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不同的样本特性和提取方法对获得微生物总DNA的质量有重要影响。文章基于高含固率木质纤维素厌氧发酵物腐殖酸、酚类物质含量高、质地均一性差、微生物浓度低的特点,研究了4种方法提取不同高含固率粪秸厌氧发酵物中微生物总DNA的效果。结果表明,常规的十二烷基磺酸钠法(sodium dodecyl sulfate,SDS)、十二烷基磺酸钠和溴化十六烷基三甲铵结合法(sodium dodecyl sulfate and cetyltrimethyl ammonium bromide,SDS-CTAB)和商业的粪便试剂盒法提取的DNA质量均较差,SDS法和试剂盒法未能获得聚合酶链式反应(polymerase chain reaction,PCR)扩增目的条带,SDS-CTAB法得到的条带较模糊;改进SDS-CTAB法获得的DNA杂质少、纯度高,具有较好的稳定性,A260/A280和A260/A230值分别为1.74~1.86和1.65~1.86,每克样品的DNA浓度在50 ng·μL^-1以上,电泳条带单一齐整、清晰明亮,PCR扩增的目的条带清晰度高,适宜后续分子生物学技术的分析。林格氏液洗脱、聚乙烯吡咯烷酮-40(Polyvinyl Pyrrolidone-40,PVP-40)洗涤液除杂以及裂解液和多种酶联合破壁是改进SDS-CTAB法获得该类专一性样本高质量微生物总DNA的关键步骤。 相似文献
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以进口鱼粉和豆粕为饲料蛋白源,研究了6种蛋白水平(分别为27%、30%、33%、36%、39%和42%)的等能饲料对芙蓉鲤鲫幼鱼增重和肠道、肝脏消化酶活性的影响。结果表明,饲料蛋白水平的增加,显著地提高了鱼体增重率、特定生长率、饲料效率、肥满度(P<0.05),并降低了饵料系数和脏体比,还显著地提高了肠道组织蛋白酶、食糜蛋白酶和GOT及GPT活性(P<0.05)。随着饲料中蛋白水平的上升,肝脏蛋白酶和食糜、肠道组织、肝脏淀粉酶活性无显著性差异(P>0.05)。 相似文献
107.
规模化蛋鸡场病原菌溯源与生物安全防控研究 总被引:1,自引:0,他引:1
细菌病严重威胁蛋鸡健康,以抗生素为主导的细菌病传统防控方式会导致病原菌耐药性严重、鸡蛋药物残留,影响蛋品安全。要保证蛋鸡产蛋期不用抗菌药物而又能生产出"无菌、无抗"的鸡蛋,是国内外技术难题。本团队以规模化蛋鸡场全封闭鸡舍为研究对象,基于PFGE、MLST、全基因组测序等技术,探明了蛋鸡病原菌的种类及基因组特征;对病原菌的耐药性研究表明,蛋鸡病原菌多重耐药严重,依靠药物防控的方式亟待转变;对规模化蛋鸡场细菌溯源研究结果表明,鸡舍生物媒介(鼠、苍蝇等)和非生物媒介(空气、饮水、饲料、鸡粪等)是蛋鸡病原菌的重要传染来源和传播途径;对规模化蛋鸡场生物安全量化评价结果表明,外部和内部生物安全权重高达92.2%。根据溯源和生物安全权重分析结果,提出了在规模化全封闭蛋鸡舍将蛋鸡细菌病从药物防控转变为生物安全防控的新策略;创新了规模化蛋鸡场细菌病防控的系统技术,实现蛋鸡规模养殖整个产蛋期不用抗生素,为生产"无菌、无抗"安全鸡蛋提供技术支撑。 相似文献
108.
Influences of sand cover on erosion processes of loess slopes based on rainfall simulation experiments 总被引:1,自引:0,他引:1
Aeolian-fluvial interplay erosion regions are subject to intense soil erosion and are of particular concern in loess areas of northwestern China.Understanding the composition,distribution,and transport processes of eroded sediments in these regions is of considerable scientific significance for controlling soil erosion.In this study,based on laboratory rainfall simulation experiments,we analyzed rainfall-induced erosion processes on sand-covered loess slopes(SS)with different sand cover patterns(including length and thickness)and uncovered loess slopes(LS)to investigate the influences of sand cover on erosion processes of loess slopes in case regions of aeolian-fluvial erosion.The grain-size curves of eroded sediments were fitted using the Weibull function.Compositions of eroded sediments under different sand cover patterns and rainfall intensities were analyzed to explore sediment transport modes of SS.The influences of sand cover amount and pattern on erosion processes of loess slopes were also discussed.The results show that sand cover on loess slopes influences the proportion of loess erosion and that the compositions of eroded sediments vary between SS and LS.Sand cover on loess slopes transforms silt erosion into sand erosion by reducing splash erosion and changing the rainfall-induced erosion processes.The percentage of eroded sand from SS in the early stage of runoff and sediment generation is always higher than that in the late stage.Sand cover on loess slopes aggravates loess erosion,not only by adding sand as additional eroded sediments but also by increasing the amount of eroded loess,compared with the loess slopes without sand cover.The influence of sand cover pattern on runoff yield and the amount of eroded sediments is larger than that of sand cover amount.Furthermore,given the same sand cover pattern,a thicker sand cover could increase sand erosion while a thinner sand cover could aggravate loess erosion.This difference explains the existence of intense erosion on slopes that are thinly covered with sand in regions where aeolian erosion and fluvial erosion interact. 相似文献
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Xiao-feng YUE Yan-lun JU Zi-zhu TANG Ya-meng ZHAO Xu-liang JIAO Zhen-wen ZHANG 《农业科学学报》2019,18(9):2052-2062
The effects of the severity and timing of leaf removal(LR) on the amino acids of Sauvignon Blanc grapes and wines were studied during the 2017 growing season. High-performance liquid chromatography(HPLC) was used to analyze the amino acids profiles of grape berries and wines. The basal leaves were removed at three time points(40, 56 and 72 days after flowering, named LR40, LR56 and LR72, respectively) at two severity levels(one at which the first, third, and fifth basal leaves of each shoot were removed(50% level); and another at which the first six basal leaves were removed(100% level)). The results showed that leaf removal had little impact on total soluble solids(°Brix), titratable acidity, pH or berry weight. The LR72-50% treated grapes had higher berry weight, titratable acidity and °Brix than those of the other treatments. The highest concentrations of total amino acids and of total amino acids except proline were detected in LR72-50% treated grapes(2 952.58 and 2 764.36 mg L~(-1), respectively); the lowest were detected in LR72-100% treated grapes(2 172.82 and 2 038.71 mg L~(-1), respectively). LR72-50% treatment significantly promoted the synthesis of aspartic acid, serine, arginine, alanine, aminobutyric acid and proline at both severity levels for grapes, the concentrations of all of these amino acids were increased relative to the control concentrations. The LR72-50%, LR40-100% and LR72-100% treated wines had higher total amino acids concentrations and higher concentrations of some individual amino acids, such as arginine, alanine and serine, than did the control wines. Of all the amino acids studied, glycine, tyrosine, cysteine, methionine and lysine were not significantly influenced by the timing or severity basal defoliation in grapes and wines. The present study reveals the effects of the timing and severity of leaf removal on the amino acids profiles of grapes and wines. 相似文献