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241.
Identification and Characterization of Megalocytivirus Type 3 Infection with Low Mortality in Starry Flounder,Platichthys stellatus,in Korea 下载免费PDF全文
Ji Woong Jin Yi Kyung Kim Suhee Hong Young Chul Kim Woo Ju Kwon Hyun Do Jeong 《Journal of the World Aquaculture Society》2018,49(1):229-239
MVSF‐12 belonging to megalocytivirus type 3 was isolated from cultured starry flounder; Platichthys stellatus, at the moribund or subclinical stage with low mortalities in Korea. Of 20 apparently healthy fish in the farms, 17 were also confirmed in nested polymerase chain reaction to be infected by megalocytivirus. When starry flounder; rock bream, Oplegnathus fasciatus; and olive flounder, Paralichthys olivaceus, were artificially infected by MVSF‐12 or iridovirus sachun‐1 (IVS‐1, megalocytivirus type 1), starry flounder and olive flounder showed no mortality until Day 24, without any clinical signs including enlarged spleen, while rock bream showed 100% mortality by IVS‐1 infection within 11 d but no mortality by MVSF‐12. Although it was not pathogenic, MVSF‐12 in infected fish at Day 24 was viable when successfully cultured in vitro using primary rock bream embryo cells and produced a cytopathic effect (CPE) with the viral copy numbers between 1.76 × 107 and 5.23 × 107/mL of culture supernatant. In conclusion, this study demonstrates the low pathogenicity of MVSF‐12 and low susceptibility of starry flounder and olive flounder to both MVSF‐12 and IVS‐1. Indeed, MVSF‐12 at the subclinical stage could be replicated with CPE in vitro, indicating a possibility to induce pathogenic effects and mortality under adverse environment or physiologic conditions. 相似文献
242.
Temporal expression analyses of pancreatic and gastric digestive enzymes during early development of the olive flounder (Paralichthys olivaceus) 下载免费PDF全文
Young Mee Lee Jeong‐Ho Lee Jae Koo Noh Hyun Chul Kim Choul‐Ji Park Jong‐Won Park Gyeong Eon Noh Kyung‐Kil Kim 《Aquaculture Research》2017,48(3):979-989
The olive flounder (Paralichthys olivaceus) is one of the most important aquaculture species in Korea. Previous studies focused on the morphological changes and only analysed digestive enzyme expression patterns of certain digestive systems. A comprehensive analysis of the pancreatic and gastric digestive enzymes of the olive flounder in its early developmental stages has not been performed. In this study, we determined the mRNA expression levels of pancreas and stomach digestive enzymes by extracting total RNA from the whole body of olive flounders from hatching to post‐metamorphosis and conducting real‐time PCR analysis with gene‐specific primers for each isoform. The pancreatic digestive enzymes were initially and strongly expressed from the first feeding period to pre‐metamorphosis. The expression of trypsinogen 3 was detected from the early stage of development to metamorphosis, whereas trypsinogen 2 was significantly increased only in the post‐metamorphosis period. The mRNA expression of pepsinogen was only detected at metamorphosis and corresponded to stomach differentiation. The lipid digestive‐related enzymes had already reached a certain level at the beginning of hatching, then increased during the early developmental stage and gradually decreased before metamorphosis. These results suggest that food ingestion is exclusively digested by pancreatic digestive enzymes and trypsinogen 3 during the early developmental stage until pre‐metamorphosis, and it then fully switches to digestion by pepsinogen and trypsinogen 2 in mid‐metamorphosis. In conclusion, understanding the expression profiles of digestive enzymes in the pancreas and stomach during the early developmental stages is an important consideration when developing formulated larval diets for aquacultured olive flounder. 相似文献
243.
Kyung Mi Lee Yoshiaki Yamada Akihiro Okamura Katsumi Tsukamoto Toyoji Kaneko 《Fisheries Science》2013,79(1):77-86
We explored osmoregulatory ability and mechanisms of ion and water regulation in Japanese eel leptocephali. Tissue osmolality of leptocephali ranged from 360 to 540 mOsm/kg·H2O. Immunocytochemical observations revealed that Na+/K+-ATPase-immunoreactive mitochondrion-rich (MR) cells were distributed over the entire body surface of leptocephali. Using a fluorescent sodium indicator and the chloride test, we localized Na+ and Cl? secreting sites at the apical region of cutaneous MR cells. To further examine drinking behavior and water absorption in the intestine, leptocephali were exposed to seawater containing dextran labeled with Alexa Fluor. To calculate relative water absorption, fluorescent intensity was measured along the digestive tract. Whereas water was hardly absorbed in the stomach and intestine, water absorption predominantly took place in the rectum. Our findings indicate that Japanese eel exert hyposmoregulatory ability as early as during leptocephalus stages, secreting Na+ and Cl? through cutaneous MR cells and primarily absorbing water from ingested seawater in the rectum. 相似文献
244.
Jin‐Hyoung Kim Hyoung‐Joo Jeon Jae‐Min Baek Kyung‐Nam Han Hans‐Uwe Dahms 《Aquaculture Research》2013,44(6):985-994
Endocrine disrupting chemicals (EDCs) are of substantial concern when contaminating waters. We studied gene expression of larvae from river pufferfish, Takifugu obscurus exposed to EDCs. We cloned the full‐ or partial‐length cDNA sequence of genes related to the cortisol pathway, such as the glucocorticoid receptor (GR), mineralocorticoid receptor (MR), heat shock protein (HSP) 70 and 90, phosphoenolpyruvate carboxykinase (PEPCK) and the FK506‐binding protein 4 (FKBP52). The tissue and time‐dependent expression of mRNA was studied by real‐time PCR in T. obscurus exposed to two representative EDCs (bisphenol‐A and 4‐tert‐octylphenol). HSP70, HSP90, MR and FKBP52 mRNA expression level was much higher than GR and PEPCK expression. GR mRNA expression level was significantly upregulated after 48 h in both EDC‐treated fish groups compared with the control. Both groups also showed down‐regulation patterns after 48 h. The initial expression of PEPCK in both groups was down‐regulated after 24 h. In the bisphenol‐A treated group, the expression of FKBP52 showed substantially high up‐regulation from 6 to 48 h after exposure, and then strikingly reduced its expression level at 72 h. Our results provide insights into the EDCs metabolizing system of T. obscurus and offers baseline information for further research related to the possible use as a bio‐indicator of this commercially important aquaculture fish species. 相似文献
245.
Jin Hoon Kim Jung Soo Kim Ji Hoon Jang Min Seong Kim Young-Wook Chang Dae Young Lim Dong Hyun Kim 《Fibers and Polymers》2016,17(5):671-677
We prepared long carbon fiber (LCF)-reinforced thermoplastic composites using a compatibilizer of itaconic acid grafted polypropylene (PP-g-IA). We confirmed the structure of PP-g-IA and investigated the compatibilizing effects of PPg- IA on LCF/polypropylene composites. The tensile strength, tensile moduli, flexural strength, and flexural moduli of the composites increased with increasing PP-g-IA content in the thermoplastic composites. Using single pull-out analyzing system, we found PP-g-IA improved interfacial strength between the carbon fiber and PP matrix. The thermal properties of the composites were measured by thermogravimetric analysis (TGA). We could observe that LCF enhanced the mechanical properties and thermal decomposition temperature of the polypropylene (PP) composites, compared with neat PP. The fractured surfaces of PP/PP-g-IA/LCF composites showed that PP-g-IA was effective for improving the interfacial adhesion between LCF and PP matrix. 相似文献
246.
Hyun-Na Koo Soon-Gyu Lee Seung-Hwan Yun Hyun Kyung Kim Yong Soo Choi Gil-Hah Kim 《Journal of insect science (Online)》2016,16(1)
This study compared stress-induced expression of Cu-Zn superoxide dismutase (SOD1) and thioredoxin reductase (TrxR) genes in the European honeybee Apis mellifera L. and Asian honeybee Apis cerana F. Expression of both SOD1 and TrxR rapidly increased up to 5 h after exposure to cold (4°C) or heat (37°C) treatment and then gradually decreased, with a stronger effect induced by cold stress in A. mellifera compared with A. cerana. Injection of stress-inducing substances (methyl viologen, [MV] and H2O2) also increased SOD1 and TrxR expression in both A. mellifera and A. cerana, and this effect was more pronounced with MV than H2O2. Additionally, we heterologously expressed the A. mellifera and A. cerana SOD1 and TrxR proteins in an Escherichia coli expression system, and detection by SDS-PAGE, confirmed by Western blotting using anti-His tag antibodies, revealed bands at 16 and 60 kDa, respectively. Our results show that the expression patterns of SOD1 and TrxR differ between A. mellifera and A. cerana under conditions of low or high temperature as well as oxidative stress. 相似文献
247.
This study examined the thermal and mechanical properties of polypropylene filaments reinforced with multi-walled carbon nanotubes (MWNTs). The MWNTs were functionalized with maleic anhydride polypropylene to increase the interfacial interactions between the CNTs and polypropylene. PP/MWNT composites with different concentrations of MWNTs were prepared by melt compounding using a twin screw extruder. The composites of the filament were then post drawn and heat treated. Tensile tests showed increased strength with the addition of only 0.1 wt% while there were only slight changes in elongation. The thermal properties were also slightly enhanced by the MWNTs. 相似文献
248.
Four new streptoglycerides E–H (1–4), with a rare 6/5/5/-membered ring system, were isolated from a marine-derived actinomycete Streptomyces specialis. The structures of 1–4 were elucidated by detailed analysis of HRESIMS, 1D and 2D NMR data and ECD spectra as well as comparison of their spectroscopic data with those reported in literature. Compounds 1–4 showed significant anti-inflammatory activity by inhibiting lipopolysaccharide (LPS)-induced nitric oxide (NO) production in Raw 264.7 cells with IC50 values ranging from 3.5 to 10.9 µM. Especially, 2 suppressed mRNA expression levels of iNOS and IL-6 without cytotoxicity. 相似文献
249.
The objective of this study is to develop an advanced stab proof material composed of shear thickening fluid (STF) and Kevlar
fabric. In this study, silica/ethylene glycol suspension was prepared for the use as the STF, and it was analyzed by a rheometer,
TEM and dynamic light scattering spectrophotometer. From the results, it was observed that the STF significantly showed the
reversible liquid-solid transition at a certain shear rate. Also, we treated Kevlar plain fabric with the STF by 1 dip-1nip
finishing method and investigated the mechanical and stab resistant properties. Through the investigation of the fumed silica/Kevlar
composite fabric, we found that the STF impregnation significantly improved the stab resistance of Kevlar fabric against spike
threats and so enhance the protection performance of Kevlar fabric as a stab proof material. 相似文献
250.
Polyurethane (PU) layer and copolymer consisted of the different molecular weights (1000 and 2000 g/mol) of poly(propylene
glycol) (PPG) were prepared. The damping and mechanical properties of these materials were compared with PU1000 made by PPG
having the molecular weight of 1000 g/mol. The optimum composition of PU2000 used for PU layer and copolymer was diphenylmethane
diioscynate (MDI)/propylene glycol (PPG)/butanediol (BD) (1/0.3/0.7) based on the damping and mechanical properties. The damping
peak of PU copolymer was higher than those of PU layer and PU1000 in low temperature range (−30–10 °C). For application in
noise reduction, the transmission loss of the mechanical vibration through solid structure was measured. PU layer and copolymer
were used as a damping layer. The transmission loss of PU copolymer was more effective than those of PU layer and PU1000 in
the experimental frequency range. 相似文献