• Analytical Science and Technology
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• v.12 no.3
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• pp.256-259
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• 1999

Tyrosinases are related to the enzymatic browning of plants and attract the major scientific interest for the prevention of it. Three tyrosinase isozymes ($P_1$, $P_2$ and $P_3$) from pine needles were purified to homogeneity and characterized the factors that affect their activities. The L-ascorbic acid and ${\beta}$-mercaptoethanol notably inhibited the enzymatic activities of the three isozymes. The sodium diethyldithiocarbamate was a competitive inhibitor of isozymes with the $K_i$ values of $P_1$(0.030 mM), $P_2$(0.015 mM) and $P_3$(0.019 mM), respectively. Their enzyme activities were however, increased by the addition of most metal ions. The optimum pH for the three isozymes was 9.0~9.5 and the optimum temperatures ranged from 55 to $60^{\circ}C$ using L-DOPA as substrate.

• Korean Journal of Plant Resources
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• v.19 no.3
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• pp.422-426
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• 2006

This research was conducted to get the basic materials necessary to obtain the somatic hybrid plant between Solanum sisymbriifolium and other Solanum species (S. integrifolium and S. toxicarium). Regarding the formation of colony from the protoplast in S. sisymbriifolium, S. integrifolium and the fused protoplast mixture; for the S. sisymbriifolium, a colony was observed in F medium(Kao medium containing $5.0mg{\cdot}L^{-1}\;NAA,\;1.0mg{\cdot}L^{-1}$ 2,4-D and $1.0mg{\cdot}L^{-1}$ BA); and for the S. integrifolium, in G medium (a half strength MS medium containing 0.03 M sucrose, 0.4 M mannitol, $1.0mg{\cdot}L^{-1}\;NAA,\;1.0mg{\cdot}L^{-1}$ kinetin) respectively. In mixed cultured protoplast after electriofusion treatment, the cell division and colony formation were observed in both media F and G. For the shoot and root formation rate, there was no difference between the parent of each breed and mixed protoplast regardless of the medium. In the fused protoplast mixture of S. sisymbriifolium and S. toxicarium, a colony formation was also observed in both media F and H(a half strength MS medium containing 0.03 M sucrose, 0.4 M mannitol, $1.0mg{\cdot}L^{-1}\;NAA,\;1.0mg{\cdot}L^{-1}$ kinetin); and there was no difference in the shoot and root formation rate between the parent and the mixed protoplast.

• Korean Journal of Plant Taxonomy
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• v.45 no.1
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• pp.1-7
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• 2015

Using starch gel electrophoresis, ten isozyme loci were examined in nine populations of Euphorbia ebracteolata in Korea. Populations of E. ebracteolata tend to have higher within-population levels of genetic variation (A = 2.2, P = 61.1, He = 0.165) along with low levels of genetic differentiation ($F_{ST}$ = 0.075) compared to previously reported Euphorbia species. The relatively high genetic variation in E. ebracteolata may be due to its long-lived regional distribution and to the outcrossed nature of the species. Low levels of genetic differentiation and the absence of unique alleles in E. ebracteolata populations suggest that Korean populations diverged recently. This study does not support the recognition of var. coreana and for. magna as separate taxa, and suggests that they should be combined with E. ebracteolata.

• The Korean Journal of Mycology
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• v.15 no.4
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• pp.250-253
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• 1987

The transfer of the isolated nuclei from P. florida into protoplasts of P. ostreatus was induced with polyethylene glycol and $CaCl_2$. Three types of transfer products of nuclei were obtained when transferred to MMM. Type 1 colonies were more vigrously growing mycelium and stable on MCM. One of the type 1 colonies, appeared segregation on MCM plus benomyl. The mycelium did not form clamp connection. These results suggest that type 1 colonies were nuclear hybrids or allodiploids. Type 2 was main products of nuclear transfer. The mycelium formed clamp connection and fertile on sawdust media. Type 3 was very slow growing or non-viable colonies after debris of nuclei or chromosomes transfer into recipient protoplasts. Isozyme pattern of esterase in type 1 produced a new band. Type 2 and type 3 could be characterized by parental bands.

• Molecules and Cells
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• v.19 no.1
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• pp.97-103
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• 2005

The role of residue C323 in catalysis by human glutamate dehydrogenase isozymes (hGDH1 and hGDH2) was examined by substituting Arg, Gly, Leu, Met, or Tyr at C323 by cassette mutagenesis using synthetic human GDH isozyme genes. As a result, the $K_m$ of the enzyme for NADH and ${\alpha}-ketoglutarate$ increased up to 1.6-fold and 1.1-fold, respectively. It seems likely that C323 is not responsible for substrate-binding or coenzyme-binding. The efficiency ($k_{cat}/K_m$) of the mutant enzymes was only 11-14% of that of the wild-type isozymes, mainly due to a decrease in $k_{cat}$ values. There was a linear relationship between incorporation of [$^{14}C$]p-chloromercuribenzoic acid and loss of enzyme activity that extrapolated to a stoichiometry of one mol of [$^{14}C$] incorporated per mol of monomer for wild type hGDHs. No incorporation of [$^{14}C$]p-chloromercuribenzoic acid was observed with the C323 mutants. ADP and GTP had no effect on the binding of p-chloromercuribenzoic acid, suggesting that C323 is not directly involved in allosteric regulation. There were no differences between the two hGDH isozymes in sensitivities to mutagenesis at C323. Our results suggest that C323 plays an important role in catalysis by human GDH isozymes.

• Journal of Microbiology and Biotechnology
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• v.22 no.3
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• pp.407-415
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• 2012

An endophytic bacterium, Bacillus thuringiensis GS1, was isolated from bracken (Pteridium aquilinum) and found to have maximal production of chitinase (4.3 units/ml) at 5 days after culture. This study investigated the ability of B. thuringiensis GS1 to induce resistance to Rhizoctonia solani KACC 40111 (RS) in cucumber plants. Chitinase activity was greatest in RS-treated plants at 4 days. ${\beta}$-1,3-Glucanase activity was highest in GS1-treated plants at 5 days. Guaiacol peroxidase (GPOD) activity increased continuously in all treated plants for 5 days. Ascorbate peroxidase (APX) activity in RS-treated plants was increased 1.5-fold compared with the control at 4 days. Polyphenol oxidase (PPO) activity in RS-treated plants was increased 1.5-fold compared with the control at 3 days. At 5 days after treatment, activity staining revealed three bands with chitinase activity (Ch1, Ch2, and Ch3) on SDS-PAGE of cucumber plants treated with GS1+RS, whereas only one band was observed for RS-treated plants (Ch2). One GPOD isozyme (Gp1) was also observed in response to treatment with RS and GS1+RS at 4 days. One APX band (Ap2) was present on the native-PAGE gel of the control, and GS1- and GS1+RS-treated plants at 1 day. PPO bands (Po1 and Po2) from RS- and GS1+RS-treated plants were stronger than in the control and GS1-treated plants upon native-PAGE at 5 days. Taken together, these results indicate that the induction of PR proteins and defense-related enzymes by B. thuringiensis GS1 might have suppressed the damping-off caused by R. solani KACC 40111 in cucumber plants.

• Preventive Nutrition and Food Science
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• v.8 no.2
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• pp.130-136
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• 2003

The protective effects of onion extract (OE), onion powder extracted in ethanol for 2 days. on carbon tetrachloride ($CCl_4$)-induced hepatotoxicities and the possible mechanisms involved in this protection were investigated in mice. Pretreatment with OE prior to the administration of $CCl_4$ significantly reduced the increase in serum alanine and aspartate aminotransferase activities and hepatic lipid peroxidation in a dose-dependent manner. In addition, pretreatment with OE significantly prevented the depletion of reduced glutathione content in the liver of $CCl_4$-intoxicated mice. $CCl_4$-induced hepatotoxicity was also prevented, as indicated by a liver histopathologic findings. The effects of OE on the cytochrome P450 (P450) 2E1, the major isozyme involved in $CCl_4$ biotransformation were investigated. Treatment of mice with OE resulted in a significant decrease in P450 2E1-dependent p-nitrophenol and aniline hydroxylation in a dose-dependent manner. Consistent with these observations, the P450 2E1 expressions were also decreased, as determined by immunoblot analysis. OE also exhibited antioxidant effects in FeCl$_2$-ascorbate induced lipid peroxidation in rat liver homogenates and in superoxide radical scavenging activity. These results show that the protective effects of OE against the $CCl_4$-induced hepatotoxicity may be due to its ability to block bioactivation of $CCl_4$, mainly tty inhibiting the expression and activities of P450 2E1 and by scavenging free radicals.

• Korean journal of applied entomology
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• v.26 no.3 s.72
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• pp.165-170
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• 1987

This experiment was carried out to evaluate the difference in the biochemical characteristic of the brown planthoppers of the insecticide risistant, susceptible strains and their hybrid progenies. Activity of the esterase isozyme separated by electrophoresis method was remarkably high in the resistant strain as compared with the susceptible strain. Esterase activity between the insecticide-treated strains and the non-insecticide strains was not degraded in the resistant strain and the $F_1$, but remarkably degraded in the susceptible strain. The increase of esterase activity was associated with the development of resistance, and that was inherited with a dominant gene.

• Korean Journal of Plant Taxonomy
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• v.36 no.4
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• pp.293-308
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• 2006

Genetic and morphological studies using morphological and isozymic data from 20 populations of 6 Korea Hylotelephium were conducted to resolve the species relationships and the origin of polyploid species. The results of morphological studies suggest that triploid H. viviparum is closely related to H. verticillatum, and the high frequency alleles of two species were very similar each other in isozyme analyses. Unique fixation of $PGI-1^b$ in two species supports that H. verticillatum should be the diploid ancestor of H. viviparum. However, a unique $ALD-1^c$ allele is present in H. viviparum, and the lack of the common alleles of H. erythrostictum and H. spectabile in this species eliminated them from the candidates of another tetraploid ancestor of H. viviparum. Based on the high morphological and genetic similarities, our results supported that the Korea endemic H. viridescens might be originated from the H. erythrostictum or share a common ancestor with it. Besides, H. ussuriense is closely related with H. erythrostictum and H. viridescens.

• The Korean Journal of Zoology
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• v.36 no.3
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• pp.425-432
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• 1993

Alkaline phosphatase from Culex pipiens pallens was examined to determine the optimal assay condition and to assay the activity during ovarian development. The activity of alkaline phosphatase in a male and a nongravid female continuously were declined after eclosion. But by the stimulus of a blood meal, the enzyme activity was increased dramatically. At 30 hr. after a blood meal, the maximal activity was reached and then declined. And after 48 hr. after a blood meal, the second activity increase was revealed. This second increase was maintained up to oviposition. The first activity increase was revealed in the midgut and the second increase was done in the ovary to assay the organ distribution of alkaline phosphatase. In electrophresis data, it was shown 5 isozyme bands, ALP-1 and ALP-2 in the ovary, ALP-3 in the thorax and the midgut, and ALP-4 and ALP-5 in the thorax, the fatbody and the midgut in crude extract at 30 hr. after a blood meal. One the same ovary pattern were shown at 72 hr. after a blood meal.