Flames. If you were to spontaneously quote a biological instrument, it would undoubtedly be a microscope. And in fact, researchers in biology are both observers and experimenters: they observe, question, formulate hypotheses, then apply themselves to testing them … In an incessant back-and-forth, they release models, deductions and knowledge.
The line between observation and experience, however, is not always as clear as that drawn in 1765 in the article “Observation” by The encyclopedia : “Astronomers’ glasses, the Naturalist’s magnifying glass, the Physicist’s microscope do not prevent the knowledge which one acquires by this means from being exactly the product of observation: all these preparations, these instruments are only useful. make the different objects of observation more sensitive (…) ; But (…) he does not leave an appearance as it is; & It is mainly in this that the observation differs from the experience which decomposes & combines, & thereby gives rise to phenomena quite different from those which nature presents “.
Anachronistically, one would sometimes like to ask the author of these lines for his opinion on today’s microscopy; because current methods often interfere with the observed phenomenon, which should be evaluated and taken into account before drawing any conclusions.
Choice of probes
Foremost among the disturbances induced by observation: light. Thus, when we observe the multiplication of bacteria under a microscope, it is slowed down for some species, accelerated for others, under the very effect of the illumination necessary to see them. Moreover, to observe cellular constituents, magnifying the image of a cell is not enough; the preparation for “Make the different objects of observation more sensitive” This often makes the observation indirect: we mark the object that interests us, usually with a fluorescent compound that serves as a reporter of what we want to detect. We still have to make sure that this rapporteur reveals what we believe. Finally, the rapporteur himself is likely to modify what is observed.
Two articles published in April in Structure and in July in The EMBO Journal judiciously remind us that this technical pitfall is encountered during the microscopic observation of actin filaments in living cells. The filaments belong to the cytoskeleton: like a skeleton, they structure the morphology of each cell and, by coordinating their movements with respect to each other, participate in its movements. Each filament is made up of units that come together at one end, break off at the other, leading to the overall displacement of the structure.
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