絮凝方法收集产氨短杆菌MA-2、黄色短杆菌MA-3条件的优化

采用壳聚糖作絮凝剂收集富含延胡索酸酶活力的产氨短杆菌MA-2、黄色短杆菌MA-3。研究了絮凝剂加入量及加入时混合方式与时间等因素对延胡索酸酶活力及分离效果的影响,并对壳聚糖絮凝收集产氨短杆菌MA-2、黄色短杆菌MA-3的过程进行了初步分析。     

产氨短杆菌与枯草杆菌发酵产肌苷比较试验

采用诱变得来的枯草杆菌GMI-741和产氨短杆菌GMA-2892在1.2L自控发酵罐上进行肌苷发酵试验,产氨短杆菌GMA-2802在种子培养基中培养15h后,菌浓度达1.0×1011个/ml,而同样条件下,枯草杆菌GMI-741菌浓度只有9.5×109个/ml.在1.2L自控发酵罐上发酵时,GMA-2802发酵周期54h,产肌苷达20.40g/L,发酵液主要原材料成本为441.1元/吨;GMI-741发酵周期60h,产肌苷达19.52g/L,发酵液主要原材料成本为559.1元/吨.     

螺旋藻过氧化氢酶的比较研究*

采用碘量法对毛乌素沙地碱湖的钝顶螺旋藻S1 与国外引进的钝顶螺旋藻S2 和极大螺旋藻S3 的过氧化氢酶 (CAT)进行了比较研究。结果表明 :S1 、S2 和S3CAT活性在 2 5℃、pH 7 0时分别为 41 0 7U/g·FW、 550 4U/g·FW和 370 3U/g·FW ;Km值分别为 5 0× 1 0 ^{- 2}mol/L、 5 4× 1 0 ^{- 2} mol/L和 3 8× 1 0 ^{- 2} mol/L ;最适温度分别为 2 5℃     

杂色云芝产漆酶的发酵条件研究*

本文对杂色云芝（Coriolus versicolor）产漆酶的发酵条件作了研究。结果表明摇瓶实验产漆酶（Laccase）的最佳培养基成分为：可溶性淀粉 2g/L, NH4Cl 24mmol/L, 微量元素混合液 7ml/L, pH3.0柠檬酸—Na2HPO4缓冲溶液 0.01mol/L, KH2PO4 1.4×10-2 mol/L, MgSO4·7H2O 2.03×10-3mol/L, CaCl2·2H2O 6.8×10-4 mol/L, VB1 2.97×10-6 mol/L, 吐温80 4.0g/L, 愈创木酚0.01mmol/L, CuSO4 ·5H2O 0.005mmol/L,最佳发酵条件为培养基初始pH3.0, 菌体生长6d,培养基装量为250ml三角瓶中25ml培养液,25℃条件下振荡培养(150r/min)9d。     

螺旋藻过氧化氢酶的比较研究

采用碘量法对毛乌素沙地碱湖的钝顶螺旋藻S1 与国外引进的钝顶螺旋藻S2 和极大螺旋藻S3 的过氧化氢酶 (CAT)进行了比较研究。结果表明 :S1 、S2 和S3CAT活性在 2 5℃、pH 7 0时分别为 41 0 7U/g·FW、 550 4U/g·FW和 370 3U/g·FW ;Km值分别为 5 0× 1 0 - 2mol/L、 5 4× 1 0 - 2 mol/L和 3 8× 1 0 - 2 mol/L ;最适温度分别为 2 5℃、 2 5℃和 40℃ ;最适pH值分别为 7 2、 7 6和 7 8。内蒙古特有的S1 CAT对温度和pH适应范围宽 ,且在低温、高温和强碱下的活性比引进种的高。     

嗜酸乳杆菌固态发酵的初步研究

研究了嗜酸乳杆菌在 4种不同固态基质 (豆渣、麦麸、芋艿渣、纤维素 )中的生长情况 ,结果显示 :1)豆渣作为基质时嗜酸乳杆菌生长最佳 ,最高活菌数可达 1.6 45× 10 9cfu/g ,麦麸次之 ,达 3.2× 10 8cfu/g ,纤维素最差 ,仅为 2 .1× 10 7cfu/g ,并且豆渣固态培养基优于对照的 3种液体培养基 ;2 )豆渣的含水量以 75 %左右为宜 ;3)通过加入可中和所产酸量的CaCO3 ,并用缓冲液代替水配制培养基 ,结果发现用pH 6 .0的缓冲液配制的培养基 ,培养后活菌量可达 2 .12 4× 10 9cfu/g ,,比对照用自来水提高了 4.2倍 .     

黄嘌呤氧化酶产生菌的离子注入诱变及其二步发酵的研究

采用剂量 1.0× 10 1 2 ～ 1.0× 10 1 6ions cm2 的N+注入产黄嘌呤氧化酶的球形节杆菌ATCC80 10 ,研究其诱变效果。结果表明 :细菌的存活曲线呈现特殊的“马鞍形” ,菌落形态和颜色发生了变化 ,且变化与产酶量有关 ,经过筛选获得了遗传性能稳定的高酶活突变株 ,使酶活较出发菌提高了 43.0 %。改进发酵工艺 ,采用二步发酵其酶得率是一步发酵的 4.75倍。     

弗氏葡糖杆菌产核糖醇脱氢酶研究

目的:研究弗氏葡糖杆菌产核糖醇脱氢酶的培养条件.方法:采用单因素实验研究了葡萄糖、氮源、金属离子Zn2+和Fe3+以及诱导物核糖醇对弗氏葡糖杆菌产酶的影响,并用优化的条件培养产酶进行核糖醇生物转化反应.结果:对于弗氏葡糖杆菌核糖醇脱氢酶的生产,当葡萄糖浓度2.5％、氮源玉米浆粉为1.0％、Zn2+浓度为4 μmol/L、Fe3+浓度为2 μmol/L时,对应的核糖醇脱氢酶活力分别为0.45U/mg、0.43U/mg、0.25U/mg和0.18 U/mg,生物转化验证实验表明反应30 h后核糖醇的转化率达97.73％,质谱分析表明产品符合L-核酮糖的结构.结论:实验获得的优化条件可进一步用于指导生产.     

氮源对谷氨酰胺转胺酶合成的影响

研究不同氮源及培养条件对轮枝链霉菌 (Streptoverticillium)SK - 1合成谷氨酰胺转胺酶 (TGase)的影响 ,结果当以 5 0g/L玉米浆为主要氮源时发酵酶活水平可达 3 0 1μmol/ (min·ml) ;对摇瓶发酵条件进行优化后 ,以 5 0g/L玉米浆为主要氮源 ,起始pH值为 7 0～ 7 5 ,培养温度为 30℃ ,接种量范围为 5 % - 10 % ,培养时间为 38h时 ,酶活最高可达 4 5 2 μmol/ (min·ml) ,酶活提高了5 0 17%。玉米浆作为氮源时发酵酶活比较高 ,发酵时间也较短 ,酶的生产成本较低     

颗粒状固定化青霉素酰化酶的研究

将巨大芽孢杆菌 (Bacillusmegaterium)胞外青霉素酰化酶通过共价键结合到聚合物载体EupergitC颗粒环氧基团上 ,制成的颗粒状固定化青霉素酰化酶表现活力达 1 40 0 μ/g左右。固定化酶水解青霉素的最适 pH8 0 ,最适温度为 55℃。在pH6 0～ 8 5、温度低于 40℃时固定化酶活力稳定。在 pH8 0、温度 37℃时 ,固定化酶对青霉素的表现米氏常数Ka为 2×1 0 - 2 mol/L ;苯乙酸为竞争性抑制剂 ,抑制常数Kip为 2 8× 1 0 - 2 mol/L ;6 APA为非竞争性抑制剂 ,抑制常数Kia为 0 1 2 5mol/L。固定化酶水解青霉素 ,投料浓度为 8% ,在使用 2 0 0批后 ,保留活力 80 %左右 ,6 APA收率平均达 89 48%。     

Cercariometry for detection of transmission sites for schistosomiasis

Cercariometry provided information on diurnal fluctuation, seasonal and spatial distribution of cercariae in the suitable natural water bodies. There was an apparent mismatch between the results of cercariometry and snail sampling. Water, which cercariometry showed to contain cercariae was potentially infective, although the resultant worm load of sentinel rodents may not bear a linear relationship with cercarial density. Cercariometry has some weakness in practices and analysis of data, however, it provides the valuable information on the active transmission sites of schistosomiasis.     

Risk factors for rejection for morphological reasons of heart valves for transplantation

The study aim was to identify risk factors for morphological rejection of aortic and pulmonary valves for transplantation that could be used to optimize donor selection. The files of all Dutch heart valve donors, donating in a 2.5 years period, whose hearts were processed at Heart Valve Bank Rotterdam, were reviewed for all factors that could be relevant for valve rejection and related to outcome of morphological assessment of the valves. Valves were retrieved from 813 deceased Dutch donors, 24.1% also donating organs. For 797 aortic and 767 pulmonary valves, who met retrieval criteria, morphological assessment was done. 69.5% of aortic and 37.5% of pulmonary valves were considered unsuitable for transplantation at morphological assessment. Backward stepwise multivariate logistic regression analysis, showed age, cardiac cause of death, cerebrovascular accident as cause of death or in medical history, and number of cardiovascular risk factors in a donor to be independent risk factors for morphological rejection of aortic valves. Age, sex, weight >100 kg and ruptured aortic aneurysm as cause of death were independent risk factors for morphological rejection of pulmonary valves. Being an organ donor was an independent predictor of morphological approval of aortic and pulmonary valves, while hypertension was an independent predictor for morphological approval of aortic valves. Thus, independent factors were identified that are associated with morphological rejection of aortic and pulmonary valves for transplantation, and that could be used to optimize donor selection by preventing unnecessary retrievals, limiting costs, while improving yield per donor with minimal compromise for availability.     

Prospects for use of iodine-free radiopaques for cholecystocholangiography

By using the compounds tantalum and lanthanum, a new radiopaque substance (ROS) was synthesized at the Institute for Chemistry of Solids, Urals Branch of the Russian Academy of Sciences. Experiments on laboratory animals provided evidence that there was no acute or chronic toxicity of helium-based lanthanum orthotantalate. The specific radiopaque properties of the agent versus iodine- and barium-containing ROSs were studied in in vitro and in vivo experiments. The radiodiagnostic properties and locally irritant effect of the test ROS versus iodine-containing agents were evaluated in dogs at cholecystocholangiography.     

Method for epitope selection of antisera for immunohistology

Polyclonal anti-laminin serum was affinity-purified on paraformaldehyde-fixed laminin on a nitrocellulose filter. The purified antibodies were tested for their specificity in immunohistological stainings on frozen sections of paraformaldehyde-fixed tissue. As compared to the initial polyclonal serum, the purified antibodies increased the specificity of antigen detection, since all background caused by nonspecific reactions was eliminated. This technique promises to be very useful for immunohistological analysis using light and electron microscopy.     

Standards for Approval of Hospitals for Graduate Training

The assessment program for approval of hospitals for training in specialties has been augmented by survey visits. Surveyors for the Canadian Council on Hospital Accreditation have acted on behalf of the Royal College of Physicians and Surgeons of Canada and have assisted in the formulation of standard criteria for evaluation of teaching programs. Areas where considerable variation in program exists and where further standardization might profitably be developed are suggested. It is recommended that periodic on-the-site visits be made to all specialty training hospitals. Standards should be further elucidated to guide teachers, students and Royal College surveyors alike. It is emphasized that standards cannot be used to assess the calibre of teaching and learning, but can be employed to assist in evaluating the teachings and learning media that are likely to produce good (or poor) results.     

A checklist for ecological management of landscapes for conservation

The management of landscapes for biological conservation and ecologically sustainable natural resource use are crucial global issues. Research for over two decades has resulted in a large literature, yet there is little consensus on the applicability or even the existence of general principles or broad considerations that could guide landscape conservation. We assess six major themes in the ecology and conservation of landscapes. We identify 13 important issues that need to be considered in developing approaches to landscape conservation. They include recognizing the importance of landscape mosaics (including the integration of terrestrial and aquatic areas), recognizing interactions between vegetation cover and vegetation configuration, using an appropriate landscape conceptual model, maintaining the capacity to recover from disturbance and managing landscapes in an adaptive framework. These considerations are influenced by landscape context, species assemblages and management goals and do not translate directly into on-the-ground management guidelines but they should be recognized by researchers and resource managers when developing guidelines for specific cases. Two crucial overarching issues are: (i) a clearly articulated vision for landscape conservation and (ii) quantifiable objectives that offer unambiguous signposts for measuring progress.     

Nonlinear electrophoresis for purification of soil DNA for metagenomics

Purification of microbial DNA from soil is challenging due to the co-extraction of humic acids and associated phenolic compounds that inhibit subsequent cloning, amplification or sequencing. Removal of these contaminants is critical for the success of metagenomic library construction and high-throughput sequencing of extracted DNA. Using three different composite soil samples, we compared a novel DNA purification technique using nonlinear electrophoresis on the synchronous coefficient of drag alteration (SCODA) instrument with alternate purification methods such as direct current (DC) agarose gel electrophoresis followed by gel filtration or anion exchange chromatography, Wizard DNA Clean-Up System, and the PowerSoil DNA Isolation kit. Both nonlinear and DC electrophoresis were effective at retrieving high-molecular weight DNA with high purity, suitable for construction of large-insert libraries. The PowerSoil DNA Isolation kit and the nonlinear electrophoresis had high recovery of high purity DNA suitable for sequencing purposes. All methods demonstrated high consistency in the bacterial community profiles generated from the DNA extracts. Nonlinear electrophoresis using the SCODA instrument was the ideal methodology for the preparation of soil DNA samples suitable for both high-throughput sequencing and large-insert cloning applications.     

Algorithms for mapping of mRNA targets for microRNA

MicroRNAs (miRNAs) are involved in human health and disease as endogenous suppressors of the translation of coding genes. At this early point of time in miRNA biology, it is important to identify specific cognate mRNA targets for miRNA. Investigation of the significance of miRNAs in disease processes relies on algorithms that hypothetically link specific miRNAs to their putative target genes. The development of such algorithms represents a hot area of research in biomedical informatics. Lack of biological data linking specific miRNAs to their respective mRNA targets represents the most serious limitation at this time. This article presents a concise review addressing the most popular concepts underlying state-of-the-art algorithms and principles aimed at target mapping for specific miRNAs. Strategies for improvement of the current bioinformatics tools and effective approaches for biological validation are discussed.