Decreased Liver Fatty Acid Δ‐6 and Δ‐5 Desaturase Activity in Obese Patients

Steatosis in obese nonalcoholic fatty liver disease (NAFLD) patients is a clinicopathological condition associated with depletion of n‐3 polyunsaturated fatty acids (PUFA), a feature that may be related to PUFA desaturation. Liver Δ‐6 and Δ‐5 desaturase (Δ‐6D and Δ‐5D) activities, homeostasis model assessment of insulin resistance (HOMA_IR), and ferric reducing ability of plasma (FRAP) were evaluated in 13 obese patients who underwent subtotal gastrectomy with gastro‐jejunal anastomosis in Roux‐en‐Y and 15 nonobese patients who underwent laparoscopic cholecystectomy (controls). Liver Δ‐6D and Δ‐5D activities in obese patients were 87% and 66% lower than controls (P < 0.001), respectively, with a 62% diminution in the Δ‐6D/Δ‐5D activity ratio (P < 0.02). Δ‐6D inversely correlated with both HOMA_IR (r = ?0.70, P < 0.0001) and oxidative stress assessed as the reciprocal value of FRAP (r = ?0.40, P < 0.05). Δ‐5D negatively correlated with HOMA_IR (r = ?0.48, P < 0.01) but not with FRAP^?1 (r = ?0.13, not significant). In conclusion, liver PUFA desaturation is diminished in obese NAFLD patients, in association with underlying insulin resistance and oxidative stress, which may play a role in altering lipid metabolism favoring fatty infiltration.     

Recent Results in the Search for New Molecules with Ambergris Odor

The synthesis of new odorant molecules is still a challenging task for the fragrance chemist, because now as ever it is difficult to predict the odor properties of small organic molecules. Therefore, certain tools, such as, e.g., lead‐structure optimization of existing odorants, are helpful techniques. In this article, we describe the synthesis and the odor properties of a new molecule derived by the so‐called ‘seco’ lead‐structure optimization of the ambergris compound Ambroxide^®. Based on these results, more representatives with similar structures have been synthesized and evaluated for their olfactory properties.     

Planar Chiral Iridium Complexes with the Δ‐TRISPHAT Anion: Toward the First Enantiopure o‐Quinone Methide π‐Complex

We describe the resolution of a planar chiral cationic iridium complex [Cp*Ir(η⁵‐2‐methyl‐oxodienyl)][OT f] ( 2 ) following the counterion strategy, where anion metathesis by Δ‐TRISPHAT generates the two diastereomers (pR, pS)‐[Cp*Ir(η⁵‐2‐methyl‐oxodienyl)][Δ‐TRISPHAT] ( 3a , 3a' ). Upon fractional crystallization both compounds were separated as confirmed by ¹H nuclear magnetic resonance (NMR) and circular dichroism studies recorded in solution. The latter represents the key‐complex precursors for the enantioselective synthesis of metallated o‐quinone methide complexes ( 4a , 4a' ). Chirality 25:449–454, 2013. © 2013 Wiley Periodicals, Inc.     

<Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated transformation and shoot regeneration in elite breeding lines of western shipper cantaloupe and honeydew melons (<Emphasis Type="Italic">Cucumis melo</Emphasis> L.)

A reliable Agrobacterium-mediated transformation and shoot regeneration protocol was developed for breeding lines of commercially important western-shipper cantaloupe and honeydew melons, ‘F39’ and ‘150’, respectively. Different media were tested to select a shoot regeneration system for each of three elite breeding lines ‘F39’, ‘141’ and ‘TMS’. Murashige &; Skoog (MS) basal medium supplemented with 1 mg l^?1 benzyladenine (BA), 0.26 mg l^?1 abscisic acid (ABA) and 0.8 mg l^?1 indole-3-acetic acid (IAA) was used for shoot regeneration from cotyledonary explants in ‘F39’ and ‘150’. Kanamycin sensitivity as well as Timentin^? and Clavamox^® were evaluated using wild-type ‘F39’ and ‘150’ cotyledons. Kanamycin concentrations of 200 and 150 mg l^?1 were chosen as the threshold levels for ‘F39’ and ‘150’, respectively. No significant differences were found between Timentin^? and Clavamox^® in ‘F39’; however, Clavamox^® reduced the incidence of vitrification and increased the frequency of shoot elongation in ‘150’. A. tumefaciens strain EHA105, harboring pCNL56 carrying neomycin phosphotransferase II (nptII) and gusA reporter genes, was selected to establish a transformation protocol for ‘F39’ and ‘150’. Putative transformants were evaluated using β-glucuronidase (GUS) histochemical assay, polymerase chain reaction (PCR) and Southern blot analyses. Based on these parameters, the transformation efficiency for cantaloupe ‘F39’ was 0.3% and that for honeydew ‘150’ was 0.5%.     

Influence of insecticide, wax and biofungicide treatments, applied to Pinus sylvestris and Picea abies, on the olfactory orientation of the large pine weevil, Hylobius abietis L. (Coleoptera: Curculionidae)

1 A four-arm olfactometer was used to test the effect of permethrin ‘Gori 920^®’ and the wax treatment ‘CereNat^® E30’ on the response of mature adult Hylobius abietis to olfactory stimuli from seedlings of Pinus sylvestris and Picea abies. 2 Also investigated in the olfactometer was the effect of Rotstop^®, a biofungicide for the control of Fomes root and butt rot, Heterobasidion annosum, on the responses of mature adult female H. abietis to stump material of both P. sylvestris and P. abies. 3 Hylobius abietis was significantly more attracted to untreated P. sylvestris seedlings compared to those treated with CereNat^® E30 or permethrin Gori 920^®. No differences in response to P. abies seedlings were found. 4 With Rotstop^®, no changes in the attractiveness of P. sylvestris stump material were found, but that of P. abies was significantly increased compared to untreated material.     

Further observations on rhythmic emission of fragrance in flowers

Observations regarding floral fragrance and the rhythmicity of its emission in four plant species are reported. In the case of flowers of Hoya carnosa R. Br. which are characterized by circadian rhythmicity of scentedness (R. Altenburger and P. Matile, 1988, Planta 174, 248–252), temperature compensation of the free-running period as well as persistence of oscillations in permanent darkness have been demonstrated. A hitherto unidentified component of fragrance turned out to be identical to an unusual sesquiterpene recently discovered in cardamom oil (B. Maurer et al., 1986, Tetrahedron Lett. 27, 2111–2112). In Stephanotis floribunda Brongs. the rhythmic emission of fragrance is circadian in nature, but in a constant environment the oscillations of individual components are increasingly asynchronous. In excised flowers of Odontoglossum constrictum Lindl. the diurnal oscillations observed in a natural photoperiod are abolished under constant environmental conditions. They are resumed upon the return to a 1212-h photoperiod. The absence of circadian control could also be demonstrated in excised flowers of Citrus medica L. In this species, too, the daily maxima of scent emission reappear upon the transfer of flowers to a 1212-h light/ dark cycle. Results obtained upon the comparative analysis of volatiles in the headspace above the flowers and in petal extract indicate that the relative abundance of an individual compound in the floral fragrance is not a function of differential volatility.Abbreviations DL 1212 h photoperiod - DD continuous darkness - GLC gas-liquid chromatography - LL continuous illumination The authors are indebted to R. Kaiser, Givaudon Corp.for kindly carrying out the identifikation of volatiles by gas-liquid chromalography/mass spectrometry.     

Arctic and North Atlantic Oscillation phase changes are recorded in the isotopes (δ18O and δ13C) of Cassiope tetragona plants

The Arctic and North Atlantic Oscillations (AO/NAO) are large‐scale annual modes of atmospheric circulation that have shifted in the last 30 years. Recent changes in arctic climate, including increasing surface air temperature, declining sea ice extent, and shifts in the amounts seasonality of precipitation are linked to the strong positive phase of the AO/NAO. Here, we show that phase changes in the AO/NAO are recorded in the isotopic (δ¹⁸O and Δ‐carbon isotope discrimination) characteristics of the long‐lived circum‐arctic plant, Cassiope tetragona, as summer rain has become a more important water source than snowmelt water which in turn has lead to decreases in Δ and reductions in plant stem growth. These isotopic records in C. tetragona may facilitate reconstructions of climate, plant–soil water relations, plant gas exchange attributes and a mechanistic understanding of growth responses to shifts in atmospheric circulation. If plant specimens were available for populations across the arctic as part of the International Polar Year, these archives could provide a circum‐arctic record of historical climate change and associated shifts in physiological plant performance and growth.     

Felicitometry: measuring the 'quality' in quality of life

Following Bernheim, ¹ 1 J.L. Bernheim. How to get serious answers to the serious question: ‘How have you been?’ Subjective quality of life (QOL) as an individual experiential emergent construct. Bioethics. 1998 ; 13 : 272 – 287 .
we examine aspects of ‘felicitometrics,’ ² 2 Jeremy Bentham (1748–1832) introduced the term ‘felicitometrics.’ He used the term ‘felicific calculus’ to describe methods for calculating the amounts of pleasure and pain consequent on particular courses of action: to wit, ‘Sum up all the values of all the pleasures on the one side and those of all the pains on the other. The balance, if it be on the side of pleasure, will give the good tendency of the act . . .’
the measurement of the ‘quality’ term in Quality of Life (QOL). Bernheim argued that overall QOL is best captured as the Gestalt ³ 3 Gestalts are unified wholes with the property that the arrangement of component features provides information not apparent in the features alone. The face provides an oft‐used example: Only by seeing the individual features of the face can one see the face as a whole, and only by seeing the face as a whole can one give meaning to its individual features.
of a global self‐assessment and suggested that the Anamnestic Comparative Self Assessment (ACSA) approach, in which subjects' memories of the best and worst times of their lives are used to anchor a Visual Analog Scale (VAS), provided a serious answer to the serious question, ‘How have you been?’ Bernheim compares and contrasts the ACSA to multi‐item questionnaire QOL instruments, such as the SF‐36, concluding that the ACSA has a number of advantages. His discussion assumes that the use of QOL outcomes in clinical trials is both relevant and appropriate. In the present paper, we document the reasonableness of this latter assumption, ⁴ 4 We emphasize that the choice of the outcome variable in clinical trials has ethical relevance, and that ethical considerations are paramount in choosing length of life and/or quality of life as primary, or at least secondary, outcomes.
contribute to the characterization of the similarities and differences between multi‐item and individualized QOL instruments, and point to some other individualized instruments that may be used in clinical trial contexts. These ‘other individualized instruments’ differ from the ACSA in fundamental ways; but they are individualized in that the subject defines those areas in his/her life that are most important, and these may vary from subject‐to‐subject.     

Dynamic trajectories of volatile and non‐volatile specialised metabolites in ‘overnight’ fragrant flowers of Murraya paniculata

• Ephemeral flowers, especially nocturnal ones, usually emit characteristic scent profiles within their post‐anthesis lifespans of a few hours. Whether these flowers exhibit temporal variability in the composition and profile of volatile and non‐volatile specialised metabolites has received little attention.
• Flowers of Murraya paniculata bloom in the evenings during the summer and monsoon, and their sweet, intense fragrance enhances the plant's value as an ornamental. We aimed to investigate profiles of both volatile and non‐volatile endogenous specialised metabolites (ESM) in nocturnal ephemeral flowers of M. paniculata to examine whether any biochemically diverse groups of ESM follow distinct patterns of accumulation while maintaining synchrony with defensive physiological functions.
• Targeted ESM contents of M. paniculata flowers were profiled at ten time points at 2‐h intervals, starting from late bud stage (afternoon) up to the start of petal senescence (mid‐morning). Emitted volatiles were monitored continuously within the whole 20‐h period using headspace sampling. The ESM contents were mapped by time point to obtain a highly dynamic and biochemically diverse profile. Relative temporal patterns of ESM accumulation indicated that the active fragrance‐emitting period might be divided into ‘early bloom’, ‘mid‐bloom’ and ‘late bloom’ phases. Early and late bloom phases were characterised by high free radical generation, with immediate enhancement of antioxidant enzymes and phenolic compounds. The mid‐bloom phase was relatively stable and dedicated to maximum fragrance emission, with provision for strong terpenoid‐mediated defence against herbivores. The late bloom phase merged into senescence with the start of daylight; however, even the senescent petals continued to emit fragrance to attract diurnal pollinators.
• Our study suggests that dynamic relations between the different ESM groups regulate the short‐term requirements of floral advertisement and phytochemical defence in this ephemeral flower. This study also provided fundamental information on the temporal occurrence of emitted volatiles and internal pools of specialised metabolites in M. paniculata flowers, which could serve as an important model for pollination biology of Rutaceae, which includes many important fruit crops.

     

Identification and characterization of an ecdysiotropic peptide from brain extracts of the gypsy moth,Lymantria dispar

A peptide (Lymantria TE) was isolated from brains of the gypsy moth, Lymantria dispar, which stimulates synthesis of ecdysteroid in the testes of larval and pupal insects. This ecdysiotropic peptide was purified and its structure determined to be NH₂-IIe-Ser-Asp-Phe-Asp-Glu-Tyr-Glu-Pro-Leu-Asn-Asp-Ala-Asp-Asn-Asn-Glu-Val-Leu-Asp-Phe-OH using protein sequence analysis and electrospray mass spectrometry. The peptide was biphasic in activity, with maximal activity in the pupal testes at 10⁻¹³ M and 10⁻⁹ M, with a minimum at 10⁻¹⁰ M, and with maxima at 10⁻¹⁵ M and 10⁻¹⁰ M and minimum at 10⁻¹³ M for larval testes. Arch. Insect Biochem. Physiol. 34:175–189, 1997. © 1997 Wiley-Liss, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.

     

Studies of Asymmetric Styrene Cyclopropanation with a Rhodium(II) Metallopeptide Catalyst Developed with a High‐Throughput Screen

Dirhodium metallopeptides have been developed as selective catalysts for asymmetric cyclopropanation reactions. A selective ligand sequence has been identified by screening on‐bead metallopeptide libraries in a 96‐well plate format. Efficient ligand synthesis and screening allows a 200‐member library to be created and assayed in less than three weeks. These metallopeptides catalyze efficient cyclopropanation of aryldiazoacetates, providing asymmetric access to cyclopropane products in high diastereoselectivity. Chirality 25:493–497, 2013. © 2013 Wiley Periodicals, Inc.     

“Aqua-space®”, a New Headspace Method for Isolation of Natural Floral Aromas Using Humidified Air as a Carrier Gas

A new method called “Aqua-space^®” was developed for the isolation of the natural fragrances of plants. Living flowers were enclosed in a space under simulated natural conditions, and humidified air was pumped into the space as a fragrance carrier. In a comparison among three isolation methods, i.e., Aqua-space^®, headspace, and solvent extraction, the Aqua-space^® method proved to be the most effective in retaining natural fragrances with abundant oxygenated components key to floral fragrances.     

Multi‐functional ion‐sensor based on a photochromic diarylethene with a 1H‐imidazo [4,5‐f][1,10] phenanthroline unit

A new asymmetrical diarylethene containing a 1H‐imidazo [4,5‐f][1,10] phenanthroline unit was synthesized. The compound showed typical photochromism and functioned as a notable fluorescence switch upon alternating irradiation with ultraviolet (UV) and visible light. Its closed‐ring isomer could be used as a selective ‘naked‐eye’ colorimetric sensor for Cu²⁺, accompanied by a notable color change from blue to colorless. Furthermore, the compound was found to be selective towards Ca²⁺, Mg²⁺, and Sr²⁺ with significant fluorescence changes. On the basis of this characteristic, a logic circuit was constructed by utilizing both light and chemical stimuli as inputs and fluorescence intensity at 487 nm as output. Copyright © 2015 John Wiley & Sons, Ltd.     

A novel entecavir analogue constructing with a spiro[2.4]heptane core structure in the aglycon moiety: Its synthesis and evaluation for anti-hepatitis B virus activity

Synthesis of a novel 2′-deoxy-guanine carbocyclic nucleoside 4 constructed with spiro[2.4]heptane core structure in the aglycon moiety was carried out. Radical-mediated 5-exo-dig mode cyclization and following cyclopropanation proceeded efficiently to furnish the spiro alcohol 10. Subsequent Mitsunobu-type glycosylation between 13 and 14, deoxygenation of the 2′-hydroxyl group of 16 and deprotection of 17 gave the title compound 4. Compound 4 demonstrated moderate anti-HBV activity (EC₅₀ value of 0.12 ± 0.02 µM) and no cytotoxicity against HepG2 cells was observed up to 100 µM.     

Redundant Function of cmaA2 and mmaA2 in Mycobacterium tuberculosis cis Cyclopropanation of Oxygenated Mycolates

The Mycobacterium tuberculosis cell envelope contains a wide variety of lipids and glycolipids, including mycolic acids, long-chain branched fatty acids that are decorated by cyclopropane rings. Genetic analysis of the mycolate methyltransferase family has been a powerful approach to assign functions to each of these enzymes but has failed to reveal the origin of cis cyclopropanation of the oxygenated mycolates. Here we examine potential redundancy between mycolic acid methyltransferases by generating and analyzing M. tuberculosis strains lacking mmaA2 and cmaA2, mmaA2 and cmaA1, or mmaA1 alone. M. tuberculosis lacking both cmaA2 and mmaA2 cannot cis cyclopropanate methoxymycolates or ketomycolates, phenotypes not shared by the mmaA2 and cmaA2 single mutants. In contrast, a combined loss of cmaA1 and mmaA2 had no effect on mycolic acid modification compared to results with a loss of mmaA2 alone. Deletion of mmaA1 from M. tuberculosis abolishes trans cyclopropanation without accumulation of trans-unsaturated oxygenated mycolates, placing MmaA1 in the biosynthetic pathway for trans-cyclopropanated oxygenated mycolates before CmaA2. These results define new functions for the mycolic acid methyltransferases of M. tuberculosis and indicate a substantial redundancy of function for MmaA2 and CmaA2, the latter of which can function as both a cis and trans cyclopropane synthase for the oxygenated mycolates.Mycobacterium tuberculosis infection is an ongoing global health crisis. Alleviation of this crisis will require a multidisciplinary approach that must include new antibiotics active against M. tuberculosis. A growing body of literature implicates cell envelope lipids in the pathogenesis of M. tuberculosis infection (5-10, 14-15, 20). The enzymatic pathways that synthesize M. tuberculosis cell envelope lipids are the target of presently available antituberculosis antimicrobials and may be candidates for future antibiotic development.The mycolic acids of M. tuberculosis are alpha-alkyl, beta-hydroxy fatty acids which are 75 to 85 carbons in length (3). There are three classes of major mycolic acids: alpha-, methoxy-, and ketomycolates (Fig. ​(Fig.1).1). Whereas all mycobacteria synthesize mycolic acids, only pathogenic mycobacteria (for example, M. tuberculosis, M. leprae, M. avium, and M. bovis) produce significant quantities of mycolic acids with cyclopropane rings, three-member carbon rings which are added to the meromycolate chain (3). Alpha-mycolates have two cis cyclopropane rings, while methoxy- and ketomycolates have either a cis or trans cyclopropane ring at the proximal position, the latter with a distal methyl branch (Fig. ​(Fig.1).1). In contrast to the case with Escherichia coli, which encodes a single cyclopropane fatty acid synthase (CFAS) (16-17), the M. tuberculosis genome encodes a family of S-adenosyl methionine-dependent methyltransferases that modify cell envelope mycolic acids with methyl branches and cyclopropane rings. Despite substantial amino acid identity, systematic characterization of M. tuberculosis null mutants in each of these methyltransferases has revealed highly specific functions which were not revealed when the enzymes were overexpressed in M. smegmatis (12, 26, 28). Deletion of pcaA greatly reduces synthesis of the proximal cyclopropane ring of the alpha-mycolates (15), whereas deletion of mmaA2 greatly reduces the distal cyclopropane of the same lipid (13). Loss of mmaA2 also causes a mild impairment of methoxymycolate, but not ketomycolate, cis cyclopropanation (13). Similar genetic approaches established cmaA2 as the only trans cyclopropane synthase of oxygenated mycolates (14), while loss of mmaA3 abolishes methoxymycolates, a spontaneous mutation found in many M. bovis BCG strains (4, 11). Finally, deletion of mmaA4 abolishes synthesis of both methoxy- and ketomycolates (10). Recent chemical-genetic analysis of this enzyme family indicates that combined inhibition of their function is lethal to M. tuberculosis, strongly supporting an approach targeting this enzyme family for antimicrobial development (2, 8-19, 25).Open in a separate windowFIG. 1.Chemical structures of the major mycolic acids of M. tuberculosis. Cyclopropane rings and methyl branches are shown and annotated with the methyltransferase responsible for their synthesis.In addition to this essential role in combination, recent evidence implicates individual cyclopropane modifications as important determinants of M. tuberculosis host-pathogen interactions. Inactivation of pcaA causes attenuation of M. tuberculosis in the mouse model of infection while stimulating less-severe granulomatous pathology (15, 23). In contrast, deletion of cmaA2 has no effect on bacterial loads during mouse infection but causes hypervirulence while inducing more-severe granulomatous pathology (24). Inactivation of mmaA4, which leads to an absence of methoxy- and ketomycolates, causes a severe growth defect during the first 3 weeks of infection (10). All of these studies implicate the fine structure of mycolic acids in the pathogenesis of M. tuberculosis infection. One mechanism by which cyclopropanation mediates pathogenesis is through altered inflammatory activity of trehalose dimycolate (TDM), an inflammatory glycolipid. The cyclopropane content of TDM is a major determinant of its inflammatory activity, and this altered TDM is responsible for the virulence phenotypes of cyclopropane-deficient M. tuberculosis strains (9, 23-24).Despite major advances in our understanding of the biosynthesis and pathogenetic function of cyclopropanated mycolic acids through genetic approaches, the methyltransferase(s) that synthesizes the cis cyclopropane ring on the methoxy- and ketomycolates is unknown. In addition, the function of the MmaA1 methyltransferase has not been explored through construction of a null mutant. Prior experiments found that overexpression of mmaA1 in M. tuberculosis resulted in accumulation of trans-unsaturated and -cyclopropanated oxygenated mycolates (27). These data suggested that MmaA1 acts in the biosynthesis of trans-cyclopropanated oxygenated mycolates either by adding the methyl branch distal to the cyclopropane ring or as a cis-trans isomerase or both. In addition, although there was a defect in cis cyclopropanation of methoxymycolates in the ΔmmaA2 strain, this defect was mild, suggesting redundancy with another unidentified enzyme. In this article, we define novel functions for three cyclopropane synthases using a new selectable marker to construct M. tuberculosis strains deficient in multiple mycolic acid methyltransferases. Through this approach, we show that CmaA2 and MmaA2 are redundant for cis cyclopropanation of the proximal position of the methoxymycolates and ketomycolates and that MmaA1 is upstream of CmaA2 in trans cyclopropanation.     

Resolution of 1‐n‐Butyl‐3‐Methyl‐3‐Phospholene 1‐Oxide With TADDOL Derivatives and Calcium Salts of O,O'‐Dibenzoyl‐(2R,3R)‐ or O,O'‐di‐p‐Toluoyl‐(2R,3R)‐tartaric Acid

The resolution methods applying (?)‐(4R,5R)‐4,5‐bis(diphenylhydroxymethyl)‐2,2‐dimethyldioxolane (“TADDOL”), (?)‐(2R,3R)‐α,α,α',α'‐tetraphenyl‐1,4‐dioxaspiro[4.5]decan‐2,3‐dimethanol (“spiro‐TADDOL”), as well as the acidic and neutral Ca²⁺ salts of (?)‐O,O'‐dibenzoyl‐ and (?)‐O,O'‐di‐p‐toluoyl‐(2R,3R)‐tartaric acid were extended for the preparation of 1‐n‐butyl‐3‐methyl‐3‐phospholene 1‐oxide in optically active form. In one case, the intermediate diastereomeric complex could be identified by single‐crystal X‐ray analysis. The absolute P‐configuration of the enantiomers of the phospholene oxide was also determined by comparing the experimentally obtained and calculated CD spectra. Chirality 26:174–182, 2014. © 2014 Wiley Periodicals, Inc.     

Thiacetazone, an antitubercular drug that inhibits cyclopropanation of cell wall mycolic acids in mycobacteria

Background

Mycolic acids are a complex mixture of branched, long-chain fatty acids, representing key components of the highly hydrophobic mycobacterial cell wall. Pathogenic mycobacteria carry mycolic acid sub-types that contain cyclopropane rings. Double bonds at specific sites on mycolic acid precursors are modified by the action of cyclopropane mycolic acid synthases (CMASs). The latter belong to a family of S-adenosyl-methionine-dependent methyl transferases, of which several have been well studied in Mycobacterium tuberculosis, namely, MmaA1 through A4, PcaA and CmaA2. Cyclopropanated mycolic acids are key factors participating in cell envelope permeability, host immunomodulation and persistence of M. tuberculosis. While several antitubercular agents inhibit mycolic acid synthesis, to date, the CMASs have not been shown to be drug targets.

Methodology/Principle Findings

We have employed various complementary approaches to show that the antitubercular drug, thiacetazone (TAC), and its chemical analogues, inhibit mycolic acid cyclopropanation. Dramatic changes in the content and ratio of mycolic acids in the vaccine strain Mycobacterium bovis BCG, as well as in the related pathogenic species Mycobacterium marinum were observed after treatment with the drugs. Combination of thin layer chromatography, mass spectrometry and Nuclear Magnetic Resonance (NMR) analyses of mycolic acids purified from drug-treated mycobacteria showed a significant loss of cyclopropanation in both the α- and oxygenated mycolate sub-types. Additionally, High-Resolution Magic Angle Spinning (HR-MAS) NMR analyses on whole cells was used to detect cell wall-associated mycolates and to quantify the cyclopropanation status of the cell envelope. Further, overexpression of cmaA2, mmaA2 or pcaA in mycobacteria partially reversed the effects of TAC and its analogue on mycolic acid cyclopropanation, suggesting that the drugs act directly on CMASs.

Conclusions/Significance

This is a first report on the mechanism of action of TAC, demonstrating the CMASs as its cellular targets in mycobacteria. The implications of this study may be important for the design of alternative strategies for tuberculosis treatment.     

Carbon isotope ratios of photolithotrophs from allt meall nan damh,a burn at ardeonaig,Perthshire, and their ecophysiological significance

Summary

δ¹³C measurements were made of dissolved inorganic C, and of submerged benthic cyanobacteria, algae and bryophytes, from Allt Meall nan Damh, a burn at Ardeonaig, Perthshire. The δ¹³C of the CO₂, HCO3/- and CO3/2- components of the inorganic C were computed, and the Δ values of the organic C in the photolithotrophs were then calculated relative to dissolved CO₂. The decreasing order of A values in the Ardeonaig Burn is Lemanea and bryophytes ≥ green macroalgae and Audouinella > diatom mats, which is the same as in the Dighty Burn. However, the Δ values of Lemanea and the bryophytes, which depend on diffusive CO₂ entry, are lower at Ardeonaig than in the Dighty Burn, suggesting greater diffusive limitation to photosynthesis in the Ardeonaig Burn. It is not easy to relate this difference in Δ values in Lemanea to the higher C:N atomic ratio in the Ardeonaig Burn (21.2 ± 0.64) than in the Dighty Burn (9.5–11.0). The Δ values relative to HCO3/- for the HCO3/--using diatom mat in the Ardeonaig Burn is also lower than that in the Dighty Burn; this is consistent with a greater diffusion limitation of photosynthesis in the thicker mats in the Ardeonaig Burn. The δ¹³C of a Lyngbya mat overlying a Lemanea population stranded by low summer water levels indicates that some of the C fixed by the HCO3/--using Lyngbya comes from respiration of low-δ¹³C inorganic C by the Lemanea which is shaded by the Lyngbya. The δ¹³C values of Mesotaenium in its mucilage sheath on a thinly vegetated bank is suggestive of predominant use of the higher CO₂ concentrations with lower δ¹³C from groundwater rather than of atmospheric CO₂ yielding lower dissolved CO₂ concentrations with a higher δ¹³C value.     

Computational chemical analysis of Ru(II)‐Pheox–catalyzed highly enantioselective intramolecular cyclopropanation reactions

Computational chemical analysis of Ru(II)‐Pheox–catalyzed highly enantioselective intramolecular cyclopropanation reactions was performed using density functional theory (DFT). In this study, cyclopropane ring–fused γ‐lactones, which are 5.8 kcal/mol more stable than the corresponding minor enantiomer, are obtained as the major product. The results of the calculations suggest that the enantioselectivity of the Ru(II)‐Pheox–catalyzed intramolecular cyclopropanation reaction is affected by the energy differences between the starting structures 5l and 5i . The reaction pathway was found to be a stepwise mechanism that proceeds through the formation of a metallacyclobutane intermediate. This is the first example of a computational chemical analysis of enantioselective control in an intramolecular carbene‐transfer reaction using C₁‐symmetric catalysts.     

Efficacy of biorational insecticides against chilli thrips,Scirtothrips dorsalis (Thysanoptera: Thripidae), infesting roses under nursery conditions

We evaluated biopesticides based on entomopathogenic fungi, azadirachtin and horticultural oils for the management of the chilli thrips, Scirtothrips dorsalis Hood, an economically significant invasive pest in the United States. Insecticides were applied four times at 7‐ to 10‐day intervals against established S. dorsalis infestations on shrub roses KnockOut^®, Rosa x ‘Radrazz’ under simulated nursery conditions. When applied as stand‐alone treatments, Beauveria bassiana GHA (BotaniGard^® ES), Metarhizium brunneum F52 (Met‐52 EC), a horticultural oil (SuffOil‐X^®) and azadirachtin (Molt‐X^®) at label rates provided significant control, reducing populations of S. dorsalis by 48–71% compared with control over 4–6 weeks. Similar results were observed when the biopesticides were applied in rotation with each other. A conventional standard, spinosad (Conserve^® SC), was consistently the most effective treatment in these studies, reducing thrips populations by >95% overall. In another study, more effective control (87%–92%) was achieved in biopesticide rotation programmes that included spinosad, when compared with those that did not. Results also showed that these biopesticides can be tank‐mixed. However, there was no evidence that B. bassiana or M. brunneum combined with azadirachtin resulted in additive or synergistic control, as neither tank‐mix treatment improved control compared with azadirachtin alone. These findings highlight the potential use of biopesticides in rotation programmes with conventional insecticides to manage S. dorsalis on roses. Biopesticides evaluated in this study can be incorporated into an IPM programme for roses.