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Keywords:

  • Chara corallina;
  • Charophyta;
  • plasmodesmata;
  • transnodal fluxes;
  • transnodal resistance;
  • plasmodesmata

ABSTRACT

The permeability of plasmodesmata in the nodal complex of branch cells of Chara corallina was examined by measuring both the transnodal electrical resistance and transnodal fluxes of 36CI and 14C-buty-rate. Under normal circumstances, the resistance across the node was low, but increased rapidly in response to metabolic inhibition, pressure gradients across the node or excision of one of the cells. For each of these treatments, there was a substantial reduction in solute transport between the cells. Acidification of the cytoplasm by weak acids or alkalinization by amines did not affect either the electrical resistance or the flux of solutes through the node between whorl cells. The transnodal resistance was significantly higher in older cell pairs, but was unaffected by large transnodal voltage differences or by the passage of action potentials. There was no evidence that short-term increases in cytoplasmic calcium have any effect on plasmodesmatal permeability.