氮素营养水平对烟叶衰老及质体色素代谢的影响

[目的]研究不同氮素营养水平下烟叶衰老特性及质体色素代谢的差异。[方法]选取豫烟10号(YY10)、中烟100(ZY100)、NC893个品种,设置60、45、30 kg/hm23个氮素营养水平,对叶片衰老过程中相关指标进行测定分析。[结果]在同一施氮处理下,衰老速度快的品种,叶绿素和可溶性蛋白积累量较小且降解量较大,同时SOD、POD、CAT活性低,LOX活性高,MDA积累量大,质体色素降解量大,香气物质含量高;随着施氮量增加,烟叶叶绿素、可溶性蛋白和GS活性升高且出现峰值推迟的现象。[结论]该研究可为提高烟叶产质量提供科学依据。     

陕农138小孢子不同发育时期蛋白质差异的比较分析

为了探索小麦花药发育过程中的蛋白质代谢机理,利用SDS-PAGE电泳对陕农138花药单核早期、单核中晚期和双核期小孢子的全蛋白电泳谱带进行了分析.结果表明,双核期同时出现2条明显的条带或表达丰度大的条带,其分子量分别为50.7、48.2 kD,而这两个条带分别在单核早期和单核中晚期单独出现,认为通过电泳所获得的这些差异蛋白很可能直接或间接参与小孢子发育过程中某些关键的代谢途径;单核中晚期是小麦花药培养中出愈率最高的时期,这些差异蛋白又很可能与小麦花药培养力的表达调控和代谢机理有关.     

基于1H NMR技术的乳热奶牛血清代谢组学分析

【目的】应用¹H谱核磁共振（¹H NMR）技术筛选乳热奶牛血清内差异表现的小分子代谢物,从小分子水平和物质、能量代谢的角度探究奶牛发生乳热时其体内的代谢变化。【方法】选取年龄、胎次、体况和泌乳量相近的分娩当天的荷斯坦高产奶牛共32头,根据其血清中钙离子浓度及其有无临床症状分为两组。其中,24头奶牛为健康对照组（Group1, 血钙浓度 > 2.5 mmol·L^-1,无其他任何症状）和8头乳热组（Group2, 血钙浓度 < 1.4 mmol·L^-1,伴有明显乳热临床症状）。32头奶牛分别于清晨饲喂和榨乳前从颈静脉采集血液10 mL,置于离心管中,4℃下以1 500 × g 离心20 min,将离心得到的血清装入1.5 mL的EP管中,置于-80℃下待测。待样品解冻后,分别从每个EP管中抽取400 μL血清,加入200 μL缓冲盐溶液,充分混合、离心后,提取550 μL上清液置于5 mm核磁管中,在500 MHz的核磁共振波谱仪下采集信号。然后利用Topspin和MestReNova等软件将采集到的信号进行傅里叶转换,同时进行调零、校正基线和相位等预处理,去除水峰和尿素峰信号,将一维图谱进行积分分段,并将图谱信息转换为TXT格式文件,以便于后续数据分析,然后使用Chenomx软件进行化合物指认。最后应用SIMCA-P软件对得到的图谱数据进行多元统计分析,包括主成分分析（PCA）和正交修正-偏最小二乘法-判别分析（OSC-PLS-DA）, 同时结合SPSS软件对核磁数据进行单因素方差分析得到的P值以及Loading图,最终筛选出表现差异的小分子代谢物。【结果】本试验成功得到了乳热组和健康对照组奶牛的血清代谢图谱及差异表达代谢物的Loading图;PCA结果显示每组样品均在95%置信区间内,无需剔除,主成分贡献率较低,其中PC1=26.2%,PC2=16.7%,组间差异变量不能被选择;OSC-PLS- DA结果显示经过5次正交信号修正,与分组无关的变量被去除,组间差异达到最大化;与健康对照组相比,共筛选出9种血清差异表达代谢物,其中4种表达上调,分别为 β-羟基丁酸、丙酮、丙酮酸和赖氨酸,5种表达下调,分别为葡萄糖、丙氨酸、丙三醇（甘油）、磷酸肌酸和氨基丁酸;9种差异代谢产物多为糖和氨基酸,相互之间形成了一个能量转化网络图,通过多种代谢途径参与了机体能量代谢过程,其中较为特殊的差异代谢产物,如磷酸肌酸可直接为机体提供能量,其表现降低可能与病牛肌无力和瘫痪有关。此外,本试验中乳热组奶牛氨基丁酸降低,临床表现为精神沉郁、甚至昏迷,这与人类抑郁症患者的氨基丁酸表现相吻合,有关氨基丁酸下降与奶牛乳热精神的关系有待研究者进一步证实。【结论】¹H NMR技术能够被应用于筛选奶牛血清表现差异的小分子代谢物,代谢物差异显著;本试验中乳热奶牛血清差异代谢产物表现出能量负平衡及脂肪动员的病理学特征,提示乳热与能量代谢障碍有关。     

不同种类叶菜积累硝酸盐能力差异及其原因探讨

采用相同营养液水培的方式研究了7种叶菜硝酸盐的积累差异及其原因。结果表明,7种叶菜叶片硝酸盐含量差异较大,这种差异主要是由于不同叶菜叶片硝酸还原酶活性的差异、根系对硝酸盐的吸收速率和叶片中硝酸盐的代谢库和贮存库的不同造成的;不同叶菜叶片硝酸盐含量与硝酸还原酶活性和代谢库的大小呈明显的负相关,与贮存库和吸收速率呈明显的正相关;叶菜的生长状况影响叶片的硝酸盐含量。     

柠檬水饮用治疗妊高病患者便秘的效果观察

目的探讨柠檬水治疗妊高病患者便秘的效果及其护理方法.方法将60例3d无大便妊高病患者分为2组,一组采用常规饮食治疗,另一组在饮食治疗基础上,加以柠檬水饮用.两组进行对照,观察排便效果.结果两组患者排便效果差异有显著性（P〈0.05）.结论柠檬水饮用治疗妊高病患者便秘的效果明显优于常规饮食治疗,值得临床广泛推广.     

Soil microbial biomass response to woody plant invasion of grassland

Woody plant proliferation in grasslands and savannas has been documented worldwide in recent history. To better understand the consequences of this vegetation change for the C-cycle, we measured soil microbial biomass carbon (C_mic) in remnant grasslands (time 0) and woody plant stands ranging in age from 10 to 130 years in a subtropical ecosystem undergoing succession from grassland to woodlands dominated by N-fixing trees. We also determined the ratio of SMB-C to soil organic carbon (C_mic/C_org) as an indicator of soil organic matter quality or availability, and the metabolic quotient (qCO₂) as a measure of microbial efficiency. Soil organic carbon (C_org) and soil total nitrogen (STN) increased up to 200% in the 0–15 cm depth increment following woody plant invasion of grassland, but changed little at 15–30 cm. C_mic at 0–15 cm increased linearly with time following woody plant encroachment and ranged from 400 mg C kg⁻¹ soil in remnant grasslands up to 600–1000 mg C kg⁻¹ soil in older (>60 years) woody plant stands. C_mic at 15–30 cm also increased linearly with time, ranging from 100 mg C kg⁻¹ soil in remnant grasslands to 400–700 mg C kg⁻¹ soil in older wooded areas. These changes in C_mic in wooded areas were correlated with concurrent changes in stores of C and N in soils, roots, and litter. The C_mic/C_org ratio at 0–15 cm decreased with increasing woody plant stand age from 6% in grasslands to <4% in older woodlands suggesting that woody litter may be less suitable as a microbial substrate compared with grassland litter. In addition, higher qCO₂ values in woodlands (0.8 mg CO₂-C g⁻¹ C_mic h⁻¹) relative to remnant grasslands (0.4 mg CO₂-C g⁻¹ C_mic h⁻¹) indicated that more respiration was required per unit of C_mic in wooded areas than in grasslands. Observed increases in C_org and STN following woody plant encroachment in this ecosystem may be a function of both greater inputs of poor quality C that is relatively resistant to decay, and the decreased ability of soil microbes to decompose this organic matter. We suggest that increases in the size and activity of C_mic following woody plant encroachment may result in: (a) alterations in competitive interactions and successional processes due to changes in nutrient dynamics, (b) enhanced formation and maintenance of soil physical structures that promote C_org sequestration, and/or (c) increased trace gas fluxes that have the potential to influence atmospheric chemistry and the climate system at regional to global scales.