Phenotypic stability of resistance to late blight in potato clones evaluated at eight sites in the United States

Changes in the fungal pathogenPhytophthora infestans in the United States pose a significant threat to potato production. Sources of resistance to these new genotypes of P.infestans need to be identified for potato breeders to have parental materials for crossing, and the phenotypic stability of late blight resistance in these potato clones needs to be determined. Sixteen potato clones which reportedly have some resistance to late blight were evaluated at eight locations: Florida (FL), Maine (ME), Michigan (MI), Minnesota (MN), North Dakota (ND), New York (NY), Pennsylvania (PA) and Wisconsin (WI) in 1996. Percent infected foliage was recorded at approximately weekly intervals following the onset of the disease at each location. Area under the disease progress curve (AUDPC) was calculated. Clones were ranked for mean AUDPC within location and the nonparametric stability statistics, mean absolute rank differences and variance of the ranks, were analyzed for phenotypic stability. Neither of these statistics was significant, indicating a lack of genotype x environment interaction on the rankings of these clones across locations in 1996. The four clones with lowest AUDPC scores were U.S. clones AWN86514-2, B0692-4, B0718-3 and B0767-2. These clones should be useful parental materials for breeders seeking to incorporate genes for late blight resistance into potatoes.     

Fracture associated sarcoma in the cat

A nine-year-old neutered male cat developed an osteosarcoma 15 months after the surgical repair of the proximal femur using an intramedullary pin at the fracture site. The repair had been effective with good healing of the fracture and restoration of normal activity.     

A toxicity study of low‐dose rate half‐body irradiation and chemotherapy in dogs with lymphoma

Thirteen dogs with previously untreated multicentric lymphoma were enrolled in a prospective study investigating the effects of low‐dose rate total body irradiation (TBI) and chemotherapy. Dogs received either 6 or 8 Gy TBI in half‐body fractions, 2 weeks apart. Toxicity consisted of mild to moderate haematological and gastrointestinal (GI) signs. One dog died from treatment complications. Anorexia was noted independent of dose. Haematological toxicity was more common and more severe after 8 Gy treatment. GI toxicity was more likely postcaudal half‐body irradiation with 8 Gy. Other than leukotrichia, late effects from radiation were not observed. Results indicated that haematological and nonhaematological toxicity was dose dependent. However, the protocol was well tolerated and treatment intensification using a 2‐week inter‐radiation interval was possible in all dogs treated with 6 Gy. Preliminary survival data for these dogs were very encouraging, providing a strong rationale to analyse the efficacy of low‐dose rate irradiation (LDRI) in canine lymphoma.     

Effects of time, initial composition, and stabilizing agents on the results of canine cerebrospinal fluid analysis

BACKGROUND: Cerebrospinal fluid (CSF) is considered highly labile, but not all samples are analyzed immediately. Changes in the composition of CSF could potentially affect diagnostic test results and thus influence decisions about patient management. There has been little scientific inquiry into how variables such as time, initial composition, and storage conditions affect results of standard laboratory analysis of CSF. OBJECTIVES: The objectives of this study were to determine the effects of time, protein concentration, and presence or absence of exogenous stabilizing agents on standard CSF analysis results. METHODS: Thirty abnormal CSF samples from 26 dogs were evaluated. Samples were divided into aliquots comprising different treatment groups and stored at 4 degrees C. Total nucleated cell count (TNCC), differential cell count (DCC), and cell morphology were evaluated for all groups; protein concentration was measured for selected groups. Unaltered aliquots were analyzed immediately (T0Hr) and at 2, 4, 8, 12, 24, and 48 hours (T2Hr-T48Hr); aliquots with added fetal calf serum (FCS) or hydroxyethyl starch (hetastarch) were analyzed at T48Hr. RESULTS: Significant time-dependent changes were observed in DCC in unaltered samples. Mononuclear cells deteriorated more rapidly than did neutrophils. Based on microscopic examination and subjective scoring of cell morphology, cells were consistently more degenerate by T24Hr compared with T0Hr. Samples with protein concentrations > or =50 mg/dL were less susceptible to cell deterioration than those with lower protein concentrations. Adding either FCS or hetastarch improved sample stability. CONCLUSIONS: Delayed analysis of canine CSF by 4-8 hours is unlikely to alter diagnostic interpretation, especially for samples with protein concentrations > or =50 mg/dL. The likelihood of misinterpretation is higher for samples with low cellularity or low protein concentration. We provide specific recommendations for adding FCS or hetastarch to samples that will not be analyzed within 1 hour.     

Components of small urban parks that predict the possibility for restoration

In densifying cities, small green spaces such as pocket parks are likely to become more important as settings for restoration. Well-designed small parks may serve restoration well, but earlier research on restorative environments does not provide detailed information about the specific components of the physical environment that support restoration. In this study we assessed the extent to which hardscape, grass, lower ground vegetation, flowering plants, bushes, trees, water, and size predicted the judged possibility for restoration in small urban green spaces. We took individual parks as the units of analysis. The parks were sampled from Scandinavian cities, and each park was represented by a single photo. Each photo was quantified in terms of the different objective park components and also rated on psychological variables related to restoration. The ratings on the psychological variables being away, fascination, likelihood of restoration, and preference were provided by groups of people familiar with such parks. The variables most predictive of the likelihood of restoration were the percentage of ground surface covered by grass, the amount of trees and bushes visible from the given viewing point, and apparent park size. Formal mediation analyses indicated distinctive patterns of full and partial mediation of the relations between environmental components and restoration likelihood by being away and fascination. Our results provide guidance for the design of small yet restorative urban parks.     

Hepatosplenic lymphoma in a dog

We describe a case of a dog with hepatosplenic lymphoma, a disease characterized by infiltration of the liver, spleen, and bone marrow with gammadelta T cells, absence of peripheral lymphadenopathy, and an aggressive clinical course. Physical examination findings, hematologic and biochemical abnormalities, and clinical course of the disease in this patient were similar to those in humans. Immunophenotyping of liver and spleen aspirates supported an antemortem diagnosis of T-cell lymphoma consistent with hepatosplenic lymphoma. The diagnosis was confirmed postmortem by a combination of routine histopathology, showing a consistent pattern of organ involvement, and immunohistochemistry showing the infiltrating neoplastic lymphocytes to be T cells expressing the gammadelta T-cell receptor. To our knowledge, this is the first reported case of hepatosplenic lymphoma in a dog.     

Changes in specific virulence in Polish populations ofPhytophthora infestans: 1985–1991

Ninety-five isolates ofPhytophthora infestans collected throughout Poland during 1985–1991 and characterized for multilocus genotypes based on mating type, allozymes and DNA fingerprint, were analyzed for specific virulence to differential potato cultivars carrying ten major resistance genes. The multilocus analysis led to three groupings. The first group contained 22 isolates of a clonal lineage (PO-1) that is postulated to have been present in Europe during most of the twentieth century, but PO-1 isolates were recovered in Poland only during 1985–1988. This group contained, on average, virulence to 5.5 specific resistance genes per isolate. The second group consisted of 30 isolates in a clonal lineage (PO-4) that had not been detected before 1988. PO-4 isolates had virulence to a mean of 6.5 resistance genes per isolate. The third group was composed of 43 isolates representing 38 multilocus genotypes also not detected before 1988. These diverse genotypes had virulence to an average of 6.7 specific resistance genes per isolate. More than half (53%) of the PO-4 isolates shared a single pathotype. The group of 43 isolates was dominated by two pathotypes: the most common one (47% of the isolates) was the same pathotype that dominated PO-4 isolates; the next most common one (21%) differed from the most common one by the absence of virulence to resistance gene R5. The recent immigrant isolates (not detected before 1988) generally had virulence to a greater number of specific resistance genes than did isolates in the previous population [detected before 1988 (PO-1)]. Recent immigrant populations were dominated by one or two pathotypes, so their pathotypic diversity values were somewhat less than that of the previous population.     

Sensitivity to Protectant Fungicides and Pathogenic Fitness of Clonal Lineages of Phytophthora infestans in the United States

ABSTRACT Since 1991, dramatic changes have occurred in the genetic composition of populations of Phytophthora infestans in the United States. Clonal lineages recently introduced into the United States (US-7 and US-8) are more common now than the previously dominant lineage (US-1). To help determine why these changes occurred, four clonal lineages of P. in-festans common during the early 1990s in the United States and Canada were evaluated for sensitivity to the protectant fungicides mancozeb and chlorothalonil using amended agar assays for isolates collected from 1990 to 1994. No isolate or lineage was resistant to either mancozeb or chlorothalonil. There were significant differences among isolates for degree of sensitivity to one fungicide individually, but there were no significant (P = 0.05) differences among the US-1, US-6, US-7, and US-8 clonal lineages for degree of sensitivity to both fungicides. Therefore, resistance to protectant fungicides cannot explain the rapid increase in frequency of the US-7 and US-8 clonal lineages. Three components of pathogenic fitness (latent period, lesion area, and sporulation after 96 h) were tested for the three clonal lineages that were detected most commonly during 1994 (US-1, US-7, and US-8). All but one of the isolates in this analysis were collected during 1994 and evaluated within 10 months of collection by inoculating detached leaflets of the susceptible potato cultivar Norchip. There were significant differences between the US-1 and US-8 clonal lineages for lesion area and sporulation, and between US-1 and US-7 for latent period. The US-6 clonal lineage was excluded from the pathogenic fitness experiments, because no isolates of this lineage were collected during 1994. Compared with US-7 and US-8, US-1 had the longest latent period and the smallest lesions with the least sporulation. Incorporation of the differences between US-1 and US-8 in computer simulation experiments revealed that significantly more protectant fungicide (e.g., 25%) would be required to suppress epidemics caused by the US-8 clonal lineage compared with US-1. These differences in pathogenic fitness components probably contribute to the general predominance of the "new" clonal lineages (especially US-8) relative to the "old" US-1 lineage.