微波萃取苦荞壳中总黄酮工艺研究

本文在提取苦荞壳中总黄酮的工艺实验中,优化了提取溶剂的种类,水和乙醇,同时还使用了超声波和微波辅助提取,并分别将不同因素,如溶剂种类及浓度,提取时间,温度,pH,液固比等,对提取结果的影响作了比较,结果表明,当介质为乙醇时的微波萃取效果明显优于其他提取方法。     

几种不同碳、氮源对隐甲藻生长及二十二碳六烯酸产量的影响

目的：找出有利于隐甲藻生长和二十二碳六烯酸（DHA）积累的碳、氮源。方法：利用不同碳、氮源培养隐甲藻,收集藻体后提取脂肪酸并甲酯化,然后利用毛细管气相色谱法进行分析。结果：最适的单一碳、氮源分别为葡萄糖、酵母粉,在此培养条件下隐甲藻培养72h后的生物量（干重）和DHA产量分别为3．90和0．642g／L。结论：葡萄糖、酵母粉分别作为碳、氮源时更有利于隐甲藻的生长和DHA的积累。     

Colloidal stability of carbon nanotubes in an aqueous dispersion of phospholipid

Within the family of nanomaterials, carbon nanotubes (CNTs) have emerged as a new efficient scaffold for studying molecular interactions at interfaces. Poor dispersability of CNTs in any solvent presents a considerable drawback for the development of novel functional composite structures. Previous studies have demonstrated that the solubility of CNTs can be greatly enhanced by employing appropriate surfactants, some of them being biological molecules. In this work, we study the noncovalent wrapping of lipid chains onto the graphitic surface of single-walled material (SWCNTs) by electron microscopy and Raman spectroscopy. Stable and homogenous aqueous suspensions of SWCNTs in the presence of lipids have been prepared, whereas their electrophoretic mobility was confirmed by zeta-potential measurements. Raman measurements revealed that smaller diameter SWCNTs are preferentially dispersed by lipid molecules in the aqueous supernatant part of the prepared suspension.     

An Overview of the Development,Status, and Application of Equilibrium Partitioning Sediment Benchmarks for PAH Mixtures

This article provides an overview of the development, theoretical basis, regulatory status, and application of the U.S. Environmental Protection Agency's (USEPA's) Equilibrium Partitioning Sediment Benchmarks (ESBs) for PAH mixtures. ESBs are compared to other sediment quality guidelines (SQGs) for PAHs. Data that examine the ability of the ESB approach to predict toxic effects to invertebrates are discussed. A USEPA draft methodology for the development of site-specific ESBs that takes into account the limited bioavailability of PAHs at certain sites is discussed. Research is presented that compares the ability of ESBs and site-specific ESBs to predict the toxicity of sediments collected from manufactured gas plants (MGPs). Site-specific ESBs that accounted for adsorption of PAHs onto black carbon were better predictors of the toxicity of sediments from MGP sites than ESBs that did not account for adsorption to black carbon.     

Effect of imitated global warming on Δ<Superscript>13</Superscript>C values in seven plant species growing in tibet alpine meadows

Open-top chambers were used to estimate the possible effects of global warming on δ¹³C of seven plant species grown in alpine meadow ecosystem. The δ¹³C values of plant species were lower after long-term growth in open-top chambers. In the course of experiment, temperature significantly increased inside the chambers by 4°C. Plant species grown at a lower elevation above sea level had higher δ¹³C values as compared to those grown at a higher elevation. This was in accordance with the effect of open-top chamber on δ¹³C values in plants. Greater availability of CO₂ and lower water vapor pressure at higher temperature inside the chambers, as indicated by an increase in discrimination against ¹³CO₂, probably result in more negative δ¹³C values of plants because higher stomatal conductance increases availability of CO₂ and causes greater discrimination against ¹³CO₂. The plant species studied could be the indicator species for testing global warming by the change in carbon isotope ratios at the two growth temperatures. This text was submitted by the authors in English.     

Beneficial effects of dithiothreitol on relative levels of glutathione S-transferase activity and thiols in oocytes, and cell number, DNA fragmentation and allocation at the blastocyst stage in the mouse

We analyzed the effect of in vitro aging of mouse oocytes in the presence of dithiothreitol (DTT) on relative levels of glutathione S-transferase (GST) activity and thiols in oocytes, and cell number, DNA fragmentation and cellular allocation to the inner cell mass (ICM) and trophectoderm (TE) lineage at the blastocyst stage. Ovulated oocytes from gonadotropin primed hybrid female mice of 6-8 weeks of age were aged in vitro in the presence of 0, 5, 50, or 500 microM DTT for 6 hr prior to insemination. Relative levels of GST activity and thiols in oocytes were determined by confocal laser scanning microscopy, DNA fragmentation using a single-step TUNEL method, and cell allocation to the ICM and TE lineage by blastocyst staining with propidium iodide and Hoechst 33258. Non-aged oocytes exhibited higher relative levels of GST activity and thiols when compared to oocytes aged in the presence of 0, 5, and 50 microM DTT. Day 5 blastocysts from the 5, 50, and 500 microM DTT groups exhibited higher total number of cells, number of ICM cells, and ICM/TE ratio, but lower percentage of number of nuclei with DNA fragmentation/number of ICM cells than blastocyst from the 0 microM DTT group. These data show that DTT counteracts the negative effects of a post-ovulatory aging of mouse oocytes in vitro on relative levels of GST activity and thiols in oocytes, and percentage of number of nuclei with DNA fragmentation/number of ICM cells, total number of cells, number of ICM cells and ICM/TE ratio in Day 5 blastocysts.     

Microarray-based analysis of changes in diversity of microbial genes involved in organic carbon decomposition following land use/cover changes

To increase our understanding of the impact of land use/cover changes on soil microbial decomposition genes involved in organic carbon decomposition, we analyzed soil samples in four sites with different land cover/use histories in a subalpine region of western Sichuan. One site was in a primitive Abies faxoniana forest, the second and the third sites were spruce plantations established in 1960's and 1980's, respectively, and the fourth site was in a cropland dating back to 1960's. The genomic DNA from the microbial community was isolated and hybridized against a functional gene microarray containing 1,961 probes. There were 39, 62, 41, and 28 gene probes with statistically significant positive signals and the gene diversity index (H') values were 3.59, 4.04, 3.70 and 3.16 in primitive forest, spruce plantations established in 1960s and 1980s and cropland, respectively. The results suggested that the number of functional genes and the gene diversity index were correlated with increasing amounts of soil organic carbon, except in the primitive Abies faxoniana forest site. cluster analysis demonstrated that primitive forest soil was clustered more closely to soil from the spruce plantation established in 1960s.     

Factors influencing the distribution of Subantarctic deep-sea benthic foraminifera,Campbell and Bounty Plateaux,New Zealand

We investigate the combination of environmental factors that influence the distribution patterns of benthic foraminiferal tests (> 63 μm) in a topographically varied region crossed by both the Subtropical and Subantarctic Fronts, south-east of New Zealand. Seafloor sample sites, extending from outer shelf (50 m) to abyssal (5000 m) depths, are bathed by five different water masses, and receive phytodetritus from Subtropical, Subantarctic and Circumpolar surface water masses. Eight mappable associations are recognised by Q-mode cluster analysis of the benthic foraminiferal census data. Similar associations are identified using cluster analysis based solely on the presence or absence of species. Canonical correspondence analysis and a correlation coefficient matrix were used to relate the faunal data to a set of environmental proxies. These show that factors related to water depth (especially decreasing food supply with increasing depth) are the most significant in determining the overall foraminiferal distribution. Other contributing factors include surface water productivity and its seasonality; bottom water ventilation; energetic state of the benthic boundary layer and resulting substrate texture; and bottom water carbonate corrosiveness. Three shallow-water associations (50–700 m), dominated by Cassidulina carinata, Trifarina angulosa, Globocassidulina canalisuturata, Gavelinopsis praegeri, and Bolivina robusta, occur in coarse substrates on the continental shelf, and on the crests and upper slopes of four seamounts under well-oxygenated, high energy regimes, and high food input. Three mid bathyal to upper abyssal associations (500–3300 m), dominated by Alabaminella weddellensis, C. carinata, and Epistominella exigua, occur in biopelagic sandy mud, beneath a region of strongly seasonal food supply, with their composition influenced by total food flux, ventilation (Oxygen Minimum Zone), and bottom current strength. An unusual lower bathyal association (1200–2100 m), dominated by T. angulosa and Ehrenbergina glabra, occurs in a belt of coarser sandy substrate that runs along the crest of the submarine plateaux slopes beneath the strongly-flowing Subantarctic Front-related currents. A deep abyssal association (3500–5000 m), dominated by Nuttallides umbonifer and Globocassidulina subglobosa, occurs on the abyssal plain beneath oligotrophic lower Circumpolar Water south-east of the Subantarctic Front and is strongly influenced by the cold, carbonate-corrosive conditions.     

Carbon Monoxide Promotes Lateral Root Formation in Rapeseed

Carbon monoxide (CO), an odorless, tasteless and colorless gas, has recently proved to be an important bioactive or signalmolecule in mammalian cells, with its effects mediated mainly by nitric oxide (NO). In the present report, we show thatexogenous CO induces lateral root (LR) formation, an NO-dependent process. Administration of the CO donor hematin torapeseed (Brassica napus L. Yangyou 6) seedlings for 3 days, dose-dependently promoted the total length and number ofLRs. These responses were also seen following the application of gaseous CO aqueous solutions of different saturatedconcentrations. Furthermore, the actions of CO on seedlings were fully reversed when the CO scavenger hemoglobin (Hb)or the CO-specific synthetic inhibitor zinc protoporphyrin-IX (ZnPPIX) were added. Interestingly, depletion of endogenousNO using its specific scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide potassium salt (cPTIO)or the nitric oxide synthase (NOS) inhibitor N~G-nitro-L-arginine methyl ester (L-NAME),led to the complete abolition ofLR development, illustrating an important role for endogenous NO in the action of CO on LR formation. However, theinduction of LR development by 200 umol/L sodium nitroprusside (SNP),an NO donor, was not affected by the presenceor absence of ZnPPIX. Furthermore, using an anatomical approach combined with laser scanning confocal microscopywith the NO-specific fluorophore 4,5-diaminofluorescein diacetate, we observed that both hematin and SNP increased NOrelease compared with control samples and that the NO signal was mainly distributed in the LR primordia (LRP), especiallyafter 36 h treatment. The LRP were found to have similar morphology in control, SNP-and hematin-treated seedlings.Similarly, the enhancement of the NO signal by CO at 36 h was differentially quenched by the addition of cPTIO, L-NAME,ZnPPIX and Hb. In contrast, the induction of NO caused by SNP was not affected by the application of ZnPPIX. Therefore,we further deduced that CO induces LR formation probably mediated by the NO/NOS pathway and NO may act downstreamof CO signaling, which has also been shown to occur in animals.     

Microclimatic Conditions Regulate Surface Activity in Harvester Ants <Emphasis Type="Italic">Messor barbarus</Emphasis>

This paper analyses the effect of microclimatic factors (internal soil temperature, surface temperature and surface relative humidity) on surface activity of Messor barbarus harvester ants. We selected 44 colonies in an area of Mediterranean grassland near Madrid (Central Spain), which were monitored for activity between March 1998 and September 1999. Results indicate that microclimatic factors are good predictors of colony activation and intensity of activity. Colonies became active above certain critical values of internal soil temperature and relative humidity. For active colonies, surface temperature was the main regulatory factor for worker departure rate, which peaked at around 25–30°C. Worker speed was positively correlated with surface temperature, although the relationship was weaker for large-sized workers. Microclimatic factors were not enough, however, to predict task allocation outside the nest. The explanation for this aspect of ant behavior probably requires the inclusion of biotic factors in the models.