• Biomedical Science Letters
• /
• v.9 no.2
• /
• pp.75-84
• /
• 2003

To evaluate the influence of hepatic oxygen free radical systems on liver injury by topical p-phenylenediamine (PPD) application on rat skin, PPD (25 mg/16.5 $\textrm{cm}^2$) was topically applied to the abdominal region 5 times every other day and sacrificed. By PPD treatment, increasing rate of liver weight/body weight (%), serum activities of alanine aminotransferase and aspartate aminotransferase and decreasing rate of microsomal glucose-6-phosphatase activity were higher in the rats fed tungstate supplemented diet than those fed a standard diet. These findings indicate that group fed tungstate supplemented diet have more severe liver injury compared with group fed standard diet on topical PPD application. However, the activities of oxygen free radical generating enzymes such as xanthine oxidase (XO) and cytochrome P450 dependent aniline hydroxylase and those of oxygen free radical scavenging enzymes were not found to be different between these two animal groups. In the present study, a novel monitoring method to detect the generating of oxygen free radicals in liver extract was devised. Throughout this method, the oxidized PPD produced by oxygen free radicals was determined colorimetrically. The increasing rate of PPD oxidation by liver homogenate was higher in tungstate fed animals than in standard diet fed ones. Among the fractionations of liver extract, the mitochondrial and postmitochondrial fractions in the liver extract of tungstate fed animals led to a higher availability of PPD oxidation by PPD treatment compared with standard diet fed ones. In conclusion, these results suggest that an enhanced liver injury in tungstate fed animals treated with PPD may be due to oxygen free radicals produced in other systems except oxygen free radicals generating from cytosolic XO system. Especially, oxidative availability by PPD can be used for oxygen free radical detection in some tissue.

• Journal of Marine Bioscience and Biotechnology
• /
• v.16 no.1
• /
• pp.36-44
• /
• 2024

This study attempted to improve the growth of the freshwater microalgae, Parachlorella kessleri, through the sequential optimization of culture conditions. This attempt aimed to enhance the microalgae's ability to fixate atmospheric CO₂. Culture temperature and light intensity appropriate for microalgal growth were scanned using a high-throughput photobioreactor system. The supplied air flow rate varied from 0.05 to 0.3 vvm, and its effect on the growth rate of P. kessleri was determined. Next, sodium phosphate buffer was added to the culture medium (BG11) to enhance CO₂ fixation by increasing the availability of CO₂(HCO₃^-) in the culture medium. The results indicated that optimal culture temperature and light intensity were 20℃-25℃ and 300 μE/m²/s, respectively. Growth rates of P. kessleri under various air flow rates highly depended on the increase of the culture's flow rate and pH which determines CO₂ availability. Adding sodium phosphate buffer to BG11 to maintain a constant neutral pH (7.0) improved microalgal growth compared to control conditions (BG11 without sodium phosphate). These results indicate that the CO₂ fixation rate in the air could be enhanced via the sequential optimization of microalgal culture conditions.

• Journal of Ecology and Environment
• /
• v.39 no.1
• /
• pp.1-10
• /
• 2016

Despite it has been mentioned that the successful restoration in landscape level was achieved in the Young-il soil erosion control project, quantitative evaluation of restored plant communities (Alnus firma as introduced species and Pinus thunbergii as native species) was hardly founded. Light availability, litter and woody debris cover, and forest structure and composition were determined for 500 m² band-quadrat in three forest types. Abiotic factors of Q. serrata stands, as reference forest, and A. firma stands were similar but not for P. thunbergii stands. There were no significant difference on mean stem density (stems ha^-1, H = 3.6, p = 0.162), and the mean basal area of each stand had marginal significance (m² ha^-1, H = 5.7, p = 0.058) among stands as total basal area was higher with the order of A. firma (21.4 m² ha^-1), P. thunbergii (19.8 m² ha^-1) and Q. serrata (16.2 m² ha^-1). Restoration of vegetation structure was more effective in fast-growing and N-fixing A. firma, as introduced species plantation. However, result of MRPP, NMS ordination and ISPAN for herbaceous layer, not for tree and shrub species composition, indicated that restoration of ground vegetation was likely influenced highly from local environment. Propagule availability from landscape context such as connectedness to natural vegetation and management practices in restored isolated stands are available explanations for restoration effects and gaps between restored plantations and secondary oak forest.

• Journal of Microbiology and Biotechnology
• /
• v.30 no.11
• /
• pp.1777-1784
• /
• 2020

To increase the availability of microalgae as producers of valuable compounds, it is necessary to develop novel systems for gene expression regulation. Among the diverse expression systems available in microalgae, none are designed to induce expression by low temperature. In this study, we explored a cold-inducible system using the antifreeze protein (AFP) promoter from a polar diatom, Chaetoceros neogracile. A vector containing the CnAFP promoter (pCnAFP) was generated to regulate nuclear gene expression, and reporter genes (Gaussia luciferase (GLuc) and mVenus fluorescent protein (mVenus)) were successfully expressed in the model microalga, Chlamydomonas reinhardtii. In particular, under the control of pCnAFP, the expression of these genes was increased at low temperature, unlike pAR1, a promoter that is widely used for gene expression in C. reinhardtii. Promoter truncation assays showed that cold inducibility was still present even when pCnAFP was shortened to 600 bp, indicating the presence of a low-temperature response element between -600 and -477 bp. Our results show the availability of new heterologous gene expression systems with cold-inducible promoters and the possibility to find novel low-temperature response factors in microalgae. Through further improvement, this cold-inducible promoter could be used to develop more efficient expression tools.

• Korean Journal of Soil Science and Fertilizer
• /
• v.10 no.1
• /
• pp.55-60
• /
• 1977

In order to study the availability of soil P and applied P to rice plant under water-logged system, a pot experiment with five soils having different levels of available P (24, 64, 100, 144 and 231 ppm) under four levels of applied P (0, 30, 60 and 90 ppm) was conducted. The availability of P was measured in terms of plant performance and the behaviors of P in soils were studied through the fractionation of various forms of P and by measuring the adsorption and desorption characteristics. The results are summarized us following. 1. The rice plant responded to applied P in the soils containing less than 144 ppm of available P as measured by Lancaster's method in terms of number of tillers in early growth stages. However, when the response of rice plant to applied P was evaluated in terms of grain yield there was no response even in the soil containing 24 ppm of available P. 2. Applied P was fixed as Al-P at the early stages and converted into Fe-P at later stages. 3. The P adsorption maxima of soils measured by Langmuir's isotherm ranged from 70 to 100mg/100g. No relationships between the level of available P and P adsorption maxima were observed. 4. There was a trend that the higher the level of available P, the higher the release of water soluble p. 5. The reduction of soil increased the level of available P by the factor of 1.8 times of air dried soils.

• Asian-Australasian Journal of Animal Sciences
• /
• v.23 no.1
• /
• pp.74-81
• /
• 2010

The effects of different levels of natural clay enterosorbent on the growth, nutrient availability, and genital organs of post-weaning female pigs fed with an addition of zearalenone (ZEA) were investigated in the study. A total of thirty-five post-weaning gilts ($L{\times}Y{\times}D$) with an average body weight of 12.36${\pm}$1.46 kg were used in the test. The gilts were raised individually in metabolism cages and fed a corn-soybean meal-whey basal diet with an addition of 0 or 1 mg/kg of ZEA for 24 d with four levels of natural clay enterosorbent added in the feed. The treatments were: i) control; ii) control+2.5 g/kg clay; iii) control+1 mg/kg ZEA; iv) control+1 mg/kg ZEA+1.25 g/kg clay; v) control+1 mg/kg ZEA+2.5 g/kg clay; vi) control+1 mg/kg ZEA+5.0 g/kg clay; vii) control+1 mg/kg ZEA +10 g/kg clay. Pigs fed diets contaminated with additional purified ZEA had significantly reduced apparent digestibility of crude protein (CP), gross energy (GE) and apparent metabolic rate of GE (ME/GE, p<0.05) without changes of net protein utilization (NPU, p>0.05). Final body weight, average daily gain (ADG), average daily feed intake (ADFI), vulva length, vulva width, vulva area, relative weights of genital organ and proliferative changes of the ovary tissues in gilts fed ZEA-contaminated diet were increased (p<0.05) compared to the gilts fed the control diet. Addition of natural clay enterosorbent in the ZEA-contaminated diet showed a positive protection effect on ZEA feeding, and the protection was increased linearly or quadratically as clay content increased. However, in pigs fed a diet with clay alone at 2.5 g/kg level there was no significant impact (p>0.05) on all the parameters as compared to the control. It is suggested that feeding ZEA at about 1.0 mg/kg for 24 days might result in a deleterious effect in pigs, and addition of 5 or 10 g clay enterosorbent per kg diet can effectively neutralize the detrimental effects of the ZEA feeding.

• 한국생물공학회:학술대회논문집
• /
• 2001.11a
• /
• pp.771-774
• /
• 2001

NADPH has been known as a regulating factor the biosynthesis of polyhydroxyalkanote(PHA), and the flux of NADPH for PHA biosynthesis could be enforced by the amplification of zwf gene encoding glucose 6-phosphate dehydrogenase. The recombinant plasmid pCZWF harboring PHA synthase, phbC from R. eutropha and zwf from E. coli were constructed, and were transformed to R. eutropha by electroporation. The biosynthesis of P(3HB-3HV) copolymer were carried out in transformant R. eutropha through the two-stage cultivation method using valerate as a precursor. The biosynthesis rate and PHA content of transformant R. eutropha harboring pCZWF were increased compared with transformant R. eutropha harboring only phbC. Especially, the molar fraction of 3HV was increased from 68% to 74% due to amplification of zwf gene. And the biosynthesis P(3HB-3HV) and P(3HB-4HB) carried out using propionate and ${\gamma}-butyrolactone$ as a precursor, respectively. But the rate, content, and molar fraction of biosynthesis copolymers were not influenced appreciably. This may be due to the reduced availability of NADPH.

• Preventive Nutrition and Food Science
• /
• v.5 no.2
• /
• pp.81-85
• /
• 2000

Bromelain has been used as a meat-tenderizing agent in food processing. To increase the availability of bromelain, microencapsulation into liposome was carried out by the dehydration and rehydration method. Small unilamellar vesicles prepared by sonication treatment showed higher encapsulation efficiency (EE) than by the French press method. In the preparation of liposome, the effect of pH and centrifugal force on EE was also investigated and it showed a higher EE at acidic pH than at alkaline pH with centrifugation at 80, 000$\times$g. The actual EEs except unencapsulated bromelain which bound on the outside surface of liposome by electrostatic interaction also were investigated, and the optimal EE was at pH 4.6, at 0.6 of a ratio of bromelain to phosholipid(18.2%, w/w). Release of bromelain from liposomes was stimulated as the temperature increased at neutral pH.

• Journal of Korean Society of Forest Science
• /
• v.99 no.3
• /
• pp.397-403
• /
• 2010

This study was conducted to investigate the changes in soil temperature, soil moisture content, light availability (photosynthetically active radiation, PAR) and diameter growth in 46-year-old Korean pine (Pinus koraiensis Siebold et Zuccarini) plantation located in Gwangneung experimental forest after 4 years from thinning. Three different thinning intensities [control, 45%(T45), and 60%(T60) basal area reduction] were applied in 2004. Mean soil temperature and soil water content were $8.9^{\circ}C$ and 14.3% for control, $10^{\circ}C$ and 16.1% for T45 and $10.2^{\circ}C$ and 16.1% for T60, respectively. Mean soil temperature and moisture content were significantly different among the treatment plots (p<0.05). Mean PAR in control, T45 and T60 was 44, 143 and178 ${\mu}mol/m^2$/sec, respectively and the differences were also statistically significant among the treatment plots (p<0.05). Mean annual diameter growth in control, T45 and T60 was 0.4, 1.5 and 1.2 mm, respectively. Diameter growth of Pinus koraiensis was steadily increased after thinning in comparison to control. Consequently, the results suggested that soil temperature, soil moisture content and light availability were likely to last beyond the 4 years after thinning in this Korean pine plantation.

• Journal of Power System Engineering
• /
• v.4 no.4
• /
• pp.99-107
• /
• 2000

In this study several P type and N type ceramic semiconductors were prepared by atomic valence control and their electric resistivities were investigated with various concentrations of additive impurities. N-P junctions were made by thin film printing method and their varistor-like characteristics were investigated and their availability was discussed. The results are followings, 1) Some N type semiconductors with a proper concentration of additive impurity have minimum resistivities. 2) The N-P junction samples with ZnO as a constituent material of N type semiconductor have linearity in voltage-current characteristics, but the other N-P junction samples have the non-linearity, 3) Some N-P junction samples showed the good varistor-like characteristics.