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排序方式: 共有1619条查询结果,搜索用时 31 毫秒
941.
Florie Desriac Abderrafek El Harras Matthieu Simon Arnaud Bondon Benjamin Brillet Patrick Le Chevalier Martine Pugnire Patrice Got Delphine Destoumieux-Garzn Yannick Fleury 《Marine drugs》2020,18(12)
Discovery after discovery, host-associated microbiota reveal a growing list of positive effects on host homeostasis by contributing to host nutrition, improving hosts’ immune systems and protecting hosts against pathogens. In that context, a collection of oyster associated bacteria producing antibacterial compounds have been established to evaluate their role in non-host-derived immunity. Here, we described alterins; potent anti-Gram negative compounds produced by Pseudoalteromonas hCg-6 and hCg-42 isolated from different healthy oyster hemolymph. The strains hCg-6 and hCg-42 produce a set of at least seven antibacterial compounds, ranging from 926 to 982 Da structurally characterized as cyclolipopeptides (CLPs). Alterins share the same cationic heptapeptidic cycle connected via an amido bond to different hydrophobic hydrocarbon tails. Their MICs disclosed a potent antibacterial activity directed against Gram-negative bacteria including oyster and human pathogens that may confer a beneficial defense mechanism to the host but also represents an untapped source of new antibiotics. The alterins’ mechanisms of action have been deciphered: after binding to lipopolysaccharides (LPS), alterins provoke a membrane depolarization and permeabilization leading to bacterial lysis. As hCg-6 and hCg-42 produced a set of natural derivatives, the structure/activity relationship linked to the carbon tail is clarified. We showed that the hydrocarbon tail determines the LPS-binding properties of alterins and consequently their antibacterial activities. Its length and saturation seem to play a major role in this interaction. 相似文献
942.
Mating disruption tactics involve the deployment of pheromones to interfere with mate finding behaviors in insect populations. This management strategy is the dominant one used against expanding gypsy moth populations in the United States, and historically it has been assumed to be most effective against low-density populations. Operationally, mating disruption is used in areas where the season-long trap catch is <30 males/trap, however the maximum population density at which mating disruption is effective remains unknown. We analysed historical gypsy moth mating disruption treatment data from 2000 to 2010, and used this information to guide the mating disruption field studies conducted from 2012 to 2015 against artificially-created populations of various densities, from 0 to 116 males/trap/day. We observed that mating disruption tactics at a dose of 15 g AI/ha were effective against gypsy moth populations with a season-long trap catch of at least 115 males/trap. This research highlights the utility of mating disruption in higher gypsy moth densities than what is currently recommended in management programs. 相似文献
943.
Nathana?l PINGAULT Patrick CARON Alicia KOLMANS Stefanie LEMKE Carol KALAFATIC Sabine ZIKELI Ann WATERS-BAYER Carolin CALLENIUS QIN Yong-jun 《农业科学学报》2020,19(1):291-293
Food Security and Nutrition(FSN) is influenced by diverse and complex factors, and therefore requires a holistic approach to agriculture and food systems plus integration of knowledge from diverse sources in science and society. Using the results of a colloquium held at the University of Hohenheim(Germany) in September 2016 leading up to the recent High Level Panel of Experts(HLPE) Note on Critical and Emerging Issues for Food Security and Nutrition, this article underlines the role of research and innovation as a social and political process and draws attention to neglected types of knowledge. It illustrates the potential of knowledge co-production and co-innovation to transform food systems in order to achieve the Sustainable Development Goals. 相似文献
944.
Jöbstl E Howse JR Fairclough JP Williamson MP 《Journal of agricultural and food chemistry》2006,54(12):4077-4081
Interaction of the tea polyphenol epigallocatechin gallate (EGCG) with beta-casein in milk affects the taste of tea and also affects the stability of the tea and the antioxidant ability of the EGCG. In addition, interaction of polyphenols with the chemically similar salivary proline-rich proteins is largely responsible for the astringency of tea and red wine. With the use of single molecule force microscopy, we demonstrate that the interaction of EGCG with a single casein molecule is multivalent and leads to reduction in the persistence length of casein as calculated using the wormlike chain model and a reduction in its radius of gyration. The extra force required to stretch casein in the presence of EGCG is largely entropic, suggesting that multivalent hydrophobic interactions cause a compaction of the casein micelle. 相似文献
945.
Ten years of fluxes and stand growth in a young beech forest at Hesse, North-eastern France 总被引:1,自引:0,他引:1
André Granier Nathalie Bréda Bernard Longdoz Patrick Gross Jérôme Ngao 《Annals of Forest Science》2008,65(7):704-704
946.
F. Patrick Graz 《European Journal of Forest Research》2008,127(2):165-171
Forestry inventory practices have, in the past, concentrated on obtaining information primarily required for timber management.
To assess the ecological impact of exploitation, particularly under continuous cover forest management, diversity measures
are required that consider the structural diversity in a forest stand. The measure of surround that was initially developed
in Germany may be used to quantify the spatial interspersion of different tree size classes as a measure of spatial diversity.
While the measure of surround has been applied to practical problems in the past, little is known about its actual performance
in relation to stand compositions. This study investigate the behaviour of the index using a number of simulated age class
distributions under various degrees of interspersion to provide a norm against which it may be compared. The measure of surround
applied to diameter distributions is closely related to the diameter structure of a stand. When diameter classes are interspersed
completely randomly within a stand the relative cumulative frequency of the diameter class provides an estimator of the size
specific measure of surround. This provides a baseline from which the index may be interpreted. 相似文献
947.
Patrick V. Vail Donald L. Hostetter Darlene F. Hoffmann 《Integrated Pest Management Reviews》1999,4(3):231-257
A number of the members of the Noctuidae (subfamily Plusiinae) are polyphagous insects that infest a variety of economically important crops world-wide. These hosts include but are not limited to cotton, vegetable and field crops and also such specialty crops as mint. Many of these crops require multiple applications of chemical pesticides to protect them from various loopers and other economic pests. One proposed alternative to the use of chemical pesticides to protect these crops is the development of insect-specific viruses of the family Baculoviridae. Hundreds of these viruses of the genus Nucleopolyhedrovirus have been isolated, many from economically important Lepidoptera. The advent of the discovery that some of these viruses may have a broad host range increased the interest in the development of them as microbial agents throughout the world. The broad host range (over 30 species in some cases) provided the possibility to control not only one species, but a complex of lepidopterous pests infesting specific or multiple crops. From the 1960s to the present, extensive basic and applied research has been conducted on the multi-nucleocapsid (MNPV) forms within which a broad host range appears to be characteristic. Of these, the virus isolated from the alfalfa looper, Autographa californica (Speyer) (AcMNPV) has been the most studied, particularly as related to microbial control. Two of the viruses isolated from loopers have been registered in the USA. Although efficacy has been demonstrated for loopers, there is a paucity of data on the other important species that may simultaneously infest looper hosts. Because of their relatively slow action, the viruses will probably be used in integrated programs with chemical pesticides applied during critical periods of high population pressure. Further research needs to be conducted to establish efficacy for other hosts, improved production methods either in vivo or in vitro, increased field persistence as related to timing and frequency of applications, and finally the utility of genetically engineered MNPVs as microbial pesticides. The potential of these organisms has been demonstrated and new developments are being made to increase the overall efficiency and economics of their use. These improvements can only increase interest in use of the baculoviruses in pest management systems for loopers and other pests. 相似文献
948.
949.
Ronaldo O. Cavalli Gerben Menschaert Patrick Lavens Patrick Sorgeloos 《Aquaculture International》2000,8(1):41-58
The effects of increasing levels of dietaryphospholipids (PL) on the reproductive performance,egg and larval quality, and lipid composition offemales of the freshwater prawn Macrobrachiumrosenbergii were investigated. Three isolipidic dietscontaining similar amounts of highly unsaturated fattyacids but varying levels of PL (0.8, 2.4 and 4.6%)were fed during 180 days to three groups of eightfemales originating from Thai ponds. No significantdifferences were observed for fecundity, egg size andhatchability, starved larvae size, and size, survivaland tolerance to stress of 8 day-old larvae.Similarly, no major differences in the lipidcomposition of the midgut gland, ovaries and muscletissue of females could be detected. Results indicatethe lack of need of dietary supplementation of PL forM. rosenbergii broodstock, as previouslyreported for earlier life stages. It is suggested thatthe basal level of 0.8% dietary PL was sufficient tomeet the dietary demands of the prawn broodstock. ThePL requirements of M. rosenbergii broodstock, ifany, may be satisfied in commercial feeds through theinclusion of ingredients containing some phospholipidsendogenously. 相似文献
950.
Location of Pm3g, a powdery mildew resistance allele in wheat, by using a monosomic analysis and by identifying associated molecular markers 总被引:5,自引:0,他引:5
Pierre Sourdille Patrick Robe Marie-Hélène Tixier Gérard Doussinault Marie-Thérèse Pavoine Michel Bernard 《Euphytica》1999,108(3):193-198
A segregating population of doubled-haploid lines issued from the cross between the wheat (Triticum aestivum L. em. Thell) cultivars Courtot, resistant to several isolates of powdery mildew (Blumeria graminis DC. f. sp. tritici Em. Marchal), and Chinese Spring (susceptible) was used to map Mlar, a gene carried by Courtot and conferring resistance to this pathogen. The assignation of Mlar using monosomic lines of Courtot was confirmed by the mapping analysis. Mlar was located on the short arm of the chromosome 1A, in the vicinity of the locus XGli-A5 coding for storage proteins. This result was in accordance with those demonstrating that Mlar was an allele of the Pm3 locus (Pm3g), a gene also involved in the resistance to powdery mildew.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献