• Journal of fish pathology
• /
• v.34 no.1
• /
• pp.71-80
• /
• 2021

Cephalexin, a semi-synthetic cephalosporin antibiotic, has long been used in fish aquaculture in various countries under legal authorization. The drug is thus widely available for use in other aquatic species except fishes like the crustacean whiteleg shrimp. This study aims to develop a sensitive method for laboratory residue studies to adopt in withdrawal period determinations. Through repeated trials from the existing methods developed for other food animal tissues, it was possible to achieve a sensitive high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method. The results showed that at a concentration of 0.1 mg/kg, the recovery rate was 81.79%, and C.V. value was 8.2%, which meet the recovery rate and C.V. recommended by Codex guideline. After satisfactory validation of analytical procedures, applicability to the shrimp tissue was confirmed in experimentally cephalexin-treated whiteleg shrimp. As a result, most muscle samples were detected below the limit of quantification (0.05 mg/kg) after day 3, and most hepatopancreas samples were detected below the limit of quantification after day 14. In particular, the limit of quantification 0.05 ppm with the presently developed method suggests sufficient sensitive over the current legal maximum residue limit of 0.2 mg/kg set for fishes.

• Journal of Microbiology and Biotechnology
• /
• v.17 no.8
• /
• pp.1242-1248
• /
• 2007

Genomic analysis of a hyperthermophilic archaeon, Thermococcus onnurineus NA1 [1], revealed the presence of an open reading frame consisting of 1,377 bp similar to ${\alpha}$-amylases from Thermococcales, encoding a 458-residue polypeptide containing a putative 25-residue signal peptide. The mature form of the ${\alpha}$-amylase was cloned and the recombinant enzyme was characterized. The optimum activity of the enzyme occurred at $80^{\circ}C$ and pH 5.5. The enzyme showed a liquefying activity, hydrolyzing maltooligosaccharides, amylopectin, and starch to produce mainly maltose (G2) to maltoheptaose (G7), but not pullulan and cyclodextrin. Surprisingly, the enzyme was not highly thermostable, with half-life ($t_{1/2}$) values of 10 min at $90^{\circ}C$, despite the high similarity to ${\alpha}$-amylases from Pyrococcus. Factors affecting the thermostability were considered to enhance the thermo stability. The presence of $Ca^{2+}$ seemed to be critical, significantly changing $t_{1/2}$ at $90^{\circ}C$ to 153 min by the addition of 0.5 mM $Ca^{2+}$. On the other hand, the thermostability was not enhanced by the addition of $Zn^{2+}$ or other divalent metals, irrespective of the concentration. The mutagenetic study showed that the recovery of zinc-binding residues (His175 and Cys189) enhanced the thermo stability, indicating that the residues involved in metal binding is very critical for the thermostability.

• Journal of Applied Biological Chemistry
• /
• v.50 no.1
• /
• pp.22-28
• /
• 2007

Most of the uplands in alpine regions during off-season are left as bare soil and thus vulnerable to severe erosion due to the inherent topographical conditions. Appropriate management strategy to cope with this problem is urgently needed, yet few researches have been reported on the effects of winter cover crop and management on soil erosion. We assessed effects of ryegrass (Lolium multiflorum) as cover crop, green manure or mulching residue on soil erosion and quality through field and segment plot lysimeter experiments in alpine uplands. Ryegrass successfully adopted to winter in alpine region based on biomass, nutrient contents, and vigors of top and root systems. Incorporation of ryegrass into soil maintained soil fertility, nutrient uptake, and yield of cabbage exerting potential use as green manure. Cultivation of ryegrass suppressed occurrence of Chinese cabbage pests. Surface coverage by ryegrass as cover crop and mulching residue significantly reduced soil loss up to 96%, when combined with soil conservation management practices. Results revealed maintaining cover crop over winter was beneficial in reducing soil erosion, and sustaining soil quality and Chinese cabbage productivity. This study suggested winter cover crop, followed by green manure and mulching, and conservation tillage system could be one of the best management practices in alpine sloping uplands cultivating Chinese cabbage.

• Korean Journal of Soil Science and Fertilizer
• /
• v.46 no.6
• /
• pp.510-518
• /
• 2013

Corn was mainly cultivated in slope land during summer season when heavy rain falls so that soil loss occurs severely. Especially, soil disturbance and exposure of topsoil by conventional tillage intensifies soil loss by heavy rain. The aim of this study was to develop surface covering and tillage methods for reducing soil loss in corn cultivation. The experiment was conducted in 17% sloped lysimeter with 8 treatments including strip tillage after surface covering with rye residue, strip tillage after residue covering of several crops and sod culture, black polyethylene film covering after conventional tillage and control. Amount of runoff water and eroded soil, and corn growth were investigated. Amounts of runoff water in all plots except black polyethylene plot ranged from 152 to 375 $m^3\;ha^{-1}$, accounting for 13~32% of 1,158 $m^3\;ha^{-1}$ in control. Amount of eroded soil decreased by 94 to 99% (3 to 89 kg $ha^{-1}$) in plots of strip tillage after covering with crop residues compared to control with 1,739 kg $ha^{-1}$. Corn yields in plots of strip tillage after covering with crop residues ranged from 6.0 to 6.9 Mg $ha^{-1}$, while that of control was 6.5 Mg $ha^{-1}$. The results suggest that strip tillage methods after surface covering with crop residues are very effective on soil conservation of slope land in corn cultivation.

• Korean Journal of Soil Science and Fertilizer
• /
• v.47 no.2
• /
• pp.120-126
• /
• 2014

An accurate analysis of nutrient balance in different cropping systems is necessary for improving soil fertilities, causing higher crop yields and quality. This study was carried out to investigate the nutrient balance, changes in soil properties, and their effects on crop yield in long-term field cultivation under mono- and rotation-cropping systems (MCS and RCS, respectively). The analytical results of the soil properties showed that the application of mineral fertilizers alone in the MCS leads the reduction of soil CEC, exchangeable Ca, and microbial biomass C and N. Compared with the MCS of soybean, the RCS of soybean and barley significantly improved the soil properties, which increased crop yield. It might be due to the barley residue added to the RCS soil. Mean nutrient balances for 4 years were -55.9 kg N, +34.7 kg $P_2O_5$, and -0.3 kg $K_2O$ $ha^{-1}$ for the MCS and +19.7 kg N, +107.4 kg $P_2O_5$, and -48.6 kg $K_2O$ $ha^{-1}$ for the RCS, respectively. These nutrient imbalances mean that conventional fertilizer recommendations were inadequate for maintaining soil nutrient balance. From these results, we can conclude that the crop rotation may change comprehensive physical, chemical, and biological soil properties. These changes could affect the nutrient balance and then the crop yield.

• Korean Journal of Environmental Agriculture
• /
• v.34 no.2
• /
• pp.111-119
• /
• 2015

BACKGROUND: Ethychlozate (ECZ) is a plant growth regulator of synthetic auxin for agricultural commodities (ACs). Accurate and sensitive method to determine ECZ in diverse ACs on global official purpose is required to legal residue regulation. As the current official method is confined to the limited type of crops with poor validation, this study was conducted to improve and extend the ECZ method using high-performance liquid chromatography (HPLC) in all the registered crops with method verification. METHODS AND RESULTS: ECZ and its acidic metabolite (ECZA) were both extracted from acidified samples with acetone and briefly purified by dichloromethane partition. ECZ was hydrolyzed to form ECZA and the combined ECZA was finally purified by ion-associated partition including hexane-washing. The instrumental quantitation was performed using HPLC/ FLD under ion-suppression of ECZA with no interference by sample co-extractives. The average recoveries of intra- and inter-day experiment ranged from 82.0 to 105.2% and 81.7 to 102.8%, respectively. The repeatability and reproducibility for intra- and inter-day measurements expressed as a relative standard deviation was less than 8.7% and 7.4%, respectively. CONCLUSION: Established analytical method for ECZ residue in ACs was applicable to the nation-wide pesticide residues monitoring program with the acceptable level of sensitivity, repeatability and reproducibility.

• Animal cells and systems
• /
• v.15 no.4
• /
• pp.310-314
• /
• 2011

The Banna miniature pig (BNMP) is a representative miniature pig breed in China. Even though BNMP dwarfism is obvious, its underlying causative mutations remain unknown. In this study, the BNMP and Large White pig (LWP) serum growth hormone (GH) and insulin-like growth factor (IGF-1) levels were detected by ELISA and compared. BNMP serum IGF-1 levels were significantly lower than LWP levels (P<0.05). The miniature condition may arise from mutations in the GH and GH receptor (GHR) genes. Therefore, GH and GHR cDNA from the BNMP were cloned into a pMD18-T vector by RT-PCR using the total RNA obtained from the BNMP's pituitary and liver tissues. Sequencing results indicated that the open reading frame of the BNMP GH gene is composed of a 26-residue signal peptide and a 191-residue mature peptide. The coding sequence of the BNMP GHR gene contained 639 amino acids, including a signal peptide that is 18 amino acids long. Two amino acid substitutions, A09V and R22Q, were found in the signal peptide of the GH gene. Additionally, the S104P mutation was found in the BNMP's mature GH protein. Four mutations in the cytoplasmic domain of GHR may influence the downstream signal transduction of GHR, which needs further experimental evidence.

• Asian-Australasian Journal of Animal Sciences
• /
• v.16 no.4
• /
• pp.529-533
• /
• 2003

The intake, dry matter (DM) digestibility, total mean retention time (TMRT) and weight changes were investigated in four fat tailed and four Dorper sheep fed on a maize stover crop residue. Animals were subjected to five dietary treatments, which were: 90, 135 and $180g\;DM/kgBW^{0.75}/day$ of chopped maize stover offered with urea, and in subsequent dietary treatments $180g\;DM/kgBW^{0.75}/day$ of stover supplemented with either dried bean husks or poultry manure. Although not statistically different (p>0.05) fat tailed sheep had higher maize stover intake than the Dorper sheep when expressed per metabolic body weight. The DM intake and digestibility increased significantly (p<0.001) in both sheep breeds when the maize stover offer levels were increased from 90 to $135g/kgBW^{0.75}/day$. Dorper sheep had significantly (p<0.001) higher DM digestibility and longer total mean retention times for both the liquid and solid matter than the fat-tailed sheep. Fat-tailed sheep gained 4.75 kg while Dorper sheep gained 3.75 kg over the entire experimental period. The weight change per dietary treatment was affected by the amount of maize stover and the type and amount of supplement consumed. The higher DM digestibility and longer total mean retention time in Dorper sheep shows that the breed has adapted to utilize the low quality roughage diets. An indigenous fat tailed, has the potential to ingest high volumes of fibrous feed and has higher voluntary intakes relative to its body size. The two sheep breeds are a valuable genetic resource in sub Saharan Africa that is characterized by long dry season with no readily available and affordable conventional feeds for small ruminants.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.38 no.2
• /
• pp.74-83
• /
• 2018

The objectives of this study was to evaluate the degradability and digestibility of crude protein (CP), rumen undegradable protein (RUP), and individual amino acids (AA) on six by-product feedstuffs (BPF) (rice bran, RB; wheat bran, WB; corn gluten feed, CGF; tofu residue, TR; spent mushroom substrate from Pleurotus ostreatus, SMSP; brewers grain, BG) as ruminants feed. Three Hanwoo steers (40 months old, $520{\pm}20.20kg$ of body weight) fitted with a permanent rumen cannula and T-shaped duodenal cannula were used to examine of the BPF using in situ nylon bag and mobile bag technique. The bran CGF (19.2%) and food-processing residue BG (19.7%) had the highest CP contents than other feeds. The RUP value of bran RB (39.7%) and food-processing residues SMSP (81.1%) were higher than other feeds. The intestinal digestion of CP was higher in bran RB (44.2%) and food-processing residues BG (40.5%) than other feeds. In addition, intestinal digestion of Met was higher in bran RB (55.7%) and food-processing residues BG (44.0%) than other feeds. Overall, these results suggest that RB and BG might be useful as main raw ingredients in feed for ruminants. Our results can be used as baseline data for ruminant ration formulation.

• BMB Reports
• /
• v.40 no.2
• /
• pp.239-246
• /
• 2007

Riboflavin synthase from Escherichia coli is a homotrimer of 23.4 kDa subunits and catalyzes the formation of one molecule each of riboflavin and 5-amino-6-ribitylamino- 2,4(1H,3H)-pyrimidinedione by the transfer of a 4-carbon moiety between two molecules of the substrate, 6,7- dimethyl-8-ribityllumazine. Each subunit comprises two closely similar folding domains. Recombinant expression of the N-terminal domain is known to provide a $C_2$-symmetric homodimer. In this study, the binding properties of wild type as well as two mutated proteins of N-terminal domain of riboflavin synthase with various ligands were tested. The replacement of the amino acid residue A43, located in the second shell of riboflavin synthase active center, in the recombinant N-terminal domain dimer reduces the affinity for 6,7-dimethyl-8-ribityllumazine. The mutation of the amino acid residue C48 forming part of activity cavity of the enzyme causes significant $^{19}F$ NMR chemical shift modulation of trifluoromethyl derivatives of 6,7-dimethyl-8-ribityllumazine in complex with the protein, while substitution of A43 results in smaller chemical shift changes.