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Abstract Background EST sequencing is one of the most efficient means for gene discovery and molecular marker development, and can be additionally utilized in both comparative genome analysis and evaluation of gene duplications. While much progress has been made in catfish genomics, large-scale EST resources have been lacking. The objectives of this project were to construct primary cDNA libraries, to conduct initial EST sequencing to generate catfish EST resources, and to obtain baseline information about highly expressed genes in various catfish organs to provide a guide for the production of normalized and subtracted cDNA libraries for large-scale transcriptome analysis in catfish. Results A total of 17 cDNA libraries were constructed including 12 from channel catfish (Ictalurus punctatus) and 5 from blue catfish (I. furcatus). A total of 31,215 ESTs, with average length of 778 bp, were generated including 20,451 from the channel catfish and 10,764 from blue catfish. Cluster analysis indicated that 73% of channel catfish and 67% of blue catfish ESTs were unique within the project. Over 53% and 50% of the channel catfish and blue catfish ESTs, respectively, had significant similarities to known genes. All ESTs have been deposited in GenBank. Evaluation of the catfish EST resources demonstrated their potential for molecular marker development, comparative genome analysis, and evaluation of ancient and recent gene duplications. Subtraction of abundantly expressed genes in a variety of catfish tissues, identified here, will allow the production of low-redundancy libraries for in-depth sequencing. Conclusion The sequencing of 31,215 ESTs from channel catfish and blue catfish has significantly increased the EST resources in catfish. The EST resources should provide the potential for microarray development, polymorphic marker identification, mapping, and comparative genome analysis.

White spot disease in penaeid shrimp is caused by the white spot syndrome virus (WSSV). It is the most economically important disease of farmed warm‐water shrimp, causing extensive economic losses estimated from $8 to $15 billion since its emergence in the 1990s. Early diagnosis of disease is critical in the management of outbreaks and to avoid crop losses. Diagnosis of white spot disease is generally carried out in centralized laboratory settings using molecular biology approaches. However, this mode of testing can be expensive and time consuming, requiring laboratory equipment, highly trained laboratory personnel, dedicated laboratory space, and long‐distance transportation of samples from field to lab. In‐field diagnostics are gaining credence as tools for rapid and early animal disease detection, allowing diagnosticians and farmers to potentially manage disease outbreaks from the pond side. In the present study, we describe the development and application of a new in‐field point‐of‐need diagnostic test and platform for the diagnosis of WSSV in remote settings (shrimp farms). We report its performance in laboratory and field settings and compare it with current gold‐standard diagnostic approaches. We discuss the potential benefits (and barriers to uptake) of applying such testing in the global shrimp farming sector. [ABSTRACT FROM AUTHOR]

Ornamental fishes were collected from 173 locations in nine provinces of Thailand during 2016-2018. Using real-time PCR analysis, twelve fish species of three families (Poeciliidae, Cichlidae and Osphronemidae) were found positive for Megalocytivirus, a pathogenic agent which causes a significantly high mortality in a wide range of aquatic animal hosts. A geographic information system (GIS) displayed the distribution of megalocytivirus to the northern, central and western regions of Thailand. Nevertheless, one sampling province showed megalocytivirus-free status and the overall rate of virus occurrence declined by 10% during the study period. The transport and translocation of ornamental fish could be a key route for megalocytivirus introduction to new geographical areas. Molecular phylogenetic analysis based on the major capsid protein (MCP) confirmed that Megalocytivius in the current study belongs to members of an infectious spleen and kidney necrosis virus (ISKNV) cluster. Although most infected fish were asymptomatic, non-specific symptoms such as haemorrhages, loss of coloration on the fish body and pale liver were observed without substantial mortality. Cytomegalic cells with inclusion bodies were examined. Issues associated with host molecular defense mechanism, persistent infection, and mortality risk factors will await further study. [ABSTRACT FROM AUTHOR]