• KSBB Journal
• /
• v.26 no.3
• /
• pp.206-210
• /
• 2011

The growth effect of Nannochloropsis oculata (N.oculata), unicellular microalgae, by alginate was investigated. Alginate was depolymerized with sulfuric acid ($H_2SO_4$) and heat ($121^{\circ}C$), simultaneously. Addition of 0.75% alginate oligomer depolymerized with 0.2 N $H_2SO_4$ showed the maximum yield and the growth rate of N. oculata. Chlorophyll content and reducing sugar was increased by alginate oligomer in a dose-dependent manner. Alginate oligomer promoted the growth of N. oculata, whereas the original alginate polysaccharides had no significant effect. Laminaria japonica (L. japonica) extract containing high level of alginate was also increased growth rate and chlorophyll content. $CO_2$ supply addition to L. japonica extract showed no change the growth rate, although addition to alginate oligomer showed prominently increased. N. oculata could use more saccharides in presence of $CO_2$ according to reducing sugar determination. From these results, it is useful to establish optimal condition for high cell density cultivation of N. oculata.

• Journal of Microbiology and Biotechnology
• /
• v.19 no.8
• /
• pp.792-802
• /
• 2009

Antimicrobial peptides (AMPs) are considered to be a promising alternative to conventional antibiotics for future generations. We identified four novel hexapeptides with antimicrobial activity: KCM11 (TWWRWW-$NH_2$), KCM12 (KWRWlW-$NH_2$), KCM21 (KWWWRW-$NH_2$), and KRS22 (WRWFIH-$NH_2$), through positional scanning of a synthetic peptide combinatorial library (PS-SCL). The ability of these peptides to inhibit the growth of a variety of bacteria and unicellular fungi was evaluated. KCM11 and KRS22 preferentially inhibited the normal growth of fungal strains, whereas KCM12 and KCM21 were more active against bacterial strains. Bactericidal activity was addressed in a clear zone assay against phytopathogenic bacteria, including Pectobacterium spp., Xanthomonas spp., Pseudomonas spp., etc. KCM21 showed the highest activity and was effective against a wide range of target organisms. Application of KCM21 with inoculation of Pectobacterium carotovorum subsp. carotovorum on detached cabbage leaves resulted in an immune phenotype or a significant reduction in symptom development, depending on the peptide concentration. Cytotoxicity of the four hexapeptides was evaluated in mouse and human epithelial cell lines using an MTT test. The results revealed a lack of cytotoxic effects.

• Animal cells and systems
• /
• v.11 no.2
• /
• pp.183-189
• /
• 2007

To investigate the properties of mucosubstances of the epidermis in various teleostean species, conventional histochemical stainings were used on the skin in five species of order Perciformes, i. e., yellowtail, Seriota quinqueradiat, striped beakperch, Oplegnathus fasciatus, brown spotted grouper, Epinephelus chlorostigma, sea chub, Ditrema temmincki and multicolorfin rainbowfish, Halichoeres poecilopterus. The following methods were used: periodic acid Schiff (PAS), alcian blue (AB) pH at 2.5, AB pH at 1.0, AB pH at 2.5-PAS, AB pH at 1.0-PAS, aldehyde fuchsin (AF) pH at 1.7-AB pH at 2.5 and high iron diamine (HID)-AB pH at 2.5. The epidermis of all five species consisted of three layers: superficial, middle, and basal layer. The superficial layer was comprised of rather flattened cells. In particular, the outermost layer of striped beakperch and middle layer of sea chub consisted of mucus-secreting cells. Mucous cells, the unicellular glands, were found in epidermis but varied in number in different body regions and species. Although there was a slight difference in the amount in various species and body regions, the secretory contents of the mucous cells in the five teleostean species contained acidic mucopolysaccharides. In yellowtail, striped beakperch, and multicolorfin rainbowfish, the property of mucosubstances was identified as sialomucin, while it was sulphomucin in brown spotted grouper and sea chub.

• Journal of Plant Biology
• /
• v.38 no.3
• /
• pp.243-250
• /
• 1995

Involvement of calcium in signal transduction of salt stress was investigated in 1.7 M NaCl adapted Dunaliella salina, extremely halotolerant, unicellular green alga. When hyperosmotic (3.4 M NaCl) or Hypoosmotic (0.8 M NaCl) stress was treated, extracellular calcium was influxed in or intracellular calcium effluxed from D. salina, respectively, and these fluxes were proportional to the degree of stress. This might indicate indirectly that the change of calcium level occurred within the cells. In addition, the change of calcium flux was ahead of glycerol synthesis which has been known as the physiological response to salt stress. Osmoregulation was affected byextracellular calcium concentration, and increase of glycerol content as an osmoticum was inhibited about 50% by treatment of TFP and W-7 known as calmodulin specific inhibitors. Furthermore, in the case of the hyperosmotic stressed cells, the amount of 21 kD and 39 kD protein appeared to be calcium binding protein were increased. Among these, the 39 kD protein was detected only in the hyperosmotic stressed cells. The results obtained in the present work suggest that the possibility of calcium as a second messenger in the transduction of salt stress signal exists in the osmoregulation system of D. salina.

• Applied Microscopy
• /
• v.37 no.4
• /
• pp.289-295
• /
• 2007

The genus Daldinia is a member of the Xylariaceae that has brown to dark brown and phaseoliform single cell ascospores with a conspicuous full germ slit. The isolate of D. childiae collected from Mt. Deuk-yu in Korea were compared with similar taxa, D. eschscholzii and D. concentrica.. Ascospores were $11{\sim}13{\mu}m{\times}5.5{\sim}6{\mu}m$ in size, light brown to brown, unicellular, ellipsoid-inequilateral, with dull round ends. Ascospore showed very faint ornamentation at ${\times}7.0k$ magnification. It is one of the main morphological characteristic Korean collection of D. childiae under SEM level and a main reason of reinterpretation of D. concentrica in Korea. Using KOH-extractable pigment color of stroma, D. concentrica that also has supported the SEM level investigation. Daldinia concentrica, having those characteristic recorded in Korea, should be renamed as D. childiae. However, the isolate will be the first record as D. childiae, having precise morphological description in Korea.

• Applied Microscopy
• /
• v.43 no.2
• /
• pp.47-53
• /
• 2013

The trichomes on leaves of three species of Mentha such as M. spicata, M. suaveolens, and M. piperita var were examined by scanning electron microscopy. Simple non-glandular trichomes and peltate glandular trichomes were distinctively occurred on these leaves. In M. spicata, short and sharp non-glandular trichomes were dominantly appeared on adaxial surface, whereas capitate glandular trichomes were commonly localized on abaxial surface. In M. suaveolens, non-glandular trichomes were identified with simple unbranched and branched. Unbranched trichomes which were sharp and pointed in shape occurred on adaxial surface, however, branched and v-shaped trichomes appeared abundantly on abaxial surface. Peltate trichomes consisted of a large eight-celled head. Small capitates trichomes consisted of a cylindrical head with an one-celled uniseriate stalk. In M. piperita var, single non-glandular trichomes and peltate trichomes were present on adaxial surface. Small capitate trichomes consisted of a globose unicellular head with a two- or three-celled uniseriate stalk. Peltate trichomes were distinctly present on abaxial surface, whereas they were not observed on adaxial surface. The trichomes were less dense in this species. Peltate trichomes consisted of a large eight-celled head, with an enlarged secretory cavity, attached to an one-celled short stalk.

• The Plant Pathology Journal
• /
• v.21 no.1
• /
• pp.13-20
• /
• 2005

Chlorella viruses are large icosahedral, plaque-forming, dsDNA viruses that infect certain unicellular, chlorellalike green algae. The genomic DNA of over 300 kb contains many useful genes and promoters. Over 40 chlorella viruses have been isolated from fresh water in Korea since 1998. The viruses were amplified initially in chlorella strain NC64A, and pure isolates were obtained by repeated plaque isolation. SDS-PAGE analysis revealed similar but distinct protein patterns, both among the group of purified viruses and in comparison with the prototype chlorella virus PBCV-1. Digestions of the 330- to 350-kb genomic DNAs with 10 restriction enzymes revealed different restriction fragment patterns among the isolates. The tRNA-coding regions of 8 chlorella viruses were cloned and sequenced. These viruses contain 14-16 tRNA genes within a 1.2- to 2-kb region, except for the SS-1 isolate, which has a 1039-bp spacer in a cluster of 11 tRNA genes. Promoter regions of several early genes were isolated and their activities were analyzed in transformed chlorella. Some promoters showed stronger activity than commonly used CaMV 35S promoter and chlorella transformation vectors for heterologous protein are beings constructed using these promoters.

• ALGAE
• /
• v.21 no.4
• /
• pp.407-416
• /
• 2006

Low molecular weight carbohydrates, phycobilin pigments and cell structure using light and transmission electron microscopy were used to describe a new genus of unicellular red algae, Erythrolobus coxiae (Porphyridiales, Porphyrideophyceae, Rhodophyta). The nucleus of Erythrolobus is located at the cell periphery and the pyrenoid, enclosed by a cytoplasmic starch sheath, is in the cell center. The pyrenoid matrix contains branched tubular thylakoids and four or more chloroplast lobes extend from the pyrenoid along the cell periphery. A peripheral encircling thylakoid is absent. The Golgi apparatus faces outward at the cell periphery and is always associated with a mitochondrion. Porphyridium and Flintiella, the other members of the Porphyrideophyceae, also lack a peripheral encircling thylakoid and have an ER-mitochondria-Golgi association. The low molecular weight carbohydrates digeneaside and floridoside are present, unlike both Porphyridium and Flintiella, which have only floridoside. The phycobilin pigments B-phycoerythrin, R-phycocyanin and allophycocyanin are present, similar to Porphyridium purpureum. The cells have a slow gliding motility without changing shape and do not require substrate contact. The ultrastructural features are unique to members of the Porphyrideophyceae and recent molecular analyses clearly establish the validity of this new red algal class and the genus Erythrolobus.

• BMB Reports
• /
• v.46 no.12
• /
• pp.575-581
• /
• 2013

Lipid droplet (LD) is a cellular organelle that stores neutral lipids as a source of energy and carbon. However, recent research has emerged that the organelle is involved in lipid synthesis, transportation, and metabolism, as well as mediating cellular protein storage and degradation. With the exception of multi-cellular organisms, some unicellular microorganisms have been observed to contain LDs. The organelle has been isolated and characterized from numerous organisms. Triacylglycerol (TAG) accumulation in LDs can be in excess of 50% of the dry weight in some microorganisms, and a maximum of 87% in some instances. These microorganisms include eukaryotes such as yeast and green algae as well as prokaryotes such as bacteria. Some organisms obtain carbon from $CO_2$ via photosynthesis, while the majority utilizes carbon from various types of biomass. Therefore, high TAG content generated by utilizing waste or cheap biomass, coupled with an efficient conversion rate, present these organisms as bio-tech 'factories' to produce biodiesel. This review summarizes LD research in these organisms and provides useful information for further LD biological research and microorganism biodiesel development.

• Fisheries and Aquatic Sciences
• /
• v.11 no.3
• /
• pp.149-158
• /
• 2008

Labyrinthulids are unicellular heterotrophic marine microalgae. Two labyrinthulid strains, L4 and L75, which produce generous amounts of polyunsaturated fatty acids(PUFAs), were isolated from leaves floating in the coastal areas of Quang Ninh province, Vietnam, and Fukuoka Prefecture, Japan, respectively. Both strains had spindle-shaped cells surrounded by ectoplasmic networks. Numerous oil bodies were observed in each cell, mostly in the vicinity of cell membranes. When soybean oil or soybean lecithin was used as a carbon source with peptone as a nitrogen source, the proportion of PUFAs reached 25-30% and 50-56% for L4 and L75, respectively. After 14 days of growth at $25^{\circ}C$, L4 produced 0.3 mg PUFAs/g-agar in PYA-SBO medium and 0.6 mg PUFAs/g-agar in PYA-SBL medium. In comparison, L75 produced 0.2 mg PUFAs/g-agar in both types of media. The differences between the two strains included changes in cellular morphology and the capacity for attaching tightly to fibers when cultured in liquid PYA medium containing 2% SBL. In addition, when the strains were grown under the same conditions, L4 had a higher growth rate and produced more PUFAs than L75.