Kudoa ogawai (Myxosporea: Kudoidae) Infection in Cultured Olive Flounder Paralichthys olivaceus

Since Kudoa septempuntata was identified as a causative agent of food poisoning associated with raw olive flounder Paralichthys olivaceus, interest and concern regarding the parasite have increased. However, there have been no investigations or reports of other Kudoa species infecting the fish (except for K. paralichthys, which infects the brain) in Korea. We found cysts filled with myxospores of Kudoa species in muscles of cultured olive flounder specimens and identified these to the species level. Mature spores were quadrate, measuring 8.7±0.5 μm in length, 9.2±0.4 μm in thickness, and 12.9±0.6 μm in width. The spores containing 4 polar capsules had a length of 2.1±0.2 μm and a width of 1.8±0.3 μm. The partial 18S and 28S rDNA of isolates showed 99–100% similarities with K. ogawai. Using these morphological and molecular analyses, the species was identified as K. ogawai. This study is the first report of K. ogawai infection in cultured olive flounder in Korea.

Sinuolinea capsularis (Myxosporea: Sinuolineidae) Isolated from Urinary Bladder of Cultured Olive Flounder Paralichthys olivaceus

Sinuolinea capsularis Davis, 1917 is myxosporean that infect the urinary system of the host fish. Insufficient morphological and molecular data of S. capsularis exits, and it is therefore difficult to make an accurate identification of the parasite. We tried a series of morphological and molecular analysis to identify an myxosporean isolated from urinary bladder of cultured olive flounder, Paralichthys olivaceus, from Jeju island in the Republic of Korea. Some of them were observed under a light microscope and SEM, and remain samples were used molecular and phylogenetic analysis. Mature spores were subspherical, measuring 13.9±0.6 μm in length and 13.8±0.8 μm in width. Two spherical polar capsules on opposite sides in the middle of the spore had a diameter range of 4.3±0.4 μm. Scanning electron microscopy revealed that spores a severely twisted the suture line. By the morphological comparison and analysis, it was identified as S. capsularis. In addition, we obtained the partial 18S rDNA of S. capsularis and first registered it in NCBI. Phylogenetic analysis showed that S. capsularis clustered with Zschokkella subclade infecting the urinary system of marine fish, and it supported the infection site tropism effect on phylogeny of marine myxosporeans as well as the origin of Sinuolinea is not monophyly.

Development of a multiplex PCR assay to detect Edwardsiella tarda, Streptococcus parauberis, and Streptococcus iniae in olive flounder (Paralichthys olivaceus)

A multiplex PCR protocol was established to simultaneously detect major bacterial pathogens in olive flounder (Paralichthys olivaceus) including Edwardsiella (E.) tarda, Streptococcus (S.) parauberis, and S. iniae. The PCR assay was able to detect 0.01 ng of E. tarda, 0.1 ng of S. parauberis, and 1 ng of S. iniae genomic DNA. Furthermore, this technique was found to have high specificity when tested with related bacterial species. This method represents a cheaper, faster, and reliable alternative for identifying major bacterial pathogens in olive flounder, the most important farmed fish in Korea.

External Application of Fermented Olive Flounder (Paralichthys olivaceus) Oil Alleviates Inflammatory Responses in 2,4-Dinitrochlorobenzene-induced Atopic Dermatitis Mouse Model

Allergic skin inflammation such as atopic dermatitis (AD) is characterized by edema and infiltration with various inflammatory cells such as mast cells, basophils, eosinophils and T cells. Thymic stromal lymphopoietin (TSLP) is produced mainly by epidermal keratinocytes, as well as dermal fibroblasts and mast cells in the skin lesions of AD. Omega-3 polyunsaturated fatty acids in fish oil can reduce inflammation in allergic patients. Fermentation has a tremendous capacity to transform chemical structures. The anti-inflammatory effects of fish oil have been described in many diseases, but the beneficial effects by which fermented olive flounder oil (FOF) modulates the allergic response is poorly understood. In this study, we produced FOF and tested its ability to suppress the various allergic inflammatory responses. The ability of FOF to modulate the immune system was investigated using a mouse model of AD. The FOF-treated group showed significantly decreased immunoglobulin E (IgE) and histamine in serum. Also, the increased TSLP expression was significantly inhibited in the FOF group; the FOF-treated group was not appreciably different from the hydrocort cream treatment group. In addition, FOF treatment resulted in a smaller spleen size with reduced the thickness and length compared to the induction group. Splenocytes from mice treated with FOF produced significantly less IFN-gamma, IL-4, T-box transcription factor (T-bet) and GATA binding protein 3 (GATA3) expression compared with the induction group. These results suggest that FOF may be effective in treating the allergic symptoms of AD. 5.