Se-Joo Kim

Electrorheological characterization of polyaniline dispersions

Suspensions of polyaniline in silicone oil have been investigated as potential candidates for dry-base electrorheological (ER) fluid systems. Polyaniline was synthesized by a chemical oxidation of aniline in an acidic media. Its optimum conductivity (in the semiconductive range) for ER purposes was achieved by adjusting the pH of an aqueous solution containing polyaniline particles. ER experiments were conducted with a Haake rheometer for steady shear experiments to investigate the effects of imposed electric fields, the polymerization temperature (molecular weight), and the dispersing oil on ER performance. ER properties of polyaniline suspensions were found to be improved by increasing both the imposed electric field and the polymerization temperature of the used polymer. Suspensions using kerosene also show greater ER effect than that using silicone oil because of the smaller dielectric constant of kerosene than that of silicone oil. A scaling law is introduced to analyse the ER data.

Taxonomic Redescriptions of Two Ciliates, Protogastrostyla pulchra n. g., n. comb. and Hemigastrostyla enigmatica (Ciliophora: Spirotrichea, Stichotrichia), with Phylogenetic Analyses Based on 18S and 28S rRNA Gene Sequences

ABSTRACT. The morphology and infraciliature of two stichotrichid ciliates, Gastrostyla pulchra (Perejaslawzewa 1886) Kahl, 1932 and Hemigastrostyla enigmatica (Dragesco and Dragesco‐Kernéis 1986) Song & Wilbert, 1997 , collected from marine and brackish sediments, were investigated by using living observations and protargol impregnations. Both 18S and 28S rRNA genes of these two species were sequenced. The 18S rDNA show high similarities (98.4%–99.7%) among populations of each species. There is about 94% similarity in 18S rDNA genes between G. pulchra and Gastrostyla steinii, the type species of the genus, which has been confirmed to be an oxytrichid by previous studies. In the phylogenetic trees of 18S, 28S, and combined 18S and 28S rDNA, both G. pulchra and H. enigmatica are consistently placed outside the well‐established oxytrichid clade. Based on our analyses and previous ontogenetic data, we conclude that these two species may represent some lower groups in the subclass Stichotrichia, and that G. pulchra should represent a new genus, Protogastrostyla n. g. This new genus, which is morphologically similar to Gastrostyla, differs in its morphogenesis: the apical part of the old AZM is retained combining with the newly built membranelles that develop from the proters oral primordium; the primary primordia of the dorsal kinety; and marginal primordia commence de novo without a definite contribution from the old structure.

An approach to analyses of periphytic ciliate communities for monitoring water quality using a modified artificial substrate in Korean coastal waters

Structural parameters of periphytic ciliate communities on a modified substrate were studied in Korean coastal waters during the period August-November 2007. In order to reduce the strong disturbances from tidal current and circulation in marine ecosystems, a modified slide method, named the polyurethane foam enveloped slide (PFES) system, was used to host ciliate communities. A total of 37 ciliate species, about half of which belong to the orders Hypotrichida and Cyrtophorida, were identified using living observation and silver impregnation method with this system. The sessile ciliates belonged to the orders Peritrichida and Suctorida, while the motile forms were represented primarily by the species of the orders Hypotrichida, Cyrtophorida and Pleurostomatida. The species diversity and evenness were significantly higher in the PFES system than those on the conventional slides (paired t-test: t = 2.384, 2.415; P < 0.05). Multivariate analysis revealed that the ciliate communities from both sampling systems had similar species composition, but represented significant differences in species distribution and temporal dynamics mainly due to the most dominant peritrich Zoothaminium duplicatum, which overly colonized the conventional slides. Results suggest that the PFES system is more effective than the conventional slide method for periphytic ciliate colonization with high species diversity, evenness and sensitive temporal dynamics mainly due to the reduction of disturbances from tidal current and circulation in marine ecosystems.

Establishment of a Self-Mating Mosquito Colony of Anopheles sinensis From Korea

ABSTRACT Many Korean entomologists have attempted to colonize Anopheles sinensis Korean strain, a primary malaria vector in Korea, previous efforts, however, were unsuccessful. Only a study that a successful colonization of An. sinensis Korean strain over 5 generations was recently reported. Recently we obtained a self‐mating colony from this mosquito strain. The original colony was established from progenies obtained from females collected from So‐Rae District, Incheon, Republic of Korea (ROK), and was maintained for 23 successive generations. While the adult females of first five generations were fed on humans as a source of blood, those of the subsequent 18 generations were fed on white rats as a source of blood. A self‐mating colony was initiated from the 9th generation by rearing 200 and 300 newly emerged females and males, respectively, in a 30x30x30 cm cage. The insemination rates increased from approximately 40% to 81% by the 20th generation. Comparisons of biological aspects between artificial mating and self‐mating colonies are reported.

The mitochondrial genomes of Cambaroides similis and Procambarus clarkii (Decapoda: Astacidea: Cambaridae): the phylogenetic implications for Reptantia

Kim, S., Park, M.‐H., Jung, J.‐H., Ahn, D.‐H., Sultana, T., Kim, S., Park, J.‐K., Choi, H.‐G. & Min, G.‐S. (2012). The mitochondrial genomes of Cambaroides similis and Procambarus clarkii (Decapoda: Astacidea: Cambaridae): the phylogenetic implications for Reptantia. —Zoologica Scripta, 41, 281–292.

Viscoelasticity of an electrorheological fluid using a vertical oscillation rheometer

Abstract A vertical oscillation rheometer (VOR), which is designed for the purpose of electrorheological (ER) fluid measurements, is investigated. Linear viscoelastic material functions, such as complex viscosity, complex shear modulus, and loss tangent, are obtained in terms of the geometric parameters of the VOR, the measured force, and the applied strain. The VOR is then calibrated with a Physica rheometer using a corn starch-polybutene/kerosene ER fluid system. The geometry which oscillates vertically is found to be easily constructed and to measure the viscoelastic properties of the ER fluid with a high electric voltage generator. Data from the VOR are found to be reliable in a wide range of strain or frequency.

Nonreproductive Isolation Among Four Allopatric Strains of Anopheles sinensis in Asia

ABSTRACT To verify the genetic proximity of Anopheles sinensis strains in Korea, China, Japan, and Thailand, we established 5 iso-female lines, and investigated their genetic relationships by analyzing crossing tests and comparing the DNA sequences of rDNA internal transcribed spacer 2 (ITS2) and mitochondrial cytochrome c oxidase subunit 2 (CO2). The results of reciprocal and F1-hybrid crosses between Thailand Form B (X, Y2) with Japanese Form A (X, Y1), Japanese Form B with Korean Form B, and Korean Form B with Chinese Form B indicated that these strains were genetically compatible, providing viable progenies and completely synaptic polytene chromosomes. The sequences of ITS2 and CO2 among 10 Asian An. sinensis strains were almost identical to each other, and the sequence variation was very low (<0.6% in both regions). Based on the above results, it was confidently concluded that An. sinensis is a single cosmopolitan species even though its geographical distribution ranges are comparatively wide (>2,000 mi) and that the malaria-vector abilities of the various strains may vary depending on their geographical origins.

Development of single-nucleotide polymorphism-based phylum-specific PCR amplification technique: Application to the community analysis using ciliates as a reference organism

Despite recent advance in mass sequencing technologies such as pyrosequencing, assessment of culture-independent microbial eukaryote community structures using universal primers remains very difficult due to the tremendous richness and complexity of organisms in these communities. Use of a specific PCR marker targeting a particular group would provide enhanced sensitivity and more in-depth evaluation of microbial eukaryote communities compared to what can be achieved with universal primers. We discovered that many phylum- or groupspecific single-nucleotide polymorphisms (SNPs) exist in small subunit ribosomal RNA (SSU rRNA) genes from diverse eukaryote groups. By applying this discovery to a known simple allele-discriminating (SAP) PCR method, we developed a technique that enables the identification of organisms belonging to a specific higher taxonomic group (or phylum) among diverse types of eukaryotes. We performed an assay using two complementary methods, pyrosequencing and clone library screening. In doing this, specificities for the group (ciliates) targeted in this study in bulked environmental samples were 94.6% for the clone library and 99.2% for pyrosequencing, respectively. In particular, our novel technique showed high selectivity for rare species, a feature that may be more important than the ability to identify quantitatively predominant species in community structure analyses. Additionally, our data revealed that a target-specific library (or ciliate-specific one for the present study) can better explain the ecological features of a sampling locality than a universal library.

Mitochondrial genome of the hydrothermal vent shrimp Nautilocaris saintlaurentae (Crustacea: Caridea: Alvinocarididae)

Abstract We determined the mitochondrial genome (mitogenome) of Nautilocaris saintlaurentae, sampled at vent fields of the Tofua Arc in the southwestern Pacific. The genome was 15,928 bp in length and had the typical mitogenome structure of the infraorder Caridea. Its protein-coding genes were very similar to other alvinocaridid species in respect to length, AT content, and start and stop codons. However, N. saintlaurentae showed a 17.4--19.2% divergence in the nucleotide sequence from other alvinocaridid species. This information will be helpful in understanding the genetic relationship among members of the alvinocaridid shrimps.

Single-cell PCR on protargol-impregnated euplotid ciliates: a combined approach of morphological and molecular taxonomy

Ciliates are considered one of the most diverse protozoa and play significant roles in ecology. For successful taxonomic study of these microscopic eukaryotes, a staining procedure is necessary, due mainly to intrinsic difficulties in recognizing characteristics from living cells. Although molecular taxonomy has been used to resolve the ambiguities associated with traditional morphology-based taxonomy, extraction of genomic DNA from stained ciliate cells is not available yet. In the present study, we describe a method to extract genomic DNA from a single protargol-impregnated euplotid cell. By using HgCl2 as a fixative and modulating the exposure time of bleach solution in the protargol impregnation, high-quality genomic DNA can successfully be extracted from a stained single cell with minimal loss of morphological integrity. This technique will contribute to the effectiveness of combined approaches of molecular and morphological taxonomy from single ciliate cells.