Seed Biology,Stand Characteristics,and Regeneration of Fraxinus rhynchophylla Hance

Fruit size and seed moisture content were measured and seed production and dispersal were monitored to understand the seed biology of the Korean ash (Fraxinus rhynchophylla Hance) in two Korean ash forests. A combination of four ground treatments and four crown closure levels were created in a natural forest to understand the site conditions needed for seedling emergence in natural stands and to determine practical regeneration methods for direct seeding. The seed size of Korean ash increased until late May and its moisture content decreased rapidly in early November. Prolific seed bearing occurred every 3 yr. The distance of seed dispersal by wind was about 30 m, but more than 90% of the seeds dispersed within 10 m from the seed trees. Twenty-five seed trees per hectare provided for successful natural regeneration. The seedling emergence in the natural stands was best with scarification treatment and 25～50% of crown closure.     

Changes in cyclooxygenase-2 immunoreactivity in the hippocampus in a model of streptozotocin-induced type 1 diabetic rats

In this study, we investigated diabetic stage dependent cyclooxygenase-2 (COX-2) immunoreactivity in the dentate gyrus in streptozotocin (STZ)-induced type 1 diabetic rats. The animals were sacrificed at 2, 3 and 4 weeks after STZ treatment. Blood glucose levels were increased after STZ treatment. COX-2 immunoreactivity in dentate gyrus was significantly increased in these regions 3 weeks after STZ treatment and restored to its basal level to 4 weeks after STZ treatment. In contrast, COX-2 immunoreactivity was not changed in CA3 region in all groups. These results suggest that STZ-induced type 1 diabetes transiently, but not permanently, decreased synaptic transmission and plasticity 3 weeks after STZ treatment in the dentate gyrus.     

Production of somatic chimera chicks by injection of bone marrow cells into recipient blastoderms

Several types of cells, including blastoderm cells, primordial germ cells, and embryonic germ cells were injected into early-stage recipient embryos to produce chimera avians and to gain insights into cell development. However, a limited number of studies of avian adult stem cells have also been conducted. This study is, to the best of our knowledge, the first to evaluate chicken bone marrow cells' (chBMC) ability to differentiate into multiple cell lineages and capability to generate chimera chicks. We induced random differentiation of chBMCs in vitro and injected immunologically selected pluripotent cells in chBMCs into the blastoderms of recipient eggs. The multipotency of BMCs from the barred Plymouth rock (BPR) was confirmed via AP staining, RT-PCR, immunocytochemistry, and FACS using specific markers, such as Oct-4 and SSEA-1, 3 and 4. Isolated chBMCs were found to be able to induce in vitro differentiation to multiple cell lineages. Approximately 5,000 chBMCs were injected into the blastoderms of white leghorn (WL) recipients and proved able to contribute to the generation of somatic chimera chicks with a frequency of 2.7% (2 of 73). Confirmation of chimerism in hatched chicks was achieved via PCR analysis using D-loop-specific primers of BPR and WL. Our study demonstrated the successful production of chimera chicks using chBMC. Therefore, we propose that the use of adult chBMCs may constitute a new possible approach to the production of chimera poultry, and may provide helpful studies in avian developmental biology.     

Analysis of population structure and genetic diversity in balloon flower (Platycodon grandiflorum (Jacq.) A. DC.) germplasm using Simple Sequence Repeat (SSR) markers

Balloon flower (Platycodon grandiflorum A. DC) is widely distributed in South Korea and there are some local landraces that are cultivated as a vegetable crop or medicinal plant. Making use of the gene resources of wild-type and landraces is a way to increase the genetic diversity of the cultivars. However, few tools or information are available on an efficient identification system for maintaining and management of these landraces. To improve the genetic resources for balloon flower, 22 simple sequence repeat (SSR) markers, also known as microsatellite markers, were evaluated in a collection of 42 balloon flower landraces, 34 of which were from Korea and eight from China. All microsatellite markers produced the 107 alleles ranging from 2 to 10 with a mean of 4.864 alleles per each locus (N_A). The values of observed heterozygosity (H_O) and expected heterozygosity (H_E) ranged from 0.00 to 0.667 (mean of 0.285) and from 0.024 to 0.741 (mean of 0.416), respectively. An average value of polymorphic information contents (PIC) were 0.382 with a range of 0.023 to 0.703. Results of population structure and phylogenetic and principal coordinate analysis (PCoA) indicated that P. grandiflorum germplasm formed two largely distinct clusters according to their origins and the genetic differentiation. There was a high level of genotypic diversity at broad geographic regions between Korea and China, but the low genetic differentiation was found within the collections from Korea. The results of the genetic diversity will be useful for the selection of the parents for developing balloon flower breeding and the multi-locus SSR markers developed herein will be a valuable resource for germplasm assessments, evaluation of genetic diversity, and population genetic studies of balloon flower.     

Recent research on bovine paratuberculosis in South Korea

Bovine paratuberculosis (Johne's disease), a chronic and debilitating disease of ruminants caused by Mycobacterium avium subspecies paratuberculosis (MAP), is a major cause of chronic ruminant enteritis. A national eradication program has been in place in South Korea since the first report of the disease in 1967; however, only limited data on bovine paratuberculosis in South Korea are available. Some research, such as investigations of the reactivity of animal sera against MAP antigens, has been done in localized areas and in limited animal species. Compared with the worldwide situation, the development of diagnostic methods in South Korea has shown similar results even though some data were obtained from international collaborative studies. MAP is considered by some to be zoonotic, noting an association with Crohn's disease, although this issue is still controversial; however, research into this association is limited. Decisions based on disease priorities have hampered active progress in research on the disease. In this paper, we reviewed the available results generated from South Korea compared with global research. Finally, we propose a theme for future research.     

Application of a solid-phase fluorescence immunoassay to determine oxytetracycline and tetracycline residues in tissue of olive flounder (Paralichthys olivaceus)

Parallux, a solid-phase fluorescence immunoassay (SPFIA) developed for antibotics residue detection in milk, was applied for analysis of fish tissue. The recommended therapeutic doses of oxytetracycline (OTC, 100 g/ton water, withdrawal period 30 days) and tetracycline (TC, 150 g/ton water, withdrawal period 30 days) were treated to a group of 35 olive flounders (Paralichthys olivaceus) using dipping administration. Muscle was sampled before and after drug treatment 1st, 2nd, 3rd, 5th, 7th, and 14th day. The concentration of oxytetracycline in muscle, determined by SPFIA, was compared with that of internal standard (100 ppb as oxytetracycline). The S/C ratio of sample inhibition value to cutoff inhibition value was employed as an index to determine the muscle residue in olive flounder. To investigate the recovery rate, and standard solutions were added to muscle samples to give final concentrations in muscle of 0.1 and 0.5 microg/ml. The recovery rates of all spiked samples were >89% of the spiked value. OTC and TC were detected in muscle of fishes treated until the 3rd day of withdrawal period. The present study showed that the SPFIA can be easily adopted in predicting tissue residues for OTC and TC in farmed fishes.     

Epidemiological characteristics and financial costs of the 1997 foot-and-mouth disease epidemic in Taiwan

Between March and July 1997, a devastating outbreak of foot-and-mouth disease (FMD), serotype O, occurred in pigs in Taiwan. A total of 6,147 pig farms with more than 4 million pigs were infected, and 37.7 per cent of the pigs in Taiwan either died (0.18 million pigs) or were killed (3.85 million pigs). The epidemic reached its peak during the fifth week after it was first recognised. During the eighth and ninth weeks, a two-dose blanket vaccination programme was instituted which led to a large reduction in new outbreaks. Except for two cities, the whole of Taiwan was declared an FMD-infected zone. During the four months in which new farm outbreaks occurred, 21.7 per cent of the pigs on infected farms showed clinical signs, and there was an overall mortality of 3.95 per cent. During the early stages of the epidemic, the incubation period was as short as 24 hours and the case fatality rates for suckling piglets reached 100 per cent. The financial cost of the epidemic was estimated at US$ 378.6 million, including indemnities, vaccines, carcase disposal plus environmental protection, miscellaneous expenses, and loss of market value. Owing to the ban on exports of pork to Japan, it is estimated that the total economic cost to Taiwan's pig industry will be about US$ 1.6 billion.