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        검색결과 5

        1.
        2013.04 구독 인증기관·개인회원 무료
        In the Northern Hemisphere, northward shifts due to global warming are apparent in various organisms such as butterflies, birds, and plants. In South Korea, ranges of butterflies are expected to shift northwards. We tested whether distribution limits of Korean butterflies shift northwards. We used two Korean butterfly atlases (1938-1950, 1977-2011) for analysis of the range shifts. Northern limits of southern species moved significantly northward (ca. 60 km) for 50 years, whereas southern limits of northern species did not significantly move northwards nor southwards. This finding parallels with other studies on butterflies and birds in Europe and North America.
        2.
        2011.10 구독 인증기관·개인회원 무료
        It is expected that the successful nationwide reforestation and the increased temperature would greatly change butterfly fauna in South Korea. We compared current data (2002~2007) regarding abundance and presence of butterfly species at two sites in the central portion of the Korean Peninsula to data from late 1950s and early 1970s for the same sites. The expected changes were documented by abundance change of butterflies at two study sites in the previous study. Using the same data, the greatly changed species and the change of species presence were analyzed. Population changes of 99 butterfly species which occurred at both sites were significantly correlated between two sites. The greatly increased species included three Southern (S) species and one Northern (N) species. However, the greatly declined species included five N species and no S species. This change is coincided with the expectation from the northward movements of butterfly species due to global warming. The current status of the greatly changed species was discussed on the review with other studies. The binary data(presence/absence) in present study support the expected changes of butterfly species based on global warming and reforestation. The interactive effect of two environmental changes was also recognized as like the change of abundance in the previous study.
        3.
        2009.10 구독 인증기관·개인회원 무료
        Ant species were reported to have specific vertical distribution in high mountains in Korea. The vertical distribution was recognized in Hanla mountain being highest in South Korea using pitfall traps in 2006. This phenomena suggests that temperature may be a main factor for distribution of ant species, since 0.5~0.6℃ of temperature decrease per each 100 m of altitude. The present study was carried out to test this hypothesis. Ant communities were surveyed using pitfall traps (ten traps per each site) at 234 sites, which included 9 high mountains in South Korea. The vertical distribution of ant species were found in all the high mountains. Abundance data (probability of occurrence, %) of seventeen abundant ant species which occurred at more than 10% of the study sites were analyzed using multiples regression analysis with four independent factors such as temperature, precipitation, light intensity, and NDVI. As results of the regression analysis, temperature was most important in determining the abundance in 11 of 17 species. Light intensity was most important in 3 species, and precipitation in 1 species. In the 11 species being highly dependent on temperature, determination index (R2) of regression model with one factor of temperature was approximately 90% of determination index of the regression model with all four factors. On the base of dependence on temperature and of ecological characteristics (ground foraging), six species such as Paratrechina flavipes, Myrmica kotokui, Pachycondyla javana, Pristomyrmex pungens, Camponotus atrox, and Crematogaster osakensis were selected as bioindicator for global warming. In the bioindicator ant species, M. kotokui and C. atrox were predicted to decline in abundance and distribution in Korean peninsula as temperature increases, whereas other four species including P. flavipes, P. javana, P. pungens, C. osakensis were predicted to increase. Temperature-Distribution models were established in four most temperature-responsive species including P. flavipes, P. javana, P. pungens, and M. kotokui, and distribution maps of the species were made from the model. Reversely, temperature was estimated from ant data of five bioindicator species using regression model, of which R2 is 0.66.
        5.
        2003.09 서비스 종료(열람 제한)
        Tributyltin chloride (TBTCI) is an organotin compounds that have been widely used as antifouling agents and bioaccumulated in the food chain. TBTCI has been known to induce imposex in female gastropods. There are several reports that TBTCI increased testosterone level and inhibited the conversion of testosterone to estradiol by the aromatase cytochrome P450 enzyme. In this studies, we investigated the effects of TBTCI on steroidogenesis in testes, We dosed to 4-week-old Spragus-Dawleys (SD) male rats with TSTCI (0, 1, 5, 10, and 20mg/kg/day) daily by gavage for 14 days. TBTCI significantly decreased the weights of seminal vesicle, prostate, cowper's gland and LABC at 10 and 20mg/kg/day but significantly Increased the weights of liver at 10 and 20mg/kg/day and adrenals at 20mg/kg/day. mRNA levels of steroidogenic acute regulatory (StAR) and P450 aromatase were decreased and mRNA levels of cytochrome P450 17-hydroxylase/ lyase (P450c17) were increased by TBTCI. TBTCI significantly increased serum testosterone level in dose-dependent manner. From above results, we found that TBTCI altered mRNA levels of enzymes related steroidogenesis, weights of organs and serum testosterone levels. This suggests that change of hormone levels may be due to alteration of mRNA levels of steroidogenic enzyme in testes, but further studies are necessary to investigate hormone levels in testis organ in order to find a relation of enzyme related to steroidogenesis with hormone levels. This work was supported by the Korea FDA Grant KFDA-03131-EDS-010.