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991.
Nucleoside transport in sheep erythrocytes is under the genetic control of two allelomorphic genes (Nu I and Nu i ), where Nu I codes for the functional absence of a high-affinity nucleoside transport system and is dominant to the gene (Nu i ) coding for the presence of the transport system. Kinetic and inhibitor experiments show that the high-affinity transport system is not present in heterozygous erythrocytes, demonstrating that the Nu I gene is completely dominant over the Nu i gene. It is suggested that the Nu locus may not represent the structural gene locus of the nucleoside transport system. Instead, it may be a regulator gene locus. 相似文献
992.
Grouping of Lactic Streptococci by Gel Electrophoresis of Soluble Cell Extracts 总被引:8,自引:3,他引:5
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Soluble cell proteins obtained from 35 strains of lactic streptococci were examined by gel electrophoresis. A mathematical analysis of the densitometer scans of the gels enabled strains to be grouped according to their overall similarity. Strains which were known to be variants of the same parent strain fell into the same group, supporting the validity of the method. It is suggested that strains which are alike according to their gel electrophoretic patterns when grown under standard conditions have an overall phenotypic similarity and that this indicates a similarity in genotype. The relevance of this to selection of strains of lactic streptococci for cheesemaking is discussed. 相似文献
993.
Uptake and transport of lead by perennial ryegrass from flowing solution culture with a controlled concentration of lead 总被引:1,自引:1,他引:0
Summary Perennial ryegrass was grown in flowing solution culture in a glasshouse, and during February lead was added to the nutrient
solution and held at a constant concentration; uptake and transport of lead were followed in conditions of low intensity daylight
or higher intensity artificial light. Uptake of lead by the roots was most rapid during the first 4 days after addition to
the nutrient solution. After this time there was a steady increase in uptake per g dry weight of root with plants grown in
artificial light having a much higher rate of uptake than plants grown in daylight. Roots always contained more lead than
the corresponding shoots and concentration was always greater in the roots than in the shoots. The concentration in both roots
and shoots increased with time but that in plants grown in artificial light was higher than that in plants grown in daylight.
Two phases of uptake were identified, an initial rapid phase which is probably an exchange phenomenon, and a slow sustained
phase which may be under metabolic control. A lower proportion of the total lead taken up remained in the roots of plants
grown in artificial light than in those grown in daylight. This difference may have resulted from differences in (i) the production
of organic carriers and/or (ii) transpiration. re]19750930 相似文献
994.
ON TWO NEW MEMBERS OF THE VOLVOCACEÆ 总被引:1,自引:1,他引:0
995.
OOGENESIS AND EMBRYOGENY IN EPHEDRA DISTACHYA. 总被引:1,自引:1,他引:0
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