• Journal of Ecology and Environment
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• 제32권3호
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• pp.207-215
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• 2009

Greenbelts were designated by the Korean government in 1971 in 14 large cities to prevent uncontrolled urban expansion. Recently, deregulation of the greenbelt system has resulted in further development, but the ecological role of greenbelts has not been fully considered when decisions about urban management are being made. We examined the ecological roles of the greenbelt system in the Seoul metropolitan area and prepared sustainable management and improvement plans based on our analysis of landscape characteristics using satellite images covering a ${\sim}30$-year period. The loss of forest cover during this period in the greenbelt areas was lower than that in the areas outside and inside of the greenbelt. Fragmentation of forest cover was correlated with the pattern of loss of forest cover. The NDVI of the greenbelt remained steady at 90% of that in outside of the GB for three decades. This suggests that the greenbelt system has performed its primary roles well. However, the remaining green space was not adequate to provide a sink for air pollutants even when the greenbelt area was included. We discuss how the negative effects of urbanization can be reduced through sustainable management and restoration to promote ecological functioning in greenbelts and urban landscapes.

• BMB Reports
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• 제42권12호
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• pp.769-775
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• 2009

Periplasmic glucans (PGs) are general constituents in the periplasmic space of Proteobacteria. PGs from bacterial strains are found in larger amounts during growth on medium with low osmolarity and thus are often been specified as osmoregulated periplasmic glucans (OPGs). Furthermore, they appear to play crucial roles in pathogenesis and symbiosis. PGs have been classified into four families based on the structural features of their backbones, and they can be modified by a variety of non-sugar substituents. It has also recently been confirmed that novel PGs with various degrees of polymerization (DPs) and/or different substituents are produced under different growth conditions among Proteobacteria. In addition to their biological functions as regulators of low osmolarity, PGs have a variety of physico-chemical properties due to their inherent three-dimensional structures, hydrogen-bonding and complex-forming abilities. Thus, much attention has recently been focused on their physico-chemical applications. In this review, we provide an updated classification of PGs, as well as a description of the occurrences of novel PGs with substituents under various bacterial growth environments, the genes involved in PG biosynthesis and the various physico-chemical properties of PGs.

• Applied Microscopy
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• 제43권1호
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• pp.14-20
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• 2013

The leopard danio, Danio rerio var. frankei is a spotted color morph of the zebrafish, Danio rerio caused by a pigment mutation. The structural differences of fertilized egg and egg envelope are poorly documented. To clarify this, we compared the fertilized egg morphology and ultrastructures of surface structures, the micropyle and the cross section of fertilized egg envelopes of zebrafish and leopard danio, variation species of zebrafish using a light and electron microscopes. Although the fertilized egg sizes were different, the external shapes of the fertilized eggs of two species couldn't be differentiated under the light microscope. The characteristics of fertilized eggs, such as a spherical shape, a non-adhesive quality and a large perivitelline space, were shown to be related to spawning habit. In ultrastructure of fertilized egg envelope, there is no morphological difference of micropyle between two species. By contrast, the ultrastructure and the numbers of knob-like structures and semihemisphere-like structures per unit area on the outer surface, and the number of lamellae of inner layer on the fertilized egg envelope section displayed definite species specificity. Collectively, our data indicate that the ultrastructure of fertilized egg envelope in the zebrafish could be differentiated by species variation.

• Molecules and Cells
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• 제23권1호
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• pp.1-10
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• 2007

Invading pathogens are recognized by diverse germline-encoded pattern-recognition receptors (PRRs) which are distributed in three different cellular compartments: extracellular, membrane, and cytoplasmic. In mammals, the major extracellular PRRs such as complements may first encounter the invading pathogens and opsonize them for clearance by phagocytosis which is mediated by membrane-associated phagocytic receptors including complement receptors. The major membrane-associated PRRs, Toll-like receptors, recognize diverse pathogens and generate inflammatory signals to coordinate innate immune responses and shape adaptive immune responses. Furthemore, certain membrane-associated PRRs such as Dectin-1 can mediate phagocytosis and also induce inflammatory response. When these more forefront detection systems are avoided by the pathogens, cytoplasmic PRRs may play major roles. Cytoplasmic caspase-recruiting domain (CARD) helicases such as retinoic acid-inducible protein I (RIG-I)/melanoma differentiation-associated gene 5 (MDA5), mediate antiviral immunity by inducing the production of type I interferons. Certain members of nucleotide-binding oligomerization domain (NOD)-like receptors such as NALP3 present in the cytosol form inflammasomes to induce inflammatory responses upon ligand recognition. Thus, diverse families of PRRs coordinately mediate immune responses against diverse types of pathogens.

• Parasites, Hosts and Diseases
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• 제43권4호
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• pp.141-147
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• 2005

A practical and convenient method of rearing Eucyclops serrulatus in a microculture environment is described. A complete life cycle of E. serrulatus was maintained in a narrow space on a microscope slide glass on which a cover glass of $22{\times}40mm$ in size was mounted at a height of 0.8mm. The culture medium was constituted by bottled mineral water boiled with grains of Glycine max (soybean). Chilomonas paramecium, a free-living protozoan organism, was provided as live food. Growth of nauplii hatched from eggs to the first stage of copepodite took an average of 7.7 days, and the growth of copepodite 1 to the egg-bearing adult female took an average of 20.1 days in the microculture cell with an average life time of 44.7 days. Continuous passage of cope pods was successfully maintained as long as sufficient medium and food were provided. The microculture method enables an in situ microscopic observation on the growth and developmental process of helminth larvae experimentally infected to copepods as well as of copepod itself. Furthermore, it does not require anesthetization and, therefore, minimize the amount of stress exposed to cope pods during the handling process.

• International Journal of Industrial Entomology and Biomaterials
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• 제6권2호
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• pp.115-123
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• 2003

Oviposition and egg laying is an important physiological and behavioural event in the life cycle of the silkworm, Bombyx mori (L). Oviposition and egg laying is dependent on a number of intrinsic and extrinsic factors viz., neural, hormonal, environmental, physical, behavioral etc for the perpetuation of population. Although, the virgin female moths have fully developed embryos but active egg laying begins under the influence of mating which provides essential copulation stimulus for oviposition. After mating drastic biochemical changes occurred that incites egg laying under the influence of optimum environmental conditions. Weight of pupae as well as larval density has significant role on oviposition and egg laying behaviour in the silkworm wherein high pupal weight and inadequate rearing space affects not only the biology, morphology and physiology but also the oviposition and egg laying. Surface topography, plane of inclination, mating length, age of male moth, temperature and photoperiod etc has significant effect on reproductive physiology of silkworm. An attempt has been made in this review article to elucidate briefly the works carried out on mating behaviour, direct and indirect copulation stimulus, vitellogenesis, influence of environmental factors besides effect of weight of pupae and or pharate adult and larval density on oviposition and egg laying behavior in the silkworm, B. mori and its significance in silkworm seed production.

• Journal of Ecology and Environment
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• 제30권1호
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• pp.75-80
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• 2007

This study evaluated the effects of rehabilitation of existing coal mining spoils on species composition and species diversity. The species composition of most rehabilitated stands differed from that of the reference stands, and thus did not suggest successful rehabilitation. However, stands subjected to restorative treatment many years ago showed higher species diversity than the reference stands and thereby met the goals of rehabilitation. Our results demonstrate that restorative treatments practiced in the past created a heterogeneous ecological space with regard to the surrounding areas. Therefore, even though species diversity increased several years after rehabilitation, this does not indicate that the treatment achieved true rehabilitation success. The treatment did result in temporary stability through increased species diversity, but it could not be described as successful rehabilitation in terms of biological integrity with the surrounding ecosystems.

• BMB Reports
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• 제29권1호
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• pp.38-44
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• 1996

Taq DNA polymerase from Thermus aquaticus has been shown to be very useful in the polymerase chain reaction method, which is being used for amplifying DNA. Not only does Taq DNA polymerase have high commercial value commercial value for the polymerase chain reaction application, but it is also important in studying DNA replication, because it is apparently an homologue to E. coli DNA polymerase I, which has long been used for DNA replication study (Lawyer et ai., 1993). The crystal structure determination of Taq DNA polymerase was initiated. An X-ray diffraction pattern breaks down a crystal structure into discrete sine waves in a Fourier series. The original shape of a crystal object in terms of electron density may be represented as the sum of those sine waves with varying amplitudes and phases in three dimensions. The molecular replacement method was initially employed to provide phase information for the structure of Taq DNA polymerase. The rotation search using the program MERLOT resulted in a solution peak with 5.4 r.m.s. PC-refinement of the X-PLOR program verified the result and also optimized the orientation angles. Next, the translation search using the X-PLOR program resulted in a unique solution peak with 7.35 r.m.s. In addition, the translation search indicated $P3_121$ to be the true space group out of two possible ones. The phase information from the molecular replacement was useful in the MIR phasing experiment.

• BMB Reports
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• 제31권6호
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• pp.600-603
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• 1998

A highly thermostable xylose isomerase from Thermus thermophilus has been expressed in Escherichia coli and crystallized. The purified enzyme shows its optimum temperature at $90^{\circ}C$. It has been crystallized at room temperature using polyethylene glycol 4000 as the precipitant. The crystal belongs to the orthorhombic space group $P2_12_12_1$, with unit cell parameters of a = 73.34 ${\AA}$, b = 144.05 ${\AA}$, c = 155.07 ${\AA}$. The presence of one molecule of tetrameric xylose isomerase in the asymmetric unit gives a crystal volume per protein mass ($V_m$) of 2.32 ${\AA}^3/Da$ and the solvent content of 47.0% by volume. The diffraction pattern extends to 1.9 ${\AA}$ Bragg spacing with synchrotron radiation and a set of native data has been collected to 2.3 ${\AA}$.

• BMB Reports
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• 제39권6호
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• pp.717-721
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• 2006

In vitro analyses of type I signal peptidase activities require protein precursors as substrates. Usually, these pre-proteins are expressed in vitro and cleavage of the signal sequence is followed by SDS polyacrylamide gel electrophoresis coupled with autoradiography. Radioactive amino acids have to be incorporated in the expressed protein, since the amount of the in vitro expressed protein is usually very low and processing of the signal peptide cannot be followed by SDS polyacrylamide gel electrophoresis alone. Here we describe a rapid and simple method to express large amounts of a protein precursor in E. coli. We have analyzed the effect of ionophors as well as of azide on the accumulation of expressed protein precursors. Azide blocks the function of SecA and the ionophors dissipate the electrochemical gradient across the cytoplasmic membrane of E. coli. Addition of azide ions resulted in the formation of inclusion bodies, highly enriched with pre-apo-plastocyanine. Plastocyanine is a soluble copper protein, which can be found in the periplasmic space of cyanobacteria as well as in the thylakoid lumen of cyanobacteria and chloroplasts, and the pre-protein contains a cleavable signal sequence at its N-terminus. After purification of cyanobacterial pre-apo-plastocyanine, its signal sequence can be cleaved off by the E. coli signal peptidase, and protein processing was followed on Coomassie stained SDS polyacrylamide gels. We are optimistic that the presented method can be further developed and applied.