α-Amylase inhibitor in local Himalyan collections of Colocasia: Isolation, purification, characterization and selectivity towards α-amylases from various sources

The α-amylase inhibitor from corms of Colocasia collected from Bhota village of Hamirpur district, Himachal Pradesh was purified to 17.21 folds with 61.61% recovery using ammonium sulfate precipitation, gel filtration chromatography (sephadex G-200) and ion exchange chromatography (DEAE-sephadex). A single band of the purified inhibitor was obtained by Native-PAGE. SDS-PAGE revealed the purified inhibitor to be a monomer with molecular weight of 13,900 daltons. The nature of inhibition was found to be of non-competitive type as determined by Lineweaver-Burk plot and a K_i value of 0.54 nmole was obtained by Dixon’s plot. The inhibitor was found to be heat stable and retained 81.50% activity at 70 °C temperature. Inhibitor was found to have pH optima of 6.9. The purified inhibitor was found to have inhibitory activity against α-amylases extracted from the larvae of Callosobruchus chinensis, Tribolium castaneum, Corcyra cephalonica and midgut α-amylase of Spodoptera littoralis. 100% larval mortality of C. cephalonica was observed when fed on wheat flour mixed with 0.0036% (w/w) of purified inhibitor. Purified α-amylase inhibitor was found to inhibit the activity of human salivary α-amylase. It also had inhibitory activity against potato α-amylases and reduced sugar content in treated potato slices. The purified inhibitor was found to be a glycoprotein. In the present study, the ability of the inhibitor to inhibit insect amylases highlights its possible role in pest resistance and post harvest decay of crop plants. Inhibitory activity of α-amylase inhibitor against mammalian amylases could suggest its potential in treatment of diabetes and cure of nutritional problems, which result in obesity.     

柱状黄杆菌强毒株和弱毒株胞外蛋白中差异蛋白的初步鉴定

柱状黄杆菌(Flavobacterium columnare)是一种世界范围的水产动物致病菌,是中国重要养殖鱼类草鱼(Ctenopharyngodon idellus)、鳜(Siniperca chuatsi)等烂鳃病的病原。本研究以1972年从患"烂鳃病"草鱼上分离的两株冻干柱状黄杆菌G4和G18菌株为研究对象,并将G4株再次分离纯化得纯化菌株,命名为G4R3。对草鱼鱼苗浸泡攻毒结果显示,G4R3的LD50至少比G18的高3个数量级,因此G4R3为"强毒株",G18为"弱毒株"。利用蛋白质组学方法分析柱状黄杆菌强毒株G4R3和弱毒株G18的胞外蛋白,经过双向电泳并结合图像分析,共发现了34个点是差异表达的蛋白。胶内酶解、肽质量指纹图谱和串联质谱分析后,鉴定出其中的7个蛋白点,代表滑动蛋白K、腺酐甲硫氨酸合成酶和一种可能的膜蛋白等3种蛋白,它们可能是柱状黄杆菌的毒力因子。     

华山松大小蠹不同龄期幼虫酯酶同工酶的比较研究

利用聚丙烯酰胺凝胶电泳技术对华山松大小蠹（Dendroctonus armandi)不同龄期幼虫的酯酶同工酶进行了分析测试。结果表明华山松大小蠹不同龄期幼虫的酯酶同工酶具有个体间的差异，其差异主要表现在酶带带数、迁移率、酶带染色深浅、酶带宽窄等方面。     

类固醇激素对牛输卵管上皮细胞分泌的调节及其分泌物对小鼠胚胎发育的影响

模拟发情期（０～６ｄ）母牛外周血浆雌激素和孕酮变化水平，在添加相应水平１７β－雌二醇和孕酮的ＴＣＭ－１９９液中，培养间情期牛输卵管上皮细胞（ＢＯＥＣ）。５％ＳＤＳ－ＰＡＧＥ分析ＢＯＥＣ分泌物，发现上皮细胞受类固醇激素作用分泌的２类蛋白质分子量与自然发情期（０～６ｄ）分泌的特异蛋白相似。证明类固醇激素可以调节和启动间情期ＢＯＥＣ的分泌活动。当雌二醇浓度高达１ｍｇ／Ｌ时，即使不加孕酮，ＢＯＥＣ仍能分泌这２类蛋白质。在培养小鼠原核胚的ＣＺＢ培养液内添加牛输卵管上皮细胞分泌蛋白（ＢＯＥＰ），与添加间情期牛输卵管冲洗蛋白（ＢＯＰ）和小牛输卵管冲洗蛋白（ＣＯＰ）相比，能显著提高通过２－细胞阶段胚胎的百分率和桑囊形成率，表明ＢＯＥＰ能较好地促进胚胎的分裂和发育。但ＢＯＥＰ组的桑囊形成率显著低于对照组，表明ＢＯＥＰ中可能缺少某些低于Ｍｒ１．０×１０４的蛋白因子的协调作用，以及含有Ｍｒ３．０×１０４～５．６×１０４的分泌蛋白的抑制作用而阻碍胚胎分裂与发育。     

鹅基因PCR-SSCP分析条件优化的研究

SSCP是一种新的分子遗传标记分析方法,但影响其试验效果的因素很多。本试验从多个方面对鹅OBR基因SS-CP方法的影响因素进行分析,结果发现应用15%的聚丙烯酰胺凝胶常温下低压电泳(丙烯酰胺/N,N′-亚甲基双丙烯酰胺为29∶1)效果最佳,条带清晰,容易识别,可应用于其他SSCP分析方法的参考。     

Effect of high molecular weight glutenins and rye translocations on soft wheat flour cookie quality

The influence of high molecular weight glutenin subunits (HMW-GS) on wheat breadmaking quality has been extensively studied but the effect of different Glu-1 alleles on cookie quality is still poorly understood. This study was conducted to analyze the effect of HMW-GS composition and wheat-rye translocations on physicochemical flour properties and cookie quality of soft wheat flours. Alleles encoded at Glu-A1, Glu-B1 and Glu-D1 locus had a significant effect over physicochemical flour properties and solvent retention capacity (SRC) profile. The null allele for Glu-A1 locus presented the highest cookie factor observed (CF = 7.10), whereas 1BL/1RS and 1AL/1RS rye translocations had a negative influence on CF. The three cultivars that showed the highest CF (19, 44 and 47) had the following combination: Glu-A1 = null, Glu-B1 = 7 + 8, Glu-D1 = 2 + 12 and no secalins. Two prediction equations were developed to estimate soft wheat CF: one using the HMW-GS composition and the other using physicochemical flour parameters, where SRCsuc, SRC carb, water-soluble pentosans, damaged starch and protein turned out to be better CF predictors. This data suggests that grain protein allelic composition and physicochemical flour properties can be useful tools in breeding programs to select soft wheat of good cookie making quality.     

亏缺灌溉与有机肥结合对夏玉米水分及产量影响

为了解减少灌水量和尿素对夏玉米产量和水分的影响。通过田间试验,以夏玉米为研究对象,选取课题组研发的有机质含量高、保水性能强的有机肥,结合2个水平的灌溉(充分灌溉W1和亏缺灌溉W2),采用等氮的原则,对有机肥与无机肥混施(F1:100%无机化肥;F2:24%有机肥+76%无机化肥;F3:48%有机肥+52%无机化肥),研究灌水量与有机无机肥对夏玉米水分利用效率和产量的影响。结果表明:与F1处理相比,在充分灌溉(W1)条件下,F2和F3处理的籽粒产量提高4.8%~6.3%;亏缺灌溉(W2)条件下,有机肥处理的籽粒产量提高1.8%~2.3%。在相同灌溉水平下,有机肥处理显著提高收获时土壤贮水量,为冬小麦发芽和生长提供一定的湿度。施有机肥处理对三叶期和小喇叭口期株高有显著影响,而对其他生育期株高影响不显著。亏缺灌溉(W2)和施有机肥(F2)的处理产量较好,是夏玉米种植管理中的一个有效方案。这种灌溉施肥管理可为关中平原及环境相似地区提供科学依据。     

PAM(聚丙烯酰胺)应用于西北黄土地区旱作农业的经济分析

我国西北地区雨养(旱作)农业面积广大、产量低而不稳。水是限制农作物产量的关键因素。地表使用PAM可以提高降雨入渗、提高作物产量。该文从理论分析和试验数据出发，研究用PAM进行旱作农业的经济性。分析了作物产量函数关系，得到PAM降雨入渗增加和作物产量增加的关系。由试验数据，得到了用PAM增加作物可用水量的定量关系。建立了定量计算不同降雨量、作物价格和PAM成本比条件下采用PAM提高作物生产经济效益的函数关系。用相关数据计算得到用PAM种植玉米的经济效益。结果表明种植玉米使用PAM可以产生很好的经济效益。说明在西北黄土地区用PAM进行旱作农业在经济上是可行的。     

沟灌土壤侵蚀控制效应的室内模拟试验研究

灌溉地土壤侵蚀问题已经越来越引起人们的普通关注。该文采用微型水槽的室内模拟试验，对利用PAM及波涌灌溉等技术减少沟灌引起的土壤侵蚀效果进行了试验研究，分析了在不同坡度、不同流量条件下PAM及灌溉间歇时间对侵蚀的影响。结果表明：PAM可显著减少沟灌土壤侵蚀量，地面坡度是地面灌溉土壤侵蚀最主要影响因素，而流量及波涌灌间歇时间对它的影响较小。     

秸秆改良材料对冷沙黄泥中速效磷含量的影响

以重庆分布面积较大的沙质土壤——冷沙黄泥为研究对象,将秸秆进行生物预处理后与膨润土、聚丙烯酰胺(PAM)按比例配制成土壤改良材料,采用盆栽土培试验方法,研究了水稻、小麦、玉米和油菜4种秸秆改良材料对冷沙黄泥速效磷含量的影响.结果表明:(1)4种秸秆改良材料均能明显提高冷沙黄泥的速效磷含量,其顺序由高到低为油菜、玉米、水稻和小麦,它们施入土壤后速效磷的平均含量分别增长了约39.4%~55.7%,38.9%~54.8%,34.5%~46.1%和28.1%~42.5%.(2)相同秸秆条件下不同分处理对土壤速效磷的增磷效果有所差异,其中秸秆∶膨润土∶PAM=900∶100∶30的T3处理对提高土壤有效磷含量的效果最好.