Choon Bok Song

Protective effect of marine algae phlorotannins against AAPH-induced oxidative stress in zebrafish embryo

In this study the protective effect of phlorotannins, including phloroglucinol, eckol, dieckol, eckstolonol and triphloroethol A, isolated from brown algae Ecklonia cava was investigated against AAPH-induced oxidative stress toxicity in zebrafish embryos. Zebrafish embryos were exposed to AAPH and compared with other groups that were co-exposed with phlorotannins until 2-days post-fertilisation. All phlorotannins scavenged intracellular ROS and prevented lipid peroxidation and reduced AAPH-induced cell death in zebrafish embryos. Negative changes in morphological phenomena, such as pericardial oedema, yolk sac oedema, and growth retardation in zebrafish embryos exposed to AAPH were not observed in groups exposed to phlorotannins. These results clearly indicate that phlorotannins possess prominent antioxidant activity against AAPH-mediated toxicity and might be potential therapeutic agents for treating or preventing several diseases implicated with oxidative stress. This study provides a useful tool for examining the protective effect of antioxidants against AAPH-induced oxidative stress in an alternative in vivo model.

Protective effect of dieckol isolated from Ecklonia cava against ethanol caused damage in vitro and in zebrafish model

In the present study, the protective effects of phlorotannins isolated from Ecklonia cava against ethanol-induced cell damage and apoptosis were investigated both in vitro and in vivo. Three phlorotannin compounds, namely phloroglucinol, eckol and dieckol, were successively isolated and identified from the extract. Dieckol showed the strongest protective effect against ethanol-induced cell apoptosis in Chang liver cells, with the lowest cytotoxicity. It was observed that dieckol reduced cell apoptosis through activation of Bcl-xL and PARP, and down-regulation of Bax and caspase-3 in Western blot analyses. In the in vivo study, the protective effect of ethanol induced by dieckol was investigated in a zebrafish model. The dieckol treated group scavenged intracellural reactive oxygen species and prevented lipid peroxidation and ethanol induced cell death in the zebrafish embryo. In conclusion, dieckol isolated from E. cava might possess a potential protective effect against ethanol-induced liver diseases.

Two Unrecorded Species of the Snapper (Perciformes: Lutjanidae) Collected from Jeju Island, Korea

Two unrecorded species of the snapper, Lutjanus malabaricus (296.0 mm standard length [SL]) and L. stellatus (350.0 mm SL) belonging to the family Lutjanidae, were first collected from the western coastal waters of Jeju Island, Korea. L. malabaricus is characterized by having a dark marking on the upper half of the caudal peduncle, a band of vomerine teeth that does not protrude posteriorly at the middle, and nine anal soft rays. Compared to its Korean relative, L. malabaricus is distinguishable by having rows of scales that run obliquely in the dorsal-posterior direction above the lateral line (vs. parallel to the lateral line in L. argentimaculatus). L. stellatus can be identified by the absence of wavy blue lines on the head (vs. many blue lines in L. rivulatus) and presence of a white spot above the lateral line (vs. a black blotch on the lateral line in L. rivulatus). We propose new Korean names, “Jin-hong-tung-dom” and “Huin-jeom-tung-dom,” for L. malabaricus and L. stellatus, respectively.

First Record of the Antrorse Spined Gurnard Pterygotrigla multiocellata (Triglidae, Scorpaeniformes) from Korea

This is the first report of Pterygotrigla multiocellata from the family Triglidae, collected in Korea. The specimen (314 mm in standard length) was caught in a gill net in the coastal waters of Jeju Island on 11 February 2010. This species is characterized by the following morphological traits: head large and triangular, bony plates absent along the base of the second dorsal fin, antrorse rostral spine long, and cleithral spine long. We suggest a new Korean name, “Gin-ppul-mit-seong-dae” for P. multiocellata.

First Record of a Gaper Champsodon longipinnis (Perciformes: Champsodontidae) from Korea

This is the first report of Champsodon longipinnis (Champsodontidae) collected from Korea. The specimen (100.9 mm in standard length) was caught by a bottom trawl in the coastal waters off Busan, Korea. This species is characterized by the following morphological traits: body with small denticulate scales except abdomen around pelvic fin base; posterior end of maxilla extending beyond margin of eye; dark pigmentation on most of the first dorsal fin, upper half of the first to the fourth soft ray of the second dorsal fin, and partial upper lobe of caudal fin. We add C. longipinnis to the Korean fish fauna and suggest a new Korean name, “Jeom-ak-eo-chi,” for the species.

No Response to Bidirectional Size-Based Selection in the Rotifer Brachionus rotundiformis

Although rotifers have been considered the best feeding option for several species of fishes in aquaculture, they are sometimes larger than appropriate for the early larval stage of some marine fishes. Thus, we aimed to determine whether size-based selection of the parents could affect the average body size of their progeny in two clonal populations of the rotifer Brachionus rotundiformis. From each of the clones, 20 individuals were bi-directionally selected toward both smaller and larger sizes and each individualbased selection was conducted for 10 consecutive generations. The results showed that although there were sometimes differences in mean body size between parents and their progeny, no directional trend was observed in all selected lines of both clones. We demonstrated that artificial selection in a rotifer stock cannot lead to an expected size range although they appear to exhibit a large degree of body size polymorphism.

Molecular Phylogenetic Status of Korean Hemiculter Species

We investigated the molecular phylogeny and genetic differences among local populations of Korean Hemiculter fishes based on their mitochondrial cytochrome b gene sequences. Our results indicated that Hemiculter leucisculus populations in China were clearly divided into two groups. The first group (Group 1) included the populations of the Yangtze River and its surrounding areas (including the Qiantangjiang, Lingjiang, Jiulongjiang, and Minjiang rivers); the second group (Group 2) contained local populations from southern China (including the Nanliujiang, Zhujiang, Wanquanhe, Qianjiang, and Nandujiang rivers). The Korean Hemiculter eigenmanni differed in its cytochrome b gene sequence by 0.6-1.0% from the Chinese H. leucisculus (Group 1), which inhabited the Yangtze River and its surrounding areas, suggesting they were phylogenetically close and likely to be the same species. The Korean H. leucisculus differed from the Chinese H. leucisculus (both Groups 1 and 2) by 8.1-9.5%, indicating a very distant phylogenetic relationship; however, the Korean H. leucisculus differed from Hemiculter bleekeri by only 0.5-0.7%, showing intraspecific nucleotide differences. We conclude that the taxonomic relationship between the Korean H. leucisculus and H. bleekeri requires further investigation using type specimens.

Morphological Characteristics of Laemonema nana (Moridae) Collected from the Southern Coastal Waters of Korea

Six adult fish of Laemonema nana, belonging to the family Moridae, were collected in a bottom trawl in the southern coastal waters of Korea. These specimens were characterized by having 46-52 second dorsal fin rays (vs. 57-67 for Lotella phycis and 68 for Physiculus japonicus), two pelvic fin rays (vs. 9 for L. phycis and 6-7 for P. japonicus), and lateral line descending abruptly below the anterior part of the second dorsal fin.