Cohort‐specific variation in juvenile coho salmon habitat use

In this study, we examined summer and fall freshwater rearing habitat use by juvenile coho salmon (Oncorhynchus kisutch) in the quickly urbanising Big Lake drainage in south‐central Alaska. Habitat use was assessed by regressing fish count data against habitat survey information across thirty study sites using generalised linear mixed models. Habitat associations were examined by age‐0 and age‐1+ cohorts separately, providing an opportunity to compare habitat use across different juvenile coho salmon life stages during freshwater rearing. Regression results indicated that the age‐0 cohorts were strongly associated with shallow, wide stream reaches with in‐stream vegetation, whereas age‐1+ cohorts were associated with deeper stream reaches. Furthermore, associations between fork length and habitat characteristics suggest cohort‐specific habitat use patterns are distinct from those attributable to fish size. Habitat use information generated from this study is being used to guide optimal fish passage restoration planning in the Big Lake drainage. Evidence for habitat use partitioning by age cohort during freshwater juvenile rearing indicates that pooling age cohorts into a single “juvenile” stage for the purposes of watershed management may mask important habitat use dynamics.     

Coccidioidomycosis in 48 Cats: A Retrospective Study (1984–1993)

Coccidioidomycosis was diagnosed in 48 cats. Forty-one cases were identified within a period of 3 years. Coccidioides immitis was revealed by cytological or histopathological examinations, or culture in 70% of cats. The remaining 30% of cases were diagnosed by appropriate clinical signs, radiographic lesions, and serological test results. The average age of affected cats was 6.2 years with a median age of 5.0 years. Fifty-four percent (n = 26) were female and 46% (n = 22) were male. Domestic shorthaired and longhaired breeds comprised 89% (n = 41) of affected cats. Sixty-seven percent of cases were diagnosed during the 6-month period of December through May. Cats infected with C immitis were presented for evaluation of dermatologic (56%), respiratory (25%), musculoskeletal (19%), and neurological or ophthalmologic signs (19%). Fever, inappetence, and weight loss were present in 44% of the cats. Duration of clinical signs before diagnosis was less than 4 weeks in 85% (n = 42) of cats, with an average of 3.8 weeks and a median of 2 weeks. Agar gel immunodiffusion tests were positive in all 39 cats tested at sometime during the course of their disease. Hyperproteinemia (greater than 7.9 g/dL) was present in 52% (10/23) of cases. The majority of cats (n = 39) were negative for feline leukemia virus. Antibodies to feline immunodeficiency virus were absent in the 19 cats tested. Ketoconazole was the most common antifungal agent used to treat cats with Coccidioidomycosis. Duration of treatment ranged from less than 1 week to 43 months. Thirty-two cats are currently asymptomatic, with or without treatment. Eleven cats died or were euthanized. Five cats were lost to follow-up. Ketoconazole likely is more suppressive than curative because relapses were common after discontinuing therapy.     

"Dog pox": some clinical aspects of an eruptive condition of certain mucous surfaces in dogs.

An eruptive condition seen on certain mucous membranes of dogs occurs frequently but often asymptomatically. Lesions have been found to be present in over 60 percent of male dogs. The infection is probably due to a canine herpes virus and has been termed conveniently but inaccurately "dog pox". In many cases lesions are present without observable clinical signs but severe irritation, especially related to lesions in the lower bowel, can give rise to marked symptoms which may be confused with abnormality of the para-anal sacs, or to chronic diarrhoea of a type suggestive of colitis. The incidence, sites of infection and possible syndromes which may be ascribed to the condition are briefly discussed on a clinical basis only.     

Landscape patterns as habitat predictors: building and testing models for cavity-nesting birds in the Uinta Mountains of Utah,USA

The ability to predict species occurrences quickly is often crucial for managers and conservation biologists with limited time and funds. We used measured associations with landscape patterns to build accurate predictive habitat models that were quickly and easily applied (i.e., required no additional data collection in the field to make predictions). We used classification trees (a nonparametric alternative to discriminant function analysis, logistic regression, and other generalized linear models) to model nesting habitat of red-naped sapsuckers (Sphyrapicus nuchalis), northern flickers (Colaptes auratus),tree swallows (Tachycineta bicolor), and mountain chickadees (Parus gambeli) in the Uinta Mountains of northeastern Utah, USA. We then tested the predictive capability of the models with independent data collected in the field the following year. The models built for the northern flicker, red-naped sapsucker, and tree swallow were relatively accurate (84%, 80%, and 75% nests correctly classified,respectively)compared to the models for the mountain chickadee (50% nests correctly classified). All four models were more selective than a null model that predicted habitat based solely on a gross association with aspen forests. We conclude that associations with landscape patterns can be used to build relatively accurate, easy to use, predictive models for some species. Our results stress, however, that both selecting the proper scale at which to assess landscape associations and empirically testing the models derived from those associations are crucial for building useful predictive models. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synergistic and antagonistic effects of atrazine on the toxicity of organophosphorodithioate and organophosphorothioate insecticides to Chironomus tentans (Diptera: Chironomidae)

The acute toxicities of two organophosphorodithioate (dimethoate and disulfoton) and two organophosphorothioate (omethoate and demeton-S-methyl) insecticides were evaluated individually and in binary combination with the herbicide atrazine using fourth-instar larvae of the aquatic midge, Chironomus tentans. Atrazine alone up to 1000 μg/L did not show significant toxicity to the midges in a 48-h bioassay. However, atrazine concentrations as low as 1 μg/L in combination with dimethoate at EC₂₅ (concentration to affect 25% of tested midges), 100 μg/L in combination with disulfoton (EC₂₅), and 10 μg/L in combination with demeton-S-methyl (EC₂₅) significantly enhanced the toxicity of each organophosphate insecticide. In contrast, atrazine concentrations of 10 μg/L and above in combination with omethoate (EC₂₅) significantly decreased the toxicity of the insecticide. Biochemical analysis indicated that increased toxicity of dimethoate, disulfoton, and demeton-S-methyl in binary combination with atrazine correlated to the increased inhibition of acetylcholinesterase. Furthermore, cytochrome P450-dependent O-deethylation activity in the midges exposed to atrazine at 1000 μg/L was 1.5-fold higher than that in the control midges. Thus, atrazine appeared to induce cytochrome P450 monooxygenases in the midges. Elevated cytochrome P450 monooxygenase activity may increase the toxicities of dimethoate, disulfoton, and demeton-S-methyl by enhancing the oxidative activation of dimethoate into omethoate, and disulfoton and demeton-S-methyl into their sulfoxide analogs with increased anticholinesterase activity. In contrast, atrazine reduced the toxicity of omethoate possibly by enhancing the oxidative metabolic detoxification since omethoate does not require oxidative activation.     

Analysis of pastoralists’ perception on challenges and opportunities for sheep and goat production in Northern Kenya

Tropical Animal Health and Production - Small ruminants’ production contributes to livelihood of pastoral communities, but this faces myriad constraints. This study aimed at identifying...     

Ace and ace-like genes of invasive redlegged earth mite: copy number variation,target-site mutations,and their associations with organophosphate insensitivity

Background

Invasive Australian populations of redlegged earth mite, Halotydeus destructor (Tucker), are evolving increasing organophosphate resistance. In addition to the canonical ace gene, the target gene of organophosphates, the H. destructor genome contains many radiated ace-like genes that vary in copy number and amino acid sequence. In this work, we characterise copy number and target-site mutation variation at the canonical ace and ace-like genes and test for potential associations with organophosphate insensitivity. This was achieved through comparisons of whole-genome pool-seq data from alive and dead mites following organophosphate exposure.

Results

A combination of increased copy number and target-site mutations at the canonical ace was associated with organophosphate insensitivity in H. destructor. Resistant populations were segregating for G119S, A201S, F331Y at the canonical ace. A subset of populations also had copy numbers of canonical ace > 2, which potentially helps overexpress proteins carrying these target-site mutations. Haplotypes possessing different copy numbers and target-site mutations of the canonical ace gene may be under selection across H. destructor populations. We also detected some evidence that increases in copy number of radiated ace-like genes are associated with organophosphate insensitivity, which might suggest potential roles in sequestration or breakdown of organophosphates.

Conclusion

Different combinations of target-site mutations and (or) copy number variation in the canonical ace and ace-like genes may provide non-convergent ways for H. destructor to respond to organophosphate selection. However, these changes may only play a partial role in organophosphate insensitivity, which appears to have a polygenic architecture. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.