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A. S. J. P. A. M. VAN MIEKT C. T. M. VAN DUIN Th. WENSING† 《Journal of veterinary pharmacology and therapeutics》1992,15(4):332-342
Tumour necrosis factor (TNF), a polypeptide produced by mononuclear phagocytes, has been implicated as an important mediator of inflammatory processes and of clinical manifestations in acute infectious diseases. To study further the potential role of TNF in infectious diseases, recombinant Escherichia coli (E. coli) derived human (r.HuTNF-alpha) and bovine TNF (r.BoTNF-alpha) were intravenously (i.v.) administered in dwarf goats. Rectal temperature, heart rate, rumen motility, plasma zinc and iron concentrations, and certain other blood biochemical and haematological values were studied and compared with the changes seen after E. coli endotoxin (LPS) was administered (dose: 0.1 microgram/kg i.v.). Following a single injection of 4 micrograms/kg of r.BoTNF-alpha, shivering and biphasic febrile response were observed, accompanied by tachycardia, inhibition of rumen contractions, drop in plasma zinc and iron concentrations, lymphopenia, and neutropenia followed by neutrophilia. The i.v. administration of a single injection of 4 micrograms/kg r.HuTNF-alpha induced shivering and biphasic febrile responses, accompanied by anorexia and a similar drop in plasma trace metal concentrations when compared with r.BoTNF-alpha-treated goats. The TNF-alpha-induced symptoms were essentially the same as those that occurred after LPS administration. However, the time of onset of these changes after the injection of TNF-alpha was significantly shorter than after LPS. Moreover, the r.BoTNF-alpha induced a longer lasting neutrophilic leucopenia, less neutrophilia, and a more persistent lymphopenia than after LPS injection. Neither r.BoTNF-alpha nor LPS caused severe haemo-concentration. Furthermore, no cross-tolerance between r.BoTNF-alpha and LPS could be demonstrated. We conclude that both r.BoTNF-alpha and r.HuTNF-alpha induce many of the physiologic, haematologic and metabolic changes that characterize the acute phase response to LPS. The overlapping biological activities of r.BoTNF-alpha, r.HuTNF-alpha and LPS in dwarf goats may indicate that both recombinant tumour necrosis factors have some homology with caprine TNF-alpha. 相似文献
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A new dynamic model of the infection of apple leaves by Venturia inaequalis is described. The model begins with the release of spores by rain and incorporates the effect of light on the discharge of ascospores from pseudothecia. The model then simulates infection through the sub-processes of germination, appressorium formation and penetration, separately for ascospores and conidia landed concurrently on wet leaves. The rate of the infection process is determined using different equations for ascospores and conidia. Spore mortality when leaves dry is determined by the stage of infection and RH in the dry period. The infection process is driven by surface wetness, temperature and RH. The progress of each infection period is measured as infection efficiency (IE), namely the percentage of landed spores which have penetrated and thereby infected leaves. The final IE quantifies the favourability of weather in each infection period. In orchard tests in each of three years, the new model detected crucial infection periods in spring and early summer which accounted for outbreaks of leaf scab. These periods were not detected by a static model based on Mills'criteria. The models performed similarly in detecting infection periods later in summer. 相似文献
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The influence of pre-treatment and post-treatment illumination upon the herbicidal effect produced in Phaseolus vulgaris L. cv. Berna by simeton, diuron, diquat and ioxynil was examined. The increased effect noted at lower pre-treatment and higher post-treatment levels of illumination was correlated with increased inhibition of net photosynthesis. This increased effect was ascribed to enhanced photo-oxidation. 相似文献
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Summary. After the 4- or 5-leaf stage in young barley plants, there is a decrease in the translocation of 2,4-D from the leaves to the root system. It is shown that there is no relation between this phenomenon and ear initiation, which occurs at this stage of development. Movement of 2,4-D out of leaves of the tiller in the axils of the 1st and 2nd leaves was also shown to be very small. There is some evidence for a'block'in the movement of 2,4-D in established grass plants.
La migration du 2,4-D marqué dans l'orge 相似文献
La migration du 2,4-D marqué dans l'orge 相似文献
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Lyn A. HINDS Steve HENRY Nikki VAN DE WEYER Freya ROBINSON Wendy A. RUSCOE Peter R. BROWN 《Integrative zoology》2023,18(1):63-75
Irregular plagues of house mice, Mus musculus, incur major economic impacts on agricultural production in Australia. The efficacy of zinc phosphide (ZnP), the only registered broadacre control agent for mice, is reported as increasingly variable. Have mice become less sensitive over time or are they taking a sub-lethal dose and developing aversion? In this laboratory study, the sensitivity of mice (wild caught; outbred laboratory strain) was assessed using oral gavage of a range of ZnP concentrations. The estimated LD50 values (72–79 mg ZnP/kg body weight) were similar for each mouse group but are significantly higher than previously reported. The willingness of mice to consume ZnP-coated grains was determined. ZnP-coated grains (50 g ZnP/kg grain) presented in the absence of alternative food were consumed and 94% of wild mice died. Mice provided with alternative food and ZnP-coated wheat grains (either 25 or 50 g ZnP/kg grain) consumed toxic and non-toxic grains, and mortality was lower (33–55%). If a sublethal amount of ZnP-coated grain was consumed, aversion occurred, mostly when alternative food was present. The sensitivity of wild house mice to ZnP in Australia is significantly lower than previously assumed. Under laboratory conditions, ZnP-coated grains coated with a new higher dose (50 g ZnP/kg grain) were readily consumed. Consumption of toxic grain occurred when alternative food was available but was decreased. Our unambiguous findings for house mice indicate a re-assessment of the ZnP loading for baits used for control of many rodents around the world may be warranted. 相似文献
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The stages in the formation of Peridermium pini lesions aredescribed. The hyphae of the parasite were septate, uninucleate,and intercellular, with unbranched haustoria penetrating allphloem cells and xylem parenchyma cells. Lesion extension occurredby apical growth of the hyphae along the outer edge of the functionalphloem. The hyphae stretched unbroken across the active cambium.Active centripetal and longitudinal growth of the mycelium occurredin the resin ducts of the xylem, the hyphae commonly reachingthe pith. Spermogonia were produced in late summer and fall,aecia appeared in spring. In lesion xylem, tracheids were shorter,rays taller, more numerous and wider, but ray cell height remainedunchanged. Fusiform rays increased in number and size and verticalresin ducts increased in number. Changes in xylem tissues didnot become evident until two to four years after invasion ofthe cambium by the mycelium. Invasion of the secondary phloemresulted in an increase in number and size of the longitudinalphloem parenchmya cells, while changes in phloem rays were similarto those in xylem rays. 相似文献
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