Examination of heat shock protein mRNA accumulation in early Xenopus laevis embryos.
Elevation of the incubation temperature of Xenopus laevis neurulae from 22 to 33-35 degrees C induced the accumulation of heat shock protein (hsp) 70 mRNA (2.7 kilobases (kb)) and a putative hsp 87 mRNA (3.2 kb). While constitutive levels of both hsp mRNAs were detectable in unfertilized eggs and cleavage-stage embryos, heat-induced accumulation was not observed until after the mid-blastula stage. Exposure of Xenopus laevis embryos to other stressors, such as sodium arsenite or ethanol, also induced a developmental stage-dependent accumulation of hsp 70 mRNA. To characterize the effect of temperature on hsp 70 mRNA induction, neurulae were exposed to a range of temperatures (27-37 degrees C) for 1 h. Heat-induced hsp 70 mRNA accumulation was first detectable at 27 degrees C, with relatively greater levels at 30-35 degrees C and lower levels at 37 degrees C. A more complex effect of temperature on hsp 70 mRNA accumulation was observed in a series of time course experiments. While continuous exposure of neurulae to heat shock (27-35 degrees C) induced a transient accumulation of hsp 70 mRNA, the temporal pattern of hsp 70 mRNA accumulation was temperature dependent. Exposure of embryos to 33-35 degrees C induced maximum relative levels of hsp 70 mRNA within 1-1.5 h, while at 30 and 27 degrees C peak hsp 70 mRNA accumulation occurred at 3 and 12 h, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
D000818:Animals; D004274:DNA, Recombinant / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000502:physiology*; D006360:Heat-Shock Proteins / Q000235:genetics*; D007700:Kinetics; D009693:Nucleic Acid Hybridization; D012333:RNA, Messenger / Q000378:metabolism*; D014158:Transcription, Genetic; D014982:Xenopus laevis
D004274:DNA, Recombinant; D006360:Heat-Shock Proteins; D012333:RNA, Messenger