The effect of p-chloromercuribenzoate on rotational protoplasmic streaming in plant cells

Abstract

(1) The effect of p-chloromercuribenzoate (PCMB), a highly specific sulfhydryl reagent, on the rotational protoplasmic streaming in plant cells was studied. Materials used were; internodal cells ofNitella flexilis, leaf cells ofElodea densa, root hair cells ofHydrocharis Morsus ranae and stamen hair cells ofTradescantia reflexa. (2) The response of the rotational protoplasmic streaming to PCMB were all alike in these plant cells: First, streaming was retarded and ceased within a short time with PCMB in a suitable concentration; second, streaming was restored completely or fairly well through subsequent application of cysteine at a concentration higher than that of PCMB; third, when its activity to block -SH groups was eliminated with cysteine in advance. PCMB exerted no effect on the streaming. (3) As it is well known that PCMB is bound to -SH groups with high specificity, it is reasonable to conclude that the cessation and recovery of streaming are closely related to the blocking and liberation of -SH groups in the protoplasm. (4) Specificity of the action of PCMB for -SH groups was further confirmed through the application of L-serine, HOCH2·CH(NH2)·COOH against L-cysteine, HSCH2·CH(NH2)·COOH. (5) Though found only once, reversal of the streaming direction was observed in an internodal cell ofNitella.