Ref ID : 3945
Robert D. Hinrichsen; An Analysis of Specific Temperature Blocks in the Conjugation Sequence of Paramecium tetraurelia. J.Protozool. 28(4):417-423, 1981
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Temperature shifts have been used to block critical points in the conjugation sequence of Paramecium tetraurelia. Increasing temperatures above 27 degrees C reduced ciliary agglutination, pair formation, and nuclear exchange; a complete inhibition of these stages occurred at 37 degrees C. Temperature below 19 degrees C had no effect on ciliary agglutination or nuclear exchange but completely inhibited pair formation. The bases for the cells' inability to form pairs at 19 degrees C and 37 degrees C were sought. Cells placed below 19 degrees C were unable to deciliate or fuse membrane in the holdfast region; at 37 degrees C, membrane fusion in both the holdfast and paroral regions was prevented. Time course studies on cross-fertilization reveal that temperatures 35 degrees C block all stages of the process up to the actual exchange of pronuclei. After the exchange has begun, the process continues despite the elevated temperature. Temperature shifts are discussed as a means of conditionally blocking critical points in the development program of conjugation.