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        검색결과 1,279

        622.
        2011.10 구독 인증기관·개인회원 무료
        Artificial insemination and embryo transfer is one of the most important factors affecting to the production of fawn from deer nuclear transfer in the field of deer farms. This study* was conducted to establish the production technology of nuclear transfered embryo in deer. For estrus synchronization or superovulation tretments in flower deer and elk, each 10 does were inserted into the vagina for 14 days with CIDR (Pfizer New Zealand Ltd., NZ) for elk and Ring-CIDR (Bioculture Co., Ltd., Korea) for flower deer, and then those inserted devices were removed. The estrus synchronization of each 6 does were induced by the intramuscular injection of PGF2α (25 mg/head) and PG600 (hCG 200IU + PMSG 400IU, Intevet, Holland). Then, the superovulation of each 4 does of flower deer and elk was induced by additional injection of FSH (200 mg/ head) twice with an interval of 24 hours , respectively. Follicular oocytes were collected from each 2 does superovulated after 48 hours since the injection of PG600 and FSH. In the meantime, the ovarian response and the number of the collected ovarian follicles were investigated with the surgical operations. As a result, the average number of the collected ovarian follicles were 8.5 and 9.0 in flower deer and elk, respectively. The ovarian follicles collected from each two does were cultured in vitro for 48 hours with m-DMEM medium, and then the cell fusion was carried out after the nuclear transfer by the antler cell. As a result, 5 out of 18 ovarian follicles collected from 2 elk does were reached on the MII stage, but there was no generation resulting from the nuclear transferred embryos by the antler cell after enucleation. In 2 flower does, 7 out of 17 ovarian follicles were reached to the MII stage, but one of them was developed to parthenogenetic embryo as well despite a case of fusion from the nuclear transferred embryo. Embryos were collected in a surgical way on the 7th day after artificial insemination, numbers of average embryos collected were 2.5 and 3.0 in each 2 flower deer and elk does superovulated, respectively. The collected two embryos were transplanted to each 2 does synchronized. As a result, a head of fawn was produced from only one elk doe, where as a head of fawn were delivered from one out of 4 elk does artificial inseminated. Given these findings, we consider that more or less of problems might have occurred in vitro culture system of ovarian follicles in the production of nuclear transfered deer embryos. In addition, the greatest reason why both the aetificial insemination and embryo transfer failed was considered attributable to stress due to anesthesia and catching.
        623.
        2011.10 구독 인증기관·개인회원 무료
        Vollenhovia emeryi chosenica (Wheeler) (Hymenoptera: Myrmicinae) is an ant species frequently found in forests. In nature, two phenotypically distinct forms are found e.g. long winged and short winged. Unlike other hymenopteran insects, the ant is unique in its mode of reproduction. In this species, queens are clonally reproduced from unfertilized eggs. On the other hand, workers develop from fertilized eggs. Strikingly, haploid males are reproduced from fertilized eggs after destroying the maternal half of the genome e.g. maternal genome loss (MGL) consequently only with the paternal half of the genome. We collected the ant colonies nationwide in 2011. In this study, we demonstrate that the ant is infected with Wolbachia, the bacterial reproductive manipulator in various insects. Interestingly, only the long winged morphs seem to be infected. Furthermore, most colonies are mulitple-infected except two colonies collected from Chuncheon and Mt. Deogyu. We will discuss potential interactions among the Wolbachia infection polymorphism and wing morphology, and evolution of clonal reproduction and MGL.
        624.
        2011.10 구독 인증기관·개인회원 무료
        Almost all insect species possess two different acetylcholinesterases (AChE1 and AChE2) but it still remains unknown which AChE plays a major role in synaptic transmission. To predict the evolutionary distributions of functional AChE, relative amount and activity of two AChEs were investigated by native-PAGE in conjunction with Western blotting using AChE1- and AChE2-specific antibodies. Among 39 insect species examined, AChE1 was expressed as the main enzyme in 26 insect species across diverse taxa, suggesting that AChE1 likely plays a more crucial role in these insects. In contrast, AChE2 was predominantly expressed in remaining insect species, including paleopteran insects, suggesting that the replacement of AChE1 function with AChE2 is an old event. As expected, only AChE2 was detected in Cyclorrhaphan flies, supporting the notion that AChE2 in Cyclorrhapha has completely replaced the physiological functions of AChE1 during the evolution of Diptera. Taken together, contrary to the common belief that AChE1 is the major enzyme in most insects, many insect species across various taxa employ AChE2 as the main AChE, suggesting that functional transition from AChE1 to AChE2 has occurred rather universally and randomly with multiple independent origins within the class Insecta. This finding should provide valuable insights into which AChE has evolved to undertake the synaptic function and how functional diversification of AChE has occurred.
        625.
        2011.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        As homework, a total of 32 seventh grade science-gifted students were asked to observe the moon at daily intervals for one month duration. They were also asked to take the photos and to record relevant variables in a given format. The purpose of the task was to investigate what students thought, as they observed the moon. The results show that students paid attention mainly to the position of the moon relative to other variables such as the date in the lunar calendar, the observer's position on the earth, and the position of the sun. Overall students' response implied that students did not observe the lunar phase in relation with relevant variables. Some reponses from students show common misconceptions such as the cause of the lunar phase to reflect the shadow of the earth. However, some responses reveal students' idea that has been rarely reported in the previous researches. For example, some students drew the moon to revolve in the opposite direction. Significant number of students drew the sun's position to be due west before the full moon and due east after the full moon. Few students recognized the relation between the time of observation and observer's position on the earth. The results of current research suggest that not only the education but also the research needs to be expanded to consider informal environment such as the actual field conditions.
        4,000원
        626.
        2011.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        During the last three decades, earth science has been re-conceptualized as an interdisciplinary discipline entitled Earth System Science (ESS), which is based on knowledge of the physical earth system and human impact on the earth. While there is increasing effort to teach earth as a system in K-12 education, teachers' preparedness of to teach earth system is still in its infancy. This article focuses on reviewing the literature of teachers' knowledge of earth systems and of how teachers' knowledge of subject matter affects their teaching practice and pedagogical content knowledge (PCK). First, the study investigated a literature of PCK in general as well as in science teaching. Then this study duscuss what teachers' subject matter knowledge (SMK) is and what it means to be in teaching earth system science. Third, a literature of teachers' knowledge of earth system was reviewed. Finally, a number of suggestions and implications are made as to what teacher education program should do to better prepare future teachers to teach earth systems.
        4,000원
        628.
        2011.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Activated carbon was prepared from pre-carbonized petroleum coke. Textural properties were determined from studies of the adsorption of nitrogen at 77 K and the surface chemistry was obtained using the Fourier-transform infrared spectrometer technique and the Boehm titration process. The adsorption of three aromatic compounds, namely phenol (P), p-nitrophenol (PNP) and benzoic acid (BA) onto APC in aqueous solution was studied in a batch system with respect to contact time, pH, initial concentration of solutes and temperature. Active carbon APC obtained was found to possess a high surface area and a predominantly microporous structure; it also had an acidic surface character. The experimental data fitted the pseudo-second-order kinetic model well; also, the intraparticle diffusion was the only controlling process in determining the adsorption of the three pollutants investigated. The adsorption data fit well with the Langmuir and Freundlich models. The uptake of the three pollutants was found to be strongly dependent on the pH value and the temperature of the solution. Most of the experiments were conducted at pH 7; the pH(PZC) of the active carbon under study was 5.0; the surface of the active carbon was negatively charged. The thermodynamic parameters evaluated for APC revealed that the adsorption of P was spontaneous and exothermic in nature, while PNP and BA showed no-spontaneity of the adsorption process and that process was endothermic in nature.
        4,000원
        629.
        2011.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Seabirds have adapted to life in marine environments. More than 25% of the bird species observed in South Korea are seabirds, using the coast area of Korean peninsula as a stop-over and wintering, and breeding site. The aims of this review are to provide
        4,500원
        630.
        2011.09 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This study explores cross-linguistic differences in online sentence production, working on the theory that the grammatical characteristics of a language customize the speakers’ usual manner of sentence construction and utterance. It is reasoned that a contrast between English and Korean syntax has a direct bearing on that process: The sentential subject is licensed by a tensed verb in English, while it is by an overt morpheme in Korean. This gives rise to a substantial difference in the speakers’ speech patterns: English speakers’ message formation and linguistic encoding center on a verb, while Korean speakers elect or utter a subject first and then draw a predicate. An experiment is conducted on the hypotheses that (a) English L1 speakers are disposed to make sentences based on verbal information, so they would choose a subject that is conceptually more intimate with a given verb; (b) In contrast, Korean L1 speakers’ sentence construction is topic-oriented, so they would first consider the contextual properties of each referent such as shared familiarity and previous topicality; (c) Korean speakers’ L1 patterns would be persistent in their L2 English processing. The results and some implications for English teaching are discussed.
        6,300원
        631.
        2011.06 구독 인증기관 무료, 개인회원 유료
        The development of informatization impacts all sectors, including agriculture. Agricultural informatization builds the knowledge linkage structures of agricultural innovation systems globally. This study investigated the global knowledge linkage structures in agricultural innovation pertinent to information technology (IT) for agricultural research and development (R&D) investments and activities. We explored the longitudinal trend of systemness within the networked research relationships in the triple helix (TH) of the university, industry and government (UIG). We collected data from publications in the Science Citation Index (SCI), the Social Sciences Citation Index (SSCI), and the Arts and Humanities Citation Index (A&HCI) to analyze the TH network dynamics. We also performed a scientometrics analysis to quantitatively identify the knowledge and insights of global agricultural innovation structures. These results could be informative for individual countries. Our findings reveal that the global knowledge linkage structures in the agricultural sector that are pertinent to IT fluctuate widely and fail to increase the capacity of agricultural innovation research due to a neglect of the network effects of the TH dynamics of UIG.
        4,800원
        634.
        2011.05 구독 인증기관·개인회원 무료
        Paratlanticus ussuriensis enter prolonged diapause at an egg stage. Environmental conditions, such as temperature, can modify the diapause duration at initial diapause. Eggs enter initial diapause at 20℃, but continued early embryonic development at 30℃. Final diapause at a fully developed embryonic stage is obligatory regardless of temperature conditions. To determine temperature effects on diapause mechanism of P. ussuriensis eggs, we compared weights, DNA and RNA amounts of eggs incubated at either 20℃ or 30℃ for 50 days after oviposition. Both egg weight and total amount of DNA were constant at 20℃ but gradually increased at 30℃. However, total RNA level was rapidly increased at 15 days-old eggs at 30℃ and maintained high levels during further period whereas its level was constant at 20℃. In addition, we identified three heat shock protein 70 (hsp70a, hap70b, hsp70c) genes of P. ussuriensis and determined those expression levels at different temperature conditions. The levels of hsp70a and hsp70b was not detectable until 20 days after oviposition at both temperature conditions, but highly increased at 50 and 60 days when incubated at 30℃. In contrast, hsp70c level was rapidly peaked at 20 days after oviposition, which is the time of initial diapause entrance. Our results suggest that high temperature breakdown initial diapause and a certain hsp gene, such as hsp70c, may involve in the initial diapause mechanism of P. ussuriensis eggs.
        635.
        2011.05 구독 인증기관·개인회원 무료
        The sweetpotato whitefly, Bemisia tabaci, acts as a vector of more than 100 plant viruses. B. tabaci is known to harbor a primary endosymbiont (Portiera) and 6 secondary endosymbionts (Arsenophonus, Cardinium, Fritschea, Hamiltonella, Rickettsia and Wolbachia). These endosymbionts play important roles in the acquisition and transmission of plant viruses. Using PCR analysis, we identified endosymbiotic bacteria in various B. tabaci populations collected from different places of Korea. Distribution of endosymbionts was different according to the biotype of B. tabaci. Subsequently, their relative densities of endosymbionts were compared between TYLCV-viruliferous and non-viruliferous populations of the Q biotype using quantitative realtime PCR. We found that the densities of Portiera, Cardinium and Hamiltonella are higher in viruliferous than non-viruliferous whiteflies. Our results suggest the role of endosymbiont for the TYLCV transmission of whiteflies.
        636.
        2011.05 구독 인증기관·개인회원 무료
        The soybean aphid, Aphis glycines Matsumura, was recently introduced from Asia into North America (NA) where it has become a serious pest of soybeans. This invasive pest has rapidly spread throughout the midwestern United States and southern Canada since 2000. We examined 585 individuals obtained from 23 different collections in USA, Korea, China, and Japan using eight microsatellite loci. Based on analysis of multilocus genotype, gene diversity and number of alleles in NA were averaging 0.40 and 2.70, whereas in Asia averaging 0.55 and 4.32, respectively. The factorial correspondence analysis displayed that some Korean populations were closely related to the NA populations. Structure analysis resulted in two conspicuous clusters, NA and Asia, as the most likelihood number of clusters (K). Bayesian assignment tests revealed that Osan and Milyang populations were most likely assigned to the NA populations. Bottleneck test did not show significance of genetic bottleneck in all populations. We also discuss the invasive history of the soybean aphid in light of population genetics.
        637.
        2011.05 구독 인증기관·개인회원 무료
        Tetranychid mites are one of the most diverse group including at least 1,200 species in the world. Species identification is difficult due to the small size and similar morphology within the group. We collected 17 species of spider mites from various host plants in different regions of Korea and determined species identity by the comparison of morphological characters and nucleotide sequences of internal transcribed spacer 2 (ITS2) and the cytochrome oxidase subunit I (COI). In addition, we report three new species that were firstly identified in Korea. Amphitetranychus quercivorus (Ehara and Gotoh) was collected from Mongolian oak plant in Daegu, Schizotetranychus miscanthi Saito was from the common reed plant in Ulleungdo, and S. cercidiphylli Ehara was from Bamboo plant in Jeju. Morphological identification of three species were similar with those of Japanese samples, but the ITS2 and COI sequences of A. quercivorus and the COI sequence of S. miscanthi were different with Japanese species at the rates of 1/419, 2/331 and 3/332 nucleotides, repsectively. S. cercidiphylli can be identified by the aedeagus shape of males but we firstly sequenced ITS2 and COI of this species. Our results can be used for the identification of spider mites which are important in plant quarantine.
        638.
        2011.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We report the results of our high resolution optical spectroscopic monitoring campaign (⋋ = 3800 ~ 8800 Å, R = 30000 - 45000) of the new FU Orionis-type object HBC 722. We observed HBC 722 with the BOES 1.8-m telescope between November 26 and December 29, 2010, and FU Orionis itself on January 26, 2011. We detect a number of previously unreported high-resolution K I and Ca II lines beyond 7500 Å. We resolve the Hα and Ca II line profiles into three velocity components, which we attribute to both disk and outflow. The increased accretion during outburst can heat the disk to produce the relatively narrow absorption feature and launch outflows appearing as high velocity blue and red-shifted broad features.
        4,000원
        639.
        2010.12 구독 인증기관 무료, 개인회원 유료
        우리나라 다큐멘터리의 강점과 문제점, 유통 현황과 대응 전략 등을 알아보기 위해, 전문가 심층인터뷰와 SWOT 분석을 통해 연구결과를 도출했다. 국내 다큐의 강점으로는 휴먼, 시사 다큐, 리얼리티 프로그램의 강세가 꼽혔고, 약점으로는 전문 기획역량이 부족한 점, 낮은 제작비와 짧은 제작기간, 소재의 다양성 부족, 포스트 프로덕션 작업의 취약성 등이 지적됐다. SWOT 조건에서 취할 수 있는 각각의 경쟁 전략을 도출해 본 결과, 강점⦁기회전략으로는 플랫폼 다각화에 따른 차별적인 다큐 제작과 HD 환경에 적합한 킬러 콘텐츠 제작의 필요성, 강점⦁위협전략으로는 정부의 해외공동제작 지원과 해외 영화제 및 마켓 참가 지원 등이 꼽혔다. 반면, 약점⦁기회전략으로는 다큐멘터리 전문제작 인력의 양성, HD 제작기반 시설에 대한 지원, 포스트 프로덕션에 대한 투자, 유통 전문가 양성 등, 약점⦁위협전략으로는 저작권 문제 해결, 다큐 제작 지원을 위한 펀드 조성 등이 시급한 전략으로 나타났다. 앞으로 우리나라에서 전문적으로 다큐 프로그램을 기획하고 다큐 포맷을 유통시킬 수 있는 독립적인 회사가 필요하다. 독창적인 기획을 가지고 이를 체계적인 포맷으로 가공한다면, 우리의 콘텐츠를 해외 시장에 전파할 수 있는 다양한 기회를 잡을 수 있을 것이다.
        7,800원
        640.
        2010.12 구독 인증기관 무료, 개인회원 유료
        The effects of isotonic saline on corneal penetration, thickness, and injury, as well as lacrimal secretion in a rat model of dry eye were investigated, in comparison with distilled water. Male Sprague-Dawley rats received intraperitoneal administration of atropine sulfate (20 mg/kg) and their eyes were exposed to dry (relative humidity 25-35%) air flow (2.4 m/sec), under Zoletil anesthesia, for 5 hr to induce dry eye. During the period of dry eye induction, distilled water or isotonic saline (5 μl) was instillated onto the cornea every 30 min. Corneal penetration was measured through fluorescein dye quantification, and corneal thickness and injury were examined under a microscope. Lacrimal (tear) secretion and mucin-like glyocoprotein excretion from goblet cells were measured using the Schirmer test and microscopy, respectively. In dry eye rats treated with distilled water, corneal thickness, tear secretion, and mucin-like glycoprotein excretion were decreased to 74.0%, 74.1%, and 46.3% of normal levels, respectively, resulting in marked corneal injury and a significant increase in corneal penetration. In comparison, treatment with isotonic saline resulted in recovery of lacrimal secretion, in spite of a slight improvement of mucin-like glycoprotein excretion, and thereby prevented corneal penetration of fluorescein by 10%. The results indicate that repeated instillation of isotonic saline could provide slightly greater protection from corneal injury, compared with distilled water by facilitating lacrimal secretion, in addition to relief of inconvenience and pain.
        4,000원