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The Effects of Heat and Cold on Cellular Development in Synchronized Tetrahymena pyriformis WH‐6 *
Author(s) -
GAVIN RAY H.
Publication year - 1965
Publication title -
the journal of protozoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 0022-3921
DOI - 10.1111/j.1550-7408.1965.tb03218.x
Subject(s) - primordium , tetrahymena pyriformis , cell division , mitosis , tetrahymena , microbiology and biotechnology , biology , cell , genetics , gene
SYNOPSIS. Experiments were performed to ascertain the effect of heat and cold on oral and micronuclear development in synchronized Tetrahymena pyriformis WH‐6. The developing oral primordium becomes insensitive to cold sometime during stage 2. Cold shocks cause the reversion of many stage 2 primordia to stage 1. Cells so affected are set back in division. The delayed division is always asynchronous. When heat shocks are applied prior to late stage 4, the developing primordium will regress. High temperature shocks applied at later stages permit continued development. However, when the cell begins to cleave at the high temperature, division is frequently arrested and the new oral areas regress. Subsequent cell separation is greatly delayed and asynchronous. Heat and cold affect the micronucleus in the same way. Both agents prolong the arrest of mitosis brought about by the synchronizing treatment. A temperature shock is ineffective if applied after there is a space completely separating the chromosome groups, so that mitosis is completed in the presence of the agent. Bimicronucleate chains result in those cases in which division is arrested by heat shocks. It is suggested that the different phases of sensitivity to heat and cold may reflect different types of syntheses necessary for development of the oral primordium. Division arrest and subsequent oral replacement might possibly be related to high temperature induced changes in the physical state of the ciliate cortex.