• Journal of Life Science
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• v.9 no.5
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• pp.518-524
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• 1999

Timing of oviposition, nuclear maturation of oocytes, egg-sperm contact and brooding were observed in the giant fresh-water prawn Macrobrachium rosenbergii reared in the laboratory. When a pre-spawning molted female was transferred to the male, the female oviposited commonly at 5 to 10 hr after mating. The first polar body were extruded within 2-3 min after spawning. The egg chromosome progressed to release second polar body by 30 min and mitotic nuclear division occurred in 8 hr after spawning. Thumbtack-shaped spermatozoa were seen peneterating egg membrane with their spike directed forward. Transformation of spermatozoa and fertilization membrane could not be observed by light microscopy. The elapsed hours from oviposition to the end of brooding wee taken in 5-7 hr. Brood size for female 9 cm and 18 cm in body length was estimated to be 10,000~15,000 and 100,000 eggs, respectively and is proportional to the total length of the berried females. The ovigerous females reared at chlorinity of 2.21~4.25$\textperthousand$Cl. showed a normal egg development up to hatching.

• Journal of Plant Biology
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• v.30 no.4
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• pp.225-247
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• 1987

Meiosis and postmeiotic mitosis in Boletus rubinellus were examined ultrastructurally. Meriosis occurred at the apex of the basidium. A sausage-shaped spindle pole body(SPB) was observed along with the presence of synaptonemal complexes during pachytene and a diglobular SPB was present on late pachytene or diplotene nuclei. During metaphase I, the monoglobular SPB at the spindle pole was surrounded bya membrane and the nuclear enveloope was discontinuous. At anaphase I, the chromosomes became better defined and formed a central spindle. The nucleolus was extruded from the nucleus. During anaphase I, the SPB was excluded from the chromosomal region by a membrane and both poles were fully separated to opposite sides of the basidial wall. In meiosis II, the two nuclei divided synchronously and the spindles were parallel. The spindles were smaller than in meiosis I, while the SPB was approximately the same size as that of the similar stage in meiosis I. During anaphasetelophase II, the SPB was surrounded by a cap of endoplasmic reticulum (ER) that delimited it from the spindle. The postmeiotic interphase nuclei migrated to the mid-region of the basidium before migration to the spores. The SPB at this stage was diglobular. A postmeiotic mitosis occurred within the basidiospore, and the plane of the spindle was obique to the long axis of the spore. The spindle and SPB were smaller than at meiosis I and there were fewer nonchromosomal microtubules. At anaphase, the nucleolus was present inside the nuclear envelope but lateral to the spindle.

• Korean Journal of Microbiology
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• v.10 no.1
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• pp.29-34
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• 1972

The present study is of ultra-fine structure of Cryptococcus neoformans by means of electron microscopy and reveals the following : 1) In constrast to the bacteria, the normal Cryptococcus neofrmans contains nuclear enveloped with nuclear menbrane, mitochondria, endoplasmic reticulum, distinct cell wall and cell membrane, vacuoles and storage granules as observed in the eucaryotic cells. 2) In apparent cell walls and cell membrane with the appearance of electron transparent area (ETA) and changes of cell morphology were observed in the ultra-violet ray irradiated cell. 2) In apparent cell walls and cell membrance with the appreance of electron transparent area (ETA) and changes of cell morphology were observed in the ultra-violet ray irradiated cell. 3) Morphology changes and cytoplasmic element abnormality was increased with irradiated time. 4) Increase of electron transparent area was thought to be associated with degradation of cell.

• Applied Microscopy
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• v.5 no.1
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• pp.1-8
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• 1975

These studies were carried out the observation of polymorphonuclear leukocyte phagocytosis of Candida albicans in vitro and also detected to the cytoplasmic changes of polymorphonuclear leukocyte during phagocytosis by the method of electron microscopy. The results were summarized as follows: 1. In normal polymorphonuclear leukocyte, nuclear lobes showed a preponderance of dense, granular chromatin located peripherally. The cytoplasm of polymorphonuclear leukocyte was not extensive; the cytoplasmic matrix was moderate dense and of a granular appearance. Golgi complex and rough endoplasmic reticulum system was poorly developed. But a various type of granules were seen abundantly. 2. After 30 minutes of incubation, Candida albicans was completely engulfed. These had come to lie in the vacuole which was limited by the membrane. 3. After 90 minutes of incubation, the phagocytic vacuoles were larger, and many granules devoid of membranes were seen within them. Though the granules has lost their membrane after entering the vacuoles. 4. After 2 hours of incubation, the cytoplamsic components of polymorphonuclear leuko cytes were changed their original morphology.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.3
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• pp.209-218
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• 2022

Recently, research on the development of anion exchange membranes (AEMs) has received considerable attention from the scientific community around the world. Here, we fabricated a series of AEMs with branched structures with different alkyl spacers and conducted comparative evaluations. The introduction of these branched structures is an attempt to overcome the low ionic conductivity and stability problems that AEMs are currently facing. To this end, branched polymers with different spacer lengths were synthesized and properties of each membrane prepared according to the branched structure were compared. The chemical structure of the polymer was investigated by proton nuclear magnetic resonance, Fourier transform infrared, and gel permeation chromatography, and the thermal properties were investigated using thermogravimetric analysis. The branched anion exchange membrane with (CH₂)₃ and (CH₂)₆ spacers exhibited ionic conductivities of 8.9 mS cm^-1 and 22 mS cm^-1 at 90℃, respectively. This means that the length of the spacer affects the ionic conductivity. Therefore, this study showing the effect of the spacer length on the ionic conductivity of the membrane in the polymer structure constituting the ion exchange membrane is judged to be very useful for future application studies of AEM fuel cells.

• Membrane Journal
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• v.34 no.2
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• pp.114-123
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• 2024

Hydrogen isotopes can be categorized into light hydrogen, heavy hydrogen, and tritium based on the number of neutrons, each of which is used in specific fields. Specifically, deuterium is of interest in the electronics industry, nuclear energy industry, analytical technology industry, pharmaceutical industry, and telecommunications industry. Conventional methods such as cold distillation, thermal cycling absorption processes, Girdler sulfide processes, and water electrolysis have their own advantages and disadvantages, leading to the need for alternative technologies with high separation and energy efficiency. In this context, membrane-based hydrogen isotope separation is one of the promising solutions to reduce energy consumption. In this review, we will present the state-of-the-art in hydrogen isotope separation using membranes and their operating principles. The technology for separating hydrogen isotopes using membranes is just beginning to be conceptualized, and many challenges remain to be overcome. However, if achieved, the economic benefits are expected to be significant. We will discuss future research directions for this purpose.

• Applied Microscopy
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• v.30 no.4
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• pp.389-401
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• 2000

The mouse for identifying the histological changes of kidney were also divided into the two groups; treated with only $HgCl_2$ (4 mg/kg), the group treated with $HgCl_2$ and squalene (200 mg/kg). The $HgCl_2$ treated only one time at first day. The squalene treated two times a day (12 hours interval) for every day. Each groups were divided into the five groups; 6, 12, 24, 48 and 72 hours after treated $HgCl_2$ and squalene. Historical changes of the kidneys were investigated by electron microscope. The group with only $HgCl_2$ showed that the nuclear membrane was shrinked, the inner membrane (cristae) of the mitochondria were destructed, and ribosomes on the rough endoplasmic reticulum were lost. The group treated with $HgCl_2$ and Squalene showed that the nuclear membrane was more rounded, the cristae of the mitochondria were almost normal shape, and more ribosomes on the rough endoplasmic reticulum were attached. Therefore , we concluded that squalene has significantly protective effects in kidney to harmful $HgCl_2$.

• Natural Product Sciences
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• v.26 no.3
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• pp.191-199
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• 2020

Fucoidan, a natural component of brown seaweed, has various biological activities such as anti-cancer activity, anti-oxidant, and anti-inflammatory against various cancer cells. However, the fucoidan has been implicated in melanoma cells via apoptosis signaling pathway. Therefore, we investigated apoptosis with fucoidan in A2058 human melanoma cells with dose- and time-dependent manners. In our results, A2058 cells viability decreased at relatively short-time and low-concentration through fucoidan. This effects of fucoidan on A2058 cells appeared to be mediated by the induction of apoptosis, as manifested by morphological changes through DNA-binding dye Hoechst 33342 staining. When a dose of 80 ㎍/mL fucoidan was treated, the cells were observed: crescent or ring-like structure, chromatin condensation, and nuclear fragmentation. With the increase at 100 ㎍/mL fucoidan, the cell membrane is intact throughout the total process, including membrane blebbing and loss of membrane integrity as well as increase of sub-G1 DNA. Furthermore, to understand the exact mechanism of fucoidan-treated in A2058 cells, western blotting was performed to detect apoptosis-related protein expression. In this study, Bcl-2 family proteins can be regulated by fucoidan, suggesting that fucoidan-induced apoptosis is modulated by intrinsic pathway. Therefore, expression of Bcl-2 and Bax may result in altered permeability, activating caspase-3 and caspase-9. And the cleaved form of poly ADP-ribose polymerase was detected in fucoidan-treated A2058 cells. These results suggest that A2058 cells are highly sensitive to growth inhibition by fucoidan via apoptosis, as evidenced by activation of extracellular signal-regulated kinases/p38/Bcl-2 family signaling, as well as alteration in caspase-9 and caspase-3.

• The Korean Journal of Nuclear Medicine
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• v.32 no.4
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• pp.305-313
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• 1998

The reduction in the amount of asialoglycoprotein (ASGP) receptor, which resides exclusively on the plasma membrane of functioning mammalian hepatocytes, as a consequence of hepato-cellular damage has been demonstrated in various pathologic conditions of the liver. Galac-tosylated human serum albumin (GSA) is a newly developed receptor-binding agent, specific for the ASGP receptor. Tc-99m GSA binds quantitatively to liver ASGP receptors and the rate of accumulation in the liver is dependent on hepatic function represented as the amount of receptor, as well as the amount of ligand injected, its affinity to the receptor and the hepatic blood flow. The findings of Tc-99m GSA scintigraphy were reported to reflect the hepatic function of the patients with large hepatic tumors, obstructive jaundice, acute and chronic liver disease. Tc-99m GSA scintigraphy is an easy and reliable test and has the clinical potentials to evaluate the liver function in the patients with hepatic disorders.

• The Korean Journal of Cytopathology
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• v.5 no.2
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• pp.160-166
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• 1994

Collecting duct carcinoma of the kidney is an unusual variety of renal carcinoma considered to arise from the epithelium of the collecting ducts. We recently experienced a case of fine needle aspiration cytology of collecting duct carcinoma of the kidney in a 17 year-old girl. The smear revealed many cellular clusters of ordinary papillary pattern, characterized by clumping of cells with nuclear overlapping, in a slightly necrotic background. The tumor cells had abundant delicate granular cytoplasm with some having vacuolation. The nuclei were only slightly pleomorphic with somewhat coarse chromatin and one or more small nucleoli Some nuclei showed irregular nuclear membrane and nuclear groove. A few polymorphs were also present.