• The Korean Journal of Malacology
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• v.25 no.1
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• pp.35-40
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• 2009

The trumpet shell Charonia sauliae is an endangered and valuable species with potential for aquaculture. For artificial propagation of C. sauliae, the effects of three different food microalgae on the development, growth, and survival rate of the larvae and spat were investigated. For the larval feeding experiments, we utilized six microalgae species as food sources, namely Pavlova lutheri, Tetraselmis suecica, Nannochloris oculata, Isochrysis galbana, Chaetoceros calcitrans, and Phaeodactylum tricornutum; for the larval and spat growth and survival experiments, we utilized T. suecica, C. calcitrans, and P. tricornutum. The results showed that the temporal digestion index (TDI) for the veliger larvae was significantly different for C. sauliae fed the different microalgae species (p < 0.05), that the T. suecica, C. calcitrans, and P. tricornutum cultivars were better suited for larval consumption (p < 0.05), and that the growth and survival of the larvae and spat were significantly influenced by food type, specifically P. tricornutum (p < 0.05). Further research is needed to evaluate the effects of other microalgae species, different algal concentrations, and biochemical composition on the growth and survival of C. sauliae.

• Journal of Aquaculture
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• v.17 no.1
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• pp.58-61
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• 2004

Larvae of Pandalus gracilis were reared in the laboratory under controlled conditions (salinity, 32.5∼34.5; photo-periods, 12L: 12D). The experiments were designed to examine effects of temperature (10 and 2$0^{\circ}C$) on larval development, survival, intermolt period and larval growth. The higher survival rate was obtained at 2$0^{\circ}C$ than at 1$0^{\circ}C$ and larvae reached later stages at 2$0^{\circ}C$. Intermolt period increased significantly with increasing of instar number and was longer at 1$0^{\circ}C$ than at 2$0^{\circ}C$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.25 no.6
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• pp.495-500
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• 1992

The relationship between distribution of eggs and larvae of anchovy, Engraulis japonica, and environmental factors were studied using the data on the ichthyoplankton and zooplankton sampled vertically by net, and water temperature and salinity observed by CTB in the eastern waters of Korea in every two month in 1985. Anchovy eggs and larvae were occurred in June and August. They distributed in the warm water current which was high temperature and salinity in June. Egg and larval distribution area were moved to the offshore in August. It is likely that distribution of anchovy eggs and larval in June significantly correlate with hydroconditions in the eastern waters of Korea.

• Fisheries and Aquatic Sciences
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• v.13 no.4
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• pp.308-314
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• 2010

Larvae of Palaemon serrifer were reared in the laboratory under three different temperature regimes ($15^{\circ}C$, $20^{\circ}C$, $25^{\circ}C$) to study the effects of rearing temperature on larval survival and growth, as well as other traits such as embryo volume, number of embryos (fecundity), incubation period, development. Mode and development period. Growth pattern was analyzed by measuring the molt increment and intermolt period. The intermolt period consistently increased with size and instar number and was shortest at $25^{\circ}C$. However, molt increments generally decreased with instar number. Number of embryos varied from 552 to 1355. The relationship between the number of embryos and carapace length was expressed by the equation (fecundity) y=2.7744x+0.208 ($R^2$=0.7961). Egg volume was a primary factor affecting other life-history traits. Egg volume was $0.078\;m^3$, which is relatively small thus embryos exhibited a relatively short incubation period and a comparatively short development period, and the nutritional mode was planktotrophic. Brood production was followed by a fast parturitional pattern. Most ovigerous females had mature ovaries when the parturial molt occurred soon after eclosion.

• Korean Journal of Ichthyology
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• v.27 no.2
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• pp.104-115
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• 2015

The species composition of larval fish assemblages in the Nakdong River estuary, Korea, was determined using monthly samples collected between September 2010 and August 2011 at two stations. A total of forty three larval species were collected during the study. Among forty three taxa of fish larvae, summer gobies, Clupea pallasii, Engraulis japonicus, spring gobies, Konosirus punctatus, winter gobies, Sardinops melanostictus, Coilia nasus were dominant taxa, and these eight taxa accounted for 95.0% in the total number of individuals. Species composition and abundance varied greatly spatio-temprally showing the peak abundances of fish larvae in August 2011, and a few fish larvae were occurred in November 2010. Cluster analysis based on the number of individuals of fish larvae showed that 21 month-station sampling units were classified into five groups at the similarity level of 50%, and the results of ANOSIM and SIMPER analysis revealed significant differences in community structure among five groups.

• Korean Journal of Ecology and Environment
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• v.45 no.3
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• pp.314-321
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• 2012

To quantitatively assess the effects of turbidity on egg development and larval fish survival, a laboratory fish rearing experiment was applied to different life stages (newly hatched larval stage, juvenile stage and pre-adult stage) of the Zacco platypus, one of the most universal and tolerant species in Korea. According to the stress index of turbidity in water with exposure time, three different treatments, including a reference condition (1~7 NTU) as well as intermediate (20~150 NTU) and high turbidity conditions (400~1,000 NTU) were applied, and egg hatching and larval fish mortality rates were observed. The mortality rates of newly hatched larval fish were significantly different among treatments (ANOVA, $F_{2,3}$=17.79, p<0.05). Average rates of survival to hatching were 20.9% (${\pm}0.1%$) for reference condition, 11% (${\pm}6.9%$) for intermediate level and 3.2% (${\pm}3.7%$) for high level conditions, respectively. A sudden change of mortality at the high level was observed within 5 days of the experiment. About 84% of juvenile fish survived until 20 experimental periods under conditions of reference turbidity, while survival under conditions of intermediate turbidity was over 80% of larval fish until day 13 of the experiment, but dropped to less than 10% after day 14 and 15 of two experiments. Fish mortality appeared from day 6 of the high turbidity experiment, and 50% mortality was achieved at day 9 to 10 of experiment. Full mortality occurred at day 14 of the experiment (RM-ANOVA, $F_{2,38}$, p<0.005). In the pre-adult stage experiment, no mortality was observed during the experiment at reference level treatment (20 days), while only slight mortality rates were observed for both intermediate and high levels until day 5 of the experiment, however, no further fish died in either experiment. It was significantly different compared to reference condition (RM-ANOVA, $F_{2,20}$=8.28, p<0.01), but no difference was observed between intermediate and high level conditions. Consequently, this tolerant species has been determined to be well adapted to high levels of turbidity in its adult stage, but more vulnerable throughout earlier life stages.

• The Korean Journal of Malacology
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• v.19 no.1
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• pp.19-24
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• 2003

Artificial spawning, larval and spat developments of the bay scallop, Argopecten irradians, which was transplanted from China on 16 August 1996, were investigated monthly until August 1997 in the Deukyang Bay, Jangheung-gun, Jeollanam-do, Korea. Sufficient amount of cultured microalgae supplemented seawater were supplied as food (6 kinds of phytoplankton) for fully grown adult individuals at 17.1-23.2$^{\circ}C$ for 44 days. A total of 45,320,000 eggs were spawned by way of 2 times of artificial spawning inductions such as exposure stimulus to the air and thermal shock (with water temperature) on 29 January and 31 January in 1997. Artificially fertilized eggs were developed to D-shaped larvae (77.5 ${\times}\;63.8\;{\mu}m)$ and metamorphosed to larvae (191.8 ${\times}\;181.2\;{\mu}m)$ 181.2 m) in the attached larval stage on the collectors. A total of 110,000 spats (average 3.04 mm in shell length) were produced at 22.8-26.3$^{\circ}C$ and 31.0-34.4 psu in the indoor rearing tank from 14 February through 7 May in 1997. In case of Argopecten irradians, if the attached larvae in the attachment stage are detached from the collector, they could not live. Accordingly, it is assumed that survival (%) of the attached larvae of A. irridians showed very low because of weak power attached to the collector due to the small number of the byssuses of the attached larva, not the short attachment period by the byssus as seen in other scallops such as Argopecten balloti.

• Journal of Ecology and Environment
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• v.31 no.1
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• pp.45-67
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• 2008

Ocean climate variables ($1900{\sim}2005$), time series of catches ($1910{\sim}2005$) and body size data were used to assess the year-to-year and decadal scale fluctuations in abundance of the fish populations (Japanese sardine, anchovy, jack mackerel, chub mackerel, Pacific saury and common squid) that have spawning grounds in the East China Sea and its adjacent regions. A negative correlation between the abundance of pelagic fishes (e.g. jack mackerel) in the Tsushima Warm Current (TWC) region and the Kuroshio-Oyashio Current (KOC) region was attributed to the climatic modulation of larval transport and recruitment, which depends on the winter monsoon-induced drift, current systems, and spawning season and site. The changes in abundance and alternation of dominant fish populations in the two regions in the 1930s, 1970s, and late 1980s mirrored changes in the climate indices (ALPI, AOI and MOI). Oscillations in the decadal climate shifts between the two regions led to zonal differences in larval transport and recruitment, and hence differences in the abundance of the pelagic fish populations. During deep Aleutian Lows, as in the 1980s, larval transport from the East China Sea to the KOC region increases in association with the strong winter Asian monsoon, cool regime and increased volume transport of the Kuroshio Current systems, whereas during a weak Aleutian Low (as in the 1990s), larval transport to the TWC region increased in association with a weak winter Asian monsoon, a warm regime, and increased volume transport of the Tsushima current system. We postulate that the increased chub mackerel abundance in the TWC region and the decreased abundance in the KOC region in the 1990s are partly attributed to changes in recruitment and availability to the fishing fleets under the warm regime in the spawning and nursery grounds in the East China Sea in association with the quasi-steady state of mild winter monsoon in the 1990s. The fluctuations in chub mackerel and jack mackerel abundance are under the environment-dependant growth form, although the tropicalization was identified in the TWC region. The density-dependant growth form was found in Japanese sardine populations, but no tropicalization by fishing was identified in the long ($10{\sim}15$ year) periods of abundance despite their short ($3{\sim}4$ year) generation time, suggesting that the environment-dependant growth form drove the changes in abundance. Year-to-year and decadal scale variations in abundance and population structure of the Pacific saury responded to climate regime shifts (1976/1977, 1988/1989), suggesting that the fish is a key bio-indicators for changes in the ecosystem.

• Journal of Life Science
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• v.28 no.5
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• pp.563-568
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• 2018

The insect industry is a promising agricultural resource and expected to grow steadily. In Korea, Gryllus bimaculatus and the larvae of Tenebrio molior, Protaetia brevitarsis, and Allomyrina dichotoma were listed as general food ingredients. As interest in these edible insects increases, rearing techniques and nutritious food sources are needed for mass production. In this study, wheat bran, dog feed, and pig feed were investigated for their effects on the larval growth of P. brevitarsis and A. dichotoma. When fermented sawdust with 30% wheat bran was used, the larval survival rate of P. brevitarsis and A. dichotoma (p=0.244341 and p=0.007966, respectively) and growth rate (p=0.001400 and p=0.000051, respectively) were significantly lower than those of the control (fermented sawdust with no supplement). Therefore, fermented sawdust with a high density of wheat bran was inappropriate for both insects. When fed fermented sawdust with 2.5 or 5% of dog and pig feed, the survival rate and growth rate of the larvae were higher than those of the control. Interestingly, the maximum larval weight with 2.5% dog feed was increased by $3.35{\pm}0.10g$ and $32.59{\pm}0.79g$ for P. brevitarsis and A. dichotoma, respectively. In addition, the larval period of both was shorter than that of the control by 40 days or more. Therefore, it is considered that animal feed can be used as a feed source for these edible insects.

• Animal cells and systems
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• v.5 no.1
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• pp.59-64
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• 2001

To understand the late gut development and differentiation, identification and characterization of target genes of homeotic genes involved in gut development are required. We have previously reported that homeodomain proteins can regulate expression of the cell proliferation-related genes. We investigated here the expression of the Drosophila proliferating cell nuclear antigen(PCNA) and E2F(dE2F) genes in larval and adult guts using transgenic flies bearing lacz reporter genes. Both PCNA and dE2F genes were expressed strongly in whole regions of the larval and adult guts including the esophagus, proventriculus, midgut and hindgut, showing higher expression in foregut and hindgut imaginal rings of larva. Nitric Oxide(NO) has been known to be involved in cell proliferation and tumor growth and also to have an antiproliferative activity. Therefore, we also investigated effects of NO on the expression of PCNA and dE2F genes in gut through analyses of lacz reporter expression level in the SNP (NO donor)-treated larval guts. Expressions of both PCNA and dE2F were greatly declined by SNP. The inhibitory effect of NO was shown in whole regions of the gut, especially in hindgut, while the internal region of proventriculus, esophagus, foregut imaginal ring and hindgut imaginal ring was resistant. Our results suggest that this inhibitory effect may be related with the antiproliferative activity of NO.