Chun Mae Dong

Population genetic structure of Korean pen shell ( Atrina pectinata ) in Korea inferred from microsatellite marker analysis

The Korean pen shell Atrina pectinata is a commercially valuable species in Korea. The commercial catch of this fish has decreased continuously since 1990. However, its genetic characteristics have never been studied. In order to explore the population genetic structure of this species, 125 pen shells sampled from three major habitats along the western coast of Korea were genotyped at 21 microsatellite loci. Relatively high levels of genetic variability (mean number of allelic richness (AR) = 14.74; mean hetrerozygosity (He) = 0.849) was found among localities. However, despite the potential of the Korean pen shell to exhibit genetic structure (adults are sedentary), none of the genetic tests applied in this study detected significant genetic differentiation among the samples. The lack of genetic differentiation among samples may be due to high levels of larval dispersal, through passive drift with ocean currents. Alternatively, populations may have diverged too recently for significant genetic differentiation to have become evident. Furthermore, small sample sizes and the limited number of samples may have hampered the detection of genetic structure. The results of this study therefore suggested a lack of genetic structure among the populations of pen shell of Korean waters and should be managed as a single unit. This information on the genetic characteristics of Korean pen shell populations has important implications for the sustainable exploitation of the fishing resources and the preservation of biodiversity.

Comparison between Wild and Hatchery Populations of Korean Pen Shell (Atrina pectinata) Using Microsatellite DNA Markers

Pen shell (Atrina pectinata) is a popular food source with a high commercial value in a number of Asian Pacific areas. The natural A. pectinata population has been declining continuously over the past several decades. Microsatellite DNA markers are a useful DNA-based tool for monitoring the genetic variation of pen shell populations. In this study, 20 polymorphic microsatellite (MS) DNA markers were identified from a partial genomic pen shell DNA library enriched in CA repeats, and used to compare allelic variation between wild and hatchery pen shell populations in Korea. A total of 438 alleles were detected at the 20 MS loci in the two populations. All loci were easily amplified and demonstrated allelic variability, with the number of alleles ranging from 5 to 35 in the wild population and from 5 to 22 in the farmed population. The average observed and expected heterozygosities were 0.69 and 0.82, respectively, in the hatchery samples and 0.69 and 0.83, respectively, in the wild samples. Statistical analysis of fixation index (FST) and analysis of molecular variance (AMOVA) showed minor, but significant, genetic differences between the wild and hatchery populations (FST = 0.0106, CI95% = 0.003–0.017). These microsatellite loci may be valuable for future aquaculture and population genetic studies for developing conservation and management plans. Further studies with additional pen shell samples are needed to conclusively determine the genetic diversity between the wild and hatchery populations.

New polymorphic microsatellite markers in Pacific abalone Haliotis discus hannai and their application to genetic characterization of wild and aquaculture populations

Seven new microsatellite markers were developed for the Pacific abalone (Haliotis discus hannai, Haliotidae), and allelic variability was compared between a wild population and a hatchery population in Yeosu, Korea. All loci amplified readily and demonstrated allelic variability, with the number of alleles ranging from 6 to 15 in the wild population and from 3 to 12 in farmed populations. Average observed and expected heterozygosities were estimated at 0.65 and 0.77 in the hatchery samples, and 0.79 and 0.87 in the wild samples. These results indicated lower genetic variability in the hatchery population, as compared with the wild population and significant genetic differentiation between the wild population and the hatchery samples (FST=0.055, p<0.001). These microsatellite loci may be valuable for future population genetic studies and for tracking hatchery samples used in stock enhancement programs.

Novel Polymorphic Microsatellite Loci for the Korean Black Scraper (Thamnaconus modestus), and Their Application to the Genetic Characterization of Wild and Farmed Populations

In this study, we developed 20 polymorphic microsatellite markers for the Korean black scraper, Thamnaconus modestus (Günther, 1877), Monacanthidae, and used them to compare allelic variation between wild and hatchery populations in Korea. All loci were readily amplified and demonstrated allelic variability, with the number of alleles ranging from 5–35 in the wild population and 5–22 in the farmed population. The average observed and expected heterozygosities were estimated, respectively, as 0.74 and 0.80 in the hatchery samples and 0.78 and 0.81 in the wild ones. These results indicate lower genetic variability in the hatchery population than in the wild population and minor, but significant, genetic differentiation between the two populations (FST = 0.005, P < 0.01). Additionally, cross-amplification was tested in another monacanthid species, Stephanolepis cirrhifer; many loci were found that yielded useful information. The high degree of polymorphism exhibited by the 20 microsatellites will be useful in future aquaculture and population genetic studies for developing conservation and management plans.

Four Members of Heat Shock Protein 70 Family in Korean Rose Bitterling (Rhodeus uyekii)

Heat shock protein (HSP) 70, the highly conserved stress protein families, plays important roles in protecting cells against heat and other stresses in most animal species. In the present study, we identified and characterized four Hsp70 (RuHSP4, RuHSC70, RuHSP12A, RuGRP78) family proteins based on the expressed sequence tag (EST) analysis of the Korean rose bitterling R. uyekii cDNA library. The deduced RuHSP70 family has high amino acid identities of 72-99% with those of other species. Phylogenetic analysis revealed that RuHsp70 family clustered with fish groups (HSP4, HSC70, HSP12A, GRP78) proteins. Quantitative RT-PCR analysis showed the specific expression patterns of RuHsp70 family members in the early developmental stages and several tissues in Korean rose bitterling. The expression of 4 groups of Hsp70 family was detected in all tested tissue. Particularly, Hsp70 family of Korean rose bitterling is highly expressed in hepatopancreas and sexual gonad (testis and ovary). The expression of Hsp70 family was differentially regulated in accordance with early development stage of Rhodeus uyekii.

Development and characterization of microsatellite markers for genetic analysis of the Korean black scraper, Thamnaconus modestus

Black scraper is a commercially important oceanodromous fish in Korea. The commercial catch of this fish has decreased continuously since 1990. However, its genetic characteristics have never been studied. For population genetic analysis to assist effective aquaculture and stock management efforts, we isolated and characterized 19 microsatellite loci using an microsatellite-enrichment method based on magnetic/biotin capture of microsatellite sequences from a size-selected genomic library. To characterize each locus, 30 individuals from a natural T. modestus population in southern Korea were genotyped. All loci except two, KTm213 and KTm284, were polymorphic, with an average of 15.18 alleles per locus (range, 2–41). The mean observed and expected heterozygosities were 0.67 (range, 0.33–0.97) and 0.79 (range, 0.40–1.00), respectively. A significant deviation from Hardy-Weinberg equilibrium was observed at six loci (KTm142, KTm145, KTm158, KTm24, KTm221, and KTm250). This high variability indicates that these microsatellites may be useful for high-resolution studies of population genetics.