Extensive variation in surface lipoprotein gene content and genomic changes associated with virulence during evolution of a novel North American house finch epizootic strain of Mycoplasma gallisepticum

Mycoplasma gallisepticum, a significant respiratory and reproductive pathogen of domestic poultry, has since 1994 been recognized as an emergent pathogen of the American house finch (Carpodacus mexicanus). Epizootic spread and pathognomonic characteristics of house finch-associated Mycoplasma gallisepticum (HFMG) have been studied as a model of an emergent to endemic pathogen in a novel host. Here we present comparative analysis of eight HFMG genomes, including one from an index isolate and seven isolates separated spatially and temporally (1994-2008) across the epizootic, and notably having differences in virulence. HFMG represented a monophyletic clade relative to sequenced poultry isolates, with genomic changes indicating a novel M. gallisepticum lineage and including unique deletions of coding sequence. Though most of the HFMG genome was highly conserved among isolates, genetic distances correlated with temporal-spatial distance from the index. The most dramatic genomic differences among HFMG involved phase-variable and immunodominant VlhA lipoprotein genes, including those variable in presence and genomic location. Other genomic differences included tandem copy number variation of a 5 kbp repeat, changes in and adjacent to the clustered regularly interspaced short palindromic repeats, and small-scale changes affecting coding potential and association of genes with virulence. Divergence of monophyletic isolates from similar time/space in the epizootic indicated local diversification of distinct HFMG sublineages. Overall, these data identify candidate virulence genes and reveal the importance of phase-variable lipoproteins during the evolution of M. gallisepticum during its emergence and dissemination in a novel host in nature, likely mediating an important role at the interface between pathogen virulence and host immunity.

Berberine attenuates doxorubicin-induced cardiotoxicity in mice

This study investigated the effects of berberine, a natural alkaloid, on doxorubicin-induced cardiotoxicity in mice. Mice were injected intraperitoneally with saline 10 ml/kg (n = 10), doxorubicin 2.5 mg/kg (n = 10), 60 mg/kg berberine 1 h before doxorubicin 2.5 mg/kg (n = 10), or 60 mg/kg berberine alone (n = 10) every other day for 14 days. Body weight, general condition and mortality were recorded over the 14-day study period. Electro cardiography was performed before the start of treatment and after 14 days and plasma lactate dehydrogenase (LDH) activity was measured after 14 days. At the end of the study period the heart was excised and examined histologically. An increase in mortality, an initial decrease in body weight, increased LDH activity, prolongation of QRS duration and increased myocardial injury were seen in the doxorubicin-treated group compared with the saline control group. These changes were significantly attenuated by pretreatment with berberine. The study suggests that berberine may have a potential protective role against doxorubicin-induced cardiotoxicity in mice.

First Report of Damping-Off on Basella rubra Caused by Rhizoctonia solani Anastomosis Group 4 in Florida

Indian spinach (Basella rubra L.) is a red stem species of Basella that is cultivated worldwide as an ornamental and the aerial parts are also consumed as a vegetable. In May of 2011, symptoms of damping-off were observed on approximately 10% of the plants at the stem base around the soil line of seedlings in a greenhouse in Homestead, FL. Lesions were initially water soaked, grayish to dark brown, irregular in shape, and sunken in appearance on large plants, causing the infected seedlings to collapse and eventually die. Symptomatic stem tissue was surface sterilized with 0.6% sodium hypochlorite, rinsed in sterile distilled water, air dried, and plated on potato dextrose agar (PDA). Plates were incubated at 25°C in darkness for 3 to 5 days. A fungus was isolated in all six isolations from symptomatic tissues on PDA. Fungal colonies on PDA were light gray to brown with abundant growth of mycelia, and the hyphae tended to branch at right angles when examined under a microscope. A septum was always present in the branch of hyphae near the originating point and a slight constriction at the branch was observed. Neither conidia nor conidiophores were found from the cultures on PDA. The characteristics of hyphae, especially the right angle branching of mycelia, indicate close similarity to those of Rhizoctonia solani (2,3). The internal transcribed spacer (ITS) region of rDNA was amplified with the primers ITS1/ITS4 and sequenced (GenBank Accession No. JN545836). Subsequent database searches by the BLASTN program indicated that the resulting sequence had a 100% identity over 472 bp with the corresponding gene sequence of R. solani anastomosis group (AG) 4 (GenBank Accession No. JF701752.1), a fungal pathogen reported to cause damping-off on many crops. Pathogenicity was confirmed through inoculation of healthy India spinach plants with the hyphae of isolates. Four 4-week-old plants were inoculated with the isolates by placing a 5-mm PDA plug of mycelia at the stem base and covering with a thin layer of the soil. Another four plants treated with sterile PDA served as a control. After inoculation, the plants were covered with plastic bags for 24 h and maintained in a greenhouse with ambient conditions. Four days after inoculation, water-soaked, brown lesions, identical to the symptoms described above, were observed on the stem base of all inoculated plants, whereas no symptoms developed on the control plants. The fungus was isolated from affected stem samples, and the identity was confirmed by microscopic appearance of the hyphae and sequencing the ITS1/ITS4 intergenic spacer region, fulfilling Koch's postulates. This pathogenicity test was conducted twice. R. solani has been reported to cause damping-off of B. rubra in Ghana (1) and Malaysia (4). To our knowledge, this is the first report of damping-off caused by R. solani AG-4 on Indian spinach in Florida and the United States. With the increased interest in producing Asian vegetables for food and ornamental purposes, the occurrence of damping-off on Indian spinach needs to be taken into account when designing programs for disease management in Florida. References: (1) H. A. Dade. XXIX. Bull. Misc. Inform. 6:205, 1940. (2) J. R. Parmeter et al. Phytopathology 57:218, 1967. (3) B. Sneh et al. Identification of Rhizoctonia species. The American Phytopathological Society, St Paul, MN, 1991. (4) T. H. Williams and P. S. W. Liu. Phytopathol. Pap. 19:1, 1976.

Effectiveness of applying arsenate reducing bacteria to enhance arsenic removal from polluted soils by Pteris vittata L

Arsenic is a common contaminant in soils and water. It is well established that the fern Pteris vittata L. is an As hyperaccumulator and therefore has potential to phyroremediate As-polluted soils. Also, it is accepted that rhizosphere microflora play an enhancing role in plant uptake of metallic elements from soils. Studies showed that hydroponiclly grown P. Vittata accumulated arsenite more than the arsenate form of As apparently because arsenate and phosphate are analogues and therefore its absorption is inhibited by phosphate. The objective of this study was to determine whether addition of five different arsenate-reducing bacteria would enhance arsenic uptake by P. vittata grown in arsenic polluted soils in afield experiment. Results showed that addition of the As reducing bacteria promoted the growth of P. vittata, increased As accumulation, activated soil insoluble As, and reduced As leaching compared to the untreated control. Plant biomass increased by 53% and As uptake by 44%. As leaching was reduced by 29% to 71% depending on the As reducing bacterium. The results in their entirety permitted some insight into the mechanisms by which the arsenate reducing bacteria enhanced the effectiveness of P. vittata to remove As from the polluted soil.

Extracellular cyclophilin A may be a potential target to protect against myocardial reperfusion injury

Myocardial reperfusion injury is increasingly recognized as an inflammatory process, characterized by neutrophil recruitment and subsequently excessive release of pro-inflammatory factors. Recently, the extracellular cyclophilin A (CypA) has been showed to play an important role in initiation and development of inflammation by chemo trafficking of leukocytes into inflamed tissues, eliciting massive release of pro-inflammatory cytokines, and inducing production of matrix metalloproteinases. Also, the agents targeting CypA have been demonstrated to promise anti-inflammatory effects in the different experimental models of inflammatory diseases including acute lung injury, rheumatoid arthritis, and atherosclerosis. Therefore, we hypothesize that the extracellular CypA may in some way implicated in the pathogenesis of reperfusion-induced inflammatory process, and the specific inhibitors of the extracellular CypA can provide a protection against the myocardial reperfusion injury.