Visiting Professor Home Page

1) Hereditary Concepts: What Are They and How Were They Discovered?
Genetic concepts have evolved over a long period of time. Though we begin modern genetics with the experiments of Gregor Mendel, there must have been questions about heredity before that time. How did early humans consider the variation that was observed? What were the concepts associated with the diversity in nature? Prior to Darwin , there was a general consensus that there was a design by the almighty for this variation. But, Darwin was convinced that living things evolve by natural selection. That is how the diversity arises. But since Mendel, heredity became particulate, not blending. It only remained for further discoveries to provide an explanation of the predictability of heredity. Many discoveries followed that included chromosome relations, genetic exchange to the discovery of DNA as the hereditary determiner. But, what followed in the next decades to today is still more remarkable. This presentation will provide a survey of genetic discoveries that lead to DNA as the basis of heredity.

2) The Corn Plant: “A Symphony of Hormonal Control”
The corn plant, like a conductor of a symphony orchestra directing various instruments, including the violins, cellos, trombones, and other players of the orchestra, also directs the synchronous development of its various parts. Most everyone has noticed the growing corn plant as the corn tassels emerge in early July, followed by the falling yellow pollen from the shedding tassel. Soon after, or almost synchronously, the growing ear shoot emerges, showing the issuing yellow-green silk. What signal is sent to the ear to emerge only after the tassel begins developing? Is the signal a hormone? The ear shoot appears at approximately the 10 th leaf and not higher, which might puzzle the observer. And the silk “waits” for the tassel to begin shedding pollen, almost never silking sooner. And, when the pollen ceases shedding, the silks are no longer receptive and no longer capable of receiving pollen. This illustrates the striking developmental control of the “signals” in the corn plant. These hormonal signals clearly program the development of plant organs. The understanding of this “symphony” will provide an insight into signaling phenomena and the implications of these phenomena for bioengineering

3) Transposons or Mobile DNA in Corn Populations: How Does This Relate to the Human Genome?
Striking sectoring of red stripes on a yellow background of flowers and the multi-sectored corn ears found in the fall are signs that transposons are “actively jumping” in these plants. Transposons, discovered by Barbara McClintock (who won a Nobel Prize in Medicine for this discovery), are DNA segments that are mobile from one chromosomal position to another position. The discovery of transposons is the most episodic event for plants in this century. That they have survived in corn populations is a mystery. Yet, there is reason to believe these transposons aid and abet the production of diversity among plants, leading to their survival. But how universal are these elements and what do they do in the genomes? And, what is happening in the human genome? What is particularly striking in the human genome and is there a relation to maize?