• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.2
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• pp.157-162
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• 2003

Ultrastructure of germ cell during gametogenesis of surf clam, Spisula sachalinensis were investigated by electron microscopic observations. Oogonia are oval in shape and 5-6 ${\mu}m$ in diameter. They contain a large nucleus and have several mitochondria in the cytoplasm. Vitellogenic oocytes grew attached by a stalk to the germinal epithelium in the ovarian sac and their cytoplasm contained many yolk granules, lipid granules and mitochondria. Mature oocytes measuring 50-60 ${\mu}m$ in diameter have a nucleus containing an electron dense nucleolus, and a lots of yolk granules, lipid granules, mitochondria, rough endoplasmic reticulum and cortical granules were present in the cytoplasm. The surface of the plasma membrane in mature oocytes was formed of microvilli approximately 1.5 ${\mu}m$ long and enveloped in the vitelline layer. Spematogonia are oval in shape and about 5 ${\mu}m$ in diameter. Sprmatogonia develop into spermatocyte, spermatid and spermatozoon. The spermatozoon consisted of the head, midpiece and tail. The sperm head with diameter of about 1.5 ${\mu}m$ was ovoid, and contained the nucleus which consisted of acrosome. The four mitochondria encircled the centrosome in midpiece. The flagellum measuring about 40 ${\mu}m$ long had the classical 9+2 axoneme structure.

• Applied Microscopy
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• v.24 no.2
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• pp.93-104
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• 1994

Six types of hemocytes were identified in adult grasshopper, Euprepocnemis shirakii Bolivar. The morphological and ultrastructural characteristics of these cells were characterized by phase contrast, scanning and transmission electron microscope. The prohemocytes are small and spherical cells with large nucleus. The plasmatocytes are spindle shaped or polymorphic cells which show numerous cytoplasmic processes on the cell surface and they have lysosomes and vesicles that may be involved in phagocytic function. Especially, multivesicular bodies are observed in the polymorphic cells. The granulocytes I are spherical shaped cells. They are characterized by a number of electron dense granules measuring $0.2-0.3{\mu}m$ in average diameter and marginal band of microtubules which are always in close proximity to the cell membrane. The granulocytes II are oval or spindle-shaped cells. They contain large electron dense granules measuring $0.5-0.8{\mu}m$ in average diameter. Their cytoplasm is filled with numerous granules. The spherulocytes contain large amounts of spherules that most of their cytoplasm. Spherules filled with fine granules or flocculent materials. The oenocytoids are large spherical cells with few cytoplasmic organelles. Their cytoplasm contains peculiar aspect of motochondria and numerous polyrobosome.

• Journal of Plant Biology
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• v.36 no.3
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• pp.285-292
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• 1993

Cellular compatibility in the self-parasitism of Cuscuta australis R. Brown was studied at the ultrastructural level. The front cells of the haustorium penetrated the host stems independently grew within the host tissues and transformed into elongate, filamentous hyphae. Each hyphal cells contained a large nucleus and dense cytoplasm with abundant cell organelles. Multilamellar structures were contained in the cytoplasm and cell walls of the penetrating hyphal cells. When the hyphal cells did not yet invade the host cells, the middle lamella and the fused cellulosic cell walls of the two partners at the host-parasite interface were preserved well. As the invasion of the parasitic hyphal cells progressed, however, the middle lamella was not found at the interface and the host cell walls and plasma membranes were partially broken down. A hyphal cell penetrated deeply into the host cell had a more darkly stained cytoplasm with numerous of cell organelles. In the host cells attacked by the hyphal cells the limiting membranes of plastids were broken down and several vesicles were arrayed near the cell walls. No plasmodesmatal connections between the host and parasite cell walls were found; however, half-plasmodesmata were observed frequently on the side of the hyphal cell walls. These results suggested that the compatibility response in the self-parasitism of Cuscuta was expressed by cell walls, not by plasmodesmata, between the host and the parasite cells.

• The Korean Journal of Zoology
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• v.35 no.2
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• pp.161-172
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• 1992

In the short-term treahent of 12-0-tetradecanoylphorbol-13-acetate (TPA) or platelet-derived growth factor (PDGF), the'Wh and PDGF induced the Protein Kinase C (PKC) activation and migration from the cytoplasm to the peripheral nulcear membrane. And the activated PKC which was directly or indirectly stimulated by TPA or PDGF Phosphorylated many kinds of PKC's targeting proteins and induces various biological responses. Especially, the cytoplasmic PKC was phosphorylated within 1 hr and 10 min by TPA-and PDGF-treahent respectivelv. In the long-term treatment of TPA or PDGF, both of them induced the down-regulation and translocation of PKC in the mvoblasts. The down-regulation of PKC isozyrnes, the pattern of PKC I and ll was similar to the PKC 111 isozpnes in the cytoplasm. But in the nucleolus, the TPA did not induce and down-regulation or the inhibition of the immunoreactivity of PKC III antibody. This investigation indicates that each isozvmes of PKC mal be performed the different effects to the down-regulation of the cytoplasm or nucleolus. And douvn-regulated myoblasts contained low immunoreactivity of PKC antibodies.

• BMB Reports
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• v.50 no.5
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• pp.257-262
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• 2017

The subcellular localization of Bax plays a crucial role during apoptosis. In response to apoptotic stimuli, Bax translocates from the cytoplasm to the mitochondria, where it promotes the release of cytochrome c to the cytoplasm. In cells infected with HSV-1, apoptosis is triggered or blocked by diverse mechanisms. In this study, we demonstrate how HSV-1 ICP27 induces apoptosis and modulates mitochondrial membrane potential in HEK 293T cells. We found that ICP27 interacts with $14-3-3{\theta}$ which sequesters Bax to the cytoplasm. In addition, ICP27 promotes the translocation of Bax to the mitochondria by inhibiting the interaction between $14-3-3{\theta}$ and Bax. Our findings may provide a novel apoptotic regulatory pathway induced by ICP27 during HSV-1 infection.

• Animal cells and systems
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• v.14 no.4
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• pp.343-349
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• 2010

Ultrastructural studies of vitellogenesis in oocytes and follicle cells during oogenesis in female Protothaca (Notochione) jedoensis were investigated by histological and transmission electron microscope observations. In early vitellogenic oocytes, combined activities of the Golgi complex, mitochondria and rough endoplasmic reticulum in the cytoplasm are associated with autosynthetic vitellogenesis. Furthermore, at this time, many coated vesicles at the basal region of the oolemma of the oocyte lead to the formation of vesicles through endocytosis in the cytoplasm. Through the formation of the coated pits on oolemma during vitellogenesis, the uptake of extrafollicular precursors (nutritive materials) occurs in coated vesicles by endocytosis. Therefore, it is assumed that these exogenous materials are involved in heterosynthetic vitellogenesis. During late oogenesis, exogenous yolk precursors (yolk granules), lipid droplets and proteinaceous yolk granules are present in the cytoplasm of late vitellogenic oocytes. In mature oocytes, small yolk granules appear intermingled and form large mature yolk granules. Thus, two processes of vitellogenesis occur in oocytes by way of endogenous autosynthesis and exogenous heterosynthesis. The follicle cells attached to the oocytes appear to play an integral role in vitellogenesis in this study.

• The Plant Pathology Journal
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• v.27 no.1
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• pp.8-13
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• 2011

The induced resistance of cucumber leaves treated with oligochitosan to the infection of the cucumber powdery mildew, Sphaerotheca fuliginea, was investigated using transmission electron microscopy. The results showed that when the plants were treated with oligochitosan and challenged with inoculum, a significant decrease of the disease occurred. The mycelial development in the treated leaves was markedly inhibited. The cytoplasm of the powdery mildew mycelium was aggregated, with its organelles disintegrated and the cytoplasm collapsed. The protoplasm in haustoria became electron-dense. Haustoria became malformed, their organelles disintegrated, the hausterial wall thickened and eventually the whole complex necrotized. The host cells produced defence structures and materials associated with infection and a hypersensitive response. The host cell wall was thickened and deeply stained; several layers of papilla structure were produced under the cell wall; dark materials were deposited between the cell wall and plasmalemma; extrahaustorial plasmalemma was deeply stained and extrahaustorial matrix appositions had large deposits of electron-dense material; the cytoplasm was disordered, host organelles disintegrated and eventually the whole host cell disintegrated and necrotized.

• Korean Journal of Microbiology
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• v.41 no.4
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• pp.312-315
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• 2005

Coprinellus congregatus, known as an inky cap, is autolysed into ink soon after the maturation of the mushrooms. Electron microscopy was used to examine the ultrastructural changes associated with the autolysis as an initial step to understand the role of hydrolytic enzymes in this process. During the early stages of maturation of the mushrooms, most of cytoplasm of hymenial and subhymenial tissues seemed to be transported to the developing basidiospores. The depletion of cytoplasm within the tissues and the maturation of the basidiospores may initiate the degradation of the cell walls of the tissues. Both hymenial and subhymenial tissues seemed to degraded at the same time. This study suggested that the critical steps in the autolysis of mushrooms is not the degradation of the cytoplasm, but the degradation of the cell wall by hydrolytic enzymes such as chitinases.

• Parasites, Hosts and Diseases
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• v.31 no.4
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• pp.315-320
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• 1993

We observed ultra-structure of the tribocytic organ of Firicola seoulensis with transmission electron microscope. Microvilli are observed on the surface of the tribocytic organ. Below the muscle layer, we can find three types of cells. Type I cell has electron lucent cytoplasm with a few granules, while type II cell shows electron dense cytoplasm and the particulate granules. Type III cell's electron dense cytoplasm possesses many granules. Of the above three cells, Type I and II cells are believed as tegumental cells. Type III cells are thought as glandular cells specific to the tribocytic organ. This finding on also explain the secretory function of the tribocytic organ of f seoulensis.

• BMB Reports
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• v.56 no.9
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• pp.514-519
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• 2023

Methyltransferase-like 3 (METTL3), a key component of the m⁶A methyltransferase complex, regulates the splicing, nuclear transport, stability, and translation of its target genes. However, the mechanism underlying the regulation of METTL3 expression by alternative splicing (AS) remains unknown. We analyzed the expression pattern of METTL3 after AS in human tissues and confirmed the expression of an isoform retaining introns 8 and 9 (METTL3-IR). We confirmed the different intracellular localizations of METTL3-IR and METTL3 proteins using immunofluorescence microscopy. Furthermore, the endogenous expression of METTL3-IR at the protein level was different from that at the mRNA level. We found that 3'-UTR generation by intron retention (IR) inhibited the export of METTL3-IR mRNA to the cytoplasm, which in turn suppressed protein expression. To the best of our knowledge, this is the first study to confirm the regulation of METTL3 gene expression by AS, providing evidence that the suppression of METTL3 protein expression by IR is an integral part of the mechanism by which 3'-UTR generation regulates protein expression via inhibition of RNA export to the cytoplasm.