Effect of farm management on topsoil organic carbon and aggregate stability in water: A case study from Southwest England,UK

There are few reliable data sets to inspire confidence in policymakers that soil organic carbon (SOC) can be measured on farms. We worked with farmers in the Tamar Valley region of southwest England to select sampling sites under similar conditions (soil type, aspect and slope) and management types. Topsoils (2–15 cm) were sampled in autumn 2015, and percentage soil organic matter (%SOM) was determined by loss on ignition and used to calculate %SOC. We also used the stability of macroaggregates in cold water (WSA) (‘soil slaking’) as a measure of ‘soil health’ and investigated its relationship with SOC in the clay‐rich soils. %SOM was significantly different between management types in the order woodland (11.1%) = permanent pasture (9.5%) > ley‐arable rotation (7.7%) = arable (7.3%). This related directly to SOC stocks that were larger in fields under permanent pasture and woodland compared with those under arable or ley‐arable rotation whether corrected for clay content (F = 8.500, p < .0001) or not (F = 8.516, p < .0001). WSA scores were strongly correlated with SOC content whether corrected for clay content (SOC_adj R² = .571, p < .0001) or not (SOC_unadj R² = 0.490, p = .002). Time since tillage controlled SOC stocks and WSA scores, accounting for 75.5% and 51.3% of the total variation, respectively. We conclude that (1) SOC can be reliably measured in farmed soils using accepted protocols and related to land management and (2) WSA scores can be rapidly measured in clay soils and related to SOC stocks and soil management.     

病原微生物荚膜多糖的生物学功能

荚膜多糖（capsular polysaccharide，CPS）是一种广泛存在于细菌、支原体、部分真菌等菌体表面的碳水化合物。同时，荚膜多糖有助于菌体抵抗干燥和低温等不利环境，并通过在菌体表面形成物理屏障阻碍宿主补体的杀伤与吞噬作用。在长期多种应激-压力环境下，病原菌已进化出多种免疫逃避机制并促进宿主感染；在非病原微生物中，荚膜多糖可正向调节宿主免疫作用，并拮抗机体免疫因子，保护宿主免受病原菌引起的炎症性疾病。本文将结合本团队的相关研究工作，对荚膜多糖的结构、合成调控机制、生物学功能、免疫逃避机制和致病机制，特别是荚膜多糖正向调节宿主免疫系统及其应用潜力等方面作一综述，为病原菌致病机制的研究和疫病的有效防控提供参考依据。     

鸡Ii结合Rab5a和Rab7b分子的分析

本研究旨在探明鸡恒定链（invariant chain，Ii）与内吞体转运蛋白Rab5a和Rab7b结合的结构域和在细胞内共定位的特征。首先，用PCR和基因突变技术将Ii胞浆区与跨膜区[Ii_{（Cyt-Tra）}]、Ii CLIP （class Ⅱ-associated invariant chain peptide）-三聚体区[Ii_{（CLIP-TRIM）}]和Ii突变体[Ii_{（M81-87aa）}、Ii_{（M91-99aa）}和Ii_{（M81-99aa）}]分别插入pET-32a和pEGFP-C1构建相应的原核和真核重组质粒。其次，将构建的含有绿色荧光蛋白的重组质粒与实验室保存的含有红色荧光Rab5a和Rab7b的重组质粒共转染至人胚胎肾细胞系293 T，观察它们的共定位。将构建的原核重组质粒进行表达和纯化，最后用拉下法和免疫印迹检测Ii与Rab5a和Rab7b的结合域。结果表明，成功构建Ii结构域及Ii突变体的重组质粒。Ii_{（Cyt-Tra）}及Ii突变体均能与Rab5a和Rab7b在细胞内共定位，而Ii_{（CLIP-TRIM）}与空载体却不能。Ii的胞浆区和跨膜区是与Rab5a和Rab7b结合的功能结构域，而不是CLIP与三聚体区。综上所述，鸡Ii与Rab5a和Rab7b共定位和结合的区域是其胞浆区和跨膜区，而不是内质网腔区。这些结果提示Rab分子参与了Ii在胞内细胞器的转运机制，为进一步研究Ii及其载体在细胞内的转运机制和功能提供了新的途径。     

食用菌多糖抗运动疲劳研究进展

采用文献资料法对食用菌多糖抗运动疲劳的研究进展情况进行了研究。结果表明:食用菌多糖提取方法不同而食用菌多糖的提取率也不相同,超声波法+复合酶法及微波法提取食用菌多糖提取率较高,2种方法科学合理的结合提取食用菌多糖以及不同产地、品种和不同部位提取率是未来学者们需要研究的领域;目前,只是对极少部分食用菌多糖抗运动疲劳进行了研究,研究对象(动物)、模型、指标、评价单一而没有确定最佳剂量的时间而没确定的量。为此,提出了未来应加强和重视食用菌多糖抗疲劳运动多食用菌、多对象(尤其是人)、多模型、多指标、多评价、最佳剂量的研究以及量-效、构-效关系的研究建议。     

绵羊WNT5A基因克隆及其组织表达分析

WNT5A(Wnt family member 5A)参与了多种细胞的增殖、凋亡和分化等生物学过程,在乳腺形态发生、毛囊发育等方面发挥了重要作用。该试验利用RT-PCR获得绵羊WNT5A基因的CDS区,分析WNT5A蛋白的结构特征并利用RT-qPCR检测WNT5A基因在9个组织中的表达情况。绵羊WNT5A基因的CDS区全长1062 bp,编码353个氨基酸。该蛋白的二级结构主要以α-螺旋和无规则卷曲为主,β转角、延伸链贯穿于整个蛋白质结构中。String分析结果表明,WNT5A与卷曲蛋白受体、低密度脂蛋白相关蛋白和受体酪氨酸激酶有相互作用。RT-qPCR研究结果表明,WNT5A基因表达具有组织特异性及品种特异性。WNT5A基因在绵羊心脏、肝脏、肺脏、脾脏、肾脏、卵巢、背最长肌、乳腺和皮肤9个组织中均广泛表达,其中在皮肤中的表达量高于其他组织(P<0.05),而在脾脏中表达量较低。它在甘肃高山细毛羊皮肤、乳腺、背最长肌、肾脏、肺脏、脾脏和肝脏中的表达量高于小尾寒羊(P<0.05),而在甘肃高山细毛羊卵巢中的表达量低于小尾寒羊(P<0.05),在心脏中该基因的表达量无差异(P>0.05)。该结果为深入研究绵羊WNT5A基因的功能提供了重要依据,同时也丰富了绵羊基因组内容。     

The Identification of QTL Associated with Cotton Fruit Branch Length Suitable for Mechanized Harvest Utilizing BSA-seq

[Objective] This study aims to identify quantitative trait loci (QTLs) associated with cotton fruit branch length by using the combination of bulked-segregant analysis (BSA) and next-generation sequencing (NGS) method. [Method] In this study, the cotton F₂ segregating population was developed with the short branch line Sujimian 125 and long-branch variety Sikang 1 as cross parents. According to the average internode length of fruit branches in middle, extreme individuals in F₂ population were divided into two groups to generate the bulked DNA samples. The whole-genome resequencing of two DNA bulks was applied to analyze the single nucleotide polymorphism (SNP) and insertion-deletion (InDel) between two groups, and the fruit branch internode length related QTLs were detected using Euclidean distance (ED). [Result] With SNP data obtained from sequencing, a 0.8 Mbp range associated region on chromosome A3 was identified; with InDel data obtained from sequencing, a 1.09 Mbp range associated region on chromosome A3 was identified. Two regions overlapped, and the overlapped range was 0.77 Mbp. [Conclusion] This result suggested that the difference between I-type fruit branch and zero-type was due to different genetic locus and pattern rather than dosage effect of the same gene.     

鸡腿菇多糖减轻运动疲劳的机理分析

对鸡腿菇多糖的抗氧化活性进行了试验,试验表明,鸡腿菇多糖对·OH和DPPH·都具有一定的清除活性,且清除率与多糖的浓度成正比。这说明鸡腿菇多糖能够防止人体细胞膜过氧化损伤,减轻运动员的疲劳。     

寄主植物中抑制十字花科黑腐病菌Ⅲ型分泌系统小分子化合物的鉴定

 寻找抑制植物病原菌III型分泌系统的植物源活性小分子化合物,是研发生物安全农药的重要途径之一。本研究采用水煮提取法从十字花科黑腐病菌寄主植物满身红萝卜中提取分离活性小分子化合物,利用高效液相-质谱联用解析出活性物质的单体结构。然后用荧光素酶基因luxAB构建融合报告系统以及定量PCR检测活性物质对十字花科黑腐病菌III型分泌系统的抑制效果,最后采用剪叶接种和压渗接种的方法研究活性小分子物质对十字花科黑腐病菌的生防作用。研究表明,植物鞘氨醇和二氢鞘氨醇对十字花科黑腐病菌III型分泌系统基因的转录表达有一定程度的抑制作用,但是对I、II、IV型分泌系统基因的表达没有明显的抑制作用。植物鞘氨醇在XCM1上影响菌的生长,而二氢鞘氨醇不影响菌的生长。同时,还发现这两种物质能显著降低Xcc在寄主植株满身红萝卜上的病害症状以及能够使Xcc在非寄主植物辣椒上引起过敏反应的能力丧失。该研究结果为深入研究小分子化合物对十字花科黑腐病菌III型分泌系统的作用机制及后续开发植物源抑制剂提供了一定的理论依据。     

Effect of DNA methylation of miR-30a-5p promoter region on hepatic injury induced by homocysteine

AIM: To explore the role of DNA methylation of microRNA-30a-5p(miR-30a-5p) promoter region in hepatic injury. METHODS: Four-week-old normal mice and cystathionine β-synthase (CBS) single gene knockout mice were used and divided into normal (CBS^+/+, n=12) group and single gene knockout (CBS^+/-, n=12) group, and the mice were fed with high methionine diet for 8 weeks. HL-7702 hepatic cells were routinely cultured in vitro and divided into control group, homocysteine (Hcy) group and Hcy+5-azacytidne (AZC) group. Serum Hcy, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were measured by automatic biochemical analyzer. The levels of ALT and AST in the cells culture medium were determined by the microplate method. Hepatic injury in the mice were observed with HE staining. Cell viability staining was used to measure the viability of hepatocytes. RT-qPCR was used to detect the expression of miR-30a-5p in the liver tissues and hepatocytes. The correlation between the expression of miR-30a-5p and serum ALT and AST levels was analyzed by Pearson correlation analysis. DNA methylation level of miR-30a-5p promoter region in the liver tissues and hepatocytes was detected by nested landing methylation-specific PCR (nMS-PCR). RESULTS: Compared with the CBS^+/+ mice, the serum levels of Hcy, ALT and AST in the CBS^+/- mice were significantly increased (P < 0.05). HE staining showed the hepatocyte swelling and nuclear fragmentation and dissolution. The expression level of miR-30a-5p in the liver tissues was decreased (P < 0.01). Besides, the expression level of miR-30a-5p in the mice was negatively correlated with serum ALT and AST levels (r²=0.4557, P=0.0003, r²=0.4626, P=0.0003), and the DNA methylation of miR-30a-5p promoter region was increased (P < 0.01). In the HL-7702 cells, compared with control group,the ALT and AST levels were increased in Hcy group (P < 0.05, P < 0.01), and the cell viability was remarkablely decreased. DNA methylation of miR-30a-5p promoter region was increased (P < 0.01), which decreased after treated the cells with AZC (P < 0.05), while the expression level of miR-30a-5p in the cells was increased (P < 0.05). CONCLUSION: Hypermethylation of miR-30a-5p promoter region may play an important role in hepatic injury.     

新型锌制剂对虹鳟生长及免疫功能的影响

为研究纳米锌及纳米锌多糖复合体对虹鳟生长及免疫功能的影响,选取平均体质量(120.0±3.0) g的虹鳟300尾,随机分成5组,每组3个平行,每个平行20尾,按1μL/g进行尾部肌肉注射纳米锌及纳米锌多糖复合体溶液,含量分别为1000、3000 mg/kg,试验周期为10 d。试验结果显示,纳米锌及纳米锌多糖复合体可不同程度提高虹鳟特定生长率(P>0.05)。1000 mg/kg纳米锌多糖复合体组虹鳟血液NBT阳性细胞数量百分比在第3 d最高,达22.3%(P<0.05);3000 mg/kg纳米锌多糖复合体组白细胞吞噬能力在第6 d最强(P<0.05)。3000 mg/kg纳米锌组虹鳟血清杀菌能力第3 d最高(19.4%),而3000 mg/kg纳米锌多糖复合体组血清杀菌能力第6 d最高,达32.43%(P<0.05)。第3 d,1000 mg/kg纳米锌多糖复合体组过氧化氢酶活性、一氧化氮合成酶活性分别为26.39、43.38 U/mL (P<0.05);第6 d,超氧化物歧化酶、酸性磷酸酶活性最高,分别为29.91 U/mL、201.4 U/L(P<0.05),微量丙二醛浓度最低,为3.19 nmol/mL。试验结束后通过杀鲑气单胞菌攻毒感染,7 d内观察虹鳟累积死亡率,1000 mg/kg纳米锌多糖复合体组累积死亡率仅30%。由试验结果可知,纳米锌和纳米锌多糖复合体均能对虹鳟免疫功能产生促进作用,以1000 mg/kg纳米锌多糖复合体效果最佳。