无菌压缩空气在保鲜奶加工中的应用

本文介绍了无菌压缩空气在保鲜奶生产中的应用，并介绍了一套完整的无菌空气处理系统。     

Material in the middle ear of dogs having magnetic resonance imaging for investigation of neurologic signs

The aim of this study was to determine the prevalence and potential significance of finding material in the middle ear of dogs having magnetic resonance (MR) imaging. Of 466 MR studies reviewed, an increased signal was identified in the tympanic bulla in 32 (7%) dogs. Cavalier King Charles spaniels, Cocker spaniels, Bulldogs, and Boxers were over-represented compared to the population of dogs having MR imaging. Five (16%) dogs had definite otitis media and one (3%) had a meningioma invading the middle ear. Of the remaining dogs, 13 (41%) had possible otitis media and 13 (41%) had neurologic conditions apparently unrelated to otitis media. The most common appearance of material in the middle ear was isointense in T1-weighted images and hyperintense in T2-weighted images. There was no apparent correlation between the signal characteristics of the material and the diagnosis. Enhanced signal after gadolinium administration was observed affecting the lining of the bulla in dogs with otitis media and in dogs with unrelated neurologic conditions. In dogs without clinical signs of otitis media, finding an increased signal in the middle ear during MR imaging may reflect subclinical otitis media or fluid accumulation unrelated to inflammation. Brachycephalic dogs may be predisposed to this condition.     

Adherence of Actinobacillus pleuropneumoniae serotype 1 to swine buccal epithelial cells involves fibronectin

The swine pathogen Actinobacillus pleuropneumoniae serotype 1 was investigated for its ability to adhere to swine, rat, and human buccal epithelial cells (BEC). The highest number of bacteria adhered was to swine BEC. This binding ability was affected by heating, extreme pH, treatment with sodium dodecyl sulfate, ethylenediamine tetraacetate, or periodate, and proteolysis, suggesting that cell-surface glycoproteins participate in adherence and that adherence is based mostly on ionic interactions. Mannose and swine fibronectin may play a direct role in this interaction. Convalescent-phase serum from naturally infected pigs inhibited the adhesion. There was a correlation between bacterial pathogenicity as well as host specificity and the capacity for adherence to swine BEC. Adhesion to swine BEC provides a convenient method to study in vitro the adherence of A. pleuropneumoniae and other pathogens of the pig respiratory tract.     

Identification and Characterisation of Bacteria Causing Soft-rot in Agave tequilana

Agave tequilana is the raw material for the production of the alcoholic beverage tequila. A bacterial disease has affected the A. tequilana crop in recent years. Previous reports based on colony and cell morphology, Gram stain and potato rot indicated that Erwinia sp. is the main pathogen. We isolated a several bacterial isolates capable of producing soft-rot symptoms in greenhouse pathogenicity assays. An extensive characterisation involving pathogenicity tests, fatty acid profile, metabolic and physiological properties, ribosomal DNA sequence and intergenic transcribed spacer amplification (ITS-PCR) and restriction banding pattern (ITS-RFLP) was made of each isolate. Three different species: Erwinia cacticida, Pantoea agglomerans and Pseudomonas sp. were identified. Fatty acid and metabolic profiles gave low similarity values of identification but 16S rDNA sequence, ITS-PCR and ITS-RFLP confirmed the identification of E. cacticida. In the phylogenetic tree, E. cacticida from blue agave was grouped neither with E. cacticida type strains nor with Erwinia carotovora. This is the first report that associates E. cacticida with A. tequilana soft-rot symptoms.     

Evaluation of Olive Cultivars for Resistance to Verticillium dahliae

Resistance of 23 important olive cultivars to Verticillium dahliae has been evaluated in four experiments under controlled conditions. Nine-month-old nursery olive plants were inoculated with a cotton non-defoliating (ND) (V4) or a cotton defoliating (D) (V117) isolate of V. dahliae. Resistance was evaluated by assessing symptom severity using a 0–4 rating scale and estimating the area under disease progress curves. The percentage of plants killed and of those which recovered from the disease were used as additional parameters for including a particular cultivar into a defined category. Most of the evaluated cultivars were susceptible, although at different levels, to both isolates of V. dahliae. All cultivars were more susceptible to the D pathotype than to the ND one. A group of 11 cultivars, including several important Spanish cultivars, were susceptible or extremely susceptible to both pathotypes of V. dahliae. A second group showed differences of resistance depending on the pathotype used. They were susceptible or extremely susceptible to the D pathotype but resistant or moderately susceptible to the ND one. Finally, 'Frantoio', 'Oblonga' and 'Empeltre' were moderately susceptible to the D isolate of V. dahliae and resistant to the ND one. The resistance of 'Empeltre' was evident by the plant ability to recover from infection with either isolates. 'Empeltre' is considered to be a valuable cultivar for inclusion in breeding programmes for resistance to Verticillium wilt.     

蚕粪中提取叶绿素铜钠盐的稳定性研究

以蚕粪为原料,95%的乙醇为溶剂提取叶绿素,并通过化学法制得叶绿素的铜纳盐。采用721分光光度计对叶绿素铜钠盐进行定性、定量测定,确定该色素测定系统中的最大波长为414nm。通过测量吸光值研究了几种常用食品添加剂对叶绿素铜钠盐稳定性的影响,并对其耐光、耐热、耐酸碱及耐氧化性、耐还原性进行探讨。结果表明:叶绿素铜钠盐在70℃以下稳定性较好;光照对叶绿素铜钠盐稳定性的影响较大;还原剂(Na2S2O3)对叶绿素铜钠盐稳定性的影响较大,氧化剂在短时间内对其稳定性的影响不大,但放置的时间不宜超过30min;叶绿素铜钠盐在pH值为6以上的溶液中较为稳定,且有机酸及单糖对其稳定性无明显影响。     

植物育种的物理学方法

介绍了草原生态恢复中选育优良牧草种子的一些物理学方法,包括电场、磁场、物理辐射、激光、离子束和交变应力等在植物的生物学效应、诱变育种和转基因技术中的应用.     

大豆多肽的性质及其研究进展

大豆多肽(Soy peptide)是大豆蛋白质经酶解作用后的多肽分子混合物。与大豆蛋白相比,大豆肽具有更好的理化性质,含有多种生理活性物质,在机体内具有更多种生理功能,近年来引起人们的广泛关注。     

日粮中添加杜仲提取物对肉仔鸡生产性能的影响

选用825只艾维茵肉仔鸡,随机分为5组,每组5个重复,每个重复33只鸡。对照组饲喂基础日粮,试验组在基础日粮中分别添加1500,2000,2500g/t的杜仲提取物或50mg/kg的效美素,比较杜仲提取物对肉仔鸡生产性能及胴体品质的影响。试验分2个阶段(0～21d和21～42d),试验鸡自由采食和饮水。研究结果表明,1)日粮中添加杜仲提取物能降低采食量,提高肉仔鸡成活率,其中以添加1500g/t杜仲提取物效果较好。2)杜仲提取物能促进肌肉组织蛋白质的合成,降低体内脂肪的沉积,在一定程度上改善肉仔鸡胴体品质。     

利用血液蛋白及酶多态性分析技术鉴定山羊亲缘关系的研究

选择血红蛋白(Hb)、运铁蛋白(Tf)、亮氨酸胺肽酶(LAP)、前白蛋白3(Pa3)、淀粉酶(Amy)对可能为同卵双生波尔山羊的亲缘关系鉴定。结果发现，除淀粉酶(Amy)和亮氨酸胺肽酶(Lap)外，其余位点均有多态性。由蛋白位点的基因型判定羔1、羔2基因型完全一致，是供体后代的概率为75G，受体后代的概率为22．8％，从而确认羔1、羔2的双亲为供体公羊和供体母羊。