High-resolution nuclear magnetic resonance spectroscopy studies of polysaccharides crosslinked by sodium trimetaphosphate: a proposal for the reaction mechanism

An NMR spectroscopy study ((31)P, (1)H, (13)C) of the postulated crosslinking mechanism of sodium trimetaphosphate (STMP) on polysaccharides is reported using methyl alpha-D-glucopyranoside as a model. In a first step, reaction of STMP with Glc-OMe gives grafted sodium tripolyphosphate (STPP(g)). On the one hand, STTP(g) can react with a second alcohol functionality to give a crosslinked monophosphate. On the other hand, a monophosphate (grafted phosphate) could be obtained by alkaline degradation of STPP(g). NMR spectroscopy allows to detect the various species formed and to obtain the crosslinking density of STMP-polysaccharides hydrogels.     

Identification of a novel bifunctional delta12/delta15 fatty acid desaturase from a basidiomycete, Coprinus cinereus TD#822-2

A new gene encoding a delta12 fatty acid desaturase-related protein was cloned from a multicellular basidiomycete Coprinus cinereus TD#822-2. The 1326 bp full-length gene, designated as Cop-odeA, codes for a putative protein of 442 amino acids with a MW of 49224. The Cop-odeA yeast transformant accumulated four new fatty acids identified as 9,12-hexadecadienoic acid, 9,12,15-hexadecatrienoic acid, linoleic acid, and alpha-linolenic acid, which comprised 8.8%, 1.0%, 29.0%, and 0.6% of the total fatty acids, respectively. The Cop-odeA protein was confirmed to be a novel bifunctional fatty acid desaturase with both high delta12 desaturase activity and unusual delta15 desaturase activity.     

Single and cell population respiratory oscillations in yeast: a 2-photon scanning laser microscopy study

Two-photon scanning laser and confocal microscopies were used to image metabolic dynamics of single or cell populations of Saccharomyces cerevisiae strain 28033. Autofluorescence of reduced nicotinamide nucleotides, and mitochondrial membrane potential (DeltaPsim), were simultaneously monitored. Spontaneous, large-scale synchronized oscillations of NAD(P)H and DeltaPsim throughout the entire population of yeasts occurred under perfusion with aerated buffer in a continuous single-layered film of organisms. These oscillations stopped in the absence of perfusion and the intracellular NAD(P)H pool became reduced. Individual mitochondria within a single yeast also showed in-phase synchronous responses with the cell population, in both tetramethylrhodamine ethyl ester (or tetramethylrhodamine methyl ester) and autofluorescence. A single, localized, laser flash also triggered mitochondrial oscillations in single cells suggesting that the mitochondrion may behave as an autonomous oscillator. We conclude that spontaneous oscillations of S. cerevisiae mitochondrial redox states and DeltaPsim occur within individual yeasts, and synchrony of populations of organisms indicates the operation of an efficient system of cell-cell interaction to produce concerted metabolic multicellular behaviour on the minute time scale in both cases.     

Synthesis and Structure-Activity Relationship of [Nle10]Neurokinin A (4–10) Analogs with Constraint in the Backbone and at Position Six

Steric requirements of binding [Nle¹⁰]NKA(4–10) to NK-2 receptor were studied by introducing conformationally constrained amino acid analogs into its sequence. Two series of [Nle¹⁰]NKA(4–10) analogs were synthesized to investigate (i) the significance of a putative β-turn in the receptor-ligand interaction by insertion of either (S)- or (R)-Gly⁸{ANC-2}Leu⁹ γ-lactams to mimic a β-turn constraint, and (ii) the effect of hindered rotation in the Φ, χ¹ and χ² dihedral angle space of the crucially important Phe⁶ which was replaced systematically with d-Phe, d- and l-Tyr, as well as with their conformationally constrained analogs, Tic, HOTic and β-MePhe. Competition binding experiments with [³H]NKA were performed using cloned human NK-2 receptors expressed in CHO cells. The analog possessing only an (R)-Gly⁸{ANC-2}Leu⁹ constraint, had the same binding affinity as that of the parent peptide. The rank order of potency of the other analogs showed a cumulative effect of different structural modifications in decreasing the binding affinity, i.e., when changing the configuration of the lactam ring to S, replacing Phe⁶ with constrained analogs, Tic or β-MePhe, changing the configuration of the amino acid at position six to d, and introducing a hydroxyl group on the aromatic ring. Ferenc ?tv?s and Dmitry S. Gembitsky - Made an equal contribution. Abbreviations used for amino acids and peptides follow the recommendations of the IUPAC-IUB Commission of Biochemical Nomenclature, Eur. J. Biochem. (1984) 138, 9–37     

Associative learning in immature lacewings (Ceraeochrysa cubana)

It is known that many social insects and arthropod predators and parasitoids can learn the association between a resource and volatile cues. Although there are various studies on the effect of experience in immature arthropods on behavior later in adult life, not much is known about the effects of such experiences on immature behavior. This was investigated here in the lacewing Ceraeochrysa cubana (Hagen) (Neuroptera: Chrysopidae). Whereas adults of this lacewing feed on plant‐provided food and honeydew, larvae are voracious polyphagous predators of several insect pests, and therefore important for biological control. Hence, studying the foraging behavior and the effects of learning in immatures of this species is important. We exposed immatures to the volatile methyl salicylate (MeSA), which was either associated with food or with the absence of food. Subsequently, their response to this volatile was tested in an olfactometer. Immatures that had experienced the association of MeSA with food were attracted to it and immatures that were exposed to MeSA during food deprivation were repelled. Subsequently, predator immatures that had experienced the association between MeSA and food were released on a plant without food and were found to use this volatile in locating patches with food. In contrast, larvae without such experience were found equally on food patches with and without the volatile. We conclude that these immature predators are capable of learning the association between volatiles and food, or the absence of food, and use this during foraging.     

Exploring antidiabetic potential of adamantyl-thiosemicarbazones via aldose reductase (ALR2) inhibition

The role of aldose reductase (ALR2) in diabetes mellitus is well-established. Our interest in finding ALR2 inhibitors led us to explore the inhibitory potential of new thiosemicarbazones. In this study, we have synthesized adamantyl-thiosemicarbazones and screened them as aldehyde reductase (ALR1) and aldose reductase (ALR2) inhibitors. The compounds bearing phenyl 3a, 2-methylphenyl 3g and 2,6-dimethylphenyl 3m have been identified as most potent ALR2 inhibitors with IC₅₀ values of 3.99 ± 0.38, 3.55 ± 0.26 and 1.37 ± 0.92 µM, respectively, compared with sorbinil (IC₅₀ = 3.14 ± 0.02 μM). The compounds 3a, 3g, and 3m also inhibit ALR1 with IC₅₀ value of 7.75 ± 0.28, 7.26 ± 0.39 and 7.04 ± 2.23 µM, respectively. Molecular docking was also performed for putative binding of potent inhibitors with target enzyme ALR2. The most potent 2,6-dimethylphenyl bearing thiosemicarbazone 3m (IC₅₀ = 1.37 ± 0.92 µM for ALR2) and other two compound 3a and 3g could potentially lead for the development of new therapeutic agents.     

Masculinization of the gynogenetic juvenile ship sturgeon (Acipenser nudiventris Lovetsky, 1828) using 17α‐methyl testosterone

In sturgeons, the induction of gynogenesis and sex reversal could be important for potential production of neomale sturgeon and all‐female progeny for caviar production. The aim of this study was sex reversal of ship sturgeon (Acipenser nudiventris Lovetsky, 1828) gynogen into male sex. Five‐month‐old gynogens were sex reversed into male by including 17α‐methyl testosterone in their food for 7 months. Three treatments were considered as follows: (a) without treated (gynogen control), (b) 10 mg MT/kg diet, and (c) 50 mg MT/kg diet. All treatments (60 individuals) were sampled both the 30 and 36 months old and their sex was determined using classical histology method of gonad. The sex ratio of the progenies in the gynogen control were 73.3% female and 26.7% male. In treatment of 10 mg MT/kg feed, 18 specimens were studied that half of them (50%) showed pseudo‐testicular structure in the female gonad. That is 50% of the specimens were intersex, 27.7% were male and 22.3% were female. All of the fish fed by 50 mg MT/kg feed had been sex reversed to male. Sexual maturation of these fish had been recognized in stage III at 36 months old. In conclusion, 50 mg MT/kg feed found as effective dose for successful sex reversal in gynogenetic ship sturgeon.     

Production of fuels and chemicals from renewable resources using engineered Escherichia coli

Biotechnological production of fuels and chemicals from renewable resources is an appealing way to move from the current petroleum-based economy to a biomass-based green economy. Recently, the feedstocks that can be used for bioconversion or fermentation have been expanded to plant biomass, microbial biomass, and industrial waste. Several microbes have been engineered to produce chemicals from renewable resources, among which Escherichia coli is one of the best studied. Much effort has been made to engineer E. coli to produce fuels and chemicals from different renewable resources. In this paper, we focused on E. coli and systematically reviewed a range of fuels and chemicals that can be produced from renewable resources by engineered E. coli. Moreover, we proposed how can we further improve the efficiency for utilizing renewable resources by engineered E. coli, and how can we engineer E. coli for utilizing alternative renewable feedstocks. e.g. C1 gases and methanol. This review will help the readers better understand the current progress in this field and provide insights for further metabolic engineering efforts in E. coli.     

Biochemical insights into basal and induced resistance in cabbage to black rot

Black rot, caused by Xanthomonas campestris pv. campestris (Xcc), is the most devastating disease of brassica, but the mechanisms of basal or induced resistance in cabbage remain largely unknown. Here, we performed three experiments to investigate biochemical features associated with cabbage resistance to black rot. In the first experiment, biochemical changes were assessed in plants that were inoculated with a highly (UFPR 5) or a moderately (Xcc 10) aggressive Xcc isolate. In the second experiment, we examined the biochemical responses in two cultivars (Chato de Quintal [CQ] and Louco de Verão [LV], susceptible and moderately resistant to Xcc, respectively). Finally, we examined whether acibenzolar‐S‐methyl (ASM) could induce cabbage resistance to Xcc. Plants inoculated with the Xcc 10 isolate displayed higher activities of superoxide dismutase (SOD), peroxidase (POX) and ascorbate peroxidase (APX), whereas activities of chitinase (CHI), β‐1,3‐glucanase (GLU) and polyphenol oxidase (PPO) as well as the concentrations of hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) were lower compared to plants inoculated with the UFPR 5 isolate. The resistance of the cultivar LV to Xcc was linked to increases in the activities of CHI, GLU, and PPO and decreases in the activities of SOD, POX and APX as well as in the concentrations of H₂O₂ and MDA relative to the cultivar CQ. In general, ASM‐sprayed plants displayed higher activities for the enzymes studied, which was associated with decreased disease symptoms and oxidative stress. Taken together, our results demonstrated that high activities of both defence and antioxidant enzymes played a major role in both basal and induced resistance of cabbage to black rot.