• The Korean Journal of Zoology
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• v.31 no.2
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• pp.87-94
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• 1988

Korean frogs (R. dybowskii and R. nigromaculara) were collected from chonnam area and their oocyte maturation was induced by using in ultro follicle culture system. Follicles were isolated from the frog ovary and cultured for 24 hr in (amphibian Ringer's soluion AR) at 22 C in the presence or absence of hormones. Follicular cocytes of R. dybowskii were induced to mature (germinal vesicle breakdown, GVBD) by the presence of progesterone, 0.1 $\mu$g/2 ml and that of R. nigromaculata by 1 $\mu$g/2 ml of progesterone. Follicles of the frogs were also responded to (frog pituitary homogenate FPH) in terms of their cocyte maturation. Follicular cocytes of R. dybowskii were induced to mature by FPH at concentration of 0.01 pituitary equivalent/2 ml and that of R.nigromaculata at 0.1 pit equiv./2 ml. The culture time required for the maturation of bath frog follicles was 915 hr. The responsiveness of the follicles of korean frogs to hormones (progesterone or FPH) was nearly the same as that of R. pipiens which are most commonly used amphibians. Particularly, follicular cocytes of R. dybowskii used from February matured spontaneously without stimulation of hormones during in vitro culture. Furthermore, those cocytes were spontaneous- ly ovulted when the ovarian fragments were cultured in a flask.

• The Korean Journal of Zoology
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• v.31 no.3
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• pp.177-184
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• 1988

The pattern of progesterone production and secretion of frog(R. dybowskii) follicles was investigated in follicle culture in vitro. Involvement of cAMP in the regulation of the steroid production by the follicles was also investigated by manipulating endogeneous cAMP level with forskolin and/or 3-isoburyl- 1 - methylxanthine(IBMX). Endogeneous follicular progesterone level increased rapidly in one hour of culture by treatment of frog pituitary homogenate(FPH) and reached peak level at 2 hours or later. But the absolute amount of progesterone produced (60-300 pg/follicle) or the peak time of the honnone level was different between individual animals. Basal level of progesterone in untreated sister follicles was very low (around 10 pg/follicle) and nearly undetectable in most cases regardless of culture lime. Secretion level of progesterone by the follicles obtained by measunng the honnone in the culture media was just the reflection of the intrafollicular level. Exogeneously added forskolin, an adenylate cyclase stimulator, and/or IBMX, a phosphodiesterase inhibitor, could mimic FPH action in terms of progesterone production and secretion. Thus, it seems clear that FPH regulates progesterone production via cAMP system in the follicle cells.

• The Korean Journal of Pharmacology
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• v.22 no.2
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• pp.105-114
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• 1986

This study was undertaken to search for a new antiarrhythmic agent in natural plants. Extracts of Buxus microphylla var. koreana Nakai have been used as folk remedies of several diseases, including malaria and venereal disease, but any study on the pharmacological actions of this plant has not yet been carried out and its active ingredients have not been identified. In our laboratory, we isolated buxuletin (nonalkaloid) and cyclobuxine D (steroidal alkaloid) from Buxus microphylla var. koreana Nakai and reported their pharmacological actions: diuretic effects of buxuletin in rabbits and hypotensive effect of cyclobuxine D in rats. In the present study, we investigated the effect of cyclobuxine D on isolated frog heart and heart rate in urethane anesthetized rats. In order to clarify the mechanism of bradycardic effect of cyclobuxine D, we examined the changes of the ECG parameters (PR, QRS and R ${\alpha}$ T interval) produced by intravenous injection of cyclobuxine D in anesthetized rats. Cyclobuxine D depressed the contractile force in isolated frog heart and exerted a dose-dependent bradycardic effect in anesthetized rats. Intracerebroventricular injection of cyclobuxine D caused a fall in blood pressure and an increase in heart rate, but those effects were not significant. Cyclobuxine D prolonged the PR interval and RaT interval (${\alpha}$ Tindicates the apex of T), but was without significant effects on the duration of the QRS complex and PRc in urethane anesthetized rats.

• Korean Journal of Ecology and Environment
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• v.54 no.4
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• pp.363-373
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• 2021

An ecological niche is defined as the specific role of a species influenced by time, space, and other resources. By investigating overlaps between ecological niches of different species, we could estimate the degrees of interspecific competition. Such studies often use geographic information systems (GIS) to discover niche overlaps between species. In this study, we used GIS to estimate the spatial niches of two Korean frog species(Pelophylax nigromaculatus and P. chosenicus). This enabled us to predict their geographic distributions in order to identify their coexistence regions and distribution patterns. The results confirmed that altitude was an important variable for predicting their distribution, with a correlation with their climatic range. Spatial distributions of the two frog species were highly overlapped, as the distribution range for P. nigromaculatus included most of the range of P. chosenicus, showing a sympatric distribution pattern. Within the coexisting regions, however, the presence sites for the two species did not overlap, implying weak competition. To confirm the principal factors influencing their competitive relationship and reasons for their sympatric distribution pattern, we need more detailed in-depth studies on the diverse environmental variables within the regions where the two species coexist. By doing so, we would be able to identify various mechanisms for avoiding competition in sympatric frog species.

• Journal of Life Science
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• v.34 no.4
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• pp.264-270
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• 2024

This study is conducted to analyze environmental factors that affect the ecology of boreal digging frog and use them as basic data for selecting (or creating) suitability of alternative habitats for survival and monitoring method from 2020 to 2022 after boreal digging frog were relocated to the alternative habitats in 2019. Analyzing the environment of the alternative habitats showed that the criteria suited the followings: distance from wetlands, grasslands and rivers was within 5 m, the low-rise grassland was 6,000 m², soft soil was at a depth of ≥20 cm, and the area of permanent wetlands was 5,000 m² wide. As a result of the correlation analysis between meteorological factors and population (n) and breeding, there was a significant correlation between rainfalls and breeding (p<0.01). During the monitoring, it was confirmed that the SVL (Snout-Vent Length) and BM (Body Mass) of the translocated population were maintained (p>0.05), and it was found that the proximity of the habitat and spawning pond, securing food space (grasslands), soil quality, and wetlands could function as an alternative habitat if conditions were met. As a result of analyzing the meteorological factors affecting the population of boreal digging frog, the SVL had a statistical impact on the minimum temperature, maximum temperature, relative humidity, and the rainfall (p<0.05). In the case of breeding, rainfall was found to be affected (p<0.01), and the population was statistically affected by the average temperature, minimum temperature, and relative humidity (p<0.05).

• Proceedings of the Zoological Society Korea Conference
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• 1998.10b
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• pp.156.1-156
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• 1998

No Abstract, See Full Text

• Proceedings of the Zoological Society Korea Conference
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• 2000.04a
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• pp.68.2-68
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• 2000

No Abstract, See Full Text

• Proceedings of the Zoological Society Korea Conference
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• 2001.10a
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• pp.190.2-190
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• 2001

No Abstract, See Full Text

• The Optical Journal
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• s.160
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• pp.17-19
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• 2015

최근 글로벌 디자인 업체인 Frog의 Cobie Everdell 크리에이티브 디렉터는 글로벌 차량 제조사들이 차량의 대시보드 UI 디자인을 재고할 필요가 있다고 주장했는데, 자율 주행 자동차(또는 무인 자동차) 도입 확대에 맞춰 차량 내 대시보드 역시 대형 스크린으로 전환되면서 음성이나 동작으로 제어가 가능한 형태로 진화할 것으로 전망

• Proceedings of the Zoological Society Korea Conference
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• 1996.10a
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• pp.249.1-249
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• 1996

No Abstract, See Full Text