• ALGAE
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• v.34 no.1
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• pp.57-70
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• 2019

DNA metabarcoding is currently used for large-scale taxonomic identification to understand the community composition in various marine ecosystems. However, before being widely used in this emerging field, this experimental and analytic approach still has several technical challenges to overcome, such as polymerase chain reaction (PCR) bias, and lack of well-established metabarcoding markers, a task which is difficult but not impossible to achieve. In this study, we present an adapted PCR-free small-organelles enriched metagenomics (SoEM) method for marine biodiversity assessment. To avoid PCR bias and random artefacts, we extracted target DNA sequences without PCR amplification from marine environmental samples enriched with small organelles including mitochondria and plastids because their genome sequences provide a valuable source of molecular markers for phylogenetic analysis. To experimentally enrich small organelles, we performed subcellular fractionation using modified differential centrifugation for marine environmental DNA samples. To validate our SoEM method, two marine environmental samples from the coastal waters were tested the taxonomic capturing capacity against that of traditional DNA metabarcoding method. Results showed that, regardless of taxonomic levels, at least 3-fold greater numbers of taxa were identified in our SoEM method, compared to those identified by the conventional multi-locus DNA metabarcoding method. The SoEM method is thus effective and accurate for identifying taxonomic diversity and presents a useful alternative approach for evaluating biodiversity in the marine environment.

• Plant Resources
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• v.3 no.3
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• pp.163-172
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• 2000

We compared microstructural features of the ordered cell and disordered leaves in Citrus junos Sieb. by electron microscopy. In the cell of the ordered leaves, many chloroplasts and large vacuoles were particularly observed. Also a lot of vessel, companion cell and big nucleus were presented in vascular bundle regions. The mitochondria and the other organelles were interspersed among the chloroplasts in a thin, peripheral layer of cytoplasm. The chloroplast possessed typical grana and intergranal lamellae, numerous starch grains and a few small osmophilic globules. Besides, microbodies were closely associated with the mitochondria and the chloroplast. The process of the formation of the secondary cell wall from primary cell wall was observed the vessel elements, the tonoplast wall and the secondary cell wall. It was observed that the oil sac with the unique perfume distributed the adjacent cell wall. In the cell of disordered leaves, the all of the organelles were thrust toward the cell wall due to the fusion of vacuoles in the cells. It was observed that a lot of the very small particles spreaded in the cytoplasm. The loss of unique perfume of the leaves was resulted in the destruction of the oil sac. Also, there was not observed grana, lamellae, starch and osmophillic globules in the chloroplast. The small distributed organelles was not observed but the elongation of the cell wall was proceed no longer. Therefore, the plasma membrane diverged from the cell wall. All of organelles in the cell had poor function and deformation. A massive vacuole was fulfilled in single cell and the vacuole contains a lot of large and small particles. The organelles were presented on the side of the cell wall according to the enlargement of vacuole and they were observed to be breakdown.

• Korean Journal of Veterinary Research
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• v.39 no.6
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• pp.1057-1065
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• 1999

The study was designated to investigate the electron microscopic findings following diethylnitrosamine (DEN) treatment in rats. Forty four male (Srague Dawley) rats were continuously given water containing 0.01% DEN for 13 weeks and livers of five rats with more tumor lesions at 16 and 17 weeks after initial treatment were used as EM materials. In transmission electron microscopic findings, most small-sized hepatocytes were active cells containing large mount of organelles, but light (pale staining) hepatocytes among small-sized hepatocytes were injured cells containg disorganized organelles. Tumor cells among small-sized hepatocytes were irregularly arranged and have pleomorphic nuclei containing electron dense chromatin but the organelles in cytoplasm were swelled. Large-sized hepatocytes were active cells with condensed chromatin but the cytoplasm of these cells were pale due to be injured and dilated organelles. Dark hepatocytes were apoptotic cells with homogenous pyknotic nuclei and cytoplasm, and the cytoplasm of these cells contained dilated smooth endoplasmic reticulum (sER) but these sER were non-vesiculated. Cholangiocarninoma cells were crowded and were pale by far less number of organelles in cytoplasm and nuclei. In scanning electron microscopic findings, the lumens of portal veins, bile canaliculi, bile ductules, bile ducts and sinusoids were dilated and have irregular folded inner surface by protruded parenchyma.

• Applied Microscopy
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• v.6 no.1
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• pp.1-7
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• 1976

To investigate the nature of typhoid cells, three cases of clinically, serologically and histopathologically proven typhoid lesions of the small intestine and regional lymph nodes were studied light and electron microscopically, Light microscopically, typhoid cells were swollen mononuclear cells characterized by abundant amount of eosinophilic cytoplasm and frequent phagocytoses of red blood cells, bacterial clumps and other tissue debris. These cells were pyronin negative, Electron microscopically, these cells showed marked and diffuse dilatation of RER cisternae and disappearance of ordinary cytoplasmic organelles, but frequent phagocytosed materials, The meaning and reason of RER cisternal dilatation and reduction of cytoplasmic organelles were discussed, and are regarded as degenerative process due to bacterial endotoxin. Although there was hot enough cytoplasmic organelles to pinpoint the origin of typhoid cells, active phagocytosis and evidences against being either plasmacytic or lymphocytic nature favored retuculoendothelial nature of the typhoid cells.

• ALGAE
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• v.34 no.4
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• pp.303-313
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• 2019

Floating seaweed rafts are a surface-pelagic habitat that serve as substrates for benthic flora and fauna. Since 2008, Sargassum horneri clumps have periodically invaded the Korea Strait. In this study, the polymerase chain reaction-free small-organelles enriched metagenomics method was adopted to identify the species of epibiotic eukaryotes present in floating S. horneri fronds. A total of 185 species were identified, of which about 63% were previously undetected or unreported in Korean waters. The rafts harbored a diverse assemblage of eukaryotic species, including 39 Alveolata, 4 Archaeplastida, 95 Opisthokonts, 4 Rhizaria, and 43 Stramenopiles. Of these 185 taxa, 48 species were found at both Sargassum rafts collection stations and included 24 Stramenopiles, 17 Alveolata, and 7 Opisthokonts. Among these, the highest proportion (50%) of species was photo-autotrophic in basic trophic modes, while the proportion of phagotrophic, osmo- or saprotrophic, and parasitic modes were 43.8%, 4.2%, and 2.1%, respectively. This study demonstrates the contribution of floating Sargassum rafts as dispersal vectors that facilitate the spread of alien species.

• Applied Microscopy
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• v.16 no.2
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• pp.49-60
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• 1986

Ultrastructures of the large and elongated cells (idioblasts) in the haustorium of a parasitic angiosperm, Cuscuta australis R. Brown growing on the host plant, Trifolium repens L. were investigated by the electron microscopy. The idioblasts were characterized by the presence of a large nucleus, small vacuoles, and dense cytoplasm including a number of various cell organelles such as ribosome, rough endoplasmic reticulum(r-ER), mitochondrion, dictyosome, proplastid, multilamellar structure(MLS), microfilament bundle(MFB), and cytosegresome. Therefore, it is suggested that the idioblasts are metabolical1y very active. Particularly, MLS, MFB, and cytosegresome observed in this study did not appear in the haustorial cells of the other parasitic angiosperms. MLS was transformed into vacuole and also incorporated with cell wall. MFB composed of microfilaments, about each 7.5 nm in diameter, was observed in nucleus and also cytoplasm. Some types of MFB were distinguished on the basis of arrangement of microfilaments. A part of cytoplasm sequestered by stacked cisternae of smooth ER(s-ER), cytosegresome, was altered into a vacuole which was formed by digestion of the sequestered cytoplasm and of cisternae of s-ER. Cell organelles such as MLS, MFB, and cytosegresome were discussed in relation to the metabolic control of the idioblasts.

• Applied Microscopy
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• v.22 no.1
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• pp.15-32
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• 1992

This study was an attempt to investigate and compare the fine structure of small cells in the space of Disse of various animal livers. All animal livers contained small cells with or without lipid droplets and the one with lipid droplet seemed to be more developed and show an abundance of activity in function. The fine structure of the small cells observed in the nonmammals was similar to that of Ito cell in the mammal. The electron density of the small cells was similar to that of other cell types in the same animal liver. The cisternal dilation of rough endoplasmic reticulum and Golgi apparatus was more predominant in the mammalian Ito cells. In the nonmammalian, aquatic vertebrates, however, lysosomes and filaments are much more abundant in the Ito cell and its abundant cytoplasmic processes rich in filaments were usually extended between the parenchymal cells. The disparity in size of organelles and numbers of lipid droplets in the small cells showed a tendency similar to those of other cell types in the same animal. From these results, it is considered that the small cells in the space of Disse is a Ito cell and the Ito cell without lipid droplets differentiates into the one containing lipid droplets according to the characteristics of the different animals respectively, and that the Ito cells in the mammals are more active in metabolic function, while those in the nonmammalian aquatic vertebrates are abundant in support of parenchyme.

• Applied Microscopy
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• v.15 no.2
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• pp.10-18
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• 1985

The posterior hypothalamus of the hibernating greater horseshoe bats (Rhinolophus ferrumequinum korai Kuroda) were observed with an electron microscope. The posterior hypothalamus is known to be closely related to the reflex responses activated by cold, and the following observations were obtained in the cellular type of nerve cells: there are three types of neurons in the posterior hypothalamus. 1. The first type of neuron was the largest, ovoid or conical in shape, the nucleus was elliptic and the nuclear envelope had many deep invaginations. The cell organelles were well developed, in particular there was an abundance of variously shaped mitochondria, and the Golgi complex and the polysomes were observed in the cytoplasm. 2. The second type of neuron was moderate in size, ovoid or elliptic in shape, the nucleus was located nearer to the plasma membrane and the nuclear envelope had. a few invaginations. The cytoplasm was rich in amount compared with that of the third type of neuron, and the cell organelles, especially the rough endoplasmic reticulum were well developed. Also lipofuscin pigments were observed. 3. The third type of neuron was the smallest in size and round in shape. The nucleus and the nucleolus were observed in the central portion of the cell body and the nuclear envelope had a few invaginations. The cytoplasm was small compared with those of the first and second types, but the rough endoplasmic reticulum, the mitechondria and the polysomes were relatively well developed. The cytoplasm was characterized by the presence of membrane-bound small bodies with a single membrane containing a fine particular substance around the rough endoplasmic reticulum and the Golgi complexes.

• Applied Microscopy
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• v.10 no.1_2
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• pp.1-6
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• 1980

The secretory granul cells in the midgut epithelium of Blattella germanica L. were observed by the electron microscope. These secretory granul cells contain many electron dense granules, and granules are about $200{\AA}$ in diameter respectively. It is easy to distinguish 3 different types of granul cells based on their shapes, location, and staining intensity: 1) The light secretory granul cells and their nucleus are both round form and a number of mitochondria, vacuoles, and other cell organelles appear in the cytoplasm. 2) The other kind of light secretory granul cells are small and oval form but ceil organelles are not well developed in the cytoplasm. This granul cell is surrounded by a few regenerative cells ('nidi'). 3) Dark secretory granul cells are cone shaped, well stained, and endoplasmic reticulum, ribosomes, and a lot of secretory granules are found in the cytoplasm. They are all located in the basal portion of the midgut epithelium.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.27 no.1
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• pp.1-8
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• 2001

This study was designed to localize the distribution of basic fibroblast growth factor(bFGF) in the developing rat condylar region and to elucidate the associated function of bFGF in the condyle development. The condyles of temporomandibular joint of Sprague-Dawley rats (27g of weight) were used. The tissues were examined with electron microscope and immunohistochemical method. The results were as follows: 1. The developing condylar region are divided in to 5 zones apparently: proliferative, maturation, hypertrophic, calcifying, and ossification zones. 2. The cells in the proliferative zone are condensed and have under-developed cell organells in the cytoplasm. This zone shows a strong immunoreactivity of bFGF. 3. The cells in the maturation zone are typical chondroblasts showing well-developed cell organells and round nucleus. The cartilaginous matrix does not show the immunoreactivity of bFGF, while the chondroblasts show the immunoreactivity. 4. The cells in the hypertrophic zone show hypertrophic change having the degenerated cell organelles and small nucleus. There are no immunoreactivity of bFGF in this zone except the nucleus and endoplasmic region showing mild immunoreactivity. 5, The cells in the calcifying zone show hypertrophic change and cell organelles are disappeared. The cells are surrounded by the calcified cartilaginous matrix. There are no immunoreactivity of bFGF in this zone except the endoplasmic region showing mild immunoreactivity. 6. In the zone of bone formation, chondroblasts are disappeared. Newly differentiated osteoblasts secreting osteoid around the calcified cartilaginous matrix. The bone marrow shows the immunoreactivity of bFGF, while the bone matrix does not show the immunoreactivity of bFGF.