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- KOREAN
- P-ISSN2287-8327
- E-ISSN2288-1220
- SCOPUS, KCI
ISSN : 2287-8327
Vol.37 No.1
Abstract
To understand the effects of fluctuations in dam discharge due to river environments and phytoplankton communities,we monitored such environments and phytoplankton communities biweekly, from February 2001 to February 2002 andfrom February 2004 to February 2005, in the lower Han River (LHR), South Korea. The phytoplankton abundance duringthe dry season was approximately two times higher than that during the rainy season. In particular, fluctuations indiatom assemblages, which constituted over 70% of the total phytoplankton abundance, were affected severely by thechanges in the discharge. When a large quantity of water in a dam was discharged into the LHR, the conductivity and theconcentrations of total nitrogen (TN), total phosphorus (TP), and dissolved inorganic phosphorus (DIP) decreased rapidly,whereas the concentrations of suspended solids (SS), dissolved inorganic nitrogen (DIN), and dissolved silica (DSi)increased immediately. Time-delayed relationship also revealed that the dam discharge had an immediately significantnegative relationship with phytoplankton abundance. On the whole, fluctuations in phytoplankton communities in theLHR were influenced much more by hydrodynamics such as dam discharge than by the availability of nutrients. Thus, thevariability in these concentrations usually parallels the strength of river flow that is associated with summer rainfall, withhigher values during periods of high river discharge.
Abstract
The effect of different turnover time of water on the decomposition of emergent macrophyte litter (Zizania latifoliaGriseb.) was investigated using a microcosm experiment. Microcosm treatment represented different turnover time ofwater; 1, 2, 4 and 8 weeks. The litterbags from each treatment were retrieved every 2 weeks until the 8th week and thewater simultaneously sampled with the litterbag. The dry weight and the content of major cations in the litter, and thecontent of available N, P, and major cations in the water were analyzed. Dry weight loss after 8 weeks indicated the lowerdecay rates under the condition of short turnover time of water. Major cations from the litter and the water showed thatthe leached amounts of K and Mg from the litter were highest in the 2nd week and dramatically decreased from the 4thweek. The dynamics of available nitrogen and phosphorus in the water showed that as the water turnover time was gettinglonger, the amounts of available nitrogen and phosphorus remained higher. These results suggest that wetlands withlonger turnover time of water could maintain the increased nitrogen and phosphorus and no outflow of the nutrientscould cause eutrophication problem.
Abstract
Robinia pseudoacacia has become invasively naturalized in Japan. We investigated the role of sexual reproduction in thedevelopment of R. pseudoacacia riparian forests along the Chikumagawa River in Japan, by using five chloroplast (cpSSR)and seven nuclear (nSSR) markers. We identified eight chloroplast haplotypes and 147 nuclear genotypes from 619 R. pseudoacacia trees sampled in three plots (Plots A, B, and C) and along two line transects (Lines D and E). CpSSR analysesshowed that multiple maternal lines were distributed along the river, and that some haplotypes from different populationsoverlapped. In addition, while Plots A and B were separated by a short distance, only these two plots exhibitedgenetic differentiation in the haplotypes. In the nSSR analysis, all pairwise FST values among the three plots were significantlydifferent from zero. Kinship analysis based on nSSR markers revealed that kinship connected many individuals toanother individual from the same plot. These results indicate that seed dispersal near to mother trees contributes to thefine-scale genetic structure of R. pseudoacacia riparian forests. Our results indicate that sexual reproduction, in additionto asexual reproduction, is a major contributor to the fine-scale formation of R. pseudoacacia forests.
Abstract
The effectiveness of N-acetyl-L-cysteine (NAC) to protect blood cells against Mitomycin C (MMC) induced genotoxicitywas investigated in human chronic myeloid leukemia cells (KCL22) using the alkaline comet assay. The comet assay wasselected as sensitive and rapid method for analysis of DNA damage and repair in individual cells. NAC treatment alonedid not produce any damage in KCL22 cell. But NAC was found to be effective in reducing genotoxic damage in KCL22cells exposed to MMC. These results confirm the literature data that, given the safety and ability to reduce DNA damage. NAC may be useful to prevent drug-mediated genotoxicity.
Abstract
The phylogenetic analysis was carried out to find out the validity of Chrysochroa coreana as a new species. The insectspecimens were collected at Kaohsiung, Taiwan and Shizuoka, Japan. Partial region (532 bp) of COI was amplified andsequenced. The sequences were aligned and then analyzed. Based on the Kimura-2-parameter method, we calculatedgenetic distances among them. It indicated that the Korean individual of C. fulgidissima was closely related to Taiwan onewith relatively low genetic distance (0.083). On the other hand, the Japanese individual was remotely related with thoseof Korean (0.192) and Taiwan (0.183) individuals. To clarify if the populations of C. fulgidissima from Korea, Taiwan, andJapan are different at the level(s) of subspecies, species, or genus, it is necessary that more samples of the members of thefamily Buprestidae should be collected and genetically analyzed.