猪圆环病毒3型TaqMan-MGB荧光定量PCR方法的建立及应用

为建立猪圆环病毒3型(PCV3)荧光定量PCR检测方法,本研究根据GenBank中PCV3基因序列设计特异性引物和探针,经过反应体系和条件优化,建立了特异性检测PCV3的TaqMan-MGB荧光定量PCR方法。该检测方法在4.78×10~1拷贝/μL～4.78×10~9拷贝/μL质粒标准品范围内均有良好的线性关系;该方法特异性试验结果显示,其与多种常见猪病病毒均无交叉反应,特异性良好;本研究建立的方法敏感性是常规PCR方法的100倍,敏感性较高;批内批间重复性试验变异系数均小于2.3%,重复性良好。对临床样品的检测结果显示,该方法对PCV3的检出率高于常规PCR方法,并且PCV3阳性样品多存在混合感染情况。该方法的建立为PCV3的实验室诊断及流行病学调查提供了快速、准确的检测手段。     

Variation among stallions in sperm quality after single layer centrifugation

Although single layer centrifugation (SLC) selects robust spermatozoa from stallion semen, the effect of individual variation has not been studied in detail. The objective of this study was to determine the variation among stallions in the effects of SLC on sperm quality during cooled storage for up to 48 hr. Semen samples from seven stallions (18 ejaculates) were split, with one portion being used for SLC and the other serving as a control (CON). Sperm quality (kinematics, reactive oxygen species (ROS) production, membrane integrity (MI) and chromatin integrity) were analysed at 0, 24 and 48 hr using computer-assisted sperm analysis and flow cytometry. Sperm quality was better in SLC than in CON at all timepoints, especially chromatin integrity and MI (p < .0001 for both), and some categories of ROS production (e.g. proportion of live hydrogen peroxide negative spermatozoa, p < .0001), but the degree of improvement varied among stallions and type of ROS (p < .05–p < .0001). Total and progressive motility were also better in SLC samples than in CON at 24 and 48 hr (p < .0001), although the effect on sperm kinematics varied. The interaction of treatment, time and stallion was not significant. In conclusion, sperm quality was better in SLC samples than in CON, although there was considerable individual variation among stallions. The improvement in sperm quality, particularly in chromatin integrity, was clearly beneficial, and therefore the use of this technique would be warranted for all stallion semen samples.     

杨树溃疡病病原的多重PCR检测技术

利用真菌通用引物ITS1/ITS4,EF1-728F/EF1-986R对4种杨树溃疡病病原菌株和环境样本的核糖体DNA内部转录间隔区ITS序列和转录延伸因子EF-1α基因序列分别进行普通和多重PCR检测,再进行测序比对分析。结果表明:退火温度为55.6 ℃,各引物终浓度为0.2 μmol·L^-1,可以成功地扩增出菌株和环境样本的目的条带,并通过测序比对鉴定出多种来自培养和环境病害组织中的溃疡病病菌,多重PCR能够检测到1 ng的基因组DNA。研究结果将为建立溃疡病病原多重PCR鉴定技术和以环境溃疡病病害样本为直接检测鉴定对象的高通量的基因芯片检测方法奠定基础。     

Occurrence of methicillin-resistant staphylococci in the pig-production chain in Ibadan,Nigeria

Staphylococcus species colonises humans and animals and is a major food contaminant with public health significance. Here, we assessed the occurrence of methicillin-resistant staphylococci (MRS) in the pig-production chain in Ibadan, Nigeria. Nares of 120 pigs and 10 farmers were sampled with sterile swabs whilst 54 pork samples were collected from a retail slaughterhouse. Staphylococcus species were isolated using enrichment, cefoxitin–aztreonam selective broth and Mannitol salt agar. Isolates were tested for susceptibility to cefoxitin (30 μg), oxacillin (1 μg) and vancomycin (30 μg). Methicillin-resistant staphylococci isolates were characterised using conventional biochemical tests. From 184 samples, 364 staphylococcal isolates were obtained. Amongst the 54 pork samples, 44.0% were contaminated with Staphylococcus species. Overall, 9 (2.5%) MRS were obtained and presumptively identified as Staphylococcus xylosus (n = 3), Staphylococcus sciuri (n = 3), Staphylococcus warneri (n = 2) and Staphylococcus cohnii (n = 1). There was no relationship between the prevalence of MRS between pigs and pig handlers in the farms, but Farm 2 had the highest frequency of 66.7% (p < 0.05). Piglets had the highest prevalence of 66.7% (p < 0.05) whilst MRS was absent in workers and pork samples. This study raises concerns about the cross-contamination of staphylococci in the food chain. Constant surveillance is imperative to ensure food safety.     

安徽地区禽源临床样品药敏试验结果分析

对2015-2017年安徽地区送检至安徽省兽医临床诊断中心的365份禽源临床样品的药敏试验结果进行分析,结果显示,10种常用抗生素检测中以2、3种可推荐的抗生素为主,在可推荐抗生素中头孢噻肟比例最高,达到70.14%,其次是阿米卡星和多西环素,分别为60.27%和49.04%,而阿莫西林、氟苯尼考和庆大霉素的比例均低于5%;在首选抗生素中头孢噻肟、阿米卡星和多西环素的比例分别为38.36%、30.96%和16.36%。氟苯尼考、庆大霉素、左氧氟沙星和头孢噻肟作为可推荐药物的比例逐年升高,阿莫西林、阿米卡星的比例则逐年降低,表现出一定的规律性。本分析结果对指导安徽地区禽病临床治疗用药具有重要的参考意义。     

Multi-element analysis of soils and sediments by wavelength-dispersive X-ray fluorescence spectrometry

Soil and sediment reference materials were used to calibrate and evaluate an analytical method for the determination of major (Si, Al, Fe, Mg, Ca, Na, K, Mn, P, Ti) and trace elements (As, Ba, Cd, Co, Cr, Cu, Ga, Mo, Mb, Ni, Pb, Rb, S, Sb, Sn, Sr, Th, U, V, Y, Zn, Zr) by sequential wavelength X-ray fluorescence spectrometry. Samples were prepared as pressed pellets and analysis was done with a total measuring time of thirty minutes per sample. Special attention was given to the selection of the thirty reference materials used for calibration of the spectrometer. Another set of eleven RM (reference materials) was analyzed for the evaluation of accuracy. Detection limits for trace elements (1-2 mg kg^-1) are adequate both for geochemical and environmental purposes, except for Cd and Sb. Accuracy for trace elements falls within the expected interval of certified or recommended values in most cases, but for some major elements, like SiO₂, some results showed discrepancies, evidencing difficulties associated with the determination of light elements in complex matrices. But when quality criteria proposed by mapping programs are applied to the results, their requirements are fulfilled. Both instrumental precision, obtained by twelve sample replicate analyses, and analytical precision, considering also sub-sampling and pellet preparation, lie between the limits of the Horwitz expression, except at concentrations close to the detection limits.     

Spiking-Hybrid方法与机器学习结合的冬小麦LAI反演

【目的】 准确地反演叶面积指数（Leaf Area Index,LAI）对小麦生长诊断和管理调控具有重要意义。目前机器学习方法被广泛应用于作物参数反演,但农业领域原始数据获取成本高,机器学习模型在LAI反演中面临训练数据不足、过拟合等问题。【方法】 文章基于遥感辐射传输PROSAIL模型模拟数据结合实测数据,采用Spiking-Hybrid方法构建混合样本集,再利用随机森林（Random Forest,RF）和偏最小二乘回归（Partial Least Squares Regression,PLSR）机器学习算法来反演叶面积指数。将Spiking-Hybrid方法与数值优化的PROSAIL反演方法、传统混合方法和经验机器学习方法等3种常用的植被性状估计方法进行对比分析。【结果】 Spiking-Hybrid方法在不同小麦生育期的LAI反演中展现出优于其他方法的效果,即使选择不同条数、不同生长地域的实测抽样样本,Spiking-Hybrid方法一直表现出更好的准确度和稳健性。当抽取实测样本为40~60条时模型精度最高,在挑旗期使用60份样本时达到了最佳测试精度（R2=0.85,RMSE=0.78）。【结论】 当实测样本十分有限时,Spiking-Hybrid方法比基于模拟数据的机器学习算法具有更好的反演精度,并且Spiking-Hybrid方法在极少的实测样本量时也能发挥很好的作用。     

生物药剂复配对棉花黄萎病防治及生长发育的影响

【目的】研究生物药剂复配对棉花黄萎病防治效果及生长发育的影响,为棉花植株健康生长提供理论依据。【方法】于2022年进行大田试验,选用棉花品种为新陆中42号。药剂以80%乙蒜素乳油药液、亚磷酸钾、谷胱甘肽为基础,分别为复配抗病毒专用型助剂(T₁)、复合微生物菌肥(T₂)、15%噁霉灵(T₃)、5%辛菌胺醋酸盐(T₄)、25%吡唑醚菌酯(T₅),分析不同药剂对棉花黄萎病防治效果,农艺性状及产量的影响。【结果】各处理对棉花病害防治效果显著,对棉花生长表现出一定的促进作用,增加棉花株高、果枝数和蕾铃数。其中T₂处理较T₁和T₃处理对棉花黄萎病防治效果提高19.99%、23.34%,T₁、T₂处理较CK处理铃数增加1.8个、2.67个。T₂处理的籽棉产量为6 104.86 kg/hm²,较其他处理产量最高并差异显著。【结论】滴施复合微生物菌肥+80%乙蒜素乳油+亚磷酸钾+谷胱甘肽(T₂)可提高黄萎病防治效果,增加蕾数铃数和单株结铃数,从而显著增加棉花产量。     

兽医科学研究中的样品采集方法及其最新进展

样品采集是兽医科学研究中必不可少的环节。以中华人民共和国农业行业标准《动物疫病实验室检验采样方法》为基础,结合临床实践和研究经历,介绍了基于不同研究目的和内容的样品采集种类、数量和操作,以及样品收装、保存和处理方法,重点概述了国内外关于采样方法的最新进展,从而为今后的兽医科学研究提供参考。