Acute oral intragastric pathogenicity and toxicity in mice of <Emphasis Type="Italic">Paecilomyces fumosoroseus</Emphasis> isolated from whiteflies

Paecilomyces fumosoroseus, monospore culture EH-506/3, isolated in Mexico from Bemisia tabaci whitefly was tested for acute oral intragastric pathogenicity and toxicity in CD-1 mice. Animals were inoculated by gavage with only one dose (10⁸ conidia/animal) of viable (72 mice), heat-killed (24 mice) fungus and compared to 18 control mice. Clinical observations were done daily; mycological and histological tests were performed during necropsies at days 3, 10, 17, and 21 after the inoculation. No mice were clinically ill or died. At the end of the study, their mean weight corresponded to healthy adults. Positive fungal cultures of feces were obtained only 24 h after inoculation. Positive cultures were found in 15 out of 360 organs (liver, spleen, kidney, brain, lung) in 12 of 72 mice inoculated with viable conidia. Gross pathology exhibited splenomegaly and liver paleness in mice inoculated with viable and heat-killed fungus. Non-germinated conidia were observed in studied organs, without any pathological tissue reaction, suggesting no mycological or histopathological evidence of fungal multiplication. The fungus was able to persist, but did not cause permanent damage to the host. This study supports the non-pathogenic/toxic status of P. fumosoroseus EH-506/3 when administered intragastrically in mice.     

Toward sequencing the Tetrahymena genome: exploiting the gift of nuclear dimorphism

Important scientific discoveries have utilized the unique advantages of Tetrahymena thermophila as a research organism. Recently developed molecular genetic manipulations allow full exploitation of the many scientific dividends that would result from having its genome sequenced. As a typical ciliated protozoan, Tetrahymena exhibits "nuclear dimorphism". It possesses two differentiated forms of its nuclear genome: a globally repressed, diploid germline or micronuclear genome, and a polyploid, site-specifically fragmented somatic or macronuclear genome. The macronuclear genome is, in effect, a natural, large-insert library of the micronuclear genome. This presentation describes how the gifts of nuclear dimorphism are being exploited in the experimental analysis of molecular and cell biology. Mechanisms present in humans that are either absent in other eukaryotic microbial model systems, or not as readily accessible in them as in Tetrahymena, are especially relevant. This presentation also reviews unique tools generated by nuclear dimorphism that are being used for genetically and physically mapping the Tetrahymena genome.     

Hyalohyphomycosis caused byPaecilomyces variotii: a case report,animal pathogenicity and ‘in vitro’ sensitivity

A case of cutaneous infection in a 25-year-old male caused byPaecilomyces variotii is described. Animal pathogenicity studies with normal and cortisone-treated mice revealed the predeliction ofP. variotii for skin and liver in both normal and cortisone-treated mice and for lungs and heart only in immunosuppressed mice. 5-fluorocytosine gave the best MIC value forP. variotii in vitro. This report documents for the first time thatP. variotii causes cutaneous infection.     

Optimization of Culture Medium for Sporulation and Biomass Production of a Nematophagous Fungus: Consideration of Nutritional and Environmental Conditions

This study reports the effects of various nutritional and environmental factors on sporulation and biomass of Paecilomyces lilacinus IPC‐P. These factors included carbon and nitrogen sources, carbon‐to‐nitrogen ratios, mineral elements and vitamins together with water potentials, temperatures, dark/light cycles and pH. On the basis of these results, together with a ‘two‐step’ cultivation and orthogonal method, the culture conditions for sporulation of this fungus were optimized. The spore suspension was inoculated on a basal medium (sucrose 19.00 g/l, soy peptone 4.06 g/l, K₂HPO₄ 1.00 g/l, KCl 0.50 g/l, MgSO₄ 0.50 g/l, FeSO₄ 0.01 g/l, agar 13.00 g/l) for 4 days, before being transferred to a sporulation medium (dextrin 2.27 g/l, urea 2.13 g/l, CaCl₂ 3.00 g/l, ZnSO₄·7H₂O 0.01 g/l, agar 13.00 g/l) for a further 4 days under the following environmental conditions: ?3.9 MPa/pH 7/light 24 h/temperature 29°C; these conditions were altered to ?0.3 MPa/pH 6/light 24 h/temperature 23°C in order to obtain better biomass yields. The data presented provide information on the nutrient and environmental requirements of this fungus, which will be essential for its commercial production.     

嗜热四膜虫金属硫蛋白基因MMT2和MTT4的表达规律比较与进化模式分析

多个金属硫蛋白基因异构型已在四膜虫中被鉴定,这些异构型可分为7a和7b两个亚家族。该文利用实时荧光定量PCR技术检测了嗜热四膜虫金属硫蛋白基因MTT2和MTT4在Hg、Cu、Cd、Zn、H2O2暴露下的表达水平,结果显示两者表达规律相似,均为:Cu暴露下上调最高(>200倍),Hg次之,Cd、Zn上调倍数不大,H2O2有下调趋势。此表达规律明显有别于7a亚家族,具有7b亚家族的表达特征。同种诱导物暴露下MTT4的上调表达幅度比MTT2高出数倍,结合生物信息学分析结果,推测可能与MTT2和MTT4上游调控元件(如AP-1、MRE等)的数量差异有关。基于MTT2和MTT4在结构和功能上的高度相似性,推测两者可能是经近期基因复制事件产生,并遵循基因剂量模型进化而来。     

Effect of Host Plant on the Potential ofPaecilomyces fumosoroseus(Deuteromycotina: Hyphomycetes) for Controlling the Silverleaf Whitefly,Bemisia argentifolii(Homoptera: Aleyrodidae) in Greenhouses

We determined host plant effect on susceptibility of the silverleaf whitefly,Bemisia argentifolii, to the entomopathogenic fungusPaecilomyces fumosoroseus. Whiteflies were reared on three vegetable species (cucumber, cabbage, and tomato) and three cultivars of tomato (Heatwave, Better Boy, and Rutgers). Second instars were sprayed with 5 × 10⁴conidia/cm²ofPfr97, aP. fumosoroseusstrain, used as a microbial control agent of whiteflies. Trials were conducted in an experimental greenhouse, where temperature and relative humidity were adjusted to favor infection (22–33°C, and 68–100% RH). Larval susceptibility to fungal infection was high and not significantly affected by the host plant. Mortality was > 70% 1 week after treatment and increased further during the second week. Percentages of cadavers with subsequent production of conidia observed in the greenhouse did not vary significantly either with the host vegetable species (85–93% 7 days after treatment and 99–100% 14 days after treatment), or with the cultivar of tomato (96–97% 7 days after treatment and 99–100% 14 days after treatment). After incubation under optimal laboratory conditions, the percentages based on the total number of sporulating cadavers (includingin situsporulating individuals and cadavers sporulating afterin vitroincubation) were not significantly influenced either by host vegetable or cultivar of tomato. According to the conditions prevailing in the series of experiments with the three vegetable species or in the series of experiments with the three cultivars of tomatoes, the production of newly formed conidia varied from approximately 10,000 to 18,000 conidia/cadaver. However, in both series, there was no significant influence of the host vegetable species or cultivar. The survival of the newly formed conidia harvested 7 days following treatment reached more than 50% but was not affected by host plant. These results indicate thatP. fumosoroseusshows potential as a microbial control agent for controllingB. argentifoliion greenhouse crops.     

斜链拟青霉多糖活性组分的分离及其清除自由基活性

对斜链拟青霉胞外多糖进行体外清除自由基活性研究。利用醇沉法从斜链拟青霉发酵液中醇沉获得斜链拟青霉胞外多糖,经DEAE-纤维素-52柱层析后得到1个主峰P3和2个小峰P1与P2,对主峰P3进行Sephadex G-100柱层析,表明P3为纯化物; 应用DPPH-酶标法和化学发光法分别对P3进行清除DPPH·、·OH和O-2·能力测试。结果表明：P3对DPPH·、·OH和O-2·均具有明显的清除能力,且与浓度呈量效关系,IC50分别为0.083、0.121和0.214 mg/mL。     

粉拟青霉种内RAPD多态性分析*

对来自不同地理来源和不同寄主的 １３株粉拟青霉Ｐａｅｃｉｌｏｍｙｃｅｓ ｆａｎｉｎｏｓｕｓ和其他３种拟青霉及１株球孢白僵菌进行ＲＡＰＤ分析,从ＲＡＰＤ扩增结果可知粉拟青霉种内具丰富的遗传多样型。ＲＡＰＤ扩增指纹图谱能有效地分辨不同菌株的基因型,可用于监测生防效果的菌株示踪。聚类分析结果表明种间的遗传差异要明显大于种内的差异。菌株间差异是和地理来源相关,而和寄主不相关。