Date of Award
Life & Environmental Sciences
Rev. Joseph Harrington
Rev. John Redman
The search to conquer cancer is a powerful goal, unifying people of all fields of endeavor. The cells of cancerous tissues have often been described as anarchists in a well organized state. ''Normal cells live in fixed relation to their neighbors, strictly obeying the laws of their society. They grow in an orderly way, under rigid control to a definite end (Braun 1952).” On the other hand, the growth of tumor cells is unorganized, independent, and without relation to the needs of the community. The tumorous growths referred to as crown gall in plants, is analogous on the cellular level to malignant animal tumors. Cancer in animals, including humans, often results from chemical irritation to tissues, or perhaps from viral infection. In plants the causative agent of cancer is a bacterium, Agrobacterium tumefaciens, commonly referred to as the crown gall bacterium. Crown gall, like animal cancer, shows two basic characteristics J: abnormal growth into unorganized and undifferentiated tissue - hyperplastic tumor; and analogous to metastasis, the formation of secondary bacteria free tumors at different locations farther up on the plant. These bacteria free tumors indicate that it is not the bacteria themselves that cause crown gall, but some inducing principle or interaction. Though crown gall is a common disease of orchards in the midwest, the purpose of this research is not to find a "cure,1’ but to gain insight into the cancer problem at the cellular level; to understand the striking, permenent alteration of the morphogenlc potential by an unknown inducing principle associated with Agrobacterlum tumefaciens That is, there is a change in the normal pattern of development of form and structure (ontogeny), causing the once normal cell to multiply abnormally into massive, disorganized tumor tissue. For instance, when the tumor inducing principle associated with the crown gall bacterium acts on the cells of a plant species such as Helianthus annuus, the Giant Russian Sunflower, an abrupt and irreversible change in the behavior of these cells occurs. Following the transformation process, proliferation of the altered host cells becomes an automatic process that is independent of the insighting bacteria. The cells of the resulting neoplasm are characterized by excessive proliferation and limited differentiation. As a result of the inducing principle, organizational competence is completely lost. Because crown gall is an excellent material for in vivo and in vitro experimentation, it is a valuable tool for the study of abnormal growth. The experiments that follow have shed much light on the immensity and nature of the cancer problem for me and hopefully for the reader. The common denominator of all cancers, despite the primary causative agent, whether smoking or Agrobacterium, is to be found on the level of the cell through an understanding of Its Individual Identity and community interaction. The research, bibliographical and experimental, presented here is in three parts. I. The Action of Penicillin on the Growth of Agrobacterium tumefaclens in Vitro II. The Action of Penicillin on Crown Gall in Vivo III. The Action of Penicillin on Bacteria-Free, Secondary Crown Gall Tumors in Tissue Culture
Doyle, Kathleen, "Effect Of Penicillin On The Crown Gall Tumor-Inducing Principle In Helianthus Annuus" (1970). Life and Environmental Sciences Undergraduate Theses. 534.