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941.
André Nel 《法国昆虫学会纪事》2013,49(1):23-29
A new deposit of Lower Cretaceous amber, found in Charente-Maritime (SW France) has yielded an important entomofauna with numerous arthropod associations characteristic of moist ground. We describe a new species of Dolichopodidae: ‘Microphorinae’(Diptera: Empidoidea), Microphorites deploegi n. sp. on the basis of seven male and female specimens of exceptional state of preservation. This genus was previously only known from Lebanese amber of the Lower Cretaceous. The present discovery supports a reconstruction of the palaeoenvironment as a sandy beach along the sea, under a warm climate. 相似文献
942.
The first fossil representative of the jewel damselflies (Calopterygoidea: Chlorocyphidae), a family of large, prominent, and often brilliantly colored Old World tropical Zygoptera, is described and figured. Chlorocypha cordasevae n. sp. was recovered from the Late Miocene (Early Pannonian, Serravalian to Tortonian, c.11 Ma) locality of Paldau, in the Styrian Basin, Austria. The fossil seems to be related to the African genus Chlorocypha Fraser, and within a larger group of African genera also including Stenocypha Dijkstra, Africocypha Pinhey, and Platycypha Fraser, and collectively set apart from southern Asiatic genera. The discovery of a central European species of Chlorocypha as recently as the Late Miocene reveals a much wider range to the family than its generally disjunctive modern distribution, demonstrating a Neogene contraction to their range, likely in connection with climatic cooling, drying, and developing seasonality. Modern chlorocyphids live under warm, humid climates, and the presence of C. cordasevae in the Pannonian fauna of Paldau further corroborates such a subtropical paleoclimate for the locality at that time. 相似文献
943.
Gládis de Oliveira Jucoski José Cambraia Cleberson Ribeiro Juraci Alves de Oliveira Sérgio Oliveira de Paula Marco Antonio Oliva 《Acta Physiologiae Plantarum》2013,35(5):1645-1657
In excess, iron can induce the production and accumulation of reactive oxygen species (ROS), causing oxidative stress. The objective of this work was to evaluate the impact of toxic concentrations of iron (Fe) on the antioxidative metabolism of young Eugenia uniflora plants. Forty-five-day-old plants grown in Hoagland nutrient solution, pH 5.0, were treated with three Fe concentrations, in the form of FeEDTA, during three periods of time. At the end of the treatment, the plants were harvested and relative growth rate, iron content, lipid peroxidation and enzymes and metabolites of the antioxidative metabolism were determined. Iron-treated plants showed higher iron contents, reduced relative growth rates and iron toxicity symptoms in both leaves and roots. There was an increase in lipid peroxidation with increasing Fe, only in the leaves. The enzymatic activities of superoxide dismutase (SOD) and glutathione reductase (GR) increased with increasing Fe concentration and treatment exposure time. The activities of catalase (CAT), peroxidase (POX) and ascorbate peroxidase (APX) also increased with increasing Fe concentration but decreased with increasing treatment exposure time. Glutathione peroxidase activity (GPX) decreased with increasing Fe concentration and exposure time. The ascorbate (AA) and reduced glutathione (GSH) contents and the AA/DHA and GSH/GSSG ratios, in general, increased with increasing Fe concentration and treatment exposure time. The results indicate that under toxic levels of Fe, young E. uniflora plants suffer increased oxidative stress, which is ameliorated through changes in the activities of antioxidative enzymes and in the contents of the antioxidants AA and GSH. 相似文献
944.
Sebastian Peter Matthias Kinne René Ullrich Gernot Kayser Martin Hofrichter 《Enzyme and microbial technology》2013,52(6-7):370-376
Unspecific peroxygenases (EC 1.11.2.1) represent a group of secreted heme-thiolate proteins that are capable of catalyzing the mono-oxygenation of diverse organic compounds, using only H2O2 as a co-substrate. Here we show that the peroxygenase secreted by the fungus Agrocybe aegerita catalyzed the oxidation of 20 different alkenes. Five branched alkenes, among them 2,3-dimethyl-2-butene and cis-2-butene, as well as propene and butadiene were epoxidized with complete regioselectivity. Longer linear alkenes with a terminal double bond (e.g. 1-octene) and cyclic alkenes (e.g. cyclohexene) were converted into the corresponding epoxides and allylic hydroxylation products; oxidation of the cyclic monoterpene limonene yielded three oxygenation products (two epoxides and an alcohol). In the case of 1-alkenes, the conversion occurred with moderate stereoselectivity, in which the preponderance for the (S)-enantiomer reached up to 72% ee for the epoxide product. The apparent Michaelis–Menten constant (Km) for the epoxidation of the model substrate 2-methyl-2-butene was 5 mM, the turnover number (kcat) 1.3 × 103 s?1 and the calculated catalytic efficiency, kcat/Km, was 2.5 × 105 M?1 s?1. As epoxides represent chemical building blocks of high relevance, new enzymatic epoxidation pathways are of interest to complement existing chemical and biotechnological approaches. Stable and versatile peroxygenases as that of A. aegerita may form a promising biocatalytic platform for the development of such enzyme-based syntheses. 相似文献
945.
Gonzalo Castillo‐Campos José G. García‐Franco María Luisa Martínez 《Nordic Journal of Botany》2013,31(4):449-452
Spathacanthus magdalenae Cast.‐Campos (Acanthaceae) is described and illustrated as a new riparian forest species from central Veracruz and from the eastern slopes of the volcano Cofre de Perote, Mexico. The new species is similar to Spathacanthus parviflorus, but differs in wider leaves and longer corolla tube. A key to all four species of Spathacanthus is provided. 相似文献
946.
947.
Leandro Bueno Bergantin Cláudio Fontes Souza Regiane Miranda Ferreira Soraya Soubhi Smaili Neide Hyppolito Jurkiewicz Afonso Caricati-Neto Aron Jurkiewicz 《Cell calcium》2013
It is well established that reduction of Ca2+ influx through L-type voltage-dependent Ca2+ channel (L-type VDCC), or increase of cytosolic cAMP concentration ([cAMP]c), inhibit contractile activity of smooth muscles in response to transmitters released from sympathetic nerves. Surprisingly, in this work we observed that simultaneous administration of L-type VDCC blocker (verapamil) and [cAMP]c enhancers (rolipram, IBMX and forskolin) potentiated purinergic contractions evoked by electrical field stimulation of rat vas deferens, instead of inhibiting them. These results, including its role in sympathetic transmission, can be considered as a “calcium paradox”. On the other hand, this potentiation was prevented by reduction of [cAMP]c by inhibition of adenylyl cyclase (SQ 22536) or depletion of Ca2+ storage of sarco-endoplasmic reticulum by blockade of Ca2+ reuptake (thapsigargin). In addition, cytosolic Ca2+ concentration ([Ca2+]c) evaluated by fluorescence microscopy in rat adrenal medullary slices was significantly reduced by verapamil or rolipram. In contrast, simultaneous incubation of adrenal slices with these compounds significantly increased [Ca2+]c. This effect was prevented by thapsigargin. Thus, a reduction of [Ca2+]c due to blockade of Ca2+ influx through L-type VDCC could stimulate adenylyl cyclase activity increasing [cAMP]c thereby stimulating Ca2+ release from endoplasmic reticulum, resulting in augmented transmitter release in sympathetic nerves and contraction. 相似文献
948.
Nabila Haddad Margarida Saramago Rute?G. Matos Hervé Prévost Cecília?M. Arraiano 《Bioscience reports》2013,33(6)
Campylobacter jejuni is a foodborne bacterial pathogen, which is now considered as a leading cause of human bacterial gastroenteritis. The information regarding ribonucleases in C. jejuni is very scarce but there are hints that they can be instrumental in virulence mechanisms. Namely, PNPase (polynucleotide phosphorylase) was shown to allow survival of C. jejuni in refrigerated conditions, to facilitate bacterial swimming, cell adhesion, colonization and invasion. In several microorganisms PNPase synthesis is auto-controlled in an RNase III (ribonuclease III)-dependent mechanism. Thereby, we have cloned, overexpressed, purified and characterized Cj-RNase III (C. jejuni RNase III). We have demonstrated that Cj-RNase III is able to complement an Escherichia coli rnc-deficient strain in 30S rRNA processing and PNPase regulation. Cj-RNase III was shown to be active in an unexpectedly large range of conditions, and Mn2+ seems to be its preferred co-factor, contrarily to what was described for other RNase III orthologues. The results lead us to speculate that Cj-RNase III may have an important role under a Mn2+-rich environment. Mutational analysis strengthened the function of some residues in the catalytic mechanism of action of RNase III, which was shown to be conserved. 相似文献
949.
Michel Ronjat José Pablo Finkelstein Paola Llanos Luis Montecinos Hicham Bichraoui Michel De Waard Cecilia Hidalgo Ricardo Bull 《Cell calcium》2013,53(5-6):357-365
The scorpion toxin maurocalcine acts as a high affinity agonist of the type-1 ryanodine receptor expressed in skeletal muscle. Here, we investigated the effects of the reducing agent dithiothreitol or the oxidizing reagent thimerosal on type-1 ryanodine receptor stimulation by maurocalcine. Maurocalcine addition to sarcoplasmic reticulum vesicles actively loaded with calcium elicited Ca2+ release from native vesicles and from vesicles pre-incubated with dithiothreitol; thimerosal addition to native vesicles after Ca2+ uptake completion prevented this response. Maurocalcine enhanced equilibrium [3H]-ryanodine binding to native and to dithiothreitol-treated reticulum vesicles, and increased 5-fold the apparent Ki for Mg2+ inhibition of [3H]-ryanodine binding to native vesicles. Single calcium release channels incorporated in planar lipid bilayers displayed a long-lived open sub-conductance state after maurocalcine addition. The fractional time spent in this sub-conductance state decreased when lowering cytoplasmic [Ca2+] from 10 μM to 0.1 μM or at cytoplasmic [Mg2+] ≥ 30 μM. At 0.1 μM [Ca2+], only channels that displayed poor activation by Ca2+ were readily activated by 5 nM maurocalcine; subsequent incubation with thimerosal abolished the sub-conductance state induced by maurocalcine. We interpret these results as an indication that maurocalcine acts as a more effective type-1 ryanodine receptor channel agonist under reducing conditions. 相似文献
950.
Yana Chen Kevork Hagopian Douglas Bibus José?M. Villalba Guillermo López-Lluch Plácido Navas Kyoungmi Kim Roger?B. McDonald Jon?J. Ramsey 《Bioscience reports》2013,33(1)
To investigate the role mitochondrial membrane lipids play in the actions of CR (calorie restriction), C57BL/6 mice were assigned to four groups (control and three 40% CR groups) and the CR groups were fed diets containing soya bean oil (also in the control diet), fish oil or lard. The fatty acid composition of the major mitochondrial phospholipid classes, proton leak and H2O2 production were measured in liver mitochondria following 1 month of CR. The results indicate that mitochondrial phospholipid fatty acids reflect the PUFA (polyunsaturated fatty acid) profile of the dietary lipid sources. CR significantly decreased the capacity of ROS (reactive oxygen species) production by Complex III but did not markedly alter proton leak and ETC (electron transport chain) enzyme activities. Within the CR regimens, the CR-fish group had decreased ROS production by both Complexes I and III, and increased proton leak when compared with the other CR groups. The CR-lard group showed the lowest proton leak compared with the other CR groups. The ETC enzyme activity measurements in the CR regimens showed that Complex I activity was decreased in both the CR-fish and CR-lard groups. Moreover, the CR-fish group also had lower Complex II activity compared with the other CR groups. These results indicate that dietary lipid composition does influence liver mitochondrial phospholipid composition, ROS production, proton leak and ETC enzyme activities in CR animals. 相似文献