Rémy Brossut

A pheromone-binding protein from the cockroach Leucophaea maderae: cloning, expression and pheromone binding.

Odorant-binding proteins (OBPs) are thought to transport volatile compounds from air to their receptors through the sensillary lymph. In this protein family, the subgroup of pheromone-binding proteins (PBPs) is specifically tuned to the perception of the sexual pheromone. To date, the description of OBPs has been restricted to Endopterygota and Paraneoptera. Their expression in Orthopteroid has been hypothesized, but no evidence of OBP has been produced in this assemblage to date. In the present study, we describe the first OBP from a Dictyopteran insect that belongs to the cockroach Leucophaea maderae. The PBP of L. maderae (PBPLma) shares all the hallmarks of the OBP family and is expressed specifically in the female adult antennae, the sex that perceives the sexual pheromone. The affinity of the recombinant PBPLma produced in the Escherichia coli periplasm for the pheromonal compounds has been tested by displacement of a fluorophore, 8-anilino-1-naphtalenesulphonic acid (ANS). Our results suggest that two chemically close compounds of the pheromonal blend (3-hydroxy-butan-2-one and butane-2,3-diol) are capable of displacing ANS, whereas two other pheromone components (E-2-octenoic acid and senecioic acid) and other alkyl volatile compounds are not capable of displacing ANS, indicating a certain filtering of binding, which can be correlated with the putative function.

CHEMISTRY OF DEFENSIVE SECRETIONS IN NYMPHS AND ADULTS OF FIRE BUG, Pyrrhocoris apterus L. (HETEROPTERA, PYRRHOCORIDAE)

The defensive secretions from the nymphs and the adults of both sexes inP. apterus were chemically investigated. Forty components were identified from the nymphal posterior dorsoabdominal glands and 35 from the adult metathoracic glands of both sexes. Within the 43 identified chemicals, we found 23 aldehydes, five saturated hydrocarbons, five alcohols, three ketones, three lactones, two terpenes, one phenol and one ester. Thirteen of these compounds had never been reported within the Heteroptera. Whereas eight components are specific to the nymphs, methyl pentenal, (E)-2-hexenol, and heptadecanal are the only adult-specific components. The biological role of all the identified chemicals is almost unknown inP. apterus and is discussed comparatively with regard to other Heteroptera.

2-Methylthiazolidine and 4-ethylguaiacol, male sex pheromone components of the cockroachNauphoeta cinerea (dictyoptera, blaberidae): A reinvestigation

InNauphoeta cinerea, male calling behavior is associated with sex pheromone release by the sternal glands. The male pheromone that attracts females from a distance is a mixture of 2-methylthiazolidine and 4-ethylguaiacol. It is active at very low concentrations, 0.05 and 0.01 ng, respectively. Two other compounds, 3-hydroxy-2-butanone and 2-methyl-2thiazoline, act at close range, keeping the female in the vicinity of the male. The function of the volatile pheromone and those of previously described contact pheromones are discussed in regard to their possible involvement in the establishment of male dominant-subordinate relationships.

What does Cryptocercus kyebangensis, n.sp. (Dictyoptera: Blattaria: Polyphagidae) from Korea reveal about Cryptocercus evolution? A study in morphology, molecular phylogeny, and chemistry of tergal glands

Abstract The description of a new species of the woodroach Cryptocercus kyebangensis Grandcolas from South Korea offers the opportunity to bring comparative information within the genus. This species, though morphologically very similar to other East Asian and North American species, presents conspicuous differentiation of both ribosomal genes (sequenced fragments of 12S and 16S) and chemical blends from tergal glands (proportions of linalyl acetate and the alcohol 4, 6, 8-trimethyl-7, 9-undecadien-5-ol, compounds previously identified in females originating from North America). A phylogenetic reconstruction involving Blatta orientalis as an outgroup, Therea petiveriana as a polyphagid relative, C. kyebangensis and 17 North American Cryptocercus populations showed that C. kyebangensis stands as a sister-group of North American Cryptocercus, thus suggesting that one beringian vicariance has taken place in the early differentiation of the genus. Using sequence divergences within the framework of the molecular clock leads to comparable datation estimates for both ribosomal genes, ranging between Miocene and Pliocene for the whole history of the genus Cryptocercus, therefore congruent with previous phylogenetic biogeographical estimates. This new set of data for this East Asian species supports heterobathmy in the genus Cryptocercus and argues against the misleading “primitive taxon” concept. Species nova: Cryptocercus kyebangensis Grandcolas.

Molecular characterization of a male-specific glycosyl hydrolase, Lma-p72, secreted on to the abdominal surface of the Madeira cockroach Leucophaea maderae (Blaberidae, Oxyhaloinae)

The epicuticular surface protein Lma-p72 is specific to the abdominal secretions of Leucophaea maderae (Madeira cockroach) adult males. Natural Lma-p72 was purified and the complete cDNA sequence determined by reverse-transcription PCR using primers based on Edman degradation fragments. Northern blot and in situ hybridization analyses showed that Lma-p72 was expressed in the tergal and sternal glands. Sequence alignment indicates that Lma-p72 is closely related to the family 1 glycosyl hydrolases (EC 3.2.1). Native Lma-p72 was proved to be active in the abdominal secretions and exhibit a beta-galactosidase-like activity. However, weak specificity with respect to the C-4 configuration of the substrate was observed. Two main hypotheses were proposed concerning the function of this enzyme: Lma-p72 could hydrolyse oligosaccharides from the male abdominal secretions, making them more phagostimulatory for the female during the precopulatory behaviour. The protein could also cleave a pheromone-sugar conjugate to release the pheromonal compounds on to the cuticular surface. Such a sugar conjugate could be a transport form. Data from the first in vivo inhibition tests indicate that a glycosidase could be directly involved in the production process of some pheromonal compounds in L. maderae males.

Calling behaviour of female Periplaneta americana: Behavioural analysis and identification of the pheromone source

Abstract The site for the production of Periplanone B, one of the components of the female sex pheromone of Periplaneta americana , was localized in glands situated in the genital atrium, and we have called these structures atrial glands. While emitting the sex pheromone, females adopt a characteristic calling posture during which time the atrial glands are exposed. Behavioural assays of males utilizing pentane extracts of various female body parts revealed that atrial gland extracts are highly attractive, and induced more wing-raising behaviour, than any other female body part. GC-MS analyses support these results by revealing that Periplanone B is only present in the atrial glands. We estimate that about 30 ng of Periplanone B are present in the glands.

The Cryptocercus punctulatus species complex (Dictyoptera: Cryptocercidae) in the eastern United States: comparison of cuticular hydrocarbons, chromosome number, and DNA sequences.

The goal of the current study was to determine if cuticular hydrocarbons could be used to empirically delimit taxa within the Cryptocercus punctulatus species complex in the eastern United States. Cockroaches were collected from rotting logs in 22 locations across four states. Hydrocarbon phenotypes and two mitochondrial (16S and COII) genes and one nuclear (ITS2) gene were independently analyzed to determine their relationship with chromosome number. Five distinct hydrocarbon phenotypes were found, but these were only partly congruent with chromosome number and thus with purported species descriptions. Molecular and cuticular hydrocarbon data each indicate that Cryptocercus with a male karyotype of 2n=43 belong to at least two distinct, distantly related lineages. One 2n=43 lineage is sister group to the 2n=37 and 2n=39 clade, and has a unique hydrocarbon profile. The other 2n=43 lineage is sister group to the 2n=45 samples, and its cuticular hydrocarbons group with four samples of the 2n=45 lineage. The cuticular hydrocarbons of two additional 2n=45 samples diverge from this assemblage. Results indicate cuticular hydrocarbons and chromosome number have some degree of evolutionary independence; neither is completely reliable in delineating historical lineages. Our data provide support for the parallel model of chromosome evolution in the species complex.

Characterization of two male-specific polypeptides in the tergal glands secretions of the cockroach Leucophaea maderae (Dictyoptera, blaberidae)

During the sexual behavior of cockroaches, the female mounts the courting male to feed on the proteinaceous secretion of the tergal glands. Polyacrylamide gel electrophoresis of male and female protein extracts after cuticle wiping revealed three major bands. Two of 18 and 22 kDa, named Lma-P18 and Lma-P22, are specific to the male tergal extracts. Moreover, Lma-P22 is only found in the male second tergite extracts. The third one of 54 kDa, named Lma-P54, is common to male and female extracts and could be considered as an ubiquitous surface protein. Several other minor proteins are also present on the body surface of adults of both sexes. Quantitation of the total protein amount of the male tergal gland secretion shows a progressive accumulation from adult ecdysis to sexual maturity. Western blot analysis using antibodies raised against Lma-P22 and Lma-P54 confirms that Lma-P22 is only secreted by the male second tergite glands. Immunohistolocalization demonstrates that these three major proteins are produced by class 3 glandular cells.

Pheromones inBlattella germanica andBlaberus craniifer (Blaberoidea): Glandular source, morphology and analyses of pheromonally released behaviours

Females ofBlattella germanica andBlaberus craniifer produce a volatile sex pheromone attractive at a distance for conspecific males. During the emission of the pheromone, females ofB. craniifer adopt a typical calling posture; we never observe such a stance inB. germanica females. For both species, the glandular structures responsible for pheromonal production are located on the female pygidium. InB. germanica, the thickness of the glandular epithelium is clearly correlated with the attractiveness of females, being maximum for 13 day old females. The functions of the pygidial glands are discussed in both species.

Defensive secretions of nymphs and adults of five species of Pyrrhocoridae (Insecta: Heteroptera)

Abstract The chemical composition of the defensive secretions of the nymphs and the adults of Dysdercus fasciatus was investigated. Thirty compounds were identified from the nymphal posterior dorsoabdominal glands, and 34 from the adult metathoracic glands of both sexes. The data were compared with those reported for other species of Pyrrhocoridae. For the species Dysdercus cingulatus, D. fasciatus , and Pyrrhocoris apertus , 63 identified compounds can be divided into 11 chemical groups: aldehydes, saturated hydrocarbons, acetates, alcohols, terpenes, lactones, ketones, esters, alkenes, acids and miscellaneous compounds. These data and those from the literature on Dysdercus intermedius and Dysdercus supersitiosus were analysed by an Euclidian distance clustering which emphasized the differences between nymphal and adult secretions. D. fasciatus is the only species which displays a sexual dimorphism in the composition of the secretion of the metathoracic glands.