磷对水稻镉的亚细胞分布及化学形态的影响

为了探讨磷对水稻耐镉性的影响,采用盆栽实验,以沈农315(耐性)和花粳1417(敏感性)水稻为研究对象,对分蘖末期水稻根系及茎叶中镉的亚细胞分布以及化学形态进行比较分析。结果表明:增施磷肥显著降低了两品种水稻的镉含量,沈农315根系镉含量明显高于花粳1417,茎叶镉含量低于花粳1417;两品种各部位细胞壁镉的分配比例随磷的增加而明显增加,细胞器镉的分配比例逐渐降低。镉的化学结合形态整体上呈现为氯化钠提取态醋酸提取态去离子水提取态乙醇提取态盐酸提取态,其中醋酸提取态所占比例随磷增加而增加,沈农315和花粳1417的增幅分别为19.70%~31.32%、10.05%~16.36%,氯化钠提取态显著降低,降幅分别为23.38%~40.11%、22.55%~39.56%。由此说明,增施磷肥能有效增加水稻对镉的耐受性,且不同品种表现不同。     

南极磷虾拖网的性能优化分析

针对一顶中国目前正在使用的南极磷虾(Euphausia superba)拖网进行网具优化试验,设计了调整参数为浮沉比、上下手纲(等长)和叉纲的三因子L9(34)正交实验,并在3组L/S(水平扩张比)和5级拖速下完成了135次拖曳试验。结果表明:(1)随着拖速和L/S的增加,网具阻力增加,网口高度降低;(2)流速为3 kn情况下,L/S=0.45时,对阻力(Fs)和网具功率消耗(Ps)影响的主次顺序均为沉力(A)>叉纲(C)>手纲(B),对网口高度(Hs)影响的主次顺序为A>B>C,对能耗系数(Ce)影响的主次顺序为C>A>B,水动力性能的最优组合为A3B3C1;L/S=0.5时,对Fs、Hs和Ps影响的主次顺序均为C>A>B,对Ce影响的主次顺序为B>C>A,最优组合为A2B3C3;L/S=0.55时,对Fs和Ps影响的主次顺序均为C>A>B,对Hs影响的主次顺序为B>A>C,对Ce影响的主次顺序为B>C>A,最优组合为A2B3C3;(3)当L/S极低为0.2时,网口的水平扩张约为23 m,虽然此时网口高度有一定的提高,但网具的综合性能却显著下降,能耗系数增加;(4)增加沉力,适当放长手纲和叉纲可以有效提高已定型网具的性能。为确保在低拖速下达到网具的高扩张性能,应考虑改进网板性能,建议采用低拖速高扩张性网板。     

高效液相色谱法检测水产品中的孔雀石绿

采用高效液相色谱法检测水产品中的农药残留孔雀石绿。样品中的孔雀石绿经乙腈与乙酸铵提取,浓缩后固相萃取柱净化、硼氢化钾还原、反向色谱柱分离,再使用荧光检测器检测。应用该方法孔雀石绿的加标回收率在75.1%～95.1%之间,相对标准偏差3.7%～7.1%,检出限均为0.5μg/kg。结果表明:该方法检测孔雀石绿处理简单快捷,灵敏度高,可用于大量样品的快速分析。     

北京地区奶牛隐性乳房炎金黄色葡萄球菌的分离鉴定及药敏试验

为了解北京地区奶牛隐性乳房炎中金黄色葡萄球菌的感染情况及对常用药物的敏感性,用科玛嘉显色培养基和16SrRNA PCR检测方法对5个奶牛场的100份隐性乳房炎奶样进行金黄色葡萄球菌的分离鉴定,采用K-B纸片扩增法进行药敏试验。结果表明,显色培养基分离到24株疑似金黄色葡萄球菌,经16SrRNA PCR鉴定,15株为金黄色葡萄球菌;药敏试验结果显示,15株金黄色葡萄球菌均对β-内酰胺类中的氨苄西林产生普遍耐药性,对克林霉素和环丙沙星的耐药率较高,分别为53.33%和40%;对氧氟沙星、庆大霉素、头孢噻肟和头孢曲松的耐药性较低,耐药率为6.67%。说明15株金黄色葡萄球菌分离株对7类9种抗菌药物都有不同程度的耐药性。     

猪肉和鸡肉中脱氧雪腐镰刀菌烯醇和T-2毒素酶联免疫吸附检测方法的建立

为保障动物源性食品安全,本研究建立了分别检测猪肉和鸡肉中脱氧雪腐镰刀菌烯醇(deoxynivalenol,DON)和T-2毒素残留的间接竞争酶联免疫吸附法.结果显示,该方法在猪肉和鸡肉样本中DON的检测限分别为34.9和43.5 μg/kg,添加回收率为72.7%~97.1%,变异系数小于8.7%;T-2毒素的检测限分别为33.7和28.7 μg/kg,添加回收率为72.1%~95.0%,变异系数小于11.3%.该方法灵敏度高、准确、简便,适用于猪肉和鸡肉中DON和T-2毒素残留的快速检测.     

递增注射脂多糖诱导慢性免疫应激对仔猪生长性能的影响

本试验旨在研究递增30%注射脂多糖(LPS)诱导仔猪慢性免疫应激的效果及对仔猪生长性能、营养物质表观消化率的影响。选取16头断奶仔猪,随机分为2组(对照组、LPS组),单笼饲养。LPS组隔天静脉注射LPS,初始注射剂量80μg/kg BW,随后逐次递增30%,对照组注射相应剂量的生理盐水,试验期15 d。研究发现:仔猪注射LPS第1、5天血浆白细胞介素-1β和皮质醇含量极显著高于对照组(P0.01),第9天血浆皮质醇有高于对照组的趋势(P=0.10),整个试验期内血浆结合珠蛋白含量显著高于对照组(P0.05)。与对照组相比,注射LPS仔猪在试验的3个阶段(1~4 d、5~8 d和9~15 d)平均日增重分别降低了40.00%(P0.01)、29.52%(P0.05)和19.30%(P0.05),平均日采食量分别降低了25.09%(P=0.01)、23.15%(P0.05)和19.47%(P0.05),增重耗料比与对照组无显著差异(P0.05)。与对照组相比,注射LPS仔猪饲粮干物质表观消化率下降了5.43%(P0.05),能量表观消化率有降低的趋势(P=0.06),粗脂肪和粗蛋白质表观消化率略有降低(P0.10)。试验结果表明,递增30%注射LPS成功诱导仔猪慢性免疫应激,降低了仔猪平均日采食量和营养物质表观消化率,抑制了仔猪生长。     

竹鼠肠道中厌氧纤维素降解菌的分离与鉴定

本试验旨在从竹鼠肠道中分离厌氧纤维素降解菌并鉴定。取中华竹鼠盲肠内容物稀释,采用含2种不同纤维素[微晶纤维素(MCC)和羧甲基纤维素钠(CMC-Na)]的培养基在厌氧条件下对纤维素降解菌进行初筛,后又经以纤维二糖为唯一碳源的培养基的多次复筛,选出的菌株进行经形态学和分子生物学的鉴定。结果表明:经过初筛和复筛,筛选出了2株厌氧纤维素降解菌。初筛培养基采用MCC和CMC-Na最终筛选出的2株纤维素降解菌的纤维素酶活力分别为6.599和5.268U/m L。菌株经PCR鉴定、测序,用所得序列构建系统发育树,得出这2株菌与酪酸梭状芽孢杆菌(Clostridium butyricum)具有很高的同源性,达99%,二者均属于梭菌属(Clostridium)。本试验从竹鼠盲肠中成功筛选出2株纤维素降解菌,经鉴定确定属于梭菌属。     

Kinetics and postmucosal effects on urinary recovery of 5 intravenously administered sugars in healthy cats

The objective of this study was to describe the kinetics of urinary recovery and to evaluate the effects of postmucosal factors on urinary recovery of 5 intravenously administered saccharides. Ten cats received an isotonic sugar solution containing lactulose, rhamnose, xylose, methylglucose, and sucrose intravenously. These sugars were selected because of their prior use for intestinal permeability and mucosal function testing in humans and dogs. Urethral catheterization with a closed collection system was used for collection of cumulative urine samples prior to and 2, 4, 6, 8, 10, 12, and 24 h after administration of the sugar solution. High-pressure anion exchange liquid chromatography with pulsed amperometric detection was used to measure the concentrations of each sugar in the urine and calculate urinary recovery. Twenty-four hour cumulative urinary recovery for each sugar from the cats, was lower than expected compared to dogs and humans. All 5 sugars had the highest percentage of urinary recovery during the first 2 h after administration. Mean sugar elimination rate constants and half-lives ranged from 0.268/h for methylglucose to 0.415/h for lactulose and 1.67 h for lactulose to 2.59 h for methylglucose, respectively. Metabolism and incomplete urine collection are possible reasons for lower cumulative urinary recoveries of these 5 sugars in cats compared with dogs. Although these 5 sugars are not ideal marker molecules, they may still be useful for intestinal permeability and mucosal function testing in cats.     

Une nouvelle voie d'abord du ventricule latéral du cerveau chez la brebis (Ovis aries).

The proposed technique consists of placing a catheter in the olfactory recess of the lateral ventricle of the brain of a sheep. Twenty adult ewes were used in the study. The olfactory recess is in the frontal region 25 +/- 3 mm below the skin, just caudal to the line joining the supraorbital foramen and approximately 8-10 mm from the median plane. The approach is relatively easy under normal experimental conditions. The wall of the olfactory bulb, however, is fragile, and the animals must not have been injured by Oestrus ovis.