treated with either 1% lindane or 1% lindane along with antioxidant (Lycored or Vitamin-E). Oxidative stress and immunological parameters were evaluated in blood samples and compared with healthy controls. Lindane caused a significant increase in malonedialdehyde (MDA) levels and decrease in reduced glutathione (GSH) and ferric reducing ability of plasma (FRAP), which was attenuated by anti-oxidant therapy. The IL-1α levels were significantly enhanced in scabies patients per se and remained unaffected after lindane/anti-oxidant treatment. The TNF-α and nitroblue tetrazolium (NBT) reduction levels were not significantly different in all the groups. Topical application of lindane induces significant free radical generation and may cause immunological alterations which can be reversed by antioxidant therapy.     

香梨上山楂叶螨自然种群连续世代生命表分析

本研究对香梨园各世代山楂叶螨种群生命表的趋势动态指数I、控制指数(EIPC)、关键虫期、关键因子、关键因子与种群密度关系进行分析,建立最优回归预测方程,以评价影响山楂叶螨种群发展的各因子的作用。结果表明,山楂叶螨种群11代的种群趋势指数分别为0.98、8.90、3.74、0.87、0.41、0.22、0.02、1.00、2.09、2.23、2.97。"捕食及其他"和"自然死亡"因子是影响山楂叶螨种群各世代数量动态的重要因子。幼螨期是山楂叶螨的关键虫期,在幼螨期的"捕食及其他"因子是关键因子,关键因子是山楂叶螨种群变化的迟滞密度制约因子。     

山东泰安地区小麦禾谷孢囊线虫幼虫孵化特性初步研究

为大量获得研究所需的小麦禾谷孢囊线虫2龄幼虫,在室内离体条件下研究了预处理条件、孵化温度、低温预处理时间以及田间采样时期对山东泰安地区小麦禾谷孢囊线虫幼虫孵出量的影响.结果表明:5℃低温预处理条件下,孢囊浸水处理有利于幼虫孵出;低温预处理后,孵化温度为15℃处理的2龄幼虫孵出率高于20℃处理的孵出率;低温预处理时间为8周的2龄幼虫孵出率最高;6月和8月田间采集的孢囊幼虫孵出率显著高于7月和9月,其中8月采集的孢囊幼虫孵出率最高,为最佳采集时间.     

内蒙古自治区沙尘暴的分布特征及其影响因素分析

根据国家气象局的48个基本气象站沙尘暴及相关资料分析得出,影响内蒙古自治区沙尘暴的因素,不仅有风速、大风持续时间与频率等动力因素,亦有物质组成(颗粒)、植被盖度、土壤含水量等下垫面因素。沙尘暴并非单一天气现象,而是天地碰撞的产物,人可通过干扰"地"而影响沙尘暴。文中提出一些观点可为研究区域沙尘暴成因,科学制定防治措施提供参考。