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501.
Germination, Growth, and Sporulation of Bacillus thuringiensis subsp. israelensis in Excreted Food Vacuoles of the Protozoan Tetrahymena pyriformis
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Robert Manasherob Eitan Ben-Dov Arieh Zaritsky Zeev Barak 《Applied microbiology》1998,64(5):1750-1758
Spores of Bacillus thuringiensis subsp. israelensis and their toxic crystals are bioencapsulated in the protozoan Tetrahymena pyriformis, in which the toxin remains stable. Each T. pyriformis cell concentrates the spores and crystals in its food vacuoles, thus delivering them to mosquito larvae, which rapidly die. Vacuoles containing undigested material are later excreted from the cells. The fate of spores and toxin inside the food vacuoles was determined at various times after excretion by phase-contrast and electron microscopy as well as by viable-cell counting. Excreted food vacuoles gradually aggregated, and vegetative growth of B. thuringiensis subsp. israelensis was observed after 7 h as filaments that stemmed from the aggregates. The outgrown cells sporulated between 27 and 42 h. The spore multiplication values in this system are low compared to those obtained in carcasses of B. thuringiensis subsp. israelensis-killed larvae and pupae, but this bioencapsulation represents a new possible mode of B. thuringiensis subsp. israelensis recycling in nontarget organisms. 相似文献
502.
Δ9-Tetrahydrocannabinol, administered intravenously in doses of 1.0, 0.5 and 0.25 mg/kg, caused marked decrease of ventilatory response to carbon dioxide in anesthetized dogs. The drug also resulted in mild decrease of total pulmonary resistance, in marked bradycardia and in transient arterial hypotension. These results clearly demonstrate that marijuana can cause depression in the regulation of ventilation. 相似文献
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A theoretical framework on the combined effect of water velocity and solute concentration on the photosynthetic performance of the red alga Gracilaria conferta (Rhodophyta) is developed. This is based on the balance between the rate of transport through boundary layers and Michaelis-Menten-type equations for carbon consumption and for production of oxygen and hydroxyl ions. By comparing the theoretical models with experimental data, we found that the mechanism of enhancing photosynthetic rates by increasing water velocity cannot be attributed to enhanced bicarbonate and CO2 transport, nor to CO2 as a sole source of carbon. Velocity-facilitated photosynthesis may be due to the enhanced removal of OH? ions, which inhibit photosynthesis when accumulated on the algal surface. Oxygen had no inhibitory effect on Gracilaria conferta. 相似文献
505.
Catechol oxidase was purified 330 × from chloroplasts of Clairette grapes. The MW of the enzyme is 80 000 and its Cu content is half an atom per molecule. The amino acid composition of the enzyme is also described. 相似文献
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S Ben Miled D Bibi N Khalfi R Blibech Y Gharbi R Castalli N Khrouf 《Archives de l'Institut Pasteur de Tunis》1989,66(3-4):221-241
This study aims to compare the risk of anemia by iron deficiency in mothers and infants of twin and single pregnancy. It concerned 33 couples of twins and 31 control, all 97 being term newborns. At birth, ferritinemia is significantly lower in twins, and reticulocytes count is significantly higher; their mothers have a significantly lower hemoglobin level and higher reticulocytes percentage and count. At 3 and 6 months, hemoglobin level and mean corpuscular hemoglobin are significantly lower in twins, as at 6 months ferritinemia is significantly lower in twins. Iron stocks constituted in utero are significantly lower in twin pregnancy, and this study support the early preventive iron treatment in twins. 相似文献
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509.
The conversion of 2-ketoglutarate-[14C] to 5-aminolevulinic acid-[14C] (ALA) by a cell-free system from maize leaves is described. Optimal conversion was achieved at pH 6.2 using a 20 000 g supernatant after gel filtration through Sephadex G-25. The formation of ALA required Mg2+, an amino donor (alanine or glutamate), pyridoxal phosphate and NADH. NADPH was somewhat less effective. 相似文献