中国鸭茅主栽品种DNA指纹图谱构建

利用SSR标记和SCoT标记构建了我国主栽的21个鸭茅品种的DNA指纹图谱。从180对SSR引物和80个SCoT引物中,筛选出多态性高、谱带清晰的SSR引物和SCoT引物各24个。24对SSR引物在供试材料中共检测到186个条带,其中多态性条带为175个,品种特异条带6个,平均多态性比率94.03%,多态性信息量均值0.845,Shannon指数变幅0.4479~0.6549,基因多样性指数变幅0.2946~0.4633,可鉴别的品种数2~21个;利用24个SCoT引物在供试材料中共检测到321个条带,其中多态性条带为249个,品种特异条带6个,平均多态性比率76.33%,多态性信息量均值0.907,Shannon指数变幅0.2588~0.6329,基因多样性指数变幅0.1695~0.4451,可鉴别的品种数1~21个;5对SSR引物和5个SCoT引物在10个品种上具有唯一特征谱带,最终综合各项指标筛选出5个引物(A01E14、A01K14、B03E14、D02K13和SCoT23)上的37个条带用于鸭茅品种DNA指纹图谱构建,数据库中每个品种均具有唯一DNA指纹编码,构建的DNA指纹数据可用于鸭茅品种真伪鉴定,为品种权保护提供了科学依据。     

Leaf surface factors of transgenic Bt cotton associated with the feeding behaviors of cotton aphids: A case study on non-target effects

The present paper reports case study results of the risk assessment of transgenic Bt cotton on a non-target pest, cotton aphid, Aphis gossypii. Several types of techniques, i.e., electrical penetration graph (EPG), light and electron microscopy, bioassays and chemical analysis, were applied to investigate physical and chemical leaf factors of 2 transgenic Bt cotton lines (GK12 and GK19) and their pa-rental non-Bt cotton line (Simian3) associated with searching and feeding behaviors of cotton aphids on leaves or leaf extracts of cotton plants. EPG results showed that there were some differences among behaviors of cotton aphids on 2 Bt cotton and 1 non-Bt cotton lines. Cotton aphids performed similarly to leaf surface extracts from 3 cotton lines; and leaf surface chemicals, mainly volatiles and waxes, were almost identical in the components and concentrations among the cotton lines. However, three cotton lines were quite different from each other in the densities of certain kinds of covering trichomes. Therefore, the relationships between the physical characteristics and the searching behaviors of cotton aphids on the three cotton lines were constructed as the regression equations. Glandular trichomes and covering trichomes with 5 branches influenced the cotton aphids' searching behaviors effectively; and other trichomes with other branches affected aphids in varying ways. These results demonstrated that leaf surface physical factors of transgenic Bt cotton lines different from their parental non-Bt line could affect the penetration behaviors of non-target cotton aphids. Cotton aphids penetrate and feed more easily on two Bt cotton lines than on the non-Bt cotton line.     

Vector systems allowing efficient autonomous or integrative gene cloning in Micromonospora sp. strain 40027

Vector systems allowing autonomous or site-specific integrative gene cloning were developed for Micromonospora sp. strain 40027, a producer of the antibiotic fortimicin A. The autonomous system depends on the discovery of a low-copy-number, self-transmissible covalently closed circular plasmid, pJTU112 (ca. 14.1 kb), which was shown to be present in the progenitor strain in both integrated and autonomous states. The copy numbers of both wild-type pJTU112 and three derivatives of it can be amplified at least sixfold by addition of streptomycin to the culture medium. The integrative system was developed by the use of a pBR322-derived Escherichia coli plasmid vector, pSET152, mediated by the attP site of the Streptomyces phage PhiC31. Both vectors can be transferred by conjugation from E. coli into Micromonospora sp. strain 40027. The heterologous cloning and expression of the dnd gene cluster originating from Streptomyces lividans 1326 into Micromonospora sp. strain 40027 demonstrated the use of the two systems.     

Change of Genetic Architecture in Response to Sex

A traditional view is that sexual reproduction increases the potential for phenotypic evolution by expanding the range of genetic variation upon which natural selection can act. However, when nonadditive genetic effects and genetic disequilibria underlie a genetic system, genetic slippage (a change in the mean genotypic value contrary to that promoted by selection) in response to sex may occur. Additionally, depending on whether natural selection is predominantly stabilizing or disruptive, recombination may either enhance or reduce the level of expressed genetic variance. Thus, the role of sexual reproduction in the dynamics of phenotypic evolution depends heavily upon the nature of natural selection and the genetic system of the study population. In the present study, on a permanent lake Daphnia pulicaria population, sexual reproduction resulted in significant genetic slippage and a significant increase in expressed genetic variance for several traits. These observations provide evidence for substantial genetic disequilibria and nonadditive genetic effects underlying the genetic system of the study population. From these results, the fitness function of the previous clonal selection phase is inferred to be directional and/or stabilizing. The data are also used to infer the effects of natural selection on the mean and the genetic variance of the population.     

Hepatoprotective effect of Herpetospermum caudigerum Wall. on carbon tetrachloride‐induced hepatic fibrosis in rats

Tibetan medicine Herpetospermum caudigerum Wall. (HCW) has long been employed to treat hepatitis, inflammatory diseases and jaundice according to the records of “The Four Medical Tantras” in China. This study was investigated to explore the protective effects of HCW on hepatic fibrosis and the possible mechanism in a rat model. Hepatic fibrosis was established by intragastric administration of 3 ml/kg carbon tetrachloride (CCl₄) twice a week for 6 weeks. CCl₄‐treated rats were received HCW (1 and 3 g/kg/d) and silymarin (0.1 g/kg/d) from 3 to 6 weeks. The results showed that HCW could significantly decrease the levels of AST, ALT, HA, LN, PCIII, Col IV, TNF‐α, IL‐1β and IL‐6. Moreover, HCW could effectively inhibit collagen deposition and reduce the pathological damage. Analysis experiments finally exhibited that HCW was able to markedly inhibit hepatic fibrosis by modulating the expressions of NF‐κB p65, IκBα, Samd3 and TGF‐β1 proteins. Therefore, our results suggest that HCW has hepatoprotective activity against CCl₄‐induced hepatic fibrosis in rats by regulating the inflammatory responses.     

High throughput SNP genotyping with two mini-sequencing assays

Single nucleotide polymorphisms (SNPs) are veryimportant markers that can be used in many areas such asevolutionary genetics [1], disease-susceptibility genes[2,3], personalized medicine and forensics. Only about20% of human polymorphisms are length polymorphisms,whereas about 80% of human polymorphisms areSNPs. Kruglyak et al. [4] reported that there were about11,000,000 SNPs in the world population. There are many kinds of SNP genotyping technology[5,6]: some are only suitable to low …     

基于化学遗传学筛选产萘醌类化合物内生放线菌

【目的】为探究含具有抗肿瘤活性的美登素的滑桃(Trewia nudiflora)种子中内生放线菌的多样性,以及从内生放线菌中寻找萘醌类化合物产生菌。【方法】利用放线菌富集筛选培养基对经消毒处理的滑桃种子进行内生菌分离,根据菌落形态及16S rRNA基因序列分析进行菌种的分类鉴定。通过对所分离到的内生放线菌拮抗模式病原细菌(金黄色葡萄球菌、铜绿假单胞菌)、作物病原真菌(小麦赤霉菌、水稻纹枯病致病菌等)活性检测,以及萘醌类化合物合成关键基因为探针定向筛选萘醌类化合物产生菌。【结果】从分离到的100余株滑桃种子内生菌中鉴定出66株以链霉菌为主的放线菌,发现Streptomyces sp.HTZ27菌株含有目标基因,经固体发酵、化合物分离纯化、鉴定后,发现该菌发酵产物中有呋喃萘醌I,得率接近5 mg/L。【意义】本研究采用的化学遗传学方法可有效提高筛选目标化合物产生菌的效率,所筛选到FNQ I产生菌为深入研究呋喃萘醌类化合物生物合成与调控、抗肿瘤分子机理以及产业化应用等创建了有利条件。     

Diterpenoids from Wedelia prostrata and Their Derivatives and Cytotoxic Activities

One new ent‐kaurane diterpenoid, 11β,16α‐dihydroxy‐ent‐kauran‐19‐oic acid ( 1 ), together with eight known analogues 2 – 9 were isolated from the aerial parts of Wedelia prostrata. One of the acidic diterpenoids, kaurenoic acid ( 3 ), was converted to seven derivatives, 10 – 16 . All compounds were evaluated for their cytotoxic activity in vitro against human leukemia (K562), liver (HepG‐2), and stomach (SGC‐7901) cancer cell lines. Only four kaurenoic acid derivatives, 13 – 16 , with 15‐keto and substitutions at C(19) position, exhibited notable cytotoxic activities on these tumor cell lines with IC₅₀ value ranging from 0.05 to 3.71 μm . Compounds 10 – 12 , with oxime on C(15) showed moderate inhibitory effects and compounds 1 – 9 showed no cytotoxicities on them. Structure–activity relationships were also discussed based on the experimental data obtained. The known derivative, 15‐oxokaurenoic acid 4‐piperdin‐1‐ylbutyl ester ( 17 ), induced typical apoptotic cell death in colon SW480 cells upon evaluation of the apoptosis‐inducing activity by flow‐cytometric analysis.     

Probing and Engineering the Fatty Acyl Substrate Selectivity of Starter Condensation Domains of Nonribosomal Peptide Synthetases in Lipopeptide Biosynthesis

Lipopeptides are produced by nonribosomal peptide synthetases (NRPSs) and contain diverse fatty acyl moieties that are major determinants of antibiotic potency. The lipid chains are incorporated into peptidyl backbones via lipoinitiation, a process comprising free fatty acid activation and the subsequent starter condensation domain (C1)‐catalyzed conjugation of fatty acyl moieties onto the aminoacyl substrates. Thus, a thorough understanding of lipoinitiation biocatalysts would significantly expand their potential to produce novel antibiotics. Here, biochemical assays, in silico analysis, and mutagenesis studies are used to ultimately identify the specific amino acid residues that control the fatty acyl substrate selectivity of C1 in lipopeptide A54145. In silico docking study has identified four candidate amino acids, and subsequent in vitro assays confirmed their functional contribution to the channel that controls substrate selectivity. Two engineered variants with single point mutations in C1 are found to alter the substrate selectivity toward nonnatural fatty acyl substrates. The detailed mechanistic insights into the catalytic contribution of C1 obtained from the present study will facilitate future NPRS biocatalyst efforts