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Hans Grisebach 《Die Naturwissenschaften》1977,64(12):619-625
The complete set of enzymes that catalyze the reactions from l-phenylalanine to substituted cinnamyl alcohols is now known. The latter compounds are the primary building stones of lignin. The individual reactions and the possible modes of regulation of this pathway are discussed. The polymerization of cinnamyl alcohols to lignin is mediated by peroxidase. The significance of cell-wall-bound peroxidases in this process and the origin of hydrogen peroxide are reviewed. Finally, the possible role of lignification in relation to disease resistance is discussed. 相似文献
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莫新萍 《石油化工环境保护》2002,25(4):41-44
利用测微技术对扬子石化公司水厂厌氧装置进行菌种分布,颗粒污泥粒径的测定,从微观的角度来反映装置的运行情况,为实际运行操作提供参考。 相似文献
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Results from no-choice field and greenhouse studies established an inverse relationship between plant trichome density in cotton and the level of successful attacks on Heliothis zea (Boddie) eggs by the parasite, Trichogramma pretiosum (Riley) and the predator, Chrysopa rufilabris (Burmeister). Thus, plant damage from H. zea can be reduced on glabrous cotton phenotypes due to antixenosis and increased entomophage effectiveness compared to hirsute and pilose phenotypes. Studies by other scientists which demonstrate interactions of natural enemies with host-plant resistance in cotton are also discussed. Symbiotic relationships between the host-plant and its associated predator/parasitoid complex may significantly influence the expression of host-plant resistance in cotton. Scientists involved in programs for development of host-plant resistant cultivars are encouraged to utilize sources of resistance which increase effectiveness of key natural enemies of the major pest species. 相似文献
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复合垂直流人工湿地基质生化活性研究 总被引:2,自引:1,他引:2
文章测定了复合垂直流人工湿地基质生物膜生物量的空间分布、纤维素分解作用强度、氨化作用强度、酚分解作用强度、耗氧速率、厌氧活性等指标,结果表明:下行流池基质的纤维素分解作用、氨化作用、酚分解作用、耗氧速率等均高于上行流池,表层高于中下层,各指标变化趋势与生物膜生物量的空间分布存在明显的一致性;下行流池表层基质是污染物降解的主要空间;但上行流池基质的厌氧活性高于下行池;同时发现钴离子对基质厌氧微生物活性存在一定的影响,随着浓度的升高表现为先激活后降低。这些研究为阐明人工湿地净化机理提供了理论依据。 相似文献
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Thomas Chouvenc Caroline A. Efstathion Monica L. Elliott Nan-Yao Su 《Die Naturwissenschaften》2012,99(11):949-958
Subterranean termites live in large groups in underground nests where the pathogenic pressure of the soil environment has led to the evolution of a complex interaction among individual and social immune mechanisms in the colonies. However, groups of termites under stress can show increased susceptibility to opportunistic parasites. In this study, an isolate of Aspergillus nomius Kurtzman, Horn & Hessltine was obtained from a collapsed termite laboratory colony. We determined that it was primarily a saprophyte and, secondarily, a facultative parasite if the termite immunity is undergoing a form of stress. This was determined by stressing individuals of the Formosan subterranean termite Coptotermes formosanus Shiraki via a co-exposure to the virulent fungal parasite Metarhizium anisopliae (Metch.) Sorokin. We also examined the dynamics of a mixed infection of A. nomius and M. anisopliae in a single termite host. The virulent parasite M. anisopliae debilitated the termite immune system, but the facultative, fast growing parasite A. nomius dominated the mixed infection process. The resource utilization strategy of A. nomius during the infection resulted in successful conidia production, while the chance for M. anisopliae to complete its life cycle was reduced. Our results also suggest that the occurrence of opportunistic parasites such as A. nomius in collapsing termite laboratory colonies is the consequence of a previous stress, not the cause of the stress. 相似文献
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Mark K. Greco Dorothee Hoffmann Anne Dollin Michael Duncan Robert Spooner-Hart Peter Neumann 《Die Naturwissenschaften》2010,97(3):319-323
Workers from social insect colonies use different defence strategies to combat invaders. Nevertheless, some parasitic species
are able to bypass colony defences. In particular, some beetle nest invaders cannot be killed or removed by workers of social
bees, thus creating the need for alternative social defence strategies to ensure colony survival. Here we show, using diagnostic
radioentomology, that stingless bee workers (Trigona carbonaria) immediately mummify invading adult small hive beetles (Aethina tumida) alive by coating them with a mixture of resin, wax and mud, thereby preventing severe damage to the colony. In sharp contrast
to the responses of honeybee and bumblebee colonies, the rapid live mummification strategy of T. carbonaria effectively prevents beetle advancements and removes their ability to reproduce. The convergent evolution of mummification
in stingless bees and encapsulation in honeybees is another striking example of co-evolution between insect societies and
their parasites. 相似文献
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N.E. Rees 《Agriculture, ecosystems & environment》1985,12(2):157-163
Three species of Sacrophagidae (Diptera) and four of Scelionidae (Hymenoptera) that are parasites of grasshoppers or grasshopper eggs in Pakistan were imported into the United States and exposed to 16 and 24 species of North American grasshoppers representing the three major sub-families. The hosts that were provided were unacceptable, and the exotic parasites were not promising for control of American grasshoppers. 相似文献
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Neumann P Pirk CW Hepburn HR Solbrig AJ Ratnieks FL Elzen PJ Baxter JR 《Die Naturwissenschaften》2001,88(5):214-216
Worker honeybees (Apis mellifera capensis) encapsulate the small hive beetle (Aethina tumida), a nest parasite, in propolis (tree resin collected by the bees). The encapsulation process lasts 1-4 days and the bees have a sophisticated guarding strategy for limiting the escape of beetles during encapsulation. Some encapsulated beetles died (4.9%) and a few escaped (1.6%). Encapsulation has probably evolved because the small hive beetle cannot easily be killed by the bees due to its hard exoskeleton and defensive behaviour. 相似文献
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Schmid-Hempel P 《Die Naturwissenschaften》2001,88(4):147-158
Over the last decade, there has been a major shift in the study of adaptive patterns and processes towards including the role of host-parasite interactions, informed by concepts from evolutionary ecology. As a consequence, a number of major questions have emerged. For example, how genetics affects host-parasite interactions, whether parasitism selects for offspring diversification, whether parasite virulence is an adaptive trait, and what constrains the use of the host's immune defences. Using bumblebees, Bombus spp, and their parasites as a model system, answers to some of these questions have been found, while at the same time the complexity of the interaction has led expectations away from simple theoretical models. In addition, the results have also led to the unexpected discovery of novel phenomena concerning, for instance, female mating strategies. 相似文献
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Carry-over effects refer to processes that occur in one season and influence fitness in the following. In birds, two costly activities, namely reproduction and moult, are restricted to a small time window, and sometimes overlap. Thus, colour in newly moulted feathers is likely to be affected by the costs of reproduction. Using models of bird vision we investigated male colour change in a free-living population of blue tits (Cyanistes caeruleus) in three sampling occasions: spring 1, winter and spring 2. We related crown, tail, breast and cheek feather colouration after the moult (winter) to the intensity of infections by blood parasites during reproduction (spring 1). In the following spring (spring 2), we explored mating patterns with respect to changes in feather colour (springs 1 vs. 2). Males that were less intensely infected by the malaria parasite Plasmodium while breeding showed purer white cheek feathers in winter, which may indicate higher feather quality. Increased brightness in the white cheek was associated with better body condition during reproduction. In the following season, males with brighter cheeks paired with females that had noticeably brighter cheek patches compared to the male’s previous mate. These results suggest that the conditions experienced during reproduction are likely to affect moult and thus feather colouration, at least in the white patch. High quality individuals may allocate resources efficiently during reproduction increasing future reproductive success through variation in mating patterns. Carry-over effects from reproduction might extend not only to the non-breeding phase, but also to the following breeding season. 相似文献
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根据连云港市污染物排放量的比较和污染减排任务的要求,选取COD和NH3-N 2种具有代表性的污染物,详细研究连云港市工业行业的COD和NH3-N产、排量,根据数据测算出所占排放量比重,对比重较大的饮料制造业、食品加工业和化学品原料及化学品制造业的污染治理设施进行了详细调查,发现治理设施大部分为生物接触氧化法等废水生物处理法进行有机物治理.总结了连云港市在工业废水处理设施中存在的问题,提出对策与建议. 相似文献
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以某区域水环境-经济系统为研究实例,寻求值-排污-水质综合协调解方法,寻求净收益最大时的总体规划方案。建立目标参数规划模型,寻求不同生产规模条件下的产值-排污-水质协调解,又探讨了水环境标准约束下的某化工区废水治理费用的计算方法,提出了以供决策者选择的方案。 相似文献
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钱苏华 《安全.健康和环境》2010,10(1):33-35
介绍了当前国际化学危险品的各种分类体系,对比了GHS与TDG、EU_CLP、DOT、WHMIS等对化学危险品的具体分类。有助于GHS的理解与掌握,全面推进GHS在我国的实施。 相似文献
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