Quantitative studies of the distribution pattern for <Emphasis Type="Italic">Salmonella</Emphasis> Enteritidis in the internal organs of chicken after oral challenge by a real-time PCR

This research was undertaken to identify and understand the regular distribution pattern for Salmonella Enteritidis (S. enteritidis) in the internal organs of chicken after oral challenge over a 3 wk period. We used a real-time, fluorescence-based quantitative polymerase chain reaction (FQ-PCR) to detect genomic DNA of S. enteritidis in the blood and the internal organs, including heart, liver, spleen, kidney, pancreas, and gallbladder, from chicken after oral challenge at different time points. The results showed that the spleen was positive at 12 h post inoculation (PI), and the blood was at 14 h PI. The organism was detected in the liver and heart at 16 h PI, pancrea was positive at 20 h PI, and the final organ to show a positive results were the kidney and gallbladder at 22 h PI. The copy number of S. enteritidis DNA in each tissue reached a peak at 24 h–36 h PI, with the liver and spleen containing high concentrations of S. enteritidis, whereas the blood, heart, kidney, pancreas, and gallbladder had low concentrations. S. enteritidis populations began to decrease and were not detectable at 3 d PI, but were still present up to 12 d PI in the gallbladder, 2 wk for the liver, and 3 wk for the spleen without causing apparent symptoms. The results showed that the liver and spleen may be the primary sites for S. enteritidis setting itself up as a commensa over a long time after oral challenge. Interestingly, it may be the first time reported that the gallbladder is a site of carriage for S. enteritidis over a 12 d period. This study will help to understand the mechanisms of action of S. enteritidis infection in vivo.     

植物细胞壁伸展蛋白研究述评

结构蛋白是细胞壁的重要组成成分.最早发现的细胞壁结构蛋白是伸展蛋白,它在初生壁中约占壁干质量的1%～15%.广义的伸展蛋白是一类富含羟脯氨酸的糖蛋白(HRGP),狭义的伸展蛋白则特指具有Ser-Hyp4重复模体的HRGP分子.以往的研究发现伸展蛋白主要功能是控制细胞的正常伸展,增强细胞壁的机械强度.近年来在拟南芥中进行的伸展蛋白基因缺失突变研究结果显示,伸展蛋白也参与细胞壁的初始形成过程,这是不同于以往对细胞伸展蛋白认识的新发现.伸展蛋白翻译后修饰包括脯氨酸残基羟基化、羟脯氨酸与丝氨酸残基糖基化,在过氧化物酶催化下,形成分子间与分子内交联,通过直链和支链连接进行分子组装.由于伸展蛋白是细胞壁结构蛋白的主要组成成分,研究伸展蛋白的结构和功能对更好地了解细胞壁结构及其组装具有重要意义.     

高磷土壤减量施磷对果蔗磷肥利用效率和土壤酶活性的影响

生产中为了追求高收益,果蔗种植中磷肥过量投入现象普遍,造成肥料效率降低和土壤肥力失衡等问题。本研究在广东湛江高磷红壤区采取田间定位试验（初始有效磷含量为234.80mg/kg）,研究磷肥减量100%（P0）、50%（P1）、20%（P2）和当地常规施磷（CK,600kg P₂O₅/hm²）处理下,果蔗磷肥利用效率以及土壤酶活性的变化特征。结果表明,经过连续2年试验后,果蔗产量、糖分含量、株高和茎径等品质性状均表现为P2＞CK＞P1＞P0。P2处理磷肥利用率最高（32.09%）,P1处理最低（28.08%）;农学效率为P2＞P1＞CK;磷肥偏生产力为P1＞P2＞CK。随着施磷水平的降低,α-葡萄糖苷酶和与氧化还原相关的过氧化物酶、多酚氧化酶等酶的活性提高,β-葡萄糖苷酶、纤维二糖苷酶、乙酰氨基葡萄糖苷酶以及磷酸酶等水解酶活性均呈现下降趋势;与氮转化相关的亮氨酸氨肽酶和脲酶活性均以P2处理最低,P0处理最高。此外,土壤酶活性与土壤养分含量显著相关（P＜0.05）。综合果蔗产量、品质、磷肥利用效率以及土壤酶活性及其对生长影响,较常规施磷减量20%（P2）是该地区果蔗的适宜用量。     

春玉米、冬小麦涌泉灌溉与垄膜沟种的组合应用试验

涌泉灌溉用于大田作物主要问题是流量小,沟、畦横断面大,水流在田间很难向前推进。为此将其与垄膜沟种技术组合,缩小过水横断面,减小或杜绝侧渗,提高水流推进能力,这样可最大限度地减少灌水器(稳流器)数量,改善灌水质量,提高田间土壤水分的均匀度,进而为涌泉灌溉用于大田作物提供了可能性。采用涌泉灌溉配套垄膜沟种耕作方式,提高了降水的有效利用率,减少了灌水量与灌水次数、减少了棵间土壤水蒸发、农田耗水比一般大田灌溉节省28.3%。由于灌水量可控,比一般地面灌溉节约28%～47%。     

Research on the Effect of Plant Combination Types on the Shear Strength of the Root-soil Composite System of Alpine Grassland in the Source Region of the Yellow River北大核心CSCD

In this study,an alpine grassland in Henan County,Qinghai Province,in the source region of the Yellow River,was selected as the study area. The shear strength of root-soil composite system characteristics of 6 different plant combination types of grassland were explored by field investigation and sampling and indoor tests,which aimed to provide a theoretical basis for preventing and controlling soil erosion and shallow landslide caused by grassland degradation. The test results showed that the shear strength of root-soil composite system of 6 different combinations was a increasing trend with the decrease of altitude. Namely,the shear strength of the root-soil composite system of Stipa purpurea Griseb. + Kobresia pygmaea C. B. Clarke at the top of the sunny slope was 27.76 kPa and the value of Elymus nutans Griseb. at the bottom of the sunny slope was 37.53 kPa. The reasons why the shear strength of 6 kinds of combinations varied from large to small with the decrease of altitude were related to their density,moisture content,root content and dry weight of roots in the root-soil composite system samples. That is,the root content of composite system at the top,middle and bottom of the sunny slope were 6.2%,5.5% and 16.2%,respectively. The values at the top,middle and bottom of the shady slope were 8.0%,11.4% and 31.6%,respectively. © 2019 China Agricultural University. All rights reserved.     

凤仙花植株乙醇浸提液和固体粉剂对瘤胃体外发酵代谢参数的影响

本研究旨在分析凤仙花整株制备的固体粉剂和乙醇浸提液对瘤胃体外代谢参数和降甲烷效果的影响。采集装有永久性瘤胃瘘管的牛瘤胃液,以稻草粉、玉米粉和黄豆粉为人工饲料,通过体外瘤胃模拟培养法,研究了固体粉剂和乙醇浸提液不同添加量(0.5%,1.0%和2.5%)对甲烷和二氧化碳气体产生以及瘤胃发酵代谢参数挥发性脂肪酸(VFA)和微生物蛋白(MCP)等影响。结果表明,凤仙花固体粉剂处理在瘤胃发酵中总产气量最高,其次为乙醇浸提液,莫能菌素处理最低(P＜0.05)。凤仙花和莫能菌素处理均能降低甲烷生成,其中固体粉剂处理效果最明显,仅有微量甲烷。莫能菌素处理中二氧化碳含量最低,凤仙花所有处理显著提高二氧化碳含量。莫能菌素和凤仙花降低氨态氮(NH₃-N)含量,随着凤仙花添加量增加,NH₃-N降低更明显。莫能菌素处理中MCP含量最低,凤仙花所有处理都高于莫能菌素和对照,固体粉剂处理的MCP提高效果最明显。莫能菌素处理降低乙酸和总挥发性脂肪酸含量,提高丙酸含量。凤仙花处理不同程度提高瘤胃中乙酸、丙酸和丁酸含量,总挥发性脂肪酸平均比对照高12.9%和20.2%。莫能菌素和凤仙花处理都降低乙酸/丙酸。在体外培养条件下,凤仙花明显降低甲烷生成,促进NH₃-N向MCP转化,改变了瘤胃代谢模式。     

高产杂交籼稻新组合“特优649”产业化技术研究 I 密度及主要肥料因子对产量的影响

试验采用裂区设计，以肥料为主区，密度为副区，研究高产杂交籼稻新组合“特优649”的密度和氮肥、磷肥、钾肥施用量与产量的关系，结果表明：当密度为37.5万穴/hm2，或株行距为20cm×13.2cm，氮肥施用量为225kg纯氮/hm2，其N，P2O5，K2O的比例为1.0:0.5:0.8时，产量最高，平均达9.24t/hm2，最高达9.36t/hm2。据此提出产量指标为9.0 t/hm2以上的优化农艺措施组合为：每hm2密度37.5万穴，每穴插2粒谷秧，纯氮用量225kg，P2O5用量112.5 kg ，K2O用量180.0kg，其中基肥为猪牛粪22.5t+30kg过磷酸钙；试验还提出了相配套的水分运筹方法。     

Study on the abuse of amantadine in tissues of broiler chickens by HPLC‐MS/MS

To evaluate the residual target tissues for better monitoring of amantadine abuse in broiler chickens, 22‐day‐old commercial Arbor Acres broiler chickens were, respectively, fed with 10, 20, and 40 mg/kg of amantadine for five consecutive days. Plasma, breast, and liver tissue samples from the chickens were collected 0, 4, 16, 24, 48, 96, 144, and 312 h after amantadine withdrawal. The high‐performance liquid chromatography–tandem mass spectrometry method was used to detect the concentrations of amantadine. The highest concentration was found in the chicken liver and it took the longest time for amantadine to vanish by metabolism. In the high‐dose group, amantadine residues were still detected 312 h after amantadine withdrawal. As the amantadine dose increased, amantadine residues in the chicken liver were more slowly to disappear than in other tissues. Even if approximately the same concentration of amantadine residues was found in chicken breast and plasma samples, it took a shorter time before the residues were eliminated. In the medium‐ and high‐dose groups, the concentrations of amantadine residues in chicken liver samples were substantially higher than those in chicken breast and plasma samples, and it took more time to eliminate them. Therefore, the chicken liver can be used as a target tissue to detect illegal use of amantadine.     

垂直轴风力机塔柱结构的分析及优化

为了避免风力机系统的共振而导致的系统损坏和噪声污染,通过系统动力特性分析和动力学响应计算分析,得到了风力机塔柱的低阶固有频率和谐响应的数据,以及风轮和塔柱之间的动态关系与整个系统的动态特性,为结构动态设计以及优化提供科学依据.首先确定对风力机塔柱系统结构动态性能影响最大的模态频率,提取该阶模态频率作为动态优化的目标,最后分析塔柱结构与风轮之间的动态干扰.结果表明：原设计在风轮以设计额定转速160 r/min运行时,其产生的简谐荷载对风力机塔柱具有十分严重的破坏性,通过增加主轴钢管的壁厚并提高其刚度等优化工作,经计算证明,在激振力不变的情况下,第一阶固有频率得到提高,塔柱的各阶固有频率下的最大位移大幅减小,优化效果明显,达到结构动力设计的目的.     

规模化猪场处理废水与化肥配施对小麦氮素吸收利用的影响

规模化猪场处理废水富含植物营养物质,应用于作物生产可实现减少化肥用量和保护环境的双赢。本研究通过田间试验,研究了越冬期不同用量养猪处理废水(30、60、90 m3·hm-2和120 m3·hm-2)和穗期施氮水平(0、30、60 m3·hm-2和90 m3·hm-2)对小麦氮素吸收利用的影响。结果表明,猪场处理废水对小麦具有较好的氮素养分供应作用,拔节期、抽穗期、成熟期叶片SPAD值、植株含氮率都随着污水施用量增加而提高。废水施用60 m3·hm-2以上穗期配施氮90 kg·hm-2的处理花后氮素转移效率、氮素收获指数、氮素籽粒生产效率明显下降。越冬期施用养猪场处理废水60～120 m3·hm-2替代穗期施氮30～60 kg·hm-2,可以满足不同时期小麦氮素营养的需求,并且有较高的氮素积累量和利用效率。