Real-Time Monitoring of (E)-β-Farnesene Emission in Colonies of the Pea Aphid, Acyrthosiphon pisum, Under Lacewing and Ladybird Predation

Aphids (Homoptera) are constantly under attack by a variety of predators and parasitoids. Upon attack, most aphids release alarm pheromone that induces escape behavior in other colony members, such as dropping off the host plant. In the pea aphid, Acyrthosiphon pisum Harris (Aphididae), the only component of this alarm pheromone is the sesquiterpene (E)-β-farnesene (EBF). EBF is thought to act as a kairomone by attracting various species of parasitoids and predators including lacewings and ladybirds. Lately, it also was proposed that EBF is constantly emitted in low quantities and used by aphids as a social cue. No study has focused on emission dynamics of this compound over a long time period. Here, we present the first long-time monitoring of EBF emission in aphid colonies using real-time monitoring. We used a zNose^TM to analyze the headspace of colonies of the pea aphid, under lacewing (Neuroptera: Chrysopidae) and ladybird (Coleoptera: Coccinellidae) predation, over 24 hr. We found no emission of EBF in the absence of predation. When either a ladybird adult or a lacewing larva was placed in an aphid colony, EBF was detected in the headspace of the colonies in the form of emission blocks; i.e., periods in which EBF was emitted alternating with periods without EBF emission. The number of emission blocks correlated well with the number of predation events that were determined at the end of each experiment. There was no circadian rhythm in alarm pheromone emission, and both predators were active during both night and day. Our results show that alarm pheromone emission pattern within an aphid colony is driven by the feeding behavior of a predator.     

Plant–Plant Signaling: Ethylene Synergizes Volatile Emission In Zea mays Induced by Exposure to (Z)-3-Hexen-1-ol

Leaf alcohol (Z)-3-hexen-1-ol (Z-3-ol) is emitted by green plants upon mechanical damage. Exposure of intact maize plants to Z-3-ol induces the emission of a volatile blend that is typically released after caterpillar feeding and attracts natural enemies of the herbivores [herbivore-induced volatile organic compounds (HI-VOC)]. Thus, it has been suggested that Z-3-ol might have a function in indirect plant defense mediating plant–plant signaling and intraplant information transfer. Here, we demonstrate that HI-VOC induction by Z-3-ol is synergized by the phytohormone ethylene. Exposure to Z-3-ol at doses of 100 and 250 nmol induced HI-VOC emission in intact maize plants. HI-VOC emissions increased by 2.5-fold when ethylene was added. The effect of ethylene was more pronounced (5.1- to 6.6-fold) when only total sesquiterpene release was considered. In contrast, ethylene alone had no inductive effect but rather decreased the emission of the constitutive maize volatile linalool. We suggest that ethylene plays a synergistic role in plant–plant signaling mediated by green leaf volatiles.     

Apple Fruit Infested with Codling Moth are More Attractive to Neonate Codling Moth Larvae and Possess Increased Amounts of (E,E)-α-Farnesene

Apple fruit artificially infested with codling moth larvae attracted significantly more neonate larvae of the codling moth, Cydia pomonella than uninfested fruit. A greater number of larvae responded to odor in an olfactometer from codling moth-infested cold-stored Red Delicious thinning apples than uninfested apples. Immature Granny Smith, Red Delicious, or Golden Delicious apples that were infested on the tree for five days by codling moth larvae were more attractive to neonate codling moth larvae than similar but uninfested fruit of the same varieties. Apples infested on the tree and sampled five days later also contained significantly greater amounts of the larval attractant (E,E)--farnesene, compared to uninfested apples. Other types of injury to apple fruit did not produce results similar to that from codling moth infestation, either in increased attractiveness to codling moth larvae or in increased quantities of (E,E)--farnesene. These results are consistent with the reported attractiveness of (E,E)--farnesene to neonate codling moth larvae.     

A new method for the synthesis of tetrahydrothiophene-S,S-dioxide derivatives: the Michael ring closure reaction between halomethyl (E)-β-styryl sulfones and CH-acids

Bromomethyl and chloromethyl (E)-β-styryl sulfones enter a Michael ring closure reaction with sodium enolates prepared from dimethyl malonate, malononitrile and ethyl acetoacetate. The condensation results in formation of substituted tetrahydrothiophene-S,S-dioxides. It is a new instance of α-haloalkyl sulfones transformations, which are not connected with Ramberg–Bäcklund reaction.     

Discrepancy Between Antennal and Behavioral Responses for Enantiomers of α-Pinene: Electrophysiology and Behavior of Helicoverpa armigera (Lepidoptera)

The ability of adult cotton bollworm, Helicoverpa armigera (Hübner), to distinguish and respond to enantiomers of alpha-pinene was investigated with electrophysiological and behavioral methods. Electroantennogram recordings using mixtures of the enantiomers at saturating dose levels, and single unit electrophysiology, indicated that the two forms were detected by the same receptor neurons. The relative size of the electroantennogram response was higher for the (-) compared to the (+) form, indicating greater affinity for the (-) form at the level of the dendrites. Behavioral assays investigated the ability of moths to discriminate between, and respond to the (+) and (-) forms of alpha-pinene. Moths with no odor conditioning showed an innate preference for (+)-alpha-pinene. This preference displayed by naive moths was not significantly different from the preferences of moths conditioned on (+)-alpha-pinene. However, we found a significant difference in preference between moths conditioned on the (-) enantiomer compared to naive moths and moths conditioned on (+)-alpha-pinene, showing that learning plays an important role in the behavioral response. Moths are less able to distinguish between enantiomers of alpha-pinene than different odors (e.g., phenylacetaldehyde versus (-)-alpha-pinene) in learning experiments. The relevance of receptor discrimination of enantiomers and learning ability of the moths in host plant choice is discussed.     

Initial use of 1,1′-oxalyldiimidazole for inorganic synthesis: Decomposition of the ligand as a means to the preparation of an imidazole- and oxalate(-2)-containing, 1D copper(II) complex

The use of 1,1′-oxalyldiimidazole, (im)COCO(im), for the synthesis of coordination complexes is explored for the first time. The [Cu₂(O₂CMe)₄(H₂O)₂]/(im)COCO(im) reaction system in 96% EtOH yields the new, 1D coordination polymer [Cu(ox)(Him)₂]_n (1), where Him is the neutral imidazole and ox^2? is the oxalate(-2) ligand. A mechanism for the hydrolytic decomposition of the ligand is proposed. Complex 1 comprises neutral, zigzag chains with the η¹:η¹:η¹:η¹:μ (2.1111 using Harris notation) ox^2? ligand bridging two neighboring Cu^II centers; two cis Him groups complete a Jahn–Teller distorted octahedral geometry at the metal. The dc, variable-temperature magnetic susceptibility data for the complex reveal antiferromagnetic Cu^II?Cu^II exchange interactions.     

Coevolution of the Activity and Thermostability of an ϵ-Keto Ester Reductase for Better Synthesis of an (R)-α-Lipoic Acid Precursor

In this work, we have identified a significantly improved variant (S131Y/Q252I) of the natural ϵ-keto ester reductase CpAR2 from Candida parapsilosis for efficiently manufacturing (R)-8-chloro-6-hydroxyoctanoic acid [(R)-ECHO] through co-evolution of activity and thermostability. The activity of the variant CpAR2_S131Y/Q252I towards the ϵ-keto ester ethyl 8-chloro-6-oxooctanoate was improved to 214 U mg⁻¹—from 120 U mg⁻¹ in the case of the wild-type enzyme (CpAR2_WT)—and the half-deactivating temperature (T₅₀, for 15 min incubation) was simultaneously increased by 2.3 °C in relation to that of CpAR2_WT. Consequently, only 2 g L⁻¹ of lyophilized E. coli cells harboring CpAR2_S131Y/Q252I and a glucose dehydrogenase (GDH) were required in order to achieve productivity similar to that obtained in our previous work, under optimized reaction conditions (530 g L⁻¹ d⁻¹). This result demonstrated a more economical and efficient process for the production of the key (R)-α-lipoic acid intermediate ethyl 8-chloro-6-oxooctanoate.     

Cyanoethylation of cyclopentadiene: Isolation of penta- and hexa(β-cyanoethyl)cyclopentadiene and an unexpected acrylonitrile polymer

Summary The cyanoethylation of cyclopentadiene was examined under a variety of reaction conditions. Approximately 9% of cyclopentadiene was converted to the desired hexa(-cyanoethyl)cyclopentadiene when the amount of acrylonitrile to cyclopentadiene was increased from 2 to 7 equivalents under phase transfer conditions. The low conversion is due to competitive formation of various unreactive side-products. For example, termination leading to less-highly substituted products was confirmed by isolation of crystalline 1,1,2,3,4-penta(-cyanoethyl)cyclopentadiene. Another side product isolated and characterized by ¹³C NMR was an oligomer of acrylonitrile attached to hexa(-cyanoethyl)cyclopentadiene; the anion (at a -alkyl position) of the latter apparently acted as anionic initiator. Attempts to induce thermal polymerization and cyclotrimerization of the pendent cyano groups of hexa(-cyanoethyl)cyclopentadiene were unsuccessful even with added Lewis acid catalysts. Reduction to the hexaamine was only partially successful.     

β-Ketoacyl-acyl Carrier Protein Synthase I (KASI) Plays Crucial Roles in the Plant Growth and Fatty Acids Synthesis in Tobacco

Fatty acids serve many functions in plants, but the effects of some key genes involved in fatty acids biosynthesis on plants growth and development are not well understood yet. To understand the functions of 3-ketoacyl-acyl-carrier protein synthase I (KASI) in tobacco, we isolated two KASI homologs, which we have designated NtKASI-1 and NtKASI-2. Expression analysis showed that these two KASI genes were transcribed constitutively in all tissues examined. Over-expression of NtKASI-1 in tobacco changed the fatty acid content in leaves, whereas over-expressed lines of NtKASI-2 exhibited distinct phenotypic features such as slightly variegated leaves and reduction of the fatty acid content in leaves, similar to the silencing plants of NtKASI-1 gene. Interestingly, the silencing of NtKASI-2 gene had no discernibly altered phenotypes compared to wild type. The double silencing plants of these two genes enhanced the phenotypic changes during vegetative and reproductive growth compared to wild type. These results uncovered that these two KASI genes had the partially functional redundancy, and that the KASI genes played a key role in regulating fatty acids synthesis and in mediating plant growth and development in tobacco.     

Astragalus membranaceus Inhibits Peritoneal Fibrosis via Monocyte Chemoattractant Protein (MCP)-1 and the Transforming Growth Factor-β1 (TGF-β1) Pathway in Rats Submitted to Peritoneal Dialysis

Inflammation and transforming growth factor-β1 (TGF-β1) contribute to the development of peritoneal fibrosis (PF), which is associated with peritoneal dialysis (PD). Astragalus membranaceus (Astragalus) has anti-inflammatory and anti-fibrotic effects in many diseases. The goal of this study was to determine the anti-fibrotic effects of Astragalus on the PF response to PD. A rat model of PD was induced using standard PD fluid, and PF was verified by HE and Masson’s staining, as well as through the expression of fibroblast surface protein (FSP) and collagen III. The expression levels of monocyte chemoattractant protein (MCP)-1, F4/80 (macrophage/monocyte marker in rat), TGF-β1 and the downstream proteins phospho-SMAD 2/3 in dialyzed peritoneal tissue treated with or without Astragalus was evaluated using immunohistochemistry analysis. Overall correlations between MCP-1 and TGF-β1 staining were analyzed using both the Spearman and Pearson methods. The results showed that Astragalus could inhibit the recruitment and activation of monocytes/macrophages, thereby reducing the production of TGF-β1 in the dialyzed peritoneal membrane. PF was also significantly decreased following treatment with Astragalus. MCP-1 expression had a strong positive correlation with TGF-β1 sensitivity, suggesting that the anti-fibrotic function of Astragalus was mediated by MCP-1 and the TGF-β1 pathway. Our results indicate that Astragalus could be a useful agent against PD-induced PF.     

Use of Linear Free Energy Relationships (LFERs) to Elucidate the Mechanisms of Reaction of a γ-Methyl-β-alkynyl and an ortho-Substituted Aryl Chloroformate Ester

The specific rates of solvolysis of 2-butyn-1-yl-chloroformate (1) and 2-methoxyphenyl chloroformate (2) are studied at 25.0 °C in a series of binary aqueousorganic mixtures. The rates of reaction obtained are then analyzed using the extended Grunwald-Winstein (G-W) equation and the results are compared to previously published G-W analyses for phenyl chloroformate (3), propargyl chloroformate (4), p-methoxyphenyl choroformate (5), and p-nitrophenyl chloroformate (6). For 1, the results indicate that dual side-by-side addition-elimination and ionization pathways are occurring in some highly ionizing solvents due to the presence of the electron-donating γ-methyl group. For 2, the analyses indicate that the dominant mechanism is a bimolecular one where the formation of a tetrahedral intermediate is rate-determining.     

Reaction Pathways for the Enzymatic Degradation of Poly(Ethylene Terephthalate): What Characterizes an Efficient PET-Hydrolase?

Bioprocessing of polyester waste has emerged as a promising tool in the quest for a cyclic plastic economy. One key step is the enzymatic breakdown of the polymer, and this entails a complicated pathway with substrates, intermediates, and products of variable size and solubility. We have elucidated this pathway for poly(ethylene terephthalate) (PET) and four enzymes. Specifically, we combined different kinetic measurements and a novel stochastic model and found that the ability to hydrolyze internal bonds in the polymer (endo-lytic activity) was a key parameter for overall enzyme performance. Endo-lytic activity promoted the release of soluble PET fragments with two or three aromatic rings, which, in turn, were broken down with remarkable efficiency (k_cat/K_M values of about 10⁵ M⁻¹s⁻¹) in the aqueous bulk. This meant that approximatly 70 % of the final, monoaromatic products were formed via soluble di- or tri-aromatic intermediates.     

Enantioselective Cascade Biocatalysis for Deracemization of Racemic β-Amino Alcohols to Enantiopure (S)-β-Amino Alcohols by Employing Cyclohexylamine Oxidase and ω-Transaminase

Optically active β-amino alcohols are very useful chiral intermediates frequently used in the preparation of pharmaceutically active substances. Here, a novel cyclohexylamine oxidase (ArCHAO) was identified from the genome sequence of Arthrobacter sp. TYUT010-15 with the R-stereoselective deamination activity of β-amino alcohol. ArCHAO was cloned and successfully expressed in E. coli BL21, purified and characterized. Substrate-specific analysis revealed that ArCHAO has high activity (4.15 to 6.34 U mg⁻¹ protein) and excellent enantioselectivity toward the tested β-amino alcohols. By using purified ArCHAO, a wide range of racemic β-amino alcohols were resolved, (S)-β-amino alcohols were obtained in >99 % ee. Deracemization of racemic β-amino alcohols was conducted by ArCHAO-catalyzed enantioselective deamination and transaminase-catalyzed enantioselective amination to afford (S)-β-amino alcohols in excellent conversion (78–94 %) and enantiomeric excess (>99 %). Preparative-scale deracemization was carried out with 50 mM (6.859 g L⁻¹) racemic 2-amino-2-phenylethanol, (S)-2-amino-2-phenylethanol was obtained in 75 % isolated yield and >99 % ee.     

6,6′‐Bis(5,5,8,8‐tetramethyl‐5,6,7,8‐tetrahydro‐benzo[1,2,4]triazin‐3‐yl) [2,2′]bipyridine,an Effective Extracting Agent for the Separation of Americium(III) and Curium(III) from the Lanthanides

Abstract

The extraction of americium(III), curium(III), and the lanthanides(III) from nitric acid by 6,6′‐bis(5,5,8,8‐tetramethyl‐5,6,7,8‐tetrahydro‐benzo[1,2,4]triazin‐3‐yl)‐[2,2′]bipyridine (CyMe₄‐BTBP) has been studied. Since the extraction kinetics were slow, N,N′‐dimethyl‐N,N′‐dioctyl‐2‐(2‐hexyloxy‐ethyl)malonamide (DMDOHEMA) was added as a phase transfer reagent. With a mixture of 0.01 M CyMe₄‐BTBP+0.25 M DMDOHEMA in n‐octanol, extraction equilibrium was reached within 5 min of mixing. At a nitric acid concentration of 1 M, an americium(III) distribution ratio of approx. 10 was achieved. Americium(III)/lanthanide(III) separation factors between 50 (dysprosium) and 1500 (lanthanum) were obtained. Whereas americium(III) and curium(III) were extracted as disolvates, the stoichiometries of the lanthanide(III) complexes were not identified unambiguously, owing to the presence of DMDOHEMA. In the absence of DMDOHEMA, both americium(III) and europium(III) were extracted as disolvates. Back‐extraction with 0.1 M nitric acid was thermodynamically possible but rather slow. Using a buffered glycolate solution of pH=4, an americium(III) distribution ratio of 0.01 was obtained within 5 min of mixing. There was no evidence of degradation of the extractant, for example, the extraction performance of CyMe₄‐BTBP during hydrolylsis with 1 M nitric acid did not change over a two month contact.     

Enhancement of scaffolding properties for poly(3-hydroxybutyrate): blending with poly-β-alanine and wet electrospinning

Poly-β-alanine (PBA), and its derivatives poly(α-methyl-β-alanine) and poly[N-(3-methoxypropyl-β-alanine) were synthesized by hydrogen transfer polymerization (HTP). Porous 3?D matrices of poly(3-hydroxybutyrate) (P3HB) reinforced with PBA/its derivatives were obtained via lyophilization and wet electrospinning. However, mechanical properties of the porous matrices prepared by wet electrospinning were found to present superior performance for tissue engineering applications. Cell culture study was performed by using wet electrospun P3HB matrices doped with 10% (w/w) PBA which show better manipulation ability, chemical and mechanical properties. Scaffolds of P3HB-PBA (10% w/w) blend was determined to demonstrate better cell attachment and proliferation compared to the scaffolds of pure P3HB.     

Unusual interaction extended between the pyranose ring oxygen and Zn(II) center in the complexes derived from 4,6-O-butylidene/ethylidene-N-(α-hydroxynaphthylidene/o-hydroxybenzylidene)-β-d-glucopyranosylamine: Evidence for a pseudo-bicapped tetrahedral complex of Zn(II) based on the crystal structure

The Zn(II) complexes of 4,6-O-butylidene/ethylidene-N-(α-hydroxynaphthylidene/o-hydroxybenzylidene)-β-d-glucopyranosylamine have been synthesized and characterized using spectral and analytical methods and structure for one of the products was established. The geometry of the complexes vary from unusual distorted trigonal bipyramidal to pseudo-bicapped tetrahedron depending upon the extent of binding of pyranose ring oxygens to the Zn(II) ion, as evidenced from crystal structures. Such interaction is also reflected on the optical rotation and CD spectral properties of these complexes in solution.