基于亲水相互作用液相色谱-三重四极杆质谱法研究白茶萎凋过程中代谢物的变化

采用亲水相互作用液相色谱-三重四极杆质谱法,对白茶鲜叶(F)和室内萎凋处理29 h(W)、53 h(P)的2个萎凋样进行了代谢物靶向检测,Quality control(QC)样本中共检测到111个代谢物,主要包括47种氨基酸及其衍生物、29种核酸类代谢物、12种维生素和辅酶、17种糖代谢物和6种甘油磷脂代谢物。与鲜叶F相比,萎凋叶W和P中显著增加的代谢物分别有39种和41种,其中共有代谢物35种;显著降低的代谢物分别有9种和11种,其中共有代谢物8种。显著变化代谢物分析结果表明,萎凋叶的细胞膜受损、DNA和RNA降解、氨基酸衍生物显著增加、糖代谢异常。根据代谢物含量的变化幅度和组成特异性,筛选了表征萎凋叶细胞膜生理状态和核酸、糖代谢的标志代谢物。此外,针对代谢物中氨基酸和核苷酸的组成特点,提出了研究氨基酸衍生物滋味特性的必要性和应用代谢谱分析建立萎凋工艺适度标准的可能性。     

Application of urease inhibitor improves protein composition and bread‐baking quality of urea fertilized winter wheat

Background: Nitrogen losses is an economic problem for wheat production and a high risk to the environment. Therefore, improved N fertilizer management is a key to increasing the N efficiency and minimizing N losses. To increase N efficiency, enhanced fertilizers such as urea combined with urease inhibitor can be used. Aims: The aim of present study was to evaluate the effects of different N forms on grain storage protein subunits in winter wheat and to examine whether the observed changes correlate with parameters of baking quality. Methods: The investigation was performed over two consecutive years at two locations in Germany. Protein subunits were analyzed by SDS‐PAGE. Results: Protein concentrations were similarly increased after fertilization with ammonium nitrate and urea + urease inhibitor. Analysis of the individual storage protein fractions indicated that both fertilizers specifically enhanced ω‐gliadins and HMW glutenins, but the effect was more pronounced in the ammonium nitrate treatment. Application of urea + urease inhibitor had greater influence on the protein composition and resulted in higher specific baking volume as well as the best fresh keeping ability, in comparison with urea treatment. Conclusion: Considering that the urea + urease inhibitor treatment resulted in almost comparable improvements of NUE and baking quality, with the additional benefit of reduced N losses in combination with easy handling, urea + urease inhibitor can be recommended as a viable alternative to both urea alone and ammonium nitrate treatments. This opens up an opportunity for the reduction of N loss in wheat production when use of urea is preferred.     

Effect of dietary calcium or phosphorus deficiency on bone development and related calcium or phosphorus metabolic utilization parameters of broilers from 22 to 42 days of age

This experiment was conducted to investigate the effect of dietary calcium (Ca) or phosphorus (P) deficiency on bone development and related Ca or P metabolic utilization parameters of broilers from 22 to 42 days of age based on our previous study, which indicated that dietary Ca or P deficiency impaired the bone development by regulating related Ca or P metabolic utilization parameters of broilers from 1 to 21 days of age. A total of 504 one-day-old Arbor Acres male broilers were randomly assigned to 1 of 4 treatments with 7 replicates in a completely randomized design, and fed the normal control and Ca- or P-deficient diets from 1 to 21 days of age. At 22 days of age, the broilers were further fed the normal control diet (0.90% Ca+0.35% non-phytate P (NPP)), the P-deficient diet (0.90% Ca+0.18% NPP), the Ca-deficient diet (0.30% Ca+0.35% NPP) or the Ca and P-deficient diet (0.30% Ca+0.18% NPP), respectively. The results showed that dietary Ca or P deficiency decreased (P<0.05) tibia bone mineral density (BMD), bone breaking strength (BBS), ash content, tibia ash Ca content and serum P content on days 28 and 42, but increased (P<0.05) tibia alkaline phosphatase (ALP) activity of broilers on day 42 compared with the control group. Furthermore, the broilers fed the P-deficient diet had the lowest (P<0.05) tibia BMD, BBS, ash content, serum P content and the highest (P<0.05) serum Ca content on day 28 compared with those fed the Ca-deficient or Ca and P-deficient diets. The results from the present study indicated that the bone development and related Ca or P metabolic utilization parameters of broilers were the most sensitive to dietary P deficiency, followed by dietary Ca deficiency or Ca and P-deficiency; dietary Ca or P deficiency impaired the bone development possibly by regulating serum Ca and P contents as well as tibia Ca content and ALP activity of broilers from 22 to 42 days of age.     

Effect of organic amendment amount on soil nematode community structure and metabolic footprints in soybean phase of a soybean-maize rotation on Mollisols

It has been well documented that organic amendment affects soil nematode community structure. However, little is known about the effect of organic amendment amount on soil nematodes. To assess the effect of the amount of organic amendments on soil nematode community structure and metabolic activity, the community composition, abundance, and metabolic footprints of soil nematodes were determined in a long-term field experiment with various amounts of organic amendment in Northeast China. Fertilization treatments included an unfertilized control (CK), chemical fertilizer without manure amendment (OM₀), manure applied at 7.5 Mg ha^-1 plus chemical fertilizer (OM₁), and manure applied at 22.5 Mg ha^-1 plus chemical fertilizer (OM₂). A total of 46 nematode genera were found. Treatments with the largest amount of organic amendment had the smallest number of plant parasite genera (5), but a largest number of dominant genera (7). Soil nematodes, bacterivores, and fungivores were the most abundant in OM₂, followed by OM₁, and the lowest in OM₀ and CK. Organic amendment increased the enrichment index (EI), and the large amount of organic amendment increased the metabolic footprints of bacterivore (Baf) and fungivore (Fuf) and enrichment footprint (Ef). The relationships between Baf (or Fuf) and the increases in soil organic carbon (ΔSOC) and total nitrogen (ΔTN) were stronger than those of bacterivore (or fungivore) abundance with ΔSOC and ΔTN, except for the relationship between bacterivore abundance and ΔSOC. The EI and Ef were positively correlated with ΔSOC and ΔTN. These findings suggest that the amount of organic amendment affects soil nematode activity and function at entry levels in soil food web, and that metabolic footprints of soil nematodes may be better indicators than their abundances in assessing their relationships with soil nutrients.     

睡莲叶片胎生发育转录组分析

睡莲叶片胎生现象是繁育途径的重要补充,对种群的传播、扩散和生态环境的适应性有重要作用。通过转录组测序技术筛选和分析睡莲叶片胎生现象相关的代谢路径和调控基因,为深入认识睡莲叶片胎生发育的分子机制提供参考。以叶片具有胎生现象的‘小花睡莲’（X）和叶片无胎生现象的‘蓝星睡莲’（L）为材料,利用RNA-Seq技术对叶片4个发育阶段的叶脐部分进行生物信息学分析。分析对照（L）和样品（X）叶片不同发育阶段测序结果：筛选出的差异表达基因（DEGs）中,34 909个基因（48.65%）表达上调,36 850个基因（51.35%）表达下调。DEGs分析显示,随着叶片的发育,X和L上调基因和下调基因数均呈增加趋势。对L1-vs-X1、L4-vs-X4阶段的GO和KEGG功能富集分析表明,DEGs主要富集在质膜和膜相关成分、胞外区域、细胞壁等相关的细胞组分中,涉及到代谢过程、生物合成和应急响应等;Pathway代谢通路表明,DEGs主要参与到植物激素信号转导、苯丙烷类生物合成、氨基酸类代谢、类黄酮生物合成、甘油磷脂类代谢以及细胞周期相关等过程。对DEGs进一步分析,克隆出了4个可能参与睡莲叶片胎生发育的转录因子。     

一氧化氮合成酶抑制剂对宰后成熟过程中牦牛肉品质的影响

【目的】研究一氧化氮对宰后牦牛肉品质的影响,为牦牛肉品质改善提供理论依据。【方法】以3—5岁去势甘南牦牛肉为材料,取其背最长肌,剔除筋膜、脂肪等,切成大小均匀的薄片（8 cm×8 cm）,用20 G针均匀穿刺,分别采用去离子水（对照组）和1、10、100 mmol·L ^-1一氧化氮合成酶（NOS）抑制剂（N-硝基-L-精氨酸甲酯盐酸盐）在4℃条件下1﹕1（V/m）浸泡肉样1 d,然后在4℃条件下成熟,测定成熟期间（0、1、3、5和7 d）NOS活性与一氧化氮含量、肌原纤维小片化指数（MFI）、总巯基含量、羰基含量、pH、色度等指标。【结果】NOS抑制剂处理后的牦牛背最长肌NOS活性和一氧化氮含量显著降低,成熟第7天时,处理组的NOS活性分别比对照组低30.9%、43.6%、74.7%,一氧化氮含量分别比对照组低4.7%、12.5%、21.5%。处理后的牦牛肉pH显著降低,第7天时,处理组分别比对照组低0.8%、5.7%、15.2%,其中10和100 mmol·L ^-1 NOS抑制剂处理组显著低于对照组。处理显著降低了牦牛肉羰基含量,成熟第7天时,处理组分别比对照组低4.1%、19.0%、22.2%。此外,处理组MFI显著上升,成熟第7天时,处理组分别比对照组低31.1%、23.3%、9.6%。处理组牦牛肉总巯基含量显著上升,第7天时,对照组比NOS抑制剂处理组分别低3.2%、3.7%、2.7%。成熟过程中,NOS抑制剂处理使肉色a ^*值显著降低,肉色L ^*值显著升高,第7天时,处理组的肉色a ^*值分别比对照组低7.1%、40.2%、30.7%,肉色L ^*值分别比对照组高1.1%、2.0%、1.1%。【结论】一氧化氮促进宰后牦牛肉蛋白质氧化,抑制牦牛肉嫩化,使肉色L ^*值降低,a ^*值升高,对宰后牦牛肉的品质产生负面影响,而NOS抑制剂能降低肌肉中NOS活性。     

改性尿素追施对冬小麦和夏玉米季氮素挥发和淋溶的影响

以NBPT(N-丁基硫代磷酰三胺)和DMPP(3,4-二甲基吡唑磷酸盐)为复合抑制剂,利用转鼓喷涂工艺,开发出新型复合型抑制剂涂覆尿素肥料,采用扫描电镜和能谱仪分析其涂覆效果。通过田间试验系统对比评价了追施不同氮肥对调控氮素的特征效果。试验设置5个处理:(1)不施氮肥(CK);(2)农民习惯追施尿素(CU);(3)优化追施尿素(CUU);(4)优化追施抑制剂涂覆尿素(CUY1);(5)优化追施抑制剂涂覆尿素(CUY2)。在夏玉米喇叭口期、冬小麦拔节期追施氮肥后的15天内进行田间原位连续动态观测。电镜和能谱结果表明,复合抑制剂均匀涂覆于尿素表面,形成薄而致密、光滑的涂覆层,该涂覆层均匀分布有磷和硫2种元素,表明复合抑制剂与尿素已有效结合。田间试验结果表明,在同等优化施氮量下与普通尿素相比,夏玉米和冬小麦季追肥后CUY1和CUY2处理氨挥发分别降低55.19%,32.15%和52.46%,39.43%。夏玉米季追肥后,0-20 cm土层CU、CUU处理土壤硝态氮含量于第5天达到峰值,到后期已显著低于CUY1、CUY2处理,CUY2处理稳定硝态氮的效果更好。冬小麦季追肥后,0-20 cm土壤硝态氮含量CU、CUU处理分别在第5,3天达到峰值,CUY1、CUY2处理于第11天达到峰值后,硝态氮含量已显著高于相同施氮量的CUU处理。在保证产量和净收益的同时,抑制剂涂覆尿素显著降低了追施氮素的氨挥发和淋溶损失浓度,其中冬小麦季CUY1处济效益较好,夏玉米季CUY2调控氮素的效果最佳,减少向下淋溶的效果明显。