Production of flavours and fragrances via bioreduction of (4R)-(-)-carvone and (1R)-(-)-myrtenal by non-conventional yeast whole-cells

As part of a program aiming at the selection of yeast strains which might be of interest as sources of natural flavours and fragrances, the bioreduction of (4R)-(-)-carvone and (1R)-(-)-myrtenal by whole-cells of non-conventional yeasts (NCYs) belonging to the genera Candida, Cryptococcus, Debaryomyces, Hanseniaspora, Kazachstania, Kluyveromyces, Lindnera, Nakaseomyces, Vanderwaltozyma and Wickerhamomyces was studied. Volatiles produced were sampled by means of headspace solid-phase microextraction (SPME) and the compounds were analysed and identified by gas chromatography-mass spectroscopy (GC-MS). Yields (expressed as % of biotransformation) varied in dependence of the strain. The reduction of both (4R)-(-)-carvone and (1R)-(-)-myrtenal were catalyzed by some ene-reductases (ERs) and/or carbonyl reductases (CRs), which determined the formation of (1R,4R)-dihydrocarvone and (1R)-myrtenol respectively, as main flavouring products. The potential of NCYs as novel whole-cell biocatalysts for selective biotransformation of electron-poor alkenes for producing flavours and fragrances of industrial interest is discussed.

Identification of 1,8-cineole, borneol, camphor, and thujone as anti-inflammatory compounds in a Salvia officinalis L. infusion using human gingival fibroblasts

Drinking or gargling Salvia officinalis L. infusion (sage infusion) is thought to soothe a sore throat, tonsillitis, and inflamed, red gums, although structure-based scientific evidence for the key anti-inflammatory compounds in sage infusion is scarce. Human gingival fibroblasts (HGF-1) were treated with sage infusion (SI) or SI fractions containing either its volatile components and water (aqueous distillate, AD) or its dry matter (DM) for six hours. SI, AD, and DM reduced a mean phorbol-12-myristate-13-acetate/ionomycin (PMA/I)-stimulated release of the pro-inflammatory interleukins IL-6 and IL-8 by more than 50% (p < 0.05). Cellular uptake experiments and subsequent GC-MS analysis using stable-isotope-labeled internal standards revealed the presence of 1,8-cineole, borneol, camphor, and α-/β-thujone in SI-treated cells; LC-MS analysis demonstrated the presence of rosmarinic acid. A significant, more than 50% mean inhibition of PMA/I-induced IL-6 and IL-8 release was demonstrated for the volatile compounds 1,8-cineole, borneol, camphor, and thujone, but not for the nonvolatile rosmarinic acid when applied in concentrations representative of sage infusion. Therefore, the volatile compounds were found to be more effective than rosmarinic acid. 1,8-Cineole, borneol, camphor, and α-/β-thujone chiefly contribute to the anti-inflammatory activity of sage infusion in human gingival fibroblasts.

Rapid "breath-print" of liver cirrhosis by proton transfer reaction time-of-flight mass spectrometry. A pilot study

The aim of the present work was to test the potential of Proton Transfer Reaction Time-of-Flight Mass Spectrometry (PTR-ToF-MS) in the diagnosis of liver cirrhosis and the assessment of disease severity by direct analysis of exhaled breath. Twenty-six volunteers have been enrolled in this study: 12 patients (M/F 8/4, mean age 70.5 years, min-max 42-80 years) with liver cirrhosis of different etiologies and at different severity of disease and 14 healthy subjects (M/F 5/9, mean age 52.3 years, min-max 35-77 years). Real time breath analysis was performed on fasting subjects using a buffered end-tidal on-line sampler directly coupled to a PTR-ToF-MS. Twelve volatile organic compounds (VOCs) resulted significantly differently in cirrhotic patients (CP) compared to healthy controls (CTRL): four ketones (2-butanone, 2- or 3- pentanone, C8-ketone, C9-ketone), two terpenes (monoterpene, monoterpene related), four sulphur or nitrogen compounds (sulfoxide-compound, S-compound, NS-compound, N-compound) and two alcohols (heptadienol, methanol). Seven VOCs (2-butanone, C8-ketone, a monoterpene, 2,4-heptadienol and three compounds containing N, S or NS) resulted significantly differently in compensate cirrhotic patients (Child-Pugh A; CP-A) and decompensated cirrhotic subjects (Child-Pugh B+C; CP-B+C). ROC (Receiver Operating Characteristic) analysis was performed considering three contrast groups: CP vs CTRL, CP-A vs CTRL and CP-A vs CP-B+C. In these comparisons monoterpene and N-compound showed the best diagnostic performance.

CONCLUSIONS

Breath analysis by PTR-ToF-MS was able to distinguish cirrhotic patients from healthy subjects and to discriminate those with well compensated liver disease from those at more advanced severity stage. A breath-print of liver cirrhosis was assessed for the first time.

Biochemical characteristics of a novel vegetative tissue geraniol acetyltransferase from a monoterpene oil grass (Palmarosa, Cymbopogon martinii var. Motia) leaf

Plants synthesize volatile alcohol esters on environmental insult or as metabolic induction during flower/fruit development. However, essential oil plants constitutively produce them as the oil constituents. Their synthesis is catalyzed by BAHD family enzymes called alcohol acyltransferases (AATs). However, no AAT has been characterized from plant foliage synthesizing acyclic monoterpenoids containing essential oils. Therefore, we have purified and biochemically characterized a geraniol: acetyl coenzyme A acetyltransferase (GAAT) from Palmarosa aroma grass (Cymbopogon martinii) leaf. MALDI-assisted proteomic study of the 43kDa monomeric enzyme revealed its sequence motif novelties e.g. relaxed conservation at Phe and Trp in DFGWG'. This suggests permissiveness of variations in the conserved motif without loss of catalytic ability. Also, some new conserved/semi-conserved motifs of AATs were recognized. The GAAT k(cat)/K(m) values (300-700M(-1)s(-1)) were low (a generic characteristic for secondary metabolism enzyme) but higher than those of some floral AATs. Wide substrate acceptability for catalyzing acetylation of diverse primary alcohols (chain of ≥C(6)) implied its catalytic description as a 'primary aliphatic alcohol acetyltransferase'. It signifies metabolic ability to deliver diverse aroma esters, should the acceptor alcohols be available in planta. To our knowledge, this is the first report of detailed kinetics of a vegetal monoterpenol acyltransferase.

Functional characterization of myrcene hydroxylases from two geographically distinct Ips pini populations

Ips pini bark beetles use myrcene hydroxylases to produce the aggregation pheromone component, ipsdienol, from myrcene. The enantiomeric ratio of pheromonal ipsdienol is an important prezygotic mating isolation mechanism of I. pini and differs among geographically distinct populations. We explored the substrate and product ranges of myrcene hydroxylases (CYP9T2 and CYP9T3) from reproductively-isolated western and eastern I. pini. The two cytochromes P450 share 94% amino acid identity. CYP9T2 mRNA levels were not induced in adults exposed to myrcene-saturated atmosphere. Functional assays of recombinant enzymes showed both hydroxylated myrcene, (+)- and (-)-α-pinene, 3-carene, and R-(+)-limonene, but not α-phellandrene, (-)-β-pinene, γ-terpinene, or terpinolene, with evidence that CYP9T2 strongly preferred myrcene over other substrates. They differed in the enantiomeric ratios of ipsdienol produced from myrcene, and in the products resulting from different α-pinene enantiomers. These data provide new information regarding bark beetle pheromone evolution and factors affecting cytochrome P450 structure-function relationships.

Identification of genes in Thuja plicata foliar terpenoid defenses

Thuja plicata (western redcedar) is a long-lived conifer species whose foliage is rarely affected by disease or insect pests, but can be severely damaged by ungulate browsing. Deterrence to browsing correlates with high foliar levels of terpenoids, in particular the monoterpenoid α-thujone. Here, we set out to identify genes whose products may be involved in the production of α-thujone and other terpenoids in this species. First, we generated a foliar transcriptome database from which to draw candidate genes. Second, we mapped the storage of thujones and other terpenoids to foliar glands. Third, we used global expression profiling to identify more than 600 genes that are expressed at high levels in foliage with glands, but can either not be detected or are expressed at low levels in a natural variant lacking foliar glands. Fourth, we used in situ RNA hybridization to map the expression of a putative monoterpene synthase to the epithelium of glands and used enzyme assays with recombinant protein of the same gene to show that it produces sabinene, the monoterpene precursor of α-thujone. Finally, we identified candidate genes with predicted enzymatic functions for the conversion of sabinene to α-thujone. Taken together, this approach generated both general resources and detailed functional characterization in the identification of genes of foliar terpenoid biosynthesis in T. plicata.

Secondary metabolites and antioxidant capacities of Waldheimia glabra (Decne.) Regel from Nepal

BACKGROUND

The phenolic content, volatile compound fingerprint and antioxidant capacity of Waldheimia glabra (Decne.) Regel (Asteraceae), a wild plant from the Himalayan mountains used in Sherpa religious rituals and in traditional medicine, were determined for the first time to investigate its suitability as a source of natural antioxidants.

RESULTS

The total phenolic content and antioxidant capacity of dried and powdered plants from two different altitudes (5000 and 5200 m above sea level) in Khumbu Valley, Nepal were estimated by the Folin-Ciocalteu and 2,2-diphenyl-1-picrylhydrazyl radical methods respectively. The volatile organic compound (VOC) fingerprints from leafing plants (in vivo and in situ VOC sampling) and from dried plant samples were evaluated by headspace solid phase microextraction. The results indicated that W. glabra was a good source of phenolics with antioxidant properties. A correlation between total phenolic content and antioxidant capacity was found (r² = 0.9111). Seychellene, a volatile compound that characterises patchouli oil, was detected for the first time in a species of the Asteraceae family.

CONCLUSION

Waldheimia glabra was proved to be a good source of antioxidants, partially supporting its traditional uses. Further studies aimed at deepening knowledge on W. glabra bioactivity and its possible uses will be of interest, considering the lack of proper scientific awareness regarding these aspects.

Effects of the virus satellite gene βC1 on host plant defense signaling and volatile emission

Tomato Yellow Leaf Curl China virus spreads together with its invasive vector, the silverleaf whitefly B biotype, which exhibits higher growth rates on infected plants. Previous studies indicate that the virus satellite gene βC1 accounts for the visible symptoms of infection and inhibits the constitutive expression of jasmonic acid (JA)--a phytohormone involved in plant defense against whiteflies--and of some JA-regulated genes. Here we present new details of the effects of on plant signaling and defense, obtained with (non-host) transgenic Arabidopsis thaliana and Nicotiana benthamiana plants. We found that JA induction in response to wounding was reduced in plants expressing βC1. This result implies that βC1 acts on conserved plant regulation mechanisms and might impair the entire JA defense pathway. Furthermore, transformed N. benthamiana plants exhibited elevated emissions of the volatile compound linalool, suggesting that βC1 also influences plant-derived olfactory cues available to vector and non-vector insects.

Citral induces auxin and ethylene-mediated malformations and arrests cell division in Arabidopsis thaliana roots

Citral is a linear monoterpene which is present, as a volatile component, in the essential oil of several different aromatic plants. Previous studies have demonstrated the ability of citral to alter the mitotic microtubules of plant cells, especially at low concentrations. The changes to the microtubules may be due to the compound acting directly on the treated root and coleoptile cells or to indirect action through certain phytohormones. This study, performed in Arabidopsis thaliana, analysed the short-term effects of citral on the auxin content and mitotic cells, and the long-term effects of these alterations on root development and ethylene levels. The results of this study show that citral alters auxin content and cell division and has a strong long-term disorganising effect on cell ultra-structure in A. thaliana seedlings. Its effects on cell division, the thickening of the cell wall, the reduction in intercellular communication, and the absence of root hairs confirm that citral is a strong phytotoxic compound, which has persistent effects on root development.

Metabolic engineering of plant monoterpenes, sesquiterpenes and diterpenes--current status and future opportunities

Terpenoids (a.k.a. isoprenoids) represent the most diverse class of natural products found in plants, with tens of thousands of reported structures. Plant-derived terpenoids have a multitude of pharmaceutical and industrial applications, but the natural resources for their extraction are often limited and, in many cases, synthetic routes are not commercially viable. Some of the most valuable terpenoids are not accumulated in model plants or crops, and genetic resources for breeding of terpenoid natural product traits are thus poorly developed. At present, metabolic engineering, either in the native producer or a heterologous host, is the only realistic alternative to improve yield and accessibility. In this review article, we will evaluate the state of the art of modulating the biosynthetic pathways for the production of mono-, sesqui- and diterpenes in plants.

Functional genomics reveals that a compact terpene synthase gene family can account for terpene volatile production in apple

Terpenes are specialized plant metabolites that act as attractants to pollinators and as defensive compounds against pathogens and herbivores, but they also play an important role in determining the quality of horticultural food products. We show that the genome of cultivated apple (Malus domestica) contains 55 putative terpene synthase (TPS) genes, of which only 10 are predicted to be functional. This low number of predicted functional TPS genes compared with other plant species was supported by the identification of only eight potentially functional TPS enzymes in apple 'Royal Gala' expressed sequence tag databases, including the previously characterized apple (E,E)-α-farnesene synthase. In planta functional characterization of these TPS enzymes showed that they could account for the majority of terpene volatiles produced in cv Royal Gala, including the sesquiterpenes germacrene-D and (E)-β-caryophyllene, the monoterpenes linalool and α-pinene, and the homoterpene (E)-4,8-dimethyl-1,3,7-nonatriene. Relative expression analysis of the TPS genes indicated that floral and vegetative tissues were the primary sites of terpene production in cv Royal Gala. However, production of cv Royal Gala floral-specific terpenes and TPS genes was observed in the fruit of some heritage apple cultivars. Our results suggest that the apple TPS gene family has been shaped by a combination of ancestral and more recent genome-wide duplication events. The relatively small number of functional enzymes suggests that the remaining terpenes produced in floral and vegetative and fruit tissues are maintained under a positive selective pressure, while the small number of terpenes found in the fruit of modern cultivars may be related to commercial breeding strategies.

The tomato cis-prenyltransferase gene family

cis-prenyltransferases (CPTs) are predicted to be involved in the synthesis of long-chain polyisoprenoids, all with five or more isoprene (C5) units. Recently, we identified a short-chain CPT, neryl diphosphate synthase (NDPS1), in tomato (Solanum lycopersicum). Here, we searched the tomato genome and identified and characterized its entire CPT gene family, which comprises seven members (SlCPT1-7, with NDPS1 designated as SlCPT1). Six of the SlCPT genes encode proteins with N-terminal targeting sequences, which, when fused to GFP, mediated GFP transport to the plastids of Arabidopsis protoplasts. The SlCPT3-GFP fusion protein was localized to the cytosol. Enzymatic characterization of recombinant SlCPT proteins demonstrated that SlCPT6 produces Z,Z-FPP, and SlCPT2 catalyzes the formation of nerylneryl diphosphate while SlCPT4, SlCPT5 and SlCPT7 synthesize longer-chain products (C25-C55). Although no in vitro activity was demonstrated for SlCPT3, its expression in the Saccharomyces cerevisiae dolichol biosynthesis mutant (rer2) complemented the temperature-sensitive growth defect. Transcripts of SlCPT2, SlCPT4, SlCPT5 and SlCPT7 are present at low levels in multiple tissues, SlCPT6 is exclusively expressed in red fruit and roots, and SlCPT1, SlCPT3 and SlCPT7 are highly expressed in trichomes. RNAi-mediated suppression of NDPS1 led to a large decrease in β-phellandrene (which is produced from neryl diphosphate), with greater reductions achieved with the general 35S promoter compared to the trichome-specific MKS1 promoter. Phylogenetic analysis revealed CPT gene families in both eudicots and monocots, and showed that all the short-chain CPT genes from tomato (SlCPT1, SlCPT2 and SlCPT6) are closely linked to terpene synthase gene clusters.

Variation in carbon availability, defense chemistry and susceptibility to fungal invasion along the stems of mature trees

If carbon (C) sinks withdraw carbohydrates as they are transported along tree stems, carbohydrate availability may depend on local sink strength and distance from sources. Defenses, including monoterpenes--a major component of resin--limit the invasibility of pines. Since carbohydrate reserves fund monoterpene synthesis, we hypothesized that monoterpene concentrations in pine stems would decrease from the crown to the lower stem, and susceptibility to fungal infection would increase. Here, we measured carbohydrate and monoterpene concentrations along the stems of lodgepole pine trees (Pinus contorta var. latifolia) before inoculating with a blue-stain fungus at different heights. After 6 wk, we assessed tree responses to fungal infection based on lesion length and carbohydrate mobilization. Concentrations of carbohydrates and monoterpenes in the phloem before inoculation decreased with distance from the crown, whereas lesion lengths after inoculation increased. However, trees mobilized sugars in response to fungal infection such that carbohydrate reserves near lesions were similar at all heights. Despite C mobilization, the lower stem was more vulnerable than the upper stem. Consistent with predictions based on sink-source relationships, vulnerability occurred where carbohydrates were less available, and likely resulted from C withdrawal by sinks higher in the supply chain.

Natural selection on floral volatile production in Penstemon digitalis: highlighting the role of linalool

Natural selection is thought to have shaped the evolution of floral scent; however, unlike other floral characters, we have a rudimentary knowledge of how phenotypic selection acts on scent. We found that floral scent was under stronger selection than corolla traits such as flower size and flower color in weakly scented Penstemon digitalis. Our results suggest that to understand evolution in floral phenotypes, including scent in floral selection, studies are crucial. For P. digitalis, linalool was the direct target of selection in the scent bouquet. Therefore, we determined the enantiomeric configuration of linalool because interacting insects may perceive the enantiomers differentially. We found that P. digitalis produces only (S)-(+)-linalool and, more interestingly, it is also taken up into the nectar. Because the nectar is scented and flavored with (S)-(+)-linalool, it may be an important cue for pollinators visiting P. digitalis flowers.

Characterization of the plastidial geraniol synthase from Madagascar periwinkle which initiates the monoterpenoid branch of the alkaloid pathway in internal phloem associated parenchyma

Madagascar periwinkle (Catharanthus roseus [L.] G. Don, Apocynaceae) produces monoterpene indole alkaloids (MIAs), secondary metabolites of high interest due to their therapeutic value. A key step in the biosynthesis is the generation of geraniol from geranyl diphosphate (GPP) in the monoterpenoid branch of the MIA pathway. Here we report on the cloning and functional characterization of C. roseus geraniol synthase (CrGES). The full-length CrGES was over-expressed in Escherichia coli and the purified recombinant protein catalyzed the conversion of GPP into geraniol with a K(m) value of 58.5 μM for GPP. In vivo CrGES activity was evaluated by heterologous expression in a Saccharomyces cerevisiae strain mutated in the farnesyl diphosphate synthase gene. Analysis of culture extracts by gas chromatography-mass spectrometry confirmed the excretion of geraniol into the growth medium. Transient transformation of C. roseus cells with a Yellow Fluorescent Protein-fusion construct revealed that CrGES is localized in plastid stroma and stromules. In aerial plant organs, RNA in situ hybridization showed specific labeling of CrGES transcripts in the internal phloem associated parenchyma as observed for other characterized genes involved in the early steps of MIA biosynthesis. Finally, when cultures of Catharanthus cells were treated with the alkaloid-inducing hormone methyl jasmonate, an increase in CrGES transcript levels was observed. This observation coupled with the tissue-specific expression and the subcellular compartmentalization support the idea that CrGES initiates the monoterpenoid branch of the MIA biosynthetic pathway.

Identification of CYP isoforms involved in the metabolism of thymol and carvacrol in human liver microsomes (HLMs)

Carvacrol and thymol are phenolic compounds with similar structures isolated from many aromatic plants, and have been demonstrated to exert multiple pharmacological effects. The metabolic and pharmacokinetic behaviour of thymol and carvacrol has received much attention. Carvacrol and thymol have been demonstrated to undergo phase I metabolism such as hydroxylation reaction. However, drug-metabolizing enzymes involved in this process remain unclear. Given that cytochrome P450s (CYPs) are involved in most phase I metabolism, the aim of the present study was to investigate the role of CYPs in the metabolism of thymol and carvacrol. After incubation with human liver microsomes (HLMs) in the presence of NADPH, a new metabolite and two metabolites were detected for thymol and carvacrol, respectively. A combination of chemical inhibition studies and assays with recombinant CYP isoforms demonstrated that CYP2A6 was the predominant drug-metabolizing enzyme involved in the metabolism of thymol and carvacrol. All these results remind the researchers that special attention should be paid on pharmacokinetic and clinical outcomes when thymol or carvacrol was co-administrated with other compounds mainly undergoing CYP2A6-mediated metabolism.

Anti-Candida albicans effectiveness of citral and investigation of mode of action

CONTEXT

Candidiasis is a mycosis caused by Candida species, which is of clinical importance due to the increase in resistant yeasts. Candida infection has been a serious health problem due to the inappropriate use of antibiotics. Therefore, it is necessary to study molecules with an antifungal action. Citral is a monoterpene with known pharmacological properties, including antimicrobial action.

OBJECTIVE

The aim of this work was to determine the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of citral and the probable mode of action.

MATERIALS AND METHODS

The MIC of citral was determined by the broth microdilution method using Sabouraud dextrose medium. Additionally, the interference of citral in cell wall (sorbitol assay) and the binding of citral to ergosterol and cholesterol were studied, carried out by broth microdilution method.

RESULTS

The MIC and MFC of citral were 512 and 1024 µg/mL, respectively. The MIC of amphotericin B was 1 µg/mL. The mechanism of action did not involve either the cell wall or ergosterol. However, the presence of cholesterol increased the MIC of citral to 1024 µg/mL, indicating there is some interaction between citral and cholesterol. Amphotericin B was used as the positive control, and it showed a high MIC in the presence of ergosterol (32 µg/mL), while in the presence of cholesterol MIC increased to 4 µg/mL.

CONCLUSION

Citral inhibits the growth of C. albicans. The probable mechanism of action did not involve the cell wall or ergosterol. Citral is able to interact with cholesterol. More studies are necessary to describe their effects completely.

Plasma membrane potential depolarization and cytosolic calcium flux are early events involved in tomato (Solanum lycopersicon) plant-to-plant communication

Tomato plants respond to herbivory by emitting volatile organic compounds (VOCs), which are released into the surrounding atmosphere. We analyzed the tomato herbivore-induced VOCs and tested the ability of tomato receiver plants to detect tomato donor volatiles by analyzing early responses, including plasma membrane potential (V(m)) variations and cytosolic calcium ([Ca²⁺](cyt)) fluxes. Receiver tomato plants responded within seconds to herbivore-induced VOCs with a strong V(m) depolarization, which was only partly recovered by fluxing receiver plants with clean air. Among emitted volatiles, we identified by GC-MS some green leaf volatiles (GLVs) such as (E)-2-hexenal, (Z)-3-hexenal, (Z)-3-hexenyl acetate, the monoterpene α-pinene, and the sesquiterpene β-caryophyllene. GLVs were found to exert the stronger V(m) depolarization, when compared to α-pinene and β-caryophyllene. Furthermore, V(m) depolarization was found to increase with increasing GLVs concentration. GLVs were also found to induce a strong [Ca²⁺](cyt) increase, particularly when (Z)-3-hexenyl acetate was tested both in solution and with a gas. On the other hand, α-pinene and β-caryophyllene, which also induced a significant V(m) depolarization with respect to controls, did not exert any significant effect on [Ca²⁺](cyt) homeostasis. Our results show for the first time that plant perception of volatile cues (especially GLVs) from the surrounding environment is mediated by early events, occurring within seconds and involving the alteration of the plasma membrane potential and the [Ca²⁺](cyt) flux.

[Cloning and expression regulation of 1-deoxy-D-xylulose-5-phosphate reductoisomerase cDNA from Alpinia officinarum]

The rhizome of Alpinia officinarum is a widely used Chinese herbal medicine. The essential oil in A. officinarum rhizome is mainly composed of 1, 8-cineole and other monoterpenes, as the major bioactive ingredients. In plants, monoterpenes are synthesized through the methylerythritol phosphate (MEP) pathway in the plastids, and 1-deoxy-D-xylulose 5-phosphate reductoisomerase (DXR) is an enzyme catalyzing a committed step of the MEP pathway. In the present study, the full-length cDNA encoding DXR was cloned from the rhizome of A. officinarum, using homology-based RT-PCR and rapid amplification of cDNA ends (RACE) techniques. The new cDNA was designated as AoDXR and submitted to GenBank to be assigned with an accession number HQ874658. The full-length cDNA of AoDXR was 1 670 bp containing a 1 419 bp open reading frame encoding a polypeptide of 472 amino acids with a calculated molecular mass of 51.48 kDa and an isoelectric point of 6.15. Bioinformatic analyses revealed that AoDXR showed extensive homology with DXRs from other plant species and contained a conserved plastids transit peptide, a Pro-rich region and two highly conserved NADPH-binding motifs in its N-terminal region characterized by all plant DXRs. The phylogenetic analysis revealed that AoDXR belonged to angiosperm DXRs. The structural modeling of AoDXR showed that AoDXR had the typical V-shaped structure of DXR proteins. The tissue expression pattern analysis indicated that AoDXR expressed strongly in leaves, weak in rhizomes of A. officinarum. Exogenous methyl jasmonate (MeJA) could enhance the expression of AoDXR and the production of 1, 8-cineole in A. officinarum rhizomes. The cloning and characterization of AoDXR will be helpful to reveal the molecular regulation mechanism of monoterpene biosynthesis in A. officinarum and provides a candidate gene for metabolic engineering in improving the medicinal quality of A. officinarum rhizome.

Mechanisms for eliminating monoterpenes of sagebrush by specialist and generalist rabbits

Pygmy rabbits (Brachylagus idahoensis) are one of only three vertebrates that subsist virtually exclusively on sagebrush (Artemisia spp.), which contains high levels of monoterpenes that can be toxic. We examined the mechanisms used by specialist pygmy rabbits to eliminate 1,8-cineole, a monoterpene of sagebrush, and compared them with those of cottontail rabbits (Sylvilagus nuttalli), a generalist herbivore. Rabbits were offered food pellets with increasing concentrations of cineole, and we measured voluntary intake and excretion of cineole metabolites in feces and urine. We expected pygmy rabbits to consume more, but excrete cineole more rapidly by using less-energetically expensive methods of detoxification than cottontails. Pygmy rabbits consumed 3-5 times more cineole than cottontails relative to their metabolic body mass, and excreted up to 2 times more cineole metabolites in their urine than did cottontails. Urinary metabolites excreted by pygmy rabbits were 20 % more highly-oxidized and 6 times less-conjugated than those of cottontails. Twenty percent of all cineole metabolites recovered from pygmy rabbits were in feces, whereas cottontails did not excrete fecal metabolites. When compared to other mammals that consume cineole, pygmy rabbits voluntarily consumed more, and excreted more cineole metabolites in feces, but they excreted less oxidized and more conjugated cineole metabolites in urine. Pygmy rabbits seem to have a greater capacity to minimize systemic exposure to cineole than do cottontails, and other cineole-consumers, by minimizing absorption and maximizing detoxification of ingested cineole. However, mechanisms that lower systemic exposure to cineole may come with a higher energetic cost in pygmy rabbits than in other mammalian herbivores.

Biodegradable polymer (PLGA) coatings featuring cinnamaldehyde and carvacrol mitigate biofilm formation

Biofilm-associated infections are one of the leading causes of death in the United States. Although infections may be treated with antibiotics, the overuse of antibiotics has led to the spread of antibiotic resistance. Many natural antimicrobial compounds derived from edible plants are safe for human use and target bacteria nonspecifically. Therefore, they may impair biofilm formation with less evolutionary pressure on pathogens. Here, we explore the use of two natural antimicrobial compounds, cinnamaldehyde (CA, from cinnamon) and carvacrol (CARV, from oregano), for biofilm prevention. We have fabricated and characterized films that incorporate CA and CARV into the biodegradable, FDA-approved polymer poly(lactic-co-glycolic acid), PLGA. The addition of CA and CARV to PLGA films not only adds antimicrobial activity but also changes the surface properties of the films, making them more hydrophilic and therefore more resistant to bacterial attachment. An addition of 0.1% CA to a PLGA film significantly impairs biofilm development by Staphylococcus aureus, and 0.1% CARV in PLGA significantly decreases biofilm formation by both Escherichia coli and S. aureus. Pseudomonas aeruginosa, which is less susceptible to CA and CARV, was not affected by the addition of 0.1% CA or CARV to the PLGA coatings; however, P. aeruginosa biofilm was significantly reduced by 1.0% CA. These results indicate that both CA and CARV could potentially be used in low concentrations as natural additives in polymer coatings for indwelling devices to delay colonization by bacteria.

Quantitative levels of Deficiens and Globosa during late petal development show a complex transcriptional network topology of B function

The transcriptional network topology of B function in Antirrhinum, required for petal and stamen development, is thought to rely on initial activation of transcription of DEFICIENS (DEF) and GLOBOSA (GLO), followed by a positive autoregulatory loop maintaining gene expression levels. Here, we show that the mutant compacta (co), whose vegetative growth and petal size are affected, plays a role in B function. Late events in petal morphogenesis such as development of conical cell area and scent emissions were reduced in co and def (nicotianoides) (def (nic) ), and absent in co def (nic) double mutants, suggesting a role for CO in petal identity. Expression of DEF was down-regulated in co but surprisingly GLO was not affected. We investigated the levels of DEF and GLO at late stages of petal development in the co, def (nic) and glo-1 mutants, and established a reliable transformation protocol that yielded RNAi-DEF lines. We show that the threshold levels of DEF or GLO required to obtain petal tissue are approximately 11% of wild-type. The relationship between DEF and GLO transcripts is not equal or constant and changes during development. Furthermore, down-regulation of DEF or GLO does not cause parallel down-regulation of the partner. Our results demonstrate that, at late stages of petal development, the B function transcriptional network topology is not based on positive autoregulation, and has additional components of transcriptional maintenance. Our results suggest changes in network topology that may allow changes in protein complexes that would explain the fact that not all petal traits appear early in development.

Response surface methodology as optimization strategy for asymmetric bioreduction of (4S)-(+)-carvone by Cryptococcus gastricus

Response surface methodology was applied in optimizing the asymmetric bioreduction of (4S)-(+)-carvone to dihydrocarvone (with low incidence of unsought side reactions) by using whole-cells of Cryptococcus gastricus. A factorial design (2(5)) including five independent variables was performed: X(1)=incubation time; X(2)=pH; X(3)=amount of whole-cells; X(4)=concentration of (4S)-(+)-carvone; X(5)=concentration of cofactor-recycling system. The utilization of glucose and glycerol as cofactor-recycling systems was checked. On the basis of the results of factorial design, three independent variables (X(1), X(3) and X(4)) out of five were further selected for performing a central composite design (CCD). First and second order polynomial equations obtained by CCD were used to select the optimal values of independent variables in order to maximize the bioreduction yield of (4S)-(+)-carvone and, at the same time, to minimize the occurrence of side reactions (i.e. further reduction of dihydrocarvone to dihydrocarveol).

Role of trichomes in defense against herbivores: comparison of herbivore response to woolly and hairless trichome mutants in tomato (Solanum lycopersicum)

Trichomes contribute to plant resistance against herbivory by physical and chemical deterrents. To better understand their role in plant defense, we systemically studied trichome morphology, chemical composition and the response of the insect herbivores Helicoverpa zea and Leptinotarsa decemlineata (Colorado potato beetle = CPB) on the tomato hairless (hl), hairy (woolly) mutants and wild-type Rutgers (RU) and Alisa Craig (AC) plants. Hairless mutants showed reduced number of twisted glandular trichomes (types I, IV, VI and VII) on leaf and stem compared to wild-type Rutgers (RU), while woolly mutants showed high density of non-glandular trichomes (types II, III and V) but only on the leaf. In both mutants, trichome numbers were increased by methyl jasmonate (MeJA), but the types of trichomes present were not affected by MeJA treatment. Glandular trichomes contained high levels of monoterpenes and sesquiterpenes. A similar pattern of transcript accumulation was observed for monoterpene MTS1 (=TPS5) and sesquiterpene synthase SST1 (=TPS9) genes in trichomes. While high density of non-glandular trichome on leaves negatively influenced CPB feeding behavior and growth, it stimulated H. zea growth. High glandular trichome density impaired H. zea growth, but had no effect on CPB. Quantitative real-time polymerase chain reaction (qRT-PCR) showed that glandular trichomes highly express protein inhibitors (PIN2), polyphenol oxidase (PPOF) and hydroperoxide lyase (HPL) when compared to non-glandular trichomes. The SlCycB2 gene, which participates in woolly trichome formation, was highly expressed in the woolly mutant trichomes. PIN2 in trichomes was highly induced by insect feeding in both mutant and wild-type plants. Thus, both the densities of trichomes and the chemical defenses residing in the trichomes are inducible.

Trail pheromone of the Argentine ant, Linepithema humile (Mayr) (Hymenoptera: Formicidae)

The Argentine ant (Linepithema humile) is recognized as one of the world's most damaging invasive species. One reason for the ecological dominance of introduced Argentine ant populations is their ability to dominate food and habitat resources through the rapid mobilization and recruitment of thousands of workers. More than 30 years ago, studies showed that (Z)-9-hexadecenal strongly attracted Argentine ant workers in a multi-choice olfactometer, suggesting that (Z)-9-hexadecenal might be the trail pheromone, or a component of a trail pheromone mixture. Since then, numerous studies have considered (Z)-9-hexadecenal as the key component of the Argentine ant trails. Here, we report the first chemical analyses of the trails laid by living Argentine ants and find that (Z)-9-hexadecenal is not present in a detectible quantity. Instead, two iridoids, dolichodial and iridomyrmecin, appear to be the primary chemical constituents of the trails. Laboratory choice tests confirmed that Argentine ants were attracted to artificial trails comprised of these two chemicals significantly more often than control trails. Although (Z)-9-hexadecenal was not detected in natural trails, supplementation of artificial dolichodial+iridomyrmecin trails with an extremely low concentraion of (Z)-9-hexadecenal did increase the efficacy of the trail-following behavior. In stark contrast with previous dogma, our study suggests that dolichodial and iridomyrmecin are major components of the Argentine ant trail pheromone. (Z)-9-hexadecenal may act in an additive manner with these iridoids, but it does not occur in detectable quantities in Argentine ant recruitment trails.