Pheromone synthesis. Part 250: Determination of the stereostructure of CH503, a sex pheromone of male Drosophila melanogaster, as (3R,11Z,19Z)-3-acetoxy-11,19-octacosadien-1-ol by synthesis and chromatographic analysis of its eight isomers

Polar functional group-containing glycolipid CD1d ligands modulate cytokine-biasing responses and prevent experimental colitis

The MHC class I-like molecule CD1d is a nonpolymorphic antigen-presenting glycoprotein, and its ligands include glycolipids, such as α-GalCer. The complexes between CD1d and ligands activate natural killer T cells by T cell receptor recognition, leading to the secretion of various cytokines (IFN-γ, IL-4, IL-17A, etc.). Herein, we report structure-activity relationship studies of α-GalCer derivatives containing various functional groups in their lipid acyl chains. Several derivatives have been identified as potent CD1d ligands displaying higher cytokine induction levels and/or unique cytokine polarization. The studies also indicated that flexibility of the lipid moiety can affect the binding affinity, the total cytokine production level and/or cytokine biasing. Based on our immunological evaluation and investigation of physicochemical properties, we chose bisamide- and Bz amide-containing derivatives 2 and 3, and evaluated their in vivo efficacy in a DSS-induced model of ulcerative colitis. The derivative 3 that exhibits Th2- and Th17-biasing responses, demonstrated significant protective effects against intestinal inflammation in the DSS-induced model, after a single intraperitoneal injection.

The fatty acid elongase Bond is essential for Drosophila sex pheromone synthesis and male fertility

Insects use a spectacular variety of chemical signals to guide their social behaviours. How such chemical diversity arises is a long-standing problem in evolutionary biology. Here we describe the contribution of the fatty acid elongase Bond to both pheromone diversity and male fertility in Drosophila. Genetic manipulation and mass spectrometry analysis reveal that the loss of bond eliminates the male sex pheromone (3R,11Z,19Z)-3-acetoxy-11,19-octacosadien-1-ol (CH503). Unexpectedly, silencing bond expression severely suppresses male fertility and the fertility of conspecific rivals. These deficits are rescued on ectopic expression of bond in the male reproductive system. A comparative analysis across six Drosophila species shows that the gain of a novel transcription initiation site is correlated with bond expression in the ejaculatory bulb, a primary site of male pheromone production. Taken together, these results indicate that modification of cis-regulatory elements and subsequent changes in gene expression pattern is one mechanism by which pheromone diversity arises.

Insect behaviours are often guided by chemical signals, but little is known about how pheromone diversity evolves. Here the authors show that loss of the gene bond in Drosophila eliminates the sex pheromone CH503, while silencing it reduces the fertility of males and their conspecific rivals.

The neuropeptide tachykinin is essential for pheromone detection in a gustatory neural circuit

Gustatory pheromones play an essential role in shaping the behavior of many organisms. However, little is known about the processing of taste pheromones in higher order brain centers. Here, we describe a male-specific gustatory circuit in Drosophila that underlies the detection of the anti-aphrodisiac pheromone (3R,11Z,19Z)-3-acetoxy-11,19-octacosadien-1-ol (CH503). Using behavioral analysis, genetic manipulation, and live calcium imaging, we show that Gr68a-expressing neurons on the forelegs of male flies exhibit a sexually dimorphic physiological response to the pheromone and relay information to the central brain via peptidergic neurons. The release of tachykinin from 8 to 10 cells within the subesophageal zone is required for the pheromone-triggered courtship suppression. Taken together, this work describes a neuropeptide-modulated central brain circuit that underlies the programmed behavioral response to a gustatory sex pheromone. These results will allow further examination of the molecular basis by which innate behaviors are modulated by gustatory cues and physiological state.

5-Alkyl-1,2,3,4-tetrahydroquinolines, new membrane-interacting lipophilic metabolites produced by combined culture of Streptomyces nigrescens and Tsukamurella pulmonis

Eight novel 5-alkyl-1,2,3,4-tetrahydroquinolines (5aTHQs) bearing different side chains have been isolated from a combined culture of Streptomyces nigrescens HEK616 and Tsukamurella pulmonis TP-B0596. The chemical structures including the absolute configuration were elucidated by spectroscopic analysis and total synthesis. 5aTHQs inhibited the growth of wild-type fission yeast while only weakly inhibiting the growth of several mutant strains synthesizing premature ergosterol. These results demonstrate that 5aTHQs are novel antifungals that may target cell membranes.

Pheromone evolution and sexual behavior in Drosophila are shaped by male sensory exploitation of other males

Animals exhibit a spectacular array of traits to attract mates. Understanding the evolutionary origins of sexual features and preferences is a fundamental problem in evolutionary biology, and the mechanisms remain highly controversial. In some species, females choose mates based on direct benefits conferred by the male to the female and her offspring. Thus, female preferences are thought to originate and coevolve with male traits. In contrast, sensory exploitation occurs when expression of a male trait takes advantage of preexisting sensory biases in females. Here, we document in Drosophila a previously unidentified example of sensory exploitation of males by other males through the use of the sex pheromone CH503. We use mass spectrometry, high-performance liquid chromatography, and behavioral analysis to demonstrate that an antiaphrodisiac produced by males of the melanogaster subgroup also is effective in distant Drosophila relatives that do not express the pheromone. We further show that species that produce the pheromone have become less sensitive to the compound, illustrating that sensory adaptation occurs after sensory exploitation. Our findings provide a mechanism for the origin of a sex pheromone and show that sensory exploitation changes male sexual behavior over evolutionary time.

Stereochemical studies on pheromonal communications

Pheromonal communications are heavily dependent on the stereochemistry of pheromones. Their enantioselective syntheses could establish the absolute configuration of the naturally occurring pheromones, and clarified the unique relationships between absolute configuration and bioactivity. For example, neither the (R)- nor (S)-enantiomer of sulcatol, the aggregation pheromone of an ambrosia beetle, is behaviorally active, while their mixture is bioactive. Recent results as summarized in the present review further illustrate the unique and diverse relationships between stereochemistry and bioactivity of pheromones.

Synthesis and bioassay of the eight analogues of the CH503 male pheromone (3-acetoxy-11,19-octacosadien-1-ol) of the Drosophila melanogaster fruit fly

Eight analogues of (3R,11Z,19Z)-CH503 (3-acetoxy-11,19-octacosadien-1-ol), the anti-aphrodisiac pheromone of male Drosophila melanogaster, were synthesized for a bioassay. These were the enantiomers of 3-acetoxy-11,19-octacosadiyn-1-ol (1), 3-acetoxyoctacosan-1-ol (2), (Z)-3-acetoxy-11-octacosen-1-ol (3), and (Z)-3-acetoxy-19-octacosen-1-ol (4). None of them were pheromonally active, indicating that the two double bonds at C-11 and C-19 were necessary for bioactivity.

Synthesis of (1R,7Z)-1-methyl-7-hexadecenyl acetate, the female sex pheromone of the honey locust gall midge

(1R,7Z)-1-Methyl-7-hexadecenyl acetate (1), the female sex pheromone of the honey locust gall midge (Dasineura gleditchiae), was synthesized from 6-hepten-1-ol in an 8.9% overall yield (eight steps). Hydrolytic kinetic resolution of (±)-1,2-epoxy-8-heptadecyne was the key step in the synthesis.