• 한국미생물·생명공학회지
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• 제23권6호
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• pp.730-736
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• 1995

The solubilization and proteolytic process of $\delta $-endotoxin was analvsed to compare the biochemical property of the toxin isolated from B. thuringiensis subsp. sotto. The purified crystals were dissolved in 50 mM carbonate buffer containing 10 mM dithiothreitol at pH 10 for various times. The electrophoretic pattern showed that a rapid disappearance of 138 kDa protein band. This disappearance of protein with high molecular weight was accompanied by the appearance of new protein fragment with 104 kDa, 60 kDa, and 25 kDa. For proteolvtic processing, the soluble crystals were digested with trypsin for various times. The soluble crystal protein of 104 kDa was completely disappeared. However, the protein fragment of 60 kDa and 25 kDa still remained after complete proteolysis. The comparative immunoblot analysis showed that the antiserum against intact crystals showed strong immunoreactivity to the homologous inclusion protein of 138 kDa, 104 kDa, and 25 kDa, and to the intact spores of 221 kDa and 138 kDa, but not to the vegetative cell homogenate. The sera against crystals and spores had no immunoreactivity to the vegetative cell homogenate.

• Fisheries and Aquatic Sciences
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• 제2권1호
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• pp.25-31
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• 1999

Developmental morphology of the red alga, Osmundea crispa (Hollenberg) Nam from California was studied on the basis of liquid-preserved and herbarium specimens. Vegetative axial segment of the species produces two pericentral cells and one trichoblast. Spermatangial filaments (branches) are derived from apical and epidermal cells in pocket-shaped apical pit with an ostiole-like upper opening. Procarp-bearing segment of female trichoblast produces five pericentral cells, of which the fifth functions as supporting cell of carpogonial branch. Tetrasporangial production occurs in random epidermal cells in apical pit of branchlets, and two presporangial cover cells show parallel arrangement to stichidial axis. As this vegetative and reproductive development is included in the generic delineation of Osmundea Stackhouse, O. crispa among the known Osmundea species is characterized by habit forming compact cushion-like clump with angular to terete thallus. It is also distinguished from O. hybrida (AP. de Candolle) Nam without the compressed thallus by the number of pericentral cells in procarp-bearing segment and shape of spermatangial pit. Taxonomic implication of the shape of spermatangial pit is also included.

• Applied Microscopy
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• 제44권2호
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• pp.41-46
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• 2014

In this study, the vegetative and reproductive morphology and anatomy of two Hawaiian endemic Portulaca species were examined. Specifically, P. molokiniensis and P. sclerocarpa were compared to closely related species in the genus. The comparisons were both qualitative and quantitative, using characteristics of leaves, stems, roots, and fruits. Tissue organizations of vegetative and reproductive parts of the plants were assessed using microtechnique procedures, statistical analysis, and scanning electron microscopy. The most notable features of these two species were (1) the size and frequency of stomata in P. molokiniensis, and (2) the large number of sclerenchymatous cell layers in the thickest fruit walls of P. sclerocarpa. These findings may imply that stomata development in P. molokiniensis and thick fruit wall development in P. sclerocarpa are evolved features of survival. In particular, the development of thickened walls in indehiscent fruits likely has evolutionary implications of ecological tolerance for better adaptation.

• Journal of Plant Biology
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• 제5권2호
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• pp.1-5
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• 1962

Attempts were made in order to make clear the meiotic irregularities, male gametophyte formation and spermatogenesis for the purpose of applying these embryological facts to taxonomic works. Followings are the results obtained : 1. Meiosis is extremely irregular, giving rise to giant, micro, and empty, pollens. Meiotic division in each PMC is observed synchronizing. 2. In the microspore immediately before the vegetative-generative nuclear division, the nucleus locates appressed to the inner wall, most of the other part of the cell being occupied by large vacuoles. 3. Spindle symmetry in the microspore nuclear division is of intermediate type. 4. Nuclear divisions in each micropore are not synchronized as in meiosis. 5. Generative nucleus is located in close contact with the inner wall, while the vegetative nucleus occupies the central part of pollen grain. The pollen in this stage looks somewhat like broad bean. Afterward the generative nucleus loses contact with the wall, the nuclear shape changing from lenticular to roundsh. 6. The generative nucleus in fully matured pollen grain usually takes the shape of crescence, those in abortive pollen, lenticular or ellipsoidal, etc.

• Applied Microscopy
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• 제13권1호
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• pp.63-70
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• 1983

The cell division of Bacillus thuringiensis are studed by a electron microscope. It was observed that when the cell division was occurred, the bacterial transverse septeum was centripetally formed, and the bacterial spore was divided into two daughter cells. The fore spore septum was initiated by invagination from either sides of the cell membranes, and was easily distinguished it from the transverse septum of the vegetative cell division. The large vesicular mesosome was. observed at one end of the cell membrane. The nucleoids were of variously irregular shapes and had no a nuclear membrane. The morphology of the bacteria was visualizd by a scanning electron microscope. The surface of the cell was generally rough and had a single polar flagellum, which was appeared to be $0.2{\mu}$ in width and $13{\mu}$ in length.

• The Plant Pathology Journal
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• 제28권3호
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• pp.227-238
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• 2012

Mitogen-activated protein kinase (MAPK) cascades are conserved signaling modules in the eukaryotic cells. They are involved in many major cell processes in fungi such as stress responses, vegetative growth, pathogenicity, secondary metabolism and cell wall integrity. In this review, we summarized the advances of research on the MAPK signaling pathways in Alternaria species. As major phytopathogenic fungi, Alternaria species reduce crop production. In contrast to the five MAPK pathways known in yeast, only three MAPK pathways as Fus3/Kss1-type, Hog1-type, and Slt2-type have been characterized in Alternaria. The Fus3/Kss1-type MAPK pathway participates in regulation of vegetative growth, conidiation, production of some cell-wall-degrading enzymes and pathogenicity. The Hog1-type pathway is involved in osmotic and oxidative stress, fungicides susceptibility and pathogenicity. The Slt2-type MAP kinases play an important role on maintaining cell wall integrity, pathogenicity and conidiation. Although recent advances on the MAPK pathways in Alternaria spp. reveal many important features on the pathogenicity, there are many unsolved problems regarding to the unknown MAP kinase cascade components and network among other major signal transduction. Considering the economic loss induced by Alternaria spp., more researches on the MAPK pathways will need to control the Alternaria diseases.

• Molecules and Cells
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• 제40권10호
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• pp.773-786
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• 2017

The loss of green coloration via chlorophyll (Chl) degradation typically occurs during leaf senescence. To date, many Chl catabolic enzymes have been identified and shown to interact with light harvesting complex II to form a Chl degradation complex in senescing chloroplasts; this complex might metabolically channel phototoxic Chl catabolic intermediates to prevent oxidative damage to cells. The Chl catabolic enzyme 7-hydroxymethyl Chl a reductase (HCAR) converts 7-hydroxymethyl Chl a (7-HMC a) to Chl a. The rice (Oryza sativa) genome contains a single HCAR homolog (OsHCAR), but its exact role remains unknown. Here, we show that an oshcar knockout mutant exhibits persistent green leaves during both dark-induced and natural senescence, and accumulates 7-HMC a and pheophorbide a (Pheo a) in green leaf blades. Interestingly, both rice and Arabidopsis hcar mutants exhibit severe cell death at the vegetative stage; this cell death largely occurs in a light intensity-dependent manner. In addition, 7-HMC a treatment led to the generation of singlet oxygen ($^1O_2$) in Arabidopsis and rice protoplasts in the light. Under herbicide-induced oxidative stress conditions, leaf necrosis was more severe in hcar plants than in wild type, and HCAR-overexpressing plants were more tolerant to reactive oxygen species than wild type. Therefore, in addition to functioning in the conversion of 7-HMC a to Chl a in senescent leaves, HCAR may play a critical role in protecting plants from high light-induced damage by preventing the accumulation of 7-HMC a and Pheo a in developing and mature leaves at the vegetative stage.

• ALGAE
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• 제28권2호
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• pp.161-171
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• 2013

A morphologically distinct lineage within the Bostrychia moritziana-B. radicans species complex is described as a new species. Bostrychia anomala has thalli with branched monosiphonous filaments with apical cell divisions. The species has terminal tetrasporangial stichidia, each subtending cell bearing tetrasporangia with 2 cover cells. Discharged spores divide transversely, the lower cell first forming a narrow rhizoid and the upper cell forming a monosiphonous shoot. Females have subterminal procarps and males have terminal spermatangial stichidia. Carposporophytes are spherical. Isolates in culture show a pattern of cell death not associated with injury, reminiscent of programmed cell death. Bostrychia anomola shows cell death at intervals along the filaments resulting in division of adjacent cells on either side of the dead cell re-joining the filament; cell division of only one adjacent cell resulting in branching at that site; or filaments fragmenting at the cell death point with adjacent cells forming new apical cells, a means of thallus propagation. The cell death pattern could be a method of filament propagation in the mangrove environment where sexual reproduction is rare.

• 한국미생물·생명공학회지
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• 제20권4호
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• pp.470-476
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• 1992

Nocardia mediterranei NCK-4를 동결건조시 생존도에 미치는 영향을 검토하기 위해 보호물질의 종류와 농도, cell 농도 및 건조시간에 대해 실험한 data를 반응표면분석법을 활용하여 분석한 결과, 추정된 최대치의 생존도는 39.3이었으며, 이 최적 조건은 sucrose 11.6(v/v), cell 농도 $1.16{\times}10^{11}$(CFU/ml), 건조 시간 6.18hrs로 나타났다. N.mdeiterranei NCK-4를 동결건조하여 rehydration한 후 계대배양없이 starter cell로서 발효생산에 사용가능성을 검토한 결과, 전배양시 대조군인 FVM(frozen vegetative mycelium)과 거의 비슷하게 cell의 농도를 맞추어 발효함으로써 가능하다. 따라서 이 starter cell은 lyophilization 후 약 18개월간 저장하여 안정하게 사용할 수 있었다.

• Journal of Plant Biology
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• 제27권4호
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• pp.233-239
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• 1984

Reproductives structures of Pachymeniopsis elliptica (Holmes) Yamade (Rhodophyta, Grateloupiaceae) are investigated. In female gametophyte the carpogonial branch and auxiliary cell are produced in separate accessory branch system, the primary ampullar filament originated from mid-cortical layer. After fertilization, auxiliary cell joined with connecting filament becomes a fusion cell by fusing with several neighboring ampullar cells. The fusion cell produces a gonimoblast initial. It divides into gonimoblast cells, which later convert to carposporangia. In male gametophyte superficial cortical cells of vegetative filament produce two spermatangial mother cells which cut off up to three spermatangia respectively. Tetrasporangial initials are formed from the 6th to 12th cells of the cortical layer in tetrasporophyte, and divided cruciately to form tetrasporangium. Some of the sporangia are, however, divided zonately.