Drugs from bugs: the use of insects as a valuable source of transgenes with potential in modern plant protection strategies

Transgenic expression of antimicrobial peptides in crops has become a novel approach among the strategies to combat phytopathogens in modern plant protection measures. The first antimicrobial transgenes of insect origin, modified cecropins, have been demonstrated to confer resistance of several transgenic cultivars against both bacterial and fungal phytopathogens. Insects represent a promising reservoir for antimicrobial peptides to engineer disease resistant crops. The increasing knowledge about the potent insect innate immunity may help to develop a novel strategy in sustainable agriculture. Several approaches are presently under investigation to prevent evolution of phytopathogens that can overcome disease resistance in transgenic crops expressing an insect antimicrobial peptide. Pathogen-induced expression of insect antimicrobial peptides in crops and combined multiple expression of different antimicrobial peptides along with proteinase inhibitors from insects may prevent selection of resistant phytopathogens. The potential of insect antimicrobial peptides as transgenes to render disease resistant crops has just started to be explored and may provide tools to be ahead of the evolutionary adaptability of phytopathogens.     

响应面法优化酶解提取金枪鱼鱼油的工艺研究

[目的]研究蛋白酶提取鱼油的工艺,为鱼油的提取研究提供参考。[方法]利用金枪鱼蒸煮油水混合液为原料,采用胰蛋白酶进行水解,以鱼油提取率为考察指标,采用响应面分析方法研究酶解提取金枪鱼鱼油的最佳工艺条件。[结果]试验得到酶解提取金枪鱼鱼油的最佳工艺条件为:加酶量1.71%、pH 7.94、时间4.22 h、温度44℃,在该条件下制备的鱼油提取率达90.23%。经脱胶、脱酸、脱色及脱臭制得的鱼油符合精制鱼油1级标准,其中DHA和EPA含量分别为27.71%和5.94%。[结论]采用胰蛋白酶对金枪鱼蒸煮油水混合液进行水解提取鱼油具有一定的可行性。     

Influence of barley inclusion method and protease supplementation on growth performance,nutrient utilisation,and gastrointestinal tract development in broiler starters

The influence of the method of barley inclusion(fine,coarse and whole barley)in a wheat-based diet and protease supplementation(0 and 0.20 g/kg)on growth performance,nutrient utilisation and gastrointestinal tract development of broilers(d 1 to 21)was evaluated in a 3
2 factorial arrangement.Whole barley(WB)grains were ground in a hammer mill to pass through the screen sizes of 2.5 and 8.0 mm to achieve fine(FB)and coarse(CB)barley particle sizes,respectively.A total of 288,one-day-old male broilers were allotted to 36 cages(6 cages/treatment;8 birds/cage).There was no significant(P>0.05)interaction between barley inclusion method and protease for any growth performance or nutrient utilisation parameters.Birds fed diets containing CB and WB showed higher(P<0.05)weight gain,and digestibility of dry matter,nitrogen,calcium,gross energy,and ileal digestible energy compared to those fed FB diets.Compared to the birds fed FB diets,feed per gain was lower(P<0.05)in birds fed diets made of WB.Fat digestibility of the birds fed CB was higher(P<0.05)than those fed FB and WB birds.Compared to FB and CB diets,inclusion of WB resulted in heavier(P<0.05)gizzards but reduced(P<0.05)gizzard pH.Supplemental protease,however,had no effects(P>0.05)on growth performance and nutrient utilisation,most likely due to the well balanced digestible amino acids and high inherent digestibility of protein in the basal diet,and/or the presence of exogenous carbohydrase and phytase.In conclusion,the present results showed that the inclusion of coarsely ground and whole barley in a wheat-based diet can enhance nutrient and energy utilisation and is beneficial to the growth performance of young broilers.     

百草枯对土壤中蛋白酶和过氧化氢酶活性影响研究

［目的］研究百草枯对土壤中蛋白酶和过氧化氢酶活性的影响。［方法］设4个百草枯处理水平,分别于培养2、6、12、20、30、45和60 d时取样测定蛋白酶和过氧化氢酶的活性。［结果］1 000 μg/g百枯草处理的酶活性低于其他4个处理。100 μg/g百枯草处理的蛋白酶活性的最低值出现在第20天,其余3个百草枯处理的蛋白酶活性的最低值均出现在第12天。1 000 μg/g百枯草处理的蛋白酶抑制率在第20天达51.08%,在第60天为41.48%。200、500和1 000 μg/g百枯草处理均不同程度地抑制过氧化氢酶活性,且其抑制作用随着百草枯浓度的增加而增强。1 000 μg/g百枯草处理对过氧化氢酶的抑制率在第12天达66.18%,在第60天为39.18%。［结论］百草枯对土壤中蛋白酶和过氧化氢酶的活性有较大的影响。     

黄曲霉固态发酵麻疯树饼粕产蛋白酶及其酶学性质研究

[目的]利用黄曲霉固态发酵麻疯树饼粕产蛋白酶,研究产酶工艺条件及其酶学性质。[方法]将黄曲霉接种含麻疯树饼粕的固体发酵培养基,采用福林法测定在不同湿度条件、不同碳源或氮源条件以及不同培养时间下所产蛋白酶的活力。饱和硫酸铵法纯化蛋白酶,并测定其在不同催化温度、不同pH条件和不同有机溶剂处理下的活力,分析其催化动力学。[结果]控制相对湿度为50%,向培养基中添加0.10g/ml乳糖和0.02g/ml蛋白胨,30℃下发酵5d,蛋白酶活力最高。蛋白酶的最适催化温度为45℃,最适作用pH值为6.0,最大催化速度Vmax为3333.33μg/min,Km为31.25mg/ml,有机溶剂可以适当提高蛋白酶活力。[结论]利用黄曲霉固态发酵产蛋白酶是利用麻疯树饼粕的有效途径。     

葡萄籽多肽的制备及功能研究

本试验用风味蛋白酶及碱性蛋白酶,以pH值、酶用量及时间为因素,采用三因素三水平L9(33)正交试验确定葡萄籽多肽制备最佳的酶和酶解条件,结果表明,碱性蛋白酶优于风味蛋白酶,碱性蛋白酶的最佳水解条件是pH值为11.5、酶用量为0.9%、水解时间为18h的条件下达到最大水解度46.16%。葡萄籽多肽有很强的清除DPPH.和H2O2的能力,有一定的清除O2-.和抑制脂质过氧化能力,且总还原力随浓度增加而增加。葡萄籽多肽对金黄色葡萄球菌、志贺氏菌、枯草芽孢杆菌、大肠杆菌1515、黑曲霉和青霉都有较强抑制作用,其抑菌率分别为70.77%、65.28%、59.07%、60.71%、60.71%和50.86%。另外,葡萄籽多肽具有很好的乳化性和乳化稳定性。结果表明该多肽中存在抗氧化肽、抑菌肽、表面活性肽。     

A Study on Heat Resistance and Initial Characterization of Protease Inhibitors in Porcine Colostrum

Porcine colostrum was separated into the acid-soluble fraction (SF) and casein fraction (CF) by acidifying followed by centrifuge. SF was further separated by liquid chromatography and anisotropic membrane filtration. Capacities of the SF or CF of porcine colostrum, to inhibit trypsin and chymotrypsin activity and to inhibit the epidermal growth factor (EGF) degradation in pig small intestinal contents, were determined under different heat treatments. The study showed that trypsin inhibitors in porcine colostrum survived heat treatments of 100℃ water bath for up to 10 min, but exposure to boiling water bath for 30 min significantly decreased the inhibitory activity. Compared with the trypsin inhibitors, the chymotrypsin inhibitors were more heat-sensitive. SF was more heat-sensitive than CF. Separation of the SF of porcine colostrum by liquid chromatography and anisotropic membrane filtration revealed that the porcine colostrum protease inhibitors, those had the capacity to inhibit the trypsin-chymotrypsin activity and enhanced the stability of EGF in the gastrointestinal(GI) lumen of weaned pigs, existed mainly in SF, milk-derived, were a group of heat-labile small proteins with molecular weight of 10 000-50 000.     

水稻白叶枯病菌的胞外酶与毒力关系的初步研究

研究了水稻白叶枯病菌60个菌株所产生的胞外蛋白酶、纤维素酶(Cx)和果胶酶的活力及其产生胞外粘多糖的能力。从总体看,蛋白酶活力与菌株毒力成正相关,而纤维素酶活力与菌株毒力相关不显著。但来自华南地区的一些菌株的毒力与纤维素酶活力显著相关,而与蛋白酶没有显著的相关性。蛋白酶和纤维素酶的产生都受培养基中氮源成分的影响。尚未发现果胶酶活力及粘多糖产生能力与毒力有任何关系。     

乌龙茶加工中蛋白酶活性与相关生化成分的变化

以毛蟹和梅占两品种鲜叶为原料 ,用新工艺加工成乌龙茶 ,并对晒青、做青过程中在制品的蛋白酶活性及其相关化学成分进行了分析 ,结果表明 :晒青和做青均有利于蛋白酶的活化。晒青、做青前中期酶活性缓慢上升 ,第二次摇青、静置后达到最大值。第一、二次摇青期间以叶缘的酶活性最高 ,叶芯的最低 ;做青结束时 ,叶缘的活性仍保持最高 ,但整叶的酶活性最低。晒青和做青也有利于氨基酸和可溶性蛋白的积累 ,氨基酸积累量要多于可溶性蛋白质。调节蛋白酶活性使之处于适当水平 ,对乌龙茶新工艺把握适度做青的理论将有所补充