超声辅助酶法制备海参性腺ACE抑制肽及其模拟体内消化稳定性的研究

该研究利用超声波技术（0～500 W,0～35 min）辅助中性蛋白酶（0.5%～5%,1 h～6 h,1 500 U/g～7 500 U/g）水解海参性腺制备血管紧张素转化酶（angiotensin convert enzyme,ACE）抑制肽,再经过模拟体内消化试验分析海参性腺ACE抑制肽的消化稳定性。试验结果表明：随着超声功率、超声时间、底物浓度、酶解时间和酶添加量的增加,ACE抑制率先增加后降低。随超声功率、超声时间和底物浓度的增加,水解度具有相同的变化趋势;随着酶解时间和加酶量的增加,水解度逐渐上升后趋于平稳。根据水解度和ACE抑制率得出可以高效制备海参性腺ACE抑制肽的超声预处理和酶解反应条件：超声预处理功率200 W,时间15 min,底物浓度2%,酶添加量4 500 U/g,酶解时间2 h,海参性腺酶解液的水解度和ACE抑制率均较高,分别为7.81%和73.81%。此条件下制备的海参性腺ACE抑制肽经超滤后进行胃肠模拟消化试验,消化前后海参性腺ACE抑制肽的活性无显著性差异（P＞0.05）,表明其在体内能够表现出良好的稳定性,具有稳定的降血压功效。     

一种微生物发酵产蓝色素的稳定性及毒性研究

天然蓝色素十分罕见，直接采用微生物发酵并能用于食用的天然蓝色素至今未见报道。我们利用一株链霉菌（Ｓｔｒｏｐｔｏｍｙｃｅｓ）ＬＳ－１进行发酵，对其产生的蓝色素的稳定性、毒性进行了研究。实验结果表明本色素是蓝色粉末，几乎无臭无味，易溶于水和含水乙醇，在碱性时呈鲜明蓝色，在酸性时呈红色，耐热（８０～１００℃６０ｍｉｎ）不褪色，在ｐＨ＞７时光（包括紫外光）稳定性强，金属离子Ｎａ＋、Ｍｇ２＋对本色素无影响。本色素对革兰氏阴性细菌、酵母菌及丝状真菌无抑制作用，对革兰氏阳性细菌有微弱的拮抗作用。粗品毒性试验ＬＤ５０＞１５０００ｍｇ／ｋｇ，致突变试验阴性，色素粗品属无毒。发酵液色价吸光度（１０倍稀释水溶液）０．４（λｍａｘ＝５８１ｎｍ），发酵周期８０±２ｈ。研究结果认为本色素是一种很有开发前景的微生物天然蓝色素。     

α-乳白蛋白源ACE抑制肽快速筛选及验证

采用生物信息学手段，利用在线工具对α-乳白蛋白进行虚拟酶解，通过对活性肽的活性、毒性及理化性质进行预测，并结合分子对接的方法实现快速精准筛选新的血管紧张素转化酶（angiotensin I-converting enzyme，ACE）抑制肽Pro-Glu-Trp（PEW）。通过固相合成法制备出活性肽PEW进行体外活性验证，其半抑制浓度（IC50）为3?130?μmol/L。全柔性分子对接模拟结果表明，PEW与ACE活性口袋S1相互作用可能是其具有ACE抑制活性的主要原因，氢键、疏水作用力、静电力是维持两者结合的主要作用力。与传统方法相比，本研究可以快速高效地筛选出ACE抑制肽，为食源性活性肽的快速筛选提供了新思路。     

加酶挤压对小麦淀粉结构和理化性质的影响

本文旨在探究加酶挤压对小麦淀粉结构和理化性质的影响。分别设置浓度梯度为0%、0.1%、0.2%、0.5%、1%、2%的α-淀粉酶-小麦淀粉混合物样品,挤压处理后,利用扫描电镜（SEM）、差示扫描量热仪（DSC）、X-射线衍射仪（XRD）、快速粘度仪（RVA）等分析淀粉结构与理化性质的变化。结果表明:各处理组的堆积密度无显著差异（P>0.05）;吸水指数与加酶量呈负相关,水合指数与加酶量呈正相关;挤压后淀粉糊化度均大幅度提高,接近完全糊化;挤压后淀粉的颗粒结构被完全破坏且加酶使得淀粉颗粒粒径更小;加酶挤压处理后相对结晶度降低,从原淀粉的17.52%降至10.29%（酶浓度2%）;挤压处理后小麦淀粉的糊化焓均显著下降（P<0.05）,挤压淀粉样品焓值最低,仅为0.24 J/g,加酶挤压淀粉的焓值高于挤压淀粉,随着加酶量的增加,淀粉的焓值上升至2.5 J/g左右;RVA曲线可明显看出处理组的粘度远低于原淀粉粘度,且加酶挤压样品粘度低于不加酶挤压粘度。本文探明了加酶挤压对淀粉结构和理化性质的作用规律,可为加酶挤压技术在淀粉基食品领域的应用提供理论指导。     

DMSO胁迫提高发光细菌毒性实验敏感度的研究

利用二甲基亚砜(DMSO)胁迫,以发光细菌青海弧菌Q67种为实验菌种,通过与标准物质作用测定相对发光值确定其生物毒性效价,对多种食品中可能存在的污染物进行毒性对比研究。结果表明,DMSO浓度在0.1%~1.0%之间不影响发光细菌正常生理反应,同时可以有效的提高其对毒性物质作用毒性。DMSO能明显提高发光细菌的检测敏感度,有效降低半数致死量EC50。对受试重金属汞、铜、镉和锌,其提高效率为43.28%~58.50%;四环类抗生素中盐酸金霉素、盐酸四环素和土霉素的提高效率在8.2%~11.6%之间;抗菌类农药二氰蒽醌、溴菌腈、甲霜灵和异菌氟腚胺的提高效率为10.49%~38.32%。DMSO的胁迫促进效果适用于多种毒性物质,并且能够在短时间内提高作用效果(30 min以内),为食品领域应用生物毒性检测方面提供了一种新的分析方法。     

响应面法优化黄粉虫蛋白制备ACE抑制肽的条件

以黄粉虫蛋白粉为原料,利用酶解技术对制备血管紧张素转换酶（angiotensin converting enzyme,ACE）抑制肽进行优化。通过单因素及响应面试验,确定木瓜蛋白酶的酶解工艺,利用酶标法测定酶解产物的ACE抑制率,研究底物质量浓度、加酶量、pH值、酶解时间、酶解温度对ACE抑制肽活性的影响。结果表明：当底物质量浓度为7 g/100 mL、加酶量1%、pH 6.5、酶解时间7 h、酶解温度55 ℃时,黄粉虫蛋白粉酶解产物的ACE抑制率达到58.86%。     

黄酮混合物体外抗氧化活性的相互作用

测定槲皮素、异槲皮素、杨梅素、山萘酚、儿茶素、表儿茶素、芹菜素、飞燕草素-3-O-葡萄糖苷、矢车菊素-3-O-葡萄糖苷等9种黄酮类化合物及其两两混合物的体外抗氧化活性,以研究黄酮混合物的协同、拮抗与加合作用。以DPPH清除能力、羟基自由基清除能力、总抗氧化性、还原能力为评价指标。结果表明,含有较多B环羟基的黄酮类化合物更易发生拮抗作用,可通过调节黄酮单品的比例减小混合物的拮抗作用或是增强其协同作用,不同反应机理的评价指标所得结果不同。     

硒对铅毒性拮抗作用的研究进展

铅是环境中重要的重金属污染物,对人体的各个系统均能产生毒性和损伤。硒是人体必需的微量元素之一,大量研究表明,硒与铅存在着相互拮抗作用。硒和铅在动物或人体内的含量呈负相关,硒不仅能够拮抗铅的吸收和蓄积,促进铅的排泄,还能拮抗铅导致的机体各组织和细胞的氧化应激和免疫损伤、神经系统毒性、听力损伤、遗传和生殖毒性、肝肾毒性、DNA损伤等毒性作用。本文从上述几方面综述了近年来硒对铅毒性拮抗作用的研究进展。硒在人体内发挥生理作用主要通过硒蛋白实现,本文还阐述了硒拮抗铅毒性的作用与硒蛋白的关系方面的研究进展。尽管如此,硒拮抗铅毒性作用的研究机制仍然不明确。此外,硒对人体的营养必需剂量和毒性剂量之间的范围非常窄,因此,研究硒对人体健康的保护作用的剂量效应关系是实施科学补硒的前提和基础。     

桑叶蛋白活性多肽的酶解制备

该研究旨在探讨蛋白血管紧张素转换酶（angiotensin I-convening enzyme,ACE）抑制肽及抗氧化肽的酶解制备方法。选取3种蛋白酶（碱性蛋白酶、中性蛋白酶及芽孢杆菌蛋白酶）酶解制备桑叶功能活性多肽,以ACE抑制活性为主要指标并辅以水解度（degree of hydrolysis,DH）评价ACE抑制活性,以DPPH自由基清除能力和总抗氧化能力（total antioxidant capacity,T-AOC）为指标评价其抗氧化性能。运用单因素逐级优化法对酶解反应的酶解pH值、底物浓度、加酶量、酶解温度和酶解时间进行参数优化。结果表明,3种蛋白酶的酶解产物均具有ACE抑制活性,中性蛋白酶酶解产物效果最佳,酶解工艺条件为底物浓度20 g/L、加酶量7.5%、酶解时间50 min、酶解温度55℃、pH7.0时,酶解产物的ACE抑制活性为81.23%,DH为21.41%。在不同蛋白酶优化条件下测定3种酶解产物的抗氧化能力,中性蛋白酶DPPH自由基清除率和总抗氧化能力均为最高,分别为80.702%和4.717 mmol/g。     

发光菌冻干粉保护剂及贮藏效果的研究

探究脱脂乳类复合保护剂在冷冻干燥过程中对青海弧菌Q67(V.qinghaiensis sp.-Q67)和明亮发光杆菌T3(P.phosphoreum sp.-T3)相对发光率的影响,并对保护剂进行优化;-20、4℃以及室温(16～25℃)条件下对两种发光菌冻干粉的贮藏效果进行比较研究。结果表明:明亮发光杆菌T3对冷冻干燥的抗性要高于青海弧菌Q67;3种保护剂中,以脱脂乳、蔗糖、壳聚糖混合物为保护剂的两种发光菌粉复苏30min后的发光度最高;以脱脂乳、蔗糖、壳聚糖、谷氨酸钠混合物为保护剂的青海弧菌Q67菌粉在-20℃条件下长期贮藏效果最好;而对明亮发光杆菌T3菌粉长期贮藏而言,3种保护剂在-20、4℃和室温条件下的效果均较好。这两种菌粉在30min内快速反应,表明它们在毒性物质快速检测中有着较好的应用价值。     

杀虫剂混配五种增效剂防治葡萄斑叶蝉初报

用3种化学药剂与5种增效剂混配,进行葡萄斑叶蝉的田间药效试验。结果表明,3种杀虫剂吡虫啉、阿克泰和吡蚜酮混配渗展宝(SZB)、菲蓝(FL)、一可佳(YKJ)、杰效利(JKL)、弹指间(TZJ)5种增效剂可延长持效期,减少药剂的施用量。吡虫啉与菲蓝混配制剂药后14 d效果较好,阿克泰与渗展宝、菲蓝、弹指间混配药后的14 d防效均为100%;吡蚜酮与菲蓝、渗展宝混配制剂药后7 d的防效100%。所有增效剂与杀虫剂混用后均比单独使用效果得以提升。     

Alteration of mammalian-cell toxicity of pesticides by structural iron(II) in ferruginous smectite

The ultimate concern over pesticides in the environment is their toxic impact on nontarget organisms, including humans. Soil clays are known to interact with pesticides in ways that decrease the concentration of the parent compound in the soil solution (adsorption, sequestration, degradation). These phenomena are generally regarded as beneficial, but toxicological verification is lacking. In this study, mammalian-cell cytotoxicity of four commonly used agricultural chemicals (2,4-D, alachlor, dicamba, and oxamyl) was assessed after exposure to either reduced or oxidized ferruginous smectite (SWa-1). Results revealed that treatment with reduced smectite produced differential effects on mammalian-cell viability, depending on the pesticide. Oxamyl and alachlor reacted with reduced SWa-1 showed a significant decrease in their overall cytotoxic potential. Dicamba reacted with the reduced-clay treatment and generated products that were more toxic than the parent pesticide. Finally, no differences were observed between redox treatments for 2,4-D. The significance of these results is that oxidized smectites have virtually no influence on the toxicity of pesticides, whereas reduced-Fe smectite plays an important role in altering the cytotoxic potential of agricultural pesticides. The Fe oxidation state of clay minerals should, therefore, be taken into account in pesticide management programs.     

高毒农药替代药剂SP003防治甘蔗螟虫试验

为配合国家禁用高毒农药政策的开展,积极推进新型高效低毒药剂的推广,广西农垦北部湾总场进行了高毒农药的替代药剂SP003颗粒剂防治甘蔗螟虫的田间试验。结果表明,该种药剂对甘蔗苗期螟虫防治效果达86.6%～87.6%,对后期死尾的控制达可以作为呋喃丹等高毒农药替代品种用于甘蔗螟虫的防治。     

Distribution and toxicity of sediment-associated pesticides in agriculture-dominated water bodies of California's Central Valley

The agricultural industry and urban pesticide users are increasingly relying upon pyrethroid insecticides and shifting to more potent members of the class, yet little information is available on residues of these substances in aquatic systems under conditions of actual use. Seventy sediment samples were collected over a 10-county area in the agriculture-dominated Central Valley of California, with most sites located in irrigation canals and small creeks dominated by agricultural effluent. The sediments were analyzed for 26 pesticides including five pyrethroids, 20 organochlorines, and one organophosphate. Ten-day sediment toxicity tests were conducted using the amphipod Hyalella azteca and, for some samples, the midge Chironomus tentans. Forty-two percent of the locations sampled caused significant mortality to one test species on at least one occasion. Fourteen percent of the sites (two creeks and four irrigation canals) showed extreme toxicity (>80% mortality) on at least one occasion. Pyrethroid pesticides were detected in 75% of the sediment samples, with permethrin detected most frequently, followed by esfenvalerate > bifenthrin > lambda-cyhalothrin. Based on a toxicity unit analysis, measured pyrethroid concentrations were sufficiently high to have contributed to the toxicity in 40% of samples toxic to C. tentans and nearly 70% of samples toxic to H. azteca. Organochlorine compounds (endrin, endosulfan) may have contributed to the toxicity at a few other sites. This study provides one of the first geographically broad assessments of pyrethroids in areas highly affected by agriculture, and it suggests there is a greater need to examine sediment-associated pesticide residues and their potential for uptake by and toxicity to benthic organisms.     

农药混剂对烟草蚜虫的联合毒力测定

在确定的测定条件下 ,采用孙云沛共毒系数法对 9种杀虫剂的 10个组合对烟蚜的联合毒力进行了测定。结果表明 ,共毒系数大于 10 0 ,有增效作用的组合有 :“功夫” +“敌敌畏”、“灭蚜宁” +“敌百虫”、“敌杀死” +“敌百虫”、“西维因” +“敌百虫”和“功夫” +“敌杀死” ,其共毒系数分别为 82 2 .4、795 .5、70 8.3、4 0 0 .9和 30 7.1;其余 5个组合共毒系数小于 10 0 ,表明有拮抗作用。有增效作用的组合可做进一步的室内及田间小区试验     

Supplemental feeding with glycerol or propylene glycol of dairy cows in early lactation--effects on metabolic status, body condition, and milk yield

The objective of this field study was to evaluate the effect of supplemental feeding with glycerol or propylene glycol to dairy cows in early lactation on metabolic status, body condition and milk yield. In total, 673 newly calved cows from 12 commercial Swedish dairy herds were randomized to daily supplementation with 450 g of glycerol (GLY), 300 g of propylene glycol (PG), or nothing (control, CON). Supplements were fed twice daily from 0 to 21 d in milk (DIM) as a top dress on concentrates. For each cow, data on parity, breed, calving date, monthly test-day milk yield, and cases of diseases were collected. Blood samples were taken at approximately 2, 5, and 8 wk postpartum (pp) and analyzed for glucose, β-hydroxybutyrate (BHBA), nonesterified fatty acids (NEFA), and insulin. Samples taken within 3 wk pp were also analyzed for insulin-like growth factor 1 (IGF-1). Measurements of body condition score (BCS) and heart girth (HG) were obtained at approximately 2 and 5 wk pp and at time of first insemination. The effects of supplemental feeding with GLY or PG on the plasma concentrations of glucose, NEFA, BHBA, insulin, and IGF-1, and BCS, HG, and occurrence of disease were analyzed. No differences in BCS or HG or in plasma concentrations of glucose, BHBA, NEFA, or IGF-1 were found between the control group and any of the treatment groups. Cows in the GLY group had lower plasma insulin concentrations during DIM 0 to 63 compared with group CON, but no difference in insulin was found between the PG group and the CON group. Cows supplemented with GLY had a higher milk yield (kg of milk and kg of energy-corrected milk) during the first 90 DIM. Cows in the PG group tended to yield more milk during the same period. No differences in the occurrence of diseases were seen between the groups. In conclusion, supplementation with GLY in early lactation did increase milk yield without a subsequent decrease of metabolic status, and supplementation with PG tended to do the same.     

杀虫剂对烟蚜的毒力测定及药效试验

为筛选防效较好的杀虫剂 ,于 2 0 0 2年进行了 5种杀虫剂对烟蚜的室内 (浸渍法 )毒力测定及田间防效试验。室内毒力测定结果表明 ,5种杀虫剂对烟蚜的相对毒力指数排序为 :“艾美乐” >“虫螨克星” >“金世纪” >“阿耳发特” >“乐果” ;田间试验结果表明 ,70 %“艾美乐”15 0 0 0倍液、1 8%“虫螨克星”30 0 0倍液和 3%“金世纪”15 0 0倍液对烟蚜防效较好 ,在施药后 7d对烟蚜的校正防效分别为99 74 %、99 6 7%和 99 90 % ,并具有持效期较长、防治效果稳定的特点。     

Mixture toxicity of reactive chemicals by using two bacterial growth assays as indicators of protein and DNA damage

The mixture toxicity of reactive chemicals was investigated with a set of bioanalytical tests that quantify not only the toxic effects but also allow the identification of the preferred target of reactive chemicals in bacterial cells. Softer electrophiles such as acrylates react preferentially with thiol groups in proteins and peptides, and harder electrophiles such as epoxides preferentially attack DNA. In addition, some compounds, e.g., benzyl chloride, have no preference for a biological target and damage both DNA and proteins. A thiophenol was used as a model compound representing nucleophiles. We explored if the paradigms of mixture toxicity also hold true for reactive chemicals. Compounds with the same targets and the same modes of action should act concentration additive in mixtures, and compounds with different modes of action should act according to the concept of independent action. In addition, we investigated the potential for interaction of compounds of mixtures of electrophiles or electrophiles plus nucleophiles, which might lead to synergistic or antagonistic effects. The toxicity of mixtures of electrophiles with a single preferred target was consistent with the prediction for concentration addition. Unfortunately, the predictions for independent action did not differ much from those for concentration addition; therefore it was not possible to differentiate between these two models. Mixtures of two groups with different preferred target sites clearly showed concentration addition. In contrast, mixtures of compounds with multiple targets, i.e., compounds that show nonspecific reactivity toward any biological nucleophile, exhibited effects that lay distinctly between the predictions for concentration addition and independent action. We observed neither synergism (higher toxicity than predicted by concentration addition) nor antagonism (lower toxicity than predicted by independent action) for mixtures of electrophiles. Binary combinations of different electrophiles with the nucleophile 4-chlorothiophenol yielded smaller effects than those expected from the prediction for independent action. The degree of antagonism was correlated with the reaction rate constant of the electrophile with the thiol group of glutathione, which indicates that the interaction between the mixture components occur in the toxicokinetic phase and is purely a result of chemical reactivity between the mixture components. Overall, we conclude that the concepts of mixture toxicity apply not only for baseline toxicity and receptor-mediated mechanisms, as has been shown in a large number of studies, but also for reactive mechanisms of toxicity, provided that one has checked beforehand that no chemical reactions occur between the mixture components.     

Thresholds for the effects of pesticides on invertebrate communities and leaf breakdown in stream ecosystems

We compiled data from eight field studies conducted between 1998 and 2010 in Europe, Siberia, and Australia to derive thresholds for the effects of pesticides on macroinvertebrate communities and the ecosystem function leaf breakdown. Dose-response models for the relationship of pesticide toxicity with the abundance of sensitive macroinvertebrate taxa showed significant differences to reference sites at 1/1000 to 1/10,000 of the median acute effect concentration (EC50) for Daphnia magna, depending on the model specification and whether forested upstream sections were present. Hence, the analysis revealed effects well below the threshold of 1/100 of the EC50 for D. magna incorporated in the European Union Uniform Principles (UP) for registration of single pesticides. Moreover, the abundances of sensitive macroinvertebrates in the communities were reduced by 27% to 61% at concentrations related to 1/100 of the EC50 for D. magna. The invertebrate leaf breakdown rate was positively linearly related to the abundance of pesticide-sensitive macroinvertebrate species in the communities, though only for two of the three countries examined. We argue that the low effect thresholds observed were not mainly because of an underestimation of field exposure or confounding factors. From the results gathered we derive that the UP threshold for single pesticides based on D. magna is not protective for field communities subject to multiple stressors, pesticide mixtures, and repeated exposures and that risk mitigation measures, such as forested landscape patches, can alleviate effects of pesticides.     

基于食品安全指数法的台山市蔬菜和水果农药残留风险评估

该研究监测了2019~2021年台山市10个类蔬果中16种农药的残留量,采用食品安全指数法（Index of Food Safety,IFS）和危害物风险系数法（Hazard Risk Coefficient,R）对其进行安全水平评估。结果表明,1 928份蔬果样品中,34份不合格,总体合格率为98.24%,芽菜类等3类蔬菜合格率低于总体水平,毒死蜱和克百威超标占比达35.90%。食品安全指数法显示,叶菜类蔬菜 为2.59,安全状态不可接受,豆类蔬菜等5类 为0.066~0.38,安全状态可以接受,其余4类安全状态良好;氟虫腈等3种农药IFS为0.68~14.05,对安全性影响不可接受,其余13种农药IFS为0.005 8~0.76,对安全性影响可以接受。危害物风险系数法显示,毒死蜱等5种农药风险系数R为2.67~6.10,处于高风险,丙溴磷等4种风险系数R为1.91~2.22,处于中风险,其余7种均为低风险。建议监管部门应采取多种评价方法综合评估农药残留风险,加大风险品种蔬果、中高风险以及对安全影响较高的农药残留监测,同时提高快检技术在监管工作的覆盖面,加大植物生长调节剂和新型农药快检技术研发。