돌기해삼 Apostichopus japonicus는 주요 양식 대상 무척추동물로서 우리나라 연안 해역에 서 식하고 있다. 본 연구는 방류 방법에 따른 단기간의 생리학적 스트레스 정도를 평가하기 위하 여 heat shock protein 90 (HSP90) 유전자의 발현 변화를 실시간 정량적 중합효소연쇄반응법 으로 조사하였다. 어린 돌기해삼을 비닐봉지에 산소 포장하여 30분간 수송하거나 방류 해역의 간조기에 1시간 공기 중에 노출된 실험군의 HSP90 유전자 발현은 대조군의 HSP90 유전자 발현에 비하여 통계학적으로 유의미하게 증가하였다(수송 후 실험군 p=0.001; 간조기 실험군 p=0.032). 어린 돌기해삼을 방류 후 6시간까지 분석한 결과, 선상에서 씨뿌림 방식으로 방류된 6시간째의 개체 및 호스를 통과하여 수중으로 방류된 2~6시간째의 HSP90 유전자 발현율은 대 조군에 비하여 약간 감소하는 경향을 보였다(씨뿌림 실험군 p=0.069; 호스 방류군 p=0.093). 한 편, 잠수부에 의해 수중에서 방류된 어린 돌기해삼은 방류 후 시간이 경과할수록 HSP90 유전 자 발현율은 증가하는 패턴이 관찰되었다(p=0.061). 이상의 결과는 방류된 어린 돌기해삼의 단기간 스트레스 반응 연구와 효과적인 방류 방법의 개발에 HSP90 유전자 발현이 유용하게 사용될 수 있음을 시사한다.

The objective of this study was to investigate the growth rate and the optimal stocking density of sea cucumbers. Grow-out was studied in situ by conducting a follow-up survey using visible implant elastomer (VIE) tags. The rearing systems were made of polypropylene pipe for the frames and netting. The experiment ran for 70 days near Yeosu, Korea in the water depth of about 7 m. A total of 576 sea cucumbers which have three groups of body sizes (small: 5.15, medium: 12.34 and large: 23.26 g) were used. The five groups of stocking densities (150, 300, 450, 600 and 850 g/m2) in rearing system for sea cucumber were considered. Sea cucumbers were fed a mixed diet (mud, mineral, fish meal, etc.). The feed was supplied to 10% of their body wet weight once every 7 days. The survival rate (73%) of sea cucumber in 850 g/m2 was lower than those of other density groups (150 g/m2: 89%, 300 g/m2: 84%, 450 g/m2: 78% and 600 g/m2: 86%). The survival rate of medium size group was higher than those of small and large groups regardless of the density (P<0.05). Most of density groups have no significant difference except for 850 g/m2 (P>0.05). The growth rate of small size group (0.63% day-1) was higher than those of medium (0.38% day-1) and large (0.34% day-1) group regardless of the density (P<0.05). The threshold water temperature was 11.0°C for sea cucumber growth in winter season.

The Apostichopus japonicus is an important species in some Asia countries including Korea, China and Japan. The purpose of the present study was to investigate the differential gene expression of heat shock protein90 (Hsp90) and ferritin as a biomarker for the thermal stress during water temperature rising in the sea cucumber, A. japonicus. The A. japonicus (1.4 g) was cultured in incubator of separate temperature (15°C, 20°C, 25°C and 30°C) for each 0, 3, 6, 12, 24, 48 hours. The mRNA expression levels of Hsp90 and ferritin were examined using RT-PCR assay. Results showed that, the expression of Hsp90 mRNA was not significantly changed at 15°C. The expression of Hsp90 mRNA was significantly increased at high temperature such as 20°C and 25°C. Furthermore, Hsp90 mRNA was early increased at 25°C than 20°C. The ferritin mRNA was similar expression pattern with Hsp90. But, Hsp90 mRNA was more sensitive than ferritin mRNA at high thermal stress. These results indicate that Hsp90 and ferritin mRNAs were involved in the temperature changes response and may be play an important role in mediating the thermal stress in A. japonicas.

The sea cucumber, Apostichopus japonicus, is becoming an important aquaculture species in China, Japan and Korea. The purpose of this study is to evaluate the biological performance of a tubular type of subsurface cage for sea cucumber grow-out by in-situ tests. The cage structure was constructed of PP (polypropylene) frames and PP tubes (ø130 mm×24 pieces). A set of tests were conducted at a depth of 15 m near Seosaeng, Ulsan, Korea for 295 days (23 July, 2012 to 13 May, 2013). A total of 155 sea cucumbers were used and fed a mixed diet containing mud, mineral, wheat, fish meal, etc (3% of their body weight). At the end of the experiments, sea cucumber showed a higher survival rate in feed shelter (77.14%) rather than no feed shelter (64.71%). The specific growth rate (SGR) of sea cucumbers in feed condition (0.04% day－1) was higher than that of no feed culture animals (－0.49% day－1) during total experimental periods. The result was able to find a no significance difference in survival rate but a significance difference in SGR under feed and no feed treatments.