阿魏菇多糖高产菌的离子束和激光复合诱变育种

目的:诱变筛选阿魏菇多糖高产菌,探索食用菌的离子束和激光复合诱变育种方法。方法:尝试用阿魏菇菌丝单细胞为靶材,以离子束注入和激光辐照为复合诱变手段,采用营养缺陷型筛选办法定性初筛,摇瓶发酵定量复筛。结果:通过离子束注入诱变,获得了2株菌丝体多糖产量分别达到551.80mg/L和659.46mg/L、较1号出发菌株提高了46.5%和75.2%的多糖高产菌PFPH-1和PFPH-2;在此基础上,以激光辐照为复合诱变手段,获得了1株菌丝体多糖产量达到762.50 mg/L、较出发菌株PFPH-2提高了15.63%的多糖高产菌PFPH-3。结论:离子束和激光复合诱变育种方法在改良阿魏菇多糖高产性状方面诱变功效显著。     

密环菌胞外多糖的发酵条件研究

密环菌是天麻的共生菌,有研究证明,密环菌的菌丝及发酵液有与天麻相类似的药理作用,为此,我们进行密环菌深层发酵产胞外多糖条件的研究。研究结果表明：菌丝生长和多糖产生的最适初始pH为5．9左右;消泡剂用量在一定内增加,有利于菌丝的生长,但增加消泡剂用量会不利于多糖的产生;接种量大,菌丝得率高,但接种量为10％时的多糖得率最高;装液量试验表明,通气量大,有利于菌丝的生长和多糖的产生;机械搅拌对菌丝的生长和多糖的产生都不利;生长动态实验证明,密环菌可在6d内完成液体发酵;以豆粕粉作氮源时,菌丝得率最高,以麸皮作氮源时,多糖产量最高;红薯粉为密环菌菌丝生长和多糖产生的最适碳源。     

低能离子束生物技术的应用

自从我国科学家发现离子注入生物学效应后,低能离子束生物技术的研究就在我国率先兴起。随后,越来越多的科学家基于低能离子与生物体之间存在的能量沉积、动量传递、质量沉积及电荷中和与交换的相互作用,对生物体内的遗传物质进行加工、修饰、重组,开辟了农作物和微生物等遗传改良及转基因的新方法。本文简要介绍了低能离子束生物技术产生的背景、低能离子束与生物体之间相互作用的机理和特点以及目前低能离子束在诱变育种和转基因等生物技术领域的研究进展,并展望了离子束技术在藻类基因工程方面的发展潜力。     

N~+离子诱变高效降酚菌及其含酚废水模拟处理的研究

取降酚效果较好菌株E为诱变出发菌株,利用N+离子束诱变,获得若干突变菌株,计算诱变存活率和正突变率,利用正交实验对离子束诱变的优势菌KE2菌株进行了最适宜生长条件的优化,并进行实验室模拟实验.结果表明诱变注入的较适宜剂量为18.4×1014N+/cm2.诱变菌株中降酚效果最好的诱变菌KE2的降酚率较出发菌E高,且在传代时性状稳定.经初步鉴定,出发菌株E和诱变降酚菌KE2属于假单胞菌(Pseudo-monas.sp.).KE2降酚诱变菌的生长适宜参数为:葡萄糖浓度1 000 mg/L,pH值为7,温度30℃.实验室模拟实验显示,添加诱变菌株的一组降酚效果较好,在500 mg/L的酚浓度下,9 h降酚率可达到100%,1 000 mg/L的酚浓度下,加诱变菌组在12 h可完全降解,达到100%.     

高产腈水解酶Alcaligenes faecalis ULA4菌株的诱变筛选

应用紫外-氯化锂和低能离子束复合诱变的方法,对1株本实验室筛选得到并保藏的腈水解酶产生菌Alcaligenes faecalis ZJB09133进行诱变育种,筛选到高产菌株UL44,其腈水解酶酶活达到74.6 U/g,较出发.菌株酶活提高124.5％.得到的高产菌株UL44经过5次传代,其遗传稳定性良好.     

复合诱变选育绿色产色链霉菌抑菌高活性菌株

以一株绿色产色链霉菌xzte06菌株为出发菌株,依次通过软X射线、低能离子束诱变、紫外线照射和微波诱变手段对菌株进行复合诱变,得到一株对产气荚膜梭状芽胞杆菌具有较强抑制活性的菌株W26菌株,且该菌株的遗传特性稳定。对菌株进行抑菌试验发现,该菌株液体深层发酵菌丝体的内酮提取物的抑菌活性与出发菌株相比提高了101.42%。     

低能重离子在作物种胚内射程分布的研究技术

我国科学工作者率先将低能重离子束成功地应用于作物诱变育种,并建立了能量,质量和电荷三因子作用机制体系,但至今有关理论射程很短的低能重离子注入生物体后如何通过信息传递而诱发生物学效应的机理尚不完全清楚,低能重离子在作物种胚内的实际射程分布迄今仍是一个颇有争议的热点问题,而该项研究就直接触及低能离子束与生物组织细胞的原初作用机制,应用低能放射性束或具有可探测放射性的核反应产物,通过超薄切片和逐层分析测定,即可定量计算不同能量的低能离子束在作物种胚内的射程分布,本文还探讨了激光共聚焦扫描显微镜,原子力显微镜,X-射线能谱分析技术,单粒子微束技术和图像处理等技术途径在该项研究中的应用。     

我国猪苓研究的进展

猪苓菌核同密环菌建立起共生关系才能继续生长。从猪苓菌核生长、菌核与蜜环菌的关系、猪苓菌种培养与猪苓多糖提取、猪苓人工栽培等方面进行了综述     

人工蝉花孢梗束粗多糖的提取工艺和活性

通过单因素试验和正交试验研究了人工蝉花孢梗束粗多糖的提取工艺,并通过粗多糖对果蝇寿命、果蝇体内SOD活性及MDA含量的影响研究了粗多糖的活性。试验结果表明:人工蝉花孢梗束粗多糖的最佳提取工艺为液料比20∶1、时间2 h、温度90℃、浸提2次、醇沉乙醇浓度70%、醇沉时间为24 h;在该条件下的粗多糖得率为8.65%。孢梗束粗多糖能明显延长雌雄果蝇的寿命,延长率分别为18.78%和26.23%;孢梗束粗多糖能显著提高雌雄果蝇的SOD活性,并明显降低了雄性果蝇体内MDA含量,说明人工蝉花孢梗束粗多糖具有抗氧化活性和延长果蝇寿命的作用。     

蛹虫草多糖对果蝇寿命影响的研究

研究了蛹虫草多糖对果蝇寿命的影响.实验结果表明:蛹虫草多糖可明显延长果蝇的最高寿命、平均寿命及半数死亡时间,具有显著的抗衰延寿作用.其中,浓度为0.15%的蛹虫草多糖可使雌性果蝇的最高寿命延长率达21.77%;使雌雄果蝇的平均寿命延长率分别达34.35%和11.24%;使雌雄果蝇的半数死亡时间延长率分别为61.76%和23%.但是蛹虫草多糖对果蝇的延寿作用并不随培养基中虫草多糖浓度的提高而增强,只有在适当的浓度下,才能表现出显著的延寿效果.     

Immunogold determination of amylase concentrations in pancreatic subcellular compartments

We used the immunogold method on ultrathin cryosections to measure intracellular amylase (Am) concentrations in subcellular compartments of rat exocrine pancreatic cells. Previously, the quantitation procedure was characterized in a model system consisting of Am dispersed at known concentration in a matrix of gelatin. Variations in labeling efficiency, due to differences in matrix density, were equalized by embedding in 30% polyacrylamide (PAA). Here we applied these model conditions to rat pancreas and established intracellular Am concentrations [Am]. Specimen blocks were composed of tissue and a reference layer of gelatin mixed with a known Am concentration ([Am]r), both fixed in glutaraldehyde. Cryosections of the PAA embedded blocks were immunogold labeled for Am. The labeling density was measured in the reference layer (LDr) and in structures in exocrine cells that were involved in Am synthesis and transport (LDs). In each of these structures the Am concentration ([Am]s) was calculated from: [Am]s = [Am]r. LDs/LDr In this way we measured average concentrations ranging from 63 mg/ml in rough endoplasmic reticulum to 261 mg/ml in secretory granules. Concentration of Am appeared to occur mainly in the most cis- and the most trans-Golgi cisternae. To check whether sterical hindrance was an inherent bias to the [Am] measurements in compartments that contained high concentrations of the enzyme, the labeling efficiency for Am in intact isolated secretory granules in gelatin and embedded in PAA, was compared with the efficiency when the granules were lysed and approximately 50 times diluted in gelatin before PAA embedment. It appeared that Am was detected with similar efficiency under both conditions. This demonstrated that sterical hindrance did not cause errors in the measurements of cellular Am concentrations.     

Experimental investigations of 211Am accumulation by macrophytes of the Yenisei River

Experiments were carried out in which 241Am was added to water samples containing macrophytes of the Yenisei River, and the radionuclide absorption rates and concentration factors were determined for the plants. It has been shown that the water moss (Fontinalis antipyretica) has a higher capacity to accumulate 241Am than the Canadian pondweed (Elodea canadensis) does. The laboratory experiments revealed that the capacity of dead biomass of the Canadian pondweed to accumulate 241Am is twice higher than that of living biomass. In contrast, no significant increase in 241Am accumulation by dead biomass of the water moss has been recorded. The transuranic element 241Am was firmly fixed by the plant biomass and was not released into water in the course of long-duration experiments.     

The genetic polymorphism of the blood proteins in RID-positive reacting cows]

Cattle herd of Black-and-White, Red and Simmental breeds having positive or negative RID-reaction to leucosis was studied as to the polymorphism of serum blood proteins in three loci: Tf, Am and Cp. One system of polymorphic proteins has been determined as having a higher concentration of homozygotes (Tf) and another one as having a higher concentration of heterozygotes (Am) within one and the same herd among animals with the positive RID-reaction.     

Epigenetic Control of a Transposon-Inactivated Gene in Neurospora Is Dependent on DNA Methylation

An unstable allele of the Neurospora am (GDH) gene resulting from integration of the retrotransposon Tad3-2 into 5'' noncoding sequences was found in previous work. We report that reversion to Am(+) depends on DNA methylation within and upstream of Tad. Levels of methylation were correlated with the proportion of Am(+) conidia, whether the cultures were derived from Am(-) or Am(+) isolates. Reversion to Am(+) did not occur when conidia were plated on 5-azacytidine, which reduces DNA methylation. The mutation dim-2, which appears to abolish DNA methylation, also prevented reversion to Am(+). The native am allele, in a strain that lacked Tad elements, was replaced with am::Tad3-2 or with a deletion derivative that prevents transposition of Tad. Transformants of both classes showed instability comparable with that of the original isolates, which contain multiple Tad elements. Deletion of the upstream enhancer-like sequences, URSamα and β, did not prevent the instability of am::Tad3-2. The results suggest that am expression is dependent on DNA methylation but not on proliferation or transposition of the Tad element and that the instability does not require the upstream sequences of am.     

The accumulation of 241Am by suspended matter of the Yenisei River

Laboratory experiments were performed to determine parameters of accumulation of 241Am by suspended particulate matter (seston) of the Yenisei River, with particles larger than 1 microm, and the diatoms A. formosa and D. vulgare. Concentration factors for seston were (2.8-4.1) x 10(5) and for diatoms--(1.5-4.2) x 10(4). As phytoplankton's contribution to the seston mass is rather small (< 10%), we assume that suspended matter contains other particles similar in size to the Yenisei River phytoplankton, which make larger contribution to 241Am concentration of seston than the studied algae. No energy-dependent accumulation of americium by algae was detected in the experiments. Addition of dissolved organics and hydrogen carbonates led to a lower uptake of 241Am from the Yenisei water by seston.     

Polarity of amber mutations in ribosomal protein genes of Escherichia coli.

Two amber mutations have been mapped inside the spcA-strA region (now called rpsE-rpsL) on the bacterial genome. Derivatives of the transducing phage lambda fus3 carrying each mutation were constructed and assayed in ultraviolet-irradiated bacteria to identify the mutated genes and measure the polarity of the mutations. The data indicated that both mutations, 3162(Am) and 3161(Am), affect genes coding for ribosomal proteins: rplC (L3) and rpsN (S14), respectively. It was shown also that each mutation exerts, inside of its respective operon (S10 and spc units), a relatively strong polar effect on genes distal to the mutated locus.     

dnaB analog function associated with plasmid R100drd-1.

Plasmid R100 and a number of its derivatives were able to suppress the temperature sensitivity of strains carrying different alleles of the dnaB gene of Escherichia coli K-12. R100drd-l and pAR132 were able to rescue a strain carrying the dnaB266(Am) mutation in the absence of any known amber suppressors. This was taken as evidence for the existence of an R100drd-l dnaB analog function. The R100drd-l dnaB analog was different from those of bacteriophages P1 and P7 in that it was able to support the growth of bacteriophage lambda in a dnaB266(Am) background. The dnaB analog was also shown to be thermosensitive. The structural gene for this protein lies within the EcoRI fragment D of R100drd-l.     

Differential enhancement of spontaneous transition mutations in the lacI gene of an Ung- strain of Escherichia coli

In this communication, the contribution of cytosine deamination to spontaneous mutagenesis in the lacI gene of E. coli was examined. In a wild-type strain, 75% of the amber mutations recovered were G:C----A:T transitions and 60% of these were at the 5-methylcytosine spontaneous hotspots Am6, Am15 and Am34. In a strain deficient for uracil-DNA glycosylase (Ung-), 96% of the amber mutations were G:C----A:T transitions while only 15% of these occurred at the hotspot sites. This shift in the mutational distribution demonstrates that cytosine deamination is a potent mutagenic process, which is enhanced in the absence of glycosylase. Moreover, some amber sites were greatly enhanced in the Ung- strain while others were only slightly enhanced. This result suggests that the rate of cytosine deamination at individual sites may be influenced by surrounding base composition. Therefore, we examined the neighboring sequences and found a strong correlation between the fold-increase in mutation and the A/T richness of the surrounding sequence. It is suggested that A/T-rich regions denature more often, forming transient single strands in which cytosine residues would be expected to deaminate more readily.     

结核分枝杆菌临床株4种耐药基因的检测与分析

结核分枝杆菌Mycobacterium tuberculsis(M.t)4种耐药基因的研究,了解耐药基因突变情况和耐药水平的关系。108例临床痰标本临床分离株均做传统梯度药敏试验和聚合酶链反应多态-单链构象多态性（PCR-SSCP）试验。结果表明耐SM（rpsL）REP(rpoB）INH(katG）EMB（embB）基因突变率分别为78.5%,68.2%,70.5%,48.6%。其中,上海高耐药株基因突变率分别为86.5%,89.3%,84.3%,35.3%。低耐药株分别为28.5%,16.5%,7.1%。EMB在低耐药区无基因突变。M.t的4种耐药基因联合检测的分析,在国内外很少报道。部分M.t的耐药由耐药基因突变所致,M.t耐药基因突变与耐药水平密切相关,且M.t基因突变绝大多数发生在高耐药区中,也有少部分在低耐区株中发生。