Reductive transformation of parathion and methyl parathion by Bacillus sp.

Based on the results of phenotypic features, phylogenetic similarity of 16S rRNA gene sequences and BIOLOG test, a soil bacterium was identified as Bacillus sp. DM-1. Using either growing cells or a cell-free extract, it transformed parathion and methyl parathion to amino derivatives by reducing the nitro group. Pesticide transformation by a cell-free extract was specifically inhibited by three nitroreductase inhibitors, indicating the presence of nitroreductase activity. The nitroreductase activity was NAD(P)H-dependent, O₂-insensitive, and exhibited the substrate specificity for parathion and methyl parathion. Reductive transformation significantly decreased the toxicity of pesticides.     

小菜蛾羧酸酯酶基因的克隆及其序列分析

利用CODEHOP设计简并引物,通过反转录多聚酶链式反应(RTPCR)克隆小菜蛾Plutellaxylostella抗性种群中抗性相关的羧酸酯酶基因,随机挑取测序5个阳性克隆进行测序,测序结果经过blastx比较,发现所获得的大约420bp的基因片断均为羧酸酯酶基因,与双翅目昆虫蚊子的氨基酸序列同源性达85%以上 。     

Effects of amylose/amylopectin ratio on starch-based superabsorbent polymers

Biodegradable superabsorbent polymers (SAPs) were prepared by grafting acrylamide onto starches then crosslinking with N,N′-methylene-bisacrylamide. This work focused on the effects of the amylose/amylopectin ratio of starches from the same source (corn) on the grafting reactions and performance of the resultant starch-based SAPs. To characterise each SAP, the acrylamide groups grafted onto the starch were detected by FTIR; grafting ratio and grafting efficiency were evaluated by a gravimetric method; and graft position and the length of the grafted segment were investigated by NMR. The relationships between the microstructures of the starches, and the graft reactions and performance of the SAPs were studied based on the amylose content in the starches. It was found that under the same reaction conditions, the grafting ratio and efficiency increased with increasing amylose content, which corresponds with water absorption ratio. NMR results indicated that the acrylamide group mainly grafted onto C6, and that the length of the grafted segment decreased with increasing amylopectin content in general, and in particular for waxy starch. The high molecular weight and branched structure of amylopectin reduced the mobility of the polymer chains and increased viscosity, which could explain the graft reactions and performance of the starch-based SAPs.     

Isolation and Characterization of Two Novel Antibacterial Cyclic Hexapeptides from Streptomyces alboflavus 313

Two novel cyclic hexapeptides, designated NW-G08 (1) and NW-G09 (2), were isolated from the fermentation broth of Streptomyces alboflavus 313. Their structures were elucidated on the basis of extensive spectroscopic analysis, MS experiments, and chemical analysis. Their antibacterial activities against several strains of bacteria were evaluated by micro-broth dilution method. NW-G08 (1) and NW-G09 (2) were highly antibacterial against Gram-positive but not active against Gram-negative bactaria. The minimum inhibitory concentrations (MICs) of 1 against Bacillus cereus, Bacillus subtilis, and Staphylococcus aureus were 6.25, 6.25, and 1.56?μg/ml, respectively. It is worth noting that 1 and 2 exhibited much higher activities against methicillin-resistant Staphylococcus aureus (MRSA) than ampicillin, which implies that they might be potential candidates for the development of novel drugs against resistant pathogenic bacteria.     

High‐throughput multiplex cpDNA resequencing clarifies the genetic diversity and genetic relationships among Brassica napus,Brassica rapa and Brassica oleracea

Brassica napus (rapeseed) is a recent allotetraploid plant and the second most important oilseed crop worldwide. The origin of B. napus and the genetic relationships with its diploid ancestor species remain largely unresolved. Here, chloroplast DNA (cpDNA) from 488 B. napus accessions of global origin, 139 B. rapa accessions and 49 B. oleracea accessions were populationally resequenced using Illumina Solexa sequencing technologies. The intraspecific cpDNA variants and their allelic frequencies were called genomewide and further validated via EcoTILLING analyses of the rpo region. The cpDNA of the current global B. napus population comprises more than 400 variants (SNPs and short InDels) and maintains one predominant haplotype (Bncp1). Whole‐genome resequencing of the cpDNA of Bncp1 haplotype eliminated its direct inheritance from any accession of the B. rapa or B. oleracea species. The distribution of the polymorphism information content (PIC) values for each variant demonstrated that B. napus has much lower cpDNA diversity than B. rapa; however, a vast majority of the wild and cultivated B. oleracea specimens appeared to share one same distinct cpDNA haplotype, in contrast to its wild C‐genome relatives. This finding suggests that the cpDNA of the three Brassica species is well differentiated. The predominant B. napus cpDNA haplotype may have originated from uninvestigated relatives or from interactions between cpDNA mutations and natural/artificial selection during speciation and evolution. These exhaustive data on variation in cpDNA would provide fundamental data for research on cpDNA and chloroplasts.     

菘蓝多倍体育种的研究

本文报道药用植物菘蓝(Isatis indigotica Foft.)同源四倍体的诱发、鉴定、选育的研究。用0.05-0.5％浓度的秋水仙碱水溶液处理萌发的种子,或用0.05-0.3％浓度的此溶液处理幼苗的生长点,均可以获得四倍体植株。最适宜的处理时间为6-12小时。除用直接的细胞学技术鉴定多倍体植株外,一些重要的间接鉴定特征,如叶表皮保卫细胞中叶绿体数,花粉沟数可作为鉴定本种多倍体植株的可靠指标。比较了四倍体植株和二倍体亲本的生物学特性。经过数代选育,获得了性状稳定、繁殖力正常、根与叶中活性成分均有较大幅度提高、生产性能良好的品系。     

Improvements of the Surgical Technique on the Established Mouse Model of Orthotopic Single Lung Transplantation

Background

A wide range of knockout and transgenic murine models for the study of nonimmune and immune mechanisms in lung transplants are available nowadays, but the microsurgical techniques are difficult to learn. We describe methods to simplify techniques and facilitate learning.

Methods

Traditional procedures were implemented to perform lung transplants in 30 cases (group 1). Improved techniques which included cuff without tail, broadening of the cuff diameter for bronchus, establishment of one tunnel between three structures, innovative technology of the vascular anastomosis and placement of the chest tube post-operation were used to perform lung transplants in 30 cases (group 2).

Results

The improved techniques considerably shorten operative times (96.75±6.16 min and 85.32±6.98 min in groups 1 and 2, respectively). The survival rates in the recipient animals were 86.7% and 96.7% in groups 1 and 2, respectively. Chest X-rays and macroscopic changes of transplanted recipients showed that grafts were well inflated on postoperative day 30. There was no significant difference of the arterial oxygen tension (PaO₂) between two groups (115.9±7.11 mm Hg and 116.3±6.87 mm Hg in groups 1 and 2, respectively). Histologically, no lung injury was seen in grafts.

Conclusions

We described the modified procedures of orthotopic left lung transplants in mice, which could shorten operative time and increase survival rate.     

Gliadin T cell epitope selection by tissue transglutaminase in celiac disease. Role of enzyme specificity and pH influence on the transamidation versus deamidation process

Tissue transglutaminase (TG2) can modify proteins by transamidation or deamidation of specific glutamine residues. TG2 has a major role in the pathogenesis of celiac disease as it is both the target of disease-specific autoantibodies and generates deamidated gliadin peptides that are recognized by CD4(+), DQ2-restricted T cells from the celiac lesions. Capillary electrophoresis with fluorescence-labeled gliadin peptides was used to separate and quantify deamidated and transamidated products. In a competition assay, the affinity of TG2 to a set of overlapping gamma-gliadin peptides was measured and compared with their recognition by celiac lesion T cells. Peptides differed considerably in their competition efficiency. Those peptides recognized by intestinal T cell lines showed marked competition indicating them as excellent substrates for TG2. The enzyme fine specificity of TG2 was characterized by synthetic peptide libraries and mass spectrometry. Residues in positions -1, +1, +2, and +3 relative to the targeted glutamine residue influenced the enzyme activity, and proline in position +2 had a particularly positive effect. The characterized sequence specificity of TG2 explained the variation between peptides as TG2 substrates indicating that the enzyme is involved in the selection of gluten T cell epitopes. The enzyme is mainly localized extracellularly in the small intestine where primary amines as substrates for the competing transamidation reaction are present. The deamidation could possibly take place in this compartment as an excess of primary amines did not completely inhibit deamidation of gluten peptides at pH 7.3. However, lowering of the pH decreased the reaction rate of the TG2-catalyzed transamidation, whereas the rate of the deamidation reaction was considerably increased. This suggests that the deamidation of gluten peptides by TG2 more likely takes place in slightly acidic environments.     

A New GA-Insensitive Semidwarf Mutant of Rice (Oryza sativa L.) with a Missense Mutation in the SDG Gene

A semidwarf line of Indica rice, Xinguiai, was derived from the progeny of a cross between the double dwarf mutant Xinguiaishuangai and the wild-type variety Nanjing 6. The semidwarf phenotype was controlled by the semidwarf gene, sdg. The second sheath and shoot elongation responses of the dwarf mutant to exogenous gibberellin (GA₃) showed that sdg was insensitive to gibberellin (GA), and its endogenous GAs content was higher than that in wild-type cultivars. The SDG gene was cloned by a map-based cloning method and sequencing analysis revealed that the coding region of sdg had a single nucleotide substitution resulting in a single amino acid change from alanine to threonine. A cleaved amplified polymorphic sequence marker was designed according to sequences from mutant and wild-type materials. This sequence marker could be used to distinguish wild types and mutants, and thus, could be used for molecular marker-assisted selection. The dwarf phenotype of the sdg mutant was restored to a normal phenotype by introducing the wild-type SDG gene. Rice transformation experiments and GUS staining demonstrated that the SDG gene was predominantly expressed in vegetative organs.