Identification and characterization of a novel etiological agent of mango malformation disease in Mexico, Fusarium mexicanum sp. nov

The primary objective of this study was to characterize Fusarium spp. associated with the economically devastating mango malformation disease (MMD) in Mexico. In all, 142 Fusarium strains were isolated from symptomatic mango inflorescences and vegetative tissues in eight geographically diverse Mexican states from 2002 through 2007. Initially, all the Mexican isolates were screened for genetic diversity using appolymerase chain reaction and random amplified polymorphic DNA markers and were grouped into seven distinct genotypes. Based on results of these analyses, evolutionary relationships and species limits of the genetically diverse MMD-associated Fusarium spp. were investigated using multilocus DNA sequence data and phylogenetic species recognition. Maximum parsimony analyses of a five-locus data set comprising 5.8 kb of aligned DNA sequence data indicated that at least nine phylogenetically distinct Fusarium spp. within the Gibberella fujikuroi species complex are associated with MMD, including one species within the African clade (Fusarium pseudocircinatum), two species within the Asian clade (F. mangiferae and F. proliferatum), and at least six species within the American clade (F. sterilihyphosum and five undescribed Fusarium spp.). Molecular phylogenetic analyses indicate that a novel genealogically exclusive lineage within the American clade was the predominant MMD associate in Mexico. This new Fusarium sp. caused MMD and could be distinguished from all other known species morphologically by the production of mostly sterile, coiled hyphae which are typically associated with sporodochial conidiophores together with unbranched or sparsely branched aerial conidiophores. Koch's postulates were completed for isolates of the new species on nucellar seedlings of mango cv. Ataulfo. This pathogen is formally described herein as F. mexicanum.     

Hsp70 enhances presentation of FMDV antigen to bovine CD4+ T cells in vitro

Foot-and-mouth disease virus (FMDV) is the causative agent of a highly contagious acute vesicular disease affecting cloven-hoofed animals, including cattle, sheep and pigs. The current vaccine induces a rapid humoral response, but the duration of the protective antibody response is variable, possibly associated with a variable specific CD4⁺ T cell response. We investigated the use of heat shock protein 70 (Hsp70) as a molecular chaperone to target viral antigen to the Major Histocompatibility Complex (MHC) class II pathway of antigen presenting cells and generate enhanced MHC II-restricted CD4⁺ T cell responses in cattle. Monocytes and CD4⁺ T cells from FMDV vaccinated cattle were stimulated in vitro with complexes of Hsp70 and FMDV peptide, or peptide alone. Hsp70 was found to consistently improve the presentation of a 25-mer FMDV peptide to CD4⁺ T cells, as measured by T cell proliferation. Complex formation was required for the enhanced effects and Hsp70 alone did not stimulate proliferation. This study provides further evidence that Hsp70:peptide complexes can enhance antigen-specific CD4⁺ T cell responses in vitro for an important pathogen of livestock.     

City sanitation and socioeconomics predict rat zoonotic infection across diverse neighbourhoods

Rat‐associated zoonoses transmitted through faeces or urine are of particular concern for public health because environmental exposure in homes and businesses may be frequent and undetected. To identify times and locations with greater public health risks from rats, we investigated whether rat characteristics, environmental features, socioeconomic factors, or season could predict rat infection risk across diverse urban neighbourhoods. In partnership with a pest management company, we sampled rats in 13 community areas along an income gradient in Chicago, a large city where concern about rats has increased in recent years. We collected kidneys for Leptospira spp. testing and colon contents for aerobic bacteria such as Salmonella spp. and Escherichia coli. Of 202 sampled rats, 5% carried Leptospira spp. and 22% carried E. coli. Rats were significantly more likely to carry Leptospira spp. on blocks with more standing water complaints in higher‐income neighbourhoods (OR = 6.74, 95% CI: 1.54–29.39). Rats were significantly more likely to carry E. coli on blocks with more food vendors (OR = 9.94, 2.27–43.50) particularly in low‐income neighbourhoods (OR = 0.26, 0.09–0.82) and in the spring (OR = 15.96, 2.90–88.62). We detected a high diversity of E. coli serovars but none contained major virulence factors. These associations between environmental features related to sanitation and infection risk in rats support transmission through water for Leptospira spp. and faecal–oral transmission for E. coli. We also found opposing relationships between zoonotic infection risk and income for these two pathogens. Thus, our results highlight the importance of sanitation for predicting zoonotic disease risks and including diverse urban areas in pathogen surveillance to mitigate public health risks from rats.     

Effects of benomyl on vesicular‐arbuscular mycorrhizal infection of red clover (Trifolium pratense L.) and consequences for phosphorus inflow.

The roots of red clover plants inoculated with the vesicular‐arbuscular mycorrhizal fungus Glomus clarus Nicolson & Schenck were treated with a drench of benomyl at a time when mycorrhizal infection was already well established. Benomyl halted further infection and reduced phosphorus inflow by one order of magnitude compared to untreated controls. The fungicide also decreased the rate of plant growth probably as a consequence of reduced phosphorus inflow.     

Flaxleaf fleabane (Conyza bonariensis) populations have developed glyphosate resistance in north-east Australian cropping fields

In recent years flaxleaf fleabane has become a widespread and difficult-to-control weed in no-tilled fallowed fields, where weeds are controlled by applications of glyphosate, in annual cropping systems of north-east Australia. Fifty-two populations, collected in a national survey from agricultural and non-agricultural areas, were tested in two glyphosate dose-response pot experiments. In two subsequent pot experiments, a sub-set of these populations was tested with a field rate of glyphosate when weeds of two ages were grown at different soil moistures. In the first and second experiments, most populations collected from chemical fallowed or cropped fields in north-east Australia had GR₅₀ (estimated dose for 50% biomass reduction) values three to six times greater than the susceptible populations, indicating low levels of glyphosate resistance. Several populations from roadsides adjacent to chemical fallowed or cropped fields also had higher GR₅₀ values, indicating movement of seeds from resistant plants. In the third experiment, weed biomass of all populations from chemical fallowed or cropped fields was 70-98% of unsprayed compared to 2-3% for the susceptible populations, irrespective of weed age or soil moisture. In the fourth experiment which treated older weeds, the response of several resistant populations to glyphosate was unaffected by differences in weed age and soil moisture, whereas the biomass of the other resistant populations was greater following spraying of older and/or moisture stressed plants compared with smaller non-stressed plants. Thus, exclusive reliance on glyphosate for fallow weed control in this region has resulted in the evolution of resistance in flaxleaf fleabane populations in a cropping system with annual non-transgenic crops. Prolific production of windborne seeds, combined with poor control associated with spraying large moisture-stressed weeds, is likely to have contributed also to flaxleaf fleabane becoming such a problem weed.     

Echinacea alkylamides modulate induced immune responses in T-cells

The effects of Echinacea and several of its phytochemical components on NFkappaB expression by Jurkat cells (a human T-cell line) were investigated in vitro. In the absence of stimulation, Echinacea and its components exerted no significant effect on basal NFkappaB expression levels. In the presence of endotoxin (LPS), NFkappaB expression was decreased. However, this decrease was significantly reversed by treatment with cichoric acid, an Echinacea root extract (prepared from both Echinacea angustifolia and Echinacea purpurea) and the alkylamide fraction derived from this combination. For the phorbol myristate acetate stimulation of Jurkat cells, effects on NFkappaB expression were mixed. Depending on the concentration, cichoric acid and a 2,4-diene alkylamide significantly induced NFkappaB levels, whereas a 2-ene alkylamide caused a significant inhibition. In contrast, both the Echinacea and the mixed alkylamide fraction exerted no effect. The alkylamide results indicate that the two basic forms of these compounds present in Echinacea may have opposing effects. These opposing effects demonstrate the importance of a knowledge, not only of the phytochemical make-up of a herbal preparation, but also of the actions of each component and the consequences of differing relative amounts in the preparation being investigated.     

Effects of ram preexposure and ram breed on fertility of ewes in summer breeding

Suffolk x Rambouillet ewes were used in two consecutive years to test the ability of Dorset and Suffolk yearling rams to stimulate ovulation and estrus in early summer (late June and July) breeding. After spring weaning about June 1, ewes were randomly divided into three groups and for 2 wk either were isolated from rams or were preexposed to either yearling Dorset or Suffolk rams by penning of rams in proximity to ewes. Ewes then were rerandomized into two groups for joining with either yearling Dorset or Suffolk rams fitted with marking harnesses. Serum progesterone profiles and crayon marks were used as indicators of ovulation and estrus. Overall lambing rate was not different among preexposure treatments for the 2 yr. However, early lambing rate (in the first 14 d of lambing season) was significantly affected by preexposure group (24% for Dorset vs 9% for Suffolk and 10% for isolation), especially in the 2nd yr (31% for Dorset vs 8% for both Suffolk and isolation). Ewes preexposed to Dorsets also lambed 10 d earlier (P less than .05) than ewes preexposed to Suffolks in yr 2, but the groups did not differ in yr 1. Ewes exposed to Dorset rams for breeding had higher overall lambing rates than ewes bred to Suffolks (75% vs 54%), especially in the 1st yr (77% vs 48%). Lambs sired by Dorset rams were born 6 d earlier in yr 1 (P less than .05) but only 1 d earlier in yr 2. Data from both years indicate that Dorsets are superior to Suffolks in ability to sire lambs in fall lambing systems.     

Clinical assessment of leukocytosis: distinguishing leukocytoses caused by inflammatory, glucocorticoid, physiologic, and leukemic disorders or conditions.

The four major types of leukocytoses are inflammatory, glucocorticoid-associated, catecholamine-associated, and neoplastic. These leukocytoses are distinguished by leukocyte concentrations, microscopic features of leukocytes, and associations with other laboratory data. All laboratory findings need to be interpreted within the context of the case information, including signalment, history, and physical examination findings. Newer assays are being used to differentiate the different forms of leukocyte neoplasia and to distinguish between hyperplastic and neoplastic proliferations.