Effect of osmotic pressure, ionic imbalance, and pH upon the regeneration rate in Blepharisma

Abstract

1. 1. Regeneration of Blepharisma occurs at about the same rate as in unit standard balanced salt solution (USBSS) (4.35 × 10 −3 osmolal) when the concentration is 2 ×, 8 ×, or 12 × this amount. When increased to 20 × USBSS there is a delay of about 7 hr, and at 24 × USBSS regeneration is very much retarded. 2. 2. Not only is regeneration of Blepharisma placed in balanced salt solution of increased concentration retarded, but some cells die, the number dying increasing with the salt concentration. 3. 3. Sucrose solutions are about as injurious to regeneration of Blepharisma as balanced salt solutions of equal osmolality. 4. 4. It is quite evident that in higher concentrations of balanced salt or sucrose solutions blepharismas lose water rapidly, shrinking to flat leaflife forms. If they recover they later take in some water. 5. 5. NaCl and KCl solutions block regeneration at lower osmolal concentrations than balanced salt solution, KCl of a given concentration being more effective than NaCl. 6. 6. In solutions of EDTA of concentration enough to chelate all the calcium and magnesium, regeneration is normal. When the concentration of EDTA is doubled, regeneration is retarded and many blepharismas remaining in the solution overnight disintegrate. In 4 × unit EDTA all blepharismas die almost immediately. 7. 7. Blepharismas in lower concentrations of sucrose are not more sensitive to UV than controls. They become much more sensitive to UV at the sucrose concentration at which sucrose stress is evident in unirradiated cells. 8. 8. Regeneration of Blepharisma is not retarded by pH of balanced salt solutions over the span 5.5 to 7.7. At pH 4.7 regeneration is retarded for several hours. 9. 9. It is postulated that external application of concentrated solutions of salts or sucrose to blepharismas injure them by withdrawal of water. This concentrates the internal salts of the cell, a process known to be injurious to enzymes of the cell responsible for life processes.