Biosynthesis of Cercosporin

¹³C NMR spectra were measured for 19 pyrethroids and their related compounds including allethrin, tetramethrin, resmethrin, furamethrin, phenothrin and permethrin. Complete assignment of chemical shifts was accomplished by relative spectral pattern, single-frequency off-resonance decoupling, benzene substituent effects, proton selective decoupling and use of shift reagents. The use of shift reagent was found to be especially efficient for assignment of ¹³C resonances. In the case of allethrin, the splittings of some resonance peaks were observed originating from diastereomerism.     

大孔树脂分离纯化“黑金刚”紫马铃薯花青苷工艺研究

以紫色马铃薯"黑金刚"花青苷为原料,采用D101、HDP100A、HDP450A、NK-9、AB-8五种大孔吸附树脂对花青苷的吸附与解析特性进行了比较研究,并在此基础上,采用最佳大孔树脂对花青苷纯化过程中的静态、动态吸附和解析附条件进行了优化研究。结果表明AB-8大孔树脂具有较好的吸附和解析能力,是纯化紫色马铃薯花青苷的最佳树脂,较优纯化条件为:上样液花青苷浓度为0.028mg.g-1,上样液pH=2,洗脱液乙醇浓度为50%,洗脱液pH=1,吸附流速为1mL.min-1,洗脱流速为1mL.min-1。经大孔树脂纯化后,色价值比纯化前提高了7.55倍。     

Effects of honeydew sugar composition on the longevity of Aphidius ervi

Feeding on sugar‐rich foods such as nectar and honeydew is important for survival of many adult parasitoids. Especially in agricultural systems, honeydew is often the most prevalent carbohydrate source. However, relative to plant nectar, honeydew may be relatively unsuitable, as a result of an unfavourable sugar composition or the presence of secondary plant compounds. We studied survival of the aphid parasitoid Aphidius ervi Haliday (Hymenoptera: Braconidae) on honeydew collected from various aphid species feeding on potato (Solanum tuberosum L., cv. Desiree) (Solanaceae), wheat (Triticum aestivum L., cv. Bobwhite) (Poaceae), or artificial diet, as well as the sugar composition of the different honeydews. Honeydews from the tested aphid species on potato, wheat, or artificial diet were found to be relatively suitable food sources for adult A. ervi, although not always as suitable as a 2 M sucrose solution. There were differences in honeydew sugar composition among the different aphid species on the various host plants. Multivariate statistics showed that the factor ‘aphid species’ had a significant influence on the sugar composition of the honeydew, explaining 27% of the variation in the potato system and 89% in the wheat system. When exploring the relationship between carbohydrate composition of the honeydews from aphids on potato and wheat plants, and their nutritional value for A. ervi, data revealed that differences in parasitoid longevity can to some extent be explained by carbohydrate composition. Furthermore, our results confirm that sucrose and its hexose components glucose and fructose are very suitable carbohydrate sources for hymenopteran parasitoids and show that parasitoid survival on an equimolar solution of the two monosaccharides glucose and fructose does not exceed performance on the disaccharide sucrose.     

Conformational and functional studies of gomesin analogues by CD, EPR and fluorescence spectroscopies

The aim of this work was to examine the bioactivity and the conformational behavior of some gomesin (Gm) analogues in different environments that mimic the biological membrane/water interface. Thus, manual peptide synthesis was performed by the solid-phase method, antimicrobial activity was evaluated by a liquid growth inhibition assay, and conformational studies were performed making use of several spectroscopic techniques: CD, fluorescence and EPR. [TOAC¹]-Gm; [TOAC¹, Ser^2,6,11,15]-Gm; [Trp⁷]-Gm; [Ser^2,6,11,15, Trp⁷]-Gm; [Trp⁹]-Gm; and [Ser^2,6,11,15, Trp⁹]-Gm were synthesized and tested. The results indicated that incorporation of TOAC or Trp caused no significant reduction of antimicrobial activity; the cyclic analogues presented a β-hairpin conformation similar to that of Gm. All analogues interacted with negatively charged SDS both above and below the detergent's critical micellar concentration (cmc). In contrast, while Gm and [TOAC¹]-Gm required higher LPC concentrations to bind to micelles of this zwitterionic detergent, the cyclic Trp derivatives and the linear derivatives did not seem to interact with this membrane-mimetic system. These data corroborate previous results that suggest that electrostatic interactions with the lipid bilayer of microorganisms play an important role in the mechanism of action of gomesin. Moreover, the results show that hydrophobic interactions also contribute to membrane binding of this antimicrobial peptide.     

甘薯根腐病菌侵染对甘薯内源激素水平的影响

甘薯根腐病病原菌[Fusarium solani(Mart.)Sacc.f.sp.batatas McClure,简称FSB]侵染及其培养液滤液处理高敏感性甘薯品种‘胜利百号’后,引起甘薯叶片、茎尖和根部组织内源ABA含量大幅升高。其中在根部出现最早,但茎尖中积累浓度最高。侵染后甘薯叶片、茎尖和根部组织内源GA1/3含量显著低于对照。甘薯组培苗经FSB培养滤液处理9h后,ABA含量显著上升,处理15h,ABA含量呈下降趋势,而GA1/3含量在101和102稀释液处理15h(103稀释液处理12h)时出现显著上升。这些结果有助于解释甘薯根腐病株矮小不产生藤蔓,并在秋季大量现蕾开花的生理现象。     

Activity of phosphorylase in Solanum tuberosum during low temperature storage

Changes in the activity of phosphorylase were measured during storage of potatoes at + 2° when the sugar content rises rapidly and subsequently at + 10° when the accumulated sugar is converted mainly to starch. The observed changes were relatively small and could not be related to any of the components of the phosphorylase system, which was shown to be complex.     

Isolubimin: A possible precursor of lubimin in infected potato slices

Potato slices treated with spirovetiva-1(10),11-diene-2-one yield lubimin and rishitin within 24 hr. A vetispirane which has not been detected in fungally infected potatoes was also isolated. This compound, isolubimin, appears to be an intermediate in the conversion of the above spirovetivone to lubimin.     

Phosphofructokinase of Solanum tuberosum tuber

Potato tuber phosphofructokinase was purified 19·.6-fold by a combination of ethanol fractionation and DEAE-cellulose column chromatography. The enzyme was very unstable; its pH optimum was 8·0. K_m for fructose-6-phosphate, ATP and Mg²⁺ was 2·1 × 10^?4 M, 4·5 × 10^?5 M and 4·0 × 10^?4 M respectively. ITP, GTP, UTP and CTP can act as phosphate donors, but are less active than ATP. Inhibition of enzyme activity by high levels of ATP was reversed by increasing the concentration of fructose-6-phosphate; the affinity of enzyme for fructose-6-phosphate decreased with increasing concentration of ATP. 5′-AMP, 3′,5′-AMP, 3′-AMP, deoxy AMP, UMP, IMP, CMP, GMP, ADP, CDP, GDP and UDP did not reverse the inhibition of enzyme by ATP. ADP, phosphoenolpyruvate and citrate inhibited phosphofructokinase activity but Pi did not affect it. Phosphofructokinase was not reactivated reversibly by mild change of pH and addition of effectors.     

福建甘薯病毒病病原鉴定及主要病毒多样性

【背景】病毒病是甘薯的一种重要病害,给甘薯生产带来了严重的经济损失,而生产中甘薯病毒病病原种类复杂多样。【目的】明确福建甘薯病毒病种类、分布及流行,对主要病毒进行多样性分析。【方法】从福建主要甘薯种植区采集病毒病样品,利用PCR/RT-PCR的方法对采集的样品进行病原检测,获得病毒序列,利用MEGA 6.0构建系统进化树进行遗传分析。【结果】从福建7个甘薯产区鉴定12种甘薯病毒,包括9种RNA病毒:甘薯羽状斑驳病毒(Sweet potato feathery mottle virus,SPFMV)、甘薯褪绿矮化病毒(Sweet potato chlorotic stunt virus,SPCSV)、甘薯G病毒(Sweet potato virus G,SPVG)、甘薯C病毒(Sweet potato virus C,SPVC)、甘薯2号病毒(Sweet potato virus 2)、甘薯褪绿斑病毒(Sweet potato chlorotic fleck virus,SPCFV)、甘薯潜隐病毒(Sweet potato latent virus,SPLV)、甘薯轻型斑点病毒(Sweetpotatomildspeakingvirus,SPMSV)、黄瓜花叶病毒(Cucumber mosaic virus,CMV),3种DNA病毒:甘薯卷叶病毒(Sweet potato leaf curl virus,SPLCV),甘薯无症状1号病毒(Sweet potato symptomless virus 1,SPSMV-1),甘薯杆状DNA病毒B (SPBV-B)。SPFMV、SPCSV、SPVG和SPLCV检出率最高,分别为50.28%、41.90%、35.75%和24.58%,CMV检出率最低,为2.79%,未检测到甘薯C-6病毒(SweetpotatoC-6)和甘薯轻型斑驳病毒(Sweetpotatomild mottle virus,SPMMV)。福建甘薯主要以2-6种病毒复合侵染为主,单一侵染率占14.39%,2种以上复合侵染占85.61%。福建SPFMV分离物存在EA、O和RC3种株系,SPCSV分离物存在WA1种株系,未发现EA株系,甘薯卷叶病毒分属于2个不同的株系群。【结论】福建甘薯病毒种类多样,以复合侵染为主,且存在多种株系,遗传结构复杂。     

The potential of novel African isolates of Phthorimaea operculella granulovirus for the control of Tuta absoluta

Phthorimaea operculella granulovirus (PhopGV) is infectious for larvae of different Gelechiidae insect species, including Tuta absoluta and Phthorimaea operculella. As these are major economic pests in North and sub‐Saharan Africa as well as in the Mediterranean area, the development of locally suitable biocontrol agents is essential. We have studied five isolates of PhopGV from Tunisia (Tns16, Tu1.11 and Tu2.11), Kenya (Ken13) and Yemen (Ym14) for their biological activity and the sequence polymorphism of their granulin and ecdysteroid UDP‐glucosyltransferase (egt) genes and allocated the isolates to two different egt types. Infection experiments with neonate larvae of T. absoluta and P. operculella demonstrated their pathogenicity to both host species. The isolate PhopGV Tu1.11 was the most virulent one for T. absoluta but had a relatively low infectivity to two P. operculella populations originating from Italy and Tunisia.