首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 93 毫秒
1.
Using a combination of high-performance ion chromatography analysis and kinetic studies, the pathway of dephosphorylation of myo-inositol hexakisphosphate by the phytases purified from faba bean and lupine seeds, respectively, was established. The data demonstrate that the legume seed phytases under investigation dephosphorylate myo-inositol hexakisphosphate in a stereospecific way. The phytase from faba bean seeds and the phytase LP2 from lupine seeds degrade phytate by sequential removal of phosphate groups via D-Ins(1,2,3,5,6)P(5), D-Ins(1,2,5,6)P(4), D-Ins(1,2,6)P(3), and D-Ins(1,2)P(2) to finally Ins(2)P, whereas the phytases LP11 and LP12 from lupine seeds generate the final degradation product Ins(2)P via D-Ins(1,2,4,5,6)P(5), D-Ins(1,2,5,6)P(4), D-Ins(1,2,6)P(3), and D-Ins(1,2)P(2).  相似文献   

2.
By using Particle-Induced X-ray Emission (PIXE) technique, the effect of arsenic (As) on the mineral contents and translocation in the xylem of rice (Oryza sativa L. cv. ‘Akihikari’) was studied. The results suggest that exogenous As increased the concentrations of phosphorus (P), calcium (Ca) magnesium (Mg), sulfur (S), and manganese (Mn) in xylem, while the concentrations of potassium (K) remained unchanged. The highest concentration of As to the rice roots did not have any clear effect on the translocation of P, Ca, S, and chlorine (Cl) in the xylem, indicating that the increasing concentrations of the minerals may be due to a condensation effect, resulting from the repression of water movement in xylem by As-toxicity. Among the metal micronutrients, As decreased the concentrations and translocations of iron (Fe), zinc (Zn), and copper (Cu).  相似文献   

3.
The methanol extract of sesame (Sesamum indicum) seeds was fractionated and purified with the assistance of conventional column chromatography to afford 29 compounds including seven furofuran lignans. Among these isolates, (+)-samin (1) was obtained from the natural source for the first time. In addition, (-)-asarinin (30) and sesamol (31) were generated by oxidative derivation from (+)-sesamolin (2) and (+)-sesamin (3), two abundant lignans found in sesame seeds. To evaluate their in vitro antioxidant potential, the seven isolated lignans (1-7) and the two derivatives (30 and 31) were examined for the scavenging activities on DPPH free radicals and superoxide anions. Moreover, the capability of chelating ferrous ions and reducing power of these sesame lignans were also measured. The results suggest that, besides the well-known sesamolin and sesamin, the minor sesame lignans (+)-(7S,8'R,8R)-acuminatolide (5), (-)-piperitol (6), and (+)-pinoresinol (7) are also adequate active ingredients and may be potential sources for nutritional and pharmacological utilization.  相似文献   

4.
The resorcylic acid lactones zearalenone ( 1), alpha-zearalenol ( 2), beta-zearalenol ( 3), alpha-zearalanol (zeranol) ( 4), beta-zearalanol (taleranol) ( 5), and zearalanone ( 6) were converted to their glucuronides on a preparative scale in good yields. Reactions were conducted with bovine uridine 5'-diphosphoglucuronyl transferase (UDPGT) as catalyst and uridine 5'-diphosphoglucuronic acid (UDPGA) as cofactor. The glucuronides were isolated by column chromatography and characterized by NMR spectroscopy and mass spectrometry. Although the principal products were 4- O-glucuronides (i.e., linkage through a phenolic hydroxyl), significant quantities of the 6'- O-glucuronides (i.e., linkage through the aliphatic hydroxyl) of alcohols 2, 4, and 5 were also isolated. In the case of 3, the 2- O-glucuronide was isolated as the minor product. Overall isolated yields of glucuronides, performed on a 20-50 mg scale, were typically ca. 80% based on the resorcylic acid lactone starting material. LC-UV-MS (2) analysis of purified specimens revealed MS (2) fragmentations useful for defining the point of attachment of the glucuronide moiety to the zearalenone nucleus.  相似文献   

5.
The mineral composition of taro ( Colocasia esculenta (L.) Schott) was analyzed to develop a method to distinguish taro produced in Japan and China. The concentrations of 15 elements (Al, Ca, Cl, Mg, Mn, Br, Co, Cr, Cs, Fe, K, Na, Rb, Sc, Zn) were assayed using instrumental neutron activation analysis. The concentrations of NO(3)(-), SO(4)(2-), H(2)PO(4)(-), Cl(-), malate, and oxalate were measured by ion chromatography. The mean concentrations of H(2)PO(4)(-), Co, Cr, and Na significantly differed (P < 0.01) between taro grown in Japan and that grown in China. Discriminant analysis was performed to identify the most efficient combination of elements and compounds to discriminate the taro geographic origin. The highest percentage of correct classification was achieved with a two-variable model including H(2)PO(4)(-) and Co (100% for Japanese, 93.75% for Chinese). Principal component analysis and cluster analysis using all of the assayed elements and compounds were also conducted to determine which elements significantly accounted for the variation of the taro mineral composition. We report on the potential of H(2)PO(4)(-) and Co concentrations to differentiate taro grown in China and Japan and discuss the sources of variability in the taro mineral composition of our samples.  相似文献   

6.
Evolution of toxicity upon hydrolysis of fenoxaprop-p-ethyl   总被引:2,自引:0,他引:2  
Hydrolysis of fenoxaprop-p-ethyl (FE), a widely used herbicide, was studied in aqueous buffer solutions at pH ranging from 4.0 to 10.0. The degradation kinetics, strongly dependent on pH values, followed first-order kinetics. FE was relatively stable in neutral media, whereas it degraded rapidly with decreasing or increasing pH. In acidic conditions (pH = 4, 5), the benzoxazolyl-oxy-phenyl ether linkage of FE was cleaved to form ethyl 2-(4-hydroxyphenoxy)propanoate (EHPP) and 6-chloro-2,3-dihydrobenzoxazol-2-one (CDHB). While in basic conditions (pH = 8, 9, 10), herbicidal activity fenoxaprop-p (FA) was formed via breakdown of the ester bond of the herbicide. Both the two pathways were concurrent in neutral conditions (pH = 6, 7). Toxicity studies on Daphnia magna showed that FE was most toxic to D. magna with 48 h EC(50) of 14.3 micromol/L, followed by FA (43.8 micromol/L), CDHB (49.8 micromol/L), and EHPP (333.1 micromol/L). Mode of toxic action analysis indicated that EHPP exhibited toxicity via polar narcosis, whereas CDHB belonged to reactive acing compound. The mixture toxicity of CDHB and EHPP was nonadditive and can be predicted by a response addition model. Therefore, the evaluation of overall FE toxicity to D. magna in the aquatic systems needs to consider the degradation of FE.  相似文献   

7.
吉县蔡家川流域不同森林植被的林地水源涵养功能   总被引:10,自引:2,他引:8  
朱继鹏  王芳  高甲荣 《水土保持研究》2006,13(1):111-113,125
林地(枯落物层和土壤层)是森林植被水源涵养功能的主体,在水土保持中具有举足轻重的作用。根据蔡家川流域林地枯落物和土壤的分析与测定,研究比较了晋西黄土区不同森林植被的林地水源涵养功能。结果表明,不同植被类型枯落物的最大有效拦蓄量的大小为:虎榛子林(2.85 mm)>沙棘林(2.38 mm)>刺槐林(1.88 mm)>油松×刺槐林(1.31 mm)>油松林(0.77 mm)。不同植被类型0~60 cm土层的林地土壤最大拦蓄量为:虎榛子林(248.2 mm)>油松×刺槐林(241.0 mm)>刺槐林(210.2 mm)>草地(209.8 mm)>油松林(198.1 mm)。晋西黄土区不同森林植被的林地水源涵养功能研究,为该区水土保持林的合理经营与利用提供了科学依据。  相似文献   

8.
为研究2种紫花苜蓿(Medicagosativa L.)“阿迪娜”(耐盐基因型)和“秘鲁”(敏盐基因型)在盐胁迫处理下的生理特性与耐盐机理,采用150mmol/LNaCl胁迫处理2种紫花苜蓿幼苗,分别测定盐处理前和处理后2,4,6,8,16h的过氧化氢酶(CAT)、过氧化物酶(POD)、丙二醛(MDA)、脯氨酸(PRO)、相对含水量(RWC)和叶绿素(Chl)含量。结果表明:2种紫花苜蓿的过氧化氢酶活性、过氧化物酶活性和丙二醛含量在盐胁迫下总体呈上升趋势,脯氨酸含量和相对含水量表现出相反的趋势。叶绿素含量在盐胁迫前期稳定不变,但在胁迫后期显著性下降;2种紫花苜蓿的相对含水量和叶绿素含量的变化趋势与植株表型变化相对应。主成分分析表明,过氧化氢酶和丙二醛的贡献率最大,能更好地为苜蓿耐盐机理及分子育种研究提供理论依据。  相似文献   

9.
长寿湖水中磷形态的季节性变化特征   总被引:1,自引:0,他引:1  
为进一步了解湖泊表层水中磷形态的季节变化特征,在2009年7月(丰水期)和11月(平水期)、2010年3月(枯水期)连续监测长寿湖水中不同形态磷的含量,分析磷形态含量与水质参数之间的相关关系。结果表明,各个水期长寿湖水中的总磷(TP)都以溶解态磷(DTP)为主要存在形式,DTP在丰水期与平水期以可溶性正磷酸盐(DP)为主要存在形式,在枯水期以溶解性有机磷(DOP)为主要存在形式。总体来说,长寿湖水中TP和DTP含量呈现枯水期〉丰水期〉平水期;DP含量呈现丰水期〉平水期〉枯水期的季节变化特征。相关关系分析发现,磷形态含量与湖水的溶解氧(DO)和电导的相关性明显,与pH和高锰酸盐指数无明显的相关关系。  相似文献   

10.
氟对小鼠生精细胞凋亡的影响及锌的保护作用   总被引:1,自引:0,他引:1  
为观察氟对成年雄性小鼠生精细胞凋亡的影响及锌的保护作用,通过腹腔注射氟化钠建立氟中毒动物模型及锌保护实验。采用石蜡切片、苏木精-伊红染色(HE染色)、末端原位标记(TUNEL)及琼脂糖凝胶电泳的方法检测小鼠生精细胞的凋亡情况。结果显示:(1)氟感染组无论是低剂量组(NaF10 mg/kg)或是高剂量组(NaF 20 mg/kg)生精细胞都发生了明显的凋亡。生精细胞凋亡主要发生在精母细胞和精原细胞,凋亡指数与对照组差异极显著(P<0.05)。(2)无论是高剂量锌(ZnSO430 mg/kg)和低剂量锌(ZnSO415 mg/kg)都可以使凋亡指数明显降低,高剂量锌组的凋亡指数与对照组差异不显著(P>0.05)。  相似文献   

11.
Effect of foliar application of calcium (0.78 g, 4.68 g, and 7.8 g Ca2 +) in pre-harvest, at three different growing conditions (tunnel, mesh, and ambient), on texture and pectin in blueberries (Vaccinium corymbosum) was studied. Calcium contents in leaves as well in fruits were different (P ≤ 0.05), affected by growing conditions and time. Differences (P ≤ 0.05) in calcium content were found in tunnel cultivar fruit, during the period to cell expansion toward harvest, at calcium foliar level of 5 mL per L (7.8 g). Fruit texture was significantly higher at the beginning of the cell expansion period in the tunnel cultivar fruit, and a linear correlation between calcium concentration and texture was established. Increment in low methoxyl pectin (LMP) was influenced by growing conditions, and was different (P ≤ 0.05) for tunnel cultivar fruit. A good correlation between LMP and calcium content was obtained with the high dose of calcium (5 mL per L).  相似文献   

12.
Characterizations of lotus plumule and plumule oil, focusing on approximate composition analysis of lotus plumule powder and fatty acid composition, lipid classes, triglyceride (TG) profiles, and sterol analysis of the plumule oil, were conducted in this work. The results revealed that the lotus plumule constitutes 7.8% moisture, 4.2% ash, and 12.5% crude oil and 26.3% protein on the dry base. Lotus plumule oil is rich in linoleic acid (50.4%) and oleic acid (13.5%), and the dominating saturated fatty acids are palmitic acid (18.0%) and behenic acid (6.8%). The principal components of TG in lotus plumule oil are LLL (12.80%), beta-PLL (11.27%), beta-POL (8.28%), beta-PLO (8.58%), and beta-BeLL (8.32%). Lipid class assay of the crude oil gave the saponification value of 153.4 KOH mg/g and tocopherol content 390 mg/100 g. A distinct characteristic of lotus plumule oil is that its unsaponifiable matter is incredibly high, up to 14-19%, which consists mainly of beta-sitosterol (32%), Delta(5)-avenasterol (20%), and campesterol (6.3%). The major occurring form of sterols was found to be steryl ester. This work might be useful to develop innovative applications of lotus plumule oil.  相似文献   

13.
The feasibility of determining the nitrogen content of farmyard manure using infrared spectroscopy was investigated. Fifteen samples each of cattle, pig, and turkey manure were analyzed by three infrared techniques: Fourier transform mid-infrared (MIR), using attenuated total reflection (ATR); near-infrared reflectance (NIR-R); and near-infrared optothermal photoacoustic (NIR-OT). The near-infrared measurements were made at wavelengths determined respectively by four (NIR-OT) and five (NIR-R) band-pass filters. The total nitrogen (using the Kjeldahl method) and volatile (ammoniacal) nitrogen contents of all samples were measured by wet chemistry. Internally cross-validated (ICV) partial least-squares (PLS) regression was then used to obtain calibrations for the nitrogen content. The data sets obtained by each technique were treated separately. Within these sets, data from each manure type were treated both separately and combined: the best predictive ability was obtained by combining data from all three manure types. From the combined data set, the residual standard deviations and correlation coefficients for the ICV-predicted versus actual Kjeldahl nitrogen content were, respectively, 6772 mg/kg dry wt, 0.862 (MIR); 9434 mg/kg dry wt, 0.771 (NIR-OT); and 8943 mg/kg dry wt, 0.865 (NIR-R). For the ammoniacal nitrogen content, the residual standard deviations and correlation coefficients were 3869 mg/kg dry wt, 0.899 (MIR); 6079 mg/kg dry wt, 0.820 (NIR-OT); and 3498 mg/kg dry wt, 0.961 (NIR-R).  相似文献   

14.
利用微电极技术分别测定了2个水稻品种即武育粳3号(粳稻)和扬稻6号(籼稻)幼苗根尖细胞在吸收不同NH4+浓度(0.0250、.05、0.1、0.5、1.0和1.5.mmol/L)下膜电位的变化特征。结果表明,水稻根系吸收NH4+引起膜的去极化,去极化到一定程度出现部分复极化,有一小部分根系还有超极化现象。去极化大小随外界处理液中NH4+浓度的增加而加强,达到一定程度以后趋于平稳,吸收进程符合Michaelis-Menten动力学特征。两个品种产生的去极化程度不同,武育粳3号产生的去极化大小平均为16.5.mV,扬稻6号产生的去极化大小平均为22.6.mV。在低浓度NH4+(1.0.mmol/L)处理下,扬稻6号对NH4+较敏感,产生的去极化大小平均为17.5.mV,高于武育粳3号(去极化大小平均为10.9.mV),两个品种产生的去极化大小差异显著(p0.05)。研究结果表明,扬稻6号吸收NH4+的能力比武育粳3号强,这与吸收动力学的结果是一致的。  相似文献   

15.
The essential oils of Ocimum basilicum L., Origanum vulgare L., and Thymus vulgaris L. were analyzed by means of gas chromatography-mass spectrometry and assayed for their antioxidant and antimicrobial activities. The antioxidant activity was evaluated as a free radical scavenging capacity (RSC), together with effects on lipid peroxidation (LP). RSC was assessed measuring the scavenging activity of the essential oils on 2,2-diphenyl-1-picrylhydrazil (DPPH(*)) and OH(*) radicals. Effects on LP were evaluated following the activities of essential oils in Fe(2+)/ascorbate and Fe(2+)/H(2)O(2) systems of induction. Essential oils exhibited very strong RSCs, reducing the DPPH radical formation (IC(50)) in the range from 0.17 (oregano) to 0.39 microg/mL (basil). The essential oil of T. vulgaris exhibited the highest OH radical scavenging activity, although none of the examined essential oils reached 50% of neutralization (IC(50)). All of the tested essential oils strongly inhibited LP, induced either by Fe(2+)/ascorbate or by Fe(2+)/H(2)O(2). The antimicrobial activity was tested against 13 bacterial strains and six fungi. The most effective antibacterial activity was expressed by the essential oil of oregano, even on multiresistant strains of Pseudomonas aeruginosa and Escherichia coli. A significant rate of antifungal activity of all of the examined essential oils was also exhibited.  相似文献   

16.
Foliar application of nutrients enhances efficient use along with quick response. The experiment was undertaken to study the effect of foliar application of mineral nutrients viz., boron (B), zinc (Zn), calcium (Ca), and potassium (K) sprayed at different growth stages viz., at fruit set and at two weeks after fruit set of guava (Psidium guajava L.). Increase in plant canopy and minimum seed index was in Zn (0.03%) sprayed at fruit set. Fruit size, sugar: acid, and organoleptic score were better in K (0.5%) sprayed at two weeks after fruit set. Increased yield in Zn (0.01%) and pectin enhancement with B (0.03%) was found at two weeks after fruit set, respectively. Minimum physiological loss in weight of fruits was with Ca (0.5%) sprayed at two weeks after fruit set. In general, for most of the desirable characters 0.5% potassium (K) spray at 2 weeks after fruit set had better results.  相似文献   

17.
Samples from 70 horizons from UK soils were tested for structural stability, and a comparison was made between the results from the following six tests: (i) Emerson, (ii) Janse & Koenigs, (iii) Thorburn, (iv) Childs (soil moisture characteristic), (v) Williams & Cooke slump test, and (vi) wet sieving. Both correlations and systematic differences were observed between the tests, suggesting that different aspects of stability were emphasized by different test procedures. The tests leading to classes (i), (ii) and (iii) were found to be more subjective than those leading to indices. It is suggested that (v) may be applicable to less stable soils, and (vi) to more stable soils. Childs' test was time consuming and subject to some erratic results; two new indices of stability are proposed to increase the reliability of this test.  相似文献   

18.
Kudzu (Pueraria montana), a vigorous, perennial warm-season invasive legume is widely spread in the southeastern United States and has the potential to be used as feed by ruminants during its growing season from May until first frost (usually in October). The purpose of this study was to determine the nutritive value of kudzu during a drought-prone growing season. Five samples of apical leaves and stems were harvested once a week from random locations within a 43-year-old kudzu infestation grown on a Cecil clay loam (fine, kaolinitic, thermic Typic Kanhapludults) at the Clemson University Experimental Forest (Clemson, S.C.). We report the effects of plant part, sampling date, mean air temperature (MAT), and precipitation on dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), calcium (Ca), magnesium (Mg), phosphorus (P), potassium (K), sulfur (S), zinc (Zn), copper (Cu), manganese (Mn), and iron (Fe) of the kudzu. Dry matter and CP were significantly greater in the apical leaf than in the stem; CP had a significant mean air temperature by plant part interaction. A significant temperature by plant part interaction also existed for Mg. Magnesium was greater in leaf than in the stem at the beginning of the growing season until the end of October, when small differences in Mg concentrations between stem and leaf were observed. Stem and leaf Ca concentrations were not significantly different. Calcium concentrations did vary across the dates (P?=?0.002). A significant temperature by plant part interaction existed for Mg concentrations (P?=?0.003), Ca to P ratio (P < 0.0001), P concentrations (P?=?0.0007), S (P < 0.0001), Zn (P?=?0.0053), Mn (P?=?0.0014), and Cu (P?=?0.006). Overall, kudzu's nutritive value as feed for ruminants during the growing season is highly variable; however, chemical composition was very comparable to other common forages. More frequent and intensive droughts predicted as a result of climate change may limit forage choices; however, kudzu maintains its forage potential for feeding both domestic and wild animals during drought-prone growing season.  相似文献   

19.
This research deals with the effects of exogenous growth regulators on mineral nutrition of the tomato plant (Lyeopersieon esaulentum Mill. cv. Miguel Pereira). To study the influence on mineral nutrition, (2‐chloroethyl) trimethylammonium chloride (CCC) , at concentration of 2,000 ppm, succinic acid‐2, 2‐dimethylhydrazide (SADH) (4,000 ppm), gibberellic acid (GA) (100 ppm), (2‐chloroethyl) phosphonic acid (CEPA) (200 ppm), indole‐3‐acetic acid (IAA) (100 ppm) and 6‐furfurylamino purine (FAP) (500 ppm) were applied. Higher levels of nitrogen, calcium and magnesium occurred in the stem of plants sprayed with CCC. Treatments with FAP, SADH and CEPA caused an increase in nitrogen level in the stem. CEPA also increased calcium content in stems. These growth regulators did not alter the levels of macronutrients in the leaves in relation to control.  相似文献   

20.
The upper horizons of old vineyard soils have substantial copper contents due to the traditional use of copper-based fungicides. Total copper levels in eight vineyard soils in the Rías Baixas area of Galicia (northwestern Spain) ranged from 60 to 560 mg kg(-1) (mean +/- SD = 206 +/- 170 mg kg(-1)). The adsorption of the fungicides metalaxyl (pK(a) = 1.41) and penconazole (pK(a) = 2.83) by these soils was determined using fungicide solutions of pH 2.5 and 5.5, and desorption of fungicide adsorbed at pH 5.5 was also determined. In all cases, Freundlich equations were fitted to the data with R (2) > 0.96. Penconazole was adsorbed and retained more strongly than metalaxyl, with K(F) values more than an order of magnitude greater. In the desorption experiments, both fungicides exhibited hysteresis. Soil copper content hardly affected the adsorption of metalaxyl, but K(F) values for adsorption of penconazole increased at a rate of about 0.1 mL(n) (microg of penconazole)(1-n) (microg of Cu)(-1), which is attributed to the formation of Cu(2+)-penconazole complexes with greater affinity for soil colloids than penconazole itself. Because the dependence of K(F) for penconazole adsorption on copper content was the same at both pH values, complex formation appears not to have been affected by the solubilization of 6-17% of soil copper at pH 2.5. A similar copper dependence, or lack of dependence, was observed when 100-1000 mg kg(-1) of copper was added as Cu(NO(3))(2).2H(2)O to the solutions from which the fungicides were adsorbed.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号