Objective: To establish a novel and highly specific loop-mediated isothermal amplification (LAMP) assay for the identification of nervous necrosis virus (NNV) infection. Methods: A set of synthesized primers was used to match the sequences of a specific region of the nnv gene from the National Center for Biotechnology Information database, not originating from NNV-infected fish, the efficiency and specificity of LAMP were measured dependent on the concentration of DNA polymerase and the reaction temperature and time. In addition, to determine species-specific LAMP primers, cross reactivity testing was applied to the reaction between NVV and other virus families including viral hemorrhagic septicemia virus and marine birnavirus. Results: The optimized LAMP reaction carried out at 64 °C for 60 min, and above 4 U Bst DNA polymerase. The sensitivity of LAMP for the detection of nnv was thus about 10 times greater than the sensitivity of polymerase chain reaction. The LAMP assay primers were specific for the detection NNV infection in Epinephelus septemfasciatus. Conclusions: The development of LAMP primers based on genetic information from a public database, not virus-infected samples, may provide a very simple and convenient method to identify viral infection in aquatic organisms.

Objective: To screen the fatty acid (FA) composition of 20 marine microalgae species, including seven Diophyceae, six Bacillariophyceae, four Chlorophyceae, two Haptophyceae and one Raphidophyceae species. Methods: Microalgal cells cultured at the Korea Institute of Ocean Science & Technology were harvested during the late exponential growth phase and the FA composition analyzed. Results: The FA composition of microalgae was species-specific. For example, seven different species of Dinophyceae were composed primarily of C14:0, C16:0, C18:0, C20:4n-6, C20:5n-3 and C22:6n-3, while C14:0, C16:0, C16:1, C18:0, C20:5n-3 and C22:6n-3 were abundant FAs in six species of Bacillariophyceae. In addition, four Chlorophyceae, two Haptophyceae and one Raphidophyceae species all contained a high degree of C16:1n-7 [(9.28-34.91)% and (34.48-35.04)%], C14:0 [(13.34-25.96)%] and [(26.69-28.24)%], and C16:0 [(5.89-29.15)%] and [(5.70-16.81)%]. Several factors contribute to the nutritional value of microalgae, including the polyunsaturated FA content and n-3 to n-6 FA ratio, which could be used to assess the nutritional quality of microalgae. Conclusions: This study is the first comprehensive assessment of the FA composition and nutritional value of microalgae species in South Korea, and identifies the potential utility of FAs as species-specific biomarkers.