QuEChERS净化—超高效液相色谱—串联质谱法同步测定荔枝中10种植物生长调节剂残留

[目的]建立同步测定荔枝中甲哌啶、矮壮素等10种植物生长调节剂(PGRs)残留的QuEChERS净化—超高效液相色谱—串联质谱法(UPLC-MS/MS),为荔枝中多种PGRs残留同步检测提供技术参考.[方法]荔枝样品以1%(v/v)乙酸—乙腈提取,经优化QuEChERS前处理后,净化后的样品提取液以Agilent InfinityLab Poroshell 120 EC-C18柱为分离色谱柱,甲醇—5 mmol/L乙酸铵水溶液(含0.1%甲酸,v/v)缓冲溶液为流动相梯度洗脱,以UPLC-MS/MS在选择反应监测模式下对甲哌啶等10种PGRs目标物残留进行测定.[结果]在5~100μg/kg范围内,10种PGRs质量浓度与对应的峰面积呈良好线性,相关系数(r2)均>0.9950;检出限范围为0.03~0.60μg/kg.在10、25和100μg/kg 3个添加水平范围内,平均回收率在71.8%~109.2%,相对标准偏差(RSD)在0.6%~10.0%.用优化的QuEChERS净化-UPLC-MS/MS对40份荔枝样品进行检测,其中1份样品检出多效唑,1份样品检出芸苔素内酯,PGRs检出率为5.0%.[结论]建立的QuEChERS净化-UPLC-MS/MS简便、快速,具有良好的灵敏度、准确度和精密度,可用于同步测定甲哌啶等10种PGR在荔枝中的残留.     

广西城乡居民收入差距与经济增长关系的实证研究

选用城镇居民人均可支配收入、农村居民人均纯收入和环比经济增长率3项指标,根据1980～2009年统计年鉴中的时序数据,运用ADF检验、Granger因果关系检验等方法对广西城乡居民收入与经济增长的关系进行分析。结果表明,库兹涅茨的经济增长与收入差距关系的理论不适于解释广西出现的城乡收入差距扩大的现象,＂滴流效应＂对缓解城乡收入的持续扩大也不会产生明显的效果。广西城乡居民收入差距扩大更多的是受到发展政策和城乡分割的经济体制制约而并非经济发展本身的影响。只有推进经济体制改革、打破城乡阻隔才是缩小城乡收入差距的最佳途径。     

虎斑乌贼受精卵卵黄营养成分分析

本实验对虎斑乌贼受精卵卵黄的营养成分进行分析,旨在探讨其幼体的营养需求量,为其幼体配合饲料研制提供参考数据。随机选取大约800个虎斑乌贼受精卵的卵黄,采用国家标准方法测定其水分、灰分、粗蛋白质、粗脂肪、氨基酸、脂肪酸和矿物元素含量。结果表明:1)虎斑乌贼受精卵卵黄中粗蛋白质含量为76.33%(干重基础);总氨基酸(TAA)和必需氨基酸(EAA)含量分别为71.22%和32.38%(干重基础),EAA/TAA为45.46%,氨基酸中以谷氨酸(Glu)含量最高(9.97%),必需氨基酸中亮氨酸(Leu)含量最高(7.58%)。2)其粗脂肪含量12.71%(干重基础);共检出17种脂肪酸,包括8种饱和脂肪酸(SFA)、5种单不饱和脂肪酸(MUFA)和4种多不饱和脂肪酸(PUFA),SFA、MUFA和PUFA分别占脂肪酸总量的43.47%、7.54%和49.25%,其中以DHA含量最高,达32.80%,EPA含量为7.70%,DHA/EPA为4.26。3)检测出Na、K、Ca、Mg、Sr、Mn、Fe、Cu、Zn、Al和As 矿物元素,微量元素中富含Zn、Al和Fe,含量分别为 0.77、0.71和0.43 mg/kg(鲜重基础)。由此可见,卵黄具有高蛋白、低脂肪,富含n-3PUFA的特点;虎斑乌贼幼体饲料中蛋白质需求量参考值为76.33%;氨基酸需求量参考值,如赖氨酸(Lys)为5.49%,蛋氨酸(Met)为2.63%;脂肪的需求量参考值为12.71%,DHA为4.17%,EPA为0.98%;微量元素需求量参考值,如Zn为2.77 mg/kg,Cu为0.19 mg/kg(干重基础)。     

斑马鱼端脑的微细形态与结构

为了深入了解斑马鱼端脑的微细形态和超微结构,采用光镜和电镜技术对斑马鱼端脑进行观察研究。斑马鱼端脑由左、右嗅球和左、右大脑半球构成。嗅球前方有一对嗅神经,后端伸出嗅茎与大脑半球联系。光镜下,嗅球组织结构从外向内依次为上皮层、神经纤维层、小细胞层和内部细胞层。大脑半球外部覆盖很薄的大脑皮,基部为纹状体,两者之间的腔隙为公共脑室。纹状体由神经核团和神经纤维构成。神经核团分布于纹状体周缘,主要有连前核、背嗅核、侧嗅核、视前核和脚内核等。神经纤维包括横行的前连合,纵行和斜行的中央嗅束和侧嗅束。电镜下,嗅球分层明显,可观察到僧帽细胞、神经胶质细胞和众多突触。大脑半球中可见神经胶质细胞、突触以及血脑屏障系统等。斑马鱼端脑形态结构与大多数硬骨鱼相似,但有个别核团存在差异。实验结果可为斑马鱼神经生物学模型的建立与应用提供有效的理论基础。     

The comparative pathogenicity of four serovars of Actinobacillus (Haemophilus) pleuropneumoniae

The pathogenicity of 2 isolates of each of serovars 7, 3, 1 and 2 of Actinobacillus pleuropneumoniae was tested by intranasal inoculation into 60, 6-week-old large white pigs. Four dose rates varying from 0.27 to 560 x 10(6) organisms per pig with 10-fold serial dilutions were used. Surviving pigs were necropsied 7 days after inoculation. The proportion of pigs dying and developing gross lesions following infection was significantly greater for pigs given serotype 1 than for each of the other 3 serotypes, which did not differ significantly from each other. Twelve of 16 pigs given either of the 2 isolates of serovar 1 died after acute illness and 1 of 44 pigs given either of the 2 isolates each of serovars 7, 3 and 2 died. Pigs given serovar 1 showed high temperatures, severe respiratory distress, frothy haemorrhagic nasal discharge and weight loss. Lung lesions were produced in all 16 pigs given serovar 1, in 7 of 14 pigs given serovar 7, 7 of 14 pigs receiving serovar 3 and in 5 of 16 pigs given serovar 2. The lethal infections were characterised by a severe acute fibrinohaemorrhagic necrotising pleuropneumonia, whereas non-lethal cases had lung lesions ranging from necrotising purulent pleuropneumonia to abscessation. Significant differences between isolates in proportions of tissues culture positive for A. pleuropneumoniae for serovars 7 and 2, but not for serovars 3 and 1 suggested that isolates may vary in virulence within serovars, but more detailed studies are needed to clarify this point.     

Why implantation of bio‐loggers may improve our understanding of how animals cope within their natural environment

Bio‐loggers are miniaturized autonomous devices that record quantitative data on the state of free‐ranging animals (e.g. behavior, position and physiology) and their natural environment. This is especially relevant for species where direct visual observation is difficult or impossible. Today, ongoing technical development allows the monitoring of numerous parameters in an increasing range of species over extended periods. However, the external attachment of devices might affect various aspects of animal performance (energetics, thermoregulation, foraging as well as social and reproductive behavior), which ultimately affect fitness. External attachment might also increase entanglement risk and the conspicuousness of animals, leaving them more vulnerable to predation. By contrast, implantation of devices can mitigate many of these undesirable effects and might be preferable, especially for long‐term studies, provided that the many challenges associated with surgical procedures can be mastered. Implantation may then allow us to gather data that would be impossible to obtain otherwise and thereby may provide new and ecologically relevant insights into the life of wild animals. Here, we: (i) discuss the pros and cons of attachment methods; (ii) highlight recent field studies that used implanted bio‐loggers to address eco‐physiological questions in a wide range of species; and (iii) discuss logger implantation in light of ethical considerations.