ISSN : 1225-3480
Three marine mollusk species were collected in 2019 years from the Jeju island waters of Korea. They wereidentified as Monoplex exaratus (Reeve, 1844), Mipus eugeniae (Bernardi, 1853), and Electroma alacorvi (Dillwyn,1817) that come out into the unrecorded species in Korea. As a result, Korean Cymatiidae was 11 species ofseven genera, the Muricidae was 22 species of 13 genera, and the Family Vulsellidae, to which E. alacorvibelongs, is first recorded in Korea.
The neritid Clithon retropictum (v. Martens, 1870) is listed as a second-grade endangered mollusk species inKorea, inhabiting river mouths and estuaries on the south coast and Jeju Island. C. retropictum has been identifiedfrom four localities on Jeju Island, two on the north and the other two on the south coasts. Recent surveys on thenorthern coast of Jeju Island indicated that a small population of C. retropictum inhabits the river mouth ofGosung-Cheon stream located near Hagwi fishing port on the northern Jeju Island. In the newly found locality, weidentify several adult sizes of C. retropictum and the numerous egg capsules attached to rocks. Accordingly, wereport the new habitat of the estuarine gastropod on the northern coast of Jeju Island.
This study was conducted to measured the survival rate of Crassostrea gigas according to the salinity when thewater temperature is high. In laboratory, the mortality test was performed on the C. gigas, we conductedexperiments at water temperature 20, 25, and 30℃, salinity was tested at intervals 5 psu from 0 to 35 psu. At 20℃, mortality was only seen at low salinity below 5 psu, on the other hand, above 25℃, the mortality was 100% at5 psu, and it was all survived at the above 30 psu. However, at a water temperature of 30℃ or higher, allindividuals died regardless of the concentrations of salinity. However, as a result of measuring the clearance rate,it was found that the feeding activity was performed only at 30 psu and 35 psu at 20℃ and 25℃, respectively. Andat 30℃, it was found that feeding activity was not performed at all concentrations of salinity. It was confirmed thatexposure to low-salt water during high water temperature affects the feeding and survival of C. gigas.
This study was performed to oxygen consumption and hemolymph composition of Pacific oyster of according to water temperature. Oxygen consumption of Pacific oyster was increased with rising water temperature. Ammonia excretion was significantly increased with rising water temperature. The oxygen consumption R2 value was 0.9765, indicating a high correlation (Q10). Na+ K+ and Cl- concentrations of hemolymph were significantly increased with 25℃ water temperature. There was no significant difference in the values of glucose. Levels of hemolymph alanine aminotransferase (ALT) were significantly increased with 25℃ water temperature.
The climate change causes the mass mortality of farmed fish and shellfish. Therefore, it is important to comprehend clearly the physical and molecular mechanisms of abalone under heat stress condition. In order to find genes involved in biological response to heat stress, we have performed sequencing of transcriptome in two different group of the pacific abalone (Haliotis discus hannai), the breeding line group and the general aquaculture group, after adaptive treatment (18°C → 20°C → 25°C → 30°C) or acute treatment (18°C → 30°C for 0.5hr, 1hr, 3hr or 6hr). Tissue-specific differential expression genes (DEGs) were identified with 52 genes in gonad, 28 in hemocytes, 36 in gills, 31 in muscle and 33 in mantle under different heat shock conditions. There was no significantly differentially expressed pattern of transcriptome in the tested tissues between two groups, except the DEGs from the gonad tissues. Among them, the expression patterns of the XBP1, OS9, VCP, SNRNP70, MGAT2, UBA5, DST, ST13, YOD1 and ERP44 genes in the gonad tissue of the breeding line group showed significant differences from those of all tissues in the general aquaculture group. The present study provides a foundation for understanding the molecular mechanism of heat stress tolerance in abalone. Further functional studies should be performed on the heat stress-related genes identified in this study, which can contribute to the molecular breeding for heat stress tolerance in abalone.
Clithon retropictus is a small gastropod belonging to Neritidae that lives in gravel areas of the brackish water zone. Due to these limited habitat conditions and indiscriminate coastal development, it has been designated as a second-class endangered species since 2005. Although its continued interest is low, it is important to investigate the endangered species-specific characterization and analysis of its genetic information. As of June 2021, genetic information of C. retropictus registered in the NCBI was 78 cases, and related studies are also insufficient. In addition, it has not yet been studied the identification and functional characterization of MT gene, which plays a critical role in controlling metal toxicity and oxidative stress, in C. retropictus. In this context, we analyzed basic structure and specific domains of MT sequence of C. retropictus (CrMT) and the taxonomic location of CrMT with its othologs registered in NCBI. As a result, CrMT gene containing with mollusca-specific MT pattern was identified in C. retropictus. In addition, phylogenetic analysis through the maximum-likelihood method indicates that C. retropictus was closely related to the order Lepetelida inhabiting the sea. Taken together, our results may support basic information of endangered species living in brackish water zone.
