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I. Chemical Study of Necrotic Com Mutants. II. The Metabolism of a Kinin. III. The Chemical Nature of an Insect Gall Growth Factor


McCalla, Dennis Robert (1961) I. Chemical Study of Necrotic Com Mutants. II. The Metabolism of a Kinin. III. The Chemical Nature of an Insect Gall Growth Factor. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/ZQ00-1H14.


Part I: The leaves of nec rd (a single gene necrotic maize mutant) become necrotic when they are exposed to light for a few days. Extensive analysis has failed to reveal any difference in chemical composition between leaves of normal plants and of homozygous nec rd plants before any necrotic symptoms are visible (prenecrotic leaves). Treatment of nec rd seedlings with various metabolites (B vitamins, purines, pyrimidines, amino acids, etc.) did not prevent the appearance of necrosis. The rate of photosynthesis of prenecrotic leaves is normal at low light intensities but 20 to 50% of normal at saturating light intensity. C14O2 feeding experiments indicate that the carbon fixing reactions function normally in the mutant. Hill reaction rates are also similar in mutant and normal plants, as is the metabolism of labelled inorganic phosphate. CMU, which specifically inhibits photosynthesis to the extent of about 90%, delays the onset of visible necrotic damage and reduces the severity of subsequent necrotic symptoms. It is suggested that the nec rd lesion is in some reaction associated with photosynthesis and that it causes the accumulation of one or more toxic substances. These lower rate of photosynthesis and damage cell membranes. The necrotic phenotype would appear to be the result of the breakdown of cell compartmentalization. Part II: The kinin, 6-benzylaminopurine (benzyladenine), is converted to a number of low molecular weight materials by senescing leaves of Xanthium pensylvanicum Wall.(cocklebur). A major product is the riboside, benzyladenosine, which has been identified by comparison of its properties with those of benzyladenylic synthesized enzymatically using E. coli nucleoside phosphorylase and by degradative studies. The ribotide, benzyladenylic acid, also appears to be present. Labelled adenylic, guanylic and inosinic acids are produced, as are small amounts of adenine and guanine. Substantial amounts of label are also found in urea and in a ureide. Small amounts of labelled adenylic and guanylic acids are found in the RNA of the leaf, but benzyladenylic acid itself does not appear to be incorporated into RNA in measurable amounts. Part III: Low molecular weight material obtained from excised accessory glands of Pontania pacifica (gall-wasp) promotes the growth of Pontania galls on Salix alba (willow). Paper chromatographic analysis has indicated that uridine, uric acid and two unidentified adenine containing compounds are prominent constituents of this mixture. Uric acid and the two adenine containing compounds substantially increase the growth rate of small galls from which the larva has been removed while uridine has slight growth promoting activity. Various related compounds (e.g. adenosine, adenine and guanosine) also have growth-promoting activity. It appears likely that such compounds play an important role in the growth and development of Pontania galls.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:(Biochemistry and Genetics)
Degree Grantor:California Institute of Technology
Major Option:Biochemistry
Minor Option:Biology
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Bonner, James Frederick
Thesis Committee:
  • Unknown, Unknown
Defense Date:1 January 1961
Record Number:CaltechETD:etd-04102006-135936
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:1327
Deposited By: Imported from ETD-db
Deposited On:11 Apr 2006
Last Modified:21 Nov 2023 17:29

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