• 한국수산과학회지
• /
• 제46권6호
• /
• pp.813-818
• /
• 2013

In order to understand the co-culture impact of the sea squirt Halocynthia roretzi on the Pacific oyster Crassostrea gigas, we examined the filtration rate of the sea squirt in relation of water temperature ($5-25^{\circ}C$) and body weight. The filtration rate increased in relation to body weight and water temperature, indicating a clear positive correlation with the two variables. Due to the clear positive correlation between filtration rates at each temperature groups for acceptable collinearity, each constants at regression equation was further analyzed for a unified model of filtration rate. Therefore the filtration rate of H. roretzi was estimated as: Fr (L/h/animal)=$(0.1956+0.0182T){\times}DW^{0.7978EXP(-0.0273T)}$ for water temperature in the range of $5-25^{\circ}C$. The estimated filtration rates of H. roretzi were higher than those of C. gigas in the winter season (water temperatures below $16^{\circ}C$) in condition of equal body weight. Our results indicate that H. roretzi may have an advantage over C. gigas in food competition during the winter season when the two species are co-cultured.

• 한국수산과학회지
• /
• 제44권4호
• /
• pp.366-371
• /
• 2011

The sea squirt Halocynthia roretzi is mainly cultured in Tongyeong, Southern coastal area of Korea. This study presents the physiological rates of respiration, excretion, feeding and assimilation efficiency of the sea squirt Halocynthia roretzi to analyze the SFG(scope for growth) and net growth efficiency, determined during 2007. Oxygen consumption and nitrogen excretion rates increased with a rise in temperature during the summer period whereas feeding rates decreased. The O:N ratio was high during winter(October to February). Assimilation efficiency showed an annual average of 75.4% during the experimental period, except during a period of elevated temperature in July to September(average $25^{\circ}C$). Net growth efficiency($K_2$) was 8.7 to 64.2% except for May to September, when temperature increased at the aquaculture farm. SFG was negative from May to September, reflecting high temperatures and low feeding rates during this period; its highest positive values occurred during winter.

• 한국발생생물학회지:발생과생식
• /
• 제15권4호
• /
• pp.359-364
• /
• 2011

The seven selected primers OPA-02, OPA-04, OPA-18, OPD-07, OPD-08, OPD-15 and OPD-16 were used to generate unique shared loci to each species and shared loci by the two species. The hierarchical dendrogram indicates three main branches: cluster 1 (RORETZI 01~RORETZI 11) and cluster 2 (HILGENDORF 12~HILGENDORF 22) from two geographic populations of ascidians, Halocynthia roretzi and H. hilgendorfi. The shortest genetic distance displaying significant molecular difference was between individuals' HILGENDORF no. 14~HILGENDORF no. 19 (genetic distance =0.008). Ultimately, individual no. 02 of the RORETZI ascidian was most distantly related to HILGENDORF no. 21 (genetic distance=0.781). These results demonstrate that the H. roretzi population is genetically different from the H. hilgendorfi population. From what has been said above, the potential of PCR analysis to identify diagnostic markers for the identification of two ascidian populations has been demonstrated. Generally speaking, using a variety of decamer primers, this PCR method has been applied to identify specific markers particular to line, species and geographical population, as well as genetic diversity/polymorphism in diverse species of organisms.

• 한국수산과학회지
• /
• 제46권5호
• /
• pp.575-581
• /
• 2013

We examined the effect of starvation on the occurrence of tunic softness to determine the cause of mass mortality of cultured Halocynthia roretzi (Drasche) in the Tongyeong region, Korea. In terms of the survival rate of H. roretzi and the occurrence rate of tunic softness, H. roretzi starved for 35 days at water temperatures of 8, 12, and $15^{\circ}C{\pm}0.5^{\circ}C$ (room temperature of $15^{\circ}C{\pm}1^{\circ}C$) did not exhibit tunic softness at water temperatures of either $8^{\circ}C$ or $12^{\circ}C$. for morphological changes, although the tunic of H. roretzi was shrunken and became visibly smaller with a darkening color in all experimental groups, as compared to the state prior to starvation, its tunics bulbs continuously. The ratio of RNA/DNA concentrations and protein contents for each of the tunic sections were lower in the starved group. Our results indicate that tunic softness is not related to feeding deficiency, as no histopathological symptoms were apparent in the digestive gland or tunic of H. roretzi due to starvation.

• 한국식품과학회지
• /
• 제28권5호
• /
• pp.910-915
• /
• 1996

본 연구는 우렁쉥이(Halocynthia roretzi)의 가공 및 저장 수단을 모색하기 위하여 냉동품으로서의 가능성과 동결저장 중 이에 수반되어 일어나는 흑변방지를 목적으로 실시하였으며, 흑변현상은 저장온도가 낮고, Polyethylene film으로 밀착포장한 것은 그렇지 않은 것보다 진행속도가 완만하였다. 식품첨가물 중 식염수와 구연산이 흑변방지 효과가 우수하였으며 3%식염수에 0.3% 구연산 함유용액을 조제하여 $3{\sim}5$분간 침지한 다음 수지 필름에 밀착포장하여 $-45^{\circ}C$에서 5시간동안 동결한 것을 $-20^{\circ}C$에서 저장한 것은 저장 200일까지도 색조 및 품질 변화가 거의 없었다.

• 한국어병학회지
• /
• 제26권1호
• /
• pp.31-38
• /
• 2013

The edible ascidian, Halocynthia roretzi is a commercially important fisheries resource in Korea. However, there have been outbreaks of mass mortality due to soft tunic syndrome. It was discovered recently that the cause of death is infection by a protozoan parasite Azumiobodo hoyamushi. Alamar blue assay and microscopic counting were used to estimate anti-protozoal effects of 20 drugs having different action mechanisms. Through comparison of alamar blue assay and microscopic counting, 6 drugs were found to be potential in protozoan-killing effects: amphotericin B, formalin, hydrogen peroxide, bithionol, benzalkonium chloride, bronopol (24hr-$EC_{50}{\leq}20{\mu}g/ml$). The preliminary data can be used as a basis to develop anti-protozoal agents against A. hoyamushi.

• 한국수산과학회지
• /
• 제45권5호
• /
• pp.480-485
• /
• 2012

The hemocytes of the tunicate Halocynthia roretzi are classified into six types based on their size, cellular form, and fine structure of the cytoplasmic granules: hyalinocytes, granulocytes, phagocytes, nephrocytes, morula cells, and multi-vacuole cells. Based on cell size, they are ordered multi-vacuole cells ($7.5{\mu}m$)>nephrocytes ($7.1{\mu}m$)>phagocytes ($6.8{\mu}m$)>granulocytes ($6.1{\mu}m$)>morula cells ($5.7{\mu}m$)>hyalinocytes ($5.4{\mu}m$). The proportion of hemocytes is ranked in the order multi-vacuole cells (54.8%)>nephrocytes (16.9%)>granulocytes (9.9%)>morula cells (8.8%)>phagocytes (6.1%)>hyalinocytes (3.5%).

• 한국식품과학회지
• /
• 제28권6호
• /
• pp.1021-1025
• /
• 1996

우렁쉥이의 저장성을 부여하기위한 가공수단으로서 동결저장에 대한 가능성을 검토하였다. 우렁쉥이의 동결저장을 시도하였던 바, 각부체로 동결하였을 때는 대형 빙결정에 의한 육조직의 손상, 해동후 드립유출량 과다, 색조의 퇴색 등으로 그 품질이 빈약한데 비하여 박신하여 동결한 것은 각부체로 동결한 것에 비하여 조직특성, 색깔, 수율, 드립량 등의 품질특성이 우수하였으나, 약 60일 이후에는 흑변현상이 나타나기 시작하여 품질이 저하되었으므로 장기간의 동결저장을 위하여는 혹변방지에 관한 연구가 병행되어야 할 것으로 생각된다.

• 한국발생생물학회지:발생과생식
• /
• 제25권4호
• /
• pp.299-303
• /
• 2021

The ascidian Halocynthia aurantium (sea peach), a marine invertebrate, belongs to the same genus of the phylum Chordata along with the ascidian Halocynthia roretzi (sea pineapple), which is one of the model animals in the field of developmental biology. The characteristics of development and reproduction of H. aurantium are not yet known in detail. In order to find out the spawning period of H. aurantium, we investigated development of the gonads during the annual reproductive cycle. Testis and ovary were both in the bisexual gonads (ovotestes) of H. aurantium, which is a hermaphrodite like H. roretzi. In H. aurantium, the right gonad was longer and slightly larger than the left gonad throughout the year. In each gonad, the number of the testis gonoducts was slightly higher than that of the ovary gonoducts. These features were similarly observed in H. roretzi. However, the number of the testis gonoducts and the ovary gonoducts in each gonad of H. aurantium was about half that of H. roretzi. The gonads of H. aurantium contracted during the winter and summer seasons. The gonads decreased to the smallest size around February, and then started to increase again in March. The gonads were most developed in September of the year. Therefore, it is estimated that the spawning of H. aurantium begins around this period.

• 환경생물
• /
• 제30권4호
• /
• pp.349-354
• /
• 2012

To evaluate the biological response of sea squirt Halocynthia roretzi with different body size to heavy metals and its suitability for ecotoxicity assays, the effects of Cr, Cu and Zn on its clearance and oxygen consumption rates were investigated. Clearance and oxygen consumption rates of H. roretzi with various body sizes were calculated at different metal concentrations. Both clearance and oxygen consumption rate were negatively correlated with body sizes. Clearance rate of H. roretzi decreased gradually with increasing concentration of heavy metal, the decreasing rate was in an order of Cr>Cu>Zn. The oxygen consumption rate first increased at low metal concentration (below $100{\mu}g\;L^{-1}$) and then decreased rapidly with increasing metal concentrations. The decreasing rate was in an order of Cu>Cr=Zn. There was a trend that the clearance rate and oxygen consumption rate decreased drastically under a concentration of $400{\mu}g\;L^{-1}$, and then decreased smoothly when the metal ion concentration increased continually. So the oxygen consumption and clearance rate at a concentration of $400{\mu}g\;L^{-1}$ Cu could be thought as a suitable biological tool for exotoxicology analysis.