病原菌毒素对植物的致病作用

病原菌在侵染植物的过程中产生的毒素一向被认为是致病的重要因子，然而对毒素致病作用的确定却是一个复杂的问题，毒素在一般生物测定中表现出来的对植物组织的伤害与破坏作用并不一定代表其具备致病力的密切相关，但是对于具体毒素在相应病种中的作用程度及对致病力的贡献大小还需要一些更严格的试验予以确定。     

Correlation between Chemical Structure and Biological Activity of Host-Selective Plant Pathogen Mycotoxins

Toxin, one of the most important factors of plant fungal disease, has attracted much attention of many academicians who have been studying pathogen mycotoxin in deep research. The paper summarized chemical structures of some host-selective plant pathogen mycotoxins discovered in recent years and the correlation between biological activity and chemical structure of toxin.     

纵坑切梢小蠹伴生菌危害机理的研究

该文对纵坑切梢小蠹伴生菌Leptographium yunnanense的危害机理作了初步研究，结果表明，L.yunnanense在与小伴随侵入后，产生致病毒素对寄主树林进行危害，从而辅助纵坑切梢小蠹成功定殖于寄主树木内，该毒素在低浓度条件下仍维持一定的致病力，进一步表明伴生菌在小蠹虫成功蛀害的过程中具有重要的作用。     

Clinical and pathologic features of acute bovine liver disease in Australia

Acute bovine liver disease (ABLD) is a sporadic hepatic disease affecting cattle in southern Australia, characterized histologically by striking periportal hepatocellular necrosis. The cause of ABLD is unknown; however, the seasonality and acute presentation of outbreaks suggest mycotoxin involvement. We describe here the clinical and pathologic findings of ABLD in 45 naturally affected cattle from 13 outbreaks occurring from 2010 to 2019 in Victoria, Australia. Outbreaks occurred in herds located along the southern coastal plain of Victoria and were observed most frequently in lactating dairy cattle. Clinical signs commonly included a combination of mild photosensitization, progressive neurologic signs, and hypogalactia, which preceded death by ≤ 48 h. All affected animals had marked elevations in activities of glutamate dehydrogenase, aspartate aminotransferase, and gamma-glutamyl transferase. At autopsy, the most common lesions were serosal petechiae and/or gastrointestinal hemorrhage, and hepatomegaly with a pronounced hepatic reticular pattern. The principal histologic lesion was widespread—severe periportal hepatocellular coagulative necrosis and erythrocyte pooling—which often extended to massive necrosis. Lesions in other organs were uncommon. Our study of ABLD suggests involvement of a potent hepatotoxin that is either directly cytopathic or requires bioactivation by periportal-specific enzymes.     

玉米大斑病菌HST生物合成基因簇的结构和表达分析

【目的】分析玉米大斑病菌寄主选择性毒素（host selective toxin,HST）生物合成基因簇Cluster 397.3的结构,以及该基因簇组成基因在玉米大斑病菌侵染过程中的表达情况,为玉米大斑病菌HST的结构和功能研究奠定基础。【方法】以玉米大斑病菌23号生理小种et28a和01-23菌株,1号生理小种ny001和01-11菌株,玉米感病自交系B37为材料,利用antiSMASH技术预测玉米大斑病菌次生代谢产物合成基因簇,通过Synteny共线性分析获得玉米大斑病菌HST生物合成基因簇Cluster 397.3,并对其基因组成和结构进行分析,再利用RNA-Seq技术分析该基因簇的组成基因在玉米大斑病菌侵染玉米叶片3,5,7,10 d的表达情况。【结果】玉米大斑病菌次生代谢产物合成基因簇Cluster 397.3与交链链格孢（Alternaria alternata）ACT-毒素合成基因簇有保守的共线性,含有1个聚酮合酶（PKS）、1个氨基甲酰磷酸合成酶（CPS）、1个短链脱氢酶/还原酶（SDR）、1个锌结合氧化还原酶（ZOR）、1个保守假定蛋白（CHP）、2个细胞色素P450（P450）及2个耐药转运蛋白（DRT）等9个基因。其中PKS与ACT-毒素合成酶基因ACTTS3同源,编码的聚酮合酶包括PksD、PS-DH、Methyltransf_12、PKS_KR、PKS_NbtC superfamily和NADB_Rossmann superfamily 6个典型结构域。RNA-Seq分析结果表明,将玉米大斑病菌接种玉米叶片3,5,7,10 d后,Cluster 397.3组成基因均能表达,且以3 d时表达量整体较高;除CHP基因外,01-11菌株中基因表达量均显著高于01-23菌株。【结论】Cluster 397.3基因表达差异与玉米大斑病菌生理小种的分化和致病特异性有关,该基因簇可能参与了玉米大斑病菌寄主选择性毒素的生物合成。     

粮油作物真菌毒素污染现状及控制

真菌毒素是由某些丝状真菌产生的致癌、致畸、致突变的毒性副产物,对玉米、水稻、小麦、花生、大豆和油菜等多种粮油作物具有极大的危害性,严重威胁环境安全、食品安全和人类健康。随着世界人口的急剧增加和主要农作物种植面积的扩大,粮油农产品中的真菌毒素污染有逐年加重的趋势。本文对粮油作物中主要真菌毒素种类及污染现状进行了综述,分析了导致真菌毒素污染加重的环境影响因子,提出了粮油作物不同生长时期真菌毒素污染防控措施,特别是生物防控技术,展望了真菌毒素污染生物防控的作用模式及类型。     

Paralytic shellfish poisoning toxin analysis of the genus <Emphasis Type="Italic">Alexandrium</Emphasis> (Dinophyceae) occurring in Korean coastal waters

ABSTRACT:   Paralytic shellfish poisoning (PSP) toxins produced by Alexandrium isolates from Korea were analyzed by high-pressure liquid chromography. Species designation of the regional isolates was determined by morphological criteria and ribotyping inferred from sequences of the 28S rDNA D1-D2 region. Toxin analysis performed at the exponential growth phase, revealed that the two strains of A. fraterculus were non-toxic, while the strains of A. tamarense and A. catenella were toxic. Toxic isolates DPC7 and DPC8 of A. catenella produced GTX1, 2, 3, 4, 5, dcGTX2, 3, C1, 2, neoSTX and STX with trace or non-detectable levels of C3 and C4, while isolates UL7, KDW981, SJW97043, SJW97046, KJC97111 and KJC97112 of A. tamarense produced GTX1, 2, 3, 4, dcGTX3, C1, 2, neoSTX with trace or non-detectable levels of C3, 4, dcSTX and STX, and no GTX5 and dcGTX2. The major toxins produced by A. catenella were C1 +2, and those of A. tamarense were C1 +2 and GTX4 in most of the isolates. A. tamarense strains other than SJW97046 produced a relatively high proportion of carbamate toxins, reflecting the high toxicity scores of shellfish intoxication in sampled coastal areas. Two representative toxic isolates, A. tamarense SJW97043 and A. catenella DPC7, were cultured for 30 days in batch mode and subjected to toxin analysis at 5-day intervals. Comparison of toxin productivity in terms of total toxin content, toxin components, and their variations with culture age revealed marked differences between the two strains.     

福建沿海文蛤产地和暂养地贝类素毒化状况

采集福建沿海文蛤产地，暂养地的文蛤，结合分析其所生长的个体情况，检测其DSP和PSP，结果表明：福建沿海文蛤产地和暂养地未出现的DSP，PSP毒化状况。     

Development of a multiplex loop-mediated isothermal amplification assay to detect shiga toxin-producing Escherichia coli in cattle

A multiplex loop-mediated isothermal amplification (mLAMP) assay was developed for simultaneous detection of the stx1 and stx2 genes and applied for detection of shiga toxin-producing Escherichia coli (STEC) in cattle farm samples. Two target genes were distinguished based on T_m values of 85.03 ± 0.54℃ for stx1 and 87.47 ± 0.35℃ for stx2. The mLAMP assay was specific (100% inclusivity and exclusivity), sensitive (with a detection limit as low as 10 fg/µL), and quantifiable (R² = 0.9313). The efficacy and sensitivity were measured to evaluate applicability of the mLAMP assay to cattle farm samples. A total of 12 (12/253; 4.7%) and 17 (17/253; 6.7%) STEC O157, and 11 (11/236; 4.7%) non-O157 STEC strains were isolated from cattle farm samples by conventional selective culture, immunomagnetic separation, and PCR-based culture methods, respectively. The coinciding multiplex PCR and mLAMP results for the types of shiga toxin revealed the value of the mLAMP assay in terms of accuracy and rapidity for characterizing shiga toxin genes. Furthermore, the high detection rate of specific genes from enrichment broth samples indicates the potential utility of this assay as a screening method for detecting STEC in cattle farm samples.     

Multiple‐Aetiology Enteric Infections Involving Non‐O157 Shiga Toxin‐Producing Escherichia coli – FoodNet, 2001–2010

We describe multiple‐aetiology infections involving non‐O157 Shiga toxin‐producing Escherichia coli (STEC) identified through laboratory‐based surveillance in nine FoodNet sites from 2001 to 2010. A multiple‐aetiology infection (MEI) was defined as isolation of non‐O157 STEC and laboratory evidence of any of the other nine pathogens under surveillance or isolation of >1 non‐O157 STEC serogroup from the same person within a 7‐day period. We compared exposures of patients with MEI during 2001–2010 with those of patients with single‐aetiology non‐O157 STEC infections (SEI) during 2008–2009 and with those of the FoodNet population from a survey conducted during 2006–2007. In total, 1870 non‐O157 STEC infections were reported; 68 (3.6%) were MEI; 60 included pathogens other than non‐O157 STEC; and eight involved >1 serogroup of non‐O157 STEC. Of the 68 MEI, 21 (31%) were part of six outbreaks. STEC O111 was isolated in 44% of all MEI. Of patients with MEI, 50% had contact with farm animals compared with 29% (P < 0.01) of persons with SEI; this difference was driven by infections involving STEC O111. More patients with non‐outbreak‐associated MEI reported drinking well water (62%) than respondents in a population survey (19%) (P < 0.01). Drinking well water and having contact with animals may be important exposures for MEI, especially those involving STEC O111.