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A practical and convenient method of rearing Eucyclops serrulatus in a microculture environment is described. A complete life cycle of E. serrulatus was maintained in a narrow space on a microscope slide glass on which a cover glass of 22 x 40 mm in size was mounted at a height of 0.8 mm. The culture medium was constituted by bottled mineral water boiled with grains of Glycine max (soybean). Chilomonas paramecium, a free-living protozoan organism, was provided as live food. Growth of nauplii hatched from eggs to the first stage of copepodite took an average of 7.7 days, and the growth of copepodite 1 to the egg-bearing adult female took an average of 20.1 days in the microculture cell with an average life time of 44.7 days. Continuous passage of copepods was successfully maintained as long as sufficient medium and food were provided. The microculture method enables an in situ microscopic observation on the growth and developmental process of helminth larvae experimentally infected to copepods as well as of copepod itself. Furthermore, it does not require anesthetization and, therefore, minimize the amount of stress exposed to copepods during the handling process.  相似文献   
2.
A toxin with four disulfide bridges from Tityus serrulatus venom was able to compete with 125I‐kaliotoxin on rat brain synaptosomal preparations, with an IC50 of 46 nM . The obtained amino acid sequence and molecular mass are identical to the previously described butantoxin. Enzymatic cleavages in the native peptide followed by mass spectrometry peptide mapping analysis were used to determine the disulfide bridge pattern of α‐KTx12?1. Also, after the cleavage of the first six N‐terminal residues, including the unusual disulfide bridge which forms an N‐terminus ring, the potency of the cleaved peptide was found to decrease about 100 fold compared with the native protein. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.  相似文献   
3.
Small and relatively isolated populations that occupy fragmented habitat are at risk of local extinction. However, fitness consequences of fragmentation related to mating distance, such as inbreeding depression following increased self- and near-neighbor mating, may not follow standard expectations in species with specialized genetic systems. We investigated the effect of mating distance on progeny fitness in Calylophus serrulatus, a primarily autogamous, permanent translocation heterozygote that is restricted to prairie fragments in the North American tallgrass prairie region. We pollinated flowers by hand in the field with pollen sampled at various distances from the maternal parent within and between three populations in southeastern Minnesota. We raised the progeny in a greenhouse and measured fitness-related characters. Because their genetic system prevents loss of heterozygosity throughout much of the genome, regardless of inbreeding, permanent translocation heterozygotes are not expected to exhibit inbreeding depression. Consistent with this expectation, in no case did progeny of self matings suffer significantly reduced mean fitness compared to progeny from crosses between plants. Crosses between plants in the two closely situated (2 km) populations yielded progeny with fitness intermediate to their parents, but crosses between each of those populations and the more distant (20 km) population yielded progeny with reduced fitness, suggesting outbreeding depression at this largest spatial scale. Similarly, fitness of self-pollinated progeny and progeny from "near" crosses (<2 m) within populations tended to be higher than "mid" (10-25 m) and "far" (>35 m) cross-progeny fitness. Under the current conditions of fragmentation, it seems likely that the distant matings that produce outbreeding depression are rare. It appears that mean fitness in this species is maintained in the context of severe fragmentation of its populations, largely because of its genetic system.  相似文献   
4.
1. This work investigated the consumption of a microalgal (Anabaena spiroides) exopolysaccharide by the cladoceran Simocephalus serrulatus (Cladocera, Daphnidae) and its effect on copper toxicity. 2. Total organic carbon concentration was used to quantify the microalgal exopolysaccharide. Both copper‐complexed exopolysaccharides and copper‐free exopolysaccharides were taken up by S. serrulatus. 3. A reduction of free copper ions was obtained in the presence of A. spiroides exopolysaccharide. Copper toxicity (EC50) and zooplankton concentrations were inversely correlated to exopolysaccharide concentration in experimental media. 4. An increase of free copper ions in experimental media was obtained after exopolysaccharide consumption, suggesting that S. serrulatus excreted copper to the surrounding environment.  相似文献   
5.
Species of Diptera (larval Culicidae, Chironomidae and Simuliidae) and Crustacea (cladoceran adults) that are representative of the fauna of aquatic alpine ecosystems are routinely treated with Bacillus thuringiensis var. israelensis (Bti) for mosquito control. The toxicity of Bti on these organisms was investigated. Bioassays indicated that Bti used at the concentration for operational field application is deleterious to all dipteran species, but not to Cladocera. Histopathological observations reveal that, in all cases, the midgut epithelium is affected by Bti treatment. However, the vulnerability of epithelial cells to the microbial insecticide is different from one cell-type to another, clear cells being more vulnerable than dark cells. Because of the concentration of clear cells within the anterior midgut of dipteran larvae, this region appears to be the first to show symptoms of intoxication through enhancing a natural process of cell turnover. The relative importance of such a vulnerable region in the midgut of dipteran larvae may account for the general efficacy of Bti to these species. Its harmlessness to Cladocera may be correlated to the relative scarcity of clear cells and their patchy distribution along the whole midgut together with important cellular renewal capacity of the epithelium.  相似文献   
6.
Cell suspension cultures of Penstemon serrulatus Menz. reached their maximum biomass after 12th days' growth and produced cis and trans verbascoside at 6.1 g l–1. Leucoseptoside A (0.65 g l–1) and martynoside (0.42 g l–1) were also produced.  相似文献   
7.
为研究隆线溞(Daphnia carinata)、锯缘真剑水蚤(Eucyclops serrulatus)及中华薄壳介(Dolerocypris sinensis)3种甲壳纲动物种群与萼花臂尾轮虫(Brachionus calyciflorus)种群的相互关系,作者分别将其以不同接种密度与萼花臂尾轮虫(接种密度为350 ind/L)进行混合培养。轮虫种群密度增长率自混合培养后的第3或4天开始下降,且随着甲壳纲动物接种密度的增加轮虫种群受到的抑制作用增大。当轮虫接种密度为350 ind/L时,3种甲壳纲动物的种群变化有所不同:(1)当隆线溞起始密度低于150 ind/L时,其种群生长受到轮虫的明显抑制;而当隆线溞起始密度达到350 ind/L时,其在混合培养与单独培养下的种群变化基本一致,这表明轮虫对隆线溞种群生长无抑制作用。(2)与隆线溞不同,锯缘真剑水蚤和中华薄壳介在混合培养下的种群数量持续增长。但与锯缘真剑水蚤相比,中华薄壳介在混合培养下的种群增长速度较慢。  相似文献   
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