Characterization of Chemotactic Selection


    Specific, ligand-receptor interactions of chemotaxis are used to select subpopulations of cells possessing high chemotactic responsiveness. This novel technique - described by our group - is available for isolation of subpopulations with high chemotactic responsiveness and provides the theoretical possibility to analyse receptor dynamics in the offspring generations (Kõhidai and Csaba, Cytokine, 10: 481, 1998)


Scheme of chemotactic selection    

After the first chemotaxis assay the selected group of these responsive cells are cultured in neutral environment, containing no selector ligand for relatively long periods up to the cell-cycle of the investigated cell type. In Tetrahymena by the end of the one week culturing with consecutive transfers, about 70th generation of the starter cells are available. At that time we can evaluate the durability of the ligand related receptors by repeated chemotaxis assays.





Membrane dynamics of chemotactic selection

Combinations of testing the selected and non-selected (control) cells with selector or reference ligands provides information about whether the receptors triggered by the tested chemoattractant ligand have short- or long-term dynamics in the investigated system. Both signaling backgrounds are theoretically conceivable: presence of the chemotactic ligand might induce an ad hoc,  transient assembly of receptor components (short-term responsiveness) as well as the whole complexes might be present as genetically determined components of the membrane (long-term responsiveness). In the second case the chemotactic responsiveness is more durable and we can get increased chemotactic responses by consecutive chemotactic selections (Kõhidai et al. 2000).



    Hypothetical scheme of receptor dynamics of short- and long-term chemotactic responsiveness. In short-term responsiveness ad hoc components of the membrane are assambled for a transient period and disassembled following the release the ligand, while in the ‘long-term’ type constitutive complexes of the membrane are working as chemotaxis receptors.