Transient expression of phospholipase D1 during heart development in rats

The expression of phospholipase D (PLD) isozymes was examined in the hearts of rats at different stages of development. Immunoprecipitation and Western blot analysis revealed weak PLD1 expression in the hearts of day 17 embryos. The level of PLD1 protein increased transiently 0 and 3 days postpartum, and declined gradually beginning 7 days after birth. Immunohistochemistry revealed weak PLD1 immunostaining in some cells at embryonic day 17. In contrast, some vascular endothelial cells and cardiomyocytes were immunostained typically at days 0, 3, and 7 after birth. After postnatal day 21, weak PLD1 expression was immunodetected in some vascular endothelial cells and cardiomyocytes. This suggests that the PLD1 protein in the heart is strongly associated with the early postnatal development of the heart in rats.     

Seroprevalence of leptospirosis in Korean municipal zoo animals

From 2002 to 2005, we collected 118 serum samples from 34 species belonging to 13 families of zoo animals in Korea and determined the prevalence of antibodies for 18 serovars of Leptospira spp. using the microscopic agglutination test (MAT). Twenty-nine (25%) of the serum samples tested were positive for one or more of the serovars. There were no significant differences in relation to genders: 23% and 26% of positives occurring in male and female animals, respectively (P>0.05). However, the seroprevalence for the Leptospira spp. was significantly higher (P<0.05) in herbivores (45%) than in either carnivores (17%) or omnivores (17%). Among the 5 serovars detected in this study, the most common was sejroe (n=27; 87% of all positive reactions). All positive reactions showed low titers (< or = 1:200) and the positives were most frequently detected in 1:25 (58%) and 1:50 (23%) serum dilutions. The highest antibody titer (1:200) was observed for the serovars sejroe (n=1) and bratislava (n=1). We conclude that the exposure of zoo animals to Leptospira spp. is relatively common in Korea and produces low MAT titers, with sejroe being the most commonly encountered serovar.     

Marine Peptides and Their Anti-Infective Activities

Marine bioresources are a valuable source of bioactive compounds with industrial and nutraceutical potential. Numerous clinical trials evaluating novel chemotherapeutic agents derived from marine sources have revealed novel mechanisms of action. Recently, marine-derived bioactive peptides have attracted attention owing to their numerous beneficial effects. Moreover, several studies have reported that marine peptides exhibit various anti-infective activities, such as antimicrobial, antifungal, antimalarial, antiprotozoal, anti-tuberculosis, and antiviral activities. In the last several decades, studies of marine plants, animals, and microbes have revealed tremendous number of structurally diverse and bioactive secondary metabolites. However, the treatments available for many infectious diseases caused by bacteria, fungi, and viruses are limited. Thus, the identification of novel antimicrobial peptides should be continued, and all possible strategies should be explored. In this review, we will present the structures and anti-infective activity of peptides isolated from marine sources (sponges, algae, bacteria, fungi and fish) from 2006 to the present.     

Pathological characteristics of olive flounder <Emphasis Type="Italic">Paralichthys olivaceus</Emphasis> experimentally infected with <Emphasis Type="Italic">Streptococcus parauberis</Emphasis>

Pathological characteristics of olive flounder Paralichthys olivaceus experimentally infected with Streptococcus parauberis were studied. Various stressful conditions, aeration and netting stress in particular, led to induced mortality by S. parauberis. Netting stress-induced mortality was positively correlated to bacterial dose and stressful conditions. Inflammation of the heart and pericarditis was the major pathological change observed in olive flounder experimentally infected with S. parauberis. During the infected period, the number of bacteria in the infected olive flounder was recorded over time. S. parauberis remained in all fish organs tested, especially in the heart and brain.     

Effect of the residuum extract of Siberian ginseng Eleutherococcus senticosus on non-specific immunity in olive flounder Paralichthys olivaceus

ABSTRACT:   To determine the effects of Siberian ginseng residuum extract (SG-RE) Eleutherococcus senticosus on non-specific immunity in olive flounder Paralichthys olivaceus , the fish were provided either a commercial diet or a diet supplemented with Siberian ginseng (3 and 7%) for 8 weeks. The fish that were fed a diet supplemented with 3% SG-RE exhibited improved non-specific immunity, not only cellular responses such as phagocytic activity and nitroblue tetrazolium reduction by anterior-kidney leukocytes, but also humoral response such as lysozyme activity in the serum and skin mucus. Moreover, the fish that were provided SG-RE developed resistance to Edwardsiella tarda and Vibrio anguillarum infection.     

Pathogenicity comparison of high- and low-virulence strains of Vibrio scophthalmi in olive flounder Paralichthys olivaceus

Vibrio scophthalmi, a bacterial pathogen of olive flounder Paralichthys olivaceus, exhibits strain-dependent virulence. No information is available on the comparative pathogenicity of different strains of V. scophthalmi toward olive flounder. In this study, high- and low-virulence strains (HVS and LVS, respectively) were compared in terms of their pathogenic characteristics, including adhesion and survival, superoxide dismutase (SOD) activity, and extracellular products (ECP) of bacterial cells. The cell-mediated defense of macrophages from olive flounder against V. scophthalmi infection in vitro was also investigated. The results demonstrated that the SOD activity of the HVS was higher than that of the LVS. The number of viable cells of the HVS in serum increased by two log units after 18 h, whereas that of the LVS decreased. The number of cells of the HVS in skin mucus increased significantly while that of the LVS remained constant. The LD₅₀ values of the HVS and LVS ECP toward olive flounder were 10.14 and 15.99 μg protein/g fish, respectively. The ECP were positive for naphthol-AS-BI-phosphohydrolase, lipase, gelatinase, and leucine arylamidase. The extracellular O₂ ^? overflow and intracellular O₂ ^? concentration of macrophages induced by the HVS were lower than those induced by the LVS. Significantly more nitric oxide was produced by the HVS than by the LVS.     

Effect of dietary taurine levels on the conjugated bile acid composition and growth of juvenile Korean rockfish Sebastes schlegeli (Hilgendorf)

This study was conducted to investigate the effects of different taurine levels on the conjugated bile acid composition and growth of juvenile rockfish. Five taurine level diets were made by the supplementation of taurine (0%, 0.5%, 1.0%, 1.5% and 2.0%) to a basal diet. Fish meal washed with 70% ethanol to exclude taurine was used for the sole protein source. Feeding experiments were accomplished at 15°C using juvenile fish (initial BW: 13.5 g). Fish were fed the experimental diets for 4 months. At the end of experiments, fish were weighed and stored at ?80°C for analysis of free amino acids and conjugated bile acids contents. The growth performance and feed efficiency of Korean rockfish were improved by taurine supplementation in the experimental diets. The taurine contents of the whole body increased with the increase in the taurine supplementation. The primary conjugated bile acids in gall bladder were taurocholic acid (83.5–165.6 mg mL^?1) and taurochenodeoxycholic acid (6.3–20.0 mg mL^?1). Total bile acids increased with increases in dietary taurine. Taurocholic acid content was more than 95% of the total conjugated bile acids. This indicates that taurine is the sole amino acid to make conjugated bile acid in Korean rockfish. Dietary taurine levels improved the conjugated bile acid composition in juvenile Korean rockfish.     

Influence of water temperature on spawning induction and larval development of the sea squirt Halocynthia ritteri (Oka, 1906)

In order to establish a large-scale hatchery technique for the sea squirt Halocynthia ritteri , the influences of water temperature on spawning induction, larval development and survival of H. ritteri were studied under laboratory conditions. The larvae of H. ritteri exhibited high sensitivity to changes in temperature. As temperature increased from 10 to 21 °C, the duration of larval stage was inversely related to temperature and the time to reach attached larvae stage decreased from 42.0 to 59.4 h. The biological minimum temperature for the early development of H. ritteri was estimated to be 0.22 °C. In relation to temperature, quadratic equations showed significant fits to the data of spawning rate, fecundity, fertilization, larval survival and attachment. Optimal temperatures for spawning rate, fecundity, fertilization rate, larval survival rate and attachment rate were estimated to be 14.9, 14.7, 13.2, 14.1 and 14.7 °C respectively. It is concluded that the range of 13–15 °C is optimal for spawning and larval rearing of sea squirts.     

Molecular characterization of myostatin‐like genes expressed highly in the muscle tissue from Morotoge shrimp,Pandalopsis japonica

Myostatin is one of the transforming growth factor (TGF)‐β family members and plays inhibitory roles in the development and growth of muscle in mammals. Mammalian myostatins have been studied intensively, considering its medical and industrial potential use. Still, limited information is available about myostatin homologues in crustaceans. In the present study, we isolated for the first time cDNA that encodes for myostatin‐like protein (Pj‐MSTN) from Morotoge shrimp, Pandalopsis japonica. The putative mature peptide of Pj‐MSTN was composed of 109 amino acids, which contains an additional amino acid residue compared with mammalian myostatins. Pj‐MSTN exhibited 32% amino acid sequence identity and 52% similarity to human myostatin. Multiple sequence alignment analysis indicated that Pj‐MSTN shared the conserved proteolytic cleavage site (RXXR) for its maturation and nine cysteine residues for disulphide bridges. These results suggest that Pj‐MSTN has conserved the three‐dimensional structure of TGF‐β family members in vertebrates. Phylogenetic analysis suggests that Pj‐MSTN is a primitive form of vertebrate myostatin and GDF11. The expression of Pj‐MSTN was not just identified in muscular tissues, suggesting that Pj‐MSTN functions differently from mammalian myostatin. Ablation of the X‐organ/sinus gland complex significantly reduced the expression of Pj‐MSTN in most tissues, suggesting its potential association with moulting.