Out of a total of 224 bovine eye secretions, 126 Moraxella bovis and 64 Neisseria ovis strains were isolated. The pathogenesis and histological lesions caused by Neisseria ovis have been studied on the eyes of three calves naturally affected with IBK, using electron microscopy.
Neisseria ovis caused in 1–12 weeks old calves acute, transient and mostly benign serous conjunctivitis with only slight affection of the cornea. More rarely erosions and even ulceration of the cornea have been observed.
Moraxella bovis and Neisseria ovis strains proved nearly unanimously sensitive in vitro to chloramphenicol, neomycin, oxytetracyclin, nitrofurantoin, erythromycin and cefoperazone. Other antibiotics and chemotherapeutics inhibited the growth of these agents only partly or were ineffective.
Experimental therapy has been carried out using a single i.m. injection of Terramycin/LA inj. (Pfizer) in a dose of 20 mg/kg body mass, repeated if necessary after 72–96 h. This formulation proved more effective and practical than treatments used earlier. 相似文献
AbstractGrowth and structural changes in the seminal root tip of rice seedlings (Oryza sativa L. cv. Nipponbare) in response to NaCl salinity were studied. Seedlings were grown in agar medium with 0, 0.1, 0.3, 1.0, 2.0 and 3.0% NaCl(agar culture), and in water with 0, 0.01, 0.03, 0.06 and 0.1% NaCl (water culture). Seedling growth was significantly suppressed by higher concentrations of NaCl. The effect of NaCl appeared faster in water culture than in agar culture. In both agar and water cultures, root growth was markedly suppressed over shoot growth. Under saline conditions, epidermis, cortex and root cap cells appear to be damaged to a greater extent than the meristem and stelar cells. The most notable ultrastructural change in response to salinity was the development and increment of vacuoles, which seem to provide a space for accumulation of excess ions. Many electron dense deposits were observed in the larger vacuoles of the epidermal and cortical cells. Under saline conditions, cell wall thickening of the epidermis, an increase in endoplasmic reticulum, myelin figures, less compact Golgi bodies and inhibited production of Golgi vesicles were also observed. 相似文献
Strong adhesion between the hull and the caryopsis is essential for barley to be of good malting quality. Poor hull adhesion, a condition known as grain skinning, is undesirable for malting and downstream processes. At present, the processes mediating hull adhesion during grain development are poorly understood. The barley cultivar Chariot was grown in greenhouse conditions and grain development was recorded at defined growth stages to examine the timing of hull adhesion. Initiation of adhesion was first observed when caryopsis fresh weight and volume were approaching their maximum at 19 days after anthesis, during early dough. Hull adhesion was complete by 27 days after anthesis, or soft dough. Sections of developing grains were observed using light and transmission electron microscopy to examine a lipid-rich cementing layer believed to be responsible for adhesion between the hull and the pericarp. Evidence for a lipid-rich cementing material was supported by the observation that neither pectinase nor cellulase effected hull loosening. Grain growth, the presence of globular material originating from the pericarp and an electron dense material in the cementing layer are discussed in relation to hull adhesion. Grain skinning could be caused by poor adherence of cuticular material or inadequate fusion between cuticles. 相似文献