by Elio
If before 1950 you had asked "are bacteria cells?" the chances are that you would be told "it depends…"In other words, no one knew for sure. It took Joshua Lederberg, who, upon discovering mating in E. coli,proposed that bacteria were indeed cells. In time, two researchers, both in the microbiology department at the University of Pennsylvania, thought that if bacteria were cells, they should indeed have the attributes of cells. Stuart Mudd proclaimed that bacteria contain mitochondria, Edward DeLamater that they havenuclei that divide by mitosis. They argued their views emphatically, provoking intense and colorfuldebates with non-believers. The "cytology" sessions at the annual ASM meeting were always well attended, notably by those who liked to listen to a good and loud fight.
Fig. 1. Light microscopy images of tetrazolium-stained Mycobacterium tuberculosis. The stained spots were interpreted as evidence for mitochondria in bacteria. Source.
The Penn micro department at the time was so controversial that when I told a student from some otherdepartment that I was grad student there, he said: "Fancy admitting it!" But, being part of a major university, some of my fellow grad students were superb and went on to do fine things (one example isthe famed bacterial geneticist Phil Hartman, with whom I was lucky to share an apartment).
I did my Ph.D. under DeLamater, although not by choice. Lucky for me, I was put to work on the cytology of the alga Chlamydomonas, not on bacteria. But I was there when it all happened, so let me try to explain the basis for these beliefs. Mudd's lab used a type of tetrazolium compound that turns into an insoluble red upon reduction. In higher cells, tetrazolium stains their mitochondria, ergo, he argued, the little bodies so stained in bacteria must be the equivalent of these organelles. In those days, ultrathin electron microscope sectioning had not yet been developed for bacteria. It would have quickly revealed that the stained material consisted not of organelles but of amorphous blobs, eventually called "inclusion bodies." I don't think that the "mitochondria" idea became particularly popular, and I reckoned that it simply waned away. Dr. Mudd was quite old by then and soon died. Nobody that I know of took up thisparticular cudgel.
On the other hand, DeLamater was younger and hale and spoiling for a fight. He had based his assertion for mitosis on microscopic observation of bacteria treated with a modification of the classical Feulgenreaction, which stains chromosomes. He examined such preparations of bacteria, squashing some by pressing on a cover glass with the rubber tip of a pencil. Pretty soon, he found shapes that he interpreted as being the various stages of mitosis. Some looked like chromosomes in metaphase, others in telophase, etc. And therein laid the fight, as others – notably K. Bisset and C. Robinow – vehemently disagreed. The heated discussions, which went to for several years, were held at meetings as well as in print. But the story has an unexpected end. Out of the blue, DeLamater published a note – in Nature no less – recanting his claim for mitosis in bacteria. He explained that the microscopy available at the timedid not permit sufficient resolution for his conclusions. Caramba! This is quite an admission, considering how important the subject had been for him. If you want to read about the current state of affairs in this subject, see here.
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