Comparative microphotometric studies of DNA and arginine in plant nuclei

Summary Photometric measurements have been made of the amounts of stain formed in the Feulgen (DNA) and Sakaguchi (arginine) reactions in plant nuclei of differing ploidy.In nuclei of diploid and tetraploid plants of Tradescantia ohioensis and of diploid, triploid and tetraploid plants of Ranunculus ficaria, both Feulgen and Sakaguchi values gave ratios which agreed closely with the ratios of the number of chromatids known to be present. The Feulgen/ Sakaguchi ratio for each of the different types of nuclei measured was very similar both within and between these two species.In the interphase nuclei of five different species, both Feulgen and Sakaguchi values gave bimodal distributions. In the nuclei of differentiating cells, the proportions of values falling into each of the 2C, 4C or 8C classes were the same for both stains.Measurements of the amounts of both stains were made in sequence on the same individual nuclei and a positive correlation found between the two sets of values.In nuclei from differentiating cells of Vicia faba primary roots, the Feulgen/Sakaguchi ratio decreased with increasing distance from the apex.The following suggestions were made from the results: (a) that there is some degree of quantitative constancy of nuclear arginine which parallels that of DNA; (b) that the amount of nuclear arginine, like that of DNA, is doubled during synthesis in interphase; (c) that the syntheses of DNA and arginine in interphase, if not simultaneous, at least occur within the same relatively short period; (d) that there may be a difference in the DNA/arginine ratio between the nuclei of meristematic and differentiating cells.     

Observations on the seasonal incidence of microsporidiosis in European corn borer populations in Illinois

Summary Examinations of living and dead larvalPyrausta nubilalis (Hübner) collected in the field over a four-year period indicate that infections caused byPerezia pyraustae Paillot are widely distributed within populations ofP. nubilalis in Illinois. Observed fluctuations in the incidence of the parasite among living and dead insects collected in various seasons was taken as evidence that the disease interacts with temperature to cause mortality in populations of the host.

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Résumé Des examens des larves vivantes et mortes dePyrausta nubilalis (Hübner) collectées dans les champs pendant quatre années consécutives indiquent que des infections parPerezia pyraustae Paillot sont très fréquentes dans les populations deP. nubilalis en Illinois (états-Unis). Les fluctuations observées dans l'incidence du parasite dans les insectes vivants et morts recueillis pendant plusieurs saisons montrent que la maladie est influencée par la température, celle-ci occasionnant la mortalité dans les populations de l'h?te.

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An abridgment of a portion of a thesis submitted in partial fulfillment of the requirements for the degree Doctor of Philosophy in the Graduate College of the University of Illinois, 1958.