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        검색결과 13

        6.
        2008.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The studies on integrated operation of fuel cell with fuel processor are very essential prior to its commercialization. In this study, Polymer Electrolyte Membrane Fuel Cell (PEMFC) was operated with a fuel processor, which is mainly composed of two parts, methanol steam reforming reaction and preferential oxidation (PROX). In fuel processor, ICI 33-5 (CuO 50%, ZnO 33%, Al2O3 8%, BET surface area: 66 m2g-1) catalyst and CuO-CeO2 catalyst were used for methanol steam reforming, preferential oxidation (PROX) respectively. PEMFC was operated by hydrogen fuel generated from fuel processor. The resulting gas from PROX reactor is used to operate PEMFC equipped with our prepared anode and cathode catalyst. PtRu/C catalyst gives more tolerance to CO.
        4,000원
        7.
        2018.06 KCI 등재 서비스 종료(열람 제한)
        The phenotypic traits of 63 Asian plum varieties were investigated for three years to select those with superior qualities for breeding. Eight morphological characteristics of the flowers and fruits (e.g., stigma position, fruit skin, and flesh color) were evaluated. Phenological characteristics (e.g., blooming time and ripening time) were also monitored. Being useful traits for breeding, fruit quality factors (e.g., fruit weight, skin color, flesh color, soluble solids content, and titratable acidity) were evaluated as well. The majority of the fruits were cordate (36%) and circular (23%) in shape. Approximately 78% of the varieties showed a red skin color, whereas 67% had yellowish fruit flesh. Fruit ripening occurred from June 28th to September 5th, spanning 69 days. The average fruit weight and soluble solids content were 77.2 g and 12.2 °Brix, respectively. Regarding correlations among the characteristics, the most significant correlation coefficients were for the ripening time and fruit size parameters. Such information of Asian plum varieties will be useful for future breeding programs.
        8.
        2015.09 서비스 종료(열람 제한)
        Red spotted grouper (Epinephelus akaara) is one of the most popular and important grouper species for aquaculture in South-East and East Asia thanks to its fast growth and high market value. This species is known as a protogynous hermaphrodite which first differentiates into females and changes to males later. Natural sex change in this species occurs at 2 or 3 years of age. Many studies have been conducted, so far, to develop standardized methods for artificial sex reversal by treatment with sex steroid hormones (Bhandari et al., 2005; Lee et al., 2014). However, sex-changed male groupers showed testes with ovarian cavity, and their sperm production was very low. Induction of primary sex differentiation directly into males would be an alternative approach. Identification of the exact primary sex differentiation period is the prerequisite for this approach. Red spotted grouper were reared in indoor tanks and acclimatized at 25±2℃ under natural photoperiod. Fish were sampled at 60 days after hatching. The samples were processed for histological analysis using standard techniques in an automatic tissue processor, sectioned at 8 μm in thickness and stained with haematoxylin and eosin. The result of this study shows the morphological characteristics of gonadal primordium, and suggests that the timing of gonadal differentiation in red spotted grouper is at least 10 days earlier than the previous study of Lee et al. (2014) which observed gonadal primordium at 70 days after hatching.
        9.
        2013.08 서비스 종료(열람 제한)
        Gonadotropin-inhibitory hormone (GnIH) has been found to inhibit the synthesis and release of gonadotropin (GTH) in avian and mammalian species. It was originally identified in the brain of a quail as a novel hypothalamic neuropeptide with a C-terminal Arg-Phe-NH2 motif (RFamide peptide). Homologs of this peptide have been identified in a couple of model fish species such as goldfish (Carassius auratus) and zebrafish (Danio rerio). Understanding GnIH system could be particularly useful in some aquaculture species with problems of frequent reproduction and/or precautious sexual maturation. However, GnIH system in such species has not been studied yet. In this study, we have identified a pupative GnIH gene in the Nile tilapia (Oreochromis niloticus). We also investigated the role of GnIH in the reproduction of this species. The full length sequence of putative tilapia GnIH gene coded for a protein (197 amino acids) containing two modified RFamides (MPLRF and LSQRF) and a LPQRF cDNA sequence of 594 bp. This putative GnIH gene showed high homology with the GnIH genes of Takifugu rubripes (72%) and Tetraodon nigroviridis (74%). PCR analysis showed that expression of this gene was ubiquitously distributed in the whole brain, ovary and testis as well as in the peripheral tissues examined in this study (liver, kidney, intestine, spleen, muscle and gill) except heart and eye. Expression level of this gene in sexually inactive group was significantly higher than the expression level in first gonadal development and sexually active groups (P<0.05). On the contrary, the expression level of LH-β gene was low in sexually inactive group but significantly higher in first gonadal development and sexually active groups (P<0.05). However, no significant difference was observed in the level of FSH-β gene expression between different reproductive phases in this species. In vitro studies revealed an inhibitory effect of GnIH on LH-β mRNA and FSH-β mRNA levels. No significant difference between GnIH and GnIH with LHRH-a treatments on LH-β and FSH-β mRNA expression in female tilapia pituitary cells.
        10.
        2011.03 KCI 등재 서비스 종료(열람 제한)
        In the present study, embryoid bodies (EBs) obtained from induced pluripotent stem cells (iPSCs) were induced to differentiate into germ lineage cells by treatment with bone morphogenetic protein 4 (BMP4) and retinoic acid (RA). The results were compared to the results for embryonic stem cells (ESCs) and multipotent spermatogonial stem cells (mSSCs) and quantified using immunocytochemical analysis of germ cell-specific markers (integrin-, GFR-, CD90/Thy1), fluorescence activating cell sorting (FACS), and real time-RT-PCR. We show that the highest levels of germ cell marker-expressing cells were obtained from groups treated with 10 ng/ BMP4 or 0.01 RA. In the BMP4-treated group, GFR- and CD90/Thy-1 were highly expressed in the EBs of iPSCs and ESCs compared to EBs of mSSCs. The expression of Nanog was much lower in iPSCs compared to ESCs and mSSCs. In the RA treated group, the level of GFR- and CD90/Thy-1 expression in the EBs of mSSCs Induced pluripotent stem cells, Mouse embryonic stem cells, Multipotent spermatogonial stem cells, Germ cell lineage, Differentiation potential. was much higher than the levels found in the EBs of iPSCs and similar to the levels found in the EBs of ESCs. FACS analysis using integrin-, GFR-, CD90/Thy1 and immunocytochemistry using GFR- antibody showed similar gene expression results. Therefore our results show that iPSC has the potential to differentiate into germ cells and suggest that a protocol optimizing germ cell induction from iPSC should be developed because of their potential usefulness in clinical applications requiring patient-specific cells.
        11.
        2010.09 서비스 종료(열람 제한)
        Photoperiod is known to be the most potent environmental stimulus for reproduction in many lower vertebrates, and it exerts an endogenous effect by causing a rhythmic change in melatonin level, which increases during the dark phase and decreases during the light phase. In recent studies, melatonin administration was capable of changing seasonal reproductive activities in several fish species, and also resulted in modulating the timing of smoltification in a salmonid fish (Amano et al., 2004; Ligo et al., 2005). In this study, we have investigated the changes of spawning activities (number of eggs, frequency of spawning) by oral administration of melatonin in the Nile tilapia, Oreochromis niloticus. Fish were obtained from a local fish farm (Chungju, Chung Buk) and acclimatized in fish rearing facilities in Sunmoon University (Asan, Chung Nam). Randomly selected 24 fishes (12 males, 12 females; 200~400 g in body weight, BW) were divided into three groups and each fish was accommodated into glass aquarium individually. Fish were fed either with control diet (0 ㎎ melatonin) or low-dose melatonin diet (0.3 ㎎ melatonin/㎏, BW) or high-dose melatonin diet (3 ㎎/㎏, BW). Fish were individually checked everyday for the presence of eggs in their mouths, and the eggs were removed and counted when found. Fish were fed twice a day, but melatonin treated diet was given only once a day at 10:00a.m.. The daily feeding ration was set at 2% of the body weight so that the fish ate all the pellets provided. Fish were sampled for blood parameters (Hb, Glu, GOT, GPT) on March 2 (Day 30), April 2 (Day 60), May 3 (Day 90), June 3 (Day 120) and July 14 (Day 160). The sampling was done between 14:00 and 16:00 p.m.. For the sampling, fish were anesthetized in 50 ppm benzocaine, and body length (BL) and BW were measured. Blood sample was collected using a heparinized syringe from the caudal blood vessel. Melatonin affects several photoperiodic signals including reproductive activities in fish. Low-dose melatonin administration appeared to disturb spawning and sexual maturation in Nile tilapia in this study. Fish treated with low-dose melatonin spawned less numbers of egg than the fish treated with high-dose. In contrast, high-dose melatonin administration caused more frequent spawning than low-dose melatonin. On the other hand, somatic growth and blood parameter were not affected by melatonin treatments. These results suggest that pertinent melatonin could be involved in providing photoperiodic information as short day photoperiod. Fish treated with over dose melatonin seemed to have no melatonin-free interval. In that circumstance the melatonin message might have not been conveyed as a proper signal.
        12.
        2009.06 KCI 등재 서비스 종료(열람 제한)
        Randomly Amplified Polymorphic DNA (RAPD) was performed to define the genetic variation and relationships of Artemisia capillaris. Fifteen populations by the distributions and habitat were collected to conduct RAPD analysis. RAPD markers were observed mainly between 300bp and 1600bp. Total 72 scorable markers from 7 primers were applied to generate the genetic matrix, and 69 bands were polymorphic and only 3 bands were monomorphic. The genetic dissimilarity matrix by Nei's genetic distance (1972) and UPGMA phenogram were produced from the data matrix. Populations of Artemisia capillaris were clustered with high genetic affinities and cluster patterns were correlated with distributional patterns. Two big groups were clustered as southern area group and middle area group. The closest OTUs were GW2 and GG1 in middle area group, and GB1 from southern area group was clustered with OTUs in middle area group. RAPD data was useful to define the genetic variations and relationships of A. capillaris.
        13.
        1999.06 서비스 종료(열람 제한)
        Molecular markers are useful to confirm the hybridity of F1 plant derived from cross of two homozygous parents with similar morphological traits. RAPD markers were used to test F1 hybrid plant obtained from cross of two homozygous soybean (Glycine max) parents. Fl plant for cross I was made from the mating of Hobbit87 (female) and L63-1889 (male) and Fl plant for cross II was obtained from the mating of H1053 (female) and L63-1889 (male). Selfing plant per each cross was also obtained. Among 20 Operon primers used, OPA04 and OPA09 show polymorphism between cross I and II parent. Band in size 1Kb of OPA04 and 2.1Kb of OPA09 primer was polymorphic band. This fragment identified Fl hybrid plant and selfing plant in cross I and II. Female parent Hobbit87 in cross I and H1053 in cross II has no this fragment (recessive allele). However, male parent L63-1889 and Fl hybrid plant in cross I and II has this size of polymorphic band (dominant allele). This indicated that Fl hybrid and selfing plants were detected by RAPD marker before phenotypic marker would be used to identify Fl hybridity. Amplification products of selfing plant for cross I and II were completely same to the those of female parent. When mature, flower color of Fl hybrid plant in cross I and II was purple and flower color of selfing plant in cross I and II was white. Purple flower is dominant trait. Fl hybridity was successfully detected at very early growth stage using RAPD marker. Therefore, RAPD marker can be used broadly to confirm Fl hybridity in many crops.