Comparative Susceptibility of Channel Catfish,Ictalurus punctatus; Blue Catfish,Ictalurus furcatus; and Channel (♀) × Blue (♂) Hybrid Catfish to Edwardsiella piscicida,Edwardsiella tarda,and Edwardsiella anguillarum

Members of the genus Edwardsiella are important pathogens of cultured and wild fish globally. Recent investigations into the phenotypic and genotypic variation of Edwardsiella tarda have led to the segregation of E. tarda into three distinct taxa: E. tarda, Edwardsiella piscicida, and Edwardsiella anguillarum. In catfish aquaculture in the southeastern USA, E. piscicida has been more commonly associated with disease than E. tarda or E. anguillarum, and recent research has demonstrated E. piscicida to be more pathogenic in channel catfish than E. tarda or E. anguillarum. Anecdotal reports from industry suggest an increased prevalence of E. piscicida associated with the culture of channel (♀) × blue (♂) hybrid catfish. This work investigated the comparative susceptibility of channel catfish, blue catfish, and their hybrid cross to molecularly confirmed isolates of E. tarda, E. piscicida, and E. anguillarum. There was significantly higher mortality in hybrid catfish compared to channel catfish following intracoelomic injection of E. piscicida. To our knowledge, E. piscicida is the first bacterial pathogen to demonstrate increased pathogenicity in hybrid catfish compared to channel catfish.     

A review of alpha2 adrenoreceptor agonists and the development of hypoxemia in domestic and wild ruminants.

Alpha2 agonists are commonly used in combination with other anesthetic agents to chemically immobilize wildlife and may cause potentially serious hypoxemia in wild ruminants. In some domestic ruminants, they are associated with significant changes to the pulmonary parenchyma, increased venous admixture, pulmonary edema, and hypoxemia. Effective and safe immobilization of these animals requires knowledge of the mechanisms behind these changes and the methods that offset their effects, including the use of supplemental oxygen.     

Oncolytic reovirus synergizes with chemotherapeutic agents to promote cell death in canine mammary gland tumor

The oncolytic effects of reovirus in various cancers have been proven in many clinical trials in human medicine. Oncolytic virotherapy using reovirus for canine cancers is being developed in our laboratory. The objective of this study was to examine the synergistic anti-cancer effects of a combination of reovirus and low doses of various chemotherapeutic agents on mammary gland tumors (MGTs) in dogs. The first part of this study demonstrated the efficacy of reovirus in canine MGTs in vitro and in vivo. Reovirus alone exerted significant cell death by means of caspase-dependent apoptosis in canine MGT cell lines. A single injection of reovirus impeded growth of canine MGT tumors in xenografted mice, but was insufficient to induce complete tumor regression. The second part of this study highlighted the anti-tumor effects of reovirus in combination with low doses of paclitaxel, carboplatin, gemcitabine, or toceranib. Enhanced synergistic activity was observed in the MGT cell line treated concomitantly with reovirus and in all the chemotherapeutic agents except toceranib. In addition, combining reovirus with paclitaxel or gemcitabine at half dosage of half maximal inhibitory concentration (IC₅₀) enhanced cytotoxicity by activating caspase 3. Our data suggest that the combination of reovirus and low dose chemotherapeutic agents provides an attractive option in canine cancer therapy.     

Distribution of toxigenic Escherichia coli serotypes in the intestines of infants.

As part of an ongoing study into the pathogenesis of sudden infant death syndrome (SIDS), the distribution of serotypes of toxigenic and non-toxigenic Escherichia coli within the gastrointestinal tract of babies who had died was investigated. Escherichia coli isolates from the mid-ileum, colon and rectum of six SIDS cases and one case which had died suddenly and unexpectedly but had underlying cardiac pathology were "O" serogrouped and examined for verocytoxic activity and production of heat-labile enterotoxin. In addition, the effect of storage of gut specimens and rectal swabs at 4 degrees C on isolation of toxigenic strains was studied in three of the cases. A diversity of serogroups and toxigenicity was a general finding, however, strains found in the proximal gut were also cultured from the rectum, indicating that faecal specimens would be a valid tool in investigating the role of these organisms in SIDS cases compared with healthy controls. Storage for up to 5 days at 4 degrees C had no appreciable effect on isolation rates of toxigenic bacteria.     

Digital mapping of soil ecosystem services in Scotland using neural networks and relationship modelling. Part 2: Mapping of soil ecosystem services

A framework for estimating the distribution of soil ecosystem service (ES) supply is described that is based on the concept of matrix multiplication. This approach enables relationships between fundamental soil variables and associated environmental characteristics to be linked to soil processes, and hence to ecosystem functions and ecosystem services. The parameterization of these relationships was achieved using a combination of data from the Scottish Soils Database and expert knowledge. Baseline data to allow mapping of processes, functions and services across Scotland is given by digital maps of soil classes. The matrix multiplication approach constrains the relationship linkages to linear relationships and ignores potential synergies between factors at each stage, but does provide a mechanism for relating fundamental soil characteristics to ecosystem services. The approach has been tested by developing maps of selected ecosystem services in Scotland and comparing these with existing maps of the same or similar ESs. While the values and their ranges differ in each case, the spatial distribution of services is similar. The proposed mechanism is extensible at every level and can also be used to explore the impacts of land management options on environmental characteristics. This is demonstrated by using the model to estimate impacts of liming on three ecosystem services: Agricultural Capability, Carbon Sequestration and Drinking Water Provision. The model is shown to produce reasonable estimation of the impacts of this management option. Further discussion of improvements to the system and its potential applications is given.     

Application of multiplex quantitative polymerase chain reaction methods to detect common bacterial fish pathogens in Nile tilapia,Oreochromis niloticus,hatcheries in Costa Rica

Edwardsiella spp., Streptococcus spp., and Francisella noatunensis subsp. orientalis are some of the most important fish pathogens affecting global tilapia, Oreochromis spp., aquaculture. In Costa Rica, the aquaculture industry is dominated by freshwater‐cultured Nile tilapia, Oreochromis niloticus, which are raised in all seven national provinces. At present, little is known regarding the diversity of pathogens present in these facilities, and definitive identification of agents associated with disease outbreaks are rare. To evaluate the prevalence of common bacterial pathogens in these systems, this study used multiplex quantitative polymerase chain reaction (qPCR) assays targeting Edwardsiella, Streptococcus, and Francisella species as a diagnostic and surveillance tool. In 2017, seven different tilapia hatcheries were visited, and 350 fingerlings were subjected to necropsy and molecular diagnostic evaluation. Fish exhibiting gross signs of disease were subjected to histological and microbiological analysis. For the first time, Edwardsiella anguillarum was recovered and molecularly confirmed from diseased tilapia in Costa Rica. In addition, F. noatunensis subsp. orientalis was identified in a region of Costa Rica where it had not been previously reported.     

Effects of Mosquitofish,Gambusia affinis,on Channel Catfish,Ictalurus puncatatus,Production Ponds

Mosquitofish, Gambusia sp., have been spread throughout the world to biologically control mosquitoes. However, the fish has gained a reputation as an invasive species and has been implicated in displacing native aquatic species. Gambusia affinis are native to the southeastern United States and commonly occur in commercial channel catfish, Ictalurus punctatus, production ponds. We investigated effects of mosquitofish presence on zooplankton populations, water quality, disease occurrence, and fish production in experimental ponds. There were no differences between ponds with or without mosquitofish in numbers of calanoid copepods, cyclopoid copepods, total copepods, Bosmina sp., Ceriodaphnia sp., Moina sp., Daphnia sp., or total cladocerans. There were also no differences in copepod and cladoceran sizes. Copepod nauplii were more numerous during the summer months in ponds with mosquitofish. There were no differences in water quality variables (soluble reactive phosphorus, nitrate, nitrite, ammonia, total nitrogen, total phosphorus, pH) or phytoplankton density between ponds stocked with and without mosquitofish. Catfish production and disease occurrence were also similar between ponds with and without mosquitofish. Although mosquitofish may cause problems when stocked outside their native range, there does not appear to be any adverse effects of mosquitofish presence in catfish production ponds.