Publications

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patterns of trematode and nematode lungworm infections in northern leopard frogs and wood frogs from ontario, canada.in this study we examined trematode and nematode lung helminths commonly found in two species of host ranid frogs for competitive interactions. we examined 147 adult (breeding and non-breeding) and juvenile northern leopard frogs, and 84 breeding male wood frogs in bishops mills, ontario for haematoloechus spp. (trematoda) and rhabdias sp. (nematoda) infections. a strong negative association between phyla of helminth was observed in breeding and juvenile northern leopard frogs, and also in breed ...200919321016
five amphibian mortality events associated with ranavirus infection in south central ontario, canada.using field, molecular and histological methods, an epizootic, systemic disease causing death within wood frog rana sylvatica tadpoles and leopard frog rana pipiens metamorphs at 3 different locations within southern ontario, canada, has been investigated. our results demonstrated that the probable cause of this disease was a ranavirus. affected amphibians were found to exhibit necrosis within the hematopoietic cells. liver tissue samples were found positive for the virus by pcr amplification of ...200516385802
the life history and host specificity of hepatozoon clamatae (apicomplexa: adeleorina) and its-1 nucleotide sequence variation of hepatozoon species of frogs and mosquitoes from ontario.the life cycle of an intraerythrocytic hemogregarine, hepatozoon clamatae, was studied in green frogs (rana clamitans melanota), bullfrogs (rana catesbeiana), northern leopard frogs (rana pipiens), and in the mosquito, culex territans. gametogenesis, fertilization, and sporogony occurred within cells of the malpighian tubules of laboratory-reared cx. territans that had fed on naturally infected frogs. mature oocysts containing hundreds of sporocysts were observed in mosquitoes 30 days postfeedin ...19989714212
ultrastructural features of cystic and merogonic stages of hepatozoon sipedon (apicomplexa: adeleorina) in northern leopard frogs (rana pipiens) and northern water snakes (nerodia sipedon) from ontario, canada.the cystic and merogonic stages of the haemogregarine hepatozoon sipedon, infecting northern water snakes (nerodia sipedon sipedon) and northern leopard frogs (rana pipiens), respectively, in ontario, canada, were investigated by transmission electron microscopy. cysts, which were observed in the liver of northern leopard frogs (rana pipiens) after these anurans ingested mosquitoes (culex pipiens) containing oocysts of the parasite, harboured two cystozoites, each of which contained a large crys ...19989703677
the life history, ultrastructure, and experimental transmission of hepatozoon catesbianae n. comb., an apicomplexan parasite of the bullfrog, rana catesbeiana and the mosquito, culex territans in algonquin park, ontario.gametogenesis and sporogonic development of a haemogregarine parasite of bullfrogs (rana catesbeiana) was observed in cells of the malpighian tubules of laboratory-reared culex territans that had fed on naturally infected bullfrogs. mature oocysts, which varied considerably in size, were multisporocystic with ellipsoidal sporocysts that contained 4 sporozoites. sporogonic development was completed in about 20 days. mature meronts were observed in the liver and merozoites in erythrocytes of labor ...19957707196
observations on the seasonal prevalence, pathology and transmission of dracunculus insignis (nematoda: dracunculoidea) in the raccoon (procyon lotor (l.) in ontario.lesions due to dracunculus insignis in the legs of raccoons (procyon lotor) in southern ontario occur seasonally as most larvigerous females emerge in the spring and early summer (april-june). the pathology of dracunculiasis in the raccoon is described and the transmission of the parasite in the wild is discussed with respect to seasonality and local agricultural practices. crayfish, fishes and frogs (including tadpoles) were given infective third-stage larvae of d. insignis to test their suitab ...1977144196
potential endocrine disruption of sexual development in free ranging male northern leopard frogs (rana pipiens) and green frogs (rana clamitans) from areas of intensive row crop agriculture.intensive row crop agriculture (irca) for corn and soybean production is predominant in eastern and central north america. irca relies heavily on pesticide and nutrient inputs to maximize production under conventional systems. in 2003-2005, we assessed the occurrence of a suite of potential endocrine effects in amphibians inhabiting farm ponds and agricultural drains in irca areas of southwestern ontario. effects were compared to amphibians from two agricultural reference sites as well as four n ...200818582957
effect of release herbicide on mortality, avoidance response, and growth of amphibian larvae in two forest wetlands.effects of release herbicide (triclopyr butoxyethyl ester, [tbee]) on mortality, avoidance response, and growth of larval amphibians (rana clamitans, rana pipiens) were investigated using in situ enclosures deployed in two forest wetlands in northern ontario, canada. release was applied at nominal concentrations ranging from 0.26 to 7.68 mg tbee acid equivalents (ae)/l. no significant deleterious effects of this herbicide on larval growth were detected. however, concentration-dependent mortality ...200516268155
chemical and biomonitoring to assess potential acute effects of vision herbicide on native amphibian larvae in forest wetlands.in conjunction with operational forest herbicide spray programs in ontario, canada, chemical and biological monitoring studies were conducted in 51 different wetlands to quantify the probability and magnitude of contamination by a glyphosate herbicide formulation (vision). wetlands were classified as oversprayed, adjacent, or buffered in relation to the operational target spray blocks. results show that vegetated buffers significantly mitigated against exposure and thus potential for acute effec ...200415095878
genotoxicity monitoring of small bodies of water using two species of tadpoles and the alkaline single cell gel (comet) assay.to monitor genotoxicity in small bodies of water (e.g., creeks, ponds, and drainage ditches) we examined tadpole erythrocytes of two species: rana clamitans and rana pipiens,using the alkaline single cell gel dna electrophoresis (scg) or "comet" assay. this approach involves detection, under alkaline conditions, of cell dna fragments which on electrophoresis migrate from the nuclear core, resulting in a "comet with tail" formation. fifty-six samples, a total of 606 tadpoles, from 18 sites in sou ...19979212794
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