兰州大尾羊心脏型脂肪酸结合蛋白（H-FABP） 基因克隆及其同源性比较

【目的】克隆兰州大尾羊心脏型肪酸结合蛋白（H-FABP）基因全长cDNA序列,为研究绵羊H-FABP生物学作用和生产应用提供理论依据。【方法】根据已知哺乳动物H-FABP基因 cDNA 序列,设计5''和3''特异引物,运用cDNA 末端快速扩增（RACE）技术获得兰州大尾羊H-FABP基因全长 cDNA 序列。【结果】 扩增获得兰州大尾羊5''端425 bp、3''端231 bp片段和 177 bp中间片段,拼接获得748 bp兰州大尾羊H-FABP基因全长cDNA 序列（GenBank登录号：JQ780322）。 兰州大尾羊H-FABP基因ORF长 402 bp,编码 133 个氨基酸。核苷酸序列分析显示兰州大尾羊H-FABP基因序列与大多数哺乳动物相似,但其第66位发生的碱基转换（T←→G）引起所编码的第22位天门冬氨酸（N）不同于其它所有物种的赖氨酸（K）。构建的基因进化树分析结果显示兰州大尾羊与山羊亲缘关系最近。预测兰州大尾羊H-FABP蛋白质的空间结构与山羊和牛H-FABP类似,由2个α螺旋和10个反向平行的β折叠组成,10 个折叠片围成一个桶状结构,疏水性残基位于桶内,用于结合脂肪酸。【结论】克隆了兰州大尾羊H-FABP基因,为进一步研究该基因的功能奠定了基础。     

Monitoring chemical changes of dry-cured Parma ham during processing by surface autofluorescence spectroscopy

Parma hams at various processing stages were investigated by surface autofluorescence spectroscopy. Fluorescence "landscapes" of raw meat and salted (3 months), matured (11 and 12 months), and aged (15 and 18 months) Parma hams were obtained, and a three-dimensional data array (sample x emission x excitation) was used to develop a PARAFAC model including five components, which all exhibited characteristics of pure fluorophores regarding both excitation and emission spectra. The relative amount of each component related strongly to the processing stage, and sample age showed good correlation to fluorescence data (R = 0.98), with a relative error of prediction of approximately 1 month. Fluorescence measurements from samples of either semimembranosus or biceps femoris were used to predict chemical or sensory reference data, yielding good correlation for biceps femoris data, thereby enabling moisture content, sensory and instrumental color, and proteolysis value to be fairly well predicted. Overall, surface autofluorescence of Parma hams proved to hold relevant information, relating to major chemical/physical changes during processing. It is concluded that fluorescence spectroscopy has potential as an innovative method of quality control in dry-cured ham.     

浙江天童国家森林公园常绿阔叶林主要组成树种材积与生物量相关关系探讨

以天童国家森林公园常绿阔叶林主要组成树种为研究对象,通过测定其各组分生物量,建立了实测生物量与材积之间的回归模型,结果表明:主要组成树种各组分生物量与其材积之间存在着密切的相关关系,各主要树种材积与生物量的回归模型存在差异;回归方程精度较高,用于根据地区常绿阔叶林主要树种材积推算其生物量是可行的。     

20世纪60年代以来黄土高原小流域泥沙来源的方法与历史侵蚀过程研究进展

小流域作为黄土高原水土流失综合治理的基本单元,赋存了大量的泥沙侵蚀特征和侵蚀环境变化信息。它在减少黄土高原土壤侵蚀方面发挥着十分重要作用。概述了20世纪60年代以来黄土高原小流域泥沙来源和历史侵蚀过程方面的研究进展,小流域泥沙来源主要从传统方法、元素示踪法及REE稀土元素示踪法方面进行了分析,展望了未来小流域泥沙来源及泥沙侵蚀研究的发展,为小流域开展水土保持工作、对水土资源进行科学的评价和开展更深入的研究提供了重要参考。     

Herd prevalence of Salmonella enterica infections in Danish slaughter pigs determined by microbiological testing

As a part of a nationwide programme to survey and control salmonella in pig herds, a microbiological survey of 1363 pig herds was performed in Denmark. A total of 13 468 slaughter pigs were examined at slaughter by culture of 5 g of caecal contents. Overall, 30 different serotypes of Salmonella enterica were isolated from 832 pigs (6.2%). The predominant serotype was S. Typhimurium, comprising 536 (64.4%) of the isolates. Four hundred and forty-eight isolates of S. Typhimurium were examined by phage typing, resulting in detection of 17 different phage types (definitive types, DT) with DT12 being the most frequent (49.1%).

Salmonella enterica was found in 302 herds (22.2%), S. Typhimurium was found in 61.1% of these. 279 (23.1%) large herds (producing more than 2600 slaughter pigs per year) were found to be salmonella positive compared with 23 (14.7 %) small herds (annual production of 500 to 550 slaughter pigs). Practical constraints in the study design did not allow for a firm conclusion on the interplay among herd size, geographical location and occurrence of salmonella.

In 284 of 302 infected herds (94.0%) only one serotype was detected. Infections with two different serovars were seen in 18 herds (6.0%).     

Evidence of long distance airborne transmission of Aujeszky's disease (pseudorabies) virus

Aujeszky's disease has been the subject of an eradication campaign in Denmark since 1980. A detailed knowledge of the virus strains present in the country was provided by restriction fragment analyses of older clinical isolates, and of isolates from all the virologically confirmed outbreaks since 1985. The introduction of foreign strains into southern border areas was demonstrated during the winters of 1984/85, 1986/87 and 1987/88. An epizootic during the winter of 1987/88 was shown to correlate with an unusual predominance of southerly winds. Both conventional and specific pathogen free herds became infected. A herd level case-control analysis of the outbreaks during the winter of 1987/88 revealed that there was a positive correlation between the risk of infection and the size of the herd. The observations support the hypothesis of airborne transmission of the disease.     

牛GDF-9基因的克隆与组织表达的分析

为了检测牛GDF-9基因mRNA在怀孕期牛生殖系统的表达情况,为GDF-9基因在雌性动物繁殖上的研究提供一定的理论依据。本试验根据GenBank中报道的牛GDF-9基因序列设计引物,从牛卵巢、输卵管、子宫、肾脏中提取RNA,采用RT-PCR技术进行cDNA扩增,扩增产物与载体pGM-T连接,转化大肠杆菌DH5α,筛选阳性克隆,测序。结果表明,已成功克隆的阳性重组子经测序鉴定其片段大小与预期大小完全一致,为264 bp。序列同源性分析比较表明,该cDNA及其推导的氨基酸序列与绵羊GDF-9cDNA和氨基酸序列同源性分别为97%和94%。以-βactin为内参照物,采用RT-PCR技术进行半定量分析,通过检测比较牛GDF-9基因在卵巢、输卵管、子宫、肾脏组织中mRNA的表达情况。结果表明,牛GDF-9基因在卵巢中表达量最高,在输卵管、子宫、肾脏中均有表达,但表达量不高。     

Changes in volatile compounds of carrots (Daucus carota L.) during refrigerated and frozen storage

Carrots (Daucus carota L.) of cv. Bolero and cv. Carlo were processed into shreds and stored for up to 4 months at -24 degrees C (frozen storage), or the roots were stored for up to 4 months at 1 degrees C (refrigerated storage) followed by processing into shreds. Volatiles from the carrot shreds were collected by dynamic headspace technique and analyzed by GC-FID, GC-MS, GC-MS/MS, and GC-O to determine the volatile composition and aroma active components of carrots stored under different temperature conditions. A total of 52 compounds were quantified, of which mono- and sesquiterpenes accounted for approximately 99% of the total volatile mass. Major volatile compounds were (-)-alpha-pinene, beta-myrcene, (-)-limonene, (+)-limonene, (+)-sabinene, gamma-terpinene, p-cymene, terpinolene, beta-caryophyllene, alpha-humulene, and (E)- and (Z)-gamma-bisabolene. A considerable increase in the concentration of mono- and sesquiterpenes was observed during refrigerated storage, whereas the concentration of terpenoids was around the same level during frozen storage. GC-O revealed that the major volatiles together with (+)-alpha-pinene, (-)-beta-pinene, (+)-beta-pinene, 6-methyl-5-hepten-2-one, (-)-beta-bisabolene, beta-ionone, and myristicin had an odor sensation, which included notes of "carrot top", "terpene-like", "green", "earthy", "fruity", "citrus-like", "spicy", "woody", and "sweet".