Predation dynamics of mackerel on larval and juvenile anchovy: is capture success linked to prey condition?

We tested whether the predation dynamics of chub mackerel Scomber japonicus and spotted mackerel S. australasicus on young anchovy Engraulis japonicus relates to individual growth characteristics of the prey and could account for the growth-selective survival predicted by recruitment hypotheses. Juvenile and adult mackerel were sampled along with their young anchovy prey field in 2004 (juvenile mackerel and larval anchovy) and 2005 (adult mackerel and juvenile anchovy) off the Pacific coast of Honshu, Japan. The recent 5-day mean growth rate of larval and juvenile survivors and prey found in the stomach of mackerel was estimated from the otolith microstructure. No significant difference was found between the recent growth of larval or juvenile survivors and that of preyed individuals. We conclude that despite a relatively small body size, the high activity level and predation skills displayed by mackerel prevent fast-growing larvae and early juveniles from benefitting in terms of the expected survival advantage over slow-growers. Hence, growth-selective predation mortality of larval fish would depend on the feeding ecology of the predator rather than predator size. Selection for fast growth is more likely to occur under predation pressure from invertebrate organisms and small pelagic fish specialized on zooplankton, such as herring and anchovy.     

中华蜜蜂幼虫信息素鉴定

 【目的】分析鉴定中华蜜蜂(Apis cerana cerana)幼虫是否含有与西方蜜蜂（Apis mellifera）幼虫相同的幼虫利它素和信息素及其在不同日龄阶段幼虫的分布情况。【方法】以中华蜜蜂为试验材料,取2日龄、6日龄（即将封盖）和7日龄（封盖后）的工蜂幼虫及2日龄、7日龄（即将封盖）和8日龄（封盖后）的雄蜂幼虫,经过正己烷浸泡碾碎,取上清液并进行层析过柱分离,应用气相色谱来研究中华蜜蜂幼虫利它素和信息素。【结果】本研究首次发现中华蜜蜂幼虫信息素含有甲基棕榈酸酯（MP）、甲基油酸酯(（MO）、甲基硬脂酸酯（MS）、甲基亚油酸酯（ML）、甲基亚麻酸酯（MN）、乙基棕榈酸酯（EP）、乙基油酸酯（EO）、乙基硬脂酸酯（ES）、乙基亚油酸酯（EL）和乙基亚麻酸酯（EN）。【结论】中华蜜蜂幼虫含有与西方蜜蜂幼虫相同的幼虫利它素和10种脂肪类信息素,但这两种蜜蜂信息素的含量及在不同日龄幼虫分布规律不同。     

Microbial activities during the early stage of laboratory decomposition of tropical leaf litters: the effect of interactions between litter quality and exogenous inorganic nitrogen

The comparative decomposition of tropical leaf litters (e.g. Andropogon gayanus, Casuarina equisetifolia, Faidherbia albida) of different qualities was investigated under laboratory conditions during a 60-day incubation period conducted with a typical oxisol. Total CO₂-C, soil inorganic N, microbial biomass (fumigation-extraction), -glucosidase and dehydrogenase activities were determined over the incubation to assess how they responded to the addition of inorganic N (+N). Cumulative CO₂-C evolved from the litter-amended soils was higher than that recorded for the unamended control soil. For the unfertilized treatment (0 N), correlation coefficients calculated between initial chemical data and CO₂ flux during the first day of incubation were r =0.963 for water soluble-C and 0.869 for soluble carbohydrates (P <0.05). At the end of the incubation, the amounts of CO₂-C in the F. albida- and A. gayanus-amended soils were higher than that in the C. equisetifolia-amended treatment. Cumulative net N immobilization increased during the first 30 days of incubation, the amounts being similar for A. gayanus- and C. equisetifolia-amended soil and higher than that recorded in the F. albida-amended treatment. Soil microbial biomass and enzyme activities increased in the litter-amended soils during the first 15 days of incubation and decreased (except for the dehydrogenase activity) thereafter. The addition of inorganic N modified the patterns of CO₂-C respiration and net N immobilization. The magnitude of these modifications varied according to the litter quality. The use of an accurate indicator based on several litter components to predict the amplitude of organic material decomposition is discussed.     

Distribution of equine infectious anemia in horses in the north of Minas Gerais State, Brazil.

The paper examines the prevalence of equine infectious anemia (EIA) in horse populations in the northern part (comprising 89 cities) of Minas Gerais State, Brazil, from January 2002 to December 2004. Data on 8,981 agar gel immunodiffusion test results from the region were used as input for a statistical and autoregressive analysis model to construct a city-level map of the distribution of EIA prevalence. The following EIA prevalence (P) levels were found: 49 cities with 0 < P < or = 0.5%, 26 with 0.5% < P < or = 1.5%, 10 with 1.5% < P < or = 5%, and 4 with 5% < P < or = 25%.     

Palliative intracavitary carboplatin therapy in a cat with suspected pleural mesothelioma

A 12-year-old neutered male oriental shorthair cat was referred to the Animal Health Trust for investigation of pleural effusion. Ultrasonography revealed marked irregular thickening of the pleural surface of the cranial and caudal mediastinum. Cytological examination of the pleural fluid and fine needle aspirates of the thickened pleura suggested a diagnosis of mesothelioma. Following complete drainage of the thoracic cavity under ultrasound guidance, 180 mg/m2 carboplatin diluted in 60 ml sterile water was infused into the pleural space (30 ml in each hemithorax). This resulted in complete resolution of clinical signs for 34 days (having required thoracocentesis on four occasions in the preceding 4 weeks). The procedure was repeated using 200 mg/m2 carboplatin, and there was a further 20-day period where the cat was free of clinical signs. Further treatment was declined and the cat was euthanased 120 days after initial presentation. This is the first report of successful palliative chemotherapy for suspected feline mesothelioma and suggests that intracavitary carboplatin could be considered in tumours affecting the pleural cavity.     

Diagnostic potential of natriuretic peptides in the occult phase of golden retriever muscular dystrophy cardiomyopathy

The objective of the study was to determine whether the plasma concentrations of atrial and brain natriuretic peptides (ANP and BNP, respectively) could be reliable markers of cardiac alterations during occult cardiomyopathy in Golden Retriever Muscular Dystrophy (GRMD). Fifty Golden Retrievers without any clinical or radiographic sign of heart disease were included in this study (21 GRMD dogs and 29 controls). Controls and GRMD dogs were divided into 2 subgroups according to age (< and > or =12 months old, respectively). All dogs underwent echocardiography and determination of BNP and ANP plasma concentrations by radioimmunoassay. No ventricular dilatation or dysfunction was observed in either control or GRMD dogs. ANP plasma concentration did not differ significantly between controls and GRMD dogs (mean +/- SD = 72 +/- 49 versus 58 +/- 23 pg/mL, respectively, P = .21). This finding was confirmed in both subgroups of dogs (ie, those < and > or =12 months old). In contrast, BNP plasma concentrations were significantly higher in GRMD dogs than in controls (mean +/- SD = 117 +/- 92 versus 46 +/- 22 pg/mL, respectively, P < .05). In dogs > or =12 months old, sensitivity and specificity of BNP for identifying GRMD with a cutoff of 65 pg/mL were 78 and 86%, respectively. For the same cutoff value, sensitivity dropped to 42%, whereas specificity reached 100% in dogs <12 months old. In conclusion, BNP may be a useful biochemical marker of asymptomatic cardiomyopathy. However, this peptide does not allow very early detection because its optimal discriminatory power was observed in adult dogs (ie, > or =12 months of age).     

Site fidelity and movements of an amphidromous goby revealed by otolith multi‐elemental signatures along a tropical watershed

Otolith microchemistry can provide crucial information to address gaps of knowledge in spatio‐temporal ecology of fish species. However, understanding the seasonal variability of water chemistry and its effect on otolith signatures is needed to interpret fish movements. Otolith multi‐elemental signatures were used to examine the diadromous migration and small‐scale movements of a tropical goby (Sicyopterus lagocephalus) within a watershed in La Réunion Island, Indian Ocean. The elemental ratios Sr:Ca, Ba:Ca and Sr:Ba recorded monthly in the water of nine sampling sites varied between localities and were correlated with otolith signatures, whereas the Mg:Ca signature was not. The incorporation of some trace elements in otoliths was influenced by the size of fish and site where they were caught, reflecting an effect of endogenous and exogenous factors. Despite these sources of variation, the elemental signatures did not overlap for three river sections distributed along the 26‐km‐long watershed. The diadromous migration and fish lifetime movements between these river sections were reconstructed using an original process based on random forest analysis. This approach revealed distinct migratory behaviours after fish entered in the river, with some individuals progressing slowly in the watershed whereas other rapidly reached the upper localities. As adults, S. lagocephalus showed a restricted exploratory behaviour and a strong site fidelity to a particular part of the watershed. The detection of adult movement was typically only between adjacent locations and is possibly explained by shifts in local intraspecific hierarchies and/or displacement during extreme discharge caused by cyclones.     

Histopathological findings,phenotyping of inflammatory cells,and expression of markers of nitritative injury in joint tissue samples from calves after vaccination and intraarticular challenge with Mycoplasma bovis strain 1067

Background

The pathogenesis of caseonecrotic lesions developing in lungs and joints of calves infected with Mycoplasma bovis is not clear and attempts to prevent M. bovis-induced disease by vaccines have been largely unsuccessful. In this investigation, joint samples from 4 calves, i.e. 2 vaccinated and 2 non-vaccinated, of a vaccination experiment with intraarticular challenge were examined. The aim was to characterize the histopathological findings, the phenotypes of inflammatory cells, the expression of class II major histocompatibility complex (MHC class II) molecules, and the expression of markers for nitritative stress, i.e. inducible nitric oxide synthase (iNOS) and nitrotyrosine (NT), in synovial membrane samples from these calves. Furthermore, the samples were examined for M. bovis antigens including variable surface protein (Vsp) antigens and M. bovis organisms by cultivation techniques.

Results

The inoculated joints of all 4 calves had caseonecrotic and inflammatory lesions. Necrotic foci were demarcated by phagocytic cells, i.e. macrophages and neutrophilic granulocytes, and by T and B lymphocytes. The presence of M. bovis antigens in necrotic tissue lesions was associated with expression of iNOS and NT by macrophages. Only single macrophages demarcating the necrotic foci were positive for MHC class II. Microbiological results revealed that M. bovis had spread to approximately 27% of the non-inoculated joints. Differences in extent or severity between the lesions in samples from vaccinated and non-vaccinated animals were not seen.

Conclusions

The results suggest that nitritative injury, as in pneumonic lung tissue of M. bovis-infected calves, is involved in the development of caseonecrotic joint lesions. Only single macrophages were positive for MHC class II indicating down-regulation of antigen-presenting mechanisms possibly caused by local production of iNOS and NO by infiltrating macrophages.     

Modeling the dynamics of backyard chicken flows in traditional trade networks in Thailand: implications for surveillance and control of avian influenza

In Southeast Asia, traditional poultry marketing chains have been threatened by epidemics caused by the highly pathogenic avian influenza H5N1 (HPAI H5N1) virus. In Thailand, the trade of live backyard chickens is based on the activities of traders buying chickens from villages and supplying urban markets with chicken meat. This study aims to quantify the flows of chickens traded during a 1-year period in a province of Thailand. A compartmental stochastic dynamic model was constructed to illustrate trade flows of live chickens from villages to slaughterhouses. Live poultry movements present important temporal variations with increased activities during the 15 days preceding the Chinese New Year and, to a lesser extent, other festivals (Qingming Festival, Thai New Year, Hungry Ghost Festival, and International New Year). The average distance of poultry movements ranges from 4 to 25 km, defining a spatial scale for the risk of avian influenza that spread through traditional poultry marketing chains. Some characteristics of traditional poultry networks in Thailand, such as overlapping chicken supply zones, may facilitate disease diffusion over longer distances through combined expansion and relocation processes. This information may be of use in tailoring avian influenza and other emerging infectious poultry disease surveillance and control programs provided that the cost-effectiveness of such scenarios is also evaluated in further studies.