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21.
I Gallien F Caurant M Bordes P Bustamante P Miramand B Fernandez N Quellard P Babin 《Comparative biochemistry and physiology. Toxicology & pharmacology : CBP》2001,130(3):389-395
Top predators from the northern sub-polar and polar areas exhibit high cadmium concentrations in their tissues. In the aim to reveal possible adverse effects, samples of five Atlantic white-sided dolphins Lagenorhyncusacutus have been collected on the occasion of the drive fishery in the Faroe Islands, for ultrastructural investigations and energy dispersive X-ray microanalyses. Cadmium concentrations were less than the limit of detection in both immature individuals and ranged from 22.7 to 31.1 μg g?1 wet weight in the mature individuals. Two individuals with the highest cadmium concentrations exhibited electron dense mineral concretions in the basal membranes of the proximal tubules. They are spherocrystals made up of numerous strata mineral deposit of calcium and phosphorus together with cadmium. Cadmium has been detected with a molar ratio of Ca:Cd of 10:1 in the middle of these concretions. To our knowledge, this is the first report of such granules in a wild vertebrate. The role of these granules in the detoxification of the metal and the possible pathological effects are considered. 相似文献
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Abstract. 1. Clip cages have been used widely by experimental ecologists to contain insects on plants.
2. Under controlled conditions, the effect of applying clip cages alone and clip cages and the chrysomelid beetle Gastrophysa viridula on systemic leaf expansion of Rumex obtusifolius was investigated. Treatments were applied to the fully expanded fourth leaf and expansion of leaf 8 was measured over a period of 22 days.
3. The application of clip cages reduced the rate at which leaf area increased and led to reductions in final leaf areas.
4. Clip cages have systemic effects on plant development and these effects are sustained even after the clip cage is removed. Investigators should take this into account in designing experiments. 相似文献
2. Under controlled conditions, the effect of applying clip cages alone and clip cages and the chrysomelid beetle Gastrophysa viridula on systemic leaf expansion of Rumex obtusifolius was investigated. Treatments were applied to the fully expanded fourth leaf and expansion of leaf 8 was measured over a period of 22 days.
3. The application of clip cages reduced the rate at which leaf area increased and led to reductions in final leaf areas.
4. Clip cages have systemic effects on plant development and these effects are sustained even after the clip cage is removed. Investigators should take this into account in designing experiments. 相似文献
24.
Summary Seed mass and genotypic effects on the growth and reproduction of Oenothera biennis L. over a gradient of intraspecific density were examined in a greenhouse experiment. By using genetically identical seeds from five parental genotypes we were able to examine independently the effects of seed mass and genotype on seedling and adult performance. Seedling size was significantly correlated with seed mass for the first five weeks but had no effect on adult size or reproductive output. In contrast, genotype differences became increasingly apparent with time. In particular, there were striking differences in reproductive output among genotypes. Plants grown from two of the genotypes consistently produced more, but lighter, seeds and a greater proportion flowered at high density than the other three genotypes. In all five genotypes, seed number was much more variable than seed mass across the density gradient. Initial seed mass accounted for a significant proportion of the variation in progeny seed mass, and mean seed mass produced in the greenhouse was positively correlated with mean seed mass of the parent (in the field). This result, together with the observed constancy of seed mass within a genotype across the density gradient, indicates the differences in reproductive output among these genotypes are genetically determined. 相似文献
25.
Radioiodination of highly purified human follicle-stimulating hormone (hFSH) (4000 IU/mg) was performed every other week for 23 weeks using 2 mCi carrier free Na 125I (Amersham Corp., 15 mCi/μg I2) in the presence of lactoperoxidase. Incorporation of 125I into hFSH was determined by the method of [7.]Biochem. J. 89, 114). Hormone binding was studied in vitro under steady-state conditions (16 h, 20°C) using different calf testis membrane preparations having similar receptor characteristics. Each 125I-hFSH preparation was characterized for maximum bindability, specific activity of bindable radioligand as determined by self-displacement analysis, and by determination of Ka and Rt. Incorporation of 125I into FSH was relatively constant over the large number of experiments (62.4 ± 6.4 μCi/μg; n = 23). By comparison, however, specific radioactivity of the receptor bindable fraction of 125I-hFSH was related to the lot of 125I utilized, and was significantly (P ≤ 0.01) lower and more variable (28.7 ± 10.5 μCi/μg). Maximum bindability of 125I-hFSH was not correlated to specific activity (r = 0.06) but was negatively correlated to hFSH 125I incorporation (r = −0.47; P ≤ 0.05). These observations demonstrate the need to assess the quality of each batch of radioligand before undertaking radioligand-receptor assays and suggest that differences in Na125I lots affect specific radioactivity of the radioligand and its receptor binding characteristics. 相似文献
26.
Aminoglycoside suppression at UAG, UAA and UGA codons in Escherichia coli and human tissue culture cells 总被引:6,自引:0,他引:6
Robin Martin Anne E. Mogg Louise A. Heywood Lars Nitschke Julian F. Burke 《Molecular & general genetics : MGG》1989,217(2-3):411-418
Summary We have compared the suppression of nonsense mutations by aminoglycoside antibiotics inEscherichia coli and in human 293 cells. Six nonsense alleles of the chloramphenicol acetyl transferase (cat) gene, in the vector pRSVcat, were suppressed by growth in G418 and paromomycin. Readthrough at UAG, UAA and UGA codons was monitored with enzyme assays
for chloramphenicol acetyl transferase (CAT), in stably transformed bacteria and during transient expression from the same
plasmid in human 293 tissue culture cells. We have found significant differences in the degree of suppression amongst three
UAG codons and two UAA codons in different mRNA contexts. However, the pattern of these effects are not the same in the two
organisms. Our data suggest that context effects of nonsense suppression may operate under different rules inE. coli and human cells. 相似文献
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28.
P. Plaha G. S. Sethi 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1989,77(5):685-688
Summary Thirteen wheat-like advanced-generation triticale x wheat derivatives, having tetraploid wheat cytoplasm from triticale, were reciprocally crossed with three improved bread wheats, and the resulting F1s were evaluated for determining the comparative performance of the bread wheat and triticale cytoplasms for different traits. Significant reciprocal differences in the mean performance were observed for days to heading, days to maturity, spikes/plant, flag-leaf area, peduncle length, plant height, spike length, grains/spike, 1,000-grain weight, grain yield and grain protein content, and most of them were in favour of hexaploid wheat cytoplasm. However, this superiority of the hexaploid cytoplasm was not universal for a particular trait, implying that the differences in the performance of the evaluated reciprocal crosses depended not solely on the cytoplasmic background, but also on the interplay of the specific genotype with the cytoplasm. 相似文献
29.
When cells of the unicellular green alga Chlamydomonas reinhardtii were subjected to microwave irradiation at 2.45 GHz, nitrite uptake kinetics still obeyed the Michaelis-Menten equation, the Km of the process remaining constant, whereas V
max
increased, which indicates an enhanced nonthermal permeability in irradiated cells. 相似文献
30.