published_or_final_version / abstract / Zoology / Master / Master of Philosophy

Cultured tobacco cells (Nicotiana tabacum L., cv Wisconsin-38) were subjected to temporary sub-lethal heat and salt shock treatments to determine the effects of these treatments on various physiological parameters after subsequent lethal heat or salt stresses. Tobacco cells developed a tolerance to a non-permissive temperature stress (54C for 14 min) when pretreated with heat shock of 38C for 2h but not when pretreated at 42C for 2h. Cells pretreated at 38 (2h) exhibited less than 30% normal growth when the 54C stress came immediately after the 38C treatment. Tolerance to the 54C stress developed with increased interval between shock and stress with cells exhibiting 95% normal regrowth when the 54C stress was administered 8h after the 38C shock. The developement of heat tolerance was inhibited if heat shock was done in the presence of a non-injuring level of EGTA (.0.5mM). Cells treated with EGTA during heat shock grew normally at 23C but not after a 54C heat stress. EDTA (0.5mM) had little effect on the acquisition of tolerance to heat stress.Wisconsin-38 cells developed a tolerance to a non-permissive salt stress (2% NaCl for 16h) when pretreated at a lower salt level (1.2% NaCl) for 3h. Cells heat shocked at 38C exhibited increased tolerance of the lethal salt stress up to 8h. Conversely, cells heat shocked at 42C exhibited immediate tolerance to lethal salt stress and this tolerance decayed over eight hours. The heat shock-induced acquisition of salt tolerance was inhibited by both EGTA and EDTA.Proteins synthesized during heat and salt stress treatments were labeled with [35S]-methionine and/or [3H]-leucine and separated using Sodium dodecylsulfate polyacrylamide gel electrophoresis. Fluorographic analysis of the gels indicate that a number of proteins are produced in response to heat shock. Similar analysis of proteins from salt shocked cells indicates that no salt shock proteins are produced in response to a brief low-level sodium chloride shock.

Thesis (Ph. D.)--University of Hawaii at Manoa, 1995. / Includes bibliographical references (leaves 118-133). / Microfiche. / xiii, 133 leaves, bound ill. 29 cm