Chemotaxonomy of the Hymenophyllaceae. II. C-GLYCOSYLFLAVONES AND FLAVONE-O-GLYCOSIDES OF TRICHOMANES S.L.

An analysis of 23 species of Trichomanes s. 1. indicates that the presence of C-glycosylflavones, especially mono-C-glycosylflavones, may be a basic characteristic for this genus. Except for the morphologically unique Cardiomanes reniforme, this feature appears to delimit the species of Trichomanes s. 1. from those of Hymenophyllum s. 1. Several species, primarily those classified within Didymoglossum (according to both Copeland and Morton), synthesize flavone-O-glycosides in addition to their C-glycosylflavone profiles. Two species, T. birmanicum and T. radicans, appear to be unique in synthesizing the di-C-glycosylflavones violanthin and isoviolanthin; five species (T. collariatum, T. scandins, T. birmanicum, T. bicorne, and T. alatum) appear to synthesize di-C-glycosylflavones but lack mono-C-glycosylflavones. Based on this and other studies, it may be appropriate to consider these C-glycosylflavone-producing plants as representing primitive leptosporangiate stock.     

Coordination chemistry of molybdenum relevant to hydrodenitrogenation: Reactivity of Mo(PMe3)6 towards 6-membered heterocyclic aromatic nitrogen compounds involving C-H bond cleavage and η-coordination

The reactivity of Mo(PMe₃)₆ towards 6-membered heterocyclic aromatic nitrogen compounds, namely pyridine, pyrazine, pyrimidine and triazine, has been investigated as part of an effort to define the coordination chemistry of molybdenum relevant to hydrodenitrogenation. For example, Mo(PMe₃)₆ reacts with pyridine to yield initially (η²-N,C-pyridyl)Mo(PMe₃)₄H, an uncommon example of an η²-pyridyl-hydride complex. The formation of (η²-N,C-pyridyl)Mo(PMe₃)₄H is reversible and treatment with PMe₃ regenerates Mo(PMe₃)₆ and pyridine. At elevated temperatures, (η²-N,C-pyridyl)Mo(PMe₃)₄H dissociates PMe₃ and converts to the η⁶-pyridine complex (η⁶-pyridine)Mo(PMe₃)₃. Pyrazine, pyrimidine and 1,3,5-triazine likewise react with Mo(PMe₃)₆ to yield (η²-N,C-pyrazinyl)Mo(PMe₃)₄H, (η²-N,C-pyrimidinyl)Mo(PMe₃)₄H and (η²-N,C-triazinyl)Mo(PMe₃)₄H, respectively. At elevated temperatures (η²-N,C-pyrazinyl)Mo(PMe₃)₄H and (η²-N,C-pyrimidinyl)Mo(PMe₃)₄H dissociate PMe₃ and convert to (η⁶-pyrazine)Mo(PMe₃)₃ and (η⁶-pyrimidine)Mo(PMe₃)₃ in which the heterocycle coordinates to molybdenum in an unprecedented η⁶-manner.     

Characterization of eubacterial and archaeal community diversity in the pit mud of Chinese Luzhou-flavor liquor by nested PCR–DGGE

The aim of this study was to investigate and compare the microbial community structures of eubacteria and archaea in the pit mud of Chinese Luzhou-flavor liquor from the wall (C_w) and bottom (C_b) of cellar through nested PCR–denaturing gradient gel electrophoresis (DGGE). The Shannon–Wiener index (H) calculated from the DGGE profiles showed that the community diversities of eubacteria and archaea in samples from C_b were almost higher than that from C_w. In addition, cluster analysis of the DGGE profiles revealed that some differences were found in the microbial community structure in samples from different locations. The closely relative microorganisms of all eubacterial 16S rRNA gene sequences fell into four phyla (Firmicutes, Proteobacteria, Bacteroidetes and Actinobacteria), including 12 genera and 2 uncultured eubacteria. Moreover, 37.1 % eubacteria were affiliated with Clostridium. Particularly, genus Acinetobacter was absent in all samples from C_b but present in all samples from C_w. The closely relative microorganisms of all archaeal 16S rRNA gene sequences fell into four genera, which included Methanobrevibacter, Methanoculleus, Methanobacterium and Methanosaeta, while the dominant archaea in samples from C_w and C_b were similar. Results presented in this study provide further understanding of the spatial differences in microbial community structure in the pit mud, and is of great importance for the production and quality improvement of Luzhou-flavor liquor.     

Structure and Biosynthesis of Cuticular Lipids: Hydroxylation of Palmitic Acid and Decarboxylation of C(28), C(30), and C(32) Acids in Vicia faba Flowers

The structure and composition of the cutin monomers from the flower petals of Vicia faba were determined by hydrogenolysis (LiAlH₄) or deuterolysis (LiAlD₄) followed by thin layer chromatography and combined gas-liquid chromatography and mass spectrometry. The major components were 10, 16-dihydroxyhexadecanoic acid (79.8%), 9, 16-dihydroxyhexadecanoic acid (4.2%), 16-hydroxyhexadecanoic acid (4.2%), 18-hydroxyoctadecanoic acid (1.6%), and hexadecanoic acid (2.4%). These results show that flower petal cutin is very similar to leaf cutin of V. faba. Developing petals readily incorporated exogenous [1-¹⁴C]palmitic acid into cutin. Direct conversion of the exogeneous acid into 16-hydroxyhexadecanoic acid, 10, 16-dihydroxy-, and 9, 16-dihydroxyhexadecanoic acid was demonstrated by radio gas-liquid chromatography of their chemical degradation products. About 1% of the exogenous [1-¹⁴C]palmitic acid was incorporated into C₂₇, C₂₉, and C₃₁n-alkanes, which were identified by combined gas-liquid chromatography and mass spectrometry as the major components of the hydrocarbons of V. faba flowers. The radioactivity distribution among these three alkanes (C₂₇, 15%; C₂₉, 48%; C₃₁, 38%) was similar to the per cent composition of the alkanes (C₂₇, 12%; C₂₉, 43%; C₃₁, 44%). [1-¹⁴C]Stearic acid was also incorporated into C₂₇, C₂₉, and C₃₁n-alkanes in good yield (3%). Trichloroacetate, which has been postulated to be an inhibitor of fatty acid elongation, inhibited the conversion of [1-¹⁴C]stearic acid to alkanes, and the inhibition was greatest for the longer alkanes. Developing flower petals also incorporated exogenous C₂₈, C₃₀, and C₃₂ acids into alkanes in 0.5% to 5% yields. [G-³H]n-octacosanoic acid (C₂₈) was incorporated into C₂₇, C₂₉, and C₃₁n-alkanes. [G-³H]n-triacontanoic acid (C₃₀) was incorporated mainly into C₂₉ and C₃₁ alkanes, whereas [9, 10, 11-³H]n-dotriacontanoic acid (C₃₂) was converted mainly to C₃₁ alkane. Trichloroacetate inhibited the conversion of the exogenous acids into alkanes with carbon chains longer than the exogenous acid, and at the same time increased the amount of the direct decarboxylation product formed. These results clearly demonstrate direct decarboxylation as well as elongation and decarboxylation of exogenous fatty acids, and thus constitute the most direct evidence thus far obtained for an elongation-decarboxylation mechanism for the biosynthesis of alkanes.     

Pollen morphology of some endemic Turkish Centaurea L. (Asteraceae, section Phaloletis) and their taxonomic value

In this study, the detailed pollen morphological structures of some endemic Turkish species of Centaurea amaena Boiss., C. antalyense H. Duman & A. Duran, C. aphrodisea Boiss., C. hierapolitana Boiss., C. luschaniana Heimerl, C. lycia Boiss., C. tossiensis Freyn. Et Sint., and C. wagenitzii Hub.-Mor. (Asteraceae, section Phaloletis) were studied under light microscopy (LM) and scanning electron microscopy (SEM) for the first time. LM and SEM investigations showed that the pollen grains of eight taxa are more or less spheroidal-subprolate, the amb triangular and tricolporate. The exine sculpture is tectate, microechinate-scabrate in the pollen of Centaurea taxa. Spinules are less dense in Centaurea amaena, C. antalyense, C. hierapolitana, and C. lycia, but they are more dense in C. aphrodisea, C. luschaniana, C. tossiensis, and C. wagenitzii. Spinule dimensions are different from each other. The exine has one layer of columellae beneath the spines. We determined all taxa that have the Helianthoid type. Exine sctructure and sculpture as well as spine density and dimensions in Asteraceae are the most reliable characteristics for discriminating taxa.     

Host--virus interactions in the control of T4 prereplicative transcription. I. tabC (rho) mutants.

In this paper we describe properties of old (Takahashi, 1978) and new tabC^ts and tabC^cs bacterial mutants. We find that under non-permissive conditions they differently inhibit the synthesis of specific T4 prereplicative gene products. Among such products, that we have been able to identify, are P43 and PrIIA. In contrast, P32 and PrIIB are not affected.Inhibition of P43 (T4 DNA polymerase) synthesis is sufficient to account for depressed DNA synthesis in tabC (Takahashi, 1978).In heterodiploids: (1) all tabC mutants are recessive; (2) all tabC mutants do not complement with each other; (3) at least one, tabC^ts-5521, becomes dominant at 42.6 °C if rho mutant ts15 (Tab⁺) (Das et al., 1976) is situated in trans; (4) tabC^ts-5521 also becomes dominant at 42.6 °C if tabC^cs-110 and tabC^cs-18 are situated in trans (42.6 °C is non-permissive for T4 development on tabC^cs-5521 and permissive for T4 development on tabC^cs mutants).We discuss the possibility that in tabC mutants rho protein is altered and insensitive to T4-specific anti-termination functions. We also discuss a model that accounts for the differential effect of tabC mutants on the synthesis of T4 prereplicative proteins.     

Flavodoxin-Like Proteins Protect Candida albicans from Oxidative Stress and Promote Virulence

The fungal pathogen Candida albicans causes lethal systemic infections in humans. To better define how pathogens resist oxidative attack by the immune system, we examined a family of four Flavodoxin-Like Proteins (FLPs) in C. albicans. In agreement with previous studies showing that FLPs in bacteria and plants act as NAD(P)H quinone oxidoreductases, a C. albicans quadruple mutant lacking all four FLPs (pst1Δ, pst2Δ, pst3Δ, ycp4Δ) was more sensitive to benzoquinone. Interestingly, the quadruple mutant was also more sensitive to a variety of oxidants. Quinone reductase activity confers important antioxidant effects because resistance to oxidation was restored in the quadruple mutant by expressing either Escherichia coli wrbA or mammalian NQO1, two distinct types of quinone reductases. FLPs were detected at the plasma membrane in C. albicans, and the quadruple mutant was more sensitive to linolenic acid, a polyunsaturated fatty acid that can auto-oxidize and promote lipid peroxidation. These observations suggested that FLPs reduce ubiquinone (coenzyme Q), enabling it to serve as an antioxidant in the membrane. In support of this, a C. albicans coq3Δ mutant that fails to synthesize ubiquinone was also highly sensitive to oxidative stress. FLPs are critical for survival in the host, as the quadruple mutant was avirulent in a mouse model of systemic candidiasis under conditions where infection with wild type C. albicans was lethal. The quadruple mutant cells initially grew well in kidneys, the major site of C. albicans growth in mice, but then declined after the influx of neutrophils and by day 4 post-infection 33% of the mice cleared the infection. Thus, FLPs and ubiquinone are important new antioxidant mechanisms that are critical for fungal virulence. The potential of FLPs as novel targets for antifungal therapy is further underscored by their absence in mammalian cells.     

Responses of the carbon and oxygen isotope compositions of desert plants to spatial variation in soil salinity in Central Asia

We examined the isotopic parameters in two C₃ species (Artemisia diffusa H. Krasch and Tamarix hispida Willd.) and a C₄ species [Haloxylon aphyllum (Minkw.) Iljin.] growing or planted in soils with different levels of salinity in a Central Asian desert. The oxygen isotope ratios of stem water (δ¹⁸O_stem) in T. hispida and H. aphyllum distributed in high-salinity zones were similar to the δ¹⁸O of artesian water (δ¹⁸O_artesian) and different from that in A. diffusa distributed in lower-salinity zones. This indicates that T. hispida and H. aphyllum depend on water with low salinity in the deeper soil layer, whereas A. diffusa depends on water in the shallower soil layer that would be affected by salt accumulation. The carbon isotope composition of leaf organic matter (δ¹³C_om) and oxygen isotope enrichment in leaf organic matter above stem water (Δ¹⁸O_om) were lower in A. diffusa than in the other species. The responses of δ¹³C_om and Δ¹⁸O_om to soil salinity observed for T. hispida suggest that the species decreased its transpiration rate and increased its intrinsic water-use efficiency in response to increasing soil salinity. The δ¹³C_om and Δ¹⁸O_om of H. aphyllum were higher than those of the C₃ species, and were not correlated with soil salinity, suggesting that H. aphyllum reduced its salt uptake by decreasing transpiration—even though it was able to access less saline water in the deeper soil layer. These results indicate that the water-use strategy of desert plants in high-salinity environments can be assessed based on their carbon and oxygen isotope ratios.     

Human leukocyte antigen (HLA)-C polymorphisms are associated with a decreased risk of rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune rheumatological disease thought to have substantial genetic contributions. Several genetic factors involved in the susceptibility to psoriasis and psoriatic arthritis (PsA) have been identified with genome-wide association studies, including human leukocyte antigen (HLA)-C, junction adhesion molecule 2 (JAM2) and REL. Psoriasis and PsA may share many features in common with RA. We hypothesized that this polymorphism may contribute to RA susceptibility in a Chinese population. We studied HLA-C rs10484554 C/T, HLA-C rs12212594 T/C, HLA-C rs12191877 C/T, JAM2 rs2829866 A/T and REL rs702873 G/A polymorphisms in 520 patients with RA and 520 controls in a Chinese population. HLA-C rs12191877 C/T polymorphism was in complete linkage disequilibrium (LD) (D′ = 1.0, r ² = 1.0) with HLA-C rs10484554 C/T polymorphism. When the HLA-C rs10484554 CC homozygote genotype was used as the reference group, the TT/CT genotypes were associated with a significantly decreased risk for RA (adjusted OR = 0.72, 95 % CI = 0.52–0.99, p = 0.044). We found that the HLA-C rs12191877 C/T polymorphism was also associated with a decreased risk of RA. HLA-C rs12212594 T/C, JAM2 rs2829866 A/T and REL rs702873 G/A polymorphisms were not associated with the risk of RA. These results provide evidence that HLA-C polymorphisms are associated with a decreased risk of RA.     

In planta cleavage of carotenoids by <Emphasis Type="Italic">Arabidopsis</Emphasis> carotenoid cleavage dioxygenase 4 in transgenic rice plants

A family of carotenoid cleavage dioxygenases (CCDs) produces diverse apocarotenoid compounds via the oxidative cleavage of carotenoids as substrates. Their types are highly dependent on the action of the CCD family to cleave the double bonds at the specific position on the carotenoids. Here, we report in vivo function of the AtCCD4 gene, one of the nine members of the Arabidopsis CCD gene family, in transgenic rice plants. Using two independent single-copy rice lines overexpressing the AtCCD4 transgene, the targeted analysis for carotenoids and apocarotenoids showed the markedly lowered levels of β-carotene (74 %) and lutein (72 %) along with the changed levels of two β-carotene (C₄₀) cleavage products, a two-fold increase of β-ionone (C₁₃) and de novo generation of β-cyclocitral (C₁₀) at lower levels, compared with non-transgenic rice plants. It suggests that β-carotene could be the principal substrate being cleaved at 9–10 (9′–10′) for β-ionone and 7–8 (7′–8′) positions for β-cyclocitral by AtCCD4. This study is in planta report on the generation of apocarotenal volatiles from carotenoid substrates via cleavage by AtCCD4. We further verified that the production of these volatiles was due to the action of exogenous AtCCD4 and not the expression of endogenous rice CCD genes (OsCCD1, 4a, and 4b).     

Analogs of host-specific phytotoxin produced by Helminthosporium maydis,race T: I. Synthesis

Fourteen analogs of the host-specific corn phytotoxin (T toxin) obtained from cultures of the fungal plant pathogen, Helminthosporium maydis, race T, were synthesized. Addition of difunctional Grignard reagents to aldehyde intermediates resulted in shorter versions (C₁₅–C₂₆) of native toxin (C₃₅–C₄₅), containing the β-polyketol functions which appear to account for the specificity and very high toxicity (10^?8–10^?9M) of T toxin toward certain corn varieties.     

Complete mitochondrial genomes of the Japanese pink coral (Corallium elatius) and the Mediterranean red coral (Corallium rubrum): a reevaluation of the phylogeny of the family Coralliidae based on molecular data

Precious corals are soft corals belonging to the family Coralliidae (Anthozoa: Octocorallia: Alcyonacea) and class Anthozoa, whose skeletal axes are used for jewelry.The family Coralliidae includes ca. 40 species and was originally thought to comprise of the single genus Corallium. In 2003, Corallium was split into two genera, Corallium and Paracorallium, and seven species were moved to this newly identified genus on the bases of morphological features. Previously, we determined the complete mitochondrial genome sequence of two precious corals Paracorallium japonicum and Corallium konojoi, in order to clarify their systematic positions. The two genomes showed high nucleotide sequence identity, but their gene order arrangements were not identical. Here, we determined three complete mitochondrial genome sequences from the one specimen of Mediterranean Corallium rubrum and two specimens of Corallium elatius coming from Kagoshima (South Japan). The circular mitochondrial genomes of C. rubrum and C. elatius are 18,915 bp and 18,969–18,970 bp in length, respectively, and encode 14 typical octocorallian protein-coding genes (nad1–6, nad4L, cox1–3, cob, atp6, atp8, and mtMutS, which is an octocoral-specific mismatch repair gene homologue), two ribosomal RNA genes (rns and rnl), and one transfer RNA (trnM). The overall nucleotide differences between C. konojoi and each C. elatius haplotype (T2007 and I2011) are only 10 and 11 nucleotides, respectively; this degree of similarity indicates that C. elatius and C. konojoi are very closely related species. Notably, the C. rubrum mitochondrial genome shows more nucleotide sequence identity to P. japonicum (99.5%) than to its congeneric species C. konojoi (95.3%) and C. elatius (95.3%). Moreover, the gene order arrangement of C. rubrum was the same as that of P. japonicum, while that of C. elatius was the same as C. konojoi. Phylogenetic analysis based on three mitochondrial genes from 24 scleraxonian species shows that the family Coralliidae is separated into two distinct groups, recovering Corallium as a paraphyletic genus. Our results indicate that the currently accepted generic classification of Coralliidae should be reconsidered.     

Analogs of host-specific phytotoxin produced by Helminthosporium maydis,race T: II. Biological activities

Inhibition of dark CO₂ fixation by susceptible corn leaves was used to compare the relative toxicity of synthetic analogs with that of the host-specific phytotoxin produced by the fungal corn pathogen, Helminthosporium maydis, race T. Analogs with C₁₅, C₂₅, or C₂₆ chain lengths and 1,5-dioxo-3-hydroxy functions were only slightly less toxic (2–6 × 10^?7M) than native T toxin (C₃₅–C₄₅ chain lengths) or its individual components (3 × 10^?8M). Like native toxin, analogs were host-specific in that they did not inhibit dark CO₂ fixation in leaf tissue of resistant corn at concentrations 10²–10³ times greater than those effective with susceptible corn. These findings support the structures previously proposed for native T toxin.     

Preparation of selective and segmentally labeled single-stranded DNA for NMR by self-primed PCR and asymmetrical endonuclease double digestion

We demonstrate a new, efficient and easy-to-use method for enzymatic synthesis of (stereo-)specific and segmental ¹³C/¹⁵N/²H isotope-labeled single-stranded DNA in amounts sufficient for NMR, based on the highly efficient self-primed PCR. To achieve this, new approaches are introduced and combined. (i) Asymmetric endonuclease double digestion of tandem-repeated PCR product. (ii) T4 DNA ligase mediated ligation of two ssDNA segments. (iii) In vitro dNTP synthesis, consisting of in vitro rNTP synthesis followed by enzymatic stereo-selective reduction of the C2′ of the rNTP, and a one-pot add-up synthesis of dTTP from dUTP. The method is demonstrated on two ssDNAs: (i) a 36-nt three-way junction, selectively ¹³C₉/¹⁵N₃/²H_{(1′,2″,3′,4′,5′,5″)}-dC labeled and (ii) a 39-nt triple-repeat three-way junction, selectively ¹³C₉/¹⁵N₃/²H_{(1′,2″,3′,4′,5′,5″)}-dC and ¹³C₉/¹⁵N₂/²H_{(1′,2″,3′,4′,5′,5″)}-dT labeled in segment C20-C39. Their NMR spectra show the spectral simplification, while the stereo-selective ²H-labeling in the deoxyribose of the dC-residues, straightforwardly provided assignment of their C1′–H2′ and C2′–H2′ resonances. The labeling protocols can be extended to larger ssDNA molecules and to more than two segments.     

Exposure to foodborne and orofecal microbes versus airborne viruses in relation to atopy and allergic asthma: epidemiological study

ObjectiveTo investigate if markers of exposure to foodborne and orofecal microbes versus airborne viruses are associated with atopy and respiratory allergies.DesignRetrospective case-control study.Participants240 atopic cases and 240 non-atopic controls from a population sample of 1659 participants, all Italian male cadets aged 17-24.SettingAir force school in Caserta, Italy.ResultsCompared with controls there was a lower prevalence of T gondii (26% v 18%, P=0.027), hepatitis A virus (30% v 16%, P=0.004), and H pylori (18% v 15%, P=0.325) in atopic participants. Adjusted odds ratios of atopy decreased with a gradient of exposure to H pylori, T gondii, and hepatitis A virus (none, odds ratio 1; one, 0.70; two or three, 0.37; P for trend=0.000045) but not with cumulative exposure to the other viruses. Conversely, total IgE concentration was not independently associated with any infection. Allergic asthma was rare (1/245, 0.4%) and allergic rhinitis infrequent (16/245, 7%) among the participants (245/1659) exposed to at least two orofecal and foodborne infections (H pylori, T gondii, hepatitis A virus).ConclusionRespiratory allergy is less frequent in people heavily exposed to orofecal and foodborne microbes. Hygiene and a westernised, semisterile diet may facilitate atopy by influencing the overall pattern of commensals and pathogens that stimulate the gut associated lymphoid tissue thus contributing to the epidemic of allergic asthma and rhinitis in developed countries.     

Biosynthetic relations between protoberberine-, benzo(C)phenanthridine- and B-secoprotoberberine type alkaloids in Corydalis incisa

The biosynthetic relations between protoberberine-, benzo[C]phenanthridine- and B-secoprotoberberine type alkaloids were demonstrated by use of (±)-tetrahydrocoptisine-[8,14-³H HCl, (±)-tetrahydrocorysamine-[8,14-³H]HCl and corynoline-[6-³H]HCl in Corydalis incisa, and the following results were presented. (±)-Tetrahydrocoptisine was converted to corynoline, corydalic acid methyl ester and corydamine hydrochloride. (±)-Tetrahydrocorysamine was converted to corynoline and corydalic acid methyl ester. Evidence that N-methyl-3-[6′-(3′,4′-methylenedioxyphenethylalcohol)]-4-methyl-7,8-methylenedioxy-1,2,3,4-tetrahydroisoquinoline-[α-³H] HCl was incorporated into corynoline-[11-³H] indicates the occurrence of the ring fission at C₆-N followed by linking ofthe C₆ and C₁₃ positions in (±)-tetrahydrocoptisine and (±)-tetrahydrocorysamine, and suggests the participation of one of two possible intermediates in the biosynthesis of these alkaloids.     

Chemical characterization of the lipophilic extract of Hydrilla verticillata: a widely spread aquatic weed

The composition of the lipophilic extract from Hydrilla verticillata, the common aquatic weed collected from Sasthamkotta Lake, the largest freshwater lake in Kerala, south of the west coast of India, was investigated. The lake is a designated wetland of international importance under the Ramsar Convention since 2002. GC-MS study of the unsaponifiable lipophilic extract of H. verticillata confirmed the presence of 3,5,11,15-tetramethyl 1- hexadecen-3-ol (C₂₀H₄₀O) and phytol (C₂₀H₄₀O) as major components, and their structures were elucidated. Phytol and 3,5,11,15-tetramethyl 1- hexadecen3-ol are the two isomers of the diterpeneol (C₂₀H₄₀O) found in the unsaponifible lipophilic extract of H. verticillata and are formed by the hydrolysis of the alcohol moiety of chlorophyll. On quantification, an appreciable concentration of phytol (6.39 g?Kg^?1) was estimated. The feasibility to utilize H. verticillata to produce phytol is to be addressed by further studies since H. verticillata is considered as one of the world’s fast widely spread aquatic weeds on account of its numerous mechanisms of vegetative reproductions.     

Substrate specificity of the epoxidation reaction in sex pheromone biosynthesis of the Japanese giant looper (Lepidoptera: Geometridae)

Female moths of the Japanese giant looper (Ascotis selenaria cretacea, Lepidoptera: Geometridae) secrete (Z,Z)-6,9-cis-3,4-epoxynonadecadiene as a sex pheromone component. To the pheromone glands of the decapitated females, [19,19,19-D₃](Z,Z,Z)-3,6,9-nonadecatriene was applied after an injection of pheromone biosynthesis activating neuropeptide. GC-MS analysis of the gland extract showed its specific conversion into the pheromonal cis-3,4-epoxide indicating that the C₁₉ triene which had been identified in the gland was a precursor of the pheromone. In order to examine the substrate specificity of the enzyme catalyzing this epoxidation step, several unsaturated hydrocarbons not occurring in the gland were applied to it. Not only (Z,Z,Z)-3,6,9-trienes with varying chain lengths (C₁₇, C₁₈ and C₂₀ to C₂₂) but (Z,Z)-3,6-dienes (C₁₇, C₁₉ and C₂₀) were converted into the corresponding cis-3,4-epoxides in a rather good yield, while no 6,7- and 9,10-epoxides could be detected. (Z)-3-Nonadecene was also changed to the cis-epoxide, but (E)-3-, (Z)-2- and (Z)-4-double bonds in the C₁₉ chain were not oxidized. These in vivo experiments revealed that the monooxygenase regiospecifically attacked the (Z)-3-double bond of straight chain hydrocarbons regardless of their length and degree of unsaturation.