Catherine Lange

Individual geographical and experimental variation of cuticular hydrocarbons of the ant Cataglyphis cursor (Hymenoptera: Formicidae): their use in nest and subspecies recognition.

Abstract The cuticular hydrocarbons of Cataglyphis cursor (Fonsc.) adults have been identified and quantified. Comparison of the proportion of hydrocarbons in various locations shows a variation between populations from each side of the Rhǒne river and an isolated population in the mountains near Madrid. In the studied area (not including Italy and eastern places) at least three subspecies have been found. Ethological analyses show that colony recognition, as indicated by aggressive behavior and the possibilities of adoption in an allen society, is correlated with the composition of cuticular hydrocarbons. Callows can be adopted in an allen colony, they can live in two colonies where the adults do not tolerate each other. These adopted callows have a hydrocarbon pattern intermediate between the patterns of the another colony and the adoptive colony.

Interspecific recognition among termites of the genusReticulitermes: Evidence for a role for the cuticular hydrocarbons

Two species of termites,Reticulitermes (lucifugus) grassei andR. (l.) banyulensis, show a high degree of aggressivity toward each other. The epicuticular signature, recognized by contact, can be extracted using organic solvents, and the removal of the signature abolished all types of aggressive behavior. The signature can be transferred to lures, where it triggers interspecies aggression. It was found to be mainly present in the apolar fraction of the cuticular extracts, which contained only hydrocarbons, are determined by GC/MS techniques. Chemical recognition contributes towards isolation of the two species belonging to theR. lucifugus complex.

Cuticular hydrocarbons and defensive compounds of Reticulitermes flavipes (Kollar) and R. santonensis (Feytaud): polymorphism and chemotaxonomy

Colonies ofReticulitermes flavipes andR. santonensis were collected from the southeastern United States (Georgia) and the southwest of France (Charente-maritime). Defensive compounds and cuticular hydrocarbons were identified by gas chromatography-mass spectrometry and quantified by gas chromatography using an internal standard for each caste and all colonies. These analyses show that although the cuticular hydrocarbons ofR. santonensis in Europe andR. flavipes in Georgia are identical, their relative proportions are different. However, the defensive compounds synthesized by their soldiers are different. A strong chemical polymorphism between sympatric colonies ofR. flavipes in the SW United States was detected in terms of both the hydrocarbons of the workers and soldiers and in the defensive secretions of the soldiers. The six defensive secretion phenotypes are based on the presence or absence of terpenes whereas the cuticular hydrocarbon phenotypes are based on significant differences in the proportions of the various components. A multivariate analysis (analysis of principal components) clearly permitted discrimination of four phenotypes (three inR. flavipes and one inR. santonensis) without intermediates. The hydrocarbons responsible for these variations were identified, and it was shown that the variations are neither seasonal nor geographic. The phenotypes of the cuticular hydrocarbons (workers and soldiers) and defensive compounds are linked in each colony, forming in three groups inR. flavipes Georgia, one subdivided into four subgroups according to the defensive secretion phenotypes. The role of these polymorphisms is discussed and ethological tests indicate that the chemical polymorphism do not determine aggressive behavior. The taxonomic significance of these results is considered and two hypothesis are formulated: (1) We only detected a strong genetic polymorphism in one unique species, and we believe thatR. santonensis was introduced into Europe in the last century from oneR. flavipes colony. (2) Chemical variability characterizes the sibling species that can be grouped into the same subspeciesR. flavipes. Unknown mechanisms of reproductive isolation separate them.

In vivo and in vitro evidence for the biosynthesis of testosterone in the telencephalon of the female frog.

Abstract: Neurons and glial cells are capable of synthesizing various steroid hormones, but biosynthesis of testosterone in the CNS has never been reported. The aim of the present study was to demonstrate the synthesis of testosterone in the frog brain. The presence of 17β‐hydroxysteroid dehydrogenase (17β‐HSD)‐like immunoreactivity was detected in a population of glial cells located in the telencephalon. Reversed‐phase HPLC analysis of brain tissue extracts combined with radioimmunoassay detection revealed the presence of substantial amounts of testosterone and 5α‐dihydrotestosterone (5α‐DHT) in the telencephalon where 17β‐HSD‐positive cells were visualized. In male frogs, castration totally suppressed testosterone and 5α‐DHT in the blood and in the rhombencephalon but did not affect the concentration of these two steroids in the telencephalon. Chemical characterization of testosterone in female frog telencephalon extracts was performed by coupling HPLC analysis with gas chromatography‐mass spectrometry. Using the pulse‐chase technique with [3H]pregnenolone as a precursor, the formation of a series of metabolites was observed, including dehydroepiandrosterone, androstenedione, testosterone, 5α‐DHT, and estradiol. These data demonstrate the existence of an active form of 17β‐HSD in the frog telencephalon, which is likely involved in testosterone biosynthesis within the brain.

Induced mimicry of colony odors in ants

The cuticular hydrocarbons ofFormica selysi (Formicinae) andMonica rubida (Myrmicinae) reared in single species and in mixed species colonies were determined using gas chromatography (GC) and GC-mass spectrometry. In colonies containing both species, each species modified its species-specific recognition odor. This odor is composed, at least partly, of cuticular hydrocarbons. The cuticular hydrocarbons ofM. rubida consist only of saturated alkanes (n-alkanes and branched alkanes). InF. selysi the mixture also contains unsaturated compounds (monoenes and dienes). In hetero-specific colonies, a new chemical signature developed. This signature resulted from qualitative and quantitative changes in the spectrum of hydrocarbons produced by each species and permitted the two species to inhabit the same nest without displaying interspecific aggression. The readjustment seemed to be more an active synthesis or an active transfer than simply a passive transfer from one species to the other. This may imply that the ants synthesized some components of the hydrocarbon signature of the other species. These synthesizing processes may be activated under particular social environmental conditions.

Functional subcaste discrimination (foragers and brood-tenders) in the antCamponotus vagus scop.: polymorphism of cuticular hydrocarbon patterns.

In the antCamponotus vagus, when selected foragers that had been earlier removed from the foraging arena and brood-tenders that had been earlier removed from the nest were placed together in a foraging arena, most of the brood-tenders and only a few of the selected foragers were carried back to the nest by nonselected foragers. We hypothesize that cuticular hydrocarbons serve as a cue that allows foragers to discriminate between members of their own subcaste and brood-tenders. It has been established that the proportions of certain hydrocarbons, which are the same regardless of the colony studied, vary from one worker subcaste to another and thus constitute a specific chemical signature. These hydrocarbons belong to a wide range of chemical families (alkanes, monomethylalkanes, and dimethylalkanes). The greatest differences between the two subcastes were observed on the thorax of workers. Principal component analyses performed on the hydrocarbons (or hydrocarbon combinations) corresponding to the 45 main peaks in the cuticular profiles of the head and thorax of brood-tenders and foragers of several colonies show that there exist quantitative differences between the various signatures that characterize the colony, the worker subcastes, and the various body parts within the same species, which can be classified in a hierarchy where the differences between worker subcastes are less pronounced than those between body parts or between colonies.

Studies on the dynamics of the production of destruxins by Metarhizium anisopliae : direct high-performance liquid chromatographic and fast atom bombardment mass spectrometric analysis correlated with biological activity tests

Abstract In this work, the new strain Ma23 of the fungus Metarhizium anisopliae is demonstrated to be an effective source of destruxins, known insecticidal cyclodepsipeptides, under optimized culture conditions. The dynamics of the destruxin production is analysed by fast atom bombardment MS and HPLC, using wide-pore reversed-phase packings without any pretreatment of the culture media samples. By this approach, we show that twelve different destruxins are produced by M. anisopliae . The most abundant toxins have been unequivocally identified and HPLC quantitation shows that E destruxin, the most toxic compound of the series, accounts for ~35–40% of the whole toxin production from Ma23. A good correlation between the pathogenic effect of the fungal samples and amounts of destruxins produced is also demonstrated with an optimum of toxicity after four days.

Cuticular hydrocarbons of Calliphora vomitoria (Diptera): Relation to age and sex

Changes in epicuticular hydrocarbon content and composition were examined from 3 to 120 hr postemergence in both sexes of Calliphora vomitoria. n-Alkanes and mono- and dimethylalkanes with 20 to 31 carbon atoms were the major hydrocarbons detected. Alkenes were only detected in the females. Males had fewer hydrocarbons (40 versus 49 for the females). In males this number remained constant from 3 to 120 hr, whereas in females the number increased progressively from 3 to 48 hr. The males had a greater total of hydrocarbons than the females (x6 versus x3.5). They had significantly more hydrocarbons by 48 hr, the time of sexual maturation, while in females, the hydrocarbon content increased between 6 and 24 hr postemergence, just before the onset of previtellogenesis. Hydrocarbon synthesis continued up to 120 hr in males, but remained constant in the females after 24 hr. Hydrocarbon composition differed in males and females and between the young (3 and 6 hr) and the older animals (24 to 120 hr). The young animals were characterized by the presence of monomethylalkanes with chain lengths over 25C and the older animals by monomethylalkanes with chain lengths less than 25C. Alkenes were found only in females. The males were characterized by the presence of di- and monomethylalkanes with 23, 24, and 26 carbon atoms.

Orderly Pattern of Development of the Autoantibody Response in (New Zealand White × BXSB)F1 Lupus Mice: Characterization of Target Antigens and Antigen Spreading by Two-Dimensional Gel Electrophoresis and Mass Spectrometry

Immunoblots of a two-dimensional PAGE-separated HL-60 cell proteomic map and mass spectrometry were combined to characterize proteins targeted by autoantibodies produced by male (New Zealand White × BXSB)F1 (WB) mice that develop lupus and anti-phospholipid syndrome. Analysis of sera sequentially obtained from seven individual mice at different ages showed that six proteins, vimentin, heat shock protein 60, UV excision-repair protein RAD23, α-enolase, heterogeneous nuclear ribonucleoprotein L, and nucleophosmin, were the targets of the B cell autoimmune response, and that autoantibodies to them were synthesized sequentially in an orderly pattern that recurred in all the male WB mice analyzed: anti-vimentin first and anti-nucleophosmin last, with anti-RAD23 and anti-heat shock protein 60, then anti-α-enolase and anti-heterogeneous nuclear ribonucleoprotein L Abs occuring concomitantly. Anti-vimentin reactivity always appeared before anti-cardiolipin and anti-DNA Abs, suggesting that vimentin is the immunogen initiating the autoimmune process. The pattern of HL-60 proteins recognized by female WB sera differed from that of male sera, indicating that the Y chromosome-linked autoimmune acceleration gene is not an accelerator but a strong modifier of the autoimmune response. Thus, 1) combining two-dimensional PAGE and mass spectrometry constitutes a powerful tool to identify the set of Ags bound by autoantibodies present in a single serum and the whole autoantibody pattern of an autoimmune disease; 2) the diversification of the autoimmune response in male WB mice occurs in a predetermined pattern consistent with Ag spreading, and thus provides a useful model to further our understanding of the development of the autoantibody response in lupus.

Role of Cationization and Multimers Formation for Diastereomers Differentiation by Ion Mobility-Mass Spectrometry

AbstractStereochemistry plays an important role in biochemistry, particularly in therapeutic applications. Indeed, enantiomers have different biological activities, which can have important consequences. Many analytical techniques have been developed in order to allow the identification and the separation of stereoisomers. Here, we focused our work on the study of small diastereomers using the coupling of traveling wave ion mobility and mass spectrometry (TWIMS-MS) as a new alternative for stereochemistry study. In order to optimize the separation, the formation of adducts between diastereomers (M) and different alkali cations (X) was carried out. Thus, monomers [M + X]+ and multimers [2M + X]+ and [3M + X]+ ions have been studied from both experimental and theoretical viewpoints. Moreover, it has been shown that the study of the multimer [2Y + M + Li]+ ion, in which Y is an auxiliary diastereomeric ligand, allows the diastereomers separation. The combination of cationization, multimers ions formation, and IM-MS is a novel and powerful approach for the diastereomers identification. Thus, by this technique, diastereomers can be identified although they present very close conformations in gaseous phase. This work presents the first TWIMS-MS separation of diastereomers, which present very close collision cross section thanks to the formation of multimers and the use of an auxiliary diastereomeric ligand. Figureᅟ