The sorbitol dehydrogenase (SDH) gene of Bombyx mori begins to be expressed in diapause eggs after 5°C-chilling for 40-50 days. Because three elements similar to consensus sequences bound by members of the steroid hormone receptor superfamily such as Seven-up (SVP)/COUP-TF, were found in the 5′-upstream region of the SDH gene, we tried to isolate cDNAs for SVP from Bombyx eggs, as a step to understand the mechanism of how 5°C controls the SDH gene expression. Two cDNAs for SVP were cloned and named Bm svp-α and β, respectively. From the deduced amino-acid sequences, Bm svp-α protein was shown to have partial A/B region and C, D, E and F regions, whereas Bm svp-β protein lacked E (corresponding to the ligand-binding domain) and F regions. In non-diapause eggs, the temporal profile in the amount of Bm svp-α mRNA showed a peak in the middle of embryogenesis, while mRNA amounts of svp-β were much lower than those of svp-α. On the other hand, in diapause eggs, 5°C-chilling for 40-60 days enhanced levels of mRNA and protein for Bm svp-α, suggesting that Bm svp-α protein is a strong candidate of transcription factors that control the SDH gene expression induced by the cold.