Characterization of aerosols containing microcystin

Toxic blooms of cyanobacteria are ubiquitous in both freshwater and brackish water sources throughout the world. One class of cyanobacterial toxins, called microcystins, is cyclic peptides. In addition to ingestion and dermal, inhalation is a likely route of human exposure. A significant increase in reporting of minor symptoms, particularly respiratory symptoms was associated with exposure to higher levels of cyanobacteria during recreational activities. Algae cells, bacteria, and waterborne toxins can be aerosolized by a bubble-bursting process with a wind-driven white-capped wave mechanism. The purposes of this study were to: evaluate sampling and analysis techniques for microcystin aerosol, produce aerosol droplets containing microcystin in the laboratory, and deploy the sampling instruments in field studies. A high-volume impactor and an IOM filter sampler were tried first in the laboratory to collect droplets containing microcystins. Samples were extracted and analyzed for microcystin using an ELISA method. The laboratory study showed that cyanotoxins in water could be transferred to air via a bubble-bursting process. The droplets containing microcystins showed a bimodal size distribution with the mass median aerodynamic diameter (MMAD) of 1.4 and 27.8 mum. The sampling and analysis methods were successfully used in a pilot field study to measure microcystin aerosol in situ.     

Isolation of Streptococcus suis from 2 lambs with a history of lameness

Streptococcus suis was isolated postmortem from 2 lambs with a history of lameness. Identity of S. suis was confirmed by species-specific polymerase chain reaction (PCR) and by 16S rRNA gene sequencing. One isolate was untypable by serotyping and non-encapsulated, while the other isolate was serotype 33. The lambs had come from the same farm, and there was no evidence of contact between the lambs and pigs. Although the natural niche for S. suis is considered to be the pig, a wide range of host species may be affected by this pathogen.     

Adiponectin links adipose tissue function and monocyte inflammatory responses during bovine metabolic stress

The periparturient period of dairy cows is characterized by intense lipid mobilization from adipose tissue leading to increased plasma concentrations of nonesterified fatty acids (NEFA). High NEFA are a predisposing factor for inflammatory based diseases. A major component of these diseases is uncontrolled macrophage/monocyte inflammatory responses. Changes in the endocrine activity of adipose tissue during the periparturient period could impact macrophage function by modifying the secretion of adipokines including adiponectin. Currently, the effects of adiponectin on monocyte activation in dairy cattle are unknown. In humans and rodents, this adipokine regulates monocyte phenotype and alterations in its plasma levels are linked with the development of inflammatory diseases. The objectives of this study were to establish associations between plasma adiponectin expression dynamics and different markers of lipid mobilization during the periparturient period of dairy cows and to characterize the effects of adiponectin on the inflammatory response of bovine monocytes. Plasma adiponectin, NEFA, BHB, albumin, and subcutaneous and retroperitoneal fat depots depth were measured during the periparturient period of dairy cows. In vitro, bovine monocytes were cultured with adiponectin to assess changes in pro-inflammatory responses following LPS stimulation. Results from this study demonstrate that alterations in plasma adiponectin levels in periparturient cattle are inversely correlated with the concentrations of plasma NEFA, an important marker of lipid mobilization. Furthermore, adiponectin exposure significantly decreased monocyte expression of TNFα after LPS stimulation thus markedly reducing their inflammatory response. Reduced plasma adiponectin during the periparturient period could predispose dairy cows to the development of uncontrolled monocyte inflammatory responses.     

A B-cell targeting virus disrupts potentially protective genomic methylation patterns in lymphoid tissue by increasing global 5-hydroxymethylcytosine levels

The mechanisms by which viruses modulate the immune system include changes in host genomic methylation. 5-hydroxymethylcytosine (5hmC) is the catalytic product of the Tet (Ten-11 translocation) family of enzymes and may serve as an intermediate of DNA demethylation. Recent reports suggest that 5hmC may confer consequences on cellular events including the pathogenesis of disease; in order to explore this possibility further we investigated both 5-methylcytosine (5mC) and 5hmC levels in healthy and diseased chicken bursas of Fabricius. We discovered that embryonic B-cells have high 5mC content while 5hmC decreases during bursa development. We propose that a high 5mC level protects from the mutagenic activity of the B-cell antibody diversifying enzyme activation induced deaminase (AID). In support of this view, AID mRNA increases significantly within the developing bursa from embryonic to post hatch stages while mRNAs that encode Tet family members 1 and 2 reduce over the same period. Moreover, our data revealed that infectious bursal disease virus (IBDV) disrupts this genomic methylation pattern causing a global increase in 5hmC levels in a mechanism that may involve increased Tet 1 and 2 mRNAs. To our knowledge this is the first time that a viral infection has been observed to cause global increases in genomic 5hmC within infected host tissues, underlining a mechanism that may involve the induction of B-cell genomic instability and cell death to facilitate viral egress.     

Neonatal alloimmune thrombocytopenia, purpura, and anemia in 6 neonatal piglets

A hemorrhagic diathesis due to neonatal alloimmune thrombocytopenia occurred in a sow herd consisting of F I large white X Landrace females. Colostrum, containing maternal antibodies incompatible with platelet antigens inherited from the sire, was ingested and absorbed by the piglets. Six piglets were affected and displayed signs of lethargy and depression with petechiation, ecchymosis, and severe bruising of the skin. All 6 piglets died or were euthanized by 3 days of age.     

利用AFLP进行“甘蔗属复合体”系统演化和亲缘关系研究

采用AFLP分子标记技术，对“甘蔗属复合体”中4个属16个种的69份来自中国和澳大利亚的甘蔗种质资源材料进行系统演化和亲缘关系分析。2对AFLP引物共检测到173个标记，其中172个为多态标记，多态率达99.4%；通过计算Jaccard相似性系数，用UPGMA和PCA法构建了分子系统树和效应图。结果表明：(1)属间亲缘关系中，甘蔗属与芒属较     

Identification of 1,8-dihydroxynaphthalene melanin in Monosporascus cannonballus and the analysis of hexaketide and pentaketide compounds produced by wild-type and pigmented isolates of the fungus

Monosporascus cannonballus causes root rot and vine decline in muskmelons and watermelons. Wild types of this fungus often undergo degenerative changes that have been associated with yellow to brown pigmentation, hypovirulence, dsRNA infection, and decreased production of perithecia. In this study, degenerate isolates that produced yellow to brown pigments and no perithecia were obtained from wild-type cultures that had been stored for extended periods of time. Cultures of the degenerate isolates were found to accumulate five related hexaketides when grown on potato-dextrose agar (PDA). In contrast, these hexaketides were present only in minute amounts in wild-type cultures unless grown on NaCl-amended PDA. 1,8-Dihydroxynaphthalene melanin was established to be present in wild-type M. cannonballus and absent in the degenerate isolates. Various melanin-related metabolites, however, were produced by the variants. Tricyclazole in PDA cultures blocked melanin biosynthesis by the wild types but had little effect on hexaketide production by the degenerate isolates.