Characterization of two new cuticular genes specifically expressed during the post-ecdysial molting period in Tenebrio molitor.

In a previous study, we have isolated a cDNA, TM-ACP17, coding for a post-ecdysial adult protein of Tenebrio molitor. After screening of a genomic library with TM-ACP17, we report isolation and sequencing of TM-ACP17 gene and a new gene, TM-LPCP29, coding for a larval-pupal protein. These two genes exhibit a common sequence of 15 nucleotides and a characteristic of most cuticular protein genes so far described: an intron interrupting the signal peptide. The deduced aa sequence of TM-LPCP29 exhibits a high percentage of Ala (26.5%) and Val (17.5%) and is highly hydrophobic. In the N-terminal part, the motif VAAPV is repeated ten times. Numerous histidine residues are present in the C- and N-terminal regions. A comparison is made with other cuticle protein sequences. Northern hybridization analysis showed that TM-LPCP29 is present during larval and mainly pupal post-ecdysial cuticle secretion. In-situ hybridization revealed that TM-LPCP29 mRNA is expressed in epidermis and not in muscles or fat body.