A.R. Gray
When I was asked to say a few words of welcome and introduction to this meeting on genetic exchange in trypanosomes, I found it very easy to accept because I find myself repeatedly marvelling at the sudden burst of activity and progress in an area which has been a nagging problem for protozoologists for so many years. When I joined my first protozoology research institute in West Africa in the late 1950s, my colleagues there, Desowitz, Williamson, Stephen and Godfrey (to say nothing of Bill Trager who was visiting), were even then racking their brains as to how to get at the trypanosome chromosomes or whatever the organisms used to regulate and perpetuate their existence. Godfrey was forever citing Wolbach and Bingham who had reported a complement of three chromosomes visualized by traditional cytochemical methods about 1910, and Williamson was soon to start work with Amrein and Fulton which failed to demonstrate exchange of genetic material between drug resistant and sensitive trypanosomes. These far-sighted scientists recognized, even then, the importance of more knowledge in this area.
We have had to wait 20 years until the 1980s when suddenly the techniques of enzymology, molecular biology, biophysics and electron microscopy have been combined and allowed us to look directly into the composition and function of the trypanosome genome. Within the space of 5 years, we have had reports of exchange of genetic material between trypanosomes from examinations of naturally occurring and laboratory-generated materials, direct measurements of the nucleic acid content of individual parasites, the first description of DNA organized as minichromosomes, the separation and visualization of chromosomes of different sizes and classes by pulsed-field gradient gel electrophoresis (PFG) and orthogonal-field alternation gel electrophoresis (OFAGE), to say nothing of genes for every job! A year ago, I was privileged to sea a scientist in Belgium painstakingly counting chromosomes by drawing condensations of chromatin possibly representing junctions in photographs of serial EM sections of trypanosome nuclei. The progress is fantastic! Some mild confusion and uncertainty is understandable.
Now, this is not a research area where ILRAD has played a major role or where we have particularly special expertise, except perhaps in some of the molecular biology and aspects of parasite transmission, but it is an area in which we have to be very interested, since recombination events have major implications for immunization, parasite identification and speciation, and chemotherapeutic programs.
When Dr. Doyle and I were considering possible topics for seminars and workshops at ILRAD last October, genetic exchange in trypanosomes came naturally to mind, but I do not think either of us had any idea that the eventual timing of the workshop would be so appropriate. It follows closely on the publication of a major work on the topic by Professor Jenni and colleagues. Controversy is rife about the mechanism and the site of exchange in fly or mammal is open to informed and uninformed speculation. It is little wonder that Professor Vickerman has said that it is high time somebody set down the incontrovertible evidence for six in trypanosomes in black and white.
This meeting has rather optimistically been called a workshop, but I doubt if it is going to be a real workshop as defined in current scientific understanding. I think you can hold a conventional workshop when there is a body of background information on a subject, when there are recent new findings to consider, and when there is a firm idea of a relevant objective. In this situation, a workshop can indicate the appropriate path to achieve the objective.
The situation we are considering here is more diffuse and we have no rigorously defined objectives. The meeting has therefore been organized as a small conference with a number of aims which can be summarized as follows:
I hope there will be brief addresses, active discussions and just a little writing to provide a record of the meeting.
I now offer my thanks to John Young and Jim Lenahan and the Organizing Committee who have done most of the work so far and my encouragement to the chairpersons, speakers and rapporteurs who must now take over. I wish you all a useful and successful meeting and, to those from overseas, an enjoyable visit to Kenya.
