• The Korean Journal of Zoology
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• v.33 no.2
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• pp.200-216
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• 1990

The complete larval development of Scopimera bitympana Shen was descdbed and mustrated from the larvae reared in the lahoratory. S bItympana had five, or occasionally six, zoeal and one megalopal stages. At $25^{\circ}C$, the megalopa and the first crab instar were attained in 24 and 38 days (31 and 48 days in six zoeal series) after hatching respectively. S.bitympana zoeae can be distinguished from other described zoeae in the genus by the toothed carapace spines and the telson with a dorsal and two ventral spines. Megalopa of this species can be distinguished from other ScopimeTa spedes by the feature of carapace. Other minor morphological features of S. bitympana larvae are compared to the previous descripdons of larvae of the genus and the morphological differences are briefly discussed.

• The Korean Journal of Malacology
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• v.28 no.2
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• pp.145-156
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• 2012

Larval development of the Manila clam Ruditapes philippinarum reared in an indoor tank system was examined in this study using light microscope and scanning electron microscope. To induce spawning and subsequent larval development, clams were collected from the intertidal zone at Gim-nyeong harbor in Jeju Island in August 2011. After 2 days of rearing in the tank, all Manila clams spawned in the midnight. Non-feeding trochophore larvae appeared 7hrsafter fertilization and the first D-shape larvae could be observed at 19 hrs. Twenty one days after fertilization the pediveliger larvae crawling on the bottom of the tank with well-developed foot were observed. Histology indicated that all the clams used in this study were in the ripe stage prior to spawning and the gonad-somatic index (GSI), a ratio of the egg mass to the tissue weight, of the ripe female measured by ELISA was 28.6%. The GSI of female clam declined to 17.3% after the massive spawning in the tank, suggesting that Manila clam discharged 40% of the total eggs during the first spawning event. In conclusion, spawning and subsequent larval development of Manila clam was successfully carried out in this study using an indoor tank system, and the information obtained in the present study could be useful in future Manila clam hatchery development.

• The Korean Journal of Malacology
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• v.19 no.1
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• pp.33-40
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• 2003

To obtain the basic information on culture conditions for the larvae of Saxidomus purpuratus, experiments were conducted on the population from southern coast for (1) the success in fertilization and development from artificial fertilization among different months of a year, (2) the viability of sperms after exposure to seawater, (3) and the effects of temperature, salinity, and food organism on the survival and growth of larvae. Gametes obtained from dissection showed high rate of fertilization at all months. But the rate of development was higher only May-July. Developmental success seemed to be related with the quality of eggs at the time of fertilization. Developmental times for 2-cell, 4-cell, 8-cell, blastula, trochophore larva, and veliger larva at 20$^{\circ}C$ were 1.5, 2, 4, 18, 24, and 32 hr, respectively. Sperms could survive for more than 8 hr, however, actively swimming sperms could be found within 1 hr after exposure to seawater. It is recommended that sperms should be used for fertilization as soon as possible when they are exposed to seawater. At temperature of 35$^{\circ}C$, all the larvae died during 48 hr. Larval survival decreased when salinity was either lower than 20 psu or higher than 40 psu, and was 0% when salinity was 10 psu. Optimal range of temperature and salinity for rearing larvae of S. purpuratus were 20-25$^{\circ}C$ and 20-40 psu, respectively. Larvae grew from 111.5 to 235.3 ${\mu}$m during 21 days. Larvae fed mixed diets grew faster than unialgal diets. The fastest growth was observed when larvae were fed on the mixture of Isochrysis galbana and Nannochloris oculata.

• International Journal of Industrial Entomology and Biomaterials
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• v.33 no.2
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• pp.50-53
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• 2016

The size of head capsule is one of the most important factors for identifying developmental stage. In order to understand the developmental characteristics of the butterfly Atrophaneura alcinous, we examined fluctuations in larval head capsule size under three different temperature conditions (20, 25, and $30^{\circ}C$) and 60% humidity. As a result, larvae developed to the fifth instar at all three temperatures. The head capsule size of larvae tended to be larger at the lowest temperature and smaller at the highest temperature. The development rate showed a regular change, consistent with Dyar's rule regarding head capsule size development. Furthermore, the development of head capsule size was found to correspond to a second degree polynomial regression better than to a linear regression. On the basis of these results, it would appear to be possible to perform an accurate assessment of instar status during the development of A. alcinous.

• Molecules and Cells
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• v.38 no.3
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• pp.236-242
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• 2015

Intake of caffeine during pregnancy can cause retardation of fetal development. Although the significant influence of caffeine on animal development is widely recognized, much remains unknown about its mode of action because of its pleiotropic effects on living organisms. In the present study, by using Caenorhabditis elegans as a model organism, the effects of caffeine on development were examined. Brood size, embryonic lethality, and percent larval development were investigated, and caffeine was found to inhibit the development of C. elegans at most of the stages in a dosage-dependent fashion. Upon treatment with 30 mM caffeine, the majority ($86.1{\pm}3.4%$) of the L1 larvae were irreversibly arrested without further development. In contrast, many of the late-stage larvae survived and grew to adults when exposed to the same 30 mM caffeine. These results suggest that early-stage larvae are more susceptible to caffeine than later-stage larvae. To understand the metabolic responses to caffeine treatment, the levels of expression of cytochrome P450 (cyp) genes were examined with or without caffeine treatment using comparative microarray, and it was found that the expression of 24 cyp genes was increased by more than 2-fold (p < 0.05). Among them, induction of the cyp-35A gene family was the most prominent. Interestingly, depletion of the cyp-35A family genes one-by-one or in combination through RNA interference resulted in partial rescue from early larval developmental arrest caused by caffeine treatment, suggesting that the high-level induction of cyp-35A family genes can be fatal to the development of early-stage larvae.

• International Journal of Industrial Entomology and Biomaterials
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• v.29 no.2
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• pp.153-161
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• 2014

The aim of this study is to investigate the effects of ambient thermal environments on the development of swallowtail butterflies (Sericinus montela Gray). Developmental durations and survival rates of S. montela were examined at two crucial developmental stages, embryonic and larval development, at varying temperatures ranging from $15^{\circ}C$ to $35^{\circ}C$. As expected, our results indicated that increasing temperatures decreased the developmental duration and survival rate of the eggs. However, the larvae and pupae showed maximum survival rates at $20.0^{\circ}C$ and $25.0^{\circ}C$, and the represented durations were similar to those of the eggs. Larval development was stage-specific, revealing that the fourth and fifth instars at the later stages were more susceptible to temperature variation. When considering both parameters, the optimal development of S. montela occurred within the temperature range of $20.0-25.0^{\circ}C$. The lower threshold for the complete development of S. montela from eggs to eclosion of adults was calculated at $10.6^{\circ}C$ by linear regression analysis. The estimated value is similar to that of other endemic insects distributed in temperate climate zones, which indicates that S. montela belongs to a small group of swallowtails adjusted to low ambient temperatures. From the results, we predict that the full development of S. montela could be achieved within the temperature range of $17.5-30.0^{\circ}C$. Embryonic development ceased at both test temperature extremes, and no further larval development proceeded after the third instar at $35.0^{\circ}C$. These results suggest that embryogenesis can be significantly influenced by slight variations in the ambient thermal environment that fall below the optimal range.

• Animal Systematics, Evolution and Diversity
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• v.9 no.2
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• pp.69-86
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• 1993

The larval stages of Hemigrapsus sanguineus were reared in the laboratory and described with illustrative figures. Five zoeal and one megalopal stages were found in the complete larval development. At 25^{\circ}C.$, the megalopa and the first crab instar were attained in 18 and 31 days after hatching, respectively. The first zoeal larva of H. sanguineus showed the characteristics ~ h i c h coincide with those of the same genus by bearing lateral spines on carapace, B-types of telson and antenna, 1 +5 setae on the endopod of maxillule, and 2 + 2 setae on the endopod of maxilla. Morphological features of H. sanguineus larvae were compared to the previous descriptions of larvae of the same genus and morphological differences among them were discussed.

• Korean journal of applied entomology
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• v.31 no.4
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• pp.371-378
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• 1992

The ecdysteroid titers of representive developmental stages of the blackblow fly, Phormia regina, were determined by radioimmunoassay and the effect of ecdysteroid on the oocyte maturation was investigated. Prior to every molts ecdysteroid levels began to increase sharply, suggesting ecdysteroid was the major component for egg-larval, larval-larval, and larval-pupal transformation. A difference in the levels of ecdysteroid between male and female was ob¬served during adult life span. Following the protein meal, ecdysteroid in the females increased rapidly to a maximum at 96 hr of age when terminal oocyte fully matured. Effect of ecdysteroid on oocyte development was determined for control and ecdysone-treated female flies after the liver-feeding. The growth of oocyte in the flies treated by $\mu$g of ecdysone, along with the control flies, was not facilitated. When the flies treated by 5 $\mu$g of ecdysone, however, duration of oocyte maturation was shorter than those of other two groups. This can be suggested that oocyte development in P. regina is due to the critical level of ecdysone.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.45 no.4
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• pp.251-259
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• 2009

Swimming crabs, Portunus trituberculatus(Miers) are commercially important off the coasts of Korea, Japan and China. Harvest of swimming crabs has been fluctuated along their distribution ranges. Fluctuations in the interannual harvest of swimming crabs may be correlated with the survival rate during the larval period. The survival rates, intermolt periods, and growth of larval swimming crabs were investigated in the laboratory. Larval swimming crabs are released and undergo development from April to August off the western coast of Korea in the Yellow Sea. Sea surface temperatures off the western coast of Korea during the larval season were used for the laboratory experiments, and ranged from 22 to 26${^{\circ}C}$. Larvae were individually cultured at four different temperatures, 22${^{\circ}C}$, 24${^{\circ}C}$, 26${^{\circ}C}$, and 28${^{\circ}C}$. Zoea molted to megalopa at all temperatures and developed to the first crab stage at 24${^{\circ}C}$, 26${^{\circ}C}$, and 28${^{\circ}C}$. Survival rates from zoea I to the first crab stage increased with increasing temperatures. Intermolt period and the growth rate of the mean carapace length were inversely correlated with temperature. Our research helps understand the changes in survival rate and growth of larval swimming crabs resulting from changing oceanic temperatures. Further, our study suggests that the fluctuations in fishery harvest of swimming crabs off the coast of Korea may be related to changes in larval survival affected by changing ocean conditions.

• Animal cells and systems
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• v.1 no.1
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• pp.31-42
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• 1997

The larval stages of Pilumnopeus granulata and the megalopal stage of Pilumnus minutus are described in detail. Comparisons are made with the known larvae of other species of the pilumnid genera, and the provisional key is provided for the pilumnid zoeae. The brachyuran genera Heteropanope, Heteropilumnus, Actumnus, Pilumonopeus, Pilumnus, Parapilumnus, and Benthopanpe are clearly classified on the basis of the zoeal characteristics, such as the lateral carapace spine, dorsal carapace spine, maxillule, and abominal lateral knobs.