Determination of deoxynivalenol and nivalenol chemotypes of Fusarium culmorum isolates from England and Wales by PCR assay

Functioning Tri13 and Tri7 genes are required for the production of nivalenol and 4-acetyl nivalenol, respectively, in Fusarium species producing type B trichothecenes. Mutations have been identified in isolates which are able to produce deoxynivalenol (DON) but unable to convert this to nivalenol (NIV). In such isolates of Fusarium culmorum , the Tri7 gene is deleted entirely. PCR assays specific for functional and nonfunctional/deleted versions of Tri7 and Tri13 were used to determine the ability of 153 single spore isolates of F. culmorum to produce the 8-ketotrichothecenes deoxynivalenol and nivalenol. The isolates were collected from 76 different locations across England and Wales between 1994 and 2002. Four isolates were also obtained from one field in Scotland. Both DON and NIV chemotypes of F. culmorum were identified, with DON chemotypes predominating overall. In addition, all DON chemotypes were shown to produce 3-acetyl DON using primer sets developed to Tri3 . From fields where more than one F. culmorum isolate was obtained, isolates were not exclusively of a single chemotype. Differences in the distribution of DON and NIV chemotypes were identified, with a greater proportion of NIV chemotypes present in the south and west of England and Wales, whereas a greater proportion of DON chemotypes were found in the north and east of England. Seasonal differences in the ratio of DON:NIV chemotypes were indicated. However, these were related to seasonal variation in the distribution of F. culmorum .     

Prospects for strain improvement in entomopathogenic fungi

The deployment of entomopathogenic fungi for the control of insect pests offers an environmentally-acceptable strategy. Major obstacles to their application include variability in effectiveness due to uncontrolled environmental parameters (temperature, humidity) and development of suitable formulation techniques. Strains differ considerably in genetic ability to cause mortality and to spread within populations. Pathogenicity is the result of the interaction of numerous individual traits determining germination and penetration, followed by successful growth within the target host, which is a prerequisite for induction of mortality. No effective singlegene determined toxin has been reported for entomopathogenic fungi, but the application of gene cloning techniques for specific proteases is a likely future development. Genetic manipulation techniques, designed to recombine complex traits associated with pathogenicity via the parasexual cycle, are described here in relation to successful steps achieved in strain improvement programmes which involve: (a) Verticillium lecanii (Zimm.) Viegas against the glasshouse whitefly: Trialeurodes vaporariorum and the aphid Macrosiphoniella sanborni; (b) Metarhizium anisopliae (Metsch.) Sorokin against the rice brown planthopper Nilaparvata lugens.     

Role of bacteria in the pathogenesis of recurrent uveitis in horses from the southeastern United States

OBJECTIVE: To determine the role of intraocular bacteria in the pathogenesis of equine recurrent uveitis (ERU) in horses from the southeastern United States by evaluating affected eyes of horses with ERU for bacterial DNA and intraocular production of antibodies against Leptospira spp. SAMPLE POPULATION: Aqueous humor, vitreous humor, and serum samples of 24 clinically normal horses, 52 horses with ERU, and 17 horses with ocular inflammation not associated with ERU (ie, non-ERU inflammation). PROCEDURES: Ribosomal RNA quantitative PCR (real-time PCR) assay was used to detect bacterial DNA in aqueous humor and vitreous humor from clinically normal horses (n = 12) and horses with chronic (> 3-month) ERU (28). Aqueous humor and serum were also evaluated for anti-Leptospira antibody titers from clinically normal horses (n = 12), horses with non-ERU inflammation (17), and horses with confirmed chronic ERU (24). RESULTS: Bacterial DNA was not detected in aqueous humor or vitreous humor of horses with ERU or clinically normal horses. No significant difference was found in titers of anti-Leptospira antibodies in serum or aqueous humor among these 3 groups. Only 2 horses, 1 horse with ERU and 1 horse with non-ERU inflammation, had definitive intraocular production of antibodies against Leptospira organisms. CONCLUSIONS AND CLINICAL RELEVANCE: In horses from the southeastern United States, Leptospira organisms may have helped initiate ERU in some, but the continued presence of the organisms did not play a direct role in the pathogenesis of this recurrent disease.     

Indirect connectivity estimates of amphibian breeding wetlands from spatially explicit occupancy models

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Neutrophilic leucocytosis in a dog with a rectal tumour

A nine-year-old cocker spaniel was presented with a three-year history of intermittent haematochezia and a palpable rectal mass. Routine haematological examination revealed a marked mature neutrophilia (86.04 x 10(9) neutrophils/litre). A friable mass in the middle portion of the rectum was detected on colonoscopy. Histopathological examination of mucosal pinch biopsies collected from the mass confirmed a diagnosis of adenomatous tubulopapillary polyp. Some evidence of malignant transformation was observed. Palliative treatment with piroxicam suppositories at a dose of 1.4 mg/kg administered rectally every third day was instituted. On re-evaluation, 47 days after starting medical therapy, the owner reported a significant reduction in haematochezia and tenesmus; however, frequency of defecation had remained unaltered. Routine haematology revealed a reduction in the mature neutrophil count (33.67 x 10(9) neutrophils/litre). This report describes a case of a rectal tumour associated with a neutrophilic leucocytosis, which responded to palliative therapy with piroxicam suppositories.