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991.
Weiguo Fang Éverton K.K. Fernandes Donald W. Roberts Michael J. Bidochka Raymond J. St. Leger 《Fungal genetics and biology : FG & B》2010,47(7):602-607
Insect pathogenic fungi including Metarhizium anisopliae offer an environmentally friendly alternative to chemical pesticides. However, their use has been limited by their relatively slow killing speed compared to chemicals and low tolerance to abiotic stresses. We report here on a class 1 laccase (MLAC1) that is involved in both virulence and tolerance to environmental stresses. Mlac1 is expressed during isotropic growth (swelling) but not during polarized growth (e.g., germ tubes and hyphae); Mlac1 is therefore expressed exclusively in the later stages of conidiation and in blastospores when M. anisopliae is living as a saprophyte. During infection processes, Mlac1 is also expressed by appressoria (infection structures) on the cuticle surface and hyphal bodies inside the insect haemocoel. Disrupting Mlac1 reduced virulence to caterpillars because of impaired appressoria and delayed post-infection events. It also produced a yellow-conidia phenotype with increased conidial susceptibility to heat shock (45 °C for 2 h) and UV-B stress. The relationship between M. anisopliae’s pigment-synthesis pathway and its adaptation to diverse natural habitats is discussed. 相似文献
992.
993.
Access management is among the most important conservation actions for grizzly bears in North America. In Alberta, Canada, nearly all grizzly bear mortalities are caused by humans and occur near roads and trails. Consequently, understanding how bears move relative to roads is of crucial importance for grizzly bear conservation. We present the first application of step‐selection functions to model habitat selection and movement of grizzly bears. We then relate this to a step‐length analysis to model the rate of movement through various habitats. Grizzly bears of all sex and age groups were more likely to select steps closer to roads irrespective of traffic volume. Roads are associated with habitats attractive to bears such as forestry cutblocks, and models substituting cutblocks for roads outperformed road models in predicting bear selection during day, dawn, and dusk time periods. Bear step lengths increased near roads and were longest near highly trafficked roads indicating faster movement when near roads. Bear selection of roads was consistent throughout the day; however, time of day had a strong influence over selection of forest structure and terrain variables. At night and dawn, bears selected forests of intermediate age between 40 and 100 yr, and bears selected older forests during the day. At dawn, bears selected steps with higher solar radiation values, whereas, at dusk, bears chose steps that were significantly closer to edges. Because grizzly bears use areas near roads during spring and most human‐caused mortalities occur near roads, access management is required to reduce conflicts between humans and bears. Our results support new conservation guidelines in western North America that encourage the restriction of human access to roads constructed for resource extraction. 相似文献
994.
With the intensive application of carbendazim in greenhouse production of vegetables and the production of medicinal herbs,
there is an increasing need to find a way to remediate carbendazim-contaminated soil. A bacterial stain capable of utilizing
carbendazim as the sole source of carbon and energy was isolated from soil. The isolate was designated CBW and identified
as a member of Pseudomonas sp. based on its colony morphology, 16S rRNA gene sequencing and Biolog analysis. About 87.1 and 99.1% of carbendazim at
concentrations of 1.0 and 10.0 mg l−1 in mineral salts medium were removed by the isolate CBW after incubation for 3 days, respectively. The optimal pH value for
the isolate CBW to degrade carbendazim was 7.0. The degradation rate of carbendazim by the isolate CBW was found to increase
slightly with temperature. According to the metabolites detected and identified in the present study, it was proposed that
carbendazim was first converted to 2-aminobenzimidazole, which was then transformed to 2-hydroxybenzimidazole, 1,2-diaminobenzene,
catechol, and finally to carbon dioxide. The results indicate that the isolate CBW is a new bacterial resource for biodegrading
carbendazim and might be used for bioremediation of sites heavily contaminated by carbendazim and its derivatives. 相似文献
995.
Fang Du Li Zhu Zhong-Ming Qian Xiao-Mei Wu Wing-Ho Yung Ya Ke 《生物化学与生物物理学报:疾病的分子基础》2010,1802(11):1048-1053
It has been demonstrated that hypoxia-inducible factor-1 alpha (HIF-1 alpha) mediates ischemic tolerance induced by hypoxia/ischemia or pharmacological preconditioning. In addition, preconditioning stimuli can be cross-tolerant, safeguarding against other types of injury. We therefore hypothesized HIF-1 alpha might also be associated with ischemic tolerance induced by hyperthermic preconditioning. In the present study, we demonstrated for the first time that 6 h of hyperthermia (38 °C or 40 °C) could induce a characteristic “reactive” morphology and a significant increase in the expression of bystin in astrocytes. We also showed that pre-treatment with 6 h of hyperthermia resulted in a significant increase in cell viability and a remarkable decrease in lactate dehydrogenase (LDH) release and apoptosis development in the astrocytes that were exposed to 24 h of ischemia and a subsequent 24 h of reperfusion. Analysis of mechanisms showed that hyperthermia could lead to a significant increase in HIF-1 alpha expression and also the HIF-1 binding activity in the ischemia/reperfusion astrocytes. The data provide evidence to our hypothesis that the up-regulation of HIF-1 alpha is associated with the protective effects of hyperthermic preconditioning on astrocytes against ischemia/reperfusion injury. 相似文献
996.
Zhengfeng Fang Kang Yao Xiaoling Zhang Shengjun Zhao Zhihong Sun Gang Tian Bing Yu Yan Lin Biquan Zhu Gang Jia Keying Zhang Daiwen Chen De Wu 《Amino acids》2010,39(3):633-640
Sulfur amino acids (SAA), particularly methionine and cysteine, are critical for the gut to maintain its functions including the digestion, absorption and metabolism of nutrients, the immune surveillance of the intestinal epithelial layer and regulation of the mucosal response to foreign antigens. However, the metabolism of SAA in the gut, specifically the transmethylation of methionine, will result in a net release of homocysteine, which is shown to be associated with cardiovascular disease and stroke. Furthermore, the extensive catabolism of dietary methionine by the intestine or by luminal microbes may result in a decrease in nutritional efficiency. Therefore, the regulation of SAA metabolism in the gut is not only nutritionally relevant, but also relevant to the overall health and well-being. The superiority of dl-2-hydroxy-4-methylthiobutyrate to dl-methionine in decreasing homocysteine production, alleviating stress responses, and reducing the first-pass intestinal metabolism of dietary methionine may provide a promising implication for nutritional strategies to manipulate SAA metabolism and thus to improve the nutrition and health status of animals and perhaps humans. 相似文献
997.
Kildare Miranda Douglas A. Pace Roxana Cintron Juliany C. F. Rodrigues Jianmin Fang Alyssa Smith Peter Rohloff Elvis Coelho Felix De Haas Wanderley De Souza Isabelle Coppens L. David Sibley Silvia N. J. Moreno 《Molecular microbiology》2010,76(6):1358-1375
Toxoplasma gondii belongs to the phylum Apicomplexa and is an important cause of congenital disease and infection in immunocompromised patients. Like most apicomplexans, T. gondii possesses several plant‐like features, such as the chloroplast‐like organelle, the apicoplast. We describe and characterize a novel organelle in T. gondii tachyzoites, which is visible by light microscopy and possesses a broad similarity to the plant vacuole. Electron tomography shows the interaction of this vacuole with other organelles. The presence of a plant‐like vacuolar proton pyrophosphatase (TgVP1), a vacuolar proton ATPase, a cathepsin L‐like protease (TgCPL), an aquaporin (TgAQP1), as well as Ca2+/H+ and Na+/H+ exchange activities, supports similarity to the plant vacuole. Biochemical characterization of TgVP1 in enriched fractions shows a functional similarity to the respective plant enzyme. The organelle is a Ca2+ store and appears to have protective effects against salt stress potentially linked to its sodium transport activity. In intracellular parasites, the organelle fragments, with some markers colocalizing with the late endosomal marker, Rab7, suggesting its involvement with the endocytic pathway. Studies on the characterization of this novel organelle will be relevant to the identification of novel targets for chemotherapy against T. gondii and other apicomplexan parasites as well. 相似文献
998.
Li-Xia Cheng Jiang-Jiang Tang Hui Luo Xiao-Ling Jin Fang Dai Jie Yang Yi-Ping Qian Xiu-Zhuang Li Bo Zhou 《Bioorganic & medicinal chemistry letters》2010,20(8):2417-2420
Eight hydroxyl-substituted Schiff bases with the different number and position of hydroxyl group on the two asymmetric aromatic rings (A and B rings) were prepared by the reaction between the corresponding aromatic aldehyde and aniline. Their antioxidant effects against the stable galvinoxyl radical (GO) in ethyl acetate and methanol, and 2,2′-azobis(2-amidinopropane hydrochloride) (AAPH)-induced DNA strand breakage, and their antiproliferative effects on human hepatoma HepG2 cells, were investigated. Structure–activity relationship analysis demonstrates that o-dihydroxyl groups on the aromatic A ring and 4-hydroxyl group attached to the aromatic B ring contribute critically to the antioxidant and antiproliferative activities. 相似文献
999.
He Zhong Jiang Xiao Fang Quan Wei Xi Tian Jiang Miao Hu Peng Cheng Wang Sheng Zhuo Huang Zhong Quan Cheng Wen Juan Liang Jun Zhou Xiao Feng Ma You Xing Zhao 《Bioorganic & medicinal chemistry letters》2010,20(20):6045-6047
Natural inhibitors of fatty acid synthase (FAS) are emerging as potential therapeutic agents to treat cancer and obesity. The bioassay-guided chemical investigation of the hulls of Garcinia mangostana led to the isolation of 13 phenolic compounds (1–13) mainly including xanthone and benzophenone, in which compounds 7, 8, 9, 10, and 11 were isolated from this plant for the first time and compound 9 was a new natural product. These isolates possess strong inhibitory activity of FAS with the IC50 values ranging from 1.24 to 91.07 μM. The study indicates that two types of natural products, xanthones and benzophenones, could be considered as promising FAS inhibitors. 相似文献
1000.