Seong Myeong Yoon

Vibrio vulnificus secretes a broad-specificity metalloprotease capable of interfering with blood homeostasis through prothrombin activation and fibrinolysis

Vibrio vulnificus is a causative agent of serious food-borne diseases in humans related to the consumption of raw seafood. It secretes a metalloprotease that is associated with skin lesions and serious hemorrhagic complications. In this study, we purified and characterized an extracellular metalloprotease (designated as vEP) having prothrombin activation and fibrinolytic activities from V. vulnificus ATCC 29307. vEP could cleave various blood clotting-associated proteins such as prothrombin, plasminogen, fibrinogen, and factor Xa, and the cleavage could be stimulated by addition of 1 mM Mn2+ in the reaction. The cleavage of prothrombin produced active thrombin capable of converting fibrinogen to fibrin. The formation of active thrombin appeared to be transient, with further cleavage resulting in a loss of activity. The cleavage of plasminogen, however, did not produce an active plasmin. vEP could cleave all three major chains of fibrinogen without forming a clot. It could cleave fibrin polymer formed by thrombin as well as the cross-linked fibrin formed by factor XIIIa. In addition, vEP could also cleave plasma proteins such as bovine serum albumin and gamma globulin, and its broad specificity is reflected in the cleavage sites, which include Asp207-Phe208 and Thr272-Ala273 bonds in prothrombin and a Tyr80-Leu81 bond in plasminogen. Taken together, the data suggest that vEP is a broad-specificity protease that could function as a prothrombin activator and a fibrinolytic enzyme to interfere with blood homeostasis as part of the mechanism associated with the pathogenicity of V. vulnificus in humans and thereby facilitate the development of systemic infection.

First Record of the Genus Paragrandidierella (Crustacea: Amphipoda: Aoridae) from Korea

A newly recorded aorid species, Paragrandidierella minima Ariyama, 2002, from Korean waters is reported with a description and illustrations, and its generic features are considered. This species is characterized by the carpochelate gnathopod 1 in matured male, the posterodistal protrusion on peduncle 5 of antenna 2, the absence of the apical spine on inner plate of maxilliped, the minute apical projection on inner lobe of lower lip, the acute posteroproximal extension on the basis of each pereopod 5 and 6, the shape of uropods and telson, and the large inter-ramal process of uropod 1. This is the first report of the genus Paragrandidierella from Korea.

Purification and characterization of two forms of methanol dehydrogenases from a marine methylotroph.

Two methanol dehydrogenases (MDHs), MDH1 and MDH2, were purified from a marine methylotroph, Methylophaga sp. strain 1. Both enzymes had very similar properties, including the same native molecular weight, sizes of subunits and substrate specificity. The N‐terminal amino acid sequence of the α‐subunit of MDH2 differed from that of MDH1 by having a histidine residue at a highly conserved glutamate position, but both sequences showed approximately 50% homology to the α‐subunits of other MDHs. MDH1 had higher specific activity than MDH2 with respect to methanol and ethanol as a substrate. The two enzymes did not appear to be isoforms but that either MDH1 or MDH2 could be a mutant arising from spontaneous mutation.

Purification and characterization of a novel alkaline serine protease secreted by Vibrio metschnikovii

A novel extracellular alkaline serine protease secreted by Vibrio metschnikovii (V. metschnikovii) ATCC700040 cells was purified by three chromatographic steps and characterized in terms of enzymatic kinetics and substrate specificity. The purified enzyme (named AKP-Vm) was composed of a single polypeptide with an apparent molecular weight of 50 kDa on 12% SDS-polyacrylamide gel in the presence of CuCl₂. The optimal temperature and the pH for the enzyme were found to be 37˚C and 9.5, respectively. However, the enzyme activity was inhibited by inhibitors such as PMSF and aprotinin. AKP-Vm could hydrolyze a peptide bond at the carboxyl side of the arginine residue, as revealed by its amidolytic activity toward a chromogenic substrate, Boc-Val-Pro-Arg-pNA. The kinetic parameters of the enzyme were as follows: KM=0.91 mM, kcat=0.8 sec⁻¹ and kcat/KM=0.88 mM⁻¹sec⁻¹. AKP-Vm protease could cleave various blood coagulation-associated proteins, including fibrinogen, prothrombin and thrombin. In particular, the enzyme showed powerful fibrinogenolytic and fibrinolytic activities, as it could cleave all major chains of fibrinogen and also digest cross-linked fibrin. The results obtained suggest that AKP-Vm is a novel alkaline serine protease that can actively cleave fibrinogen and cross-linked fibrin.

Korea Barcode of Life Database System (KBOL)

A major concern regarding the collection and storage of biodiversity information is the inefficiency of conventional taxonomic approaches in dealing with a large number of species. This inefficiency has increased the demand for automated, rapid, and reliable molecular identification systems and large-scale biological databases. DNA-based taxonomic approaches are now arguably a necessity in biodiversity studies. In particular, DNA barcoding using short DNA sequences provides an effective molecular tool for species identification. We constructed a large-scale database system that holds a collection of 5531 barcode sequences from 2429 Korean species. The Korea Barcode of Life database (KBOL, http://koreabarcode.org) is a web-based database system that is used for compiling a high volume of DNA barcode data and identifying unknown biological specimens. With the KBOL system, users can not only link DNA barcodes and biological information but can also undertake conservation activities, including environmental management, monitoring, and detecting significant organisms.

Effects of Food Quality and Temperature on life History Traits of Moina macrocopa Reared in Laboratory

Life table experiments were performed in order to examine the effects of food quality on Moina macrocopa fed with four kinds of algal foods, Botryococcus sp., Scenedesmus subspicatus, Selenastrum capricornutum, and Chlorella sp., at 20°C. The temperature effects on M macrocopa were also assessed, feeding Chlorella at 17°C, 20°C, 25°C, and a combination of 28°C (light) and 25°C (dark). The cartilaginous Botryococcus cells were inappropriate food for Moina. Among the foods tested, Chlorella was the food of the best quality in all accounts of life history traits. Moina grown on Chlorella showed higher net reproductive rate (R0), longer mean and maximum longevities, earlier mean age at maturity, longer mean carapace length at maturity, larger mean clutch size, and shorter mean time interval between clutch productions than those grown on Selenastrum and Scenedesmus. An optimal temperature for Moina was 20°C. When Moina were grown on Chlorella at 20°C, they showed the highest r, the highest Ro, the shortest T, the longest mean longevity, the earliest mean age at maturity, the longest mean carapace length at maturity, and the largest mean clutch size. The results of life table experiments showed that the individual and population growth patterns were much more affected by low temperature (17°C) than by high temperature (≥25°C). In the optimal condition, the rvalue was very high, 5.1 in d‐1. In conclusion, the food quality and the temperature are the most important factors to govern the size and continuity of Moina population, by which the individual growth rates and reproductivity of members in the population can be controlled to survive in their environment such as small and temporary water bodies in nature.

Aroui minusetosus, a new species of Scopelocheiridae from Korea (Crustacea, Amphipoda, Lysianassoidea)

Abstract A new species, Aroui minusetosus sp. n., is recorded from Korean waters with detailed description and illustrations. A new key to all known Aroui is provided. The Korean material of this scopelocheirid is readily assigned to the genus Aroui by the presence of long and distally barbed setae on the outer plate of maxilla 2. This new species is distinguished from congeners by ventrally smooth coxae 1-3 and a setose posteroventral margin of coxa 4, the subchelate gnathopod 2 having a row of four robust setae on its posterior margin (including an elongate single locking seta), and the setation of all appendages which is less dense than in other species. This is the first record of scopelocheirid amphipods from Korean waters.

Two new lysianassoid amphipods of the genus Orchomenella (Amphipoda, Lysianassoidea, Lysianassidae, Tryphosinae) from South Korea

Two new species of the genus Orchomenella G. O. Sars, 1890 from South Korea are described here in detail. Orchomenella paucisetigera sp. nov. is characterized by an irregular and serrated palmar margin of gnathopod 1, non-serrated posterior margins of pleonal epimera 2-3, a more produced posteroventral corner of pleonal epimeron 3, and scarcely setose uropods 1-2. Orchomenella rugosa sp. nov. is easily discriminated from other congeners by its proximally slender basis and irregular palmar margin of gnathopod 1, marginal wrinkles ventrally of coxa 4, and the serrations and shapes of pleonal epimera and urosomite 1.

New records of Nuuanuidae (Crustacea: Amphipoda: Senticaudata) from Korean waters, with descriptions of one new genus and two new species

ABSTRACT The family Nuuanuidae Lowry and Myers, 2013 is first reported from Korean waters by the discovery of Nuuanu paracyclodactyla sp. nov. and Parvipalpus gen. nov., erected with the description of Parvipalpus holocaudatus sp. nov., along with their detailed descriptions and illustrations. The monotypic genus, Parvipalpus gen. nov., is characterized by the bi-articulate mandibular palp, the uni-articulate outer ramus of uropod 3, and no cleft telson. The new species, Nuuanu paracyclodactyla sp. nov., is very similar to Gammarella cyclodactyla (Hirayama, 1978) in the peculiar shape of propodus and dactylus on gnathopod 2 in mature males, but the former is distinguished readily by the absence of dorsal keels on the pleons and urosomite 1. New keys to genera of this family and to species of the genus Nuuanu are provided.

A new species of the genus Polycheria (Peracarida, Amphipoda, Dexaminidae) from South Korea

Polycheria acercauda sp. nov., an amphipod symbiotic with sponges and ascidians in Korean waters, is established herein as a new species, along with a detailed description and illustrations. This new species is closely related to the following three known species of the genus from the Far East: Polycheria amakusaensis Hirayama, 1984, P. japonica Bulycheva, 1952, and P. orientalis Hirayama, 1984. However, Polycheria acercauda sp. nov. can be distinguished from the other congeners by the following combination of characteristics: (1) on antenna 2, the anterior margin of peduncular article 4 is pubescent; (2) on gnathopod 2, the palm is clearly distinct; (3) on uropod 3, the inner ramus is lined with plumose setae; and (4) on the telson, the apices are acute. This is the first report of the genus Polycheria Haswell, 1879 belonging to the family Dexaminidae Leach, 1814 from Korean waters.