Gauge invariant derivative expansion of the effective action at finite temperature and density and the scalar field in 2+1 dimensions

A method is presented for the computation of the one-loop effective action at finite temperature and density. The method is based on an expansion in the number of spatial covariant derivatives. It applies to general background field configurations with arbitrary internal symmetry group and space-time dependence. Full invariance under small and large gauge transformations is preserved without assuming stationary or Abelian fields nor fixing the gauge. The method is applied to the computation of the effective action of spin zero particles in 2+1 dimensions at finite temperature and density and in presence of background gauge fields. The calculation is carried out through second order in the number of spatial covariant derivatives. Some limiting cases are worked out.Comment: 34 pages, REVTEX, no figures. Further comments adde

Seedling Blight of Malabar Chestnut caused by Phytophthora Species in Taiwan

馬拉巴栗苗木是我國重要之外銷觀葉植物，主產區在彰化溪洲一帶。近年來，田間栽培的馬拉巴栗苗木經常發生腐敗情形，造成苗木死亡、失編及出口貨品腐敗。本試驗發現疫病菌為引起馬拉巴栗苗木腐敗的重要病原菌之一，它可以感染馬拉巴栗全株，無論在苗期、編苗時期或本田期均可發生，愈年幼的苗木發病愈嚴重。幼苗染病時，葉片、新梢及莖部會出現水浸狀不規則淡褐色病斑，繼之病斑擴展，導致葉片褐化與落葉、新梢與莖部枯萎，甚至造成植株死亡。本田期的病徵主要出現在葉片與根系，造成葉片褐斑與細根腐敗。疫病在苗編時期亦會發生，主要造成根部水浸狀腐敗，苗木失編。田間調查結果顯示約有30%以上的苗圃罹患疫病，本試驗自47 處田區、編苗場及集貨場分離得疫病菌。分離得到的疫病菌主要有兩種，包括Phytophthora palmivora 與Phytophthora nicotianae（= P. parasitica），大部分為A1 配對型，極少部分為A2 配對型。兩種疫病菌在12-34℃均可生長。此外，接種試驗結果顯示，P. palmivora引起的疫病在16-32℃均會發病，最適合發病的溫度為28℃。疫病在多雨期發病嚴重，春天播種的苗木在梅雨季節與夏秋季播種的苗木於颱風季節均容易得病。病害的初次感染源可來自連作田受污染的土壤或鄰近的馬拉巴栗田區，環境合適時，病害一發不可收拾，嚴重時，田間發病率可高達50-75%以上。P. palmivora 與P. nicotianae 引起的馬拉巴栗疫病為國內首度正式報導。 Malabar chestnut (Pachira macrocarpa Schl. et L. H. Bailey) seedlings are important potted ornamental plants for export from Taiwan. The seedlings can be potted alone or braided in groups of three or five. The main production area of Malabar chestnut in Taiwan is Sijhou in Changhua County. In recent year, the production of Malabar chestnut has been impacted with diseases that cause root and basal rots of seedlings, leading to the death of seedlings in the field, loss of braids, and rots of plants in storage container during shipping. Our previous studies indicate that Phytophthora spp. are the major microorganisms that cause the disease. Results of this study showed that Phytophthora spp. were able to infect entire Malabar chestnut plant at any production stages, including seedling, braiding, and growth in the field. The plants were most susceptible at the seedling stage. Symptoms of infected seedlings included water-soaking, irregular-shaped brown lesions on leaves, shoots, and stems. In the field, the disease mainly affected leaves and roots, causing brown foliar lesions and root rot. At the seedling braiding stage, Phytophthora infection caused water-soaking lesions of roots and loss of braids. Our survey showed that more than 30% of the Malabar chestnut nurseries were affected by diseases caused by Phytophthora spp. Isolates of Phytophthora were obtained from 47 locations, including nurseries, cultivation fields, braiding houses, and packaging houses, and identified as Phytophthora palmivora and Phytophthora nicotianae (= P. parasitica). Most of the isolates were A1 mating type, and only a few were A2. Both species could grow at temperature ranging from 12 to 34°C with an optimum growth at 28°C. Inoculation study showed that P. palmivora could cause disease at 16°C to 32°C with the optimum temperature at 28°C. Phytophthora diseases were more serious in wet seasons. Seedlings planted in spring and summer/autumn were most vulnerable due to rainy weather and typhoons. The primary inoculum could come from the infested soils of Malabar chestnut monocropping field and nearby cultivation fields. The Phytophthora diseases of Malabar chestnut were devastating when the environmental conditions were suitable for disease development, reaching infection rates of 50-70%. This is the first official record of Phytophthora diseases of Malabar chestnut caused by P. palmivora and P. nicotianae in Taiwan

Root and foot rot of loquat in Taiwan caused by Phytophthora

Loquat trees growing in central Taiwan were inflicted with a disease causing wilting and death of plants due to severe foot and root rot. The vascular tissues of all infected plants turned brown. Typical as well as atypical isolates of Phytophthora parasitica were isolated from the diseased basal stem and root tissues but not from the discolored vascular tissues. Symptoms observed in the field were reproduced when roots and stems of loquat seedlings were inoculated with zoospores of atypical isolates of P. parasitica; whereas only fibrous root rot resulted from inoculation with typical isolates of P. parasitica. Atypical isolates could be differentiated from the typical isolates of P. parasitica by several characteristics, including colony appearance, partial caducous sporangia, size of oospore, growth at 36 degrees C, mycelial soluble protein patterns, and pathogenicity

Activity and characterization of secondary metabolites produced by a new microorganism for control of plant diseases

Microorganisms capable of utilizing vegetable tissues for growth in soils were isolated and their vegetable broth cultures were individually sprayed directly on leaves to test their ability to control Phytophthora blight of bell pepper caused by Phytophthora capsici. Liquid culture of Streptomyces strain TKA-5, a previously undescribed species obtained in this study, displayed several desirable disease control characteristics in nature, including high potency, long lasting and ability to control also black leaf spot of spoon cabbage caused by Alternaria brassicicolca. The extract was fungicidal to P. capsici but fungistatic to A. brassicicola. It was stable at high temperature and high pH. However, after exposure to pH 2 for 24 h, the extract was no longer inhibitory to P. capsici although it was still strongly inhibitory to A. brassicicola. After treatment with cation or anion exchange resins, the extract lost its inhibitory effect against P. capsici but not A. brassicicola. The results suggest that the extract contained two different kinds of inhibitory metabolites, one against P. capsici with both positive and negative charges on its molecule and another against A. brassicicola with no charges on its molecule. The inhibitory metabolites were soluble in ethanol or methanol but not in water, ether or chloroform. They were dialyzable in the membrane tubing with molecular weight cut-off of 10,000, 1000 or 500 but not 100, indicating that the inhibitors have a molecular weight between 500 and 100. Results also showed that both inhibitors are not proteins

Foodborne disease outbreaks caused by sucrose-nonfermenting and beta-galactosidase-deficient variants of Vibrio cholerae

We reported four foodborne disease outbreaks in Taiwan caused by sucrose-nonfermenting and by beta-galactosidase-deficient variants of non-O1, non-O139 Vibrio cholerae. The sucrose-nonfermenting vibrios collected from three outbreaks were biochemically identified to be V mimicus and the beta-galactosidase-deficient vibrios from an Outbreak to be V alginolyticus. However, molecular methods including DNA-DNA hybridization, fatty acid profile analysis, and sequence analysis of 16S rRNA, oriC, pyrH, recA, and rpoA indicated that these vibrios should be V cholerae. These V cholerae variants carried two hemolysin genes, hlyA and hlx, but contained neither cholera toxin gene, ctx, V mimicus hemolysin gene, vmh, nor then-no-directed hemolysin, tdh. The sucrose-nonfermenting variants of V cholerae shared a high level of genetic relatedness; they could derive from a common clone. In our record from 1995 to date, this was the first time that V cholerae variants were discovered as etiologic agents for foodborne disease outbreaks in Taiwan. (c) 2007 Elsevier B.V. All rights reserved

Paenibacillus taichungensis sp nov., from soil in Taiwan

Among a large collection of Taiwanese soil isolates, a novel Gram-variable, rod-shaped, motile, endospore-forming bacterial strain, strain V10537(T), was subjected to a polyphasic study including 16S rRNA and gyrB gene sequence analysis, DNA-DNA hybridization experiments, cell wall peptidoglycan type, cellular fatty acid composition analysis and comparative phenotypic characterization. 16S rRNA gene sequence analysis indicated that the organism belonged to the genus Paenibacillus. Strain V10537(T) possessed meso-diaminopimelic acid as the diagnostic diamino acid of the peptidoglycan. It contained menaquinone MK-7 as the predominant isoprenoid quinone and anteiso-C(15:0),0 (53.6%) and C(16:0) (19.0%) as the major fatty acids. Phylogenetically, the most closely related species to strain V10537(T) were Paenibacillus pabuli, Paenibacillus xylanilyticus, Paenibaciflus amylolyticus, Paenibacillus barcinonensis and Paenibacillus illinoisensis, with 16S rRNA gene sequence similarities of 99.5, 98.8, 98.3, 98.2 and 98.1 % to the respective type strains. The gyrB gene sequence similarities between strain V10537(T) and these strains were 76.9-85.0%. DNA-DNA hybridization experiments showed levels of relatedness of 8.5-45.6 % between strain V10537(T) and these strains. The DNA G + C content of strain V10537(T) was 46.7 mol%. Strain V10537(T) was clearly distinguishable from other Paenibacillus species and thus represents a novel species of the genus Paenibacillus, for which the name Paenibacillus taichungensis sp. nov. is proposed. The type strain is V10537(T) (=BCRC 17757(T) = DSM 19942(T))