纳他霉素产生菌基因组重排育种

Streptomyces gilvosporeus SG-1原生质体经紫外线诱变并筛选链霉素抗性菌株，获得纳他霉素高产菌株。在上述高产突变株中选择4株作为亲本进行基因组重排育种，筛选得到了高产重排菌株，其中一株重排菌株S．gilvosporeus GS-74的纳他霉素产量为3574mg／L。为产量最高的亲本菌株的153％，比原始出发菌株SG-1提高1.17倍。     

通过获得链霉素抗性基因(str)突变株筛选梅岭霉素高产菌株

本文通过链霉素对梅岭霉素（meilingmycin）产生菌南昌链霉菌NS－41－80菌株孢子致死浓度的测定，采用诱变剂EMS四种不同诱变剂量对菌株的孢子进行诱变处理，诱变处理的孢子涂布在含链霉素致死浓度的高氏平板上，获得了大量的链霉素抗性基因（str）突变株。然后从链霉素抗性基因突变株进一步筛选到梅岭霉素高产菌株80－5．11－221，在摇瓶条件下，只产梅岭霉素不产南昌霉素，梅岭霉素活性效价达1500μg/ml，比出发菌株NS－41－80的摇瓶发酵效价855μg/ml提高了77．9％，该菌株连续传代六代进行摇瓶发酵，其F2代和F3代梅岭霉素发酵效价稳定，F4代至F6代随着传代数增加，其梅岭霉素发酵效价急速下降。通过EMS诱变剂量分别与抗药性突变率和链霉素抗性基因突变株产梅岭霉素产量的产势统计分析表明，菌株抗药性突变与产抗生素突变密切相关，产抗生素突变的EMS诱变剂量高于链霉素抗性基因突变诱变剂量。在0．03mol/L的EMS剂量作用下，菌株致死率为99．43％，而抗药性突变率为0．0440％，建立了梅岭霉素产生菌链霉素抗性基因突变筛选方法，为南昌链霉菌高产菌种选育研究作了有益的尝试，并有助于其它链霉菌属的抗生素产生菌育种研究。     

组合抗性筛选法选育达托霉素高产菌株

目的利用组合抗性筛选法选育达托霉素高产菌株。方法以玫瑰孢链霉菌(Streptomyces roseosporus ATCC 11379)为出发菌株,通过在不同浓度梯度的达托霉素和链霉素复合抗性平板上进行抗性筛选。结果筛选到一株高产达托霉素的突变株D1000-S3-2,经摇瓶发酵验证达托霉素发酵单位可达59mg/L,比出发菌株提高了63.8%。结论实验证明组合抗性筛选是一种简单高效筛选方法。     

纳他霉素高产菌株的链霉素抗性选育及其发酵工艺的优化

用紫外线对纳他霉素(Natamycin)产生菌褐黄孢链霉菌(Streptomyces gilvosporeus)ATCC13326菌株孢子进行诱变处理后，利用链霉素抗性突变选育得122株链霉素抗性突变株。其中纳他霉素产量高于出发菌株的有13株。突变株SG-56的生产能力达到出发菌株的146％，研究了其发酵性能，优化了培养基组成和发酵工艺条件，纳他霉素产量为2．81g／L，较出发菌株产量提高了170％。     

60Co诱变选育平阳霉素高产株的研究

目的 筛选平阳霉素高产菌株。方法 以平阳霉素产生菌-平阳链霉菌为出发菌株,采用60C0诱变处理并通过遥瓶试验。结果 获得一株高产突变株,其产素能力达到出发菌株效价的1.86倍。传代试验表明该突变株的高产遗传特性稳定。结论     

ARTP诱变结合抗性筛选选育西索米星高产菌株

目的 利用等离子体诱变,结合抗生素抗性筛选,获得西索米星高产菌株。方法 首先通过链霉素抗性筛选,获得一株比出发菌株产抗能力高的S4;随后以S4为出发菌株,经等离子体处理40s,借助巴龙霉素抗性筛选,得到双重抗性菌株。最后对突变株进行再次诱变,并结合高浓度链霉素抗性筛选。结果 获得一株高产突变株M. inyoensis SAAP22,比出发菌株效价提高了38.18%,具有稳定的遗传性能。结论 通过等离子体诱变,结合抗生素抗性筛选,可有效提升伊尼奥小单孢菌的西索米星合成能力,所得高产菌株具有潜在应用价值。     

盐霉素自身抗性高产突变菌株筛选

目的筛选出具有自身次级代谢产物盐霉素(salinomycin)抗性并且遗传稳定性好的菌株,提高摇瓶效价。方法采用常规化学试剂甲基磺酸乙酯诱变处理盐霉素生产菌株Streptomyces albus S-13孢子,通过系列salinomycin浓度梯度平板进行筛选。结果获得了比生产对照菌株高38%的突变株S-E-6。传代实验表明:S-E-6具有较好的遗传稳定性。同时,通过对盐霉素梯度筛选突变株的单菌落直径与效价进行了统计分析,结果表明突变株菌落直径与盐霉素效价具有正相关特性,线性相关系数(R2)为0.95。     

链霉菌702抗药性致死突变标志微波诱变筛选研究

目的 筛选出产抗真菌活性物质的高产链霉菌702突变株.方法 分别以链霉菌702菌株为试验材料和以庆大霉素为敏感抗生素建立链霉菌702孢子致死突变标志的微波诱变筛选模型,通过微波对链霉菌702菌株孢子进行不同时间的诱变处理,将诱变处理后的孢予悬液涂布于含致死浓度的庆大霉素的PDA平板培养基上,获得抗庆大霉素突变株,分别挑取单个抗药性突变菌株进行摇瓶初筛和复筛.生物效价测定采用一剂量法.结果 微波处理30s对菌株的致死率可达70.53%,抗药性突变率高达23.13%,获得的抗药性突变株经过摇瓶初筛和复筛,获得高产突变株20-29-47菌株,产抗真菌活件物质的摇瓶发酵单位达到1478μg/ml,比出发菌株发酵单位986μg/ml提高T49.9%.结论 采用抗药性致死突变标志的微波诱变筛选模型可以获得产抗真菌活性物质的链霉菌702高产菌株.     

A82846B生产菌株选育及发酵培养基的优化

以荒漠拟孢囊菌SIPI-HT47为出发菌株,发酵合成奥利万星中间体A82846B。应用紫外和NTG诱变,结合自身抗性及氯化盐耐受筛选,获得1株高产突变株,命名为FH-32-322,发酵效价较出发菌株提高172.5%。通过PB试验、爬坡试验和响应面试验设计优化发酵培养基组成,确定最佳摇瓶发酵配方。在优化后的发酵培养基上,突变株FH-32-322摇瓶发酵效价达到1 013 mg/L,较原工艺提高85.9%。     

链霉素抗性突变-万古霉素高产菌株的选育研究

以东方拟无枝酸菌(Amycolatopsis orientalis)AO-4为出发菌株，经紫外线(15w，253．7nm，距离30cm)诱变处理，筛选链霉素抗性突变株(链霉素浓度1000μg／ml)，从中获得万古霉素高产变株Amycolatopsis orientalis AO-29，其发酵效价较出发菌株提高170%。传代实验表明该变株的高产性能遗传特性较稳定。     

Efficacy of gut lavage,hemodialysis, and hemoperfusion in the therapy of paraquat or diquat intoxication

Clinical and in vitro investigations were carried out to test the efficacy of gut lavage, hemodialysis, and hemoperfusion in the treatment of poisoning with paraquat or diquat. In a patient suffering from diquat intoxication 130 times more diquat was removed by gut lavage 30 h after ingestion than was removed by complete aspiration of the gastric contents.Determination of in vitro clearances for paraquat and diquat by hemodialysis showed that, at serum concentrations of 1–2 ppm, such as are frequently encountered in poisoning in man, toxicologically relevant quantities of herbicide cannot be removed from the body. At a concentration of 20 ppm, on the other hand, hemodialysis proved to be effective, the clearance being 70 ml/min at a blood flow rate of 100 ml/min. The efficacy of hemoperfusion with coated activated charcoal was on the whole better. Especially at concentrations around 1–2 ppm, the clearance values for hemoperfusion were some 5–7 times higher than those for hemodialysis.In a patient suffering from paraquat poisoning, both hemodialysis as well as hemoperfusion were carried out. The in vitro results could be confirmed: At serum concentrations of paraquat less than 1 ppm no clearance could be obtained by hemodialysis while by hemoperfusion with activated charcoal quite high clearance values were measured and the serum level dropped down to zero.

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Zusammenfassung Klinische Untersuchungen und Laboratoriumsversuche wurden durchgeführt, um die Wirksamkeit von Darmspülung, Hämodialyse und Hämoperfusion bei Paraquat- und Deiquat-Vergiftungen zu prüfen.Bei einem Patienten wurde 30 Std nach Deiquat-Aufnahme durch Darmspülung 130mal mehr Deiquat entfernt als durch vollständige Aspiration des Mageninhaltes. In vitro-Versuche ergaben, daß bei Blutserumkonzentrationen von 1–2 ppm, die bei Vergiftungen oft gemessen werden, durch Hämodialyse keine toxikologisch relevanten Paraquat- oder Deiquat-Mengen entfernt werden können. Dagegen erwies sich die Hämodialyse bei 20 ppm und einer Blutumlaufgeschwindigkeit von 100 ml/min mit einer Clearance von 70 ml/min als wirksam. Die Hämoperfusion mit beschicheter Aktivkohle war in diesen Versuchen aber eindeutig überlegen, denn insbesondere bei Konzentrationen um 1–2 ppm waren die Clearance-Werte 5–7mal höher als bei der Hämodialyse.Die in vitro-Ergebnisse wurden bei einem Patienten mit einer Paraquat-Vergiftung bestätigt: Bei Konzentrationen unter 1 ppm war die Hämodialyse wirkungslos, während durch Hämoperfusion relativ hohe Clearance-Werte erreicht wurden, so daß der Serumspiegel rasch unter die Nachweisgrenze abfiel.

     

In vitro studies on sterically stabilized liposomes (SL) as enzyme carriers in organophosphorus (OP) antagonism

This study describes a new approach for organophosphorous (OP) antidotal treatment by encapsulating an OP hydrolyzing enzyme, OPA anhydrolase (OPAA), within sterically stabilized liposomes. The recombinant OPAA enzyme was derived from Alteromonas strain JD6. It has broad substrate specificity to a wide range of OP compounds: DFP and the nerve agents, soman and sarin. Liposomes encapsulating OPAA (SL)* were made by mechanical dispersion method. Hydrolysis of DFP by (SL)* was measured by following an increase of fluoride ion concentration using a fluoride ion selective electrode. OPAA entrapped in the carrier liposomes rapidly hydrolyze DFP, with the rate of DFP hydrolysis directly proportional to the amount of (SL)* added to the solution. Liposomal carriers containing no enzyme did not hydrolyze DFP. The reaction was linear and the rate of hydrolysis was first order in the substrate. This enzyme carrier system serves as a biodegradable protective environment for the recombinant OP-metabolizing enzyme, OPAA, resulting in prolongation of enzymatic concentration in the body. These studies suggest that the protection of OP intoxication can be strikingly enhanced by adding OPAA encapsulated within (SL)* to pralidoxime and atropine.     

Aquatic Insects and Trace Metals: Bioavailability,Bioaccumulation, and Toxicity

Abstract

The uptake of metals from food and water sources by insects is thought to be additive. For a given metal, the proportions taken up from water and food will depend both on the bioavailable concentration of the metal associated with each source and the mechanism and rate by which the metal enters the insect. Attempts to correlate insect trace metal concentrations with the trophic level of insects should be made with a knowledge of the feeding relationships of the individual taxa concerned. Pathways for the uptake of essential metals, such as copper and zinc, exist at the cellular level, and other nonessential metals, such as cadmium, also appear to enter via these routes. Within cells, trace metals can be bound to proteins or stored in granules. The internal distribution of metals among body tissues is very heterogeneous, and distribution patterns tend to be both metal and taxon specific. Trace metals associated with insects can be both bound on the surface of their chitinous exoskeleton and incorporated into body tissues. The quantities of trace meals accumulated by an individual reflect the net balance between the rate of metal influx from both dissolved and particulate sources and the rate of metal efflux from the organism. The toxicity of metals has been demonstrated at all levels of biological organization: cell, tissue, individual, population, and community. Much of the literature pertaining to the toxic effects of metals on aquatic insects is based on laboratory observations and, as such, it is difficult to extrapolate the data to insects in nature. The few experimental studies in nature suggest that trace metal contaminants can affect both the distribution and the abundance of aquatic insects. Insects have a largely unexploited potential as biomonitors of metal contamination in nature. A better understanding of the physico-chemical and biological mechanisms mediating trace metal bioavailability and exchange will facilitate the development of general predictive models relating trace metal concentrations in insects to those in their environment. Such models will facilitate the use of insects as contaminant biomonitors.     

Alzheimer’s disease – current trends in basic and clinical research. Highlights from the 16th ECNP

Advances in the molecular biological knowledge of neuronal nicotinic acetylcholine receptors (nAChRs) have led to a growing interest by the pharmaceutical industry in the development of novel compounds that selectively modulate nAChR function. The ability of (-)-nicotine, an activator of nAChRs, to enhance attentional aspects of cognition in animals and humans, to exert neuroprotective and anxiolytic-like effects, and presumably to mediate the negative correlation between smoking and Alzheimer's (and Parkinson's) Disease, has focused interest on the potential therapeutic utility of modulators of nAChR function for treatment of some of the deficits associated with these progressive, neurodegenerative conditions. Numerous compounds are known which activate nAChRs and which might serve as lead compounds toward the development of such agents. The pharmacologic diversity of neuronal nAChR subtypes suggests the possibility of developing selective compounds which would have more favourable side-effect profiles than existing agents. This broader class of agents, collectively called cholinergic channel modulators (ChCMs), is anticipated to encompass compounds which would have more favourable side-effect profiles than existing agents, which generally exhibit low selectivity. This selectivity may be achieved by preferentially activating some subtypes of nAChRs (i.e., Cholinergic Channel Activators, ChCAs) or inhibiting the function of other subtypes (Cholinergic Channel Inhibitors, ChCIs). An overview of the biology of nAChRs and the rationale for the use of ChCMs for the treatment of dementia related to neurodegenerative diseases are presented, followed by a discussion of lead compounds and compounds under consideration for clinical evaluation.     

Steroidal sapogenin contents in some domestic plants

In order to find out the values of the steroid resources for the future use. the compositions and contents of steroidal sapogenins from 13 domestic plants have been investigated. As a result,Dioscorea nipponica, D. quinqueloba andSmilax china were found to have large amount of diosgenin. And pennogenin inTrillium kamtschaticum andParis verticillata, yuccagenin inAllium fistulosum, hecogenin inAgave americana and neochlorogenin inSolanum nigum were appeared to be major steroidal sapogenins.