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排序方式: 共有121条查询结果,搜索用时 15 毫秒
1.
ANGELA M. GIBSON † N.K. MODI† T.A. ROBERTS† P. HAMBLETON† J. MELLING† 《Journal of applied microbiology》1988,64(4):285-291
A monoclonal antibody-based amplified ELISA method for detecting Clostridium botulinum type B toxin was evaluated for its ability to detect the toxin in the supernatant fluid of pure cultures and after growth from Cl. botulinum spores inoculated into pork slurries. Slurries containing NaCl (1.5–4.5%w/v) and polyphosphate (0.3%w/v) were either unheated or heated 80°C/5 min followed by 70°C/2 h before incubation at 15°, 20° or 27°C. Presence of specific toxin was confirmed by mouse bioassay and results were compared with those of the amplified ELISA method. A total of 48 strains, consisting of 38 Cl. botulinum and 10 Cl. sporogenes (putrefactive anaerobes), and 140 slurry samples were tested. Cultures of eight out of nine strains of type B Cl. botulinum and 73 of 101 slurry samples containing type B toxin were positive by ELISA; the remaining 28 slurry samples contained type B toxin at levels below or close to the detection limit (20 LD50 /ml) of the type B ELISA. No falsepositive reactions occurred with Cl. botulinum types A, C, D, E or F, or with the 10 strains of Cl. sporogenes. Toxin produced by one strain of Cl. botulinum type B (NCTC 3807) was not detected by this single monoclonal antibody-based amplified ELISA. With a mixture of two monoclonal antibodies, however, the toxin from NCTC 3807 could be detected without reducing the sensitivity of the ELISA. 相似文献
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CARVALHO MARIA ANGELA M.; MONTEIRO WALKYRIA R.; DIETRICH SONIA M. C. 《Annals of botany》1989,63(5):505-514
Adventitious roots arise naturally on petioles of Pereskia grandifoliaHaw. held in light. At about the 12th day after the beginningof the experiment, the root primordia arise in a callus tissuedeveloped from the basal portion of the petiole. Associatedwith the development of the callus, noticeable structural changesoccur in the originating organ. Petioles maintained in darkalso form callus; however, they die in a few days. On the otherhand, petioles treated with GA,, maintained in light, developcallus and survive; but they do not give rise to roots. Someaspects are discussed, such as: the kind of origin observedfor the roots, and the possible physiological basis for theirformation, as wdl as for the inhibition of their appearance Pereskia grandifolia, adventitious root formation, gibberelljc acid, petiole structure, rooting 相似文献
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ANGELA R. FELTOON TRINA GUERRA CATHI LEHN MICHAEL R. J. FORSTNER 《Molecular ecology resources》2007,7(3):433-435
Six polymorphic microsatellite loci were isolated and characterized in the threatened Mexican beaded lizard, Heloderma horridum. The number of alleles per locus ranged from three to 12, with observed heterozygosity estimates ranging from 0.00 to 0.77, and expected heterozygosity estimates ranging from 0.00 to 0.73. These microsatellites will provide a valuable tool for the investigation of the genetic variation and structure of both wild and captive H. horridum populations. 相似文献
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JUDITH M. O’HARE MATTHEW T. O’HARE ANGELA M. GURNELL PETER M. SCARLETT TOM LIFFEN CLAIRE McDONALD 《Freshwater Biology》2012,57(1):104-115
1. Plant physical ecosystem engineers can influence vegetation population and community dynamics by modifying, maintaining or creating habitats. They may also have the potential to act upon biotic processes, such as seed dispersal. 2. Examples exist of reduction in seed dispersal distances in vegetated compared to unvegetated terrestrial environments, and concentration of seed deposits associated with plant patches. Such effects in aquatic environments have been little studied, but the engineering effect of plant patches on patterns of flow velocity and sediment deposition in streams suggests that they may play a similar role. 3. In this study, we assess the potential of an emergent aquatic species, Sparganium erectum, to play a role in physically modifying river habitats and trapping seeds by examining patterns of seed deposition and substrate type in 47 river reaches across England and southern Scotland, U.K. 4. Areas of the river channel within or adjacent to S. erectum patches harboured more plant seeds and more species than unvegetated areas and had finer, sandier substrates with higher organic matter, total nitrogen and total phosphorus content. Most seed species were competitive, indicating that they were well suited to colonise the competitive environment of an S. erectum patch, and could potentially further stabilise accumulated sediments and contribute to landform development. 5. We demonstrate that S. erectum patches influence both the physical environment and the retention of seeds, in consistent patterns across the channel bed, for a range of lowland rivers that vary in stream power and geology and which can be expected to vary in levels of supply of fine sediment and seeds. 6. Our findings support the hypothesis that the fundamental influence of a riverine ecosystem‐engineering species on slowing fluid flow links the habitat creation process of sediment sorting and retention to seed trapping. We suggest the process is applicable to a wide range of aquatic and riparian vegetation. We also suggest that the mono‐specific and competitive growth, which is typical of these engineering species, will strongly influence the recruitment of trapped seeds. 相似文献
10.
Shaking a leg and hot to trot: the effects of body size and temperature on running speed in ants 总被引:1,自引:0,他引:1
Abstract. 1. Data were compiled from the literature and our own studies on 24 ant species to characterise the effects of body size and temperature on forager running speed.
2. Running speed increases with temperature in a manner consistent with the effects of temperature on metabolic rate and the kinetic properties of muscles.
3. The exponent of the body mass-running speed allometry ranged from 0.14 to 0.34 with a central tendency of approximately 0.25. This body mass scaling is consistent with both the model of elastic similarity, and a model combining dynamic similarity with available metabolic power.
4. Even after controlling for body size or temperature, a substantial amount of inter-specific variation in running speed remains. Species with certain lifestyles [e.g. nomadic group predators, species which forage at extreme (>60 °C) temperatures] may have been selected for faster running speeds.
5. Although ants have a similar scaling exponent to mammals for the running speed allometry, they run slower than predicted compared with a hypothetical mammal of similar size. This may in part reflect physiological differences between invertebrates and vertebrates. 相似文献
2. Running speed increases with temperature in a manner consistent with the effects of temperature on metabolic rate and the kinetic properties of muscles.
3. The exponent of the body mass-running speed allometry ranged from 0.14 to 0.34 with a central tendency of approximately 0.25. This body mass scaling is consistent with both the model of elastic similarity, and a model combining dynamic similarity with available metabolic power.
4. Even after controlling for body size or temperature, a substantial amount of inter-specific variation in running speed remains. Species with certain lifestyles [e.g. nomadic group predators, species which forage at extreme (>60 °C) temperatures] may have been selected for faster running speeds.
5. Although ants have a similar scaling exponent to mammals for the running speed allometry, they run slower than predicted compared with a hypothetical mammal of similar size. This may in part reflect physiological differences between invertebrates and vertebrates. 相似文献