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961.
Incubation in gibberellin A3 (GA3) or a 1 h immersion pretreatment with 800 mm sodium hypochlorite (NaOCl) both promoted 20% germination of freshly harvested dormant wild oat (Avena fatua L.) seeds that had been imbibed on water for 10 days. GA3 immediately following 1 h NaOCl immersion pretreatment induced maximum germination. Moist storage (MS) after NaOCl immersion pretreatment resulted in less germination on transference of the seeds to GA3, indicating that GA3 responsiveness was lost during MS. These seeds required a repeal NaOCl immersion plus a GA3 treatment to induce maximum germination. However, GA3 still gave maximum germination if the seeds were stored dry after initial NaOCl immersion. Seeds with water-induced dormancy responded similarly to freshly harvested dormant seeds when treated with NaOCl, MS, or GA3. Seeds afterripened a longer time had a reduced requirement for exogenous GA3 in the breaking of dormancy indicating that the depth of the GA3-dependent dormancy decreased with duration of after-ripening. Dormant dehulled seeds with a brief NaOCl pretreatment germinated about 30% on water but gave maximum germination when incubated on GA3, an effect that persisted even after 21 days of MS. This effect, coupled with the previous findings, suggested that the NaOCl treatment weakened membrane barriers of the seed coat through a scarification-like effect, similar to the effects of piercing and acid immersion, and thereby produced increased sensitivity to the presence of GA3. The loss of responsiveness to GA3 in NaOCl-treated seeds during MS may involve the restoration of integrity of the seed coverings, a process occurring only in the imbibed state, and, presumably, most rapidly in freshly harvested, intact seeds. 相似文献
962.
Pulmonary recruitment of neutrophils and bacterial clearance in mice inoculated with aerosols of Pasteurella haemolytica or Staphylococcus aureus. 下载免费PDF全文
J Martínez-Burnes A López M Merino-Moncada P Ochoa-Galván I Mondragón 《Canadian journal of veterinary research》1985,49(3):327-332
Pulmonary alveolar macrophages are considered to be the main phagocytic cell of the pulmonary defense mechanism. However recent studies indicate that neutrophils may also participate in the defense against inhaled bacteria. The aim of this investigation was to study in mice the correlation between numbers of phagocytic cells in the bronchoalveolar space and the pulmonary clearance of bacteria. White mice were exposed to aerosols of Pasteurella haemolytica (n = 129) or Staphylococcus aureus (n = 129) in three different experimental replicates. Another group of mice (n = 22) was sham exposed to an aerosol of sterile phosphate buffered solution in a single replicate. Animals were sacrificed at various times postaerosolization. The numbers of neutrophils and alveolar macrophages in lung lavages and the pulmonary bacterial clearance rates were determined and statistically analysed. No significant differences (p greater than 0.05) were observed in the rates of pulmonary clearance between the two genera of bacteria, but P. haemolytica had a significant (p less than 0.05) replicate effect. The number of alveolar macrophages was not significantly affected by either bacteria or phosphate buffered solution. Exposure to P. haemolytica resulted in dramatic, significant (p less than 0.01) but transient increases in neutrophils in the bronchoalveolar space as well as a significant (p less than 0.01) increase in the weights of lung. The correlation between neutrophils and clearance was positive for P. haemolytica but negative for S. aureus. These results indicate that both species of bacteria are rapidly eliminated from the lung despite a rather different cellular response. 相似文献
963.
Streptococcus Suis: Past and Present 总被引:109,自引:0,他引:109
Staats J.J. Feder I. Okwumabua O. Chengappa M.M. 《Veterinary research communications》1997,21(6):381-407
Staats, J.J., Feder, I., Okwumabua, O. and Chengappa, M.M., 1997. Streptococcus suis: past and present. Veterinary Research Communications, 21 (6), 381-407Steptococcus suis is a Gram-positive, facultatively anaerobic coccus that has been implicated as the cause of a wide range of clinical disease syndromes in swine and other domestic animals. In swine, the disease has spread worldwide but is more prevalent in countries with intensive swine management practices. The disease syndromes caused by S. suis in swine include arthritis, meningitis, pneumonia, septicaemia, endocarditis, polyserositis, abortions and abscesses. S. suis has also been implicated in disease in humans, especially among abattoir workers and swine and pork handlers. In humans, S. suis type 2 can cause meningitis, which may result in permanent hearing loss, septicaemia, endocarditis and death. The pathogenic mechanism of S. suis is not well defined. Several virulence factors have been identified, but their roles in pathogenesis and disease have not been well elucidated. Much work is in progress on characterization of virulence factors and mechanisms, with emphasis on the control of the disease. Because of the non-availability of suitable immunoprophylaxis, control of S. suis infection has depended mainly on the use of antimicrobials. 相似文献
964.
965.
Four two-year-old Thoroughbreds suffered an acute gastrointestinal illness shortly after dosing with mineral oil which was thought to have been contaminated with an organophosphate compound. Three weeks later all four were noted to be dyspnoeic and endoscopic examination showed that they had developed bilateral laryngeal paralysis. Two of the horses died during severe bouts of dyspnoea six and eight months later and the third was killed shortly thereafter. Examination of the left and right recurrent laryngeal nerves from these horses showed a severe loss of myelinated fibres distally, especially in the left nerve. A similar but less severe lesion was seen in other long peripheral nerves, including the phrenic and digital nerves of the third horse. The spinal cord in two horses showed evidence of mild axonal degeneration which was not related to a particular tract or location. The fourth horse had bilateral laryngeal paralysis two years later. The acute clinical signs and delayed neurological sequelae seen in these horses were strongly suggestive of accidental organophosphate toxicity. 相似文献
966.
C L?mmler I W Wibawan 《Zentralblatt für Veterin?rmedizin. Reihe B. Journal of veterinary medicine. Series B》1990,37(3):173-176
Streptococcal group-specific antigens and B-streptococcal type antigens were solubilized with a murolytic enzyme from Staphylococcus hyicus. This facilitated the effective serogrouping and serotyping of streptococci isolated from humans and various animals. 相似文献
967.
968.
969.
Winston I 《Science (New York, N.Y.)》1901,13(317):129-133
970.