• Korean Journal of Ichthyology
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• v.23 no.3
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• pp.234-241
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• 2011

Habitat, reproduction and feeding habit of endangered fish Koreocobitis naktongensis from Jaho stream, Gyeongsangbuk-do, Korea were investigated from March 2010 to June 2011. This species inhabits at the upper and middle parts of stream, which were composed of cobbles and pebbles bottom. The current velocities in these microhabitat were 5~10 cm/sec and depth were 50~110cm. The sex ratio of female to male was 1 : 0.92. It is presumed that the spawning season is from May to June when water temperatures were 17 ~ 20$^{\circ}C$. The average number of mature eggs in ovary were about 22,643 (15,909~30,323), mean egg diameter was 0.87${\pm}$0.05mm. K. naktongensis fed mainly on Chironomidae (IRI, 72.0%) and Ephydridae (26.9%) of Diptera.

• Journal of Animal Reproduction and Biotechnology
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• v.34 no.4
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• pp.311-317
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• 2019

Reproductive potential decreases with age. A decrease in male fertility is due to a combination of morphological and molecular alterations in the testes. Transient receptor potential vanilloid receptor-1 (TRPV1) is associated with aging and lifespan, and its activation causes apoptotic cell death in various cell types. However, the effect of TRPV1 on testicular apoptosis in aged mice has not yet been reported. TRPV1 knockout (KO) mice had a longer lifespan than that of wild-type (WT) mice. Lifespan was increased by 11.8% in male TRPV1 KO mice compared to that in WT mice. TRPV1 KO males lived approximately 100 days longer than WT males on average, and the maximum lifespan was markedly extended in TRPV1 KO mice compared with that in WT mice. The TRPV1 expression levels were highly increased in the testes of older mice. TRPV1 was expressed in the entire testes region of the old mice. In addition, old TRPV1 KO mice had lower testicular apoptosis than that of WT mice. Our results show that TRPV1 induces testicular apoptosis and suggest that TRPV1 may be associated with testicular aging.

• Korean Journal of Animal Reproduction
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• v.15 no.3
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• pp.179-187
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• 1991

This experiment was carried out to develop a new technique of identifying XX of XY-bearing bisected embryos prior to implantation by immunological method. H-Y antiserum prepared in inbred Wastar female rats by repeated immunization with spleen cells from males of the same strain. The reactivity of H-Y antibody was confirmed by culturing mouse embryos in the medium containing H-Y antiserum and complement obtained from the guinea pig. The optimal condition for the activity of H-Y antibody was also investigated by culturing embryos under the concentraton or affected H-Y antibody was also investigated by culturing embryos under the concentration or affected H-Y antibody and culture rate. However, production of live young or sex rates of male and female from embryos transferred with psudopregnant. The biological test with the morula stage embryos showed that H-Y antibody was formed in all female rats immunized with spleen cell, but it was formed only in 80% female rats immunized with the antigen. When the bisected mouse embryos were cultured in vitro for 5~6 hours in morula stage, of 457 bisected embryos 81.4% of then were developed to the blastocyst stage. When the concentration rate of complement to H-Y antiserum varied from 1.0~5.0${mu}ell$, the lysis-rate of embryo was 19.5 to 67.3%. The concentration rate of complement did not influence the lysis-rate of embryos(P<0.05). The morphology embryos of bisected, zona-free and intact embryos showed the embryos lysis rate of 58.6, 42.7 and 48.5% respectively(P<0.05). Pregnancy rate were 50.0, 45.5 and 57.1% in psudopregnant recipient transferred with bisected, zona-free and intact blastocyst embryos. However, production of live youngs, sexual rate of male or female was 24(50.0:50.0), 22(45.5:55.5) and 36(58.3:41.7)mice, but affected and non affected half embryos with H-Y antiserum treatment was 23.1 and 26.7%. Also production of live youngs and sexual rate was 14(92.9:7.1) and 17(17.6:82.4)mice in affected and non affected half embryos in H-Y antiserum treatment(P<0.05).

• Korean Journal of Animal Reproduction
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• v.26 no.4
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• pp.353-360
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• 2002

Although successful pronuclear formation and apposition were seen in porcine oocytes following mouse sperm injection, little is known on the morphology of male and female pronuclei following sperm injection. The objective of this study is to describe the ultrastructure of porcine zygote following murine sperm injection in relation to the chronology of pronuclear S phase. At 40h ~ 44h following in vitro maturation, Cumulus cells were removed in TCM-HEPES with 0.1% hyaluronidase. Then, spermatozoa was injected into the cytoplasm of oocytes. After. injection, all oocytes were transferred to NCSU23 medium and cultured at 39$^{\circ}C$ under 5% $CO_2$ in air. Oocytes were fixed in 2% glutaraldehyde in Dulbeccos phosphate-buffered saline and observed by Transmission Electron Microscopy. Nuclear precursor bodies were observed in each pronucleus. A cluster of large and small granules was attached in the nucleolus precursor body. After the apposition of male and female chromatin, chromatin condensation was observed throughout the nucleoplasm and nucleolus precursor bodies and condensed chromatin in contact with clusters of small and large granules and the nuclear envelope were found in apposed pronuclear regions. These results suggest that non-species specific nuclear cytoplasmic interactions take place during pronuclear formation and apposition following sperm injection.

• Clinical and Experimental Reproductive Medicine
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• v.40 no.4
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• pp.155-162
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• 2013

Objective: Stress is known to be an inhibitor of the reproductive hypothalamic-pituitary-gonadal (HPG) axis. However, the neural and molecular connections between stress and reproduction are not yet understood. It is well established that in both humans and rodents, kisspeptin (encoded by the kiss1 gene) is a strong stimulator of the HPG axis. In the present study we hypothesized that endocannabinoids, an important neuromodulatory system in the brain, can act on the HPG axis at the level of kiss1 expression to inhibit reproductive function under stress. Methods: Adult male Wistar rats were unilaterally implanted with an intracerebroventricular cannula. Afterwards, the animals were exposed to immobilization stress, with or without the presence of the cannabinoid CB1 receptor antagonist AM251 (1 ${\mu}g/rat$). Blood samples were collected through a retro-orbital plexus puncture before and after stress. Five hours after the stress, brain tissue was collected for reverse transcriptase-quantitative polymerase chain reaction measurements of kiss1 mRNA. Results: Immobilization stress (1 hour) resulted in a decrease in the serum luteinizing hormone concentration. Additionally, kiss1 gene expression was decreased in key hypothalamic nuclei that regulate gonadotrophin secretion, the medial preoptic area (mPOA), and to some extent the arcuate nucleus (ARC). A single central administration of AM251 was effective in blocking these inhibitory responses. Conclusion: These findings suggest that endocannabinoids mediate, at least in part, immobilization stress-induced inhibition of the reproductive system. Our data suggest that the connection between immobilization stress and the HPG axis is kiss1 expression in the mPOA rather than the ARC.

• Journal of Animal Reproduction and Biotechnology
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• v.35 no.1
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• pp.73-85
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• 2020

A high-cholesterol diet can reduce male fertility. However, it is not known whether a high-cholesterol diet can regulate the expression of genes involved in sperm maturation and sperm fertilizing ability. Quercetin, a natural product, is known to have cytoprotective effects by regulating lipid metabolism in various cell types. This study aimed to confirm the expression of genes involved in sperm maturation in the testes of mice fed a high-cholesterol diet and to determine whether quercetin can reverse the genetic regulation of cholesterol. Mice were divided into groups fed a normal chow diet and a high-cholesterol diet. Mice fed the high-cholesterol diet were dose-dependently supplemented with quercetin for 6 weeks. Investigations using quantitative PCR and in situ hybridization revealed that the high-cholesterol diet alters the expression of genes associated with sperm maturation in the testes of mice, and this was reversed with the supplementation of quercetin. In addition, the high-cholesterol diet regulated the expression of genes related to lipid metabolism in the liver of mice. Under a high-cholesterol diet, quercetin can improve male fertility by regulating the expression of genes involved in sperm maturation.

• Korean Journal of Agricultural Science
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• v.47 no.4
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• pp.867-884
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• 2020

Trypoxylus dichotomus is highly utilized in the domestic insect industry and bred at many farms nationwide. Recently, the number of farmers has been increasing due to the expansion of its use in food and medicine. However, the traditional breeding methods have high economic costs, which include relatively large breeding boxes, large amounts of sawdust and a 2 to 1 ratio (or higher) of female to male. Thus, it is essential to develop a cost-effective breeding method. In this study, a breeding cage with a partition was designed and used to investigate the reproduction rate of T. dichotomus with only a single pair of male and female insect. According to the investigation, the average number of eggs laid in the un-partitioned breeding cage was 93.6, and 121.3 eggs were laid in the partitioned breeding cage. This result shows that T. dichotomus lays more eggs in the partitioned breeding cage rather than in the un-partitioned breeding cage. In addition, it was found that T. dichotomus tends to lay more eggs in compressed sawdust, which was harder than the common fermented sawdust. Through a wind-tunnel assay, it was shown that the ovipositing female recognizes the eggs and avoids them to disperse their eggs elsewhere. These results indicate that the partitioned breeding cage may increase the hardness of the sawdust, restrict the adult's movement and provide a new place for oviposition for the female, and therefore results in an increased reproduction rate with less cost.

• Development and Reproduction
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• v.1 no.2
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• pp.181-187
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• 1997

This study has been conducted to investigate the mating behavior, time sequence of mating and time limit with which female can fulfill spawning and brooding after pre-spawning molting in the giant fresh-water prawn, macrobrachium rosenbergii reared in the laboratory. the results obtained were summarized as follows. Mating happened spontaneously as the following sequences: courting gesture, seizure of female by male, mounting, turning of female, copulation. The entire mating lated approximately seven minutes. The endopodite of 2nd pleopod of male bore the appendix masculins whcih are male's secondary sex characteristic. cinciulli was formed at the distal portion of appendix interna which are on the upper portion of appendix masculins and helped stabilizing the connection of each side of 2nd pleopod during mating. After the connection of each side of 2nd plepod was fixed on the posterior portion of the thoracic sternum in female, a gelatinous spermatophore that emitted at the basipodite of 5th pereiopod during courting gesture was deposited on the ventral groove of 2nd, 3rd, 4th and 5th pereiopod. time limit which female can fulfill copulation and brooding was from 3 hours to 15 hours after pre-spawning molting.

• Journal of Forest and Environmental Science
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• v.32 no.2
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• pp.113-119
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• 2016

The long lived iteroparous conifers produce male and female gametophyte for hundreds of years once they reach the reproductive stage, however, the production of seed is not frequent. This phenomenon of infrequent seed production in conifers is yet to be understood. An attempt to study this change in cone production in Cedrus deodara of Western Himalayas -a species reported to be mainly monoecious and rarely dioecious has been made. The observations recorded on selected trees of flowering/fruiting stage for four years at four different locations have shown the species to be dioecious with higher percentage of female trees during good seed year but with no definite or predictable pattern of reproduction in the trees. A decline in production of female trees was witnessed at all but one location immediately year after reaching the maximum (good seed year). The phenomenon of seed production has been observed to be cyclic and site specific. A change in the sexual behavior of the trees from male to female or vice-versa, male or female turning monoecious or vegetative and vegetative coming to reproductive was unpredictable.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.1
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• pp.27-34
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• 2006

Sexual maturation and reproductive cycle of the bat star Asterina pectinifera were investigated by histological method. Specimens were collected monthly in Donghwari, Gosunggun, Korea from January 2004 to February 2005. The bat star was dioecious. The gonads are composed of a number of gametogenic follicles. The gonadosomatic index (GSI) of female and male were reached the maximum in July (5.72, 4.54) and the minimum in December (0.89) and January, February (0.51), and the gonad index (GI) of female and male were reached the maximum in July (3.53, 3.91) and the minimum in August (0.95) and October to December (1.0), respectively. The main spawning was from August to September. The reproductive cycle of the bat star could be divided into five stages: in the female, inactive (November-February), early active (January February), late active (March-June), ripe (July), spent and degenerative (August-November) and in the male, inactive (November-February), early active (January-March), late active (April-June), ripe (July), spent and degenerative (August-October), respectively.