Canine choroidal melanoma with metastases

A 3-year-old-female, spayed Golden Retriever was examined for a unilateral retinal detachment with exophthalmos. Ultrasonographically, a mass was detected with intra- and extraocular extension. The orbit was exenterated and the dog recovered uneventfully. Histopathologic diagnosis was a primary choroidal melanoma with orbital extension, however, the behavioral and cytologic features were benign. Routine examinations postsurgically were nonremarkable. Twenty-one months after surgery the dog was euthanized for respiratory collapse with radiographic signs of metastasis. Necropsy revealed black lesions in the lung and liver. Histopathologic diagnosis was metastatic melanoma with morphology and behavior identical to the primary choroidal melanoma. This is the first definitive case of a canine choroidal melanoma with metastasis.     

Population changes in Phytophthora infestans in Taiwan associated with the appearance of resistance to metalaxyl

In recent years, late blight, caused by Phytophthora infestans (Mont) De Bary, has increased in severity in many parts of the world, and this has been associated with migrations which have introduced new, arguably more aggressive, populations of the pathogen. In Taiwan, late blight has been endemic on outdoor tomato crops grown in the highlands since the early 1900s, but recent epidemics have been more damaging. To ascertain the present status of the Taiwanese population of P infestans, 139 isolates of the pathogen collected and maintained by the Asian Vegetable Research and Development Center (AVRDC) were characterized using mating type, metalaxyl sensitivity, allozyme genotype, mitochondrial haplotype and RFLP fingerprinting. Up to 1997, all isolates were found to belong to the old clonal lineage of P infestans (US-1 and variants), but in isolates from 1998 a new genotype appeared, and by 2000 this had apparently completely displaced the old population. This new genotype was an A1 mating type and has the dilocus allozyme genotype 100/100/111, 100/100 for the loci coding for glucose-6-phosphate isomerase and peptidase, respectively. These characters, together with RG57 fingerprinting, indicated that these isolates belonged to the US-11 clonal lineage, a minority (11%) being a previously unreported variant of US-11. Whereas metalaxyl-resistant isolates were not detected in the old population, 96% of the new genotypes proved resistant, with the remainder being intermediate in sensitivity. It may be inferred from this sudden, marked change in the characteristics of the Taiwanese P infestans that a new population of the pathogen was introduced around 1997-98 and that this may well have already been metalaxyl-resistant when it arrived, although a role for in situ selection cannot be excluded.     

Use of sentinel chickens to evaluate the effectiveness of cleaning and disinfection procedures in noncommercial poultry operations infected with exotic Newcastle disease virus.

The use of sentinel chickens in establishing the negative status of commercial poultry flocks depopulated due to exotic Newcastle disease (END) is considered to be an economically beneficial process. However, the costs and benefits of using sentinel chickens in noncommercial operations are in question. The objective of this study was to use sentinel chickens to evaluate whether adequate cleaning and disinfection coupled with an appropriate time period without susceptible poultry species on the premises would eliminate END virus from a noncommercial poultry operation and preclude the need for placement of sentinels in previously infected operations before declaring them free of virus. Noncommercial poultry operations were selected from the 2002 to 2003 END outbreak database. Operations included in the study had one or more isolations of END virus (ENDV) from cloacal or oropharyngeal swabs of birds on the premises. A total of 546 birds were placed on 53 premises. All sentinel birds sampled after placements were negative by virus detection methods and serologic tests. Results of this study indicate that time and the application of appropriate cleaning and disinfection procedures will adequately mitigate the risk of viable virus persisting in noncommercial poultry operations. In the future, this information may eliminate the need for sentinel bird placement to ensure virus free status of premises before repopulation, thereby decreasing the costs of END eradication.     

African spider flower (Cleome gynandra L./Gynandropsis gynandra (L.) Briq.) as a red spider mite (Tetranychus urticae Koch) repellent in cut-flower rose (Rosa hybrida L.) cultivation

Companion planting of Cleome gynandra, of Kenyan origin, in beds of cut-flower roses reduces significantly red spider mite (Tetranychus urticae Koch) infestation without any detrimental effect on productivity or flower quality. The level of reduction is dependent upon the density of the C. gynandra plants with 15 plants in a 1.8 m² bed (8.3 plants m²) being the most effective, planted either around the bed perimeter or within the rows of roses. The relatively high density of C. gynandra plants required may limit the direct application of this technology in export-focused, greenhouse rose production yet may be of significant value as a supplement to other mite-control strategies. The potential benefits of such companion planting for growers of field roses and those involved in some domestic markets are also evident. Research into the nature and extraction of the active, volatile mite-repellant components of C. gynandra is indicated.     

The Knockdown Resistance (kdr) Mutation in Pyrethroid-Resistant German Cockroaches

A point mutation in thepara-homologous sodium channel gene has been shown to be associated with knockdown resistance (kdr) in several insect species including the German cockroach. In this study, we analyzed the genomic organization of the region where thekdrmutation resides and then performed polymerase chain reaction (PCR) and sequencing using genomic DNA as the template to detectkdrmutation in 24 pyrethroid-resistant German cockroach strains, most of which have been collected recently from the field. Thekdrmutation, G to C at nt 2979 resulting in a leucine to phenylalanine amino acid substitution, was detected in 20 strains including 2 strains from overseas (China and Germany). Our results clearly indicate that thekdrmutation is widespread in German cockroach populations. However, the super-kdrmutation detected in super-kdrhouse flies was not found in any of the 4 strains that showed higher levels of knockdown resistance. Little correlation was observed between the presence of thekdrmutation and the level of knockdown resistance, suggesting the existence of multiple resistance mechanisms in many of these strains.     

Economic Impact of Double‐Crested Cormorant,Phalacrocorax auritus,Depredation on Channel Catfish,Ictalurus punctatus,Aquaculture in Mississippi,USA

The Yazoo River Basin of Mississippi, USA, supports the largest concentration of hectares devoted to channel catfish, Ictalurus punctatus, aquaculture production in North America. The Yazoo Basin also supports large numbers of resident, wintering and migrating fish‐eating birds, with the Double‐crested Cormorant, Phalacrocorax auritus, implicated as the most serious depredating species. We used data from aerial surveys of numbers and distribution of cormorants in the Yazoo Basin and on commercial catfish ponds during winters (November–April) 2000–2001 and 2003–2004 to refine estimates of regional economic losses due to cormorant depredation. In both periods, the greatest monthly estimates of cormorant foraging occurred from 1 January to 31 March. Losses in terms of biomass, number, and dollar value were greater for foodfish ponds than fingerling ponds. Monthly weighted estimates of catfish consumed were 1775.3 and 1346.6 m.t. over winters 2000–2001 and 2003–2004, respectively. Total estimated losses for foodfish and fingerling ponds in 2000–2001 were $11.56 and $0.48 million, respectively, and in 2003–2004 were $5.22 and $0.40 million, respectively. Maximum dollar loss occurred during March in 2000–2001 and during February in 2003–2004. In this study, the volatility in variable production costs and nominal sales price, and distribution of cormorants on pond types and regionally were key factors in resulting economic loss estimates.     

Heterotrophic N2-fixation in arid soil crusts

The cryptogamic soil crusts of the Great Basin Artemisia, Ceratoides, and Atriplex plant communities contain a significant heterotrophic N₂-fixing microbial population in addition to the predominating filamentous cyanobacteria. The bacterial association with the cyanobacteria exhibits a phycosphere-like effect. Heterotrophically fixed N gains reached 17.5 μg N· g^?1 of soil (23.1% increase above the initial soil N content) and 45.9 μg N·g^?1 of soil (57.4% increase) after 3 and 5 weeks, respectively. (NH₄)₂SO₄ and native plant material amendments to soil resulted in a 41–100% reduction in N₂-fixation. The potential input of N to soil crusts may be reduced in the presence of shrub-produced allelochemic agents and by concurrent denitrification.