A study of the Project for American Studies in the Secondary Schools and its effect on curricular change

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McNierney, Donna J.
Reak, Jack
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Thesis (D. Ed.)
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The purposes of this study were to determine the effect of the exogenous polyamines, spermidine and spermidine, on growth of crown gall tumors, to assay levels of spermidine and spermine in normal and crown gall tumor tissue and to determine the effects of selected anti-tumor compounds on growth of crown gall tumors as well as on the endogenous levels of the polyamines in those tumors.Findings1. Spermidine and spermine are present in normal potato tissue and crown gall tumor tissue grown on potato discs.2. Exogenous spermidine and spermine do affect growth of crown gall tumors depending upon the concentration of the solutions added, the type of polyamine added and the number of times the solutions are applied.3. Spermidine (1 mM) has a positive growth effect on crown gall tumors.4. Crown gall tumor tissue contains more spermidine than corresponding normal potato tissue; spermine levels are consistently low compared to spermidine levels in both crown gall tissue and normal potato tissue.5. The level of spermidine in tumor tissue increases as the tumors develop; the level of spermine remains consistently low.6. Addition of methylglyoxal bis (guanylyhdrazone) inhibits tumor growth, but the inhibitory effect is decreased by concurrent administration of spermidine.7. Both novobiocin and nalidixic acid have an inhibitory effect on tumor growth, but the effects are decreased by concurrent administration of spermidine. Reversal of the nalidixic acid effect on growth by addition of spermidine is more pronounced than reversal of the novobiocin effect.8. Methylglyoxal bis (guanylhydrazone) decreases the endogenous levels of both spermidine and spermine in crown gall tumor tissue.Conclusions1. The polyamine, spermidine, plays an important role in the growth of crown gall tumors.2. Compounds which inhibit spermidine biosynthesis or the possible mode of action of spermidine inhibit tumor growth.3. Other polyamines appear to have no significant role in crown gall tumor growth.4. The growth of crown gall tumors involves the activation of a mechanism leading to the increased biosynthesis of spermidine.5. A specific inhibitor of polyamine biosynthesis in animals also reduces endogenous levels of spermidine and spermine in crown gall tumors.6. These data further support the hypothesis that crown gall tumors are similar to animal tumors.