• Applied Microscopy
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• v.41 no.4
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• pp.249-255
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• 2011

Neurons utilize a large quantity of energy for their survival and function, and thereby require active mitochondrial function. Mitochondrial morphology shows dynamic changes, depending on the cellular condition, and mitochondrial dynamics are required for neuronal development and function. In this study, we found that the length of mitochondria in the distal axon is significantly shorter than that of mitochondria in dendrites or proximal axons of cerebral cortical neurons, and the reason for this difference is the local fission within the axon. We also found that suppression of Drp1, a key regulator of mitochondrial fission, resulted in significant elongation of mitochondria in axons. Collectively, these results suggest that local mitochondrial fission within the axon contributes to region-dependent mitochondrial length differences in the axons of cortical neurons.

• Applied Microscopy
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• v.41 no.3
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• pp.163-168
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• 2011

Tiger barb (Puntius tetrazona Bleeker, 1855) is a teleost belonging to Cyprinidae. The oogenesis of tiger barb was investigated by light microscope. The ovary was of white and ellipsoidal shape with the major axis 2 cm and the minor axis 1 cm. Cytoplasm of oogonia was basophilic and many nucleoli were located at inside of nuclear membrane. In early stage of primary oocyte, yolk vesicles were distributed only in the marginal area. In secondary oocyte, the egg envelope was formed and yolk vesicles was formed in the cytoplasm. The basophilic substance of cytoplasm was changed to acidic. In case of matured egg, thickness of egg envelope and size of egg were increased. The yolk vesicles were changed to yolk mass in accordance with development. Also, there is not the formation of oil droplets in cytoplasm. In conclusion, the oogenesis of tiger barb was characterized by the increase in cell size, the formation of yolk, the decrease of basophilic substance in the cytoplasm, and formation of yolk mass.

• Applied Microscopy
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• v.41 no.3
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• pp.155-161
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• 2011

Three spot gourami (Trichogaster trichopterus Pallas, 1770) is a teleost belonging to Belontiidae. The oogenesis of three spot gourami was investigated by light microscope. The ovary was of light peach color and ellipsoidal shape with the major axis 2 cm and the minor axis 1 cm. Cytoplasm of oogonia was basophilic and many nucleoli were located at inside of nuclear membrane. In primary oocyte, lipid droplets were distributed only in the marginal area first, than at nuclear envelope near. In secondary oocyte, the egg envelope was formed and yolk vesicles was formed in the marginal area. The basophilic substance of cytoplasm was changed to acidic. In case of matured egg, thickness of egg envelope and size of egg were increased. The yolk vesicles were changed to yolk mass in accordance with development. The fertilized eggs were the colorless, transparent, spherical, adhesive and pelagic type. A large oil droplet was located in vitelline membrane of the fertilized egg. In conclusion, the oogenesis of three spot gourami was characterized by the increase in cell size, the formations of lipid droplets and yolk, the decrease of basophilic substance in the cytoplasm, and formation of one large oil droplets.

• Journal of Life Science
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• v.15 no.3 s.70
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• pp.434-438
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• 2005

In the previous study, we isolated a myulchikinase (MK), which has fibrinolytic activity and cytotoxicity to the tumor cell line, from myl- chi-jeot-gal. In this study, the effect of NaCl concentration, metallic ions, pH, temperature, and plasminogen on the activity of MK was analysed. The MK activity was maintained at least $80\%$ activity up to $30\%$ NaCl, which indicates that the enzyme may be halotolerant. The optimal pH and temperature were 8 and $40^{\circ}C$, respectively. The fibrinolytic activity of MK was completely inhibited with 0.5 mM $Hg^{2+}$ and inhibited to $50^{\circ}C$ with 1 mM $Cu^{2+}\;and\;Zn^{2+}$. The MK showed strong activity in plasminogen- rich fibrin plate but not in plasminogen-free fibrin plate. The result indicates that the MK may be a plasminogen activator type fibrinolytic enzyme.

• Reproductive and Developmental Biology
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• v.30 no.1
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• pp.59-64
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• 2006

This study was conducted to establish a convenient freezing method of boar semen. Boar semen was cooled until $5^{\circ}C$ for 3 hrs using cell freezer and loaded into straws. Semen straws were frozen in different steps in strofoam box filled with $LN_2$. Highest sperm viability (54.0%) was obtained by 1-step freezing(holding at 10 cm height from the surface of $LN_2$ for 10 min). Sperm viability increased by holding at $-102^{\circ}C$ for 10min (74.0%, P<0.05). In thawing regime, sperm viability was significantly higher in $37^{\circ}C$ group than in $52^{\circ}C$ group. The sperm characteristics did not differ between 1-step and 3-step. After IVF using frozen-thawed boar semen, developmental rate of embryos to the morula+blastocyst stage was in 1-step freezing group than that of 3-step freezing group (27.5 vs 14.7%, P<0.05). The result shows that the 1-step freezing with holding at $-102^{\circ}C$ for 10min before plunging into $LN_2$ is a convenient and easy freezing method for boar semen.

• Reproductive and Developmental Biology
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• v.30 no.1
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• pp.47-52
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• 2006

This study was conducted to examine whether the parthenogenetic mouse embryonic stem (P-mES) cells can differentiate into functional cardiomyocytes in vitro similar to (mES) cells. p-mES04 and IVF-derived mES03 cells were cultured by suspension culture for 4 days. The formed embryoid bodies (EBs) were treated with 0.75% dimethyl-sulfoxide (DMSO) for further 4 days (4-/4+), and then plated onto gelatin coated culture dish. The appearance of contracting cardiomyocytes from the P-mES04 and mES03 cells was examined for 30 days. The highest cumulative frequency was detected at days 13 (69.83%) and 22 (61.3%), respectively. By immunocytochemistry, beating P-mES04 cells were positively stained with muscle specific anti-sarcomeric a-actinin Ab and cardiac specific anti-cardiac troponin I Ab similar to contracted mES03 cells. When the expression of cardiac muscle-specific genes was analyzed by RT-PCR, beating P-mES04 cells were expressed cardiac specific L-type calcium channel, a1C, cardiac myosin heavy chain a, cardiac muscle heavy polypeptide $7{\beta}$, GATA binding protein 4 and atrial natriuretic factor, but not expressed skeletal muscle specific L-type calcium channel, a1S, which was similar to male adult heart cells and mES03-derived beating cardiomyocytes. The result demonstrates that the P-mES cells can be used as an alternative for the study on the characteristic analysis of in vitro cardiomyocyte differentiation from the ES cells.

• Applied Microscopy
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• v.28 no.1
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• pp.39-48
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• 1998

The spermatozoa of bagrid catfish, Pseudobagrus fulvidraco are approximately $76{\mu}m$ in length, and a relatively simple and elongated cell composed of a spherical head, a short middle piece and a tail. The ultrastructure of spermatozoa of P. fulvidraco is characterized by the following features. The acrosome is absent as in most teleost. The round nucleus measuring about $1.67{\mu}m$ in length and diameter is depressed with a deep nuclear fossa. The nuclear fossa, the length of which is about three-fifths of the nuclear diameter, contains the proximal and distal contrioles. The two centrioles are oriented approximately $160^{\circ}$ to each other. The filamentous materials give rise to satellite appendages arranged tangentially from the triplets of the distal centriole and the doublets of the anterior end of the axoneme toward the nuclear envelope. The mitochondria are not fused and their number is 20 or more. They are arranged in two or three layers and two rings within the cytoplasmic collar and surround the axoneme. They are separated from the axoneme by the cytoplasmic canal. The axoneme is of the 9+2 microtubular pattern and has inner but no outer dynein arms. The two lateral fins are in the same plane with the two central microtubules, the doublets 3 and 8, which are ultrastructural characteristics of the sperm tail unlike other siluroids lacking the lateral fins.

• Korean Journal of Ecology and Environment
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• v.39 no.2 s.116
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• pp.209-218
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• 2006

This study was to evaluate microcystin production by two strains of cyanobacteria (Microcystis aeruginosa and Planktothrix agardhii) in response to three different levels of direct (0,4,8 inds.) or indirect (0,25, 50% of zooplankton culture media filtrate) exposures to zooplankton (Daphnia magna and Moina macrocopa). The cell biomass and intracellular microcystin (MC) were measured everyday. The survival rates of zooplankton were evaluated for daily intervals for the direct exposure. The intracellular MC produced peaked on the day 3 or 4, and then decreased over the both exposure experiment. In the direct experiment, the MC values were significantly different among the control and zooplankton treatments (ZT; repeated measures-ANOVA: P< 0.039). The MC contents of P. agardhii strain (No.204) were significantly higher (Tukey test, P< 0.082) in ZT2 (8 inds.) than in ZT2 (4 inds.). On the peak day, the intracellular MC exposed to both zooplanktons was significantly higher than the control (One-way ANOVA, P< 0.021). Higher zooplankton survivals were observed in the M. aeruginosa strain (No. 111) rather than in high toxic P. agardhii strain. In the indirect experiment, the intracellular MC of the M. aeruginosa strain was significantly different among the control and zooplankton culture media filtrate (ZCMF)treatments (rm-ANOVA: P<0.004), The MC exposed ZCMF2 (50%) were significantly higher than in ZCMFI (25%: Tukey test, P< 0.025) for both strains. This study strongly supports the induced-defensive MC production of potentially toxic cyanobacteria in response to the presence of zooplankton.

• Journal of Life Science
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• v.25 no.5
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• pp.568-576
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• 2015

The marine microalga Pavlova viridis can grow fast and has the ability to accumulate essential nutrients for culturing marine animals, such as EPA and DHA, and it has been used as food for raring larval fish and prawn. The symbiotic relationship between the flagellate microalga Pavlova viridis and its associated bacteria was investigated. An axenic culture of P. viridis was obtained by repeated treatment of the microalga with an antibiotic cocktail. The axenic status was confirmed after sub-culturing three times in a sterile f/2 medium without an antibiotic. The axenic alga was then co-inoculated with five bacteria, arbitrarily designated as I1–I5, isolated from the alga to test the growth promotion of the algae. All bacterial strains promoted the growth of P. viridis, and bacterial isolate I3 was the most effective among the five bacteria tested. The cell number of P. viridis in the co-culture with I3 was significantly higher than that of the control culture. A sequence analysis of the 16S rRNA gene isolated from I3 revealed a 97% nucleotide sequence similarity to that of Citrobacter sp. The growth of strain I3 was also significantly enhanced by co-culturing with P. viridis, indicating a symbiotic relationship between the microalga and its associated bacterium. The association between the microalga and bacterium was confirmed by scanning electron microscopy.

• Journal of Life Science
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• v.21 no.7
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• pp.997-1003
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• 2011

Menopause and obesity are associated with metabolism. The purpose of this study was to examine the changes of PPAR${\gamma}$, PGC-1(${\alpha},\;{\beta}$), NRf-1 and TFAM mRNA and mitochondria biogenesis in adipocytes and investigate the effect of swimming exercise for 6weeks on ovariectomized rats. Rats were randomly assigned to 3 groups: (1) ovariectomized rats fed with a control diet (C, n=4), (2) ovariectomized rats fed with high fat diet (H, n=4), and (3) ovariectomized rats trained to exercise and fed with high fat diet (H+EX, n=4). Exercise was performed by swimming for 5 days/wk, with a progressive increase in exercise over the course of 6 weeks. Results showed that the fat tissue weight in the H group was markedly increased (p<0.01) compared to other groups, however, regular exercise significantly decreased fat weight. The PPAR-${\gamma}$ (p<0.05), PGC-$1{\alpha}$ (p<0.01), -$1{\beta}$ (p<0.05), NRf-1 (p<0.01) and TFAM (p<0.05) mRNA expression in the adipocytes of H+EX were higher than in the H group. These results suggest that regular exercise for 6 weeks might exert positive effects by increasing PPAR-${\gamma}$, PGC-1 (${\alpha},\;{\beta}$), NRf-1 and TFAM mRNA expression and mitochondria in adipocytes. Thus, regular exercise may be helpful in the improvement of mitochondria biogenesis function in obese, ovariectomized rats.