Jin Ae Lee

Application of seaweed cultivation to the bioremediation of nutrient-rich effluent

A seaweed biofilter/production system of being developed to reduce the environmental impact of marine fish farm effluent in coastal ecosystems as a part of an integrated aquaculture system. Several known seaweed taxa and their cultivars have been considered as candidate biofilter organisms based on their species-specific physiological properties such as nutrient uptake kinetics and their economic value. Porphyra is an excellent cadidate and shows efficient nutrient extraction properties. Rates of ammonium uptake were maintained at around 3 at 150 inorganic nitrogen at . Ulva is another possible biofilter candidate with an uptake rate of 1.9 under same conditions. A simple uptake/growth and harvest model was applied to estimate the efficiency of the biofilter/production system. The model was deterministic and used a compartment model structure based on difference equations. The efficiency of Porpyra filter was estimated over 17% of removal from the contimuous supply of 100 flow rate.

Effective molecular examination of eukaryotic plankton species diversity in environmental seawater using environmental PCR, PCR-RFLP, and sequencing

Phytoplankton are primary producers and can be important indicators of environmental change. To monitor the plankton species composition of environmental seawater samples, we developed a molecular method composed of colony polymerase chain reaction (PCR), polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP), and sequencing. A clone library of the ribosomal small subunit RNA gene (18S rDNA) in the nuclear genome was constructed by environmental PCR using a newly designed primer set and clones were directly amplified by colony PCR. To select unique putative clones, we choose a PCR-RFLP method that employed two restriction enzymes (MseI and Tsp509I). After the PCR-RFLP pattern was evaluated, selected clones were sequenced and analyzed. In this study, we revealed the hidden biodiversity in environmental seawater containing a wide range of taxonomic groups in the Alveolata (Ciliphora and Dinophyceae), Euglenozoa, Stramenopiles (Bacillariophyta), and Viridiplantae (Chlorophyta) without the need to conduct extensive colony isolation techniques. Moreover, we found species of fungi and Metazoa (Arthropoda, Annelida, and Mollusca). Therefore, this improved molecular method can be used to generate a robust database describing the species diversity of environmental samples and provide useful information regarding the dynamics of the eukaryotic plankton community structure.

Diversity and characteristics of terrestrial cyanobacteria near gimhae city, Korea

Cyanobacteria samples were collected from smears and mats growing on the surfaces of buildings, roadside walls, rocks, and monuments near Gimhae City, Korea. These populations were not as thick and dense, nor as diverse, as those found in temperate and tropical regions. Crusts at Gimhae City were dominated by colonial forms of species fromChroococcus, Aphanothece,Aphanocapsa, Gloeofthece,Gloeocapsa, andChroococidiopsis, as well as by filamentous forms from species ofScytonema andTolypothrix. The colonial forms appeared primarily as smears, especially for species ofGloeocapsa andChroococcidiopsis, whereas filamentous forms were the major constituents of mat populations. Invariably, the cells and trichomes of these colonial and filamentous forms were enclosed with a thick, firm, multi-colored laminar sheath, as seen by transmission electron microscopy. Such an association between cell walls and trichomes was stronger in the colonial forms, particularly forGloeocapsa, compared with the filamentous forms, in which the sheath did not detach from the wall even under arid conditions. The organization of cytoplasmic structures, particularly the thylakoid membranes, was least affected by acute dryness.

Utility of rbcS gene as a novel target DNA region for brown algal molecular systematics

The usefulness of molecular phylogenetic studies has increased remarkably as the quantity and quality of available DNA sequences has increased. When compared with the progress that has occurred in angiosperms and animals, there have been relatively few target DNA regions identified for use in taxonomic studies of brown algae. Therefore, in this study, we developed a new set of primers to amplify Rubisco small subunit (rbcS) gene sequences and determined the rbcS gene sequences of various species of brown algae including those belonging to Dictyotales, Ectocarpales, Fucales and Sphacelariales. The level of sequence variations in the rbcS gene varied according to the brown algal lineages. When focusing on the relationship of species within the genus Sargassum, the rbcS gene sequences provided useful information regarding the phylogenetic relationship among sections of the subgenus Bactrophycus. Based on the broad applicability and phylogenetic utility of the rbcS gene, we suggest that the sequence be used as a new target region for the molecular systematics of brown algae.

Metagenomic examination of diversity within eukaryotic plankton from the ulleung basin in the East Sea of Korea

We constructed planktonic 18S rDNA clone libraries for micro-organisms in the euphotic zone of the Ulleung Basin in the East Sea of Korea. They revealed the cryptic biodiversity of eukaryotic planktons and demonstrated specific phylogenetic affiliations at certain water depths. Dinoflagellate clones dominated at the surface and 75-m depth. Members of the Syndiniales order (Groups I and II), containing wellknown parasitic dinoflagellates, as well as one their prominent hosts, Polycystinea, were found exclusively at 75 m. These observations suggest that the presence of species from Groups I and II is closely related to the specific water mass. Therefore, their metagenomics information might be useful for delineating both water-mass and physico-chemical properties.