外源酶和柠檬酸对奥尼罗非鱼内源消化酶活性的影响

分别研究了饲料中添加外源消化酶、非淀粉多糖酶、植酸酶和柠檬酸对奥尼罗非鱼内源消化酶活性的影响。实验结果表明,与对照组相比,饲料中分别添加15g·kg-1和30g·kg-1的消化酶制剂,胃、肝胰脏、肠道蛋白酶活性分别升高了22.3%、17.7%、12.5%(P<0.05)和42.0%、25.2%、16.5%(P<0.01),肝胰脏、肠道淀粉酶活性分别升高了62.4%、28.8%(P<0.05)和54.0%、27.4%(P<0.05),肠道脂肪酶活性分别升高了23.2%(P<0.05)和43.6%(P<0.01);添加1g·kg-1非淀粉多糖酶和植酸酶,肝胰脏、肠道淀粉酶活性分别上升11.4%、49.5%(P<0.01)和14.0%、24.1%(P<0.05),对胃、肝胰脏、肠道蛋白酶活性无显著影响;饲料中添加10g·kg-1柠檬酸使胃蛋白酶活性提高29.6%(P<0.01),肠道蛋白酶活性下降35.1%(P<0.01),肝胰脏和肠道淀粉酶分别上升30.7%和29.4%(P<0.01);饲料中添加非淀粉多糖酶、植酸酶和柠檬酸对肠道脂肪酶活性均无显著影响。     

白果活性蛋白的酶法水解及抗氧化活性研究

白果活性蛋白(GAP)是华中农业大学天然产物化学实验室首次从白果中分离得到的一种以清蛋白为主的且具有显著生物活性的蛋白,为扩大该蛋白在食品中的用途,提高其生物活性,研究了酶法水解制备白果肽段的方法及其抗氧化活性的变化。通过单因素分析、正交试验以及对试验结果的分析,确定了2709碱性蛋白酶水解白果活性蛋白的最佳水解条件为：底物浓度1%,pH值8.5,水解温度45℃,酶浓度7000 U/g,反应时间6 h。以Fenton体系和邻苯三酚体系检验其抗氧化活性,结果表明白果肽段较酶解前的活性蛋白,抗氧化活性有不同程度的提高,但两者均具有较强的抗氧化活性。     

中华稻蝗两地理种群乙酰胆碱酯酶生化特性研究

采用生物测定方法,对采自山西省临猗县和江苏省徐州市郊中华稻蝗五龄若虫的乙酰胆碱酯酶(AChE)特性进行了比较研究,同时测定了2种群五龄若虫对马拉硫磷的敏感性。用对氧磷、氧化毒死蜱和甲基内吸磷3种有机磷抑制剂对2种群中华稻蝗五龄若虫AChE的体外抑制进行的研究表明,该2种群AChE对对氧磷、氧化毒死蜱、甲基内吸磷的敏感性没有显著差异,临猗种群比徐州种群分别高1.24、1.13和0.82倍;乙酰胆碱酯酶动力学研究结果表明,临猗种群的动力学参数米氏常数(Km值)和最大反应速度(Vmax值)均较徐州种群为高;用乙酰硫代胆碱(ATC)做底物测定AChE活性,2种群AChE活性无显著差异,临猗种群是徐州种群的1.24倍。而2种群生物测定结果表明,临猗种群和徐州种群五龄若虫对马拉硫磷的敏感度有差异,徐州种群五龄若虫的LD50值(13.00μg·g-1虫质量)是临猗种群(4.64μg·g-1虫质量)的2.8倍。据此推测,中华稻蝗徐州种群马拉硫磷敏感性下降与AChE无相关性,可能存在其他影响因素。     

甲氨基阿维菌素苯甲酸盐亚致死剂量对不同敏感性棉铃虫解毒酶活性的影响

室内用甲维盐对棉铃虫选育20代,获得敏感性降低2.32倍的汰选种群(RP20)。分别采用甲维盐对同源对照种群(CP)和RP20的亚致死浓度LC25对应处理两种群的3龄初幼虫48 h,测定试虫在3~6龄不同龄期内羧酸酯酶(CarE)和谷胱甘肽S 转移酶(GST)活性,分析酶活性变化动态。结果表明,(1)两种群(CP和RP20)均随龄期的增长,CarE比活力显著增大,而GST比活力先降低后趋于稳定。(2)CK处理下,RP20与CP相比,CarE比活力在3~6龄均增大且4~6龄差异显著,而GST比活力变化较小,仅3龄和6龄显著增大。(3)与CK处理相比,甲维盐LC25处理,两种群各龄期CarE比活力均增大,且CP试虫在4龄、6龄GST比活力显著增大,在3龄、5龄无显著差异,而RP20的3龄幼虫体内GST比活力被显著抑制,在4~6龄GST比活力无明显变化。初步判断,棉铃虫对甲维盐敏感性降低与CarE比活力增大有关;甲维盐亚致死剂量对棉铃虫CarE活性具有一定的诱导作用。     

苜蓿盲蝽属三种害虫对环氧虫啶的敏感性

环氧虫啶是我国自主研发的一种新型的新烟碱杀虫剂,主要用于防治刺吸式口器害虫。本文采用点滴法测定了环氧虫啶对中黑盲蝽、苜蓿盲蝽、三点盲蝽的毒力,结果表明,三种盲蝽对环氧虫啶均具有较高的敏感性,其中中黑盲蝽的敏感性最高,LD_(50)值为2.03ng/头,其次为苜蓿盲蝽和三点盲蝽,LD_(50)分别为3.12和3.34ng/头。多功能氧化酶抑制剂PBO能明显增加环氧虫啶对三种盲蝽的毒力,谷胱甘肽S-转移酶抑制剂DEM只在中黑盲蝽上对环氧虫啶表现出增效作用,而羧酸酯酶抑制剂TPP未显示增效作用。这说明,环氧虫啶具有防治苜蓿盲蝽属三种害虫的应用潜力,细胞色素P450-单加氧酶可能在环氧虫啶代谢中起重要作用。     

Purification and Characterization of a Novel Alginate Lyase from a Marine Streptomyces Species Isolated from Seaweed

Alginate, a natural polysaccharide derived from brown seaweed, is finding multiple applications in biomedicine via its transformation through chemical, physical, and, increasingly, enzymatic processes. In this study a novel alginate lyase, AlyDS44, was purified and characterized from a marine actinobacterium, Streptomyces luridiscabiei, which was isolated from decomposing seaweed. The purified enzyme had a specific activity of 108.6 U/mg, with a molecular weight of 28.6 kDa, and was composed of 260 amino acid residues. AlyDS44 is a bifunctional alginate lyase, active on both polyguluronate and polymannuronate, though it preferentially degrades polyguluronate. The optimal pH of this enzyme is 8.5 and the optimal temperature is 45 °C. It is a salt-tolerant alginate lyase with an optimal activity at 0.6 M NaCl. Metal ions Mn²⁺, Co²⁺, and Fe²⁺ increased the alginate degrading activity, but it was inhibited in the presence of Zn²⁺ and Cu²⁺. The highly conserved regions of its amino acid sequences indicated that AlyDS44 belongs to the polysaccharide lyase family 7. The main breakdown products of the enzyme on alginate were disaccharides, trisaccharides, and tetrasaccharides, which demonstrated that this enzyme acted as an endo-type alginate lyase. AlyDS44 is a novel enzyme, with the potential for efficient production of alginate oligosaccharides with low degrees of polymerization.     

土壤水分能量与土壤生化活性

用人工模拟土柱研究了(土娄)土与河淤土的水势对土壤生化强度的影响。结果表明,在相同含水量下,由于两土壤的水分实际有效性不同,显示出两土壤生化强度的差异。从而认为在相同水势下比较土壤间的生化活性,才能真实地反映土壤水分对土壤生化活性的影响。温度引起的土壤生化强度的变化,在采用水势概念时,还包含着温度对土壤水分有效性的影响。     

不同纤维来源饲粮和细胞壁降解酶对猪肠道微生物菌群多样性的影响

本试验旨在利用末端限制性片段长度多态性技术研究不同纤维来源饲粮和细胞壁降解酶对猪肠道微生物菌群多样性及其组成结构的影响。试验选用8头平均体重为(35.0±2.5)kg的"杜×长×大"三元杂交生长猪,统一安装回肠末端T型瘘管,随机分为4组,每组2个重复。试验分4期,每期每组猪按4×4拉丁方设计饲喂小麦麸、小麦麸加酶、大豆皮和大豆皮加酶4种试验饲粮之一。每期预试期15 d,正试期6 d。试验结果表明:1)大豆皮饲粮组猪回肠食糜微生物的多样性显著高于小麦麸饲粮组(P0.05)。2)小麦麸饲粮组显著提高猪回肠食糜中普氏菌属(Prevotella)和乳酸杆菌属(Lactobacillus)的丰度(P0.05),而大豆皮饲粮组则显著提高猪回肠食糜中瘤胃球菌属(Ruminococcus)及粪便中拟杆菌属(Bacteroides)、毛螺菌属(Lachnospira)的丰度(P0.05)。3)添加细胞壁降解酶显著提高各饲粮组猪回肠食糜中Lachnospira、真细菌属(Eubacterium)及粪便中Lachnospira的丰度(P0.05),但也同时降低了回肠食糜中Lactobacillus、Prevotella及粪便中Lactobacillus、Bacteroides和克雷伯氏菌属(Klebsiella)的丰度(P0.05)。综上所述,纤维饲粮可显著提高猪肠道内非淀粉多糖降解菌的丰度,而细胞壁降解酶则可选择性改变肠道微生物菌群的多样性及其组成。     

Ameliorative effects of inoculation with the plant growth-promoting rhizobacterium Pseudomonas sp. DW1 on growth of eggplant (Solanum melongena L.) seedlings under salt stress

The objective of this work was to evaluate the effect of inoculation with the plant growth-promoting rhizobacterium Pseudomonas sp. DW1 on eggplant (Solanum melongena L.) growth, mineral uptake and activities of the antioxidant enzymes including superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) of plant leaves under salinity stress. The study was conducted in pot experiments using eggplant (S. melongena L., cv. Yinjia) and a coastal soil. The NaCl concentration of the coastal soil was 0.57 g (kg soil)⁻¹. Four NaCl levels were tested: 0.57, 1.0, 2.0, and 3.0 g NaCl (kg soil)⁻¹, by adding NaCl to soil, respectively. Pseudomonas-inoculated seeds had an increase in the germination percentage over its non-inoculated seeds under salinity. Salinity negatively affected growth of eggplant; however, plants inoculated with Pseudomonas sp. DW1 grew to a significantly greater extent than plants that were not treated with this bacterium. Salinity significantly decreased K⁺ concentration, increased Na⁺ concentration, and did not significantly decrease Ca²⁺ content in shoots of eggplants. Inoculating with Pseudomonas sp. DW1 increased shoot Ca²⁺ of eggplant compared to the non-inoculating eggplant plants under salinity. Inoculating treatments with Pseudomonas sp. DW1 had no effect on shoot Na⁺ concentration in 0.57 and 1 g (kg soil)⁻¹ NaCl, but there were significant decreases in inoculated treatments than in non-inoculated ones at 2 and 3 g (kg soil)⁻¹ NaCl. Salinity decreased SOD activities and increased POD activities, and inoculated Pseudomonas sp. DW1 had an increase effect on SOD activity in the leaves of eggplants. Alteration of mineral uptake and increase in the antioxidant enzyme activities may be two mechanisms for the alleviation of salt stress. Based on the results of the experiment reported herein, the use of the plant growth-promoting rhizobacterium treatment may provide a means of facilitating plant growth under salt stress.     

Vc、β-葡聚糖和藻粉对中国对虾幼虾生长、成活率及免疫酶活性的影响

在中国对虾幼虾的基础饲料中分别添加不同剂量的维生素C(0、0.015%、0.030%、0.045%、0.060%)、β-葡聚糖(0、0.050%、0.075%、0.100%)和藻粉(0、2%、5%、7%),未添加组为对照组,探讨维生素C(Vc)、β-葡聚糖和藻粉对中国对虾幼虾成活率、相对增长(重)率及肌肉酸性磷酸酶(ACP)、过氧化氢酶(CAT)、超氧化物歧化酶(SOD)、溶菌酶(LSZ)活性的影响。室内网箱饲养40 d试验结果表明,饲料中添加Vc后,0.030%组幼虾相对增重率和CAT活性显著高于对照组(P<0.05),0.045%组ACP、CAT活性显著高于对照组(P<0.05),但Vc对SOD活性没有显著性影响,0.015%组LSZ活性极显著高于对照组(P<0.01);0.075%β-葡聚糖组的相对增重率、SOD活性显著高于对照组(P<0.05);添加7%藻粉能极显著提高相对增长(重)率(P<0.01),但ACP和LSZ活性呈极显著下降(P<0.01),添加5%藻粉能显著提高CAT活性(P<0.05)。