11] Necrotaxis and galvanotaxis

Abstract

In vitro experiments can be used to investigate the responses involved in chemotaxis, galvanotaxis, and necrotaxis. For experimental purposes, necrotaxis and galvanotaxis present several advantages: (1) measurements are very reproducible, (2) directed and nondirected locomotion can be investigated before and after lysis of the target cell in a necrotactic assay and before and after applying the electric field in a galvanotactic assay, and (3) response of cells to external factors can be determined as a function of time. There are also disadvantages associated with necrotaxis: the external factors are unknown and the magnitude of the external factors is a function of both time and space. The necrotactic or galvanotactic response of locomoting cells can be described mathematically to obtain information about the cellular response. It might initially seem that necrotactic assays are disadvantageous, because they are both time and space dependent. However, because the dependence of the polar order parameter on the strength of the polar field can be seen in a single experiment, this also represents an advantage. The polar order parameter is large in the vicinity of the lysed cell and decreases as the distance from the cell increases.