东北虎中五个Sox基因的保守区序列分析(英文)

在哺乳动物中,Y染色体决定着雄性性别,这是由于在其短臂上存在一个编码睾丸决定因子 (TDF) 的基因。1990年,人们克隆了睾丸决定因子基因并命名为SRY。序列分析表明SRY基因中存在一个保守区,与染色体高迁移率组 (HMG) 蛋白质上的DNA结合结构域具有一定的相似性。基于HMG基序的保守性人们发现了一个新的基因家族Sox基因家族。凡是在HMG区域与SRY基因具有50%以上相似性的基因被称为Sox基因。Sox基因在早期胚胎发育过程中参与多种发育途径,具有重要的作用。参与诸如性别决定、骨组织的发育、血细胞生成过程、神经系统的发育、晶状体的发育等多种早期胚胎发育过程。 虎(Panthera tigris)作为世界上最濒危的兽类之一,东北虎(Panthera tigris altaica Temminck)是其中的一个亚种,被列为一类珍稀动物。本文对其发育基因家族—SOX基因进行了研究。 利用肌肉组织为材料制备基因组DNA, 应用特异于HMG-box区域的兼并引物, 扩增了东北虎的SOX基因。在扩增产物中发现一条220bp的扩增带。经过克隆与序列测定和同源性检索,发现5个基因片段(Fig.1&2)。其与人SRY基因的相似性分别为75%、56%、51%、67% 和48%;与小鼠Sry基因的相似性分别为73%、54%、57%、66% 和 48% (Table 1)。因此这5个DNA片段为东北虎的5个Sox基因片     

Assessment of chromium species dynamics in root solutions using isotope tracers

BackgroundChromium (Cr) exists in the environment in two chemical forms; Cr^III is an essential micronutrient for glucose and lipid metabolism, whereas Cr^VI is toxic and a recognised carcinogen through inhalation. Numerous studies have attempted to evaluate their transfer mechanisms from soil and solution media into plants, usually with respect to the hyperaccumulation, detoxification and tolerance of the plant to Cr^VI.MethodsIsotopically enriched species of Cr, added as ⁵⁰Cr^III and ⁵³Cr^VI, were used to investigate transfer from solution into the root systems of Spinacia oleracea. In addition the effect of sulphate (SO₄²⁻), as a competitor for Cr^VI uptake, was investigated. Separation of ⁵⁰Cr^III and ⁵³Cr^VI was undertaken using HPLC-ICP-QQQ following isolation of root solutions using freeze/thaw centrifugation.ResultsIrrespective of supplied Cr^VI concentration (250, 500 or 1000 μg L⁻¹), the dominant species in both apoplastic (routed through cell wall and intercellular space as a passive mechanism) and symplastic (routed through cytoplasm as an active mechanism) root solutions was Cr^III. There was evidence for Cr^VI reduction in the rhizosphere prior to uptake as an additional detoxification mechanism. Sulphate promoted uptake of Cr^VI through the active pathway, although increases in SO₄^2- concentration did not yield a proportional increase in Cr symplastic solution concentration; Cr^III was also the dominant species in these root solutions.ConclusionThe results indicate that Spinacia oleracea plants can effectively reduce Cr^VI to Cr^III and that the uptake pathways for both Cr^III and Cr^VI are more complex than previously reported. Further work is required to understand the physiological processes that result in the reduction of Cr^VI prior to, and during, uptake. The efficacy of sulphate to augment existing agricultural management strategies, such as liming and organic reincorporation, also requires further investigation to establish suitable application rates and applicability to other environmental contaminants.     

In-depth characterization of the GOTCAB saponins in seven cultivated Gypsophila L. species (Caryophyllaceae) by liquid chromatography coupled with quadrupole-Orbitrap mass spectrometer

Roots of Gypsophila L. (Caryophyllaceae) have been shown to accumulate bidesmosides of triterpenoid carboxylic acids, also called GOTCAB saponins (Glucuronide Oleanane-type Triterpenoid Carboxylic Acid 3, 28-Bidesmosides). The study aimed at in-depth characterization of GOTCABs from root extracts of cultivated Gypsophila scorzonerifolia Ser., G. acutifolia Stev. ex Spreng., G. altissima L., G. pacifica Kom., G. paniculata L., G. oldhamiana Miq. and G. zhegualensis Krasnova using ultra high-performance liquid chromatography coupled with hybrid quadrupol-Orbitrap high resolution mass spectrometry (UHPLC-HRMS). Based on the accurate mass measurements, elemental composition, isotopic peak profiles, fragmentation pattern in tandem mass spectrometry (MS/MS) and literature data, a total of 53 GOTCABs were tentatively identified. In addition, 29 core structures, forming between 2 and 12 isobaric isomers were described. They possess gypsogenin, quillaic and gypsogenic acid as sapogenin, substituted at C-3 with O-β-d-galactopyranosyl-(1 → 2)-[pentosyl-(1 → 3)]-β-d-glucuronopyranoside (β-chain). According to the C-28 ester-bonded oligosaccharide (α-chain) saponins were classified into four groups: GOTCABs with C-28 tetra- and pentasaccharide (type I), GOTCABs with C-28 oligosaccharide substituted with methoxycinnamoyl group (type II), GOTCABs with mono- and diacetylated C-28 oligosaccharide (type III) and GOTCABs with C-28 oligosaccharide substituted with both acetyl and methoxycinamoyl groups (type IV). The possible fragmentation pathways of saponins were proposed. Eleven core structures forming between 2 and 7 isobars are undescribed in the literature. To examine the differences between the assayed Gypsophila species at the same environmental conditions, the variation of saponins was estimated by hierarchical clustering on isobaric fingerprints of GOTCABs. The clustering of the studied species revealed three well-defined clusters. The first cluster comprises G. scorzonerifolia (G1) and G. altissima (G3), characterized by GOTCABs from type III. G. acutifolia (G2) and G. pacifica (G4) formed the second cluster accumulating saponins from types II and III. The third cluster grouped G. paniculata (G5), G. oldhamiana (G6) and G. zhegualensis (G7) sharing GOTCABs from types IV in addition to II and III. This is the first report on the saponins from G. scorzonerifolia and G. zhegualensis. An in-depth depiction of the GOTCAB saponin composition of seven cultivated Gypsophila species was achieved. Therefore, saponins are worth investigating for better understanding of the potential use of Gypsophila roots for pharmaceutical purposes.     

Zinc-aggravated M1 microglia regulate astrocytic engulfment via P2×7 receptors

BackgroundGlial cells such as astrocytes and microglia play an important role in the central nervous system via communication between these glial cells. Activated microglia can exhibit either the inflammatory M1 phenotype or the anti-inflammatory M2 phenotype, which influences astrocytic neuroprotective functions, including engulfment of cell debris. Recently, extracellular zinc has been shown to promote the inflammatory M1 phenotype in microglia through intracellular zinc accumulation and reactive oxygen species (ROS) generation.PurposeHere, we investigated whether the zinc-enhanced inflammatory M1 phenotype of microglia affects the astrocytic engulfing activity.MethodsEngulfing activity was assessed in astrocytes treated with microglial-conditioned medium (MCM) from lipopolysaccharide (LPS)-activated or from ZnCl₂-pretreated LPS-activated M1 microglia. The effect of zinc on microglia phenotype was also validated using the zinc chelator N,N,N’,N’-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) and the ROS scavenger Trolox.ResultsAlthough treatment of astrocytes with LPS showed no significant effect on the engulfing activity, MCM from LPS-induced M1 microglia increased the beads uptake by astrocytes. This increased uptake activity was suppressed when MCM from LPS-induced M1 microglia pretreated with ZnCl₂ was applied to astrocytes, which was further abolished by the intracellular zinc chelator TPEN and the ROS scavenger Trolox. In addition, expression of P2×7 receptors (P2×7R) was increased in astrocytes treated with MCM derived from M1 microglia but not in the M1 microglia pretreated with ZnCl₂.ConclusionThese findings suggest that zinc pre-treatment abolishes the ability of LPS-induced M1 microglia to increase the engulfing activity in astrocytes via alteration of astrocytic P2×7R.     

Reductive activation of mitomycins A and C by vitamin C

The anticancer drug mitomycin C produces cytotoxic effects after being converted to a highly reactive bis-electrophile by a reductive activation, a reaction that a number of 1-electron or 2-electron oxidoreductase enzymes can perform in cells. Several reports in the literature indicate that ascorbic acid can modulate the cytotoxic effects of mitomycin C, either potentiating or inhibiting its effects. As ascorbic acid is a reducing agent that is known to be able to reduce quinones, it could be possible that the observed modulatory effects are a consequence of a direct redox reduction between mitomycin C and ascorbate. To determine if this is the case, the reaction between mitomycin C and ascorbate was studied using UV/Vis spectroscopy and LC/MS. We also studied the reaction of ascorbate with mitomycin A, a highly toxic member of the mitomycin family with a higher redox potential than mitomycin C. We found that ascorbate is capable to reduce mitomycin A efficiently, but it reduces mitomycin C rather inefficiently. The mechanisms of activation have been elucidated based on the kinetics of the reduction and on the analysis of the mitosene derivatives formed after the reaction. We found that the activation occurs by the interplay of three different mechanisms that contribute differently, depending on the pH of the reaction. As the reduction of mitomycin C by ascorbate is rather inefficiently at physiologically relevant pH values we conclude that the modulatory effect of ascorbate on the cytotoxicity of mitomycin C is not the result of a direct redox reaction and therefore this modulation must be the consequence of other biochemical mechanisms.     

Analyses of landuse change impacts on catchment runoff using different time indicators based on SWAT model

Previous researches mainly focused on the runoff responses to landuse change based on annual, seasonal or monthly time scales, there are few studies based on daily scale. We conducted a comprehensive investigation into runoff responses on the daily scale as well as annual and monthly time scales using SWAT, and compared the impacts of time scales with different time indicators quantitatively. Jinjiang, a coastal catchment of southeast China with a humid sub-tropical climate, was used for simulations. A calibrated SWAT model produced satisfactory reproduction of annual, monthly and daily runoff processes over a nine-year (2002–2010) period at three gauging stations. Runoff was then simulated and compared using the same meteorological input but two different landuse scenarios (1985 and 2006, with reduced forest and increased cropland and urbanized area). The results showed varying change in runoff among three time scales and three catchments. The annual runoff had the smallest increase between two scenarios, monthly runoffs had medium rates (increasing in all months except October–November), and daily runoff had the largest rates with the increase in flood peaks but decrease in drought flows, because of the variable influence on interception/evapotranspiration loss, percolation and antecedent soil water storage. Indicators of different time scales (annual runoff, monthly runoff, maximum 1-day and 5-day flood runoff, minimum 1-day and 7-day runoff) proved appropriate for analysing landuse change impacts.