Thirteen
hsp70 genes with complete conserved domains were identified in
Tetrahymena thermophila
, and expression of five similar and non-intron
hsp70 genes were analyzed. Under heat shock conditions of 37, 39 and 41°C,
hsp70-2 mRNA had the highest relative expression level, suggesting it is closely related to heat shock. The basal level of constitutive T.
thermophilahsp70-4 gene was high during 20 physiological/developmental stages of growth, starvation and conjugation, and it changed little upon exposure to heat shock: evidence that
hsp70-4 is an
hsc70 gene. The
hsp70-4 cDNA is 2 208 bp long, and contains an open reading frame of 1 959 bp encoding 635 amino acids. Microarray data indicated that
T. thermophilahsp70-3 gene probably participated in early starvation (0-12 h) stress and late conjugation (6-10 h) events, such as new macronuclear and micronuclear anlagen formation and old macronuclear elimination. However,
hsp70-5 gene possibly participates in late starvation (12-15 h) stress and early conjugation (0-6 h) events such as micronuclear meiosis, micronuclear exchange and pronuclear fusion. Blast2GO indicated that they participated in dissimilar biological processes, suggesting
hsp70-3 and
hsp70-5 perform different functions.
