HEAT-SHOCK INDUCED CHANGES OF PLANT-CELL ULTRASTRUCTURE AND AUTORADIOGRAPHIC LOCALIZATION OF HEAT-SHOCK PROTEINS

  • 1 January 1984
    • journal article
    • research article
    • Vol. 34  (2) , 254-264
Abstract
Treating tomato [Lycopersicon peruvianum] cell cultures and leaves by a physiological heat shock (hs) at 35-39.degree. C results in a progressive disintegration of the nucleolus and the assembly of cytoplasmic hs granules. Other ultrastructural changes are not observed. The alterations of the nucleoli coincide with an immediate stop of the processing and with a strongly decreased synthesis of pre-rRNA. Both hs effects are reversed after shift-down to normal temperature conditions (25.degree. C). Assembly of cytoplasmic hs granules depends on the accumulation of the newly forming hs proteins [hsp] and on supraoptimal temperatures. It is not observed in preinduced cultures synthesizing hs proteins at 25.degree. C. Autoradiographic studies reveal the preferential accumulation of hsp in the nucleoli and hs granules. Uridine labeling points to the presence of RNA in electron dense particles of both subcellular components. A survey on the state of hsp synthesis and structural binding as well as on the ultrastructural changes is given for 12 selected hs regimes.