Manifestations and mechanisms of myocardial lipotoxicity in obesity.

Environmental and socioeconomic changes over the past thirty years have contributed to a dramatic rise in the worldwide prevalence of obesity. Heart disease is amongst the most serious health risks of obesity, with increases in both atherosclerotic coronary heart disease and heart failure among obese individuals. In this review, we focus on primary myocardial alterations in obesity that include hypertrophic remodelling and diastolic dysfunction. Obesity-associated perturbations in myocardial and systemic lipid metabolism are important contributors to cardiovascular complications of obesity. Accumulation of excess lipid in nonadipose cells of the cardiovascular system can cause cell dysfunction and cell death, a process known as lipotoxicity. Lipotoxicity has been modelled in mice using high-fat diet feeding, inbred lines with mutations in leptin receptor signalling, and in genetically engineered mice with enhanced myocardial fatty acid uptake, altered lipid droplet homoeostasis or decreased cardiac fatty acid oxidation. These studies, along with findings in cell culture model systems, indicate that the molecular pathophysiology of lipid overload involves endoplasmic reticulum stress, alterations in autophagy, de novo ceramide synthesis, oxidative stress, inflammation and changes in gene expression. We highlight recent advances that extend our understanding of the impact of obesity and altered lipid metabolism on cardiac function.

First Report of Leaf Spot Caused by Xanthomonas axonopodis pv. poinsettiicola on Poinsettia (Euphorbia pulcherrima) in Norway.

Poinsettia (Euphorbia pulcherrima) is the biggest flowering potted-plant culture in Norway with approximately six million plants produced yearly. A considerable percentage is produced from imported cuttings. In September 2010, we received diseased poinsettias with necrotic leaf spots from a commercial poinsettia grower in Hordaland County. Leaf spots on the upper sides of leaves were brownish, necrotic, irregular in shape, and surrounded by yellow halos. Small, grayish brown, water-soaked spots were observed on the abaxial sides of the leaves from the same plants. Some of the latter carried crusty, dried residues of bacterial exudates. Leaves were surface sterilized and small pieces were excised from the transition area between healthy and diseased tissue. Leaf pieces were soaked in 0.2 ml of sterile phosphate buffered saline (SPBS) for 30 min. The resulting solution was diluted and streaked on several common media suited for the recovery of plant pathogenic bacteria, among them YDC (yeast dextrose chalk agar). The plates were incubated at 25°C in the dark. After 48 to 72 h, pale yellow, smooth, convex, round, and shiny colonies appeared on YDC. On the basis of plant symptoms and colony morphology, the isolated bacteria were expected to be Xanthomonas axonopodis pv poinsettiicola, which is a known pathogen of poinsettia. One isolate was analyzed by fatty acid methyl ester (FAME) analysis according to Sasser (2) and partial gyrase B sequencing as described by Ah-You et al. (1). A strain of X. axonopodis pv. poinsettiicola (NCPPB 581) from the National Collection of Plant Pathogenic Bacteria (UK) was included as a control in both analyses. The isolates were identical to NCPPB581 with respect to the FAME analysis (species level) and the gyrase B sequence. Furthermore, the gyrB sequence was identical to the sequence of strain LMG 849 in GenBank (Accession No. EU015342.1; identities = 774 of 774). Leaf inoculation of disease-free poinsettia was carried out by spraying a solution (approximately 108 CFU ml-1) on the leaves, covering the plants with wetted plastic bags, and placing the plants in a greenhouse maintained at 21°C for 4 weeks. Leaf spot symptoms consistent with the previously observed ones appeared after 2 weeks of incubation. No symptoms were observed on the negative control plant, which was sprayed with SPBS only. The bacterium was successfully reisolated from the induced symptoms and identified by FAME analysis and gyrase B sequencing. In the period following the first detection, Norwegian poinsettia growers were advised to inspect their produce. Suspected samples were sent to us from 28 producers from around the country. The pathogen was detected at 15 production places. Growers were recommended to disinfect their premises and be vigilant with respect to starting up the new season with healthy propagation material. To our knowledge, this is the first report of X. axonopodis pv. poinsettiicola causing bacterial leaf spot on poinsettia in Norway, providing further data on the occurrence of the disease in Europe. References: (1) N. Ah-You et al. Int. J. Syst. Evol. Microbiol. 59:306, 2009. (2) M. J. Sasser. MIDI Tech. Note No. 102. MIDI, 115 Barksdale Prof. Center, Newark, DE, 1990.

Chalara fraxinea Isolated from Diseased Ash in Norway.

European ash (Fraxinus excelsior), also known as common ash, occurs naturally inland in lower areas of southeastern Norway and along the southern coast of the country. It is important both as a forest and ornamental tree. During the last decade, dieback has become a disastrous disease on F. excelsior in many European countries. The anamorphic fungus Chalara fraxinea T. Kowalski (1), described for the first time from dying ash trees in Poland, is now considered the cause of ash dieback (2). In May of 2008, C. fraxinea was isolated from 1.5 m high diseased F. excelsior in a nursery in Østfold County in southeastern Norway. Symptoms included wilting, necrotic lesions around leaf scars and side branches, and discoloration of the wood. From symptomatic branches, small pieces (approximately 1 cm3) were excised in the transition area between healthy and discolored wood. After surface sterilization (10 s in 70% ethanol + 90 s in NaOCl), the pieces were air dried for 1 min in a safety cabinet, cut into smaller pieces, and placed on media. The fungus was isolated on potato dextrose agar (PDA) and water agar (WA). On PDA, the cultures were tomentose, light orange, and grew slowly (21 mm mean colony diameter after 2 weeks at room temperature). Typical morphological features of C. fraxinea developed in culture. Brownish phialides (14.8 to 30.0 [19.5] × 2.5 to 5.0 [4.1] µm, n = 50) first appeared in the center of the colonies on the agar plugs that had been transferred. The agar plugs were 21 days old when phialides were observed. Abundant sporulation occurred 3 days later. Conidia (phialospores) extruded apically from the phialides and formed droplets. Conidia measured 2.1 to 4.0 (3.0) × 1.4 to 1.9 (1.7) µm (n = 50). The first-formed conidia from each phialide were different in size and shape from the rest by being longer (6 µm, n = 10) and more narrow in the end that first appeared at the opening of the phialide. Internal transcribed spacer sequencing confirmed that the morphological identification was correct (Accession No. EU848544 in GenBank). A pathogenicity test was carried out in June of 2008 by carefully removing one leaf per plant on 10 to 25 cm high F. excelsior trees (18 trees) and placing agar plugs from a 31-day-old C. fraxinea culture (isolate number 10636) on the leaf scars and covering with Parafilm. After 46 days, isolations were carried out as described above from discolored wood that had developed underneath necrotic lesions in the bark and subsequently caused wilting of leaves. All the inoculated plants showed symptoms, and C. fraxinea was successfully reisolated. No symptoms were seen on uninoculated control plants (eight trees) that had received the same treatment except that sterile PDA agar plugs had been used. References: (1) T. Kowalski. For. Pathol. 36:264, 2006. (2) T. Kowalski and O. Holdenrieder, For. Pathol. Online publication, doi: 10.1111/j.1439-0329.2008.00565.x, 2008.

Evaluation of phenotypic and molecular typing techniques for determining diversity in Erwinia carotovora subspp. atroseptica.

A number of phenotypic and molecular fingerprinting techniques, including physiological profiling (Biolog), restriction fragment length polymorphism (RFLP), enterobacterial repetitive intergenic consensus (ERIC) and a phage typing system, were evaluated for their ability to differentiate between 60 strains of Erwinia carotovora ssp. atroseptica (Eca) from eight west European countries. These techniques were compared with other fingerprinting techniques, random amplified polymorphic DNA (RAPD) and Ouchterlony double diffusion (ODD), previously used to type this pathogen. Where possible, data were represented as dendrograms and groups/subgroups of strains identified. Simpson's index of diversity (Simpson's D) was used to compare groupings obtained with the different techniques which, with the exception of Biolog, gave values of 0.46 (RFLP), 0. 39 (ERIC), 0.83 (phage typing), 0.82 (RAPD) and 0.26 (ODD). Of the techniques tested, phage typing showed the highest level of diversity within Eca, and this technique will now form the basis of studies into the epidemiology of blackleg disease.

Identification of pseudomonads from fresh and chill-stored chicken carcasses.

Results of carbon source assimilation tests (17 carbon compounds) led to 88% of pseudomonads from cold-stored chicken carcasses being assigned to one of 17 groups. Of these groups, 13 had combinations of properties identical to, or with readily recognizable degrees of similarity to those of published species/biovars. Two of the four groups having carbon assimilation patterns dissimilar to any known species had cellular fatty acid composition corresponding to Pseudomonas fluorescens, and two to Pseudomonas lundensis or Pseudomonas fragi. The P. fluorescens biovars all had higher amounts of 16:1 cis 9 (21-37%) and 18:1 cis 11 (10-19%), than of 17:0 cyclo (1-17%) and 19:0 cyclo (0-1%). In contrast, for P. lundensis and P. fragi, the relative amounts of these unsaturated acids and cyclopropane acids were reversed. Both the carbon source assimilation tests and the cellular fatty acid composition led to the conclusion that none of the species were dominant, although the P. fluorescens biovars constituted about 50% of the isolated pseudomonads.

Properties of phage-receptor lipopolysaccharide from Pseudomonas morsprunorum.

Lipopolysaccharide (LPS) of Pseudomonas morsprunorum was extracted with hot phenol and purified by repeated centrifuging followed by either block electrophoresis or gel filtration. LPS from a virulent isolate exhibited specific phage inactivation (PI50 = 0.05 mug LPS ml-1), whereas LPS from an avirulent phage-resistant mutant did not. LPS was considered pure when a single band was detected following sodium dodecyl sulphate-cellulose acetate electrophoresis (pH 7.4). It was not phytotoxic when inoculated into cherry leaves at concentrations up to I mg ml-1, but produced weak chlorosis in bean and tobacco at 2 mg ml-1: no visible symptoms appeared after treatment with lower concentrations. The chemical composition of the LPS was partly determined.