繖序臭黄荆营养成分分析

对野生植物繖序臭黄荆的营养成分进行了分析,结果表明,繖序臭黄荆中含有多种营养成分,丰富的矿质元素和维生素以及β-胡萝卜素。繖序臭黄荆中至少含有17种氨基酸。旨在为开发利用繖序臭黄荆的植物资源提供科学依据。     

Key Amino Acid Residues Involved in Multi-Point Binding Interactions between Brazzein, a Sweet Protein, and the T1R2-T1R3 Human Sweet Receptor

The sweet protein brazzein [recombinant protein with sequence identical with the native protein lacking the N-terminal pyroglutamate (the numbering system used has Asp2 as the N-terminal residue)] activates the human sweet receptor, a heterodimeric G-protein-coupled receptor composed of subunits Taste type 1 Receptor 2 (T1R2) and Taste type 1 Receptor 3 (T1R3). In order to elucidate the key amino acid(s) responsible for this interaction, we mutated residues in brazzein and each of the two subunits of the receptor. The effects of brazzein mutations were assayed by a human taste panel and by an in vitro assay involving receptor subunits expressed recombinantly in human embryonic kidney cells; the effects of the receptor mutations were assayed by in vitro assay. We mutated surface residues of brazzein at three putative interaction sites: site 1 (Loop43), site 2 (N- and C-termini and adjacent Glu36, Loop33), and site 3 (Loop9-19). Basic residues in site 1 and acidic residues in site 2 were essential for positive responses from each assay. Mutation of Y39A (site 1) greatly reduced positive responses. A bulky side chain at position 54 (site 2), rather than a side chain with hydrogen-bonding potential, was required for positive responses, as was the presence of the native disulfide bond in Loop9-19 (site 3). Results from mutagenesis and chimeras of the receptor indicated that brazzein interacts with both T1R2 and T1R3 and that the Venus flytrap module of T1R2 is important for brazzein agonism. With one exception, all mutations of receptor residues at putative interaction sites predicted by wedge models failed to yield the expected decrease in brazzein response. The exception, hT1R2 (human T1R2 subunit of the sweet receptor):R217A/hT1R3 (human T1R3 subunit of the sweet receptor), which contained a substitution in lobe 2 at the interface between the two subunits, exhibited a small selective decrease in brazzein activity. However, because the mutation was found to increase the positive cooperativity of binding by multiple ligands proposed to bind both T1R subunits (brazzein, monellin, and sucralose) but not those that bind to a single subunit (neotame and cyclamate), we suggest that this site is involved in subunit-subunit interaction rather than in direct brazzein binding. Results from this study support a multi-point interaction between brazzein and the sweet receptor by some mechanism other than the proposed wedge models.     

Behavioral patterns of two fiddler crab species Uca rapax and Uca tangeri in a seminatural mangrove system

Zoos increasingly transform their exhibitions from traditional one‐species enclosures to more natural exhibits, that is, environments that capture part of an ecosystem including a selection of animals and plants that occur there. Thus, enhancing the experience of its human visitors while also allowing its residents to possibly show more natural behavior. In 2017 Royal Burger's Zoo (Arnhem, The Netherlands) created and opened a mangrove‐like environment containing fiddler crabs. Fiddler crabs display a broad range of behaviors, and this research examines which wild‐type behavior and behavioral patterns can be observed on a seminatural mudflat. The behavior shown by Uca rapax and Uca tangeri on the mudflat was counted each hour between 07:00 and 17:00. An asymmetric tidal regime was present in the enclosure including two high water periods. Various known fiddler crab behaviors, including waving and combat, were observed but no copulation. A clear pattern in exposed crabs on the mudflat was found, with low numbers visible in the early morning and the highest numbers present in the early afternoon, while number of visitors did not have a significant effect on this pattern. Interestingly, the highest abundances were not observed around the ebbing tide (07:00–09:00), as observed in the wild, but somewhat later, possibly due to the asymmetric tidal scheme or the interaction of tidal and daily rhythms. This study shows that in captivity, fiddler crabs indeed show a range of natural behaviors which is linked to the tidal and possibly daily rhythm as well.     

A comparative histological study between normal and fasciated shoots of <Emphasis Type="Italic">Prunus avium</Emphasis> generated <Emphasis Type="Italic">in vitro</Emphasis>

A combination of Murashige and Skoogs medium and N⁶–benzyladenine (BA) at various concentrations (0, 0.1, 0.25, 0.5, 0.75, 1.0, 1.25 and 1.5 mg l^–1) was supplied to shoot tips from root cuttings of a 50-year-old wild-cherry tree (Prunus avium). The concentration of BA in the growing medium was a determining factor with respect to the number of proliferated shoots per explant in vitro.Normal and fasciated shoots were generated when BA was present at 0.5, 0.75, 1.0 and 1.25 mg l^–1 in the medium and the mean numbers of normal shoots per explant were 3.63, 5.37, 8.93 and 7.30 respectively, and those of the fasciated shoots per explant were 0.03, 0.1, 0.47 and 0.4 respectively. Anatomical analysis by confocal microscopy of sections of paraffin-embedded specimens revealed that the cell structure and organization of the cortex and vascular cylinder in the fasciated shoots was similar to that in normal shoots. However, the cross-sectional area of stem of the fasciations was apparently greater than that of the normal shoots. In particular, the volume of vascular tissues, of pith and of some individual parenchyma cells in the cortex and pith was apparently greater in fasciated shoots than in normal shoots. Increases in cytokinesis and morphogenetic activity, such as the development of callus-like regions and the formation of adventitious shoots, were observed in the cortex and pith throughout the fasciations. The fasciated shoots had numerous buds and initiating new shoots at their apices while normal shoots had a single dominant axial bud.     

Medicago truncatula stress associated protein 1 gene (MtSAP1) overexpression confers tolerance to abiotic stress and impacts proline accumulation in transgenic tobacco

Stress associated proteins (SAP) have been already reported to play a role in tolerance acquisition of some abiotic stresses. In the present study, the role of MtSAP1 (Medicago truncatula) in tolerance to temperature, osmotic and salt stresses has been studied in tobacco transgenic seedlings. Compared to wild type, MtSAP1 overexpressors were less affected in their growth and development under all tested stress conditions. These results confirm that MtSAP1 is involved in the response processes to various abiotic constraints. In parallel, we have performed studies on an eventual link between MtSAP1 overexpression and proline, a major player in stress response. In an interesting way, the results for the transgenic lines did not show any increase of proline content under osmotic and salt stress, contrary to the WT which usually accumulated proline in response to stress. These data strongly suggest that MtSAP1 is not involved in signaling pathway responsible for the proline accumulation in stress conditions. This could be due to the fact that the overexpression of MtSAP1 provides sufficient tolerance to seedlings to cope with stress without requiring the free proline action. Beyond that, the processes by which the MtSAP1 overexpression lead to the suppression of proline accumulation will be discussed in relation with data from our previous study involving nitric oxide.     

Lipidome and proteome of lipid droplets from the methylotrophic yeast Pichia pastoris

Lipid droplets (LD) are the main depot of non-polar lipids in all eukaryotic cells. In the present study we describe isolation and characterization of LD from the industrial yeast Pichia pastoris. We designed and adapted an isolation procedure which allowed us to obtain this subcellular fraction at high purity as judged by quality control using appropriate marker proteins. Components of P. pastoris LD were characterized by conventional biochemical methods of lipid and protein analysis, but also by a lipidome and proteome approach. Our results show several distinct features of LD from P. pastoris especially in comparison to Saccharomyces cerevisiae. P. pastoris LD are characterized by their high preponderance of triacylglycerols over steryl esters in the core of the organelle, the high degree of fatty acid (poly)unsaturation and the high amount of ergosterol precursors. The high phosphatidylinositol to phosphatidylserine of ~ 7.5 ratio on the surface membrane of LD is noteworthy. Proteome analysis revealed equipment of the organelle with a small but typical set of proteins which includes enzymes of sterol biosynthesis, fatty acid activation, phosphatidic acid synthesis and non-polar lipid hydrolysis. These results are the basis for a better understanding of P. pastoris lipid metabolism and lipid storage and may be helpful for manipulating cell biological and/or biotechnological processes in this yeast.     

Supercritical Carbon Dioxide Extraction of Allium ursinum: Impact of Temperature and Pressure on the Extracts Chemical Profile

The aim of this study was to extract Allium ursinum L. for the first time by supercritical carbon dioxide (SC−CO₂) as green sustainable method. The impact of temperature in the range from 40 to 60 °C and pressure between 150 and 400 bar on the quality of the obtained extracts and efficiency of the extraction was investigated. The highest extraction yield (3.43 %) was achieved by applying the extraction conditions of 400 bar and 60 °C. The analysis of the extracts was performed by gas chromatography and mass spectrometry (GC/MS). The most dominant sulfur-containing constituent of the extracts was allyl methyl trisulfide with the highest abundance at 350 bar and 50 °C. In addition, the presence of other pharmacologically potent sulfur compounds was recorded including S-methyl methanethiosulfinate, diallyl trisulfide, S-methyl methylthiosulfonate, and dimethyl trisulfide. Multivariate data analysis tool was utilized to investigate distributions of the identified compounds among the extracts obtained under various extraction conditions and yields. It was determined that the SC−CO₂ extraction can by efficiently used for A. ursinum.     

Prevalence of multidrug resistance in Pseudomonas spp. isolated from wild bird feces in an urban aquatic environment

Antimicrobial resistance (AMR) has been detected in the microbiota of wildlife, yet little is known about the origin and impact within the ecosystem. Due to the shortage of nonepizootic surveillance, there is limited understanding of the natural prevalence and circulation of AMR bacteria in the wild animal population, including avian species. In this surveillance study, feces from wild birds in proximity to the River Cam, Cambridge, England, were collected and Pseudomonas spp. were isolated. Of the 115 samples collected, 24 (20.9%; 95% CI, 12.6%‒29.2%) harbored Pseudomonas spp. of which 18 (75%; 95% CI, 58%‒92%) had a multiple antibiotic resistance (MAR) index greater than 0.2. No Pseudomonas spp. isolate in this study was pansusceptible. Resistance was found among the 24 isolates against ciprofloxacin (87.5%; 95% CI, 74.3%‒100%) and cefepime (83.3%; 95% CI, 68.4%‒98.2%), both of which are extensively used to treat opportunistic Pseudomonas spp. infections. The prevalence of Pseudomonas spp. in the wild bird feces sampled during this study is greater than previous, similar studies. Additionally, their multidrug resistance profile provides insight into the potential risk for ecosystem contamination. It further highlights the importance of a One Health approach, including ongoing surveillance efforts that help to develop the understanding of how wildlife, including avifauna, may contribute and disperse AMR across the ecosystem.     

盐胁迫下不同基因型番茄可溶性物质含量的变化

以两种野生番茄秘鲁番茄(Lycopersicon peruvianum LAlll)、潘那利番茄(Lycopersicon pennellii LA716)和两种栽培番茄"鲜丰98-7"、"交农1号"为材料,用NaCl 150 mmol/L进行盐胁迫,测定及分析了植株体内Na 、K 、Ca2 等无机离子和某些有机溶质游离脯氨酸、可溶性糖的含量.结果表明,盐胁迫条件下,野生番茄在新叶中积累了大量的Na 等无机离子,而栽培番茄新叶内脯氨酸和可溶性糖的含量却显著提高,且它具有将吸收的Na 区域化到老叶中的能力.说明野生番茄和栽培番茄在可溶性物质的合成和积累能力上有明显差异,它们是通过不同代谢途径和机理来适应盐环境的.