갯벌의 건강 수준에 대한 평가는 갯벌에 서식하는 생물의 건강에 의해 평가될 수 있다. 생체지 표유전자의 발현 분석을 통하여 갯벌에 서식하는 생물의 건강 수준을 평가할 수 있다. 본 연구 의 목적은 heat shock protein 70 (Hsp70), heat shock protein 90 (Hsp90), glutathione S-transferases (GST) 및 thioredoxin (TRX)과 같은 생체지표유전자를 이용하여 서해안 갯벌의 건강을 평가하는 것이다. 이들 유전자는 스트레스, 면역 및 항산화 관련한 유전자들로서 이들 유전자의 발현을 통해 생물의 건강 정도를 관찰하는 데 사용할 수 있다. 본 연구에서는 서해안의 8개 정점에서 바지락(Ruditapes philippinarum)을 수집했다. 유전자의 발현은 RT-qPCR 방법으로 분석하였다. 연구 결과 Hsp70, Hsp90, GST 및 TRX 유전자들의 발현이 8개 정점에서 차별적으로 발현되는 것으로 나타났다. 특히, Hsp90 및 GST의 발현 또는 Hsp70 및 TRX의 발현은 유사하였다. 이것 은 각 유전자에 특이적으로 반응하는 물질이 존재하는 것으로 생각된다. 따라서 이화학적 분석 결과에 근거하여 분석에 적합한 유전자를 선택할 수 있다고 생각한다. 이 결과는 Hsp70, Hsp90, GST 및 TRX 유전자는 갯벌의 건강을 평가하기 위한 생체지표유전자로서의 역할을 수행함을 시사한다.

본 연구는 2000년 12월에서 2007년 5월 사이 태안조간대에서 참굴(Crassostrea gigas)과 바지락 (Ruditapes phillippinarum)의 먹이원을 평가하기 위해서 굴과 바지락의 소화기관 내용물 속의 식물플랑크톤의 종 조성과 더블어 수증과 퇴적물의 식물플랑크톤의 군집조성을 격월로 조사했다. 조사기간 동안 수온은 7℃에서 23℃로, 염분은 34PSU에서 35PSU로, 각각 관찰되었다. 수중의

여름철 고수온기와 집중강우로 인하여 염분의 급격히 감소하는 시기에 바지락의 일간먹이밀도 감소량, 여수율, 소화율을 조사하였다. 실험결과 바지락은 수온과 염분에 의하여 일간먹이밀도 감소량, 여수율, 소화율이 영향을 받는 것으로 나타났다. 수온의 경우 소형그룹의 27℃에서 각각 5.8× 104 cells ml-1, 16.96 liter hr-1 g-1, 12.04× 107 cel

바지락포자층 Perkinsus는 Apicomplexa 문에 속하는 기생성 원생동물로서 유럽에서는 바지락의 대량폐사 원인 생물로 잘 알려져 있으며 우리나라에서도 90년대 초반부터 나타나고 있는 바지락 폐사의 원인생물로 추정되고 있다. 이 연구는 우리나라 바지락포자충 감염분포 조사의 일환으로 제주 연안에 서식하는 바지락의 바지락포자충 감염 현황과 감염도, 조직병리학적 현상, 유주자 형성 그리고 서식지의 퇴적물 조성에 따른 감염 특성을 조사하기 위하여 실시되

The PCR analysis was performed on DNA samples extracted from a total of 20 individuals using six oligonucleotides primers. The author accomplished clustering analyses to reveal the Euclidean genetic distances among four clam populations from Gochang, Seocheon, Taean and Anmyeon of the Korean peninsula. The oligonucleotides primer OPA-08 generated 5 unique loci to each population, approximately 550 bp and 600 bp, respectively, in the MCS population. Especially, the primer OPA-20 generated 15 unique loci to each population, which were identifying each population, approximately 400 bp, 750 bp and 800 bp, in the MCT population. Individuals from MCG clam population (0.637±0.227) exhibited higher bandsharing values than did individuals from MCG clam population (0.402±0.115) (P<0.05). The dendrogram obtained by the six oligonucleotides primers indicates four genetic clusters: cluster 1 (MCG 01, 02, 04 and 05), cluster 2 (MCS 06, 07, 08, 09 and 10), cluster 3 (MCT 11, 12, 13, 14 and 15) and cluster 4 (MCA 16, 17, 18, 19, 20 and MCG 03). Among the twenty clam individuals, the shortest genetic distance that displayed significant molecular differences was between individuals 14 and 15 from the MCT population (genetic distance = 0.094), while the longest genetic distance among the twenty individuals that displayed significant molecular differences was between individuals MCG no. 01 and MCG no. 02 (genetic distance = 0.687). Comparatively, individuals of MCS clam population were fairly closely related to that of MCT clam population, as shown in the hierarchical dendrogram of Euclidean genetic distances.

The author has investigated four Manila clam populations of the family Veneridae, belonging to the order Veneroida. The clam is also indigenous to some parts of the sandy regions of the West Sea in the Korean Peninsula, as well as in several areas in China. Clams are the most popular marine products in Korea because of their taste and nutritional value, and Koreans consume them in large quantities. However, in spite of their economic and scientific consequences, a little information currently exist regarding the physiological and ecological levels only of clam species in Korea. This study attempt is to elucidate the genetic distances within and between clam populations from the West Sea. Four populations of Manila clam (R. philippinarum) were obtained in adjacent district to the West Sea in Korea. Four populations of clam muscle was collected in sterile tubes, placed on ice immediately, and stored under refrigeration until needed. Genomic DNA was extracted and purified under the conditions described previously (Yoon and Kim, 2004). The degree of variability was calculated by use of the Dice coefficient (F), which is given by the formula: F=2 nab / (na+nb), where nab is the number of bands shared between the samples a and b, na is the total number of bands for sample a and nb is the total number of bands for sample b (Jeffreys and Morton, 1987; Yoke-Kqueen and Radu, 2006). Euclidean genetic distances within- and between-species were also calculated by complete linkage method with the support of the hierarchical dendrogram program Systat version 10. The genomic DNA isolated from four Manila clams populations in the West Sea, were amplified several times by PCR reaction. The dendrogram obtained by the six oligonucleotides primers indicates three genetic clusters. The hierarchical dendrogram indicates four main branches: cluster 1 (GOCHANG 01, 02, 04 and 05), cluster 2 (SEOCHEON 06, 07, 08, 09 and 10), cluster 3 (TAEAN 11, 12, 13, 14 and 15) and cluster 4 (ANMYEON 16, 17, 18, 19, 20 and GOCHANG 03). Multiple comparisons of average bandsharing values among Manila clam populations from four sections were generated according to the bandsharing values and similarity matrix. Ultimately, individuals from SEOCHEON clam population (0.637±0.227) exhibited higher bandsharing values than did individuals from GOCHANG clam population (0.402±0.115) (P<0.05).

The reproductive life-history of molluscs can be divided into gonochorism and hermaphroditism, while hermaphroditism is further classified into simultaneous (synchronous or functional) and sequential (asynchronous) (Heller 1993 Gosling 2004). Approximately 40% of the 5600 mollusc genera are either simultaneous or sequential hermaphrodites. Hermaphroditism occurs in 100% of the Solenogastres, 99% of the Opisthobranchia, 100% of the Pulmonata, 3% of the Prosobranchia and 9% of the Bivalvia. Simultaneous hermaphroditism is the simultaneous release of eggs and sperm by one organism during the same season. Sequential hermaphroditism is the function of an organism first as one sex, then as another (Heller 1993). This study investigated the sex of Manila clam, Ruditapes philippinarum by verifying changes in sex ratio (F:M) with size and sex reversal stages. Adult one-year-old (11 months; SL 36.75±3.0 mm) R. philippinarum were used for sex reversal identification. Each individual was tagged on its shell prior to being reared in the wild for reproductive analysis, and sex was confirmed using the germ cell aspiration (GCA) method. Sex ratio (F:M) at the commencement of the study (June 2009) was 1:1.23, but changed to 1:0.87 by the end (July 2010). Overall sex reversal rate was 19.0%. Specifically, male to female sex reversal ratio was 21.05%, which was higher than the female to male sex reversal ratio of 12.9%. Based on our results, R. philippinarum has been confirmed to possess a sequentially hermaphroditic life-history.

R. Philippinarum is dioecious and oviparous. In the early vitellogenic oocyte, the Golgi apparatus and mitochondria present in the perinuclear region are involved in the formation of lipid droplets and in lipid granule formation. In the late vitellogenic oocyte, the endoplasmic reticulum, mitochondria in the cytoplasm are involved in the formation of proteid yolk granules. At this time, exogenous lipid granular substance and glycogen particles in the germinal epithelium are passed into the ooplasm of oocyte through the microvilli of the vitelline envelope. Ripe oocytes are about 55-60 m in diameter. The spawning period was once a year between early June and early October, and the main spawning occurred between July and August when seawater temperature was approximately 20 C. The reproductive cycle of this species can be categorized into five successive stages: early active stage (February to March), late active stage (April to May), ripe stage (April to August), partially spawned stage (June to October), and spent/inactive stage (August to March). Gonad developmental phases by histological qualitative analysis showed similar results with those of quantitative image analysis.