Regulation of proteins related to melanogenesis by heartwood extract of<Emphasis Type="Italic">Morus bombycis</Emphasis> using proteome analysis

The ability of heartwood extract ofMorus bombycis in controlling the melanogenesis in B16 melanoma was investigated. An inhibitory effect was observed when the dose concentration was less than 10 mg/L. When the dose was 10 mg/L, the extracellular melanin accumulated was only 5% of the control. Proteome analysis with 2-D PAGE and MALDI-TOF showed that there were various proteins involved in inhibitory melanogenesis. It seems that down-regulation of TRP2, vacuolar protontranslocating ATPase 100 kDa subunit isoform a1-I and V-ATPase E2 subunit were involved in melanosome development and regulation that could reduce melanin synthesis.     

Elicitation kinetics of taxane production in suspension cultures of Taxus baccata Pendula

Methyl jasmonate increased taxane production in suspension cultures of Taxus baccata Pendula. Time course changes of taxane production after methyl jasmonate addition were different from normal kinetics without elicitation. Baccatin III and 10-deacetyl baccatin III were detected first and paclitaxel, 10-deacetyl taxol and cephalomanine followed each other in sequence. Paclitaxel was not a dead-end metabolite.     

The leader sequence of streptokinase is responsible for its post-translational carboxyl-terminal cleavage

When the expression of streptokinase from two tac promoter-controlled expression vectors, one of these deleted a putative leader sequence of streptokinase and the other not, was compared, both normal and degraded streptokinase were detected in proteins expressed from the leader-contained vector, but only normal streptokinase was detected from the leader-deleted vector. These findings indicate that the characteristic carboxyl-terminal cleavage of streptokinase is correlated with its leader sequence and occurs during the defective secretion. The homogeneous preparation of streptokinase was facilitated by expressing from this leader-deleted vector.     

Purification and characterization of angiotensin I converting enzyme (ACE) inhibitory peptides from Alaska pollack (Theragra chalcogramma) skin

Proteolytic digestion of gelatin extracts from Alaska Pollack (Theragra chalcogramma) skin brings about a high angiotensin I converting enzyme (ACE) inhibitory activity. Gelatin extracts were hydrolyzed by serial protease-treatments in the order of Alcalase, pronase E, and collagenase using a three-step recycling membrane reactor. Fragments arising from the third step were composed of peptides ranging from 0.9 to 1.9 kDa and responsible for ACE inhibitory activity. Catalytically active two peptides were separated by the consecutive chromatographic methods including gel filtration, ion-exchange chromatography, and reverse-phase high performance liquid chromatography. The isolated peptides were composed of Gly-Pro-Leu and Gly-Pro-Met and showed IC₅₀ values of 2.6 and 17.13 μM, respectively. These results suggested that Gly-Pro-Leu would be useful as a new antihypertensive agent.     

<Emphasis Type="Italic">In Planta</Emphasis> Measurements of Na<Superscript>+</Superscript> Using Fluorescent Dye CoroNa Green

Fluorescent indicators of Na⁺ are valuable tools for nondestructive monitoring of its spatial and temporal distribution in plants. We tested whether CoroNa Green fluorescent dye, a newly developed sodium indicator, is suitable for measuring relative concentrations in planta. To determine the ideal conditions for its use, we incubated NaCl-pretreated Arabidopsis thaliana seedlings with different concentrations of CoroNa Green and visualized fluorescence in each organ with a fluorescein isothiocyanate filter. When 50 μM of dye was applied, fluorescence was distributed more uniformly and intensely in the root tips than in other tissues. Under those conditions, fluorescence gradually increased in the root tips when Na⁺ was bound to CoroNa Green for concentrations up to 100 mM NaCl. Confocal fluorescence microscopy revealed that when Arabidopsis seedlings were incubated with the same concentration of NaCl, the sos1 mutant had much stronger fluorescence than the wild type. This report is the first to describe the properties of CoroNa Green for measuring Na⁺ content in intact plants and demonstrates the usefulness of this technique for investigating the mechanism of Na⁺ homeostasis.     

Baseline frequency of sister-chromatid exchanges in 142 persons of the general Korean population.

Baseline frequencies of sister-chromatid exchange (SCE) were measured in lymphocytes of 142 healthy Koreans ranging in age from newborn infants to the fifties. The overall mean frequency of SCE was 8.78 +/- 0.24/cell. However, highly significant differences were found between individuals. The mean SCE values of the newborn babies and small children less than 10 years old were significantly lower than those of other age groups. No age effect was, however, observed in adolescent and adult subjects. Females had statistically higher SCE levels than males. The mean SCE frequencies of smokers, measured in male subjects more than 10 years old, were slightly, but statistically significantly, higher than those of non-smokers.     

Full-length enriched cDNA library construction from tissues related to energy metabolism in pigs

Genome sequencing of the pig is being accelerated because of its importance as an evolutionary and biomedical model animal as well as a major livestock animal. However, information on expressed porcine genes is insufficient to allow annotation and use of the genomic information. A series of expressed sequence tags of 5′ ends of five full-length enriched cDNA libraries (SUSFLECKs) were functionally characterized. SUSFLECKs were constructed from porcine abdominal fat, induced fat cells, loin muscle, liver, and pituitary gland, and were composed of non-normalized and normalized libraries. A total of 55,658 ESTs that were sequenced once from the 5′ ends of clones were produced and assembled into 17,684 unique sequences with 7,736 contigs and 9,948 singletons. In Gene Ontology analysis, two significant biological process leaf nodes were found: gluconeogenesis and translation elongation. In functional domain analysis based on the Pfam database, the beta transducin repeat domain of WD40 protein was the most frequently occurring domain. Twelve genes, including SLC25A6, EEF1G, EEF1A1, COX1, ACTA1, SLA, and ANXA2, were significantly more abundant in fat tissues than in loin muscle, liver, and pituitary gland in the SUSFLECKs. These characteristics of SUSFLECKs determined by EST analysis can provide important insight to discover the functional pathways in gene networks and to expand our understanding of energy metabolism in the pig.     

Gangliosides are involved in neural differentiation of human dental pulp-derived stem cells

Human dental pulp-derived stem cells (hDPSCs) have been considered alternative sources of adult stem cells because of their potential to differentiate into multiple cell lineages. This study investigated the possible role of gangliosides in the neural differentiation of hDPSCs. When hDPSCs were cultured under neural differentiation conditions, expression of neural cell marker genes such as Nestin, MAP-2, and NeuN was detected. Immunostaining and high-performance thin-layer chromatography analysis showed that an increase in ganglioside biosynthesis was associated with neural differentiation of hDPSCs. Specifically, a significant increase in GD3 and GD1a expression was observed during neural differentiation. To confirm the role of gangliosides in neural differentiation, ganglioside biosynthesis was inhibited in hDPSCs by knockdown of UDP-glucose ceramide glucosyltransferase (Ugcg), which prevented differentiation into neural cells. These results suggest that gangliosides may play a role in the neural differentiation process of hDPSCs.     

Lipase-catalyzed hydrolysis of fish oil in an optimum emulsion system

In this study, fish oil was hydrolyzed by lipase in a fish oil-in-water emulsion system in an effort to improve the functional properties of fish oil. Lipase activity was found to depend on the quality of the water/fish oil interface area. We selected several suitable emulsifiers, and their emulsifying activities were evaluated under a variety of conditions, including concentration, water-oil ratios, pH values, and temperature. Among the selected emulsifiers, the emulsifying activity of gelatin was higher than those of carboxymethyl chitin (CM-chitin), bovine serum albumin, and Tween-20, all of which are commercial emulsificers Moreover, the emulsifying activity of the gelatin solution was the highest at 0.5%, and was reduced with increasing concentrations of above 1%. The optimal water-oil ratio, pH, and temperature conditions were 40% (w/v), pH 8.0 and 40°C, respectively. Under these conditions, the emulsifying activity of gelatin solution was 86%. The emulsion structure of the gelatin solution was characterized by high density and small particle size. The degree of sardine oil hydrolysis in the emulsion system was 50% higher than that of the non-emulsion system. The lipid species of the lipase-prepared sardine oil hydrolysates were identified as triacylglycerol, 1,3- and 1,2-diacylglycerol, monoacylglycerol, and fatty acid.