Joon Bum Jeong

Influence of temperature shifts on the onset and development of red sea bream iridoviral disease in rock bream Oplegnathus fasciatus.

The effects of various water temperature treatments on the development of red sea bream iridovirus disease (RSIVD) in rock bream Oplegnathus fasciatus challenged with iridovirus Sachun (IVS-1) were determined by measuring the mortality and the viral concentration in the spleen of infected fish. Experimental infections of rock bream with IVS-1 at water temperatures of 18, 21, and 25 degrees C resulted in a cumulative mortality of 100%, but infections at 13 degrees C resulted in 0% mortality, even after 45 d. The disease progressed more rapidly at higher water temperatures; at 25, 21, and 18 degrees C, the mean numbers of days until death were 17, 20, and 30 d, respectively. When the water temperature for fish infected with iridovirus by intramuscular injection was shifted from 13 to 25 degrees C, the cumulative mortality reached 100%, with rapid onset of the disease, independent of the time at which the temperature was shifted, i.e. 7, 14, or 30 d after injection at 13 degrees C. Real-time PCR data revealed that the viral genome copy number in the spleen of rock bream maintained at 13 degrees C increased with time, suggesting the occurrence of viral replication even at 13 degrees C. In the reverse experiment, when the water temperature for fish that were infected at a higher temperature was shifted to 13 degrees C, 3 or 7 d after injection at 25 degrees C, the fish showed 100% cumulative mortality, although the mean number of days until death was higher than that observed for fish maintained at a constant temperature of 25 degrees C. The viral DNA concentration in the spleen of rock bream that had been shifted down to 13 degrees C, 3 or 7 d after injection at 25 degrees C, was not suppressed, but increased and eventually reached levels sufficient to induce mortality at 13 degrees C. However, the level of viral genome copy numbers in the spleen of dead fish at 25 degrees C, regardless of whether those fish were held at a constant temperature of 25 degrees C or shifted up from 13 degrees C, appeared to be greater than the level found in the dead fish shifted down to 13 degrees C after inoculation at 25 degrees C.

Effects of Dietary Supplementation of Fermented Garlic Powder on Immune Responses, Blood Components, and Disease Resistance against Principal Fish Disease of Juvenile Olive Flounder, Paralichthys olivaceus in Low Temperature Season

We report non-specific immune responses and disease resistance against Vibrio anguillarum, Streptococcus iniae and Edwardsiella tarda by dietary supplementation of fermented garlic powder (FGP) in olive flounder for the first time. Four isonitrogenous (45% crude protein) and isocaloric (17.1 MJ/kg) diets were formulated to have 0%, 0.5%, 1% and 2% of the FGP (G-0, G-0.5, G-1 and G-2). The experimental diets were fed to juvenile olive flounder averaging 23.4 g in triplicate groups (90 fish/group) in a flow-through system. After a five-week feeding trial, healthy fish with similar sizes from each tank were selected and injected with 1 ml of three bacteria each to evaluate disease resistance of the fish. During the 5-week feeding trial, the weight gain, specific growth rate, feed conversion ratio, protein efficiency ratio, and survival of the fish were not significantly affected by the experimental diets. However, feed intake was significantly lower (P<0.05) in the fish fed the G-2 diet compared with the control group. Hemoglobin, myeloperoxidase activity, cholesterol and HDL-cholesterol were not different between the dietary groups. However, hematocrit, nitroblue tetrazolium (NBT) activity, and lysozyme activity were increased (P<0.05) with an increment of dietary FGP. Plasma triglyceride of the fish fed the G-0.5 diet was significantly lower than that of fish fed the control diet. The cumulative mortality was lower in the fish fed diets containing FGP compared with the control group in the challenge test except for the bacteria Edwardsiella tarda. The results in this study indicate that dietary supplementation of FGP can enhance the non-specific immune responses and disease resistance of olive flounder against V. anguillarum and S. iniae. (Key words : Olive flounder, Fermented garlic powder, Non-specific immune response, Challenge test)

Water extract of processed Hydrangea macrophylla (Thunb.) Ser. leaf attenuates the expression of pro-inflammatory mediators by suppressing Akt-mediated NF-κB activation.

Although Hydrangea macrophylla is native to Northeast Asia and widely cultivated in many parts of the world, no studies on its anti-inflammatory effects have been reported. In this study, we evaluated the anti-inflammatory effect of a water extract of processed H. macrophylla leaf (WH) in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophage cells. WH inhibited the expression of LPS-stimulated pro-inflammatory mediators such as nitric oxide (NO), prostaglandin E2 (PGE2), and tumor necrosis factor-α (TNF-α), as well as their regulatory genes inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2), and TNF-α without any accompanying cytotoxicity. Moreover, WH significantly suppressed the LPS-induced DNA-binding activity of nuclear factor-κB (NF-κB), as well as the nuclear translocation of the NF-κB subunits, p65 and p50 by suppressing of IκBα phosphorylation and degradation. WH also increased Akt dephosphorylation, leading to the suppression of the DNA-binding activity of NF-κB in LPS-stimulated RAW264.7 macrophage cells. Our results indicate that WH downregulates the expression of pro-inflammatory mediators such as NO, PGE2, and TNF-α by suppressing the Akt-mediated NF-κB activity in LPS-stimulated RAW264.7 macrophage cells.

Molecular characterization and gene expression of Na+-K+-2Cl− cotransporter2 (NKCC2) in the gastrointestinal tract of Olive flounder (Paralichythys olivaceus) during the four days after infection with Streptococcus parauberis

This study reports on the molecular characterization and gene expression of Na+-K+-2Cl− cotransporter2 (NKCC2) in the gastrointestinal tract of Olive flounder Paralichythys olivaceus infected with Streptococcus parauberis. It examines the electroneutral cation-Cl− cotransporter, and NKCC2 expressed in the intestinal tract. First, we isolated cDNA encoding NKCC2 from the intestinal tract of Olive flounder and investigated the tissue distribution pattern of NKCC2 mRNA. Reverse transcription-PCR analysis detected expressions of NKCC2 in the intestine and kidney. A quantitative PCR analysis showed that the expression level of NKCC2 in the anterior and posterior intestines was higher than in the rectum. Second, we performed a challenge experiment comparing physiological saline (PS) and PS plus the bacteria and analyzed the subsequent gene expression of NKCC2. At 4 days after bacterial injection the comparison between treatment and control found that the expression levels of NKCC2 mRNA increased significantly in the posterior intestine of infected fish but not in the other segments. We discuss the suggestion that bacterial injection may disturb the ion uptake that provides the driving force for water absorption through parts of the intestinal wall.

Gillisia marina sp. nov., from seashore sand, and emended description of the genus Gillisia

A Gram-staining-negative, strictly aerobic, rod-shaped bacterium, designated CBA3202(T), was isolated from seashore sand on Jeju Island, Republic of Korea. Based on the 16S rRNA gene sequence analysis, strain CBA3202(T) was allocated to the genus Gillisia (family Flavobacteriaceae) and was most closely related to the type strain of Gillisia mitskevichiae (99.0 % 16S rRNA gene sequence similarity). Optimal growth occurred at 25 °C and with 3 % NaCl. The only isoprenoid quinone was menaquinone-6 (MK-6), the predominant fatty acids were C16 : 0, iso-C15 : 1 G, iso-C16 : 0 and summed feature 3 (comprising C16 : 1ω6c and/or C16 : 1ω7c), and the DNA G+C content was 34.9 mol%. The polar lipids were phosphatidylethanolamine, two unidentified aminolipids and several unidentified polar lipids. Based on phylogenetic inference and phenotypic data, we conclude that strain CBA3202(T) represents a novel species of the genus Gillisia, for which the name Gillisia marina sp. nov. is proposed. The type strain is CBA3202(T) ( = KACC 16693(T) = KCTC 32030(T) = JCM 18402(T)). An emended description of the genus Gillisia is also provided.

Monitoring of VHS and RSIVD in Cultured Paralichthys olivaceus of Jeju in 2015

In this study, disease surveillance was performed to monitor the prevalence of viral haemorrhagic septicaemia virus (VHSV) and red seabream iridovirus (RSIV) in olive flounder, Paralichthys olivaceus in 2015. The fish samples were collected in March (60 farms), May (55 farms) and July (52 farms) from different farms in Jeju. Reverse transcription polymerase chain reaction (RT-PCR) (VHSV) or PCR (RSIV) results showed that VHSV detected in 2 farms, but RSIV has not been detected in any farms. The sequences of the nucleocapsid protein (N) and gly-coprotein (G) gene of the 2 VHSV isolates were successfully sequenced. Phylogenetic analysis was included VHSV isolates reported here together with a representative VHSV isolates available in GenBank. Phylogenetic analysis in-dicated that most of Korea VHSV isolates were closely related to the Japan and China genotype Ⅳa which is clearly distinct from the North American genotype Ⅳb.

Monitoring of Emaciation Disease in Cultured Olive Flounder Paralichthys olivaceus in Jeju (2010-2013), Korea

1990년대부터 각종 해수어의 양식이 활발하게 이루어져 각국 에서 종묘 수입이 성해지자 방역체계가 미비한 상태에서 수입 종묘와 같이 질병도 함께 도입되어 우리나라에 없었던 질병들 이 유행하기 시작하였으며(Chun, 2006), 질병의 발병 양상 또 한, 양식 초창기에는 고수온기에 기생충 및 세균에 의한 단독 감 염이 주를 이루었으나 최근에는 수온과 상관없이 연중 다양한 병원체가 혼합감염의 형태로 질병을 일으키고 있어 수산 생물 의 대량 폐사를 유발시키기도 한다(Kim et al., 2006). 최근 들어 외래 질병의 유입 가능성이 증가하고 양식 어류의 질병 연관성 에 대한 관심이 증가하면서 질병을 전반적으로 모니터링하거나 질병과의 상관관계를 구명하고자 하는 연구가 점차 증가하고 있는 추세이다(Cho et al., 2009; Jung et al., 2012; Song et al., 제주의 양식 넙치(Paralichthys olivaceus)를 대상으로 한 여윔증 모니터링(2010-2013)