• The Korean Journal of Mycology
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• v.22 no.1
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• pp.31-35
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• 1994

Coprinus cinereus resistant strain against validamycin was successfully isolated. Germination rate of oidiospores, branching pattern, and localization of actin protein of the resistant strain were compared with normal strain. The resistant strain showed better germiantion rate of oidia (about 20 fold), more frequent branching, and even actin localization on validamycin plate where actin content was severely reduced in case of normal strain.

• The Plant Pathology Journal
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• v.29 no.1
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• pp.17-30
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• 2013

Barley stripe mosaic virus (BSMV) induces massive actin filament thickening at the infection front of infected Nicotiana benthamiana leaves. To determine the mechanisms leading to actin remodeling, fluorescent protein fusions of the BSMV triple gene block (TGB) proteins were coexpressed in cells with the actin marker DsRed: Talin. TGB ectopic expression experiments revealed that TGB3 is a major elicitor of filament thickening, that TGB2 resulted in formation of intermediate DsRed:Talin filaments, and that TGB1 alone had no obvious effects on actin filament structure. Latrunculin B (LatB) treat-ments retarded BSMV cell-to-cell movement, disrupted actin filament organization, and dramatically decreased the proportion of paired TGB3 foci appearing at the cell wall (CW). BSMV infection of transgenic plants tagged with GFP-KDEL exhibited membrane proliferation and vesicle formation that were especially evident around the nucleus. Similar membrane proliferation occurred in plants expressing TGB2 and/or TGB3, and DsRed: Talin fluorescence in these plants colocalized with the ER vesicles. TGB3 also associated with the Golgi apparatus and overlapped with cortical vesicles appearing at the cell periphery. Brefeldin A treatments disrupted Golgi and also altered vesicles at the CW, but failed to interfere with TGB CW localization. Our results indicate that actin cytoskeleton interactions are important in BSMV cell-to-cell movement and for CW localization of TGB3.

• The Korean Journal of Zoology
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• v.35 no.2
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• pp.149-160
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• 1992

Using the protein A-gold complex, the mvoabrillogenesis and actin localization of cultured myoblast were invastisated. In the superstructural changes of mvogenic cell during differentiation, pectoral myoblasts contained large nucleus and numerous ribosomes but no myofibrils during the first 24 hr of cultures. Mvoblast initiated to differentiate at 3-day of culture contained the primitive myofibrillar structure. At 96 hr of culture, the mvofibrillar structure showed reletively discernable Z band but pools defined A, H and M bands. The feature of sarcomeric structure showed more defined form at cultur 5 day. In the aspect of actin localization, actin wvas diffusely detected throughout the cytoplasm of myogenic cell and nucleus during the proliferating stage. At 72 hr of culture, with the appearantc oi primitive mvofibrils, gold particles were observed in surrounding of myofibrils but still presented in overall of cytoplasm, especially in the surface and lumen of endoplasmic reticulum. With the gradual increase of culture time, local distribution of actin was readily detected within cytoplasm. In the 5-day specimen of cultures, gold particles precisely indicate the sites of actin localifation within the sarcomere. These results indicate the time of onset of myofibrill appearance and the biosynthetic and incorporation pathway of actin molecules into sarcomeric structure during myofibrillogenesis. Thus, in the present study, the first mvoabrillar structure was detected at culture 3 day, and the initiation of assembly into a typical sarcmeric structure was observed at culture 5 day. It seems, however, that the course of events on myofibrillogenesis of cultured myoblasts can be changed with great dependence of culture conditions including the number and groluth rate of mononucleated mvoblasts after seeding although the fundamental process shows identical appearances.

• Applied Microscopy
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• v.30 no.4
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• pp.403-412
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• 2000

Urechis unicinctus spermatogenic cells, sperm and spermatids, prepared from testis are investigated to identify nuclear actin using amoeba monorlonal anti-actin as the first Ab and gold particles (10 nm) conjugated mouse IgG (immunogold) as the Ab marker. The Ag-Ab reactions analyzed the localization of nuclear actin of the spermatogenic cells and the immunogold particles incorporated mainly with nuclear matrices. A few immunogold particles are merged into the acrosomes and the other architectures of spermatogenic cells, such as mitochondrion and centrioles. It is often observed and there is a tendency in which the incorporated immunogold particles are increased in number in the nuclear matrices of sperm compared with that of spermatids The increments and decrements of the incorporated immunogold particles according to developmental stages and the spermatogenic architec-tures are interpreted and discussed in aspect of acrosomal function and of nuclear condensation of spermatids.

• Journal of Microbiology and Biotechnology
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• v.12 no.4
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• pp.628-634
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• 2002

A microfilament-based motility in Toxoplasma gondii (T. gondii) Is involved in host cell invasion, yet the exact mechanism has not yet been determined. Accordingly, the current study examined the localization of actin and tubulin in T gondii using immunofluorescent (IF) and immunogold staining for electron microscopy. Indirect immunofluorescence (IF) staining using anti-actin and anti-tubulin monoclonal antibodies (mAbs) revealed localization of fluorescence on the entire surface of the tachyzoites. The actin in T. gondii was observed by immunogold staining, and the gold particles were seen on the surface, especially at the anterior end and in the cytoplasm of the parasite. However, there were no gold particles in the nucleus, rhoptries, and dense granules. The tubulin in T gondii was located on the surface and in the cytoplasm of the tachyzoites in the extracellular parasite, compared with anterior part of tachyzoites in the intracellular parasite. The antigens of T gondii recognized by anti-actin mAb were 107 kDa, 50 kDa, 48 kDa, and 40 kDa proteins, while those recognized by anti-tubulin mAb were 56 kDa, 52 kDa, and 34 kDa proteins. Tachyzoites of T gondii pretreated with the actin inhibitor, cytochalasin D (20 $\mu\textrm{g}$/ml), and tubulin inhibitor, colchicine (2$\times$10$\^$-6/ M), for 30 min at 37$\^{C}$ were used to infect the isolated mouse macrophages (tachyzo ites:macrophage=2:1). Pretreatment with the inhibitors resulted in lower multiplication of tachyzoites within the macrophages than in the untreated group 18 h post infection (p<0.05). Therefore, the present results suggest that actin and tubulin appear to be involved in the invasion of and multiplication in host cells.

• Molecules and Cells
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• v.37 no.4
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• pp.307-313
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• 2014

Cell migration requires a defined cell polarity which is formed by diverse cytoskeletal components differentially localized to the poles of cells to extracellular signals. Rap-GAP3 transiently and rapidly translocates to the cell cortex in response to chemoattractant stimulation and localizes to the leading edge of migrating cells. Here, we examined localization of truncated RapGAP3 proteins and found that the I/LWEQ domain in the central region of RapGAP3 was sufficient for posterior localization in migrating cells, as opposed to leading-edge localization of full-length Rap-GAP3. All truncated proteins accumulated at the leading edge of migrating cells exhibited clear translocation to the cell cortex in response to stimulation, whereas proteins localized to the posterior in migrating cells displayed no translocation to the cortex. The I/LWEQ domain appears to passively accumulate at the posterior region in migrating cells due to exclusion from the extended front region in response to chemoattractant stimulation rather than actively being localized to the back of cells. Our results suggest that posterior localization of the I/LWEQ domain of RapGAP3 is likely related to F-actin, which has probably different properties compared to newly formed F-actin at the leading edge of migrating cells, at the lateral and posterior regions of the cell.

• Parasites, Hosts and Diseases
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• v.33 no.3
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• pp.155-164
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• 1995

The location of actin and myosin of the several stages of Cwptosporinium parvum was observed. The tissue antigen of C. pcruum was prepared through immunosuppression of IgG mice with Depomedrol . The thin sectioned specimens, which were incubated with the IgG fraction of the rabbit polyclonal antibodies raised against chicken back muscle actin and bovine uterus myosin, were treated with 10 nm gold-conjugated goat anti-rabbit IgG, Electrodense particles were located mainly on the pellicles of all observed developmental stages of the parasites. The number of actin gold particles in the cytoplasm increased when the parasite was dividing actively as in case of meronts. Especially in macrogametocytes, a lot of actin and myosin particles were synthesized and storaged as amilopectin-like bodies. There were many actin gold particles along the microspikes of cytoplasmic membranes in various developmental stages. The actin and myosin observed in this study may play important roles to control the shape of the parasites and movement of cytoplasmic membranes as cvtoskeletal proteins.

• Parasites, Hosts and Diseases
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• v.34 no.4
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• pp.215-224
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• 1996

actin and some actin binding proteins such as tropomyosin, α-actinin and troponin T were localized by simultaneous double immunogold labeling in several developmental stages of Cryptosporidium parvum. All of the observed developmental stages have many paricles of tropomyosin and actin around pellicle and cytoplasm. Tropomyosin was labeled much more than the actin when these two proteins were labeled simultaneously. And α-actinin was labeled mostly in the pellicle, but troponin T labeling weas very rarely observed. From this study it was suggested that tropomyosin seemed to be one of the major proteins of C. parvum, so it must be playing important roles in C. parvum.

• Reproductive and Developmental Biology
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• v.37 no.4
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• pp.169-174
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• 2013

Sperm capacitation refers to polymerization of filamentous (F)-actin from globular (G)-actin. While the role of actin-related protein 2/3 (Arp2/3) complex in actin polymerization is well appreciated, the underlying mechanism(s) and its relationship with capacitation are poorly understood. Therefore, to evaluate the potential role of Arp2/3 complex on capacitation, bovine spermatozoa were incubated with multiple doses (1, 10 and $100{\mu}M$) of CK-636, an inhibitor of Arp2/3 complex with heparin. The cellular localization of the Arp2/3 complex in spermatozoa was identified by immunohistochemistry, whereas western blot was also applied to detect the protein tyrosine phosphorylation of sperm proteins. Additionally, sperm motility and kinematic parameters were evaluated using a computer-assisted sperm analysis system. CK-636 resulted in significant changes in the ratio of Arp2/3 complex localization between acrosome and equatorial region of the spermatozoa. Short-term exposure of spermatozoa to $100{\mu}M$ of CK-636 significantly decreased sperm motility, however a non-detectable effect on protein tyrosine phosphorylation was observed during capacitation. On the basis of these results, we propose that Arp2/3 complex is associated with morphological changes during capacitation and compromised sperm motility.

• Animal cells and systems
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• v.1 no.1
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• pp.93-98
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• 1997

The present study investigated the cellular localization of a-subunit of Gq (Gaq) protein in developing L8E63, rat skeletal muscle cell line. The colocalization of Gaq with actin cytoskeleton was demonstrated by double-labeling experiments. In mononucleated myoblasts, the immuno-fluorescence staining pattern of Gaq was almost identical with that of F-actin visualized with rhodamine-conjugated phalloidin. However, this colocalization of Gaq with cytoskeleton was not maintained in multinucleated myotubes. The staining pattern of Gaq in myotubes did not match with any specific subcellular structure, but appeared as a uniformly distributed diffuse staining throughout the whole cell surface. Interestingly, change in the expression level of Gaq was not detected during myoblast differentiation, suggesting that actin-associated Gaq protein might dissociate from the cytoskeleton as cells differentiate. Immunocytochemical experiments using specific antibodies directed against several G proteins indicated that the subcellular localizations of Gai1, Gai2, Gai3, and Gao were different from those obtained with Gaq.