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31.
Simon R. M. Jones Benjamin Goh Gina Prosperi-Porta 《Aquaculture (Amsterdam, Netherlands)》2003,220(1-4):157-164
The effect of fixative and duration of fixation on the sensitivity of a non-radioactive in situ hybridisation (ISH) protocol to detect Kudoa thyrsites small subunit ribosomal deoxyribonucleic acid (DNA) was investigated. Strong ISH reactions were detected in 5-μm sections of paraffin-embedded Atlantic salmon muscle after fixation for 1 day in Davidson's solution (DS). Reactions were weak following 3 or 5 days fixation and absent after 17 or 28 days fixation. Strong ISH reactions were observed after 1, 3 or 5 days fixation in neutral buffered formalin (NBF). The reactions were weak after 17 days and weak to nonexistent after 28 days of fixation. Reactions were consistently strong after fixation in 95% ethanol for up to 28 days. Some mature spores reacted weakly or not at all by ISH. Parasite DNA was weakly amplified by polymerase chain reaction (PCR) from paraffin-embedded muscle after 1 day of fixation in DS but not after fixation for 3, 5, 17 or 28 days. Amplified DNA was detected after fixation in NBF for 1, 3 and 5 days, but not after 17 or 28 days. In contrast, PCR consistently amplified DNA from paraffin-embedded, ethanol-fixed muscle. Caution should be used in the choice of fixative and duration of fixation when preserving Atlantic salmon tissues for molecular diagnosis of K. thyrsites. 相似文献
32.
循环农业经济的发展需要从整个循环系统和整个管理过程来理解,该研究将消费者纳入循环农业行为主体,基于利益相关者理论,分析了实施绿色供应链管理的影响因素包含认知、制度、资金、技术等方面17个要素;在前人研究的基础上,通过对影响因素之间的关系进行推理和计算,得到了影响因素体系的ISM模型.该模型为7级递阶结构模型,包含直接因素、间接因素和深层因素3个层次.直接因素主要和农业企业有关,间接因素关系到中介组织、农户和消费者3个行为主体,深层原因则来源于政府行为.通过AHP法的求解,确定了中介组织在其与消费者、农产三者关系中的重要性. 相似文献
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从臭蜣螂中提取甲壳素/壳聚糖的研究 总被引:9,自引:0,他引:9
甲壳素作为自然界中产量仅次于纤维素的第二大生物资源 ,近年来其开发和应用日益受到重视 ,但目前甲壳素的生产原料来源有限 ,生产成本较高。而昆虫是世界上最大的优势动物种类 ,昆虫的总生物量超过了地球上所有动物总生物量 ;但被人类利用的昆虫资源却很少。昆虫是当今地球上未被利用的最大生物资源 ,特别是昆虫的甲壳素资源尚未开发。鉴于目前对于昆虫甲壳素资源的开发尚在尝试阶段 ,本文以臭蜣螂为材料 ,进行了提取甲壳素和壳聚糖的工艺以及其理化特性研究。研究发现 ,臭蜣螂体中甲壳素含量高出目前甲壳素生产常规原料虾蟹壳数倍 ,且从其体中提取的甲壳素与壳聚糖的品质在残留灰分、粘度和色泽等方面优于虾蟹壳。并以单因素试验方法进行了提取甲壳素和壳聚糖提取工艺的研究 ,提出了从臭蜣螂中提取甲壳素和壳聚糖的提取工艺 :①脱矿物质 :用 0 8mol·L- 1 HCl预先 70℃加热 30min ,然后室温条件下浸泡 12h ;②脱蛋白质、脂类 :用 2 0~ 2 5mol·L- 1 NaOH ,在 90~ 10 0℃条件下 ,处理 4~ 5h ;③脱乙酰基 :用 10 0 0~ 11 2 5mol·L- 1 NaOH ,在 130℃条件下 ,处理 3h。 相似文献
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Summary Ninety Chinese rice landraces were examined with special reference to the indica-japonica differentiation in terms of traditional criteria, isozyme analysis and PCR analysis of the chloroplast DNA (cpDNA). Cultivars were separated into indica and japonica defined by a discriminant function (Z) based on key characters, as well as by isozyme genotypes. Most indica landraces had chloroplast DNAs with a deletion at the Pst-12 fragment, while most japonica landraces had cpDNAs without the deletion. Two traditionally recognized varietal groups in China, keng and hsien, corresponded largely to the respective japonica and indica revealed in our study. The results obtained in this study showed good agreement for classification of indica and japonica types by the three methods: discriminant analysis by Z value, isozyme analysis, and PCR analysis for cpDNA. 相似文献
38.
Rotfinder is a non-destructive decay-sensing apparatus based on resistance measurements in standing trees. The accuracy of Rotfinder in detecting decay was evaluated in 500 standing trees in three Norway spruce (Picea abies) plots. Trees were measured at three heights, 0.30, 0.66 and 1.30 m. Sections were later inspected for the presence of decay and reaction zones. Inspected trees were mostly infected by Heterobasidion annosum and showed a large variation in the amount of decay present, ranging from 0.1% to 88.0% of the section. Correctly and incorrectly classified trees were compared in terms of ion and element concentration, density and moisture. Measurements at stump level (0.30 m) were more accurate than measurements at breast height (1.30 m) where the reaction zone and decay columns showed lower moisture content. The accuracy of Rotfinder increased when trees with small decay columns were regarded as ‘non-decayed’. When only trees with more than 15% of the section decayed were regarded as ‘decayed’, Rotfinder had an accuracy of 0.86 when performing assessments at stump level. False negatives, as opposed to true positives, corresponded to trees with smaller and drier decay columns, drier reaction zones and lower K+ (potassium) concentration in the decay column. False positives corresponded to trees with large sapwood and high sodium content in the sapwood. Rotfinder represents an alternative to the standard method of using increment core observations to assess decay in living trees. 相似文献
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保存二年以上的过二硫酸铵固体试剂,因逐渐分解而使溶液酸度过低,无法定量测出过二硫酸铵与碘化钾反应级数,改变各反应物量并加入适量氟化氢铵,可使反应顺利进行. 相似文献
40.
浅析农业产业链管理与提高农业综合生产力 总被引:1,自引:0,他引:1
通过提高农业综合生产力来增加农民收入是解决“三农”问题的一条途径,农业产业链管理可以有效地提高农业综合生产力。通过对农业产业链管理理论的回顾,结合我国农业现状,提出我国农业产业链管理的具体内容以及完善农业产业链管理的具体措施。 相似文献