• Korean Journal of Medicinal Crop Science
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• v.7 no.3
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• pp.155-161
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• 1999

This study was carried out to develop the propagation system using in vitro induced- microtubers of yams (Dioscorea alata L.). Effects of kinds of media, mineral composition, sucrose concentration (0, 2, 4, 6, 8, 10%), photoperiod (0, 8, 12, 16, 24h), and growth regulators (NAA, IAA, ZR, JA-Me, ABA) on the development of microtubers, roots, and shoots in nodal stem segment cultures of D. alata L. were evaluated. Microtuberization in nodal stem segment occurred on all the media supplemented with growth regulator and sucrose. Among basic media, 1/2MS medium was the best in microtuber induction. NAA was shown to be the most effective among the growth regulators. Optimal NAA concentration was 1mg/l. The microtuberization was the highest at the concentration of 6% sucrose. When the nodal stem segment were cultured under darkness, the tuberization was increased markedly compared to those cultured under light condition. It was also noticeable that the culture in medium with NAA produced only microtubers and roots, but no shoots, in nodal segments. In this study, the optimal medium composition for microtuberization in nodal stem segment was found to be 1/2MS medium supplemented with 1mg/l NAA and 6% sucrose under dark condition at $25^{\circ}C$.

• Korean Journal of Weed Science
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• v.17 no.2
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• pp.163-168
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• 1997

The experiment was conducted in 1996 to investigate distribution, germination characteristics, and effective control of Abutilon theophrasti in corn fields. The regional distribution of A. theophrasti showed that it was higher in Gyenggi province than in Kangwon, Chungnam, or Chonllanambug provinces because of many dairy farms located in Gyenggi province where fresh corn was used as ensilage. The optimal temperature of the weed seed germination was around 15~$20^{\circ}C$ and germination rate was 73~93% in 1~5cm of burial depth. The weed was able to be controlled effectively when treated 10 days after seeding more than just after seeding with herbicides, pendimethalin 31.7% EC, linuron 50% WP and pendimethalin linuron 25% EC with an acceptable phytotoxicity.

• Journal of Microbiology and Biotechnology
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• v.30 no.6
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• pp.937-945
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• 2020

N-acyl-homoserine lactone (AHL)-mediated quorum sensing (QS) plays a major role in development of biofilms, which contribute to rise in infections and biofouling in water-related industries. Interference in QS, called quorum quenching (QQ), has recieved a lot of attention in recent years. Rhodococcus spp. are known to have prominent quorum quenching activity and in previous reports it was suggested that this genus possesses multiple QQ enzymes, but only one gene, qsdA, which encodes an AHL-lactonase belonging to phosphotriesterase family, has been identified. Therefore, we conducted a whole genome sequencing and analysis of Rhodococcus sp. BH4 isolated from a wastewater treatment plant. The sequencing revealed another gene encoding a QQ enzyme (named jydB) that exhibited a high AHL degrading activity. This QQ enzyme had a 46% amino acid sequence similarity with the AHL-lactonase (AidH) of Ochrobactrum sp. T63. HPLC analysis and AHL restoration experiments by acidification revealed that the jydB gene encodes an AHL-lactonase which shares the known characteristics of the α/β hydrolase family. Purified recombinant JydB demonstrated a high hydrolytic activity against various AHLs. Kinetic analysis of JydB revealed a high catalytic efficiency (k_cat/K_M) against C4-HSL and 3-oxo-C6 HSL, ranging from 1.88 x 10⁶ to 1.45 x 10⁶ M^-1 s^-1, with distinctly low K_M values (0.16-0.24 mM). This study affirms that the AHL degrading activity and biofilm inhibition ability of Rhodococcus sp. BH4 may be due to the presence of multiple quorum quenching enzymes, including two types of AHL-lactonases, in addition to AHL-acylase and oxidoreductase, for which the genes have yet to be described.

• Korean Journal of Food Science and Technology
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• v.48 no.4
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• pp.323-328
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• 2016

In this study, specific and rapid enrichment and growth conditions for the most important, classic non-O157 enterohemorrhagic Escherichia coli (EHEC) serogroups were assessed. Three enrichment broth types, namely, EC medium with MUG broth, BRILA broth, and mTSB broth with novobiocin, were compared to identify the optimum enrichment broth for EHEC isolation. Four kinds of selective media, namely, ENDO agar, Chromocult agar, TBX agar, and CHROMagar$^{TM}$ STEC medium, were compared to identify the optimum one for non-O157 EHEC isolation. The results suggested that incubation in EC medium with MUG broth at $42^{\circ}C$ for 20 h is optimum for the enrichment of non-O157 EHEC. TBX agar was identified to have the highest specificity among the tested media. Consequently, a combination of complementary selective media according to serotype must be considered for comprehensive isolation of specific EHEC.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.2
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• pp.110-114
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• 2000

Effects of the combinations of six oxygen concentrations ($control, 0.6, 1.0, 2.0, 3.4 and 7.4 mg DO/l$) and two salinity levels ($20{\%_{\circ}} and 32{\%_{\circ}}$) on the rates of oxygen consumption, ammonia excretion and mortality of the mysid, Neomysis awatschensis were tested at $20{\circ}C$. The lethal level ($96 hr-LC-(50)$) of dissolved oxygen for mysid at $20{\%_{\circ}} and 32{\%_{\circ}} were 2,20 mg DO/l and 1.60 mg DO/l$ respectively, and all mysids died within $24hr at 0.6 mg DO/l$. Oxygen consumption rate of mysid was increased with dissolved oxygen increase at $20{\%_{\circ}} and 32{\%_{\circ}}$, but ammonia excretion rate was high af $1.0 mg DO/l$ during 96h exposure to DO concentration, and significantly greater in $20{\%_{\circ}} than 32{\%_{\circ}}$. $O:N$ ratio of mysid exposed during 96hr with salinity anil dissolved oxygen was below $10 at 20{\%_{\circ}} and 1,0{\~}2.0 mg DO/l, and was 4.4 at 32{\%_{\circ}} and 1.0 mg DO/l$. These results indicated that mysids were capable of changing their energy substrate in response to salinity and DO changes, and obtaining energy from proteins.

• The Korean Journal of Physiology and Pharmacology
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• v.3 no.4
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• pp.447-454
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• 1999

The production of nitric oxide (NO) and the expression of inducible nitric oxide synthase (iNOS) are known to be modulated by a variety of factors. Recent study showed that endotoxin-induced NO synthesis and iNOS expression were greatly enhanced by elevation of extracellular glucose concentration in murine macrophages. Although this was suggested to be due to the activation of protein kinase C (PKC) via sorbitol pathway, there was lack of evidence for this speculation. This study was performed to delineate the underlying intracellular mechanisms of glucose-enhancing effect on endotoxin-induced NO production in Raw264.7 macrophages. The levels of NO release induced by lipopolysaccharide (LPS) significantly increased by the treatment of glucose in a concentration dependent manner and also, this effect was observed in LPS-preprimed cells. Concurrent incubation of cells with PKC inhibitors, H-7 or chelerythrine, and LPS resulted in the diminution of NO production regardless of glucose concentration but this was not in the case of LPS-prepriming, that is, chelerythrine showed a minimal effect on the glucose- enhancing effect. PMA, a PKC activator, did not show any significant effect on glucose-associated NO production. Modulation of sorbitol pathway with zopolrestat, an aldose reductase inhibitor, did not affect LPS-induced NO production and iNOS expression under high glucose condition. And also, sodium pyruvate, which is expected to normalize cytosolic $NADH/NAD^+$ ratio, did not show any significant effect at concentrations of up to 10 mM. Glucosamine marginally increased the endotoxin-induced nitrite release in both control and high glucose treated group. 6-diazo-5-oxonorleucine (L-DON) and azaserine, glutamine: fructose- 6-phosphate amidotransferase (GFAT) inhibitors, significantly diminished the augmentation effect of high glucose on endotoxin-induced NO production. On the other hand, negative modulation of GFAT inhibitors was not reversed by the treatment of glucosamine, suggesting the minimal involvement, if any, of glucosamine pathway in glucose-enhancing effect. In summary, these results strongly suggest that the hexosamine biosynthesis pathway and the activation of PKC via sorbitol pathway do not contribute to the augmenting effect of high glucose on endotoxin induced NO production in macrophage-like Raw264.7 cells.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.3
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• pp.328-335
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• 2009

This study was undertaken to investigate the influence of exposure and removal of four different cryoprotectants (CPAs) on the ATP content of cumulus cell-enclosed (COs) and cumulus cell-denuded (DOs) immature porcine oocytes. The in vitro nuclear maturation of the COs, exposed to and removed from the CPAs was also assessed. Both COs and DOs were exposed to 1.5 M concentrations of each CPA (ethylene glycol (EG); propylene glycol (PG); dimethyl-sulfoxide (DMSO); and glycerol (G)) for durations of 5, 15, and 30 minutes at room temperature ($23.5{\pm}1.5^{\circ}C$), and immersed in physiological saline supplemented with 20% (v/v) fetal bovine serum for 5 minutes ($39^{\circ}C$) to remove each CPA. Before, during and after exposure to each CPA, the ATP content of both the COs and the DOs was measured. After removal from each CPA an aliquot of the COs was matured for 44${\pm}$2 h, and their nuclear maturation rates were measured up to the metaphase stage of the second meiotic division (the M-II stage). The maturation rates up to the M-II stage were not significantly different between all the groups that were exposed to each CPA for 5 minutes. For 15 and 30 minute exposures, the maturation rates of the COs exposed to PG, DMSO and EG were almost the same as those of the control groups; however, the rates of G group exposed for 15 and 30 minutes were significantly lower (p<0.05) than the control group. These groups were also found to have a decrease in the ATP content of COs and DOs during and after exposure for the same periods (p<0.05). In addition, although the ATP contents of the COs after exposure to EG for any period were the same as the controls, the ATP content of the DOs exposed to EG for any period were significantly lower (p<0.05) than those of the controls. When the ATP content of the COs and DOs of each CPA were compared, the DOs exposed to PG were found to have a significantly greater level (p<0.05) than DOs exposed to G for any duration. In addition, the ATP content of DOs exposed to PG for 30 min and removal was also higher (p<0.05) than when exposed to DMSO for the same period. These findings indicate that PG may be a useful CPA for the cryopreservation of immature porcine oocytes.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.8
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• pp.1140-1150
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• 2009

Forage diets provide good quality carcasses in sheep but very little is known in tropical goats. An experiment was designed with Creole male goats using grass-based systems to assess carcass yield, scores, cuts and composition. After weaning (84 d, 9.2 kg LW) two modes of forage feeding were compared with two replicates of each. Feeding groups were: PF for animals reared at pasture (n = 62) and IF when reared indoors (n = 60). Given that forage finishing will result in low ADG it appeared necessary to study different fattening lengths. The kids were equally divided into 4 groups: group A (n = 32), 4mo after weaning; group B (n = 32), 4mo after A; group C (n = 30), 3mo after B and group D (n = 28), 2mo after C. The animals grazed (in two sub-flocks) on irrigated tropical pastures managed in a rotational system (28 d of re-growth) at a mean stocking rate of 1,200 kg/ha/yr LW. The IF groups were reared in collective pens on a slatted floor (2 replicates of 7 or 8 kids each). They were fed the same stand of tropical grass (25% DM, 12% CP) as that of pasture that was cut daily and provided ad libitum. The ADG (-10%), the weights of omental fat (-60%) and fat in shoulder (-18%), the ultimate pH of carcass (-12%), the meat colour score (-24%), the ""parameter accounting for redness (12%) and the DM and lipid contents (-4%) were significantly lower (p<0.05) in PF than in IF, while the liver was heavier (+23%, p<0.05). Feeding conditions seemed to be similar, thus, differences could be related to gastrointestinal parasitism in the PF system and hypotheses are discussed. Increasing the fattening duration, resulted in significant difference (p<0.01) in many traits: the weights at slaughter and of carcass increased by 40% and 60% from groups A to D and consequently the weights of body compartments and carcass cuts (1.5 to 2.0 fold more). When the results were presented as percentage of empty body weight and carcass weight, these preliminary results (carcass weight 9kg and yield 53%, muscle proportion 70%) and qualitative parameters (low fat score 2/5, fat proportion 5%), seem to be a good incentive for the sector to develop a niche market to meet consumer lean meat expectations. The indoors system could be implemented where there was low availability of grazing areas or problems of dog attacks.

• Journal of Pharmaceutical Investigation
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• v.36 no.2
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• pp.89-95
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• 2006

A selective and sensitive reversed-phase HPLC method for the determination of pentoxifylline in human serum was developed, validated, and applied to the pharmacokinetic study of pentoxifylline. Pentoxifylline and internal standard, chloramphenicol, were extracted from the serum by liquid-liquid extraction with dichloromethane and analyzed on a Luna CI8(2) column with the mobile phase of acetonitrile-0.034 M phosphoric acid (25:75, v/v, adjusted to pH 4.0 with 10 M NaOH). Detection wavelength of 273 nm and flow rate of 0.8 mL/min were used. This method showed linear response over the concentration range of 10-500 ng/mL with correlation coefficients greater than 0.999. The lower limit of quantification using 0.5 mL of the serum was 10 ng/mL, which was sensitive enough for pharmacokinetic studies of pentoxifylline. The overall accuracy of the quality control samples ranged from 89.3 to 92.7% for pentoxifylline with overall precision (% C.V.) being 4.1-9.2%. The relative mean recovery of pentoxifylline for human serum was 105.8%. Stability (stock solution, short and long-term) studies showed that pentoxifylline was not stable during storage. But three freeze-thaw cycles and extracted serum samples were stable. This method showed good ruggedness (within 15% C.V.) and was successfully applied for the analysis of pentoxifylline in human serum samples for the pharmacokinetic studies of orally administered $Trental^{\circledR}$ tablet (400 mg pentoxifylline), demonstrating the suitability of the method.

• Journal of Microbiology and Biotechnology
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• v.26 no.4
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• pp.730-738
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• 2016

est19 is a gene from Bacillus sp. K91 that encodes a new esterase. A comparison of the amino acid sequence showed that Est19 has typical Ser-Gly-Asn-His (SGNH) family motifs and could be grouped into the SGNH hydrolase family. The Est19 protein was functionally cloned, and expressed and purified from Escherichia coli BL21(DE3). The enzyme activity was optimal at 60℃ and pH 9.0, and displayed esterase activity towards esters with short-chain acyl esters (C₂-C₆). A structural model of Est19 was constructed using phospholipase A1 from Streptomyces albidoflavus NA297 as a template. The structure showed an α/β-hydrolase fold and indicated the presence of the typical catalytic triad Ser49-Asp227-His230, which were further investigated by site-directed mutagenesis. To the best of our knowledge, Est19 is a new member of the SGNH hydrolase family identified from thermophiles, which may be applicable in the industrial production of semisynthetic β-lactam antibiotics after modification.