Diaminoterephthalate turn-on fluorescence probes for thiols--tagging of recoverin and tracking of its conformational change

Diaminoterephthalates with a maleimide moiety were synthesized and used as fluorescence dyes for sensing thiols. Whereas these "NiWa Blue" dyes showed no emission, the conjugate addition of a thiol to the maleimide group turned on a fluorescence at about 400 nm when irradiating the dye at 338 nm. The neuronal-calcium sensor protein recoverin possesses a single cysteine residue at position 39, which reacts with NiWa Blue, and is therefore labeled by a fluorophore with an emission at about 440 nm. In the absence of Ca(2+), irradiation at 280 nm of a tryptophan residue in close proximity to Cys-bound NiWa Blue lead to strong FRET, which was detected by emission of the dye at 440 nm. In the presence of Ca(2+), the protein holds a conformation with distal Trp and Cys residues, thus FRET of irradiated Trp to Cys-bound NiWa Blue was significantly weakened.     

Effects of cyclic lipodepsipeptide structural modulation on stability, antibacterial activity, and human cell toxicity

Bacterial infections are becoming increasingly difficult to treat due to the development and spread of antibiotic resistance. Therefore, identifying novel antibacterial targets and new antibacterial agents capable of treating infections by drug-resistant bacteria is of vital importance. The structurally simple yet potent fusaricidin or LI-F class of natural products represents a particularly attractive source of candidates for the development of new antibacterial agents. We synthesized 18 fusaricidin/LI-F analogues and investigated the effects of structure modification on their conformation, serum stability, antibacterial activity, and toxicity toward human cells. Our findings show that substitution of an ester bond in depsipeptides with an amide bond may afford equally potent analogues with improved stability and greatly decreased cytotoxicity. The lower overall hydrophobicity/amphiphilicity of amide analogues in comparison with their parent depsipeptides, as indicated by HPLC retention times, may explain the dissociation of antibacterial activity and human cell cytotoxicity. These results indicate that amide analogues may have significant advantages over fusaricidin/LI-F natural products and their depsipeptide analogues as lead structures for the development of new antibacterial agents.     

Phytanic acid concentrations and diastereomer ratios in milk fat during changes in the cow’s feed from concentrate to hay and back

The phytanic acid content in milk correlates with the amount of green items in the cows’ feed. For this reason, the four-fold methyl-branched fatty acid has been suggested as a potential marker for the authentication of organic milk. In this study, we attempted to provide further support for this idea by studying the progression of the phytanic acid level and diastereomer ratio in milk fat by transition of the diets from high proportions of concentrate (typical “conventional” feed) to hay (typical “organic” feed in winter) and back to “conventional” feed. Milk samples taken from three cows were analyzed on both the phytanic acid concentration and diastereomer distribution. The cows were initially fed with “conventional” feed (ground feed with high portions (30–45?%) of concentrate), then the feed was changed within 1?week to 100?% hay (“organic” feed), and after ~6?weeks, the feed of two cows was changed back to the initial feed with concentrate (phase C_b). During the “conventional” feeding at the beginning of the experiment, the phytanic acid concentration was low (100–130?mg/100?g milk fat). When the feed was changed to hay (“organic” feed), the phytanic acid concentration immediately increased to a stable level of about 160?mg/100?g lipids. Changing back the feed to “conventional” feed, the phytanic acid concentration dropped immediately back below the value measured in the initial phase. Likewise, the SRR/RRR-diastereomer distribution of phytanic acid in the milk was an excellent indicator for the changes in the cows’ feed. While the SRR/RRR-diastereomer ratio was >1.5 during “conventional” feeding, it immediately decreased to equal amounts of both diastereomers when hay was supplied as feed. Abandonment of concentrate in conventional feeding increased the phytanic acid content but the SRR-diastereomer was still dominant and thus the SRR/RRR-diastereomer ratio was different to organic milk. Our results indicate that both parameters, i.e., the phytanic acid content and SRR/RRR-diastereomer ratio need to be measured for authentication of organic milk.     

Enhancing the polyphenol content of a red-fleshed Japanese plum (Prunus salicina Lindl.) nectar by incorporating a polyphenol-rich extract from the skins

BACKGROUND: Plum skins are a waste product generated during production of plum juice or pulp. Polyphenols, shown to have various health‐promoting properties, can be recovered from this waste product. Red‐fleshed plum nectar formulations containing plum skin extract in varying amounts were characterised in terms of intensity of sensory attributes, consumer acceptability, colour, polyphenol content and antioxidant activity. Commercial beverages containing red fruits were used as benchmarks. RESULTS: The polyphenolic profile of the plum skin extract was similar to that of the pulp, including anthocyanins, flavonols, flavan‐3‐ols and a phenolic acid. Addition of the extract to plum nectar, which enhanced the colour, polyphenol content and antioxidant capacity, was limited by its negative sensory impact. The formulations were deemed acceptable by consumers, although a decrease in positive sensory attributes (plum flavour, plum aroma and sweetness) and an increase in negative sensory attributes (plant‐like flavour, plant‐like aroma, acidity and astringency) were observed with increasing skin extract content. The formulations compared favourably with commercial beverages in terms of colour total polyphenol content and antioxidant activity. CONCLUSION: Plum skins were successfully used to enhance the functional status of plum nectar. Use of a functional ingredient from plum skins is, therefore, a feasible value‐addition strategy. Copyright © 2012 Society of Chemical Industry     

老君庙油田测井二次解释方法研究

老油田由于开发年代久远、测井系列老、水淹特征复杂等实际情况,给测井二次解释带来了很大的困难.以老君庙油田L油藏为研究对象,利用地质统计学领域的变差函数块金效应对电阻率曲线进行标准化.采用沉积相控下的电阻率建模思路,建立了不同沉积环境的储层属性模型并进行测井解释.利用常规曲线组合进行水淹层定性识别,通过联立方程组的方法进行水淹层定量评价.经试油生产验证,解释成果准确性较高,为油田落实石油地质储量以及编制开发方案提供了依据.     

Validation of a Real-Time PCR On-Site Quantification Method for MON810 Maize

A rapid on-, or near-site, quantitative method for use as a pre-harvest predictive decision, or co-existence monitoring, tool for adventitious genetically modified (GM) presence has been developed. Based on a laboratory-based protocol for real-time (RT) quantification of the MON810 GM event in maize kernels, the duplex RT polymerase chain reaction method was constructed around the portable Cepheid SmartCyclerII platform, requiring only modest support infrastructure for field application. Validation through an international ring trial showed good compliance with minimum assay performance requirements as defined by the European Network of GMO Laboratories (RSD_r = 18.5%; RSD_R = 32.8; Bias = 26.7%).     

Can δ15N in lettuce tissues reveal the use of synthetic nitrogen fertiliser in organic production?

BACKGROUND: The nitrogen isotopic fingerprint (δ¹⁵N) is reported to be a promising indicator for differentiating between organically and conventionally grown vegetables. However, the effect on plant δ¹⁵N of split nitrogen fertilisation, which could enable farmers to cover up the use of synthetic fertiliser, is not well studied. In this study the use of δ¹⁵N in lettuce as a potential marker for identifying the use of synthetic nitrogen fertiliser was tested on pot‐grown lettuce (Lactuca sativa L.) treated with synthetic and organic nitrogen fertilisers (single or split application). The effect of combined usage of synthetic and organic fertilisers on δ¹⁵N was also investigated. RESULTS: The δ¹⁵N values of whole plants treated with different fertilisers differed significantly when the fertiliser was applied in a single treatement. However, additional fertilisation (with isotopically the same or different fertiliser) did not cause a significant alteration of plant δ¹⁵N. CONCLUSION: The findings of the study suggest that the δ¹⁵N value of lettuce tissues could be used as a rough marker to reveal the history of nitrogen fertilisation, but only in the case of single fertiliser application. However, if the difference in δ¹⁵N between the applied synthetic and organic nitrogen fertilisers was > 9.1‰, the detection of split and combined usage of the fertilisers would have greater discriminatory power. Copyright © 2010 Society of Chemical Industry     

Antioxidative activities and chemical characterization of polysaccharides extracted from the basidiomycete Schizophyllum commune

Antioxidant properties of hot water extract (HWE), hot water extracted polysaccharides (HWP) and hot alkali extracted polysaccharides (HWAE) were obtained from fruiting bodies of the wild basidiomycete Schizophyllum commune. All extracts contained both α- and β-glucans as determined by Megazyme β-glucan assay kit. Glucose was found by TLC and NMR to be the prevalent monosaccharide in all extracts. Total phenol contents were in descending order of HWP ≈ HWE > HWAE. Median effective concentrations (EC₅₀ values) of antioxidant activities were 8.3 ± 0.1, 6.9 ± 0.0 and 8.9 ± 0.1 mg/mL, and of the DPPH scavenging activity 0.8 ± 0.0, 0.6 ± 0.0 and 1.8 ± 0.0 mg/mL, for HWE, HWP and HWAE, respectively. EC₅₀ values of reducing power were 7.6 ± 0.1, 7.9 ± 0.0 and 12.5 ± 0.1 mg/mL, whereas those of the chelating abilities on ferrous ions were 3.1 ± 0.0, 4.6 ± 0.1 and 4.9 ± 0.1 mg/mL. The EC₅₀ values of the antioxidant activity, of the DPPH scavenging, and of the reducing power were correlated with total polysaccharide as well as with total phenol content. The antioxidant activities of all the extracts may be caused by both polysaccharides and polyphenols or by a complex of both.     

Loss of swiss cheese in Neurons Contributes to Neurodegeneration with Mitochondria Abnormalities,Reactive Oxygen Species Acceleration and Accumulation of Lipid Droplets in Drosophila Brain

Various neurodegenerative disorders are associated with human NTE/PNPLA6 dysfunction. Mechanisms of neuropathogenesis in these diseases are far from clearly elucidated. Hereditary spastic paraplegia belongs to a type of neurodegeneration associated with NTE/PNLPLA6 and is implicated in neuron death. In this study, we used Drosophila melanogaster to investigate the consequences of neuronal knockdown of swiss cheese (sws)—the evolutionarily conserved ortholog of human NTE/PNPLA6—in vivo. Adult flies with the knockdown show longevity decline, locomotor and memory deficits, severe neurodegeneration progression in the brain, reactive oxygen species level acceleration, mitochondria abnormalities and lipid droplet accumulation. Our results suggest that SWS/NTE/PNPLA6 dysfunction in neurons induces oxidative stress and lipid metabolism alterations, involving mitochondria dynamics and lipid droplet turnover in neurodegeneration pathogenesis. We propose that there is a complex mechanism in neurological diseases such as hereditary spastic paraplegia, which includes a stress reaction, engaging mitochondria, lipid droplets and endoplasmic reticulum interplay.