Thermospray high performance liquid chromatographic/mass spectrometric analysis of some fusarium mycotoxins

Thermospray high performance liquid chromatography/mass spectrometry (TSP HPLC/MS) was used to analyze five Fusarium mycotoxins in porcine plasma and urine. Four cytotoxic trichothecene mycotoxins, T-2 toxin, HT-2 toxin, diacetoxyscirpenol (DAS), deoxynivalenol (DON), T2 tetraol, and the fungal estrogen zearalenone (F-2 toxin) were analyzed. The thermospray mass spectrum contained molecular weight information with few, if any, fragment signals. Detection limits ranging from 1 to 10 ng of mycotoxin injected onto the HPLC column were obtained using selected ion monitoring (SIM) HPLC/MS. Neither the plasma nor the urine matrix interfered with TSP HPLC/MS analysis of these mycotoxins and no sample derivatization was necessary for the analysis. The TSP HPLC/MS technique appears to be ideal for very sensitive analysis of mycotoxins in biological samples.     

Quinolizidine-Based Variations and Antifungal Activity of Eight Lupinus Species Grown under Greenhouse Conditions

Fusarium oxysporum is an aggressive phytopathogen that affects various plant species, resulting in extensive local and global economic losses. Therefore, the search for competent alternatives is a constant pursuit. Quinolizidine alkaloids (QA) are naturally occurring compounds with diverse biological activities. The structural diversity of quinolizidines is mainly contributed by species of the family Fabaceae, particularly the genus Lupinus. This quinolizidine-based chemo diversity can be explored to find antifungals and even mixtures to address concomitant effects on F. oxysporum. Thus, the antifungal activity of quinolizidine-rich extracts (QREs) from the leaves of eight greenhouse-propagated Lupinus species was evaluated to outline promising QA mixtures against F. oxysporum. Thirteen main compounds were identified and quantified using an external standard. Quantitative analysis revealed different contents per quinolizidine depending on the Lupinus plant, ranging from 0.003 to 32.8 mg/g fresh leaves. Bioautography showed that all extracts were active at the maximum concentration (5 µg/µL). They also exhibited >50% mycelium growth inhibition. All QREs were fungistatic except for the fungicidal QRE of L. polyphyllus Lindl. Angustifoline, matrine, 13α-hydroxylupanine, and 17-oxolupanine were ranked to act jointly against the phytopathogen. Our findings constitute reference information to better understand the antifungal activity of naturally afforded QA mixtures from these globally important plants.     

STUDIES ON CAUSES OF THE POCKMARKED DISEASE OF CHINESE ANGELICA

The present studies show that there is a biocommunity including 59 kinds of organisms in and around the focus of angelica pockmarked disease to form a soil food web. These results add new content to the relationship among food webmembersr~[1, 2]. The studies prove that 6 species of Fusarium are pathogenes, the wounds caused by underground insects and artificial factors are beneficial to pathogene infection, and invertebrates carrying pathogenes aggravate the disease. According to the tests, a disease control method is proposed and applied to 14, 000 mu in Gansu Province, and economic and social benefits have been obtained. The present studies are part of the state projects on technological development of agriculture, animal husbandry and fishery.     

Sesquiterpenoids from Fusarium sp., an Endophytic Fungus in Agriminia pilosa

Cultivation of the endophytic fungus isolated from the stems of Agriminia pilosa provided four new sesquiterpenoids, namely agripilols A–D ( 1 – 4 , resp.). Structures of these isolates were elucidated by NMR and MS data. The isolation of drimane‐ and cadinane‐type sesquiterpenoids from the genus of Fusarium is reported for the first time.     

高光谱数据处理算法的小麦赤霉病籽粒识别

赤霉病是小麦的一种主要病害,它会导致小麦减产甚至绝收,严重影响小麦种子质量,此外小麦受侵染分泌的真菌毒素危害人类身体健康。因此,小麦赤霉病籽粒的识别具有非常重要的意义。起初普遍采用色谱法和酶联免疫法进行赤霉病检测,这些方法设备昂贵、检测速度慢、准确性低。近年来,高光谱成像技术被广泛应用于农作物的识别与检测中,但是在小麦赤霉病检测的应用研究中,大多采用抽样检测的方法,图像采集完成后需要通过ENVI软件手动选取感兴趣区域。前期准备工作冗杂,而且容易发生漏检,漏检的小麦籽粒在存储运输过程中向周边籽粒快速侵染,难以保障小麦安全健康。鉴于此,利用高光谱成像系统结合机器学习提出了一种用于对大量小麦赤霉病籽粒样本快速可视化识别的算法,以降低漏检率并提升检测效率。实验分别采集健康小麦和染病小麦469～1 082 nm波段的高光谱图像,通过直方图线性拉伸结合图像分割的方法获取小麦样本的掩膜图像信息。利用Savitzky-Golay平滑去噪法与标准正态变量变换法（SNV）进行数据预处理,通过主成分分析法（PCA）和连续投影法（SPA）进行特征变量提取,筛选特征变量个数分别为4个和8个。在掩膜图像位置采集健康小麦样本与染病小麦样本各400份,其中75%用于建模集,25%用于测试集。采用十折交叉验证法结合线性判别分析法(LDA) 、K-近邻算法（KNN）、支持向量机（SVM）分别建立分类模型,测试集准确率都达到90%以上。随后比较了网格法（GRID）、粒子群算法（PSO）、遗传算法（GA）三种核参数寻优方法对SVM模型的影响,其中,SG-SPA-SVM（PSO）模型分类效果最优,建模集准确率为95.5%,均方根误差为0.212 1,测试集准确率为98%,均方根误差为0.141 4。基于样本点预测的基础之上,对掩膜获得所有小麦样本的光谱曲线进行预测并将识别结果反馈回掩膜中再进行伪彩色显示,实现染病籽粒可视化识别。结果表明,高光谱成像结合SG-SPA-SVM（PSO）算法建立的分类模型可以高效快速、准确无损、可视化的实现小麦赤霉病籽粒识别,为研制小麦赤霉病自动识别设备提供了算法基础。     

Simultaneous high-performance liquid chromatographic determination of visoltricin, acuminatopyrone and chlamydosporols in Fusarium cultures on maize

Visoltricin (VIS), acuminatopyrone (ACP), clamydosporol (CL), isochlamydosporol (ICL) and chlamydospordiol (DIOL), recently characterized Fusarium metabolites, were separated on a polymeric RP-18 column eluted with acetonitrile-0.01% ammonia solution (35:65) at 1 ml/min and detected with a diode-array UV detector. The presence of ammonia in the mobile phase improved the shape of the CL and VIS peaks. The use of a polymeric column was required owing to the basic pH of the mobile phase. Maize cultures of several strains of F. tricinctum and F. chlamydosporum were analysed with this procedure after extraction with aqueous methanol, partitioning with methylene chloride and clean-up with a C₁₈ minicolumn. VIS was produced only by F. tricinctum, whereas ACP and chlamydosporols were produced by both Fusarium species.     

The biocatalytic conversion of 8-hydroxymanzamine A to manzamine A

The selective dehydroxylation of 8-hydroxymanzamine A (1) to form manzamine A (2) can be completed by fermentation with Fusarium solani or Streptomyces seokies. This unique biocatalytic conversion is important due to the fact that manzamine A has more desirable biological activity when assayed in a murine model against malaria.