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  • 1
    Electronic Resource
    Electronic Resource
    In Vivo and In Vitro Evidence for the Biosynthesis of Testosterone in the Telencephalon of the Female Frog (1996)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 67 (1996), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1996.67010413.x
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  • 2
    Electronic Resource
    Electronic Resource
    Interspecific recognition among termites of the genusReticulitermes: Evidence for a role for the cuticular hydrocarbons (1991)
    Springer
    Journal of chemical ecology 17 (1991), S. 2397-2420 
    Details
    ISSN: 1573-1561
    Keywords: Interspecific recognition ; Isoptera ; termites ; Reticulitermes ; cuticular hydrocarbons ; aggression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00994590
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  • 3
    Electronic Resource
    Electronic Resource
    Geranyllinalool (Diterpene Alcohol) (1990)
    Springer
    Journal of chemical ecology 16 (1990), S. 2067-2079 
    Details
    ISSN: 1573-1561
    Keywords: Geranyllinalool ; toxicity ; Isoptera ; Rhinotermitidae ; Reticulitermes ; soldier ; Pinus ; ants ; predators ; competitors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Geranyllinalool is an insecticidal component of pine wood and of the defensive secretion ofReticulitermes species. Lethal doses (LD50) were calculated for termites and various ant species. Termite workers were very resistant (10,000 ppm). Ant resistance varies among species according to their trophic strategy and attack mode. The geranyllinalool acts as a natural insecticide against some ant predators (LD50=6 ppm), which use raid or chemical crypsis to invade termite nests. In contrast, predators laying the venom on the cuticle of their termite prey were very resistant (10,000 ppm). Generally, ants acting as space competitors could detoxify the quantity emitted by one termite soldier (18 ppm).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01020517
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  • 4
    Electronic Resource
    Electronic Resource
    Functional subcaste discrimination (foragers and brood-tenders) in the antCamponotus vagus scop.: polymorphism of cuticular hydrocarbon patterns (1993)
    Springer
    Journal of chemical ecology 19 (1993), S. 1461-1477 
    Details
    ISSN: 1573-1561
    Keywords: Ants ; worker subcastes discrimination ; polyethism ; cuticular hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00984890
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  • 5
    Electronic Resource
    Electronic Resource
    Cuticular hydrocarbons and defensive compounds ofReticulitermes flavipes (Kollar) andR. santonensis (feytaud): Polymorphism and chemotaxonomy (1990)
    Springer
    Journal of chemical ecology 16 (1990), S. 3213-3244 
    Details
    ISSN: 1573-1561
    Keywords: Polymorphism ; chemotaxonomy ; Reticulitermes flavipes ; Reticulitermes santonensis ; Isoptera ; termites ; cuticular hydrocarbons ; defensive compounds ; terpenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00982094
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  • 6
    Electronic Resource
    Electronic Resource
    Induced mimicry of colony odors in ants (1991)
    Springer
    Journal of chemical ecology 17 (1991), S. 1641-1664 
    Details
    ISSN: 1573-1561
    Keywords: Formicinae ; mimicry ; artificial mixed colonies ; cuticular hydrocarbons ; colony recognition ; ants ; Hymenoptera ; Formicidae ; Formica selysi ; Monica rubida
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00984695
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  • 7
    Electronic Resource
    Electronic Resource
    Recent events (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 920-921 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290081112
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  • 8
    Electronic Resource
    Electronic Resource
    Desorption of ions from locust tissues. III. Study of a metabolite of A-destruxin using fast-atom bombardment linked-scan mass spectrometry (1995)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 9 (1995), S. 408-412 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The process of the detoxification of A-destruxin into a polar linear peptide in vivo in Locusta migratoria has been demonstrated using both high performance liquid chromatography and negative-ion fast-atom bombardment mass spectrometry. The final structure of the metabolite, after synthesis and comparison of retention time with the component in the crude biological mixture, was elucidated by positive-ion fast-atom bombardment linked-scan mass spectrometry. Diagnostic fragment ions produced by collision-induced dissociation are discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290090510
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  • 9
    Electronic Resource
    Electronic Resource
    Flash Vacuum Thermolysis - Synthesis and Characterization of Unstabilized Cycloalkenethiones (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 869-874 
    Details
    ISSN: 1434-193X
    Keywords: Thermochemistry ; Mass spectrometry ; Retro reactions ; Thioketones ; Cycloalkenethiones ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -The flash vacuum thermolysis (FVT) of cycloalkenyl allyl (or propargyl) sulfides 8, 9, 12, and 13 led, as the main thermal pathway, to the conjugated cycloalkenethiones 1, 3, and 5, resulting from a retro-ene reaction. These reactive thioketones, thus obtained in ca. 70% yield, have been characterized in the gas phase by mass spectrometry, and at low temperature by IR, UV/Vis and NMR spectroscopy. The polymerization of 1, 3, and 5 upon warming is generally more rapid than the other attempted reactions and only the [2 + 3] dipolar cycloaddition with diazomethane led in low yield, besides polymeric materials, to isomeric 1,3-dithiolanes 20 from cyclopentenethione 1. The obtention of the nonconjugated cycloalkenethiones 2 and 4, expected in the FVT of sulfides 10 and 11, has been confirmed only by UV/Vis spectroscopy at -196 °C, due to their rapid enethiolization. In the case of the large-ring sulfide 14, the (E) geometry of the double bond favoured the competitive retro-ene reaction yielding cyclododecene and propynethial; on the other hand, the FVT of the tricyclic gem-dithiol 15, a possible precursor of cyclobutenethione (7), led to vinyl thioketene (18), obtained by thermal ring opening of 7.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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