Characterization of a cDNA clone encoding a glycine‐rich cuticular protein of Tenebrio molitor: developmental expression and effect of a juvenile hormone analogue

Abstract

The complete sequence of a cDNA clone, isolated from epidermal mRNA of Tenebrio molitor using a monoclonal antibody raised against an adult-specific cuticular antigen only present in the hard cuticle, was obtained after primer extension at the 5' end. From this cDNA sequence, the deduced protein encompasses 199 amino acids (including a signal peptide) with a total molecular weight of 20.7 kDa. The protein exhibits a bipartite structure: glycine-rich region located in its NH2-terminal part and a carboxy-terminal domain sharing homologies with other cuticular proteins of Orthoptera, Diptera and Lepidoptera. In-situ hybridization analysis shows that the corresponding mRNA is present only in epidermal cells secreting the adult fibrous cuticle destined to become heavily sclerotized. In supernumerary pupae obtained after the application of the juvenile hormone analogue (JHA) to newly ecdysed pupae, the mRNA was undetectable, indicating that JHA can prevent the switch to the adult programme. However, in pupal-adult intermediates, obtained when JHA is applied later, the mRNA is detected.

A novel putative insect chitinase with multiple catalytic domains: hormonal regulation during metamorphosis

“…but a dramatic switch in gene expression is observed after the pupal-adult reprogramming, and these changes are prevented by application of the JH analogue [12]. We have used the differential display technique [13] to search for new JH target genes expressed in the epidermis of T. molitor.…”

Cloning and Sequencing of a cDNA Encoding a Larval‐Pupal‐Specific Cuticular Protein in Tenebrio Molitor (Insecta, Coleoptera)

“…Therefore, insect development is characterized by a periodic renewing of the cuticle (moulting process), including periodic shedding of the old cuticle (ecdysis). In holometabolous insects, the adult stage is reached after two metamorphic moults (pupal and adult moults) ; these dramatic changes require a considerable shift in gene expression, which is mainly controlled by two hormones, moulting hormone or 20-hydroxyecdysone and juvenile hormone.The structure and composition of cuticles, either larval, pupal or adult, may be very different, as demonstrated in several species by electrophoretic analyses (Srivastava, 1970; Roberts and Willis, 1980a,b;Chihara et al, 1982;Sridhara, 1983). In Tenehrio molitor (Insecta Coleoptera), previous studies (Roberts and Willis, 1980a,b; Lemoine and Delachambre, 1986; Lemoine et al, 1990) have shown that larval and pupal cuticle protein patterns are very similar, in contrast to the adult pattern.…”

“…The structure and composition of cuticles, either larval, pupal or adult, may be very different, as demonstrated in several species by electrophoretic analyses (Srivastava, 1970; Roberts and Willis, 1980a,b;Chihara et al, 1982;Sridhara, 1983). In Tenehrio molitor (Insecta Coleoptera), previous studies (Roberts and Willis, 1980a,b; Lemoine and Delachambre, 1986; Lemoine et al, 1990) have shown that larval and pupal cuticle protein patterns are very similar, in contrast to the adult pattern.…”

“…These differences suggest that the main changes in epidermal gene expression occur at the pupal-adult transition. Two preecdysial adult-specific cDNAs were previously isolated in this species ; TMACP-20 and TMACP-22, encoding proteins secreted during the deposition of preecdysial adult cuticle (Bouhin et al, 1992a;Charles et al, '1992). The corresponding mRNAs did not appear in supernumerary pupae obtained after juvenile hormone analoguc (methoprene) application, showing that adult-specific cuticular gene expression is inhibited by methoprene.…”

A Novel Chitin-binding Protein from the Vestimentiferan Riftia pachyptila Interacts Specifically with β-Chitin

“…RNA Isolation-Total RNA from tissues of the four main regions of the worm were extracted by the phenol/chloroform/isoamyl alcohol method as described previously (20). Poly(A)-rich RNA were purified by affinity with oligo(dT)-cellulose (21).…”