Chemotaxis positive

Using gloves and forceps, place the polycarbonate filter over the chemokine- or medium-filled wells of the chamber. Adjust the position of the filter if the peripheral wells are not covered. Over adjustment of the filter may result in crosscontamination of the wells in the chamber. The chamber gasket and lid should be assembled quickly after the placement of the filter. Pressure should be applied to the center and the comers of the chemotaxis chamber lid prior to final chamber assembly to prevent cross-contamination and bubble formation. 

Chemotaxis was performed using 96-well chemotaxis plates employing 8 p,m filters. Thirty microliters of chemoattractant supplemented with various concentrations of selected experimental agents or vehicle was added to the lower wells of the plate in triplicate. The filter was positioned on top and 25 jxl of cells preincubated with a selected concentration of an experimental agent or vehicle added to the surface of the filter. The plate was incubated 2 hours at 37°C in a humidified C02 incubator, the remaining cells on the surface were removed by adsorption, and the entire plate centrifuged. The filter was then removed and the cells that had migrated to the lower wells were quantified by cell fluorescence of associated calcein-AM. 

Photomovement as a tool to locate optimal conditions for photosynthesis is not the only tactic behaviour halobacteria can master. The cells respond to many more positive and negative stimuli than light alone. Examples found are chemotaxis, aerotaxis and, presumably, thermotaxis. All the signal chains initiated by the activation of various receptors of the cell merge into one and the same final target, the flagellar motor. 

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