鸡蛋壳壳膜及表面角质层去除方法的优化与比较

本文拟对EDTA法、蛋白酶K法和NaOH法去除鸡蛋壳壳膜及表面角质层的条件进行优化并比较,以期获得分离蛋壳有机层和矿化晶体层的有效方法。通过SS-550扫描式电子显微镜观察发现,EDTA法中以5%EDTA处理鸡蛋壳30min的效果相对较好,能去除蛋壳内膜及尽可能多的外膜,但是表面角质层的去除效果较弱;蛋白酶K法中以50μg/mL蛋白酶K孵育鸡蛋壳48h的效果相对较好,能完全去除表面角质层和蛋壳内膜,但蛋壳外膜尚不能彻底去除干净;而NaOH法中则以2%NaOH于99℃中煮鸡蛋壳17min的效果最理想,既能彻底去除壳膜又能完全去除表面角质层。3种方法相比,去除鸡蛋壳壳膜及角质层的理想方法是于99℃的2%NaOH中煮17min。     

螯合诱导植物修复中污染土壤的重金属淋滤行为

采用土柱淋滤试验,研究乙二胺二琥珀酸(EDDS)和乙二胺四乙酸(EDTA)诱导植物修复过程中的土壤重金属淋滤行为,同时比较了香根草(Vetiveria zizanioides L.)和玉米(Zea mays L.)在减少重金属淋滤方面的作用.结果表明,在25 d内经过480 mm降雨的淋洗, EDDS处理的土柱(80 cm土层)没有出现重金属的淋滤;而EDTA明显导致表层土壤重金属向下层土壤迁移,该迁移行为与降水量的大小、种植植物与否关系密切.香根草和玉米可明显延缓EDTA引起的土壤重金属向下层土壤的淋滤,且香根草的延缓效果好于玉米.上述结果表明,EDDS诱导的高生物量植物修复是相对安全的,而使用EDTA需要考虑当地的降水条件.     

3种萃取剂对土壤重金属的去除及其对重金属有效性的影响

通过重金属污染土壤的浸泡试验,比较了HCl、柠檬酸、EDTA3种萃取剂对污染土壤中3种重金属Pb、Cd、Zn的去除能力,并研究了这3种萃取剂的萃取对土壤重金属有效性的影响。结果表明,随着浓度的提高,3种萃取剂对Pb、Cd、Zn的去除作用增强。EDTA去除3种重金属的能力远远大于其他2种萃取剂。HCl和柠檬酸对3种重金属去除率的顺序均为Cd>Zn>Pb,EDTA溶液对3种重金属去除率的顺序为Pb>Cd>Zn。HCl和柠檬酸萃取提高了土壤Pb的有效性,降低了Cd、Zn的有效性。EDTA萃取降低了土壤Pb、Cd、Zn的有效性,并且这3种重金属的有效性低于HCl和柠檬酸的处理。可见,EDTA作为治理重金属污染土壤的萃取剂比HCl和柠檬酸更合适,HCl和柠檬酸虽然也能明显地去除土壤中的重金属,但它提高土壤Pb的有效性的效应值得注意。     

几种抗氧化剂组合使用对肉粉抗氧化性能的影响

采用L9(34)正交试验设计,研究了不同组合维生素E(VE)、维生素C(VC)、柠檬酸、乙二胺四乙酸(EDTA)对肉粉的抗氧化效果.结果表明:VE 0.07%、VC 0.06%、柠檬酸0.04%、EDTA 0.09%的组合抗氧化效果最好.     

The use of divalent cation chelating agents (EDTA/EGTA) to reduce non-specific serum protein interaction in enzyme immunoassay

An indirect enzyme immunoassay (ELISA) for detection of bovine antibody toBrucella abortus was modified by the addition of divalent chelating agents to the serum diluent. This addition resulted in an increase in specificity from 96.0% in the regular assay to 99.4% in the modified procedure. Of the 15 715 sera initially tested by the indirect ELISA, 691 that had given positive reactions were selected for retesting in the indirect ELISA with EDTA/EGTA added. The buffered plate antigen test (BPAT) correctly identified 98.6% of the samples as negative. The addition of chelating agents did not alter the sensitivity of the indirect ELISA, which correctly classified 609 sera from animals from whichB. abortus had been isolated as positive. The sensitivity of the BPAT was 97.8%.Abbreviations ABTS 2,2-azinobis(3-ethylbenzthiazoline sulphonic acid) - BPAT buffered plate antigen test - EDTA ethylenediaminetetraacetic acid disodium salt - EGTA ethylene glycol-bis(-aminoethyl ether)-N,N,N,N-tetraacetic acid - ELISA enzyme-linked immunosorbent assay - IgG₁ immuno- globulin G₁ - IgM immunoglobulin M - Tris tris(hydroxymethyl)aminomethane     

Effects of ethylenediaminetetraacetic acid on phytate phosphorus utilization and efficiency of microbial phytase in broiler chicks

Previous studies have suggested that organic acids may improve P utilization in animals. To evaluate the ability of ethylenediaminetetraacetic acid (EDTA) to improve phytate P utilization and the possible synergistic effect between EDTA and microbial phytase (MP) an experiment was conducted using 360 Ross 308 broiler chicks. The experiment was carried out using a completely randomized design with a 3*2 factorial arrangement (0, 0.1 and 0.2% EDTA and 0 and 500 IU MP). Four replicate of 15 chicks per each were fed dietary treatments including (i) P-deficient basal diet [0.2% available phosphorus (aP)] (NC); (ii) NC + 500 IU MP per kilogram of diet; (iii) NC + 0.1% EDTA per kilogram of diet; (iv) NC + 0.1% EDTA and 500 IU MP per kilogram of diet; (v) NC + 0.2% EDTA per kilogram; and (vi) NC + 0.2% EDTA + 500 IU MP per kilogram of diet. Weight gain (WG), feed efficiency and serum Ca, P and alkaline phosphatase (ALP) were assessed. Addition of 0.2% EDTA to low aP diets resulted in significantly lower feed consumption (FC) and WG, but 0.1% EDTA did not depress WG compared to NC. Phytase supplementation of P-deficient diets significantly improved WG and feed efficiency, but it had no effect on FC. Microbial phytase supplementation significantly decreased ALP concentration. Results obtained in our study suggest no synergistic effect between phytase and EDTA in broiler chicks.     

Changes in carbohydrate levels and their metabolic enzymes in leaves,phloem sap and mesocarp during cucumber (Cucumis sativus L.) fruit development

Levels of carbohydrates and activities of metabolic enzymes were examined in leaves (source), phloem sap (flow) and mesocarp tissues (sink) in the course of cucumber (Cucumis sativus L.) fruit development, from 2 days before anthesis to 20 days after anthesis. While total sugar levels increased in all the three sampling organs, starch levels declined in leaves and mesocarp tissues as fruit development progressed. Glucose and fructose were the primary contributors to the soluble sugar pools in mature leaves. Stachyose was found as the most important component of the phloem sap extracts, followed by sucrose and raffinose. However, the primary sugars accumulated in mesocarp tissues were glucose and fructose, not stachyose or sucrose. Activities of sucrose synthesizing enzymes (sucrose phosphate synthase plus sucrose synthase in the synthesizing direction) exceeded that of sucrose degrading enzymes (acid invertase, neutral invertase plus sucrose synthase in the degrading direction) in leaves, which might cause a sucrose pool utilized in raffinose and stachyose biosynthesis. While alkaline a-galactosidase form I activity declined, stachyose synthase activity showed a rapid increase until 12 days after anthesis and only subsequently decreased in leaves. Activities of sucrose degrading enzymes were always much higher than that of sucrose synthesizing enzymes in mesocarp tissues. Thus, sucrose accumulation could not occur in mesocarp tissues. While stachyose synthase activity steadily decreased, alkaline a-galactosidase form I activity showed a moderate increase before decrease in mesocarp tissues. The relationship between levels of soluble sugars and activities of relative enzymes was also discussed.     

EDTA辅助下地被石竹对铅污染土壤的修复潜力

采用盆栽试验,研究了铅(Pb)污染土壤添加乙二胺四乙酸(EDTA)对地被石竹生长及吸收Pb的影响.结果表明,未施用EDTA情况下,地被石竹的转运系数和生物富集系数分别为0.31～0.40,0.25～1.58,且植株含Pb量随土壤Pb浓度的提高而显著增加.施用EDTA情况下,转运系数为0.59～1.41,地上部含Pb量最高值可达1 432.81 mg·kg-1.125、250、500、1 000 mg·kg-1的Pb添加水平上,施用5 mmol·kg-1EDTA的处理,Pb迁移总量分别是2 234.61、2 013.30、5 600.84和2 083.16 μg·盆-1,转运量系数为0.71、0.74、0.80和0.90;10 mmol·kg-1EDTA处理下,迁移总量分别是2 275.26、4 032.95、4 578.92和1 977.05 μg·盆-1,转运量系数为0.80、0.84、0.90、0.91.因此,地被石竹对Pb有较强的耐性,在EDTA辅助下具有超富集Pb的潜力.     

EDTA对桑树和任豆幼苗吸收重金属Pb的影响

【目的】研究不同重金属Pb2＋浓度下螯合剂EDTA处理对桑树和任豆幼苗修复土壤中重金属Pb2＋的效果及Pb2＋在植物茎叶及根部积累,以期为重金属污染土壤生态修复及植物资源的合理利用提供理论依据。【方法】用盆栽模拟法,以4L／盆Hoagland营养液作为培养液,培养液中的Pb2＋浓度分别为0、2．5、5．0、10．0、25．0、50．0、100．0、150．0、200．0、250．0mg／L,EDTA的浓度均为0．55mmol／L,以不添加EDTA作对照。分别测定桑苗和任豆幼苗茎叶和根部的Pb2＋浓度。【结果】随着水培液中Pb2＋浓度的增加,桑树和任豆幼苗对Pb2＋的吸收和积累量也逐渐增大;在相同的重金属Pb2＋胁迫背景下,加入EDTA的桑树和任豆幼苗对Pb2＋的吸收量比不添加EDTA的对照组明显增高;桑树和任豆幼苗体内Pb2＋浓度通常为根部〉茎叶,而添加EDTA能加速重金属Pb2＋向茎叶的转运。随着培养液中Pb2＋浓度的增加和时间的延长,Pb2＋在植物根部的积累逐渐增加,而向茎叶的转运则相对减少。【结论】桑树和任豆幼苗具有较强的重金属Pb耐性,而EDTA能促进桑树和任豆幼苗对重金属Pb2＋的吸收,因此,桑树和任豆可作为修复植物应用于重金属污染地区。     

可降解螯合剂EDDS诱导植物修复重金属污染土壤的潜力

用土培试验的方法,研究了螯合剂EDDS和EDTA对苏丹草、玉米、大豆、茼蒿、青菜吸收土壤重金属的影响。结果显示,施用5 mmol.kg-1EDDS和EDTA可以显著增加供试植物地上部Cu、Pb、Zn和Cd的含量及积累量。EDDS比EDTA具有更强的溶解土壤Cu和增加植物吸收积累Cu的能力;但对土壤Pb的溶解和增加其在植物地上部积累的作用,EDTA大于EDDS。在5种植物中,EDDS对茼蒿Cu含量和积累量的促进作用最大。EDDS处理下茼蒿地上部Cu含量和积累量分别达到973 mg.kg-1和每盆909μg。施用EDDS和EDTA后的5~30 d内,土壤水提取态Cu、Pb、Zn和Cd的含量随时间显著下降,尤其是在施用EDDS的土壤中下降更为迅速。上述结果表明,与EDTA相比,可生物降解螯合剂EDDS在诱导植物修复重金属污染特别是Cu污染土壤有很大的潜力,且环境风险较小。