• Molecules and Cells
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• v.21 no.2
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• pp.229-236
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• 2006

Gaegurin 4 (GGN4), a novel peptide isolated from the skin of a Korean frog, Rana rugosa, has broad spectrum antimicrobial activity. A number of amphipathic peptides closely related to GGN4 undergo a coil to helix transition with concomitant oligomerization in lipid membranes or membrane-mimicking environments. Despite intensive study of their secondary structures, the oligomeric states of the peptides before and after the transition are not well understood. To clarify the structural basis of its antibiotic action, we used analytical ultracentrifugation to define the aggregation state of GGN4 in water, ethyl alcohol, and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP). The maximum size of GGN4 in 15% HFIP corresponded to a decamer, whereas it was monomeric in buffer. The oligomeric transition is accompanied by a cooperative 9 nm blue-shift of maximum fluorescence emission and a large secondary structure change from an almost random coil to an ${\alpha}$-helical structure. GGN4 induces pores in lipid membranes and, using electrophysiological methods, we estimated the diameter of the pores to be exceed $7.3{\AA}$, which suggests that the minimal oligomer structure responsible is a pentamer.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.179.3-179.3
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• 2003

Natural histrionicotoxin, a substance isolated from the skins of the "arrow poison frog" and its fully hydrogenated derivative, perhydrohistrionicotoxin (pHTX), have been the subject of synthetic investigation because of their important neurophysiological activity and a unique framework. In this work, we could obtained the appropriately functionalized spiropiperidine compound as a formal precursor of perhydrohistrionicotoxin. An important feature of this synthesis is the creation of a stereogenic center by using Ireland-Claisen Rearrangement, and Ring-Closing Metathesis (RCM).sis (RCM).

• Korean Journal of Ecology and Environment
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• v.54 no.4
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• pp.363-373
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• 2021

An ecological niche is defined as the specific role of a species influenced by time, space, and other resources. By investigating overlaps between ecological niches of different species, we could estimate the degrees of interspecific competition. Such studies often use geographic information systems (GIS) to discover niche overlaps between species. In this study, we used GIS to estimate the spatial niches of two Korean frog species(Pelophylax nigromaculatus and P. chosenicus). This enabled us to predict their geographic distributions in order to identify their coexistence regions and distribution patterns. The results confirmed that altitude was an important variable for predicting their distribution, with a correlation with their climatic range. Spatial distributions of the two frog species were highly overlapped, as the distribution range for P. nigromaculatus included most of the range of P. chosenicus, showing a sympatric distribution pattern. Within the coexisting regions, however, the presence sites for the two species did not overlap, implying weak competition. To confirm the principal factors influencing their competitive relationship and reasons for their sympatric distribution pattern, we need more detailed in-depth studies on the diverse environmental variables within the regions where the two species coexist. By doing so, we would be able to identify various mechanisms for avoiding competition in sympatric frog species.

• BMB Reports
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• v.40 no.2
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• pp.261-269
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• 2007

The structure and dynamics of a 37-residue antimicrobial peptide gaegurin 4 (GGN4) isolated from the skin of the native Korean frog, Rana rugosa, was determined in SDS micelles by NMR spectroscopy. The solution structure of the peptide in SDS micelles was determined from 352 NOE-derived distance constraints and 22 backbone torsion angle constraints. Dynamic properties for the amide backbone were characterized by $^1H-^{15}N $heteronuclear NOE experiments. The structural study revealed two amphipathic helices spanning residues 2-10 and 16-32 and that the helices were connected by a flexible loop. An intraresidue disulfide bridge was formed between residues Cys31 and Cys37 near the C-terminus. The loop region (11-15) connecting the two helices are were slightly more flexible than these helices themselves. From the fact that since there is no contact NOEs between two helices, it is implied that the GGN4 peptide shows an independent motion of both helices which has an angle of about $ 60^{\circ}-120^{\circ}$ from each other.

• Genomics & Informatics
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• v.3 no.1
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• pp.24-29
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• 2005

TRPV2 is a non-specific cation channel expressed in sensory neurons, and activated by noxious heat. Particularly, TRPV2 has six transmembrane domains and three ankyrin repeats. TRPV2 has been cloned from various species such as human, rat, and mouse. Oocytes of Xenopus laevis - an African clawed frog ­have been widely used for decades in characterization of various receptors and ion channels. The functional property of rat TRPV2 was also identified by this oocyte expression system. However, no TRPV2 orthologue of Xenopus laevis has been reported so far. Hence, we have focused to clone a TRPV2 orthologue of Xenopus laevis with the aid of bioinformatic tools. Because the genome sequence of Xenopus laevis is not available until now, a genome sequence of Xenopus tropicalis - a close relative species of Xenopus laevis - was used. After a number of bioinformatic searches in silico, a predicted full-length sequence of TRPV2 orthologue of Xenopus tropicalis was found. Based on this predicted sequence, various approaches such as RT-PCR and 5' -RACE technique were applied to clone a full length of Xenopus laevis TRV2. Consequently, a full-length Xenopus laevis TRPV2 was cloned from heart cDNA.

• Korean Journal of Ecology and Environment
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• v.53 no.3
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• pp.221-228
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• 2020

We studied the development of the endangered gold-spotted pond frog, Pelophylax chosenicus eggs and analyzed growth and survival rate of the tadpoles while feeding different feed to obtain the basic data on the its biological traits and reproduction. We observed the fertilized eggs of gold-spotted pond frog that naturally spawned in a breeding tank using a microscope. Fertilized eggs were sphere shape surrounded by colloid layers, clearly distinct with animal and plant poles. The fertilized eggs hatched 31 hours after fertilization and operculum complete at 175 hours after fertilization at water temperature of 27.0±1.0℃. As a result of growth and survival rate by different feed from 35 days after mouth open stage, vegetable feed (VF) group and tetra-min (T) group were significantly higher average weight gain rate (WG)(5843.9% and 5736.3%, respectively) and average specific growth rate (SGR) (11.67% and 11.62, respectively) compared with other groups (WG: 641.8~4625.2%, SGR: 5.72~11.01%). The vegetable (V) group showed the lowest growth rate (P<0.05). The average feed efficiency was 177.83% in the VF group, about 17 times higher than the V group. In addition, the average survival rate of the VF and T groups were the high at 97.5% and 100%, respectively, and the V group was the lowest at 32.5%. Therefore, the more efficient feeds for successful breeding is singly with VF or T.

• Parasites, Hosts and Diseases
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• v.44 no.2 s.138
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• pp.151-156
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• 2006

A case of breast sparganosis was confirmed by surgical excision of a worm (fragmented into 5 pieces) in a 59-year-old Korean woman suffering from a palpable mass in the left breast. Mammography and ultrasonography characteristically revealed the presence of several well-defined, isodense and hypoechoic tubular masses, in the upper quadrant of the left breast, each mass consisting of a continuous cord- or worm-like structure. During surgery, a long segment of an actively moving sparganum of Spirometra sp. and 4 small fragments of the same worm, giving a total length of 20.3 cm, were extracted from the upper outer quadrant of the left breast and the axillary region. The infection source remains unclear, because the patient denied ingesting any snake or frog meat or drinking untreated water.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.13 no.1
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• pp.75-85
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• 1983

Age differences in the skin structure have been studied in young (one year-old) and aged (five and a half year-old) frogs, Xenopus laevis. The epidermis in young frogs is made up of an average of 6.3 and 4.7 layers of epithelial cells at abdominal and dorsal surfaces, respectively. In aged frogs, the number of respective cell layers at abdominal and dorsal surfaces increases to 8.8 and 5.6. The thickness of the dermis (spongiosum) in aged frogs is decreased 25% on the abdominal side (from 267㎛ to 207㎛) but is increased by 11 % on the dorsal side (from 275㎛ to 305㎛). The nucleolar index and ³H-uridine incorporation, as judged by radioautography, by epithelial cells are drastically reduced in aged frogs.

• The Korean Journal of Physiology and Pharmacology
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• v.13 no.1
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• pp.39-47
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• 2009

Gaegurin 4(GGN 4), an antimicrobial peptide isolated from a Korean frog, is five times more potent against Gram-positive than Gram-negative bacteria, but has little hemolytic activity. To understand the mechanism of such cell selectivity, we examined GGN4-induced $K^+$ efflux from target cells, and membrane conductances in planar lipid bilayers. The $K^+$ efflux from Gram-positive M. luteus(2.5 ${\mu}g/ml$) was faster and larger than that from Gram-negative E. coli(75 ${\mu}g/ml$), while that from RBC was negligible even at higher concentration(100 ${\mu}g/ml$). GGN4 induced larger conductances in the planar bilayers which were formed with lipids extracted from Gram-positive B. subtilis than in those from E. coli(p<0.01), however, the effects of GGN4 were not selective in the bilayers formed with lipids from E. coli and red blood cells. Addition of an acidic phospholipid, phosphatidylserine to planar bilayers increased the GGN4-induced membrane conductance(p<0.05), but addition of phosphatidylcholine or cholesterol reduced it(p<0.05). Transmission electron microscopy revealed that GGN4 induced pore-like damages in M. luteus and dis-layering damages on the outer wall of E. coli. Taken together, the present results indicate that the selectivity of GGN4 toward Gram-positive over Gram-negative bacteria is due to negative surface charges, and interaction of GGN4 with outer walls. The selectivity toward bacteria over RBC is due to the presence of phosphatidylcholine and cholesterol, and the trans-bilayer lipid asymmetry in RBC. The results suggest that design of selective antimicrobial peptides should be based on the composition and topology of membrane lipids in the target cells.

• The Korean Journal of Pharmacology
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• v.11 no.1 s.17
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• pp.7-13
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• 1975

In Chinese medicine, it is said that Aconiti tuber has cardiotonic, diuretic and analgesic effects. Kim et al reported that alkaloid free part of Aconiti tuber, $CHCI_3$ insoluble fraction, showed inotropic effect on isolated frog heart and inotropic effect is potenciated by n-butanol fractionation. To investigate the effect of Aconiti tuber butanol fraction on the mechanical and electrical properties of heart, change of active tension, excitability and refractory period of isolated rabbit atrium in the presence of butanol fraction were measured and the comparison with that of ouabain and quinidine was done. The observed results are as follows. 1. $5{\times}10^{-4}g/ml$ concentration of Aconiti tuber butanol fraction showed approximately same effect with therapeutic concentration of ouabain on the increment of contractile force, and the effect of $2{\times}10^{-3}g/ml$ was greater than that of $1{\times}10^{-5}g/ml$ of ouabain. 2. Acceleration of rate of contractile force increment in the presence of Aconiti tuber butanol fraction was greater than in ouabain, and the time to maximum tension was shorter in Aconiti tuber butanol fraction than in ouabain. 3. The excitability of isolated atrium was slightly increased at low concentration of Aconiti tuber butanol fraction, while decreased at higher concentration. 4. Aconiti tuber butanol fraction slightly prolonged refractory period of isolated right atrium at the concentration of $2{\times}10^{-3}g/ml$.