• Animal cells and systems
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• v.13 no.3
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• pp.339-344
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• 2009

This study aims to find out the effect of heavy metals, as is the case of EDCs (endocrine disrupting chemicals), on reproductive endocrine disruption of aquatic animals. In the present experiment zinc, which is a heavy metal well known for its androgenous activity, was used. The experimental period was 24 weeks, starting in November during the inactive stage of the clam's reproductive cycle. The experimental groups were composed of one control condition and three zinc exposure conditions (0.64, 1.07, and 1.79 mg/L). The sex ratio (F:M) was 1:1.06 in the control group and 1:1.70 in all the exposed group, illustrating the tendency for higher proportion of males with increases in zinc concentration. Gonad maturity was higher in 1.07, and 1.79 mg/L groups compared to the control group, with higher maturity observed in males than females. Intersex individuals made up 24.7% of the exposed group, while females exhibited a higher ratio than the males with increasing zinc concentration. The results of this study indicate that zinc functions as an androgenic effector on the reproduction of Gomphina veneriformis.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.6
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• pp.581-585
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• 1985

This study was carried out with blue mussels at Otsuchi Bay in Japan from August 1981 to May 1982, in order to investigate the effect of the parasitic pea crab (Pinnotheres pholadis) on the reproductive capacity of host blue mussels (Mytilus edulis galloprovincialis). The results show that pea crabs delay gonad development of host mussels about one month and lower their fatness rate by intercepting nutrients. The parasitization with pea crabs is thought not to prevent spawning activity itself, but to reduce the number of germ cell resulting in the reduced space of gonads.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.5
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• pp.496-510
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• 2019

We investigated the reproductive characteristics of the sweetfish Plecoglossus altivelis, including changes in the gonadosomatic index (GSI), frequency of gonad developmental stages, and abundance of drifting larvae, in three streams (Gangjeong, Yeonoi, and Ongpo) on Jeju Island from May 2004 to December 2005. The GSI values of female P. altivelis in all Jeju streams began to increase in September and reached a maximum in October and November. Peak GSI values in males occurred in Gangjeong from October to November, in Yeonoi from November to January, and in Ongpo from September to October. The gonadal development of P. altivelis was classified into four stages: growth (March to October), maturity (September to December in females; July to December in males), spawning (September to January), and degeneration (October to March in females; after November in males). Drifting larvae were collected from October to January. These results suggest that the main spawning activity of P. altivelis in Jeju streams occurs from October to November. The information about the reproductive characteristics of P. altivelis obtained in this study is critical to fishery management for this species.

• Ocean and Polar Research
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• v.36 no.2
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• pp.121-134
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• 2014

Sessile marine bivalves including mussels, oysters and clams are often used as a sentinel species in coastal environmental monitoring since changes in the environmental quality are often well preserved in their tissues and shells. In this study, we investigated overall health condition of the Mediterranean Mussel, Mytilus galloprovincialis on the south coast using histology. Reproductive condition as gonad index (GI), condition index (CI) as a ratio of the tissue weight to the shell weight, digestive gland atrophy (DGA), types of parasites, and pathologic conditions including erosion, necrosis, hemocyte infiltration, and neoplasia were examined from each histological preparation. GI decreased from March to July then increased from July to September and spawning mussel could be observed as early as in April and the activity continued until September. CI also followed the monthly changes in GI, indicating that decrease in CI was associated with the weight loss due to spawning. DGA increased from March to June, decreased in July and increased from July to September. High DGA values observed in June and September were coincided with spawning and high water temperature. Histology also showed high prevalence of erosion in the digestive gland in June (36.0%) and September (56.4%), suggesting that high water temperature and spawning acted as environmental stressors. No parasitic organism was identified during the survey, although some symbiotic copepods were observed. Histology was found to be useful and affordable technique in monitoring the overall health of mussel, providing useful pathologic information of the cells and tissues.

• Animal cells and systems
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• v.16 no.4
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• pp.329-336
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• 2012

This study evaluated ecological health, using various biomarkers and bioindicators, of pale chub (Zacco platypus) as a sentinel species, in Daejeon Stream, South Korea, during AprilMay 2011. The biomarkers and bioindicators were compared among three sites of control: Reference ($C_z$), transition ($T_z$), and the urban zones ($U_z$); and the 7-Ethoxyresorufin-O-deethylase (EROD) activity, DNA damage, acetylcholinesterase (AChE) activity, and vitellogenin (VTG) concentrations were more significantly increased in the $U_z$ than in the $C_z$. Also, physiological markers such as condition factor, liver somatic index, visceral somatic index, and gonad somatic index were significantly increased in the $U_z$ than in the $C_z$. For the health assessments, three categorized parameters of blood chemistry, molecular biomarkers, and physiological bioindicators were standardized and calculated as a star-plot, representing values of Integrated Health Response (IHR). Values of IHR had more significant (P<0.05) increases in the $U_z$ than any other zones, indicating an impairment of ecological health by organic matter, nutrients (N, P), and toxic chemicals. This study is based on low levels of biological organization approach of molecular and physiological biomarkers and bioindicators, so further study of high-levels of biological organization approach such as community and population is required for overall range of health assessments. The approach of IHR values, however, may be useful in providing early warning of future impacts on ecological health.

• Development and Reproduction
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• v.11 no.3
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• pp.219-226
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• 2007

This study was conducted to identify optimistic primordial germ cells'(PGCs) migration activity using heat activated busulfan treatment for the increasing germline chimerism. Donar PGCs viability tests of important conditions for useful germ line chimerism indicated approximately $70{\sim}80%$ viability was time dependent. Transplantation experiments of PGCs into recipient embryos after busulfun treatment, showed the treatment group having 23.5% viability. By comparison, the control group showed 4.8% viability. The 96 hour treatment group and the 118 hour treatment group of the cultured PGCs showed high migration activity. Generally, the transplantation method would consider morphological and physiological characteristics before transplantation. In the present study, the effect of busulfan on migration activity showed viability highest at 53.4% after 48-hour incubation time. However, a previous study showed the best condition for transplantation time to be prior to the 48-hour incubation period, when the chicken embryo does not yet have a developed blood vessel system. In conclusion, an important condition for the production of a transgenic chicken is that most donor PGCs migrate into the recipient embryo without any inhibitory factors. The present results suggest, perhaps by using this modified method of transplantation, it can produce a more efficient chimeric germ line, transgenic chicken.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.24 no.5
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• pp.327-339
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• 1991

The present paper is a histological study of neurosecretory cells in the brain and the thoracic ganglion with the gonadal development in Palaemon serrifer. The reproductive cycle includes the successive stages of the growing period (February-March), the mature period(April-May), the ripe and spent periods(June-August) and the degenerative and resting periods(September-January). The neurosecretory cells are grouped into four types based on Matsumoto(1958) : A-,A'-, B- and E-cells. A- and A'-cells are $80-90{\mu}m,\;B-cell\;is\;30-40{\mu}m$ and E-cell is $10-15{\mu}m$. A- and B-cells are the positive to CHP and AF, while B-cell is the positive only to AF. The secretory grannules of a A-cell are transported to the axon, and at the same time they are discharged through the peripheral membrane. Of the four neurosecretory cells, A- and I-cells show the difference of secretory activity according to the gonad developmental process. In the female, A-cells show secretory activity for the ripe and spent periods, while I-cells show for the mature, ripe and spent periods. In the male, A-cells show secretory activity for the mature, ripe and spent periods, while I-cells show for the growing, mature, ripe and spent periods.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.1
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• pp.37-43
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• 2012

We have investigated the effect of melatonin (MLT) on specific growth rate (SGR% $day^{-1}$), condition factor (k), gonado-somatic-index (GSI), histological structures of gonads, serum as well as gonadal protein and lipid in Nile tilapia Oreochromis niloticus. MLT treatment in the dose of 25 ${\mu}g/L$ for three weeks reduced SGR% $day^{-1}$ ($0.9{\pm}0.04$) as compared to control ($1.23{\pm}0.026$). The GSI value was significantly (p<0.05) reduced to $1.77{\pm}0.253$ from control where it was $2.56{\pm}0.25$. Serum protein level increased from $9.33{\pm}2.90$ mg/ml (control) to $11.67{\pm}1.45$ mg/ml after MLT treatment while there was depressed serum triglycerides ($86.16{\pm}1.078$ mg/dl) and cholesterol ($126.66{\pm}0.88$ mg/dl) as compared to control values where these were $123.0{\pm}1.23$ mg/dl and $132.0{\pm}1.65$ mg/dl respectively. Histological structure of ovary showed small eggs of early perinucleolus stage after MLT treatment while testicular structure of control and MLT treated fish was more or less similar. It is concluded that exogenous melatonin suppressed SGR% $day^{-1}$, GSI, ovarian cellular activity, protein and lipid biosynthesis, in tilapia suggesting that melatonin is useful in manipulating the gonadal maturity in fishes.

• Korean Journal of Ichthyology
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• v.12 no.1
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• pp.46-53
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• 2000

Artificial gonadal maturation and spawning inducement of striped knife-jaw Oplegnathus fasciatus were studied. Effects of water temperature and photoperiod under different regims on gonadal activity and maturation of three years old O. fasciatus were investigated histologically. In experiment I (Exp. I), water temperature was gradually increased from $14.5^{\circ}C$ to $21.0^{\circ}C$ and photoperiod was also gradually increased from 10 : 30 L to 15 : 30 L from December 1996 to February 1997 and this conditions were maintained till April. In experiment II (Exp. II), water temperature was increased in the same way from Exp. I and photoperiod was controlled as natural condition till early March and then increased to 15 : 30 L immediately. Control fish were reared in net-cage culture system in the sea from December 1996 to April 1997. Gonadal activity was initiated by increasing water temperature in both Exp. I and II from January. In Exp. I, gonadal maturation and spawning were induced from February when water temperature and photoperiod reached at $21.0^{\circ}C$ and 15 : 30 L, respectively. In Exp. II, complete gonadal maturation was not induced until early March but after treated by compensatory long photoperiod (15 : 30 L), the gonad was matured and subsequently spawning occurred.

• Journal of Life Science
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• v.28 no.3
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• pp.284-292
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• 2018

The melanin-concentrating hormone (MCH), a cyclic hypothalamic peptide composed of 17 amino acids, was initially identified in chum salmon (Oncorhynchus keta) as a regulator of pigmentation. Mammalian MCHs are cyclic hypothalamic peptides composed of 19 amino acids that regulate food intake and energy homeostasis. The present study examined not only MCH expression of different tissues but also the melanohore aggregation and intracellular $Ca^{2+}$ influx of fMCH and the other MCH. Real-time qPCR showed that MCH expressed specially in the brain, gonad, and ovary, and expression of MCH was observed during the developmental stages. In the application of synthetic fMCH and both types of synthetic fMCH, dN-fMCH and dC-fMCH, scale melanophore induced significant changes in aggregation activity with various concentrations of MCH. Also, compared to hMCH and sMCH, fMCH exhibited a 36~99.85% increase in relative potency (%), whereas aggregation of dN-fMCH and dC-fMCH remained in a high concentration. However, dispersion was induced rapidly according to be low concentration of dN-fMCH and dC-fMCH. We show that fMCH and its derivates were bound human MCHR1 and rat MCHR expressed in HEK293T cells with nano-molar affinity and are likely to be ligand-induced to mobilize intracellular $Ca^{2+}$. These results may provide new ligands for binding assay with MCHew ligands, as a structure similar to the mammalian MCH structure was discovered in fish. Once the fMCH receptor system is in place, it can be compared to the MCH system of mammals in terms of MCH function.