拟松材线虫对黑松致病性研究

松材线虫病（Ｂｕｒａｐｈｅｌｅｎｃｈｕｓｍｕｃｒｏｎａｔｕｓ）是发生在松树上的一种毁灭性病害 ,目前已在日本、中国、美国、加拿大和韩国等分布 ,并在日本和中国造成巨大的损失。在北美洲 ,松材线虫分布也很广。针叶树中还有一些形态与松材线虫非常相近的伞滑刃线虫 ,统称松材线虫复合种（ＰＷＮＣ） ,其中最常见的是拟松材线虫。拟松材线虫在东亚、美洲、欧洲都有 ,分布极广泛。杂交试验和ＤＮＡ分析证实松材线虫和拟松材线虫有密切的关系 ,能用ＲＡＰＤ和ＲＦＬＰ技术进行区分 ,拟松材线虫的ＤＮＡ有东亚和欧洲两种类型 ,前者主要分…     

松林线虫群体致病性测定和潜伏侵染的探讨

由松材线虫（Ｂｕｒｓａｐｈｅｌｅｎｃｈｕｓｘｙｌｏｐｈｉｌｕｓ）引起的松树萎蔫病 ,是松树上的一种毁灭性病害 ,已在日本、美国、黑西哥、加拿大、韩国发生和流行。目前松材线虫的发生范围还在继续扩大。我国最早在１９８２年秋于南京紫金山的松林中发现该病 ,当年仅见枯树２６０株 ,现已查明在苏、浙、粤、皖、港、台均有分布 ,各地呈迅速扩展蔓延趋势。至１９９９年底该病在我国的发病面积已超过６０万公顷 ,累计死树１６００万株 ,直接经济损失１．２８亿元。ＴｏｍｏｙａＫｉｙｏｈａｒｅ从日本松材线虫分布区内收集到３７个线虫群…     

Sterol glycosides and cerebrosides accumulate in Pichia pastoris, Rhynchosporium secalis and other fungi under normal conditions or under heat shock and ethanol stress

The occurrence of glycolipids such as sterol glycosides, acylated sterol glycosides, cerebrosides and glycosyldiacylglycerols was examined in the three yeast species Candida albicans, Pichia pastoris and Pichia anomala, as well as in the six fungal species Sordaria macrospora, Pyrenophora teres, Ustilago maydis, Acremonium chrysogenum, Penicillium olsonii and Rhynchosporium secalis. Cerebroside was found in all organisms tested, whereas acylated sterol glycosides and glycosyldiacylglycerols were not found in any organism. Sterol glycosides were detected in P. pastoris strain GS115, U. maydis, S. macrospora and R. secalis. This glycolipid occurred in both yeast and filamentous forms of U. maydis but in neither form of C. albicans. This suggests that sterol glycoside is not correlated with the separately grown dimorphic forms of these organisms. Cerebrosides and sterol glycosides from P. pastoris and R. secalis were purified and characterized by mass spectrometry and nuclear magnetic resonance spectroscopy. The cerebrosides are beta-glucosyl ceramides consisting of a saturated alpha-hydroxy or non-hydroxy fatty acid and a Delta4,8-diunsaturated, C9-methyl-branched sphingobase. Sterol glycoside from P. pastoris was identified as ergosterol-beta-D-glucopyranoside, whereas the sterol glucosides from R. secalis contain two derivatives of ergosterol. The biosynthesis of sterol glucoside in P. pastoris CBS7435 and GS115 depended on the culture conditions. The amount of sterol glucoside in cells grown in complete medium was much lower than in cells from minimal medium and a strong increase in the content of sterol glucoside was observed when cells were subjected to stress conditions such as heat shock or increased ethanol concentrations. From these data we suggest that, in addition to Saccharomyces cerevisiae, new yeast and fungal model organisms should be used to study the physiological functions of glycolipids in eukaryotic cells. This suggestion is based on the ubiquitous and frequent occurrence of cerebrosides and sterol glycosides, both of which are rarely detected in S. cerevisiae. We suggest P. pastoris and two plant pathogenic fungi to be selected for this approach.     

Trichothecium roseum的酸碱属性及pH值对其胞外酶活性和致病性的影响

目的：明确粉红单端孢（Trichothecium roseum）侵染果实的酸碱性质,测定3 种pH值孢子悬浮液接种对苹果果实病斑直径及胞外酶活性的影响。方法：用T. roseum接种“富士”苹果,测定果实病斑处的pH值变化。用pH值分别为3、5和7的孢子悬浮液接种果实,观察接种对果实病斑直径及病斑处果胶酶和纤维素酶活性的影响。结果：T. roseum接种后果实病斑处的pH值显著升高,由第0天的3.54升高至第12天的4.84,提高了36.7%。3 种pH值孢子悬浮液接种果实后,以pH 7接种的果实病斑直径最大,第9天时分别高出pH 5与pH 3接种的35.2%与68.0%。pH 7接种的果实病斑处具有最高的果胶酶及纤维素酶活性,第9天时的果胶甲酯酶、果胶甲基多聚半乳糖醛酸酶、多聚半乳糖醛酸酶活性分别为pH 3接种的2.95、1.61 倍和1.68 倍,为pH 5接种的2、1.25 倍和1.39 倍。此外,pH 7接种的果实病斑处纤维素酶和β-葡萄糖苷酶第9天的活性分别为pH 3接种的1.97 倍和1.64 倍,为pH 5接种的1.33 倍和1.3 倍。结论：T. roseum属碱化菌,中性或偏碱环境可提高该菌损伤接种苹果果实病斑处的胞外酶活性,增强其致病性。     

烟草黑胫病菌对甲霜灵的抗药性风险

为了评估烟草黑胫病菌对甲霜灵的抗药性风险,以对甲霜灵敏感和高抗的烟草黑胫病菌240和191为出发菌株,进行了抗性突变频率测定、抗性诱变、抗性水平测定、遗传稳定性、生长速率、致病性测定和适合度等研究。结果表明,烟草黑胫病菌对甲霜灵敏感的240菌株在含10mg/L甲霜灵的CA平板上的抗性突变频率为7.0×10-5。分别以药剂诱变和紫外诱变获得了抗甲霜灵菌株240-YY和240-ZY。对甲霜灵敏感性不同的烟草黑胫病菌适合度测定结果表明,抗性菌株在潜伏期、侵染率、病情指数和病斑面积等方面均具有较高的适合度水平。研究结果显示,烟草黑胫病菌对甲霜灵具有较大的抗药性风险。     

不同湿度下球孢白僵菌对杨毒蛾的致病力

温度在25℃、空气相对湿度分别为(95±5)%、(85±5)%、(75±5)%、(65±5)%时,用球孢白僵菌感染杨毒蛾的2龄幼虫。试验表明,相对湿度越高白僵菌的致病力越高,杨毒蛾幼虫的死亡率也越高,各湿度下幼虫的LT50分别为6.799、8.325、10.672、12.597d。     

食源性沙门氏菌分离株致病性研究和毒力相关基因检测

为研究零售鲜肉源沙门氏菌（Salmonella）优势血清型分离株的致病性及相关毒力基因的相关性,本研 究分别取4 种优势血清型S. derby、S. agona、S. enteritidis、S. typhimurium沙门氏菌分离株对SPF级昆明小鼠进行致 病性实验,采用改良寇氏法计算半数致死量,判断4 种血清型沙门氏菌的毒力,并通过聚合酶链式反应检测实验 菌株中9 种毒力相关基因的分布情况并分析其相关性。结果表明,4 种不同血清型的沙门氏菌分离株对小鼠均有 40%～70%的致死率,S. enteritidis、S. agona、S. derby对昆明小鼠的致病力相似,S. typhimurium较弱,且发现致病 力的强弱与毒力岛SPI-2中的sseL基因密切相关。     

创伤弧菌致病性及致病机制研究进展

创伤弧菌广泛存在于海水和牡蛎等海产品中,具有很强的细胞毒性和溶血性,被美国疾病预防控制中心(CDC)列为三大致病性弧菌之一。本文就创伤弧菌在食品中的污染状况,人类感染途径及临床表现,致病性、致病机制和检测方法等进行综述,以期为该菌感染的预防和治疗提供理论依据。     

国内外食品工业用菌种致病性评价法规比较研究

食品工业用菌种广泛应用于食品及食品添加剂的生产,菌种的安全性直接关系到食品安全和公众健康。致病性是菌种安全性的重要评价指标之一,我国对涉及微生物的新食品原料和添加剂新品种的申报,明确要求提供相关材料,但目前尚无致病性的标准评价方法 ,给食品安全带来潜在危害。本文就目前国内外食品、饲料等领域菌种致病性评价方法进行概述,为我国制定科学合理的食品工业用菌种评价方法提供参考和依据。     

Short communication: Molecular characteristics,antimicrobial susceptibility,and pathogenicity of clinical Nocardia cyriacigeorgica isolates from an outbreak of bovine mastitis

The occurrence of nocardial mastitis, mostly in the context of outbreaks, has been reported in many countries. However, there is a paucity of reports regarding detailed characterization of Nocardia cyriacigeorgica from bovine mastitis. Thus, herein we report characteristics, antimicrobial susceptibility patterns, molecular identification, and pathogenicity of N. cyriacigeorgica isolated from an outbreak of clinical mastitis in a dairy herd in northern China. A total of 182 (80.2%) lactating cows had clinical mastitis with severe inflammation and firmness of the udder, reduced milk production, and anorexia, with no apparent clinical response to common antibiotics. Out of 22 mastitic milk samples submitted to our laboratory, 12 N. cyriacigeorgica were isolated and characterized using standard microbiological analysis, 16S rRNA gene sequencing, random amplified polymorphic DNA PCR analysis, biochemical assays, and antibiotic susceptibility testing. Additionally, in vivo experiments were done to determine pathogenicity of these clinical mastitis isolates. All isolates were resistant to ampicillin, amoxicillin-clavulanic acid, ciprofloxacin, minocycline, rifampicin, and aminoglycosides (type VI pattern). Additionally, intramammary inoculation of mice with N. cyriacigeorgica caused chronic inflammatory changes, including hyperemia, edema, and infiltration of lymphocytes and neutrophils, as well as hyperplasia of lymph nodules in mammary glands. Therefore, we concluded that N. cyriacigeorgica was involved in the current outbreak of mastitis. To our best knowledge, this is the first report to characterize N. cyriacigeorgica isolated from cases of bovine mastitis in China.