Studies on heat shock proteins in sea urchin development

Work on stress proteins in sea urchin embryos carried out over the last 20 years is reviewed and the following major results are described. Entire sea urchin embryos, if subjected to a rise in temperature at any postblastular stage undergo a wave of heal shock protein (hsp) synthesis and survive. If subjected to the same rise between fertilization and blaseula formation, t hey are not yet able to synthesize hsp and die. Four clones coding for the major hsp, hsp70, have been isolated and sequenced; evidence for the existe nce of a heat shock factor has been provided, and a mechanism for the devel opmental regulation of hsp synthesis discussed. Intraembryonic and intracel lular hsp location has been described; and a mechanism for achievement of t hermotolerance proposed. A chaperonine role for a constitutive mitochondria l hsp56 has been suggested, as well as a role for the constitutive hsp70 in cell division. Heat shock, if preceded by 12-O-tetradecanoyiphorbol-12-ace tate (TPA) treatment causes apoptosis.