醉马草内生菌的分离、鉴定及杀虫效果

【目的】探明醉马草内生菌的种类,筛选对农作物虫害有毒杀作用的菌株。【方法】采用研磨法从健康醉马草植物的根、茎、叶和种子中进行菌种分离;通过对其形态、培养特征、生理生化及其他生物学特性的研究;16SrDNA及ITS序列的系统发育学分析进行鉴定;用玻片浸渍法和喷雾法筛选产杀虫活性物质菌株。【结果】获得细菌89株,分别属于枯草芽孢杆菌属(Bacillus)、链霉菌属(Streptomyces)、棒状杆菌属(Corynebacterium)、叶杆菌属(Phyllobacterium)、鞘脂单胞菌属(Sphingomonnas)、类芽孢杆菌(Paenibacillus)、假单胞菌属(Pseudomonas)和不动杆菌属(Acinetobacter)8个属;真菌2株,分别属于麦角菌属(Claviceps)和毛壳菌属(Chaetomium)。经初筛及复筛,内生菌娄彻氏链霉菌Streptomyces rochei(GA)和黑麦麦角菌Claviceps purpurea(PF-2)发酵液粗提物对棉蚜虫(Aphis gossypii)致死率达85%以上。【结论】醉马草内生菌株PF-2和GA的粗提代谢物对棉蚜虫有明显的毒杀作用,为开发新的生物源农药提供了生物源物质。     

Some dicopper complexes of benzimidazole-containing ligands.

Dicopper complexes of the following benzimidazole-containing ligands have been studied as possible models for the active site of hemocyanin: EDTB (N,N,N',N'-tetrakis-(2-benzimidazolylmethyl)-1,2-ethanediamine), EGTB (1,1,10,10-tetrakis-(2-benzimidazolylmethyl)-1,10-diaza-4,7- dioxadecane), and MEGTB (1,1,10,10-tetrakis-(1-methylbenzimidazol-2-y lmethyl)-1,10-diaza-4,7-dioxadecane). The initial oxygenation product of Cu2(EDTB)(ClO4)2 in Me2SO gives optical absorption maxima at 315 nm (epsilon = 3750 M-1 cm-1) and 690 nm (epsilon = 100 M-1 cm-1). The fluorescence emission intensities of Cu2(EDTB)(ClO4)2 at 400 and 700 nm (excitation at 350 nm) decreases rapidly on exposure to air. This suggests oxidation of Cu2(I) to Cu2(II). The x-ray absorption edge spectra suggest that both coppers in the oxygenation product, analyzed as Cu2(EDTB)(ClO4)2(O).3H2O, are Cu(II). From spectrophotometric titration of Cu2(MEGTB)Cl4 with azide, formation constant of the Cu2(MEGTB)N3Cl3 complex has been obtained. Data from cyclic voltammetry experiments suggest that in the presence of azide, Cu(II)(N3)Cu(II) species is present.     

New criteria on global exponential stability of bam neural networks with distributed delays and reaction-diffusion terms

This paper presents new theoretical results on global exponential stability of bi-directional associative memory neural networks with distributed delays and reaction-diffusion terms based on the inequality technique, Lyapunov functional, and analysis technique. The results remove the usual assumption that the activation functions are of monotonous or differential character. Exponential converging velocity index is estimated, which depends on the delay kernel functions and system parameters. Finally, two numerical examples are given to show the validity and feasibility of our results.     

RNAi knockdown of Oryza sativa root meander curling gene led to altered root development and coiling which were mediated by jasmonic acid signalling in rice

Jasmonic acid (JA) is a well-known defence hormone, but its biological function and mechanism in rice root development are less understood. Here, we describe a JA-induced putative receptor-like protein (OsRLK, AAL87185) functioning in root development in rice. RNA in situ hybridization revealed that the gene was expressed largely in roots, and a fusion protein showed its localization on the plasma membrane. The primary roots in RNAi transgenic rice plants meandered and curled more easily than wild-type (WT) roots under JA treatment. Thus, this gene was renamed Oryza sativa root meander curling (OsRMC). The transgenic primary roots were shorter, the number of adventitious roots increased and the number of lateral roots decreased as compared to the WT. As well, the second sheath was reduced in length. Growth of both primary roots and second sheaths was sensitive to JA treatment. No significant change of JA level appeared in the roots between the transgenic rice line and WT. Expression of RSOsPR10, involved in the JA signalling pathway, was induced in transgenic rice. Western blotting revealed OsRMC induced by JA. Our results suggest that OsRMC of the DUF26 subfamily involved in JA signal transduction mediates root development and negatively regulates root curling in rice.     

Regeneration of doubled haploid plants by androgenesis of cucumber (<Emphasis Type="Italic">Cucumis sativus </Emphasis>L.)

Six experiments (including pretreatment, embryonic callus induction media, preculture conditions, embryo induction media, embryo germination media, and genotypic effects) were conducted to develop an efficient cucumber (Cucumis sativus L., 2n = 2x = 14) anther culture protocol. Pretreatment and embryo induction were key factors for successful anther culture. Suitable temperature stress depended on the ecotype, i.e., cucumbers from cold areas responded well to cold shock whereas those from temperate areas responded well to heat treatment. The best medium for embryonic callus induction was MS medium supplemented with 4.44 μM BA, 2.26 μM 2, 4-D, 4.64 μM KIN, 3% sucrose and 0.8% agar. For embryo induction, MS medium supplemented with 0.54 μM NAA, 13.32 μM BA, 3% sucrose and 0.8% agar was optimal, and for embryo germination MS medium containing 2.22 μM BA, 6% sucrose and 1.2% agar was best. Using this protocol, we produced callus from 16 genotypes and regenerated plants from three of 20 evaluated. Three embryos per anther and 42 DH per 45 anthers (93% success) were obtained for cv. Ningjia No. 1, which was an improved result over a previous report. The origin of regenerants from microspores was determined by cytological, morphological and AFLP analyses.     

ent-Abietane diterpenoids from Isodon rubescens var. rubescens

ent-Abietane diterpenoids, hebeiabinins A-F (1-5), together with seven known diterpenoids were isolated from leaves of Isodon rubescens var. rubescens. The structures of 1-5 were established on the basis of spectroscopic analyses, including application of 2D NMR spectroscopic techniques. The diterpenoids isolated were evaluated for the cytotoxicity against A549, HT-29, and K562 tumor cells. Compound 5 was the most active with IC(50) value of 0.91 microM against A549 cells.     

Secondary metabolites from Commiphora opobalsamum and their antiproliferative effect on human prostate cancer cells

A cycloartane-type triterpenoid (1), an aliphatic alcohol glycoside (2), an eudesmane-type sesquiterpenoid (3), and a guaiane-type sesquiterpenoid (4) were isolated from the resinous exudates of Commiphora opobalsamum along with six known sesquiterpenoids (5-10). Their structures were established by extensive analysis of their 1D and 2D NMR spectroscopic data and chemical methods. The isolated compounds 1-3 and 5-9 were tested against human prostate cancer cell PC 3 and LNCaP. Among them, 1 and 2 showed moderate antiproliferative effects on human prostate cancer cell lines with IC50 values ranging from 5.7 to 23.6 microM; they were also able to inhibit the expression of androgen receptor (AR) in LNCaP cells. The six sesquiterpenoids were inactive in the bioassays.     

Cytological diploidization and rapid genome changes of the newly synthesized allotetraploids <Emphasis Type="Italic">Cucumis × hytivus</Emphasis>

We used a newly synthesized allotetraploid between C. sativus (2n = 2x = 14, n gametic chromosome number, x haploid chromosome number) and C. hystrix (2n = 2x = 24) to study the genomic events in its early generations. Results from cytological characterization of the F₁ and the allotetraploid progenies showed that the rate of bivalents in meiotic metaphase I of the F₁ was greatly improved by chromosome doubling, and further improved during the selfing process of allopolyploid resulting into relatively diploid-like meiosis. Extensive genomic changes were detected by amplified fragment length polymorphism analysis. The changes mainly involved loss of parental restriction fragments and gaining of novel fragments. The total detectable changes were from 11.1 to 32.1%, and the frequency of losing parental fragments was much higher than that of gaining novel fragments. Some of the changes were initiated as early as in the F₁ hybrid, whereas others occurred after chromosome doubling (polyploid formation). No significant differences were detected in the reciprocal F₁ hybrids and S₀ generations. But the data showed that the frequency of sequence losing in C. sativus was about two times higher than in the C. hystrix. Our results demonstrated that the sequence elimination was the major event of genomic changes, and it might provide the physical basis for the diploid-like meiotic behavior in the diploidization of the newly formed allopolyploids. Moreover, the results suggest that the sequence elimination was not caused by cytoplasmic factors, and might relate to genomic recombination and to the numbers of parental chromosome.     

Effects of venom/calyx fluid from the endoparasitic wasp Cotesia plutellae on the hemocytes of its host Plutella xylostella in vitro

Crude venom and calyx fluid from Cotesia plutellae (Hymenoptera Braconidae) were assayed for biological activity toward hemocytes of Plutella xylostella (Lepidoptera Plutellidae). Venom from C. plutellae displayed high activity toward the spreading of plasmatocytes of P. xylostella early in the incubation period, and the inhibition was more severe as the concentration of venom increased. However, most inhibited hemocytes spread normally after being incubated for 4h. No effects were found toward granular cells from the host. Additionally, the venom from C. plutellae had some lethal effects on hemocytes of P. xylostella at high concentrations. In contrast, when incubated with different concentrations of calyx fluid, the spreading of some hemocytes was inhibited, some began to disintegrate, and some were badly damaged with only the nucleus left. After 4h, the majority of hemocytes died. The same results were observed when hemocytes were incubated in calyx fluid together with venom. These results show that calyx fluid from C. plutellae may play a major role in the suppression of the host immune system, whereas venom from C. plutellae has a limited effect on hemocytes and probably synergizes the effect of calyx fluid or polydnavirus.