Identification, sequence and mRNA expression pattern during metamorphosis of a cDNA encoding a glycine-rich cuticular protein in Tenebrio molitor

The study of insect cuticular proteins and their sequences is of interest because they are involved in protein-protein and protein-chitin interactions which confer the mechanical properties and fine architecture of the cuticle. Moreover, in the coleopteran Tenebrio molitor there is a dramatic change in cuticular architecture between pre- and postecdysial secretion. We report the isolation, by differential screening, and the sequence characterization of a cDNA clone encoding a cuticular protein of T. molitor, ACP17. After insertion in the expression vector pEX1, the recognition of the fusion protein by an anti-cuticular monoclonal antibody confirmed the cuticular nature of ACP17. Northern hy…

The fine structure of colleterial glands in two cockroaches and three termites, including a detailed study of Cryptocercus punctulatus (Blattaria, Cryptocercidae) and Mastotermes darwiniensis (Isoptera, Mastotermitidae)

1873-5495 (Electronic) Journal Article Research Support, U.S. Gov't, Non-P.H.S.; The colleterial glands of insects are organs associated with the female genital apparatus. In cockroaches, these glands produce secretions that cover two parallel rows of eggs during oviposition, and in oviparous species, these secretions become the tanned, sculpted, rigid outer casing of the ootheca. The goal of this study was to compare the gross anatomy of the colleterial glands and the ultrastructure of their component tubules in the phylogenetically significant genera Cryptocercus (Blattaria) and Mastotermes (Isoptera). Recent studies indicate that cockroaches in the genus Cryptocercus are the sister group…

cDNA cloning and deduced amino acid sequence of a major, glycine-rich cuticular protein from the coleopteran Tenebrio molitor. Temporal and spatial distribution of the transcript during metamorphosis

0014-2956 (Print) Journal Article Research Support, Non-U.S. Gov't; In Coleoptera, the elytra (forewings), with a very hard and thick cuticle, protect the membranous and delicate hindwings against mechanical stress. We have isolated and characterized a cDNA encoding a major cuticle protein in Tenebrio molitor, named ACP-20. The deduced amino acid sequence is roughly tripartite, with two terminal glycine-rich domains and a central region showing pronounced similarities with some other hard cuticle proteins. Northern blot and in situ hybridization analyses reveal that ACP-20 gene expression is developmentally regulated since transcript accumulation occurs only in epidermal regions synthesizin…

Ultrastructure of posterior sternal glands of Macrotermes annandalei (Silvestri): new members of the sexual glandular set found in termites (Insecta).

In female alates of Macrotermes annandalei, two types of abdominal glands are involved in the secretion of sex pheromone. Tergal glands are found at the anterior margin of tergites 6-10 and posterior sternal glands (PSGs) are located at the anterior margin of sternites 6-7. The cytological features of both types of glands are quite similar. The fine structural organization of PSGs is studied more precisely and described for the first time. The glandular cuticle is pitted with narrow apertures corresponding to the openings of numerous subcuticular pouches. Several Class 3 glandular units open in each pouch. One canal cell and one secretory cell make an individual glandular unit. The canal ce…

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

0962-1075 (Print) Journal Article; 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 corre…

Cloning and Sequencing of a cDNA Encoding a Larval-Pupal-Specific Cuticular Protein in Tenebrio Molitor (Insecta, Coleoptera). Developmental Expression and Effect of a Juvenile Hormone Analogue

A cDNA clone encoding a larval-pupal cuticular protein, named TMLPCP-22, has been isolated by screening a library in expression vector with a monoclonal antibody made against pupal cuticular proteins of Tenebrio molitor. Northern-blot and in situ hybridization analyses showed that the expression of TMLPCP-22 is regulated in a stage-specific and tissue-specific manner; the transcript was present during the secretion of preecdysial larval and pupal cuticles and was restricted to epidermal cells. No expression was observed during adult cuticle deposition. In supernumerary pupae obtained after application of a juvenile hormone analogue, which is known to inhibit the adult programme, TMLPCP-22 m…

Characterization of Urbain, a gene expressed during Bombyx mori imaginal wing discs morphogenesis

Isolation and characterization of Urbain, a 20-hydroxyecdysone-inducible gene expressed during morphogenesis of Bombyx mori wing imaginal discs.

In insects, wing imaginal discs respond to the steroid hormone 20-hydroxyecdysone by initiating morphogenesis leading to the formation of the adult flight appendages. In this work we analyse the expression of a Bombyx gene, referred to as Urbain, whose cDNA had been previously isolated from wing discs (Chareyre et al. 1993). Accumulation of the 1.8 kb transcript occurs concomitantly with the increase of 20-hydroxyecdysone titer at every stage examined during post-embryonic development. In vitro, its accumulation is delayed 6–9 h after exposure to 20-hydroxyecdysone. Studies in the presence of cycloheximide have established that Urbain is a secondary response gene. The sequence of the mRNA c…

Sex pheromone identified after solid phase microextraction from tergal glands of female alates in Cornitermes bequaerti (Isoptera, Nasutitermitinae)

For the first time, a termite sex pheromone secreted by tergal glands has been isolated and identified. In the mandibulate nasute termite Cornitermes bequaerti, pairing of swarming imagoes is mediated by a sex pheromone secreted by females from their tergal glands. These well developed sexual glands located in front of tergites 8, 9, 10 are essentially composed of class 1 and 2 cells, but also of some glandular units of class 3 cells. The major volatile compound of tergal secretion was isolated by solid phase microextraction (SPME) and identified by GC-MS as (3Z, 6Z, 8E)-dodecatrien-1-ol. Sex attraction bioassays with synthetic (3Z, 6Z, 8E)-dodecatrien-1-ol showed that this alcohol was the …