Ladies and Gentlemen- I notice that some of my thoughts on the above subject found their way to the Purdue Cytometry Mailing List as a result of some off-list exploratory correspondence between me and Jan Nicholson at CDC. While I hadn't intended to go public on this issue quite so soon, I will now do so. The pace of development of instruments, reagents, and techniques optimized for cytometry of microorganisms - in which category I will include bacteria, nano- and picoplankton, fungi, viruses, and unicellular eukaryotes - has been glacial. For example: My colleagues and I published the first paper on flow cytometric detection of single viruses (using scatter signals in a laboratory-built instrument) in 1979, and, while Harald Steen reproduced those results within a few years, the next published paper on detection of single viruses (using nucleic acid dye fluorescence in a commercial benchtop instrument) appeared in 1999. No current commercial instrument has sufficient sensitivity to make precise multiparameter measurements of substances present at levels below a few thousand molecules in individual microorganisms. It's not that it is that hard to do, but it can't readily be done on apparatus designed for analyzing eukaryotic cells. One size does not fit all. Furthermore, bacteria are not just little eukaryotes. Many of the dyes with which we have become familiar as stains for eukaryotic cells behave differently in bacteria; some behave differently in different bacterial species. Relatively few monoclonal antibodies against microbial antigens are commercially available, and most of those are available either unlabeled or with the choice of label limited to fluorescein. Other specific reagents, e.g., rRNA probes, are also difficult to find. The immunologists and hematologists - even the most competitive ones - have cooperated over a generation to define the CD antigens, antibodies to which have become profitable for a number of companies; a similar cooperative effort will have to be undertaken to make better reagents available for microbiology. It's not that there aren't a reasonable number of people who want and could benefit from improved instruments, reagents, and techniques for cytometry of microorganisms; the obstacle appears to be something like an activation energy barrier. In a word, the development process needs to be catalyzed; I am volunteering to be one of the enzymes. I propose to establish and direct a Center for Microbial Cytometry. The first mission of the center will be to get interested parties (from academia, government, and industry) together, by e-mail at first and by conference call or face-to-face meeting as appropriate later, to define (and catalog) the principal problems and currently available solutions. We can expect to find that, in many cases, one group of investigators has some solutions to another group's problems, which should lead to productive collaborations. Ideally, this would increase manufacturers' level of interest in providing the needed systems and materials, but, if it did not, we would at least have a data base and a clearing house that would facilitate do-it-yourself instrument modification and construction and exchange of reagents and techniques. I don't expect the Center to accumulate a large staff and a building full of labs; we would only need people and resources on-site to do what none of our participating members was willing or able to do. I therefore also don't expect a large budget to be required, and it seems to me that the necessary funds could be obtained from some combination of government agencies, private foundations, and/or industrial donors. I can't promise to answer every e-mail I get back on this subject, but, if you are interested, please do send something to me personally (hms@shapirolab.com) so I can compile a mailing list. If you know someone else who might be interested, forward the message to him or her. While the Cytometry Mailing List is a suitable forum for some further discussion on this subject, please *don't* copy or post simple correspondence or forwards to the List. You will also note that this posting is addressed to the Cytometry Mailing List and not to a long list of people I know are interested in microbial cytometry, which includes many subscribers to the Cytometry Mailing List. I'll get something out to my "Microbiology List" people within a few days. Thanks for your attention. -Howard
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