Two novel and potentially endemic species of Phytophthora associated with episodic dieback of Kwongan vegetation in the south‐west of Western Australia

Two novel homothallic species of Phytophthora causing dieback of Kwongan vegetation in south‐west Western Australia are described here as Phytophthora arenaria sp. nov. and Phytophthora constricta sp. nov. DNA sequencing of the ITS rDNA and cox1 gene confirmed that P. arenaria and P. constricta are unique species residing in ITS clades 4 and 9, respectively. Phytophthora arenaria has been isolated from vegetation occurring on the northern sandplains which are warmer and drier than the southern sandplains from which P. constricta has been predominantly isolated, and both species appear morphologically and physiologically well adapted to the ecosystems in which they occur. Both species have been associated mainly with dead and dying Banksia species and the pathogenicity of both P. arenaria and P. constricta to Banksia attenuata was confirmed in this study. The combination of unique DNA sequences, including considerable variation in cox1 sequence data, thick oospore walls and physiological characteristics that appear to be adaptations favouring survival in the harsh Kwongan ecosystem suggest that these species may be endemic to Western Australia.     

Guanidinium and amidinium fungicides: A new class of carbocation mimetic ergosterol biosynthesis inhibitors

A novel class of chemical has been designed with the aim of inhibiting the Δ¹⁴-reductase and Δ⁸-Δ⁷-isomerase enzymes in the ergosterol biosynthesis pathway in fungi. Use was made of knowledge about the mechanisms of both enzymes and the mode of action of known, fungicidal inhibitors of these enzymes. Pioneer examples have been synthesised and have been demonstrated to be potent inhibitors of ergosterol biosynthesis in Ustilago maydis (DC) Corda, acting in the same manner as the commercial fungicide fenpropimorph. They also showed excellent fungicidal activity against Erysiphe graminis DC f. sp. hordei Marchal (powdery mildew of barley) and Puccinia recondita Rob. ex Desm. (wheat leaf rust) in in-vivo glasshouse tests. Using these compounds as a starting point, systematic structural variation has been carried out. Testing of a wide range of analogues at high volume confirms the potential of this class of compound to control mildew and rust pathogens at levels comparable to those of the standards. Correlation of in-vivo and enzymatic data is good and the structure-activity relationship developed for this series of compounds closely parallels that found for the morpholine/piperidine class of fungicides, suggesting a common mode of action.     

Reduction of adult hippocampal neurogenesis is amplified by aluminum exposure in a model of type 2 diabetes

In this study, we investigated the effects of chronic aluminum (Al) exposure for 10 weeks on cell proliferation and neuroblast differentiation in the hippocampus of type 2 diabetic rats. Six-week-old Zucker diabetic fatty (ZDF) and Zucker lean control (ZLC) rats were selected and randomly divided into Al- and non-Al-groups. Al was administered via drinking water for 10 weeks, after which the animals were sacrificed at 16 weeks of age. ZDF rats in both Al- and non-Al-groups showed increases in body weight and blood glucose levels compared to ZLC rats. Al exposure did not significantly affect body weight, blood glucose levels or pancreatic β-cells and morphology of the pancreas in either ZLC or ZDF rats. However, exposure to Al reduced cell proliferation and neuroblast differentiation in both ZLC and ZDF rats. Exposure to Al resulted in poor development of the dendritic processes of neuroblasts in both ZLC and ZDF rats. Furthermore, onset and continuation of diabetes reduced cell proliferation and neuroblast differentiation, and Al exposure amplified reduction of these parameters. These results suggest that Al exposure via drinking water aggravates the impairment in hippocampal neurogenesis that is typically observed in type 2 diabetic animals.     

Effects of surface treatment of ramie fibers in a ramie/poly(lactic acid) composite

The chemical and morphological properties of ramie fibers treated by chemical surface modification were examined with Fourier transform infrared (FT-IR) spectroscopy. The mechanical and thermal decomposition properties were evaluated with respect to tensile strength, tensile modulus and thermogravimetric analysis (TGA). Surface morphological changes were investigated with scanning electron microscopy (SEM). Finally, the capabilities of composites reinforced with various chemically treated fibers were analyzed by investigating tensile and impact strengths. Additionally, the thermal mechanical properties of the composites were investigated with thermal mechanical analysis (TMA). Based on the results of these analyses, we concluded that pectin, lignin and hemicellulose were removed and thermal stability was increased with chemical treatments. The composites reinforced with ramie fiber showed better properties compared with pure PLA matrix with respect to tensile and impact strengths. The peroxide-treated fiber composite had the smallest thermal expansion.     

Changes in peripheral leukocytes enzymes activity and plasma metabolite concentrations in growing Holstein calves

Plasma metabolite and immunoreactive insulin concentrations and activities of enzymes related to energy metabolism in peripheral leukocytes were measured in growing Holstein calves. A ratio of girth of abdomen divided by girth of thorax (A/T ratio) of calves was significantly elevated after weaning, and the A/T ratio maybe a good indicator to evaluate rumen development. Plasma glucose and free fatty acid concentrations were changed in calves accompanying change in feeding. Activities of lactate dehydrogenase with pyruvate as substrate (LDH-P) and hexokinase (HK) in cytosolic fractions of peripheral leukocytes decreased significantly after weaning the calves reflecting the change of energy source from milk replacer with high percentages of fat and glucose and lactose as absorbable carbohydrate to pelleted feed containing starch as less absorbable carbohydrate and roughage. Some peripheral leukocyte enzymes such as LDH and HK may be good indicators to evaluate changes in energy metabolism of growing calves.     

Identification and determination of antigenic proteins of Korean ranavirus-1 (KRV-1) using MALDI-TOF/TOF MS analysis

Ranaviruses are serious pathogens of fish, amphibians, and reptiles, and pose a major threat to global biodiversity. A ranavirus isolated from tissues of diseased tadpoles and frogs in Gangwon province, Korea, in 2006 and 2007, was designated Korean ranavirus-1 (KRV-1) and was infectious in a variety of fish cell lines with highest titers (10¹⁰ TCID₅₀/ml) in Epithelioma papulosum cyprini cells (EPCs) and baby hamster kidney-21 (BHK-21) cells. Bullfrog (Rana catesbeiana) tadpoles challenged by immersion in 10⁵ TCID₅₀/ml of KRV-1 showed 60% mortality within 10 days. SDS-PAGE of frog virus 3 (FV3) and KRV-1 proteins yielded several bands 35-49 kDa in size, which were identified as major capsid proteins (MCPs) by MALDI-TOF MS. Immunoblotting of FV3 proteins showed antigenic bands 34 kDa and 93 kDa in size which were identified by MALDI-TOF/TOF MS as MCP and neurofilament triplet H1-like protein (NF-H1), respectively. In KRV-1, antigenic bands at 32 kDa, 69 kDa, and 72 kDa were identified as MCP, Hypothetical protein, and NF-H1, respectively. The genes encoding these KRV-1 proteins were sequenced. KRV-1 appeared to be closely related to the soft-shelled turtle iridovirus (STIV), based on alignments of amino acid sequences from various ranaviruses. Variability in ranavirus antigenic proteins was apparent in an earlier study. It is expected that use of the methods employed here, together with the results of the present work, will contribute to an understanding of the pathogenesis of ranaviruses, and will further the development of DNA- or protein-based bait vaccines for conservation of natural habitats.     

Combination of a simple differential medium and toxA-specific PCR for isolation and identification of phytopathogenic Burkholderia gladioli

The NGM medium developed in a previous study was used for differential isolation of Pectobacterium chrysanthemi, Burkholderia gladioli, and B. glumae. P. chrysanthemi developed blue colonies, and all B. gladioli and B. glumae strains tested produced diffusible yellow pigments on the NGM medium, easily distinguishable from other Burkholderia spp. and plant pathogenic bacteria. The produced yellow pigments contained a toxoflavin determined by the TLC and orchid leaf chlorosis tests. A specific oligonucleotide primer pair was designed for the detection of toxA, which is involved in toxoflavin biosynthesis. All B. gladioli and B. glumae strains tested contained toxA as determined by PCR amplification. No amplification was observed with other plant pathogenic bacteria. In addition, the toxA-based species-specific PCR assays, based on the nucleotide sequence differences in the promoter region of toxA, were developed for identification of B. gladioli and B. glumae, respectively. The NGM medium and the toxA-based PCR assays were used to determine the causal agents of leaf rot of Phalaenopsis and Oncidium orchids at three cultivation areas in Taiwan. It was found that both P. chrysanthemi and B. gladioli are important pathogenic bacteria of orchid leaf rot in Taiwan. The results indicate that the combination of NGM medium with toxA-based PCR assays is a newly designed and efficient method for isolation and identification of leaf rot pathogenic bacteria especially from plant hosts on which P. chrysanthemi and B. gladioli (or B. glumae) could cause symptoms.     

复合益生素对生长育肥猪生产性能、盲肠菌群及代谢产物的影响

试验旨在研究饲粮中添加复合益生素(JS菌)对生长育肥猪生产性能、盲肠菌群、挥发性脂肪酸及蛋白质腐败产物的影响。试验选择120头体重10 kg左右的健康DLY仔猪,随机分为对照组、抗生素组、0.1%JS菌组和0.2%JS菌组,每组5个重复。结果表明:与对照组相比,添加0.2%JS菌显著提高试猪30~50 kg阶段的平均日增重和采食量(P0.05);添加0.1%JS菌显著提高试猪80~100 kg阶段的平均日增重(P0.05);从试验全期来看,抗生素组、0.1%JS菌组和0.2%JS菌组试猪平均日增重和采食量均有所提高,但各组间差异不显著(P0.05)。添加JS菌趋于增加盲肠内容物乳酸杆菌数量,减少大肠杆菌数量(P0.05),从而提高二者的比值,分析PCR-DGGE图谱发现添加JS菌对菌群多样性和相似性也有一定影响。与对照组相比,0.1%JS菌组和0.2%JS菌组盲肠内容物乙酸含量分别提高2.35倍和2.99倍,丁酸含量分别提高58.87%和62.10%,挥发性盐基氮含量分别降低31.91%和28.53%(P0.05)。在本试验条件下,添加JS菌对生长育肥猪的生产性能有一定改善,效果与抗生素基本相当,这可能与其对肠道健康的保护作用有关。