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Proline
Terms modified by Proline Selected AbstractsAdvances towards Highly Active and Stereoselective Simple and Cheap Proline-Based Organocatalysts,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 29 2010Francesco Giacalone Abstract Ten 4-acyloxy- L -prolines were screened as catalysts at loadings of 2,0.1 mol-% for the direct asymmetric aldol reaction in water by using variable amounts of water. Among them, a new catalyst, the L -proline carrying a trans -4-(2,2-diphenylacetoxy) group, and a catalyst previously synthesized by us, the L -proline carrying a trans -4-(4-phenylbutanoyloxy) group, were found to be excellent catalysts for the aldol reaction between cyclohexanone or cyclopentanone and substituted benzaldehydes when employed in only 1 and 0.5 mol-%,respectively, at room temperature without additives. For such catalysts, high turnover numbers were obtained, which are among the highest values obtained for enamine organocatalysis. Finally, these catalysts can be synthesized by direct O -acylation from inexpensive molecules and successfully used in scaled-up reactions. [source] Enhanced Activity and Stereoselectivity of Polystyrene-Supported Proline-Based Organic Catalysts for Direct Asymmetric Aldol Reaction in WaterEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 31 2009Michelangelo Gruttadauria Abstract Several polystyrene-supported proline dipeptides and a prolinamide derivative were prepared by thiol,ene coupling. These materials were used as catalysts for the direct asymmetric aldol reaction in water, and results compared with unsupported catalysts in water. Such an approach gave more active or stereoselective catalysts compared to the unsupported compounds, showing that our immobilization procedure may be useful to develop catalytic materials with enhanced performance. Moreover, these catalysts can be recovered and reused for at least nine times without loss of activity or can be easily regenerated when their activity has decreased. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Hydrophobically Directed Aldol Reactions: Polystyrene-Supported L -Proline as a Recyclable Catalyst for Direct Asymmetric Aldol Reactions in the Presence of Water,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 28 2007Michelangelo Gruttadauria Abstract A simple synthetic methodology for the preparation of a polystyrene-supported L -proline material is reported, and this material has been used as catalyst in direct asymmetric aldol reactions between several ketones and arylaldehydes to furnish aldol products in high yields and stereoselectivities. Screening of solvents showed that these reactions take place only in the presence of water or methanol, at lower levels of conversion in the latter case. This solvent effect, coupled with the observed high stereoselectivities, has been explained in terms of the formation of a hydrophobic core in the inner surface of the resin, whereas the hydrophilic proline moiety lies at the resin/water interface. Such a microenvironment both promotes the aldol reaction and increases the stereoselectivity. Recycling investigations have shown that this material can be reused, without loss in levels of conversion and stereoselectivity, for at least five cycles. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Sensory aroma from Maillard reaction of individual and combinations of amino acids with glucose in acidic conditionsINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 9 2008Kam Huey Wong Summary The aroma produced in glucose,amino acids (individual and in combination) Maillard reaction, under acidic conditions at 100 °C were determined and compared by trained panellist. Proline produced pleasant, flowery and fragrant aroma. Phenylalanine and tyrosine produced dried roses aroma. Alanine produced fruity and flowery odour, while aspartic acid and serine both produced pleasant, fruity aroma. Arginine, produced a pleasant, fruity and sour aroma at pH 5.2, but not at its natural pH. Glycine, lysine, threonine and valine produced a pleasant caramel-like odour. Isoleucine and leucine gave off a burnt caramel aroma. Methionine developed a fried potato odour. Cysteine and methionine produced savoury, meaty and soy sauce-like flavours. A combination of these amino acids produced different types of aroma, with the stronger note dominating the odour of the mixture. This study will help the prediction of flavour characteristics of hydrolysates from different protein sources. [source] Elucidation of Architectural Requirements from a Spacer in Supported Proline-Based Catalysts of Enantioselective Aldol ReactionADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 1-2 2009Kerem Goren Abstract In order to delineate the properties of the spacer architecture responsible for the strong positive dendritic effect exhibited by polymer-supported proline-based catalysts, we prepared two series of polystyrene-bound model catalysts. The first series was based on a linear and partially dendritic spacers (of reduced branching and valency) imitating the length of the second generation spacer, while the second series was based on the first generation dendron spacer with one functional (proline-terminated) and one non-functional arm. Comparative studies of the model and original (fully dendritic) catalysts in the asymmetric aldol reaction of aromatic aldehydes with acetone disclose the features characteristic to the dendritic architecture, such as proximity between the terminal catalytic units and enhanced branching, as crucial for inducing higher yield and enantioselectivity in catalysis. [source] Amine-Catalyzed Asymmetric Epoxidation of ,,,-Unsaturated AldehydesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7 2007Gui-Ling Zhao Abstract The direct organocatalytic enantioselective epoxidation of ,,,-unsaturated aldehydes with different peroxides is presented. Proline, chiral pyrrolidine derivatives, and amino acid-derived imidazolidinones catalyze the asymmetric epoxidation of ,,,-unsaturated aldehydes. In particular, protected commercially available ,,,-diphenyl- and ,,,-di(,-naphthyl)-2-prolinols catalyze the asymmetric epoxidation reactions of ,,,-unsaturated aldehydes with high diastereo- and enantioselectivities to furnish the corresponding 2-epoxy aldehydes in high yield with up to 97:3 dr and 98,% ee. The use of non-toxic catalysts, water and hydrogen peroxide, urea hydroperoxide or sodium percarbonate as the oxygen sources could make this reaction environmentally benign. In addition, one-pot direct organocatalytic asymmetric tandem epoxidation-Wittig reactions are described. The reactions were highly diastereo- and enantioselective and provide a rapid access to 2,4-diepoxy aldehydes. Moreover, a highly stereoselective one-pot organocatalytic asymmetric cascade epoxidation-Mannich reaction, which proceeds via the combination of iminium and enamine activation, is presented. The mechanism and stereochemistry of the amino acid- and chiral pyrrolidine-catalyzed direct asymmetric epoxidation of ,,,-unsaturated aldehydes are also discussed. [source] Proline-Catalyzed Imino-Diels,Alder Reactions: Synthesis of meso -2,6-Diaryl-4-piperidonesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 16-17 2006Fernando Aznar Abstract Amine-catalyzed imino-Diels,Alder reactions of acyclic ,,,-unsaturated ketones with imines have been developed. L -Proline catalyzed the in situ generation of 2-amino-1,3-butadienes to provide a stereoselective synthesis of meso -2,6-diaryl-4-piperidones in one direct step. [source] Microradiographic study on the effects of salivary proteins on in vitro demineralization of bovine enamelJOURNAL OF ORAL REHABILITATION, Issue 2 2005A. M. KIELBASSA summary, The aim of this investigation was to evaluate the effects of various proteins on in vitro demineralization of bovine enamel. From each of 100 bovine incisors two samples were prepared. The specimens were embedded in epoxy resin and polished up to 4000 grit. Subsequently, the specimens' surfaces were partly covered with nail varnish, thus serving as control of sound enamel. The specimens were divided randomly into five groups (n = 40) and demineralized in a solution of constant composition (pH 5·0; 10 days). For each subgroup of specimens (n = 10) 4 L were taken and either low (50% of medium conc.), medium, or high (150%) concentrations of the proteins [human albumin (100% conc. = 7 mg L,1), mucin (577·5 mg L,1), immunoglobulin G (IgG) (46 mg L,1), casein isolated from bovine milk (1·2 g L,1)] or amino acid [l -Proline (7 mg L,1)] were added to 1 L of the demineralizing solution, whereas 1 L served as control. Mineral loss and lesion depth (LD) were evaluated from microradiographs of thin sections (110 ,m) by a dedicated software package (TMR 1.24). No differences were found between the five control groups (P > 0·05; anova). Albumin, l -Proline, and IgG did not affect enamel demineralization, whereas the addition of both casein and mucin resulted in significant reductions of both mineral loss and LDs (P < 0·01; Tukey's test). Within the limitations of an in vitro study, the present investigation indicates that casein and mucin seem to affect enamel demineralization significantly. Thus, these proteins might be helpful as an additive to saliva substitutes or mouthwashes if the quality of saliva is altered. [source] Membrane stabilization by abscisic acid under cold aids proline in alleviating chilling injury in maize (Zea mays L.) cultured cellsPLANT CELL & ENVIRONMENT, Issue 8 2002W. P. Chen Abstract Previous studies of maize suspension-cultured cells showed that abscisic acid (ABA) treatment at warm temperatures improved the tolerance of cells to subsequent chilling. In the present study, it is shown that both ABA-treated and untreated maize cells accumulated proline in response to chilling. However, ABA-treated cells displayed less lipid peroxidation during chilling, and thus, unlike untreated cells, were able to retain the accumulated proline intracellularly. Proline application experiments indicate that an intracellular proline level higher than 2 µmole (g FW),1 prior to chilling was needed to meaningfully reduce chilling-enhanced lipid peroxidation and significantly improve chilling tolerance. The results suggest that total proline accumulation in ABA-treated as well as untreated cells during chilling was enough to potentially improve chilling tolerance, but proline leakage rendered the control cells unable to benefit from the endogenous synthesis of proline in relation to the alleviation of chilling injury. Proline participated in chilling tolerance improvement in ABA-treated maize cells, as evidenced by: (1) the inhibition of proline accumulation by l -methionine- d, l -sulphoximine (MSO), an inhibitor of glutamine synthetase, reduced ABA-improved chilling tolerance, and (2) the addition of glutamine into the medium prevented the MSO-induced reduction in chilling tolerance. The revised relationship between proline accumulation and membrane stability at cold is discussed in the light of these current findings. [source] The effect of drought and ultraviolet radiation on growth and stress markers in pea and wheatPLANT CELL & ENVIRONMENT, Issue 12 2001V. Alexieva Abstract It emerged recently that there is an inter-relationship between drought and ultraviolet-B (UV-B) radiation in plant responses, in that both stresses provoke an oxidative burst. The purpose of this investigation was to compare the effects and interaction of drought and UV-B in wheat and pea. The absence of changes in relative leaf water content (RWC) after UV-B treatments indicate that changes in water content were not involved. RWC was the main factor resulting in reduced growth in response to drought. Increases in anthocyanin and phenols were detected after exposure to UV-B. The increases do not appear to be of sufficient magnitude to act as a UV-B screen. UV-B application caused greater membrane damage than drought stress, as assessed by lipid peroxidation as well as osmolyte leakage. An increase in the specific activities of antioxidant enzymes was measured after UV-B alone as well as after application to droughted plants. Proline increased primarily in drought-stressed pea or wheat. Proline may be the drought-induced factor which has a protective role in response to UV-B. The physiological and biochemical parameters measured indicate the UV-B light has stronger stress effectors than drought on the growth of seedlings of both species. The two environmental stresses acted synergistically to induce protective mechanisms in that pre-application of either stress reduced the damage caused by subsequent application of the other stress. [source] Effect of the N1 residue on the stability of the ,-helix for all 20 amino acidsPROTEIN SCIENCE, Issue 3 2001Duncan A.E. Cochran Abstract N1 is the first residue in an ,-helix. We have measured the contribution of all 20 amino acids to the stability of a small helical peptide CH3CO-XAAAAQAAAAQAAGY-NH2 at the N1 position. By substituting every residue into the N1 position, we were able to investigate the stabilizing role of each amino acid in an isolated context. The helix content of each of the 20 peptides was measured by circular dichroism (CD) spectroscopy. The data were analyzed by our modified Lifson-Roig helix-coil theory, which includes the n1 parameter, to find free energies for placing a residue into the N1 position. The rank order for free energies is Asp,, Ala > Glu, > Glu0 > Trp, Leu, Ser > Asp0, Thr, Gln, Met, Ile > Val, Pro > Lys+, Arg, His0 > Cys, Gly > Phe > Asn, Tyr, His+. N1 preferences are clearly distinct from preferences for the preceding N-cap and ,-helix interior. pKa values were measured for Asp, Glu, and His, and protonation-free energies were calculated for Asp and Glu. The dissociation of the Asp proton is less favorable than that of Glu, and this reflects its involvement in a stronger stabilizing interaction at the N terminus. Proline is not energetically favored at the ,-helix N terminus despite having a high propensity for this position in crystal structures. The data presented are of value both in rationalizing mutations at N1 ,-helix sites in proteins and in predicting the helix contents of peptides. [source] Two-dimensional reference map for the basic proteome of the human dorsolateral prefrontal cortex (dlPFC) of the prefrontal lobe region of the brainPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 13 2010Ciara A. McManus Abstract We describe a 2-DE proteomic reference map containing 227 basic proteins in the dorsolateral prefrontal cortex region of the human brain. Proteins were separated in the first dimension on pH 6,11 IPG strips using paper-bridge loading and on 12% SDS-PAGE in the second dimension. Proteins were subsequently identified by MS and spectra were analyzed using an in-house proteomics data analysis platform, Proline. The 2-DE reference map is available via the UCD 2-DE Proteome Database (http://proteomics-portal.ucd.ie:8082) and can also be accessed via the WORLD-2DPAGE Portal (http://www.expasy.ch/world-2dpage/). The associated protein identification data have been submitted to the PRIDE database (accession numbers 10018,10033). Separation of proteins in the basic region resolves more membrane associated proteins relevant to the synaptic pathology central to many neurological disorders. The 2-DE reference map will aid with further characterisation of neurological disorders such as bipolar and schizophrenia. [source] 2D Random Organization of Racemic Amino Acid Monolayers Driven by Nanoscale Adsorption Footprints: Proline on Cu(110),ANGEWANDTE CHEMIE, Issue 13 2010Matthew Forster In die Fußstapfen getreten: Racemisches (R,S) - Prolin bildet auf Cu(110) Reihen aus zufällig angeordneten chiralen Aminosäuren, was belegt, dass die Anordnung nicht durch die Molekülchiralität festgelegt wird. Vielmehr wird sie durch ein streng heterochirales Adsorptions-,Fußstapfen"-Templat bestimmt, in dem jede Adsorptionsposition von jedem der Enantiomere besetzt werden kann (siehe Bild), was eine ungeordnete zweidimensionale feste Lösung ergibt. [source] Synthesis and Biological Activity of Endomorphin-2 Analogs Incorporating Piperidine-2-, 3- or 4-Carboxylic Acids Instead of Proline in Position 2CHEMICAL BIOLOGY & DRUG DESIGN, Issue 1 2008Renata Staniszewska Novel endomorphin-2 (EM-2) analogs have been synthesized, incorporating unnatural amino acids with six-membered heterocyclic rings, such as piperidine-2-, 3- and 4-carboxylic acids (Pip, Nip and Inp, respectively) instead of Pro in position 2. [(R)-Nip2]EM-2 displayed an extremely high affinity for the ,-opioid receptor with IC50 = 0.04 ± 0.01 nm in comparison with IC50 = 0.69 ± 0.03 nm for EM-2. This analog was also very potent in the aequorin luminescence-based functional calcium assay and showed significantly enhanced stability in rat brain homogenate. [source] ChemInform Abstract: Influence of ,-Methyl Substitution of Proline-Based Organocatalysts on the Asymmetric ,-Oxidation of Aldehydes.CHEMINFORM, Issue 41 2009Sok-Teng Tong Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Asymmetric Conjugate Addition of Unmodified Propionaldehyde to ,-Nitrostyrenes Catalyzed by Readily Available Proline-Based Dipeptidols.CHEMINFORM, Issue 23 2009Ren-Yong Yang Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] A Multifunctional Proline-Based Organic Catalyst for Enantioselective Aldol Reactions.CHEMINFORM, Issue 12 2007Stefania Guizzetti Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Combined Proline,Surfactant Organocatalyst for the Highly Diastereo- and Enantioselective Aqueous Direct Cross-Aldol Reaction of Aldehydes.CHEMINFORM, Issue 50 2006Yujiro Hayashi Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Highly Enantioselective Synthesis of Rigid, Quaternary 1,4-Benzodiazepine-2,5-diones Derived from Proline.CHEMINFORM, Issue 12 2006Stephanie MacQuarrie-Hunter Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Diastereoselective Aldol Reaction of N,N-Dibenzyl-,-amino Aldehydes with Ketones Catalyzed by Proline.CHEMINFORM, Issue 30 2004Qiangbiao Pan Abstract For Abstract see ChemInform Abstract in Full Text. [source] Poly(Ethylene Glycol)-Supported Proline: A Versatile Catalyst for the Enantioselective Aldol and Iminoaldol Reactions.CHEMINFORM, Issue 44 2002Maurizio Benaglia Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: 1,3-Dipolar Cycloaddition Reactions of Ester-Stabilized Azomethine Ylides with Acrolein: A One-Pot Regio- and Stereoselective Synthesis of N-Substituted 4-Formyl-5-vinyl Proline Carboxylates.CHEMINFORM, Issue 21 2002Yu Gui Gu Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Molecular Structure of ProlineCHEMISTRY - A EUROPEAN JOURNAL, Issue 18 2004Wesley D. Allen Dr. Abstract The molecular structures of the two lowest-energy conformers of proline, Pro- I and Pro- II, have been characterized by ab initio electronic structure computations. An extensive MP2/6-31G* quartic force field for Pro- I, containing 62,835 unique elements in the internal coordinate space, was computed to account for anharmonic vibrational effects, including total zero-point contributions to isotopomeric rotational constants. New re and improved r0 least-squares structural refinements were performed to determine the heavy-atom framework of Pro- I, based on experimentally measured (A. Lesarri, S. Mata, E. J. Cocinero, S. Blanco, J. C. Lopez, J. L. Alonso, Angew. Chem.2002, 114, 4867; Angew. Chem. Int. Ed.2002, 41, 4673) rotational constant sets of nine isotopomers and our ab initio data for structural constraints and zero-point vibrational (ZPV) shifts. Without the ab initio constraints, even the extensive set of empirical rotational constants cannot satisfactorily fix the molecular structure of the most stable conformer of proline, a 17-atom molecule with no symmetry. After imposing the ab initio constraints, excellent agreement between theory and experiment is found for the heavy-atom geometric framework, the root-mean-square (rms) residual of the empirical rotational constant fit being cut in half by adding ZPV corrections. The most significant disparity, about 0.07 Å, between the empirical and the best ab initio structures, concerns the r(N,,,H) distance of the intramolecular hydrogen bond. Some of the experimental quartic centrifugal distortion constants assigned to Pro- II have been corrected based on data obtained from a theoretical force field. [source] Caenorhabditis elegans expresses three functional profilins in a tissue-specific mannerCYTOSKELETON, Issue 1 2006D. Polet Abstract Profilins are actin binding proteins, which also interact with polyphosphoinositides and proline-rich ligands. On the basis of the genome sequence, three diverse profilin homologues (PFN) are predicted to exist in Caenorhabditis elegans. We show that all three isoforms PFN-1, PFN-2, and PFN-3 are expressed in vivo and biochemical studies indicate they bind actin and influence actin dynamics in a similar manner. In addition, they bind poly(L -proline) and phosphatidylinositol 4,5-bisphosphate micelles. PFN-1 is essential whereas PFN-2 and PFN-3 are nonessential. Immunostainings revealed different expression patterns for the profilin isoforms. In embryos, PFN-1 localizes in the cytoplasm and to the cell,cell contacts at the early stages, and in the nerve ring during later stages. During late embryogenesis, expression of PFN-3 was specifically detected in body wall muscle cells. In adult worms, PFN-1 is expressed in the neurons, the vulva, and the somatic gonad, PFN-2 in the intestinal wall, the spermatheca, and the pharynx, and PFN-3 localizes in a striking dot-like fashion in body wall muscle. Thus the model organism Caenorhabditis elegans expresses three profilin isoforms and is the first invertebrate animal with tissue-specific profilin expression. Cell Motil. Cytoskeleton, 2006.© 2005 Wiley-Liss, Inc. [source] Dipeptidyl peptidase-IV inhibitors: a major new class of oral antidiabetic drugDIABETES OBESITY & METABOLISM, Issue 2 2007Iskandar Idris Exploiting the incretin effect to develop new glucose-lowering treatments has become the focus of intense research. One successful approach has been the development of oral inhibitors of dipeptidyl peptidase-IV (DPP-IV). These drugs reversibly block DPP-IV-mediated inactivation of incretin hormones, for example, glucagon-like peptide 1 (GLP-1) and also other peptides that have alanine or proline as the penultimate N-terminal amino acid. DPP-IV inhibitors, therefore, increase circulating levels and prolong the biological activity of endogenous GLP-1, but whether this is sufficient to fully explain the substantial reduction in haemoglobin A1c (HbA1c) and associated metabolic profile remains open to further investigation. DPP-IV inhibitors such as vildagliptin and sitagliptin have been shown to be highly effective antihyperglycaemic agents that augment insulin secretion and reduce glucagon secretion via glucose-dependent mechanisms. This review summarizes the major clinical trials with DPP-IV inhibitors as monotherapy and as add-on therapy in patients with type 2 diabetes. The magnitude of HbA1c reduction with DPP-IV inhibitors depends upon the pretreatment HbA1c values, but there seems to be no change in body weight, and very low rates of hypoglycaemia and gastrointestinal disturbance with these agents. DPP-IV inhibitors represent a major new class of oral antidiabetic drug and their metabolic profile offers a number of unique clinical advantages for the management of type 2 diabetes. [source] Autoradiographic observations on developing and growing claws of reptilesACTA ZOOLOGICA, Issue 2 2010Lorenzo Alibardi Abstract Alibardi, L. 2010. Autoradiographic observations on developing and growing claws of reptiles. ,Acta Zoologica (Stockholm) 91: 233,241 The present qualitative autoradiographic analysis aims to present the main features of morphogenesis and growth of claws in reptiles. Lizard embryos treated with tritiated thymidine reveal that epidermal cell proliferation in terminal digits is prevalent in the dorsal side and gives origin to the curved unguis of the claw. Less proliferation occurs in the ventral side of the digit tip where the concave sub-unguis is derived. Adult claws of a turtle show that thymidine-labelled cells are present along most of the epidermis of the claw, especially at the claw tip. Also, injection of tritiated histidine and proline, indicating active protein synthesis, confirm autoradiographic labelling along most of the epidermis of claws, in particular at the apical tip. The present study indicates that proximal matrix regions, as have been described in mammalian nails, are absent in reptiles. This pattern of claw growth probably derives from that of terminal digital scales. In fact reptilian (and avian) claws are formed from a modification of scales, a different condition from that present in mammals. [source] Biological and biochemical differences between in vitro- and in vivo-reared Exorista larvarumENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2006Maria Luisa Dindo Abstract Quantitative and qualitative parameters of Exorista larvarum (L.) (Diptera: Tachinidae) reared on two insect-material-free artificial media and in the factitious host Galleria mellonella L. (Lepidoptera: Pyralidae) were compared. Significantly higher puparial yields and weights were obtained in both a milk-based and a veal homogenate-based medium than in the factitious host. Longevity and parasitization rates were not different between the in vitro- and in vivo-reared flies. Despite the greater puparial weight of the veal medium-reared E. larvarum females, the number of eggs laid by these females on host larvae was not higher than that of females reared under the other two rearing conditions. Moreover, in a complementary experiment, with homogeneous puparial weights of milk medium- and host-reared females, the former oviposited fewer eggs. Hence, puparial weight alone is not a reliable quality parameter for E. larvarum reared on artificial media. Lower amino acid content, with a deficiency in aromatic amino acids and an excess in proline, was found for in vitro third instar parasitoid larvae reared on both media compared to the in vivo-reared ones. These results suggest a correlation between the amino acid deficiency and imbalance of medium-reared larvae and the lower number of eggs laid by the females obtained. [source] Lack of CbrB in Pseudomonas putida affects not only amino acids metabolism but also different stress responses and biofilm developmentENVIRONMENTAL MICROBIOLOGY, Issue 6 2010Cristina I. Amador Summary The CbrAB two-component system has been described in certain species of Pseudomonads as a global regulatory system required for the assimilation of several amino acids (e.g. histidine, proline or arginine) as carbon or carbon and nitrogen sources. In this work, we used global gene expression and phenotypic analyses to characterize the roles of the CbrAB system in Pseudomonas putida. Our results show that CbrB is involved in coordination with the nitrogen control system activator, NtrC, in the uptake and assimilation of several amino acids. In addition, CbrB affects other carbon utilization pathways and a number of apparently unrelated functions, such as chemotaxis, stress tolerance and biofilm development. Based on these new findings, we propose that CbrB is a high-ranked element in the regulatory hierarchy of P. putida that directly or indirectly controls a variety of metabolic and behavioural traits required for adaptation to changing environmental conditions. [source] Bentazon triggers the promotion of oxidative damage in the Portuguese ricefield cyanobacterium Anabaena cylindrica: Response of the antioxidant systemENVIRONMENTAL TOXICOLOGY, Issue 5 2010Victor Galhano Abstract Rice fields are frequently exposed to environmental contamination by herbicides and cyanobacteria, as primary producers of these aquatic ecosystems, are adversely affected. Anabaena cylindrica is a cyanobacterium with a significantly widespread occurrence in Portuguese rice fields. This strain was studied throughout 72 h in laboratory conditions for its stress responses to sublethal concentrations (0.75,2 mM) of bentazon, a selective postemergence herbicide recommended for integrated weed management in rice, with special reference to oxidative stress, role of proline and intracellular antioxidant enzymes in herbicide-induced free radicals detoxification. Activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione S -transferase (GST) increased in a time- and herbicide dose-response manner and were higher than those in the control samples after 72 h. A time- and concentration-dependent increase of malondialdehyde (MDA) levels and the enhanced cell membrane leakage following bentazon exposure are indicative of lipid peroxidation, free radicals formation, and oxidative damage, while increased amounts of SOD, CAT, APX, GST, and proline indicated their involvement in free radical scavenging mechanisms. The appreciable decline in the reduced glutathione (GSH) pool after 72 h at higher bentazon concentrations could be explained by the reduction of the NADPH-dependent glutathione reductase (GR) activity. The obtained results suggested that the alterations of antioxidant systems in A. cylindrica might be useful biomarkers of bentazon exposure. As the toxic mechanism of bentazon is a complex phenomenon, this study also adds relevant findings to explain the oxidative stress pathways of bentazon promoting oxidative stress in cyanobacteria. © 2010 Wiley Periodicals, Inc. Environ Toxicol, 2010. [source] Does the Giant Wood Spider Nephila pilipes Respond to Prey Variation by Altering Web or Silk Properties?ETHOLOGY, Issue 4 2007I-Min Tso Recent studies demonstrated that orb-weaving spiders may alter web architectures, the amount of silk in webs, or the protein composition of silks in response to variation in amount or type of prey. In this study, we conducted food manipulations to examine three mechanisms by which orb-weaving spiders may adjust the performance of webs to variation in prey by altering the architectures of webs, making structural changes to the diameters of silk threads, and manipulating the material properties or amino acid composition of silk fibers. We fed Nephila pilipes two different types of prey, crickets or flies, and then compared orb structure and the chemical and physical properties of major ampullate (MA) silk between groups. Prey type did not affect orb structures in N. pilipes, except for mesh size. However, MA silk diameter and the stiffness of orbs constructed by spiders fed crickets were significantly greater than for the fly group. MA fibers forcibly silked from N. pilipes fed crickets was significantly thicker, but less stiff, than silk from spiders fed flies. Spiders in the cricket treatment also produced MA silk with slightly, but statistically significantly, more serine than silk from spiders in the fly treatment. Percentages of other major amino acids (proline, glycine, and glutamine) did not differ between treatments. This study demonstrated that orb-weaving spiders can simultaneously alter some structural and material properties of MA silk, as well as the physical characteristics of webs, in response to different types of prey. [source] | |||||||||||||||||||||||||||||||||||||||||||