Cloning and expression of the nuclear transcription factor SlßFTZ-F1 cDNA from Spodoptera litura

Insect molting and metamorphosis are regulated by 20-hydroxyecdysone, which activates the ecdysone receptors, followed by expression of a series of transcription factors. Beta Fushi Tarazu-Factor 1 (beta FTZ-F1) is one of these ecdysis-related early-expressed transcription factors. A beta FTZ-F1 complementary DNA (cDNA) was cloned from Spodoptera litura. The full-length cDNA was 2 194 bp in length and the open reading frame of Sl beta FTZ-F1 cDNA consisted of 1 659 bp and encoded a 552-amino acid protein with a molecular mass of 61.4 kDa. Homology analysis revealed that Sl beta FTZ-F1 protein shared high identities to its homologues from other species. The A/B domains and the D domains were diverse among the insect beta FTZ-F1 proteins, but DNA binding domains (C domain) and the ligand binding domains (E domain) were highly conserved. Northern blot analysis detected a transcript of 2.2 kb in the epidermis of fifth to sixth molting larvae. Reverse transcription polymerase chain reaction revealed that Sl beta FTZ-F1 gene started to increasingly and periodically express before each molt, followed by a decrease during the intermolt stages.