Molecular cloning of the heat-shock cognate 70 (Hsc70) gene from the two-spotted spider mite, Tetranychus urticae, and its expression in response to heat shock and starvation

We isolated a heat shock cognate 70 (hsc70) gene from the two-spotted spider mite, Tetranychus urticae, a serious agricultural pest. The hsc70 cDNA is 2275 bp and contains a 1962 bp open reading frame. The translated amino acid sequence consists of 654 residues with a calculated molecular mass of 71,275 Da and an isoelectronic point (pI) of 5.52. It also contains the highly conserved functional motifs of the Hsp70 family. A comparison of the deduced amino acid sequence shows a high identity (81-84%) with Hsp70s/Hsc70s of insects but the highest identity is with mussel Hsc71 (86%). Northern blot hybridization indicates that the hsc70 transcript level of female adults is higher than that of male adults. We evaluated the response of hsc70 gene to stresses from temperature and starvation. The level of hsc70 mRNA was not significantly changed by heat and cold shocks nor by recovery after the shocks. However, the hsc70 mRNA level was decreased by food restriction of female mites. Analysis of nucleotide and deduced amino acid sequences of hsc70 gene from T. urticae suggests that it is a member of heat shock cognate 70 gene in the highly conserved Hsp70 family but that its expression is influenced by food restriction rather than thermal stress. This is the first molecular analysis of a heat shock protein gene in an acarid.