XIII. Yeast sequencing reports. Cloning and sequencing of the NES24 gene of Saccharomyces cerevisiae

We have cloned NES24 using a temperature-sensitive nes24-1 mutant as a host and sequenced a 3162 bp XhoI-EcoRI DNA fragment containing the NES24 gene. Computer analysis revealed that this segment contains a 1806 bp open reading frame which is needed for complementation of the nes24-1 mutation. We found SUP8 in the region upstream of the NES24 gene, placing the NES24 gene on chromosome XIII. A protein homology search indicated that NES24 encodes a new protein. The disruption of the NES24 gene resulted in temperature-sensitive growth. The sequence has been deposited in DDBJ/EmBL/GenBank data bases under Accession Number D15052.     

新霉素酶联免疫检测方法的研究——新霉素抗体的制备

以碳化二亚胺作为偶联剂,分别将新霉素(Neomycin,NEO)和牛血清白蛋白(Bovine serum albu-min,BSA)、血蓝蛋白(Keyhole limpet hemocyanin,KLH)进行偶联,得到偶联产物BSA-NEO和KLH-NEO。对BSA、KLH、NEO及其偶联产物BSA-NEO、KLH-NEO进行红外光谱分析,结果显示偶联产物的红外光谱中同时存在载体蛋白和NEO的特征吸收峰,初步证明偶联成功;将偶联产物BSA-NEO和KLH-NEO作为新霉素免疫抗原,分别免疫新西兰大白兔,成功获取新霉素抗血清,间接ELISA法测得抗血清效价可达1.28×105以上。     

Elaboration of neosamine rings in the biosynthesis of neomycin and butirosin

The proteins Neo-11 and Neo-18 encoded in the neomycin gene cluster (neo) of Streptomyces fradiae NCIMB 8233 have been characterized as glucosaminyl-6'-oxidase and 6'-oxoglucosaminyl:L-glutamate aminotransferase, respectively. The joint activity of Neo-11 and Neo-18 is responsible for the conversion of paromamine to neamine in the biosynthetic pathway of neomycin through a mechanism of FAD-dependent dehydrogenation followed by a pyridoxal-5'-phosphate-mediated transamination. Neo-18 is also shown to catalyze deamination at C-6' of neomycin, thus suggesting bifunctional roles of the two enzymes in the formation of both neosamine rings of neomycin. The product of the btrB gene, a homologue of neo-18 in the butirosin biosynthetic gene cluster (btr) in Bacillus circulans, exhibits the same activity as Neo-18; this indicates that there is a similar reaction sequence in both butirosin and neomycin biosynthesis.     

Palygorskite sheets prepared via tape casting for wound healing applications

The main objective was to increase the applicability of palygorskite by palygorskite sheets using a tape casting method. The stability of the suspension was investigated and the tapes were characterized by TGA/DTA, XRD, and SEM-FEG. The antimicrobial activity was analyzed in order to test the applicability of a newly modified drug release system that incorporates neomycin in palygorskite. Preliminary results showed that the palygorskite sheet prepared via the tape casting is promising for wound healing applications.     

新霉素的直接竞争酶联免疫分析法

首先用碳二亚胺(EDC)法将新霉素(NEO)偶联于载体蛋白-卵清白蛋白(ovalbumin,OVA),合成包被原OVA-NEO,SDS-PAGE 进行鉴定;用高碘酸钠法连接辣根过氧化物酶(horseradish peroxidase,HRP),制备酶标抗原NEO-HRP并建立直接ELISA检测方法。通过一系列参数的优化,包括包被溶液、封闭溶液、竞争时间、抗体稀释液、pH值、反应温度、显色时间等,最终得到其IC20(抑制率为20%时的标准溶液质量浓度)＜1ng/mL、半数抑制量(IC50)为7.6ng/mL,线性方程为y =－0.2798x＋0.7456,R2=0.991。直接ELISA总耗时只需大约1h。     

保加利亚乳杆菌H+-ATPase弱化菌株的诱变选育

以保加利亚乳杆菌ND06(Lactobacillus delbrueckii subsp.bulgaricus ND06)为出发菌株,利用硫酸新霉素诱变、筛选出一株H+-ArPase 弱化菌株ND06-6.该菌株在MRS培养基中,37℃培养18 h时,H+-ATPase活性为0.65 μmol/(mg· min),和出发菌株相比,H+-ATPase活性下降了35％.在脱脂乳培养基中培养0,4,8,12,16,20,24,36,48和72 h后,诱变菌株ND06-6的乳酸、乳糖和半乳糖的的代谢能力明显低于出发菌株.这些研究结果为弱后酸化酸奶发酵剂的开发和应用提供了理论依据.     

新霉素半定量胶体金试纸条的研制

建立了一种快速、简单的检测牛乳中新霉素残留量的胶体金免疫层析法。将不同浓度的新霉素人工合成完 全抗原包被在硝酸纤维素膜上作为检测线（T1、T2线）,与待测牛乳样品中的新霉素竞争结合新霉素单克隆抗体- 胶体金标记物,通过两条T1、T2线显色情况使传统新霉素胶体金试纸条由定性检测准确到半定量检测。试纸条对 牛乳样品的半定量检测限分别为200 μg/kg和400 μg/kg,该检测限满足欧盟及国家对新霉素检测的需求,且检测牛 乳样品能够满足现场快速检测的要求,为现场快速检测牛乳中新霉素残留提供了更精确的参考依据。     

超高效液相色谱-串联质谱法测定鲟鱼中庆大霉素和新霉素残留量

目的建立超高效液相色谱-串联质谱法(ultra performance liquid chromatography-tandemmass spectrometric,UPLC-MS/MS)检测鲟鱼中庆大霉素和新霉素的分析方法。方法样品经10mmol/L磷酸盐缓冲溶液提取, 0.1%甲酸沉淀蛋白, HLB固相萃取柱净化。采用CORTECS HILIC(100 mm×2.1 mm, 1.6μm)色谱柱分离,以0.1%甲酸溶液(A)和乙腈(B)作为流动相进行梯度洗脱,通过电喷雾正离子扫描(electronic spray ion,ESI+),多反应监测模式(multiplereaction monitoring,MRM)对庆大霉素和新霉素的定量离子和定性离子进行测定。结果本方法在5 min内完成2种目标化合物的分离分析。庆大霉素在25～300μg/L浓度范围内呈现良好的线性关系,相关系数r20.995;方法检出限为10μg/kg,定量限为25μg/kg;添加量为25、50、100μg/kg时回收率在76.7%～106.3%之间,相对标准偏差(relative standard deviation, RSD)在0.18%～2.15%之间(n=6)。新霉素在50～600μg/L浓度范围内呈现良好的线性关系,相关系数r20.996;方法检出限为20μg/kg,定量限为50μg/kg;在50、100、200μg/kg添加水平的回收率为96.1%～109.0%之间,相对标准偏差(RSD)在0.72%～2.84%之间(n=6)。结论该方法精密度好、灵敏度高,能简便、准确地测定鲟鱼中庆大霉素和新霉素的药物残留。     

Validation of two enzyme immunoassays for aminoglycoside residues according to European Decision 657/2002

Aminoglycoside antibiotics are commonly used to treat bacterial infections in human and veterinary practice. Owing to their toxicity, the European Community has established maximum residue limits (MRL) in foodstuffs of animal origin (EEC No 2377/90). In the present study, the performance of two new enzyme immunoassays (EIA), I'screen Gentamicin and I'screen Neomycin, for the quantitative detection of the aminoglycosides, gentamicin and neomycin, in milk and tissue are described. Validation of these EIAs has been performed in accordance to the criteria of European Decision 657/2002. Assays sensitivity at the MRLs was 95% for milk samples and 100% for tissue samples, while specificity was 100% at 33 and 25% of the MRLs for milk and tissues, respectively. The performance of these EIAs indicates that they can be used as easy screening methods for the analysis of aminoglycosides in milk and tissue samples.