• 한국수산과학회지
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• 제51권3호
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• pp.332-337
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• 2018

The Pacific cod Gadus macrocepahlus, lays demersal eggs and the hatching larvae rise toward the surface layer of the ocean to feed. The change in the specific gravity of eggs and larvae was investigated to examine their vertical distribution and movement in the water column. The specific gravities of fertilized eggs and various size classes of larvae were measured using a density gradient apparatus. In total, the instantaneous specific gravity of 146 eggs and 225 larvae were measured. To prevent any disturbance in the gradient water column due to larval movement, 0.004% MS222 was used for anesthesia. Due to their high specific gravity, eggs spawned were deposited over the sea-bed of the spawning ground. The specific gravity of hatching larvae decreased abruptly. However, Pacific cod larvae still had a comparatively high specific gravity at hatching ($1.03655{\pm}0.00146g/cm3$, n=4, mean SL=3.62 mm) and their specific gravities tended to decrease as they grew. The specific gravity stabilized 6 days after hatching ($1.02590{\pm}0.00212g/cm3$, n=15, mean SL=4.67 mm) and the cod larvae were eventually able to float in the water column.

• Environmental Analysis Health and Toxicology
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• 제17권1호
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• pp.1-6
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• 2002

Effects on nonylphenol (NP) treatment on early development of fertilized eggs and survival of larvae in olive flounder, Paralichthys olivaceus were investigated. Fertilized eggs and hatched larvae were exposed to aqueous solutions of NP at nominal concentrations of 50, 100, 150 and 200 $\mu\textrm{g}$/L. In the control I and II (methanol-carrier control) groups, the hatchability of fertilized eggs were 90.7$\pm$7.02 and 90.0$\pm$5.29％ (P <0.05), respectively. However, treatments of NP concentrations at 50, 100, 150 and 200 ug/L were reduced to 78.7$\pm$4.16, 46.0$\pm$9.17, 48.0$\pm$3.46 and 33.3$\pm$11.02% (P<0.05), respectively. The time to hatching of fertilized eggs was delayed in high-dose NP treatment groups rather than control groups. Fertilized eggs of NP immersed group could not hatch normally, and also vertebra of the larvae observed as abnormal shape. Cumulative mortality of hatched larvae after 26hr NP treatment was 38.3, 78.3, 88.3 and 100% in NP 50, 100, 150 and 200 ug/L treatment groups, respectively. Whereas, control I and II were 11.7, 16.7% (P<0.05). Hatched larvae showed most death at the embryonic development stage with abnormalities. These results suggest that NP treatment in fertilized eggs and larvae was inhibited as normally development for fertilized egg and growing of larvae.

• Environmental Analysis Health and Toxicology
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• 제17권1호
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• pp.13-19
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• 2002

Effects of Formalin treatment on embryogenesis and larvae growing in fertilized eggs and hatched larvae of olive flounder, Paralichthys alivaceus were investigated. Fertilized eggs and hatched larvae were exposed to aqueous solution with 100, 200, 400, 800 and 1,000 ppm of nominal formalin concentration. They were kept in sea water of 16, 18 and 22$^{\circ}C$, respectively. Survival rate and hatchability of fertilized eggs were high in control groups more than formalin treated groups in 16, 18 and 22$^{\circ}C$, respectively (P<0.05). A similar effect that survival rate of hatched larvae was also observed for control and treatment groups. On the other hand, fertilized eggs treated with 400 ppm formalin, were all death in kept in 22$^{\circ}C$. These results suggest that high-dose of formalin in fertilized eggs and hatched larvae in olive flounder, Paralichthys olivaceus was inhibited the normal embryogenesis for fertilized eggs and growing for hatched larvae. Also, these inhibited effects was promoted in higher temperature.

• Parasites, Hosts and Diseases
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• 제52권4호
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• pp.383-389
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• 2014

Anisakiasis, a human infection of Anisakis L3 larvae, is one of the common foodborne parasitic diseases in Korea. Studies on the identification of anisakid larvae have been performed in the country, but most of them have been focused on morphological identification of the larvae. In this study, we analyzed the molecular characteristics of 174 Anisakis type I larvae collected from 10 species of fish caught in 3 different sea areas in Korea. PCR-RFLP and sequence analyses of rDNA ITS and mtDNA cox1 revealed that the larvae showed interesting distribution patterns depending on fish species and geographical locations. Anisakis pegreffii was predominant in fish from the Yellow Sea and the South Sea. Meanwhile, both A. pegreffii and A. simplex sensu stricto (A. simplex s.str.) larvae were identified in fish from the East Sea, depending on fish species infected. These results suggested that A. pegreffii was primarily distributed in a diverse species of fish in 3 sea areas around Korea, but A. simplex s.str. was dominantly identified in Oncorhynchus spp. in the East Sea.

• 한국수산과학회지
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• 제44권2호
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• pp.162-166
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• 2011

The distribution and occurrence of Charybdis japonica larvae were investigated off Yeonpyong-do, Korea, in the Yellow Sea. C. japonica larvae were collected monthly at 15 stations from early June to late October in 2006 and 2007. At each station, a Bongo net with 303 and $505{\mu}m$ mesh was deployed once with a double oblique tow. No larvae were caught in June, in both years. Zoea I was predominant in late July in 2006 and early August in 2007, whereas Zoea I accounted for 84% of all larvae collected and no larval stages later than Zoea III were sampled. Megalopa were the most abundant larval stage at all stations in late August in both years. The timing of larval hatching of C. japonica may be related to that of phytoplankton blooms in the study area. The finding that Zoea I and Megalopa were predominant in the study are may indicate that C. charybdis larvae are carried by advection.

• 미생물학회지
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• 제9권2호
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• pp.61-68
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• 1971

Borrelina virus was inoculated into Hyphantrea cunea DRURY in the labolatory and in the field. The pathogenecity of Borrelina virus upon Bompyx mori L. and Dendrolinus spectabilis BUTLER, too, was examined with following results. 1) $10^8$/ml, $10^7$/ ml, $10^6$/ml concentration of nuclear-polyhedrosis virus was inoculated into the larvae of H.cunea at various ages. The corrected mortality of the larvae were 97.4%, 95.2%, 94.7% in the 3rd instar, and 88.6%, 73.6%, 62.5% in the 6th instar, respectively, with three different concentration of NPV. 2) The symptom of disease of the larvae appeared on 4days after inoculation and most of the larvae were dead within 18 days. 3) The youngest larvae treated with the highest concentration of NPV showed the highest mortality. With older larvae and lower concentriton treated, it appeared that the time needed for death grew longer, marking slower death curve. 4) When we sprayed NPV of $10^6$/ml concentration to H. cunea in the field, the mortality was 94.8% in the first year, 84.6% in the second year and 78.3% in third year. By this, we could admit the continuous effects of the pathogens for several years. 5) About the larvae of B. mori of 3rd and 5th instar and D.spectabilis of 3rd instar inoculated with $10^8$/ml concentration of inoclum, we could not see any pathogenic effects.

• 한국양봉학회지
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• 제34권2호
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• pp.131-136
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• 2019

Recently, number of honeybees (Apis mellifera) has visibly decreased because they are vulnerable to some diseases like American foulbrood disease. American foulbrood disease, which is caused by Paenibacillus larvae, is emerged as great cause of decrease in number of honeybees. After antibiotic-resistant strain emerged, it is now more difficult to treat those pathogens successfully. Researches on finding alternative antibacterial compound are ongoing. In this study, we examined the antibacterial effect of honokiol on P. larvae. Honokiol showed great antibacterial effect with minimum inhibitory concentration of 12.5 ㎍/mL and minimum bactericidal concentration of 50 ㎍/mL. An agar diffusion test also confirmed the anti-Paenibacillus larvae activity of honokiol with an inhibitory zone of 9±0.5 mm. Since honokiol is known to interact membrane of some bacteria, we measured 260 nm absorbing particles, which could be induced by leakage of cells, and confirmed that the leakage of P. larvae occurred in dose-dependent manners. However, result of crystal violet assay suggested that honokiol has only mild anti-biofilm formation effect on P. larvae, which means honokiol controls the bacteria by inducing the bursting of membrane. Finally, an additive effect of honokiol with tetracycline and terramycin was found using a checkerboard assay with a fractional inhibitory concentration index value of 0.5.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2022년도 추계학술대회
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• pp.115-115
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• 2022

The Food and Agriculture Organization (FAO) has been estimating the potential of insects as human food and animal feed for convincing food security since 2010. On account of this reason, Tenebrio molitor larvae have been gaining considerable attention as an alternative protein source for various foods. However, consumers do not prefer them because of their disgusting appearance. Therefore, it is necessary to develop a method that improve their appearance as to lead to T. molitor larvae consumption. In this study, T. molitor larvae which is prepared for optimally sampling conditions (shade drying, 30 min boiling after hot air drying, 30 min steaming after hot air drying), were cultured with Cordyceps militaris mycelia, and measured growth and density of mycelial. Also analyzed the cordycepin and adenosine content compared with commercial C. militaris. As a result, T. molitor larvae cultivated with C. militaris mycelia showed the highest cordycepin content (13.75 mg/g) was observed in optimal sampling conditions (shade drying). Therefore, we report that the methods which T. molitor larvae cultivated with C. militaris mycelia not only improve their appearance but also increase cordycepin content, which can be contributed to lead T. molitor larvae consumption.

• 한국해양학회지
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• 제4권1호
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• pp.36-48
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• 1969

The larvae of Mytilus coruscus were grown at the room temperature of approximately 15.1C under several different sulture conditions, i.e., salinity, population of the larvae, density and kind of food organisms, etc. (1) The egg of Mytilus coruscus obtained in the laboratory measured about 73.0${\mu}$ in diameter. The embryos gradually developed into larvae up to 179.0${\mu}$ shell length with the shell height of 135.9${\mu}$ even in the absence of the algal food. Beyond this size, however, the growth of larvae was considerably retarded, indicating that the better growth could be expected if the food began to be fed four days after spawning. (2) The larvae began settling upon reaching 281.4${\mu}$ to 310.9${\mu}$ in shell length or 264.3${\mu}$ to 301.9${\mu}$ in shell height. When the shell length reaches 322.6${\mu}$ to 337.1${\mu}$, the shell height also reaches about the same, i.e., 321.5${\mu}$ to 346.2${\mu}$. (3) Daily rate of food consumption was determined by the size of the larvae and the species of the algal food. Regardless of the species of food given, the rage of food consumption remained almost the same until the larva reached the straight-hinge stage, and marked variations were found as the larvae grew larger. Daily rate of food consumption was shown as follow; Chaetoceros calcitrans : Y=2.99167e$\^$0.000018243x$\^$2// Cyclotella nana : Y=3.00324e$\^$0.000015481x$\^$2// Monochrysis lutheri : Y=3.000056e$\^$0.000014485$\^$2// (4) Suitable amount of the food to be given was about five times of the consumed food by Mytilus coruscus. (5) When the numbers of the larvae was higher than ten per milliliter, the growth was significantly retarded. (6) Monochrysis lutheri and Cyclotella nana were much better than Chaetoceros calcitrans as the food of Mytilus coruscus, and even the same food organism showed some difference with the age of the organism. (7) Sea water of higher salinity showed the better result in the growth of the larvae and the water with the specific gravity of 1.020 or below was dangerous for the larvae. (8) The mean growth of the larvae of Mytilus coruscus under lavorable condition was shown as follows: shell length 121.8${\mu}$ to 179.0${\mu}$ : Y=119.18+7.42X 196.7${\mu}$ to 322.6${\mu}$ : Y=203.144+7.687X 322.6${\mu}$ to 985.1${\mu}$ : Y=302.5978+11.8356X shell height 86.3${\mu}$ to 135.9${\mu}$ : Y=86.22+6.40X 158.1${\mu}$ to 321.5${\mu}$ : Y=162.998+10.027X 321.5${\mu}$ to 1,215.4${\mu}$ : Y=309.3701+16.258X Relationships between the shell length and shell height were shown as follows: shell length 121.8${\mu}$ to 179.0 : Y=0.83726X-15.79165 196.7${\mu}$ to 322.6 : Y=1.29909X-100.58610 322.6${\mu}$ to 985.1${\mu}$ : Y=1.3536X-101.6806

• Animal cells and systems
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• 제2권2호
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• pp.187-193
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• 1998

The four zoeal stages of Alpheus brevicristatus De Haan, 1849 are described and illustrated in detail from larvae roared in the laboratory. The larvae of A. brevicristatus was compared with those of the other Alpheus and a key to the first zoeal larvae of three Korean Alpheus species is provided.