• 대한바이러스학회지
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• 제27권1호
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• pp.29-37
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• 1997

To use recombinant viruses with wider host range as viral insecticides, we investigated the characteristics and pathogenicity of host range expanded recombinant viruses in insect cells. We compared host range expanded recombinant viruses, RecS-B6 and RecB-8, constructed by cotransfection of Autographa californica nuclear polyhedrosis virus (AcNPV) and Bombyx mori NPV (BmNPV), to host range expanded AcNPV, Ac-BH, by substitution of the 0.6 Kb fragment of the BmNPV helicase gene. Restriction endonuclease profiles of RecS-B6 and RecB-8 DNAs were different from those of parent viruses. Nucleotide sequence analysis of the 0.6 Kb region in the putative helicase gene of RecS-B6 and RecB-8 showed that their structures were identical to the counterpart region of BmNPV. Comparison of viral replication of these recombinant viruses in Sf-21 and BmN-4 cells showed that Ac-BH, compared to wild type viruses, replicated well in BmN-4 cells but poorly in Sf-21 cells. In contrast, RecS-B6 and RecB-8 replicated relatively well in both cells compared to parent viruses. These results may imply that random genomic recombinant viruses, RecS-B6 and RecB-8, possess better potential as viral pesticides than helicase-mediated recombinant virus, Ac-BH.

• Genomics & Informatics
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• 제3권3호
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• pp.63-67
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• 2005

Adaptive responses to diverse microbial pathogens might be limited in relatively few types. Host cell responses to pathogens are believed to be patterned or stereotyped along with species or class. We tried to compose the host response to Mycoplasma in terms of cellular gene expression. Although gene expression profile of two host HeLa and 293 cells were quite different each other, 30 genes were differentially expressed by mycoplasma infection in both of HeLa and 293 cells. Six of them (PR48, MADH4, MKPX, CRK, RBM7, NEK3) were related to cell cycle or proliferation. Another category of genes like IL1 HY1, KLRF1, TNFSF14, GBP1 were host defense to elicit immune responses. With this set of genes, we establish the prediction model for mycoplasma contamination.

• The Plant Pathology Journal
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• 제31권3호
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• pp.299-304
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• 2015

Interaction of the the rust fungus Puccinia miscanthi with the biofuel plant Miscanthus sinensis during the teliospore phase was investigated by light and electron microscopy. P. miscanthi telia were oval-shaped and present on both the adaxial and abaxial leaf surfaces. Teliospores were brown, one-septate (two-celled), and had pedicels attached to one end. Transmission electron microscopy revealed numerous electron-translucent lipid globules in the cytoplasm of teliospores. Extensive cell wall dissolution around hyphae was not observed in the host tissues beneath the telia. Hyphae were found between mesophyll cells in the leaf tissues as well as in host cells. Intracellular hyphae, possibly haustoria, possessed electron-dense fungal cell walls encased by an electron-transparent fibrillar extrahaustorial sheath that had an electron-dense extrahaustorial membrane. The infected host cells appeared to maintain their membrane-bound structures such as nuclei and chloroplasts. These results suggest that the rust fungus maintains its biotrophic phase with most mesophyll cells of M. sinensis. Such a nutritional mode would permit the rust fungus to obtain food reserves for transient growth in the course of host alteration.

• ALGAE
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• 제20권4호
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• pp.363-368
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• 2005

The brown alga Ascophyllum nodosum and its mutualistic, ascomycete symbiont, Mycophycias ascophylli, form a complex ‘rganism’or symbiotum. Here we show the interaction of the symbiotum to the abundant brown algal epiphyte, Elachista fucicola. Microscopy of field-collected plants shows morphological responses of A. nodosum to the common epiphyte E. fucicola. When E. fucicola attaches to A. nodosum a bundle of several to dozens of rhizoids penetrates into the host. On the surface of the host, the cells proliferate to form a donut-shaped ring, 100-200 μm in height that surrounds the thallus of E. fucicola. A pit forms in advance of the rhizoids and the cells of A. nodosum break down. This leaves the network of fungal hyphae partially intact and intermingling with the epiphyte rhizoids and its lowermost cells. After the pit is formed, the cells of A. nodosum bordering the infection chamber redifferentiate an epidermal layer. Neither the host nor its mutualistic fungus, M. ascophylli appears to recognize E. fucicola as an invader and to prevent the attachment and growth of this epiphyte. Based on the physical damage to the host caused by invading rhizoids, we conclude that the relationship of E. fucicola to A. nodosum is that of a parasite and its host.

• 한국작물학회지
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• 제49권4호
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• pp.316-324
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• 2004

Sinorhizobium sp. strain MUS10 forms nitrogen-fixing stem nodules on Sesbania rostrata, a tropical green manure crop. In this study, the ultrastructural events associated with the formation of stem nodules were investigated. Sinorhizobium sp. strain MUS10 entered the host tissue through cracks created by the emerging adventitious root primordia and multiplied within the intercellular spaces. During early phases of infection, host cells adjacent to invading bacteria revealed cellular damage that is typical of hypersensitive reactions, while the cells at the inner cortex exhibited meristematic activity. Infection threads were numerous in S-day-old nodules and often were associated with the host cell wall. In several cases, more than one infection thread was found in individual cells. The junction at which the host cell walls converged was often enlarged due to fusion of intracellular branches of infection threads resulting in large infection pockets. The infection threads were made up of a homogeneous, amorphous matrix that enclosed the bacteria. Several finger-like projections were seen radiating from these enlarged infection threads and were delineated from the host cytoplasm by the plasma membrane. As in Azorhizobium caulinodans induced root nodules, the release of Sinorhizobia from the infection threads into the plant cells appears to be mediated by 'infection droplets'. A 15-day­old Sesbania stem nodule revealed typical ultrastructure features of a determinate nodule, containing several bacterioids within symbiosomes.

• Applied Microscopy
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• 제17권1호
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• pp.161-168
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• 1987

The elongated filamentous haustorial cells, hyphae, of Cuscuta australis R. Brown penetrated into the vascular tissues of the host plant Trifolium repens L. were studied by the light and electron microscopes. The hyphae reached the host xylem were invaded into the host vessels and then they grew within the host vessels. Finally these hyphae were differentiated into the water conducting elements, xylary hyphae, by thickening of the secondary walls. The hyphae reached the host phloem were branched at the apical regions. These hyphae possessed thin-layered cytoplasm involving the typical features of sieve elements such as the parallel arrays of smooth endoplasmic reticulum, plastids with the clusters of fine starch granules, and mitochondria with the dilated cristae. It was indicated that these hyphae were differentiated into the nutrients conducting elements, phloic hyphae. The structures described were compared with those of other parasitic plants and were discussed in view of the translocation of materials from host to parasite.

• Biotechnology and Bioprocess Engineering:BBE
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• 제5권2호
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• pp.84-91
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• 2000

Mycopasma contamination of tissue culture cells easily evades detection and, thus, represents a continous therat to cell biologists. In case where infected cell can not simply be replaced, attempts have to be made to eradicate mycoplacma from the tissue culture cells. A variety of anti-microbial agents have been shown to be toxic to mycoplasma strains ; however, cell associated mycoplasma are often protected from antibiotics at concentrations shown to be effective in vitro. Antibiotic concentrations high enough to be lethal to cell as sociated mycoplasmas frequently are also detrimentrations to the host cells, while moderately increased antibiotic levels tolerated by the host cells often lead to only temporary growth suppression and/or to the emergence of mycoplasma strains resistanct even to high concentrations of the antibiotis applied. Hare, a genetic approach for the elimination of mycoplasma from tissue culture cells that overcomes thens limitations is described. By expression of a selection marker conferring resistance to an otherwise toxic agent, Acholeplasma laidlawii infected BHK-21 cells used as the model system were enabled to temporarily tolerate antibiotic concentrations high enough to be lethal to cell associated mycopalsma while leaving the host cells unharmed. Upon successful mycoplasma eradicated, cultvation of the cured host cells in the absence of the selective agent yielded revertant cell clones that had regained susceptibillity to the toxic agent. Cressation of the selection marker expression was shown to result from the loss of the selection marker DNA, which is a consequence of the fact that the stable and permanent integration of foreign DNA in eucaryotic cell chrosomes is highly inefficient. Thus, the cells were cured from mycoplasma yet remained biochemically unaltered.

• IMMUNE NETWORK
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• 제11권6호
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• pp.428-430
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• 2011

We previously demonstrated that in vivo engagement of CD137, a member of TNF receptor superfamily, can delete allorective $CD4^+$ T cells through the induction of activation-induced cell death (AICD) in chronic graft-versus-host disease (cGVHD) and subsequently reverse established cGVHD. In this study, we further showed that agonistic anti-CD137 mAb was highly effective in triggering AICD of donor $CD8^+$ T cells as well as donor $CD4^+$ T cells in the $C57BL/6{\rightarrow}unirradiated$ $(C57BL/6\;{\times}\;DBA/2)F1$ acute GVHD model. Our results suggest that strong allostimulation should facilitate AICD of both alloreactive $CD4^+$ and $CD8^+$ T cells induced by CD137 stimulation. Therefore, depletion of pathogenic T cells using agonistic anti-CD137 mAb combined with potent TCR stimulation may be used to block autoimmune or inflammatory diseases mediated by T cells.

• Molecules and Cells
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• 제41권1호
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• pp.27-34
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• 2018

The cytoplasm in mammalian cells is a battlefield between the host and invading microbes. Both the living organisms have evolved unique strategies for their survival. The host utilizes a specialized autophagy system, xenophagy, for the clearance of invading pathogens, whereas bacteria secrete proteins to defend and escape from the host xenophagy. Several molecules have been identified and their structural investigation has enabled the comprehension of these mechanisms at the molecular level. In this review, we focus on one example of host autophagy and the other of bacterial defense: the autophagy receptor, NDP52, in conjunction with the sugar receptor, galectin-8, plays a critical role in targeting the autophagy machinery against Salmonella; and the cysteine protease, RavZ secreted by Legionella pneumophila cleaves the LC3-PE on the phagophore membrane. The structure-function relationships of these two examples and the directions of future research will be discussed.

• BMB Reports
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• 제55권12호
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• pp.587-594
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• 2022

A persistent DNA tumor virus infection transforms normal cells into cancer cells by either integrating its genome into host chromosomes or retaining it as an extrachromosomal entity called episome. Viruses have evolved mechanisms for attaching episomes to infected host cell chromatin to efficiently segregate the viral genome during mitosis. It has been reported that viral episome can affect the gene expression of the host chromosomes through interactions between viral episomes and epigenetic regulatory host factors. This mini review summarizes our current knowledge of the tethering sites of viral episomes, such as EBV, KSHV, and HBV, on host chromosomes analyzed by three-dimensional genomic tools.