肥大细胞对重组口蹄疫病毒VP1-VP4应答的蛋白质表达谱检测

为揭示肥大细胞抗口蹄疫病毒VP1-VP4蛋白的天然免疫作用,以重组口蹄疫病毒VP1-VP4蛋白刺激小鼠腹腔肥大细胞(Peritoneal mast cells,PMCs),用高通量ELISA芯片检测PMCs的蛋白质表达谱。结果显示,VP1-VP4蛋白刺激的PMCs(VP1-VP4组)表达CCL19、L-selectin、CCL17和TNF-α的水平极显著低于对照组(PMCs)(P0.001),而VP1-VP4蛋白刺激经甘露糖受体(Mannose receptor,MR)抑制剂预处理的PMCs(MR组)表达CCL19、IL-15、IL-9、G-CSF和Galectin-1的水平则极显著高于对照组(P0.01),IL-10表达水平也有显著升高(P0.05)。MR组与VP1-VP4组相比,PMCs表达IL-10、IL-17、CCL20、IL-15、IL-9、L-selectin、CCL17、TNF-α和CCL19的水平极显著升高(P0.01),CCL21和G-CSF的表达也显著高于VP1-VP4组(P0.05)。生物信息学差异表达分析结果显示,与对照组相比,VP1-VP4组PMCs表达的L-selectin和CCL17为下调性差异表达蛋白(Log2(ratio)≤–1)。MR组与VP1-VP4相比,PMCs表达的CCL20、CCL19、L-selectin和IL-15为上调性差异表达蛋白(Log_2(ratio)≥1)。这表明,PMCs可自发分泌CCL19、L-selectin、CCL17和TNF-α,而VP1-VP4则对PMCs的天然免疫功能具有抑制作用。由于阻断MR后PMCs的蛋白质表达水平显著升高,所以VP1-VP4对小鼠PMCs的免疫抑制作用可能是由MR介导的。     

不同栽培模式对冬小麦-夏玉米轮作系统产量、氮素累积和平衡的影响

以河北山前平原区秸秆还田条件下小麦-玉米轮作体系为研究对象,设置农民习惯、高产高效、再高产和再高产高效4个模式,通过定位试验探讨各栽培模式对3个轮作周期作物产量、土壤硝态氮累积量及氮平衡的影响.结果表明: 小麦、玉米产量均以再高产模式最高,高产高效和再高产高效模式次之,均显著高于农民习惯模式;小麦季和玉米季氮肥利用效率(PFP)均以高产高效模式最高,显著高于其他模式;0～400 cm土体硝态氮累积量在 768.4～1133.3 kg·hm^-2之间,其中80%～85%累积在根下90～400 cm土层;4种模式的土壤硝态氮均有明显向下淋移现象,120～150 cm和270～330 cm处均出现了累积峰,以270～330 cm土层硝态氮累积量最大;高产高效模式的土壤硝态氮含量整体水平均低于其他模式,浓度基本维持在30 mg·kg^-1以下,在一定程度上能有效缓解环境压力;冬小麦季0～90 cm土体氮素盈余量均小于夏玉米季,并以高产高效模式的氮素表观损失量最低,显著低于其他模式.综合考虑产量、氮肥利用效率、硝态氮累积和氮平衡,以高产高效模式表现最优,但还有一定的提升空间.     

不同氮肥喷涂吡啶对夏玉米田氮素利用及土壤N2O排放的影响

为减少土壤N₂O排放,提高作物氮素利用,采用田间试验法研究了不同氮肥用量喷涂一定比例的吡啶(0、180、270、360 kg N·hm^-2)对夏玉米生育期内土壤N₂O排放和氮素表观损失、籽粒产量及氮素利用的影响.结果表明:不同氮肥用量下喷涂吡啶的土壤N₂O排放主要集中在播种-苗期和拔节-抽雄期,基肥和追肥后均会出现显著的土壤N₂O排放通量高峰.随氮肥用量增加,玉米产量不断增加,但270和360 kg N·hm^-2间无显著差异,2种施氮量下的玉米分别净增收5209和5426元·hm^-2.与不施氮肥比,各施氮处理下的玉米籽粒吸氮量提高幅度为109.6%～134.1%.各处理间的氮肥农学效率和氮肥利用率均以氮肥喷涂吡啶270 kg N·hm^-2较大,而土壤氮素表观损失较小.氮肥喷涂吡啶在270 kg N·hm^-2时玉米增产增收,氮肥利用效率较高,土壤N₂O排放和氮素表观损失较少,是一种较为合理的氮肥调控施用技术.     

铁尾矿区油松根际溶磷泛菌D2的筛选鉴定及溶磷特性

从河北省迁安市马兰庄镇铁尾矿植被恢复区油松根际分离出2株溶磷细菌,经过平板初筛和摇瓶复筛得到1株溶磷能力较强的菌株D2.通过菌落形态、生理生化特性及16S rDNA序列分析,确定此菌株D2属于泛菌属.利用液体发酵试验测定不同碳源、氮源对菌株D2溶磷能力的影响,通过高效液相色谱测定D2在不同氮源条件下产生有机酸的种类和浓度.结果表明:菌株D2对磷酸三钙有较强的溶磷能力,培养液有效磷含量最高为392.13 mg·L^-1,菌株D2的溶磷能力在碳源为葡萄糖、氮源为硫酸铵时效果最好;高效液相色谱测定发现,不同氮源条件下,D2分泌有机酸的种类和浓度存在差异,以硫酸铵、氯化铵、硝酸钾、硝酸钠、硝酸铵为氮源,均产生草酸、甲酸、乙酸和柠檬酸,以硫酸铵、氯化铵、硝酸铵为氮源还产生苹果酸.相关性分析表明,乙酸含量与有效磷含量间呈显著正相关(r=0.886,P<0.05),表明溶磷泛菌D2分泌的乙酸对无机磷的溶解有明显的促进作用,这也很可能是该菌株的重要溶磷机制之一.     

不同微生物菌剂对基质酶活性和番茄产量及品质的影响

以鸡粪配方基质(腐熟鸡粪:腐熟玉米秸秆:河沙体积为3:4:3)和牛粪配方基质(腐熟牛粪:腐熟玉米秸秆:河沙体积为3:4:3)为试材,研究了基质中分别添加地福来、酵素菌、EM菌、枯草芽孢杆菌和农用微生物菌剂对基质酶活性和番茄产量及品质的影响.结果表明: 两种配方基质添加微生物菌剂40和60 d时根际基质的脲酶、蔗糖酶和碱性磷酸酶活性均显著提高,番茄植株生长量、果实产量及维生素C含量显著高于对照.鸡粪和牛粪配方基质均以添加地福来效果最好,番茄单株产量分别较各自对照增加14.7%和40.0%,果实维生素C含量分别提高22.2%和39.7%.在不添加微生物菌剂的情况下,鸡粪配方基质栽培的番茄单株产量和果实维生素C含量高于牛粪配方基质;分别添加地福来后,两种基质栽培的番茄单株产量和果实维生素C含量无显著差异.     

Effects of yeast culture (Saccharomyces cerevisiae) on ruminal digestion in non-lactating dairy cows

Six non-lactating dairy cows fitted with ruminal cannulas were used in a cross-over design, to investigate the effects of supplemental yeast culture (Saccharomyces cerevisiae) (YC) and interaction of YC by sampling time on ruminal fermentation and in situ fibre degradation. Cows were fed twice daily with a diet composed of 67% corn silage, 32% concentrate and 1% vitamin and mineral mixture, on a dry matter (DM) basis. Concentrates were not mixed with silage. YC (0.5% DM) significantly decreased rumen ammonia from 148.5 mg l⁻¹ to 103.1 mg l⁻¹ 3 h post-feeding, and significantly increased by about 20% the concentration of total volatile fatty acids before and 1 h after feeding. YC significantly increased molar percentage of propionate and decreased the acetate : propionate ratio before feeding. No significant effect was observed on ruminal pH and molar percentages of acetate or butyrate. Pattern of degradation of DM, neutral and acid detergent fibre from hay was affected, with a cubic effect of interaction of YC by incubation time. However, magnitude of degradation was not significantly different at any time. These results show that modifications of ruminal fermentation due to YC addition are time dependent when the diet is fed twice daily.     

Evaluation of high-performance liquid chromatography for the separation and determination of arsenic species by on-line high-performance liquid chromatographic-hydride generation-atomic absorption spectrometry

An on-line high-performance liquid chromatographic-microwave assisted oxidation-hydride generation-atomic absorption spectrometric (HG-AAS) system (using columns of different kinds) has been developed for the determination of arsenite, arsenate, dimethylarsinate (DMA), monomethylarsonate (MMA), arsenobetaine (AsB) and arsenocholine (AsC) in environmental samples. Ion-pair reversed-phase chromatography using tetrabutylammonium phosphate as the ion-pair reagent and anion-exchange chromatography were evaluated and the analytical performances of each are reported. The detection limits were 97–143 and 10–30 μg l⁻¹ for ion-pair reversed-phase and anion-exchange chromatography, respectively. The Hamilton PRP-X 100 anionic column was proposed for the determination of the six species; AsB can be quantitated independently of AsC by taking the difference between readings at pH 6 and pH 10.7. The proposed methods were applied to water samples and sediments and their potential for future application was demonstrated.     

Cold-stress response in the amphibian oocyte: changes in synthesis and nucleocytoplasmic distribution of some proteins

In vivo cold stress was found to induce characteristic changes in the protein synthesis pattern of Pleurodeles waltl oocytes, as analyzed by two-dimensional gel electrophoresis. The nature of the response varied with the duration and intensity of stress. After a short period of cold stress (12 h at 8°C), synthesis and intracellular distribution of polypeptides were dramatically disturbed. There occured: 1) a reduction in synthesis of several polypeptides, including two major polypeptides (54-kDa and 47-kDa); 2) changes in distribution of polypeptides in oocyte, ie some polypeptides (185- and 96-kDa) were blocked in the cytoplasm, while other polypeptides (82-, 74-, 72- and 68-kDa, actin and nucleoplasmin) continued to enter the nucleus, but were quantitatively reduced; 3) no changes in the distribution of two nuclear polypeptides (53- and 43-kDa); 4) changes in the relative quantities of β- and γ-actin and preferential migration of γ-actin towards the nucleus. After a long period of in vivo cold stress (5 days at 8°C), we noted a partial recuperation of synthesis and nuclear migration (except for a 96-kDa polypeptide), but a persistent perturbation at the level of actin. For more drastic stress conditions (4°C), such a recuperation of protein synthesis was never observed.