Effects of Calcium and Potassium Ions on Phototaxis in Cryptomonas

Effects on positive phototaxis and the cell motility of 7 cationsin 5mM MOPS (morpholinopropane sulfonic acid) buffer (pH 7.0)containing 0.16 mM NaCl, 0.68 mM KCl, 0.5 mM CaCl₂ and 0.16mM MgCl₂ were studied in the unicellular flagellate Cryptomonaswith a photoelectrical measuring apparatus and photomicrography.When calcium ion was removed from the medium by adding 1 mMEGTA (ethylene glycol-bis-(ß-amino-ethylether)-N,N'-tetraaceticacid), the phototactic response was totally inhibited, but theswimming rate was not much affected. The effect of EGTA waspartially reversed by the addition of 1 mM CaCl₂. When 15mMKCl or RbCl was added to the medium, phototaxis was greatlyinhibited, but there was no significant influence on the swimmingrate. Similar but less inhibitory effects were induced in thepresence of NaCl, LiCl and CsCl. KCl-induced inhibition waspartially removed by the addition of 15 mM CaCl₂ or MgCl₂. (Received June 25, 1982; Accepted September 27, 1982)     

Effects of viscosity on phototactic movement and period of cell rotation in Cryptomonas sp.

The "protective" effect of polyamines and related metabolites on wounded storage tissues was investigated in two experimental systems: RNase activity of potato ( Solanum tuberosum L.) tuber discs, and betacyanin leakage from beet root ( Beta vulgaris L.) discs. Potato tuber discs evince a dramatic rise in RNase activity 24 h after excision, and this rise is completely blocked by the polyamines, spermidine and spermine. The effect is concentration-dependent, and several precursors of polyamines are also effective to various degrees in inhibiting the rise in RNase activity. Polyamines inhibit both the wound-induced RNase and the rise in RNase activity which may result from other senescence-linked events. Betacyanin leakage from beet root discs is enhanced upon aging of discs and in response to various treatments which may cause membrane damage. Spermidine and spermine effectively inhibit betacyanin leakage which results from aging at 25°C, from incubation at higher temperatures (35–40°C), from freezing of discs, or from treatment of discs with RNase or protease. It is suggested that polyamines decrease RNase activity and solute leakage in sliced storage tissues by affecting primary wound-induced destabilization of cell membranes.