禾本科植物内生菌研究进展

从19世纪到现在,国际上已有许多关于植物内生菌的研究报道,无论是它在草坪草和牧草中的生态经济价值,还是它所涉及相关领域如医学、病理,都引起人们对它的重视和关注.综述了禾本科内生菌的种类、抗性机制及其应用,并据此提出了关于内生菌研究的一些问题,从而为进一步研究内生菌在禾本科植物中的作用提供参考.     

Characterization of horse spleen apoferritin reactive lysines by MALDI-TOF mass spectrometry combined with enzymatic digestion

Ferritins are a class of iron storage protein spheres found mainly in the liver and spleen, which have attracted many research interests due to their unique structural features and biological properties. Recently, ferritin and apoferritin (ferritin devoid of the iron core), have been employed as chemically addressable nanoscale building blocks for functional materials development. However, the reactive residues of apoferritin or ferritin have never been specified and it is still unclear about the chemoselectivity of apoferritin towards different kinds of bioconjugation reagents. In this work, matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry combined with enzymatic digestion analysis was used to identify the reactive lysine residues of horse spleen apoferritin when conjugated with N-hydroxysuccinimide reagents. The result demonstrated that among all the lysine residues, K97, K83, K104, K67 and K143 are the reactive ones that can be addressed.     

Potential of Ipomoea aquatica cultivars in phytoremediation of soils contaminated with di-n-butyl phthalate

Five different genotypic cultivars of Ipomoea aquatica commonly grown in Southeast Asia were cultivated to investigate their accumulation variation of di-n-butyl phthalate (DBP) and their potential for phytoremediation of three soils contaminated with DBP (4.5, 10.3 and 22.5 mg kg^?1). The results indicated different cultivar tolerance to DBP. DBP concentration in the shoots of the cultivars and residual DBP concentration in the soil were proportional to initial DBP concentrations in the soil and significantly different with different genotypic cultivars, indicating that the removal of DBP is cultivar-specific. DBP removal in the soil with indigenous DBP was higher than that in freshly DBP-spiked soils. The cultivars of local white-skin I. aquatica (cultivar V₅) and Taiwan filiform-leaf I. aquatica (cultivar V₁) presented the highest phytoremediation potential in the soil containing indigenous DBP and in freshly DBP-spiked soil, respectively. The translocation factor (TF, DBP concentration ratio of the shoots to the roots) and bioconcentration factor (BCF, DBP concentration ratio of the plant to the soil) also significantly varied with different cultivars, and they did not follow distribution profiles correlated to DBP removal indicating that phytoextraction was not the dominant DBP removal mechanism. Finally, the potential ability of different cultivars of enhancing biodegradation varied widely.     

Characterization of replication and conjugation of Streptomyces circular plasmids pFP1 and pFP11 and their ability to propagate in linear mode with artificially attached telomeres

Many Streptomyces species harbor circular plasmids (8 to 31 kb) as well as linear plasmids (12 to 1,700 kb). We report the characterization of two newly detected circular plasmids, pFP11 (35,139 bp) and pFP1 (39,360 bp). As on linear plasmids, their replication loci comprise repA genes and adjacent iterons, to which RepA proteins bind specifically in vitro. Plasmids containing the minimal iterons plus the repA locus of pFP11 were inherited extremely unstably; par and additional loci were required for stable inheritance. Surprisingly, plasmids containing replication loci from pFP11 or Streptomyces circular plasmid SCP2 but not from pFP1, SLP1, or pIJ101 propagated in a stable linear mode when the telomeres of a linear plasmid were attached. These results indicate bidirectional replication for pFP11 and SCP2. Both pFP11 and pFP1 contain, for plasmid transfer, a major functional traB gene (encoding a DNA translocase typical for Streptomyces plasmids) as well as, surprisingly, a putative traA gene (encoding a DNA nickase, characteristic of single-stranded DNA transfer of gram-negative plasmids), but this did not appear to be functional, at least in isolation.     

可诱导的稳定表达Spata3细胞系的建立及特征

spata3是一个在睾丸中特异性表达的基因,可能与精子发生或生精细胞凋亡相关.为了进一步研究Spata3的功能,将spata3克隆入经修饰的pcDNA5/FRT/TO表达载体,应用Flp-InTMT-RExTM-293 细胞系作为拗飨赴? 成功地构建了可被四环素或 Doxycline 诱导的稳定表达 Flp-InTMT-RExTM-sptat3 的细胞系.该细胞系在spata3基因 的3'端有2×FLAG tag和2×Histag,在缺乏可利用的spata3或其抗体的情况下,也能够很容易地应用商品化的FLAG抗体检测到spata3全长蛋白的表达.这种可诱导的稳定表达Flp-InTMT-Rex TM-spata3 的细胞系的建立,不仅有利于spata3的分析鉴定和功能研究,而且对于其他蛋白质的分离纯化和功能研究也有很好的借鉴作用.     

Cloning and characterization of TsMT3, a type 3 metallothionein gene from salt cress (Thellungiella salsuginea).

A full-length type 3 plant metallothionein cDNA was isolated from 200 mM NaCl stressed shoots of the salt cress (Thellungiella salsuginea). The 447 bp TsMT3 cDNA sequence has a 207 bp open reading frame (ORF) and encodes a deduced 69 residue peptide of molecular weight 7.52 kDa. Southern blot analysis indicates that, there is only one copy of TsMT3 in the T. salsuginea genome. The accumulation of TsMT3 mRNA is enhanced by the stress imposed by PEG6000, 200 mM NaCl, 50 microM ABA, 4 degrees C, 40 microM CuSO(4) or 25 microM CdCl2. The expression vector pET28-TsMT3 was heterologously expressed in Escherichia coli to define the contribution of TsMT3 to heavy metal tolerance. In the presence of 2 mM CuSO4, 0.3 mM Pb(NO3)2 or 0.4 mM CdCl2, TsMT3 expressing cells exhibited enhanced metal tolerance and accumulated more metal than the controls. We believe that TsMT3 is probably involved in the processes of metal homeostasis, tolerance, and reactive oxygen species (ROS) scavenging.     

Isolation and characterization of nine microsatellite loci for the takin (<Emphasis Type="Italic">Budorcas taxicolor</Emphasis>)

We report on the isolation and characterization of nine microsatellite markers in the takin (Budorcas taxicolor) from genomic DNA-enriched libraries. Twenty-eight microsatellites were screened from the libraries, and nine of the screened microsatellites were polymorphic. The number of observed alleles for each locus in 28 individuals ranged from two to seven, and the expected and observed heterozygosity was 0.105–0.758 and 0.071–0.821, respectively. Four loci (TK01, TK02, TK04 and TK08) of nine deviated from Hardy-Weinberg expectation and no significant linkage association was found among all these loci. These microsatellite markers provide useful tool for population genetic studies of the takin.     

Natural inhibitors of DNA topoisomerase I with cytotoxicities

DNA Topoisomerase I can cause DNA breaks and play a key role during cell proliferation and differentiation. It is an important target for anticancer agents. While screening for anticancer compounds, seven natural compounds, 1-7, showed potent cytotoxicities against a panel of ten cancer cell lines. Moreover, an inhibition assay demonstrated that they are also DNA topoisomerase I inhibitors, in which inhibitors 1-5 are new ones.     

Practical application of different enzymes immobilized on sepabeads

The immobilization of an endoglucanase, benzoylformate decarboxylase (BFD) from Pseudomonas putida, as well as of lipase B from Candida antarctica (CALB) onto the carrier supports Sepabeads EC-EP, Sepabeads EC-EA, and Sepabeads EC-BU was accomplished. It is shown that via these immobilized biocatalysts the synthesis of both fine and bulk chemicals is possible. This is illustrated by the syntheses of polyglycerol esters and (S)-hydroxy phenyl propanone. The benefit of immobilization is illustrated by repetitive use in a bubble column reactor as well as in a stirred tank reactor. High stability of two biocatalysts was achieved and reusability up to eight times was demonstrated. The comparison of CALB immobilized on Sepabeads EC-EP to Novozym 435 shows similar activity. Dedicated to Prof. Dr. Christian Wandrey on the occasion of his 65th birthday.