Snow mould caused by a Pythium sp.: a potential vascular plant pathogen in the maritime Antarctic

The pathogenicity of an isolate of a Pythium species from Signy Island in the South Orkney Islands was tested against the Antarctic hairgrass Deschampsia antarctica. The isolate was found to infect plants at 8ºC and to cause foliar and root symptoms similar to those seen in other Pythium infections in grasses. Analysis of ribosomal RNA sequences placed it, together with another isolate from Antarctica, in a clade that included the known snow moulds caused by Pythium spp. Sporangia and oogonia were produced in culture, but the isolate differed from other Pythium spp. in producing chlamydospores in older cultures and plant tissue. This is the first report of a pathogen of an eukaryotic vascular plant in the maritime Antarctic region.     

Hematologic changes induced by intravenous administration of diacetoxyscirpenol in pigs, dogs, and calves

Diacetoxyscirpenol (DAS) was given IV to pigs (0, 0.5, and 1.0 mg/kg of body weight), cattle (0 and 0.5 mg/kg), and dogs (0 and 0.5 mg/kg). Blood was collected and hemograms were done at 0.5-hour intervals for 8 hours. The animals were euthanatized at 8 hours after treatment, and bone marrow samples were taken and examined by light microscopy. Moderate to severe necrosis of bone marrow hematopoietic elements was found in animals given DAS. The sequential increase in the type and number of abnormal cells in the blood suggested a successive destruction of the hematopoietic elements. A marked left shift in the neutrophil population was found in animals given DAS. Metarubricytes and large platelets were found in the blood of animals given DAS. Lymphocytes were replaced with immature cells. Pathologic changes were most severe in the pigs given a dosage of 1.0 mg of DAS/kg. The order of species sensitivity to DAS was pigs greater than dogs much greater than cattle.     

Occurrence of Mycobacterium avium subspecies paratuberculosis and Neospora caninum in Alberta cow-calf operations

Mycobacterium avium subsp. paratuberculosis (MAP) and Neospora caninum (NC) are two pathogens causing important production limiting diseases in the cattle industry. Significant impacts of MAP and NC have been reported on dairy cattle herds, but little is known about the importance, risk factors and transmission patterns in western Canadian cow-calf herds. In this cross-sectional study, the prevalence of MAP and NC infection in southwest Alberta cow-calf herds was estimated, risk factors for NC were identified, and the reproductive impacts of the two pathogens were assessed.     

Deterministic generation of single photons from one atom trapped in a cavity

A single cesium atom trapped within the mode of an optical cavity is used to generate single photons on demand. The photon wave packets are emitted as a Gaussian beam with temporal profile and repetition rate controlled by external driving fields. Each generation attempt is inferred to succeed with a probability near unity, whereas the efficiency for creating an unpolarized photon in the total cavity output is 0.69 +/- 0.10, as limited by passive cavity losses. An average of 1.4 x 10(4) photons are produced by each trapped atom. These results constitute an important step in quantum information science, for example, toward the realization of distributed quantum networking.     

Neuropathologic findings of bromethalin toxicosis in the cat.

Ten random source male domestic shorthair cats, 2 to 6 years old and 3.0-4.4 kg body weight, were each given a single oral dose (1.5 mg/kg) of bromethalin (cat Nos. 1-5) or bait vehicle carrier (cat Nos. 6-10). Bromethalin-dosed cats developed a toxic syndrome characterized by ataxia, focal motor seizures, vocalization, decerebrate posture, decreased conscious proprioception, recumbency, depression, and semicoma. Bromethalin-dosed cats were euthanatized if seizure activity or hindlimb paralysis developed. Survival times were 48 hours (cat No. 1), 89 hours (cat No. 2), 90 hours (cat No. 3), and 97 hours (cat No. 4). Control cats (cat Nos. 6-10) and one bromethalin-dosed cat (cat No. 5) were euthanatized on day 20 after dosing. Spongy change (edema--characterized by the formation of vacuoles in extracellular spaces and myelin lamellae), hypertrophied fibrous astrocytes, and hypertrophied oligodendrocytes were observed in the white matter of the cerebrum, cerebellum, brain stem, spinal cord, and optic nerve of all bromethalin-dosed cats. Spongy change occasionally extended into contiguous cerebellar Purkinje cell layer and cerebral cortical gray matter. The severity of lesions varied among cats but was most pronounced in cat No. 5 (480 hours after dosing). A leukocytic inflammatory response, gitter cell (macrophage) response, or axonal degeneration was not observed in the vacuolated areas. Ultrastructural findings included separation of myelin lamellae at the interperiod lines with the formation of intramyelinic vacuoles (intramyelinic edema), rupture and coalescence of intramyelinic vacuoles into larger extracellular spaces (spongy change), and pronounced cytosolic edema of astrocytes and oligodendroglial cells.