Frequency and orientation of pseudopod formation ofDictyostelium discoideumamebae chemotaxing in a spatial gradient: Further evidence for a temporal mechanism

摘要

AbstractAmebae ofDictyostelium discoideumnormally chemotax to aggregation centers by assessing the direction of outwardly moving, nondissipating waves of the chemoattractant cAMP. However,D. discoideumamebae can also assess the direction of a relatively stable spatial gradient. We demonstrate that amebae migrating towards the “source” of a stable, spatial gradient move faster, extend fewer pseudopodia, and turn less frequently than amebae migrating away from the “source” in the same spatial gradient. In addition, amebae extend lateral pseudopods in a polarized fashion from the anterior half of the cell, and do so as frequently towards the source as away from the source. However, those formed towards the source more often produce a turn than those formed away from the source. These results suggest that there may be two decision‐making systems, one localized in the pseudopods, and one along the entire cell body; they support the suggestion thatDictyosteliumamebae may employ a temporal mechanism to assess the direction of a spatial gradient of chemoa