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1. Spermatozoa in semen samples from 8 individual male domestic fowls were shown to have a differential and characteristic ability to hydrolyse holes in the inner perivitelline layer from laid eggs in an in vitro assay. 2. The number of holes produced by samples of spermatozoa per unit area of inner perivitelline layer in vitro was linearly correlated with sperm ATP content ( r = 0.85) and motility (r=0.76). 3. The number of holes formed in the inner perivitelline layer in vitro was also linearly correlated with the numbers of holes formed in the inner perivitelline layer of eggs fertilised in vivo , in inseminated hens (r=0.90); and was correlated logarithmically with the proportion of fertile eggs laid by these hens.  相似文献   
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Abstract. The specificity and kinetics of the immune response of rainbow trout ( Salmo gairdneri ) to single injections of an O-antigen extracted from the bacterial pathogen Yersinia ruckeri , which causes enteric redmouth in fish, were investigated by the passive haemolytic plaque assay and serum antibody quantitation. Doses ranging from 5 ng to 500 mg in 10-fold increments were injected intraperitoneally into groups of trout held at 17 × 1°5°C. The occurrence of plaque forming cells (PFC) and humoral antibody was followed for 35 days after injection. Trout gave an immune response to doses of 500 ng and above. Seven days after injection no humoral antibody was detected, but PFC were found in the spleen. The maximum PFC numbers occurred 11 days after injection. On day 21, few PFC were found, whereas serum antibody titres were highest. The antibody from immunized trout showed little or no cross-reactions with sheep red blood cells passively labelled With antigens from other fish pathogens.  相似文献   
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Plants of Ulex europaeus were grown from cuttings and studies made of the absorption of 14C-picloram applied with unlabelled 2,4,5-T. In vivo experiments in a growth chamber showed that absorption ceased after 10 h, but was resumed on wetting. In in vitro experiments the Q10 and the activation energy for uptake decreased with increasing temperature. Absorption was increased by addition of non-ionic surfactants, by lowering the pH and by removal of cuticular wax. Gorse shoots were shown to have a high wax content but scanning electron microscopy revealed no obvious wax structures and the contact angle of spray droplets was less than 900, indicating that the surfaces were not difficult to wet.  相似文献   
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Abstract. Sections of the bottom of three earthen fish ponds in central Scotland were enclosed to prevent access by juvenile brown trout, Salmo trutta L., stocked at different densities from July to October. Monthly benthic samples were taken inside and outside the enclosures with a suction sampler. The benthos was dominated by Oligochaeta, whose density and biomass were significantly lower outside the enclosures; production was also lower outside but the P:B ratio was much higher. Total Chironomidae were more abundant outside, but not the larger predatory species which appeared to control the inside population. Species diversity of Oligochaeta and Chironomidae was greater outside while mean size was reduced, presumably as a result of size-selective predation by trout. Numbers of Mollusca and Asellidae were lower in the presence of fish, but Hirudinea and Sialidae were unaffected. Increasing fish density boosted chironomid numbers and biomass, indicating a predominant response to organic enrichment, but reduced the numbers of most other benthic groups presumably as a result of predation.  相似文献   
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This series of papers examines some significant differences in the constitution of organic matter found amongst major soil groups and their genetic and morphological horizons, as determined by the dynamic pyrolysis-mass spectrometry of whole soil samples. Multivariate methods of data analysis identify groups of co-variant mass ions which successfully partition samples in terms of the above soil categories, and correlate with other major properties such as humification and hydromorphism. This first study covers the A horizons from a group of 22 Scottish soils chosen from the major temperate soil groups including brown forest soils, podzols, and noncalcareous, peaty and humic gleys (phaeozems, cambisols, podzols and gleysols). The principal components analysis of 52 mass ion intensities was found to partition the soils successfully in terms of two main factors which represented 62% of the total statistical variance. The first factor was found to correspond closely to the extent of hydromorphism, being high for highly gleyed A horizons, and depended chiefly on the presence of aromatic hydrocarbon ions. The second factor corresponded to the extent of mull humus formation, being high for brown forest soils (phaeozems, cambisols) and low for podzols, and depended chiefly on the abundance of polypeptide products relative to polysaccharide products. This second factor was evidently a more comprehensive expression of a humification factor found in previous studies. The relationships of these factors with C and N content and with base status properties were examined.  相似文献   
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