Male swiss mice were implanted with Ehrlich ascites tumor cells and fed ad libitum either yogurt or yogurt components. Ad libitum feeding of yogurt for 7 consecutive days after tumor implantation significantly (P<0.05) inhibited cell counts by 24 to 28% and DNA synthesis by 23 to 31%. When milk or 1.5% lactic acid was fed, there was no significant effect. Feeding yogurt for 7 d before implantation, in addition to yogurt feeding for 7 d after implantation, did not increase inhibition. The level of inhibition was decreased, however, when feeding was initiated more than 1 d after tumor implantation. While yogurt effectively inhibited initial tumor growth, continuous feeding from day 1 until death had no significant effect on the survival rate of the mice. Centrifugal separation of yogurt into solids and supernatant fluid fractions revealed that the antitumor activity was localized in the solids fraction; the supernatant fluid possessed no activity. Concentration of the solids fraction did not significantly increase the antitumor activity.
In a greenhouse forcing study, root regeneration was correlated with shoot growth, which began with increasing rapidity as chilling requirements were met. Root growth was stimulated by factors originating in the stem of both dormant and growing plants, though root regeneration during physiological dormancy was limited. Auxins applied to decapitated plants stimulated root regeneration while inhibiting shoot growth; gibberellic acid, kinetin, ethylene, and abscisic acid had no direct effect upon root regeneration. The starch content of roots averaged 41% during dormancy, and major hydrolysis of starch was dependent upon initiation of shoot elongation.
Isozyme characteristics were examined for eight enzyme systems in five 50-tree populations of balsam poplar (Populusbalsamifera L.) collected at longitude 90°W, from latitudes 45 to 55°N. Fifty-four percent of the trees were polymorphic at one or more loci, and 8 of the 17 loci examined were polymorphic in one or more populations. Average heterozygosity was low (0.037) and varied little among populations (0.025–0.043). No significant departure of multilocus genotypic proportions from those expected under random mating was observed. Genetic distances and F-statistics indicated that there is little genetic differentiation among populations in terms of the observed enzyme systems.
Broad-sense heritabilities were 0.44 to 0.47 for height, 0.24 to 0.28 for diameter, 0.26 to 0.29 for volume, 0.69 to 0.70 for specific gravity, 0.36 for fiber length, and 0.83 to 0.89 for resistance toMelampsora rust in a breeding population of 100 eastern cottonwood clones from central Mississippi grown for 1 year on Commerce loam and Sharkey clay in 10×10 triple lattice designs.The effect of site was statistically significant for growth andMelampsora rust, but not for wood properties. On the heterogeneous Commerce loam site, the lattice design was more efficient than randomized blocks for evaluating growth but not other characters. Both genetic and phenotypic correlations between characters were low and, with the exception of height x diameter (r p =0.52 to 0.65), of no practical significance in selection. Major variation in form was observed. Large-diameter cuttings elongated significantly faster than small ones through August, after which the effect of cutting diameter was not statistically significant.
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