A survey of porcine reproductive and respiratory syndrome among wild boar populations in Korea

No information is currently available on porcine reproductive and respiratory syndrome virus (PRRSV) infection in wild boars (Sus scrofa) in Korea. In this study, the status of PRRS in wild boars was investigated. Blood samples were collected from 267 wild boars from eight provinces in Korea. Four of the samples tested (1.5%) were positive for PRRSV antibodies and eight (3.0%) were positive for antigens. Of the virus-positive samples, three and five samples were typed as containing European (EU, type 1) or North American (NA, type 2) viruses, respectively. Two amplicons (one from type 1 and one from type 2) were used to analyze the PRRSV open reading frame 7 (ORF7) sequence. The nucleotide sequences of type 1 PRRSV ORF7 had identities between 96.1% and 98.4% with PRRSVs from domestic pigs in Korea. The sequences of type 2 PRRSV ORF7 had identities of 100% with the PRRSV strain VR-2332, which was prototypic North American strain. These results show that PRRSVs are present in wild boars in Korea, and effective PRRSV surveillance of the wild boar population might therefore be useful for disease control.     

Preparation of bio-polyurethane using castor oil and antibacterial hybrid films thereof with silver-doped hydroxyapatite

The hybrid films of bio-polyurethane (Bio-PU) and silver-doped hydroxyapatite (HA-Ag) for breathable and antibacterial textile applications. The Bio-PU was synthesized using a mixture of castor oil based polyol with petroleum based poly(ethylene glycol). Silver doping to hydroxyapatite(HA) was carried out through ion exchange mechanism between calcium ion in HA and silver ion (Ag⁺) in aqueous solution of AgNO₃. The concentration of Ag⁺ was controlled to 100-300 ppm. The existence of silver in HA was proved using SEM-EDS while the silver doping amount was estimated by measuring residual concentration of Ag⁺ after doping using ICP-OES. It was found that the hybrid films exhibited excellent antibacterial activity against bacteria of S. aureus and K. pneumonia by showing 99.9 % reduction of bacteria.     

Measuring the Containment and Spillover Effects of Urban Growth Boundaries: The Case of the Portland Metropolitan Area

Although urban growth boundaries (UGBs) are increasingly used as a containment policy to promote contiguous and compact urban forms, little is known about how UGBs affect development within the designated area or how development is displaced to other cities. This study analyzes the UGB's containment and spillover effects, focusing on the case of the Portland metropolitan area where UGBs have long been implemented. This is accomplished by employing a spatial market disequilibrium framework in which explicit consideration is given to the containment and spillover processes when under the influences of UGBs. The findings suggest that UGBs can promote development within the boundaries, but that cooperation with neighboring municipalities is necessary to effectively attain the policy goals.     

Vibrio parahaemolyticus Associated with Mass Mortality of Postlarval Abalone,Haliotis diversicolor supertexta (L.), in Sanya,China

Outbreaks of mass mortality in postlarval abalone, Haliotis diversicolor supertexta (L.), have swept across south China since 2002 and in turn have resulted in many abalone farms closing. Twenty‐five representative bacterial isolates were isolated from a sample of five diseased postlarval abalone, taken 15 d postfertilization during an outbreak of postlarval disease in Sanya, Hainan Province, China in October 2004. A dominant isolate, referred to as Strain 6, was found to be highly virulent to postlarvae in an experimental challenge test, with a 50% lethal dose (LD₅₀) value of 3.2 × 10⁴ colony forming units (CFU)/mL, while six of the other isolates were weakly virulent with LD₅₀ values ranging from 1 × 10⁶ to 1 × 10⁷ CFU/mL, and the remaining 18 isolates were classified as avirulent with LD₅₀ values greater than 1 × 10⁸ CFU/mL. Using both an API 20E kit and 16S recombinant DNA sequence analysis, Strain 6 was shown to be Vibrio parahaemolyticus. It was sensitive to 4 and intermediately sensitive to 5 of the 16 antibiotics used when screening the antibiotic sensitivities of the bacterium. Extracellular products (ECPs) prepared from the bacterium were lethal to postlarvae when used in a toxicity test at a concentration of 3.77 mg protein/mL, and complete liquefaction of postlarvae tissues occurred within 24 h postexposure. Results from this study implicate V. parahaemolyticus as the pathogen involved in the disease outbreaks in postlarval abalone in Sanya and show that the ECPs may be involved in the pathogenesis of the disease.     

Population genetic structure of sea cucumber, Stichopus japonicus in Korea using microsatellite markers

Sea cucumber ( Stichopus japonicus ) is a commercially valuable species in Korea. We examined the genetic characteristics of sea cucumber populations in Korea using microsatellite markers. A total of 144 sea cucumbers from five populations were typed for nine polymorphic microsatellite loci. A total of 139 different alleles were found over all loci and many alleles were unique. The average number of allele per locus ranged from 6 to 18.4. The average observed and expected heterozygosities ranged from 0.532 to 0.626 and from 0.719 to 0.789 respectively. All populations showed significant departure from Hardy–Weinberg equilibrium at almost all loci except one (Psj2409). This deviation was in the direction of heterozygote deficit. A phylogenetic tree revealed two distinct clusters. One cluster was formed by the eastern sea population. A second cluster consisted of the subpopulations of the western and southern sea populations. The eastern sea population showed genetic differences such as a larger number of alleles per locus, a larger number of unique alleles and a smaller number of the most common alleles, suggesting a higher genetic diversity in this population. These results provide basic information on natural population genetic structure of S. japonicus in Korea.     

Visible light induced dextran-methacrylate hydrogel formation using (−)-riboflavin vitamin B2 as a photoinitiator and L-arginine as a co-initiator

The objective of this study is to examine the feasibility of using visible light to form gels from polysaccharide precursors. Hydrogel formation by visible light irradiation would be very beneficial because visible light is a benign light source and ready available when compared with other light sources such as UV. Dextran-methacylate was synthesized and photocrosslinked using (−)-riboflavin as a photoinitiator and L-arginine as a co-initiator under the visible light. The effect of various concentrations of (−)-riboflavin and L-arginine on the photo-crosslinking of dextran-methacrylate hydrogel was investigated. The fabricated hydrogel was characterized by FT-IR and SEM. The photoinitiator [(−)-riboflavin] and co-initiator (L-arginine) as well as dextran precursor are completely biocompatible. The optimum condition for the biocompatible dextran-based hydrogel formation under the harmless light source (visible light) was elucidated in this study. In general, the (−)-riboflavin, 0.01–0.5 %, and L-arginine, 5–20 % of the weight of dextran-methacrylate were the best condition in forming dextran-based hydrogels under the visible light. The three-dimensional hydrogel structure was verified by SEM morphology of swollen hydrogels. Photocrosslinking under the visible light source would enlarge the applications of this type of photocrosslinking in the biomedical area (e.g., eyes or other light-sensitive organs).     

The growth of disk abalone, Haliotis discus hannai at different culture densities in a pilot-scale recirculating aquaculture system with a baffled culture tank

The growth rate of disk abalone, Haliotis discus hannai, energy consumption and changes in water quality were monitored in a pilot-scale recirculating aquaculture system (RAS) for 155 days. Baffles were installed in the RAS culture tanks to enlarge the attachment area and clean out solid waste materials automatically by hydraulic force only. The experimental disk abalones, of shell length 24.5 ± 0.5 mm, were cultured at three stocking densities, 700, 1300 and 1910 individuals/m² bottom area, in triplicate. The abalones were fed with sea mustard, Undaria pinnatifida, once a week. The abalone feed conversion rates and daily growth rates ranged from 24.5 to 25.9 and 0.32 to 0.36%, respectively. Their daily shell increments and survival rates ranged from 67.7 to 78.6 μm/day and 87.6–92.2%, respectively. The growth in weight tended to decrease at a culture density of 1300 individuals/m² bottom area, while shell increments and survival rates were acceptable at this density. The total power consumption for heating was 1185.4 kW, comprising 30.2% of the total power consumption, while the average water exchange rate was only 2.9% per day. The total ammonia nitrogen stabilized below 0.07 mg/L, after conditioning of the biofilter. The NO₂⁻–N, NO₃⁻–N and total suspended solid concentrations were also maintained within acceptable ranges for the normal growth of disk abalone. The use of the RAS with these newly designed culture tanks for disk abalone culture produced 1300 individuals/m² bottom area with a water exchange rate of only 2.9% per day and used about one-tenth of the heat energy of a conventional flow-through system.     

Comparison of Various Kinds of Vegetative Indices for Chlorophyll Contents Using Low-Resolution Camera

Journal of Crop Science and Biotechnology - Nitrogen management is crucial for high yield potential of crops as well as reducing environmental pollution. However, the heterogeneity of nitrogen...