Heat shock protein 70 gene expression and stress response of red-spotted (Epinephelus akaara) and hybrid (E. akaara female × E. lanceolatus male) groupers to heat and cold shock exposure.

The importance of the temperature tolerance of fish is increasing due to climate change caused by global warming. This study examined the expression of the heat shock protein 70 (HSP70) gene, and plasma cortisol and glucose levels, as a stress response in red-spotted and hybrid groupers during exposure to heat and cold shock. Temperature in the tank where fishes acclimated at 20℃ was gradually increased or decreased, respectively, to examine the survival rate of fish. The result showed a higher survival rate of the hybrid than that of the red-spotted grouper upon exposure to a higher temperature. To further analyze the factors associated with temperature-associated stress, fishes were collected from different temperatures which changed from 20 to 30℃ or 10℃, respectively, and then back to 20℃. The expression levels of the gene encoding heat shock protein 70 (HSP70) were analyzed by qPCR using cDNA prepared from RNA extracted from the brain. A higher level of HSP70 transcript was detected in the hybrid during heat shock exposure. Analysis of cortisol and glucose from the blood of fish collected during the acclimation periods clearly indicated that the level of cortisol was increased upon temperature shift although a slight difference in the degrees of changes timing was slightly different between red-spotted grouper and hybrid. The results showed a correlation between the level of HSP70 and survival rate upon exposure to higher temperature shock. This study provides basic information regarding whether HSP70 expression increases the survival rate of fish subjected to rapid temperature changes.

Cryopreservation of Roughscale Sole (Clidoderma asperrimum) Sperm: Effects of Cryoprotectant, Diluent, Dilution Ratio, and Thawing Temperature.

The roughscale sole, Clidoderma asperrimum is categorized as an endangered species. Sperm freezing is essential for preserving gametes. This study examined the CPA concentration, diluent, dilution ratio, and thawing temperature to design a sperm cryopreservation protocol for roughscale sole. The variables examined included sperm motility and kinematics, cell survival, fertilization, and DNA fragmentation. Sperm motility parameters were assessed via computer-assisted sperm analysis using a CEROS II instrument. Cell survival rate and DNA damage were assessed using the Cell Counting Kit-8 and single-cell gel electrophoresis assay, respectively. Sperm preservation was tested using several CPAs, including ethylene glycol, dimethyl sulfoxide (DMSO), glycerol, propylene glycol, and methanol. The diluents tested were 300 mM sucrose, 300 mM glucose, Stein's solution, Ringer's solution, and Hank's solution. The optimal conditions for sperm cryopreservation were 10% DMSO + Stein's solution. After thawing, sperm motility was highest with a 1:1 dilution ratio (sperm to CPA + diluent), at 69.20 ± 0.32%; thawing at 10 °C was optimal for post-thaw motility (72.03 ± 0.95%). The highest fertilization rate (40.00 ± 1.22%) was obtained using DMSO. The fresh sperm had the lowest tail DNA, followed by 10% DMSO + Stein's solution. The developed cryopreservation methods can be used in roughscale sole hatcheries.

Dead-End (dnd) Gene Cloning and Gonad-Specific Expression Pattern in Starry Flounder (Platichthys stellatus).

dnd is a germline-specific maternal RNA expressed in various vertebrate classes, which encodes an RNA-binding protein that is essential for PGC migration. The purpose of this study is fundamental research about starry flounder dnd gene for germ cell marker development. In this study, we cloned and analyzed the expression levels of Platichthys stellatus dead end (psdnd) in various tissues and embryonic stages. The psdnd gene was isolated from starry flounder ovaries, cloned into a pGEM-t vector, and sequenced. Full-length of psdnd cDNA was 1495 bp long, encoding 395 amino acids. psdnd expression levels were investigated by real-time polymerase chain reaction (qRT-PCR) in various tissues and embryo developmental stages. psdnd transcripts were detected in the testes and ovaries, but not in somatic tissues. Embryonic psdnd expression levels were higher during early embryo development stages than during late embryogenesis; psdnd expression was highest at the 1 cell stage, then gradually decreased throughout the subsequent developmental stages. The spatial expression pattern was analyzed by whole-mount in situ hybridization (WISH). The psdnd transcripts migration pattern was similar with zebrafish (Danio rerio). Our results suggest that psdnd may function as a germ cell-specific marker.

Tyrosinase Inhibitory and Anti-oxidative Effects of Lactic Acid Bacteria Isolated from Dairy Cow Feces.

Overproduction and accumulation of melanin cause a number of skin diseases. The inhibitors of tyrosinase are important for the treatment of skin diseases associated with hyper-pigmentation after UV exposure and application in cosmetics for whitening and depigmentation. Reactive oxygen species (ROS) including hydrogen peroxide are generated by chemical substances and metabolic intermediates and cause various diseases including cancer and heart diseases. We have isolated four different lactic acid bacteria (LAB) strains from dairy cow feces and investigated the tyrosinase inhibition and anti-oxidative effects of culture filtrates prepared from the isolated bacteria, which are designated as EA3, EB2, PC2, and PD3. To investigate optimal culture conditions isolated LAB strains, the measurements of tyrosinase inhibitory and anti-oxidative activities were performed. The results of tyrosinase inhibitory activities revealed that Enterococcus sp. EA3 showed about 65% at culture conditions (14 h, 30 °C, pH 8, and 0% NaCl), Enterococcus sp. EB2 about 65% at culture conditions (12 h, 30 °C, pH 9, and 0% NaCl), Pediococcus sp. PC2 about 80% at culture conditions (20 h, 30 °C, pH 6, and 0% NaCl), and Pediococcus sp. PD3 about 80% at culture conditions (20 h, 30 °C, pH 8, and 0% NaCl), respectively. In addition, anti-oxidative activities against four different LAB strains showed approximately more than 30% at optimal conditions for the measurements of tyrosinase inhibitory activities. From the results, we have suggested that the isolated four LAB strains could be useful for a potential agent for developing anti-oxidants and tyrosinase inhibitors.