Shigeru Matsuyama

Mechanisms regulating caste differentiation in an aphid social system

For evolution and maintenance of the social systems of insect colonies, caste production should be controlled in response to external cues so that caste ratio in the colony is kept in an optimal range. Recent developments using artificial diet rearing techniques have revealed an underlying mechanism for adaptive control of caste production in a social aphid, Tuberaphis styraci, which has a sterile soldier caste in the 2nd instar. Aphid density was the proximate cue that acts on 1st instar nymphs and embryos to induce soldier differentiation. The final determination of soldier differentiation occurred postnatally, probably at a late 1st instar stage. Direct contact stimuli from live non-soldier aphids mediated the density effect. While coexisting non-soldiers facilitated soldier differentiation in 1st instar nymphs, coexisting soldiers acted to suppress such differentiation. These results suggest that caste production in aphid colonies is controlled by positive and negative feedback mechanisms consisting of density-dependent induction and suppression of soldier differentiation. Here, we demonstrate the mechanisms that coordinate aphid society, and provide a striking case of clonal superorganism system where simple responses of colony members to local extrinsic stimuli are integrated into a highly organized regulation of the whole colony.

Unusual periodicity of sex pheromone production in the large black chaferHolotrichia parallela

Abstract(R)-(−)-Linalool was identified as a minor component sex pheromone of the scarab beetleHolotrichia parallela (Coleoptera: Scarabaeidae). Field evaluations revealed that, although not attractive per se, (R)-(−)-linalool enhances the attractiveness of the major sex pheromone,L-isoleucine methyl ester (LIME). Analyses of the pheromone titers in the glands of field-collected females demonstrated the occurrence of peak levels of 48-hr (“circabidian”) periodicity. The levels of LIME in the glands of 45-day-old virgin females increased over three times from the scototo the photophase of a calling day, but the amounts of (R)-(−)-linalool did not significantly change. Virgin females had in average two times more LIME and 3.6 times more (R)-(−)-linalool than the average amount found in the field-captured beetles throughout the season.

An amino acid derivative as the sex pheromone of a scarab beetle

Since the identification of bombykol, a myriad of compounds have been reported as sex pheromones. Nevertheless, as highlighted by the examples of female Lepidoptera, which by and large utilize alcohols, acetates, aldehydes, and hydrocarbons, including epoxyhydrocarbons, pheromones are restricted to some groups of chemicals with marked structural similarities. Even in the Coleoptera, with more diversity in molecular structures, structurally related compounds are used by insects of the same family as evidenced by the scarab beetles; the sex pheromones of Popillia japonica, Anomala rufocuprea, and A. cuprea are (R,Z)-5-( )-(dec1 -enyl)oxacyclopentan-2-one [1], methyl (Z)-tetradec-5enoate [2] and (R,Z)-5-(-)-(oct-l-enyl) oxacyclopentan-2-one [3], respectively. On the other hand, Costelytra zealandica and Kheper lamarcki of the same family have been reported to utilize quite different chemicals, viz., phenol [4] and a mixture of hexadecanoic acid, 2,6-dimethyl-5-heptenoic acid, and (E)-nerolidol along with a polypeptide pheromone carrier [5], respectively. We report here that the large black chafer Holotrichia parallela (Mots.) (Coleoptera: Scarabaeidae), ookurokogane in Japanese, utilizes a unique sex pheromone, L-isoleucine methyl ester. H. parallela is an important agricultural pest in Japan, which was initially called Lachnosterna morosa Waterhouse [6] and later renamed [7].

Niemann–Pick type C2 protein mediating chemical communication in the worker ant

Significance Worker ants are responsible for various tasks for their colony. In their chemical communication, odorant-binding proteins and chemosensory proteins, which accumulate in the sensillum lymph in the antennae, play roles in transporting semiochemicals to chemosensory receptors. However, the number of these proteins is not sufficient to interact with a large number of semiochemicals. Niemann–Pick type C2 protein was identified from the antenna of the worker Japanese carpenter ant, Camponotus japonicus (CjapNPC2). CjapNPC2 accumulated in the sensillum cavity in the basiconic sensillum. The ligand-binding pocket was composed of a flexible β-structure, which allowed binding to various potential semiochemicals, some of which elicited antennal electrophysiological responses. CjapNPC2 might play crucial roles in chemical communication required to perform worker ant tasks. Ants are eusocial insects that are found in most regions of the world. Within its caste, worker ants are responsible for various tasks that are required for colony maintenance. In their chemical communication, α-helical carrier proteins, odorant-binding proteins, and chemosensory proteins, which accumulate in the sensillum lymph in the antennae, play essential roles in transferring hydrophobic semiochemicals to chemosensory receptors. It has been hypothesized that semiochemicals are recognized by α-helical carrier proteins. The number of these proteins, however, is not sufficient to interact with a large number of semiochemicals estimated from chemosensory receptor genes. Here we shed light on this conundrum by identifying a Niemann–Pick type C2 (NPC2) protein from the antenna of the worker Japanese carpenter ant, Camponotus japonicus (CjapNPC2). CjapNPC2 accumulated in the sensillum cavity in the basiconic sensillum. The ligand-binding pocket of CjapNPC2 was composed of a flexible β-structure that allowed it to bind to a wide range of potential semiochemicals. Some of the semiochemicals elicited electrophysiolgical responses in the worker antenna. In vertebrates, NPC2 acts as an essential carrier protein for cholesterol from late endosomes and lysosomes to other cellular organelles. However, the ants have evolved an NPC2 with a malleable ligand-binding pocket as a moderately selective carrier protein in the sensillum cavity of the basiconic sensillum. CjapNPC2 might be able to deliver various hydrophobic semiochemicals to chemosensory receptor neurons and plays crucial roles in chemical communication required to perform the worker ant tasks.

Unsaturated Cuticular Hydrocarbons Synergize Responses to Sex Attractant Pheromone in the Yellow Peach Moth, Conogethes punctiferalis

Four trienyl hydrocarbons, (Z3, Z6, Z9)-tricosatriene (Z3, Z6, Z9-23:HC), (Z3, Z6, Z9)-pentacosatriene (Z3, Z6, Z9-25:HC), (Z3, Z6, Z9)-heptacosatriene (Z3, Z6, Z9-27:HC), and (Z3, Z6, Z9)-nonacosatriene (Z3, Z6, Z9-29:HC) were identified in a non-polar fraction of the body wax of male and female yellow peach moth, Conogethes punctiferalis. The relative amounts and ratios of these hydrocarbons differed between sexes. In females, the ratios in body wax and pheromone gland extracts were similar, with lesser amounts found in gland extracts. Synergistic effects of these hydrocarbons when added to the known aldehyde pheromone components were assessed in wind tunnel tests. A blend of (E)-10-hexadecenal (E10-16: Ald) and (Z)-10-hexadecenal (Z10-16: Ald) elicited upwind flight and orientation of males to the pheromone source, but arriving males did not remain close to source for very long. Among the hydrocarbons identified, only Z3, Z6, Z9-23:HC enhanced the activity of the aldehyde blend by increasing the time spent close to the source and the number of source contacts. Z3, Z6, Z9-23:HC and (Z9)-heptacosene (Z9-27:HC) also increased close-range responses to the aldehyde blend. The activity of the aldehyde blend plus these two hydrocarbons was similar to that of crude pheromone extract. Positive dose-response relationships between the aldehyde blend and two hydrocarbon mixtures were found. The lowest doses that elicited synergism were 10−1 female equivalents (of body wax extracts) for the two hydrocarbons, and 10−2 female equivalents for the total unsaturated hydrocarbon mixture.

Analysis of Anal Secretions from Phlaeothripine Thrips

The anal secretions of 16 phlaeothripine thrips species (Thysanoptera: Phlaeothripidae) were studied, including a reinvestigation of three species previously reported. A total of 37 components were detected, including hydrocarbons, acetates, terpenes, carboxylic acids, a quinone, an aromatic compound, and a pyranone compound. The secretions of all species were composed of some of these components, with Xylaplothrips inquilinus possessing as many as 11 components. Of these components, (Z)-9-octadecene, (Z)-9-nonadecene, nonadecadiene, octanoic acid, decanoic acid, geranial, neral, α-pinene, β-pinene, caryophyllene, 2-hydroxy-6-methylbenzaldehyde, and two unidentified monoterpenes [UK-I (M+136) and UK-II (M+168)] were detected for the first time. The chemicals were species-specific; four Liothrips species and three Holothrips species could be distinguished from each other and their congeners by the GC profiles of the ether extracts of their anal secretions. The anal secretions of gall-inducing thrips commonly contained terpenes, of which citral (a mixture of geranial and neral) and β-acaridial repelled ants or had antifungal activity. The findings suggest that these terpenes play a defensive role and prevent galls from fungal infestation. 3-Butanoyl-4-hydroxy-6-methyl-2H-pyran-2-one, found from three Holothrips spp., caused paralysis in ants. Chemical analysis of anal secretion components is a useful method for the classification of tubuliferan species that are difficult to distinguish on the basis of morphological characters.

4,8-Dimethyldecanal, the Aggregation Pheromone of Tribolium castaneum, is Biosynthesized Through the Fatty Acid Pathway

Abstract4,8-Dimethyldecanal (4,8-DMD) is the aggregation pheromone produced by male red flour beetles (RFB), Tribolium castaneum. To elucidate the biosynthetic origin of 4,8-DMD, the following studies were performed: (1)effects of juvenile hormone (JH) III, and pathway inhibitors mevastatin, an inhibitor of the mevalonate pathway, and 2-octynoic acid, an inhibitor of the fatty acid pathway, were tested to determine whether 4,8-DMD is derived from the fatty acid pathway or the mevalonate pathway; (2) incorporation of 13C-labeled acetate, propionate, and mevalonolactone into 4,8-DMD was measured to directly determine the biosynthetic origin of 4,8-DMD; and (3) incorporation of deuterium-labeled precursors, including 2-methylbutanoate (C5D), 4-methylhexanoate (C7D), 2,6-dimethyloctanoate (C10D), and 4,8-dimethyldecanoate (C12D) was tested to determine whether 4,8-DMD is biosynthesized in the sequence AcPrAcPrAc (Ac; acetate, Pr; propionate). JH III was topically applied to males at various doses. Inhibitors and isotopically labeled substrates were administered orally by feeding the beetles flour treated with the substrates of interest, after which volatiles were collected from both sexes of RFBs. The amount of 4,8-DMD produced was significantly reduced with increasing doses of JH III. Also, 2-octynoic acid inhibited the production of 4,8-DMD, but mevastatin did not. Exposure of RFBs to [1-13C]acetate and [1-13C]propionate, but not [2-13C]mevalonolactone, resulted in incorporation of the labeled compounds into 4,8-DMD. RFBs fed flour treated with deuterium-labeled C5D, C10D, and C12D, but not C7D, incorporated these compounds into 4,8-DMD. The findings that the production of 4,8-DMD was inhibited by 2-octynoic acid but unaffected by mevastatin, combined with the high incorporation of [1-13C]acetate and [1-13C]propionate into 4,8-DMD and the incorporation of deuterated precursors, unambiguously demonstrated that 4,8-DMD is of fatty acid rather than terpene biosynthetic origin, and that the biosynthesis of 4,8-DMD proceeds in the sequence Ac-Pr-Ac-Pr-Ac.

Production of hydroxy-fatty acid derivatives from waste oil by Escherichia coli cells producing fungal cytochrome P450foxy.

Cytochrome P450foxy (P450foxy) is a fatty acid (FA) monooxygenase that is characterized by self-sufficient catalysis and high turnover numbers due to the fused structure of cytochrome P450 and its reductase. Here we found that resting recombinant Escherichia coli cells producing P450foxy converted saturated FA with a chain length of 7–16 carbon atoms to their ω − 1 to ω − 3 hydroxy derivatives. Most products were recovered from the culture supernatant. Decanoic acid was most efficiently converted to ω − 1 to ω − 3 hydroxy decanoic acids in the order of ω − 1 > ω − 2 > ω − 3, with a total product yield of 47%. We also found that P450foxy was more active against physiological fatty acyl esters such as monopalmitoyl glycerol, monopalmitoyl phospholipid, and palmitoyl CoA than free palmitic acid. The bacteria producing P450foxy were applicable as biocatalysts in the production of ω − 1 hydroxy palmitic acid from lard, vegetable, and soy sauce oil wastes from the food industry.

Anaerobic Coculture of Microalgae with Thermosipho globiformans and Methanocaldococcus jannaschii at 68°C Enhances Generation of n-Alkane-Rich Biofuels after Pyrolysis

ABSTRACT We tested different alga-bacterium-archaeon consortia to investigate the production of oil-like mixtures, expecting that n-alkane-rich biofuels might be synthesized after pyrolysis. Thermosipho globiformans and Methanocaldococcus jannaschii were cocultured at 68°C with microalgae for 9 days under two anaerobic conditions, followed by pyrolysis at 300°C for 4 days. Arthrospira platensis (Cyanobacteria), Dunaliella tertiolecta (Chlorophyta), Emiliania huxleyi (Haptophyta), and Euglena gracilis (Euglenophyta) served as microalgal raw materials. D. tertiolecta, E. huxleyi, and E. gracilis cocultured with the bacterium and archaeon inhibited their growth and CH4 production. E. huxleyi had the strongest inhibitory effect. Biofuel generation was enhanced by reducing impurities containing alkanenitriles during pyrolysis. The composition and amounts of n-alkanes produced by pyrolysis were closely related to the lipid contents and composition of the microalgae. Pyrolysis of A. platensis and D. tertiolecta containing mainly phospholipids and glycolipids generated short-carbon-chain n-alkanes (n-tridecane to n-nonadecane) and considerable amounts of isoprenoids. E. gracilis also produced mainly short n-alkanes. In contrast, E. huxleyi containing long-chain (31 and 33 carbon atoms) alkenes and very long-chain (37 to 39 carbon atoms) alkenones, in addition to phospholipids and glycolipids, generated a high yield of n-alkanes of various lengths (n-tridecane to n-pentatriacontane). The gas chromatography-mass spectrometry (GC-MS) profiles of these n-alkanes were similar to those of native petroleum crude oils despite containing a considerable amount of n-hentriacontane. The ratio of phytane to n-octadecane was also similar to that of native crude oils.

Phytotoxic action mechanism of hapalocyclamide in lettuce seedlings.

Hapalocyclamide (cyclo-thiazole-L-alanine-oxazole-D-alanine-D-thiazoline-d-phenylalanine), a hexapeptide phytotoxic compound, was isolated from the terrestrial cyanobacterium Hapalosiphon sp. The phytotoxic action of the compound was investigated in lettuce (Lactuca sativa L. cv. Great Lakes no. 366) by determining its effects on several physiological processes. Hapalocyclamide effectively inhibited mitosis process in root tips, which resulted in the suppression of primary root growth of lettuce. The compound also induced overproduction of reactive oxygen species (ROS) and loss of cell viability in root cells. Moreover, hapalocyclamide-induced lipid peroxidation in both roots and shoots. Therefore, the primary action of hapalocyclamide to suppress lettuce growth might be caused by ROS overproduction, which induces major oxidative damage to membrane lipids, resulting in cell death and growth inhibition.