• Fisheries and Aquatic Sciences
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• v.11 no.1
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• pp.32-35
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• 2008

The Suminoe oyster, Crassostrea ariakensis, occurs in estuaries where rivers meet seawater. In Korea, it is one of the most popular fisheries resources in the Nam River and Sumjin River. However, the genetic identification of this species has been questioned, because specimens are often mis-identified as other species. To identify the species, we conducted polymerase chain reaction (PCR) amplification of the internal transcribed spacer-1 (ITS-1) region, followed by digestion with the restriction enzyme HaeIII. Restriction profiles for oysters collected from Korea, Japan, and China (north and south) were determined by comparing the PCR-restriction fragment length polymorphism (RFLP) patterns of the ITS-1 regions. Our study verified that the oysters collected from Korea were C. ariakensis based on the PCR-RFLP patterns. These results emphasize the value of molecular markers for identifying morphologically uncertain species.

• Korean Journal of Environmental Biology
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• v.24 no.1 s.61
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• pp.60-66
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• 2006

This study was carried out to obtain the biological fundamental data for the resources annexation of Crassostrea ariakensis in terms of the effect of temperature and salinity on growth. Water temperature during the sampling period was $3.5\sim26.2^{\circ}C$ and there was a little difference between each sites. Salinity was ranged from 2.6 to 29.5 psu, its maximum in Baealdo and its minimum in Dontak. The fatness index was the higher in Dontak than the other sites. In August, the value was the lowest in 3 sites. Therefore Crassostrea ariakensis is likely to have spawning period June and July. Size values $(mean{\pm}S.D.)$ of shell height was $149.7{\pm}19.8\;mm$ (Baealdo), $148.6{\pm}21.3\;mm$ (Seomjin bridge) and $143.1{\pm}17.6\;mm$ (Dontak), respectively. Relative growth equations among SH, SL, SW, TW and MW of Crassostrea ariakensis were ranged from 0.024 to 0.0471.

• Development and Reproduction
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• v.18 no.3
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• pp.179-186
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• 2014

Characteristics of the developmental stages of spermatids during spermiogenesis and phylogenetic classicfication of the species using sperm ultrastructures in male Crassostrea ariakensis were investigated by transmission electron microscope observations. The morphology of the spermatozoon of this species has a primitive type and is similar to those of Ostreidae. Ultrastructures of mature sperms are composed of broad, modified cap-shaped acrosomal vesicle and an axial rod in subacrosomal materials on an oval nucleus, four spherical mitochondria in the sperm midpiece, and satellite fibres which appear near the distal centriole. The axoneme of the sperm tail shows a 9+2 structure. Accordingly, the ultrastructural characteristics of mature sperm of C. ariakensis resemble to those of other investigated ostreids in Ostreidae in the subclass Pteriomorphia. In this study, particularly, two transverse bands (stripes) appear at the anterior region of the acrosomal vesicle of this species, unlike two or three transverse bands (stripes) in C. gigas. It is assumed that differences in this acrosomal substructure are associated with the inability of fertilization between the genus Crassostrea and other genus species in Ostreidae. Therefore, we can use sperm ultrastructures and morphologies in the resolution of taxonomic relationships within the Ostreidae in the subclass Pteriomorphia. These spermatozoa, which contain several ultrastructures such as acrosomal vesicle, an axial rod in the sperm head part and four mitochondria and satellite fibres in the sperm midpiece, belong to the family Ostreidae in the subclass Pteriomorphia.

• Animal Systematics, Evolution and Diversity
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• v.16 no.2
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• pp.203-211
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• 2000

Partial mitochondrial 16S rDNA and COI gene were amplified using PCR and sequenced for four species of oysters in Korea. Phylogenetic relationships among them were inferred from their aligned sequences by neighbor-joining method. The sequence comparison data of two mitochondrial genes showed that the genetic distinction between two oyster genera (Crassostreo and Ostrea) was obvious. Phylogenetic analysis based on the nucleotide sequences and A+T percentage of two genes indicates that C. gigas and C. nippona strongly formed a sister group and then C. ariakensis was clustered with the clade although that based on amino acid sequences of COI gene by neighbor-joining method represented different phylogenetic tree.

• The Korean Journal of Quaternary Research
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• v.8 no.1
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• pp.33-42
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• 1994

The study area is filled up by alluvium which can be classified into lower and upper beds by the facies of deposits and their degree of weathering. The lower bed is not of marine but of fluvial. The upper bed is mainly composed of clay and silt or fine sand beds col-ored dark or dark gray which are of neritic or brackish yielding mollusca fossils. The oyster(Crassostrea ariakensis) obstained from the depth of 3m below the present sea level in the upper bed was dated at 4,100 110Y.B.P. and the veneridae(Meretrix lamarck) 1m height above the present delta plain in the old sand bar was dated at 1,700 85Y,B,P. It is therfore concluded that the study area a small kern col of terrestri-al basin prior to postglacial age had experienced the Holocene transgression. Consequently the study area is considered to have been progressively formed under neritic or brackish circumstance before 1,700Y.B.P.

• The Korean Journal of Malacology
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• v.25 no.1
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• pp.41-49
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• 2009

Random amplified polymorphic DNA (RAPD) marker and sequence analyses of the internal transcribed spacer (ITS) region of ribosomal DNA were used to assess phylogenetic relationships of four Korean oyster species. The average number of species-specific markers identified from five universal rice primers (URPs) by RAPD-PCR was 1.8 for Crassostrea gigas, 3.2 for C. nippona, 3.6 for C. ariakensis, and 4.6 for Ostrea denselamellosa. The length of the ITS (ITS1-5.8S-ITS2) region ranged from 1,001 to 1,206 bp (ITS1, 426-518 bp; 5.8S, 157 bp; and ITS2, 418-536 bp), while the GC content ranged from 55.5-61.1% (ITS1, 56.8-61.8%; 5.8S, 56-57.3%; and ITS2, 54.1-62.2%). A phylogenetic analysis of the oysters based on our RAPD, ITS1, and ITS2 sequence data revealed a close relationship between C. gigas and C. nippona and a distant relationship between the genera Crassostrea and Ostrea. Our results indicated that RAPD and ITS sequence analysis was a useful tool for the elucidation of phylogenetic relationships and for the selection of species-specific markers in Korean oysters.

• The Korean Journal of Malacology
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• v.25 no.2
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• pp.153-160
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• 2009

Pisidium (Neopisidium) coreanum is a freshwater snail and lives in spring water near mountain areas. Interestingly, this snail has been traditionally regarded as medicinal food, and thus has been used as folk remedies for healing broken bones. Recently, alpha classification on Pisidium (Neopisidium) coreanum through redescription has been conducted. However, not much attention has been made in beta classification. In this study, we performed the beta classification based on metallothionein (MT) genes found from various organisms. To this end, the complete cDNA sequences were obtained from the Expressed Sequence Tag (EST) sequencing project of Pisidium (Neopisidium) coreanum. The coding region (315 bp) encoded an amino acid sequence of 105 residues. The combined results from BLAST analyses, multiple sequence alignment and molecular phylogenetic study of Pc-MT gene indicate that Pisidium (Neopisidium) coreanum has similarity to freshwater bivalve such as Dreissena polymorpha (zebra mussel), Unio tumidus (swollen river mussel) and Crassostrea ariakensis (suminoe oyster).