ABSTRACT
Changes in water temperature and salinity are responsible for a variety of physiological stress responses in aquatic organisms. Stress induced by these factors was recently associated with enhanced reactive oxygen species (ROS) generation, which caused oxidative damage. In the present study, we investigated the time-related effects of changes in water temperature and salinity on mRNA expression and the activities of antioxidant enzymes (SOD and CAT) and lipid peroxidation (LPO) in the gills and digestive glands of the ark shell, Scapharca broughtonii. To investigate physiological responses, hydrogen peroxide (H(2)O(2)), lysozyme activity, aspartate aminotransferase (AspAT), and alanine aminotransferase (AlaAT) were measured in the hemolymph. Water temperature and salinity changes significantly increased antioxidant enzyme mRNA expression and activity in the digestive glands and gills in a time-dependent manner. H(2)O(2) concentrations increased significantly in the high-temperature and hyposalinity treatments. LPO, AspAT and AlaAT levels also increased significantly in a time-dependent manner, while lysozyme activity decreased. These results suggest that antioxidant enzymes play important roles in reducing oxidative stress in ark shells exposed to changes in water temperature and salinity.
Subject(s)
Catalase/metabolism , Scapharca/enzymology , Stress, Physiological , Superoxide Dismutase/metabolism , Alanine Transaminase/metabolism , Animals , Aspartate Aminotransferases/metabolism , Catalase/genetics , Cloning, Molecular , DNA, Complementary/chemistry , DNA, Complementary/genetics , Digestive System/embryology , Digestive System/enzymology , Gene Expression Profiling , Gene Expression Regulation, Enzymologic , Gills/enzymology , Gills/metabolism , Hemolymph/enzymology , Hemolymph/metabolism , Hydrogen Peroxide/metabolism , Lipid Peroxidation , Molecular Sequence Data , Muramidase/metabolism , Osmolar Concentration , Reverse Transcriptase Polymerase Chain Reaction , Scapharca/genetics , Scapharca/metabolism , Sequence Analysis, DNA , Superoxide Dismutase/genetics , TemperatureABSTRACT
We cloned the thyroid hormone receptor alpha (TRalpha) and beta (TRbeta) cDNAs from the ovaries of the protandrous black porgy and compared the expression levels of TRalpha and TRbeta mRNA during the sex change in black porgy. We observed that the TRalpha mRNA by quantitative real-time PCR and protein levels by Western blot were highest in the mature ovaries. Additionally, TRbeta mRNA levels were only expressed highly in the mature ovaries when compared to any other gonadal stages. Then, we injected gonadotropin-releasing hormone analogue (GnRHa) to know the effects on TRs mRNA in immature black porgy. Injection with GnRHa resulted in a significant increase in TRalpha level while significantly reducing TRbeta level after 12h. We concluded that TRalpha was related in testicular development as well as ovarian development and TRbeta was only affect to ovarian development in black porgy. These results will provide a framework for better understanding of the role of TRs during sex change processes in this fish.
Subject(s)
Fish Proteins/metabolism , Perciformes/metabolism , Thyroid Hormone Receptors alpha/physiology , Thyroid Hormone Receptors beta/metabolism , Animals , Blotting, Western , Female , Fish Proteins/genetics , Gene Expression Regulation, Developmental/drug effects , Gene Expression Regulation, Developmental/genetics , Gonadotropin-Releasing Hormone/analogs & derivatives , Gonadotropin-Releasing Hormone/pharmacology , Male , Ovary/drug effects , Ovary/metabolism , Perciformes/genetics , Polymerase Chain Reaction , Sexual Maturation/drug effects , Sexual Maturation/genetics , Thyroid Hormone Receptors alpha/genetics , Thyroid Hormone Receptors alpha/metabolism , Thyroid Hormone Receptors beta/geneticsABSTRACT
Glutathione peroxidase (GPX) and glutathione S-transferase (GST) are key enzymes of cellular detoxification systems that defend cells against reactive oxygen species (ROS). In this study, we isolated the GPX and GST full-length cDNA and investigated the expression of these mRNAs from livers of olive flounder during salinity changes (35, 17.5, 8.75, 4 and 0 psu) by quantitative PCR (QPCR). GPX cDNA consists of 429 base pairs (bp) and encodes a protein of 142 amino acids. GST cDNA consists of 663 bp and encodes a protein of 220 amino acids. Both of GPX and GST mRNA expressions were the highest in 4 psu and then decreased in 0 psu. Also, the levels of Na(+) and Cl(-) decreased, and aspartate aminotransferase (AST) and alanine aminotransferase (ALT) increased during the experimental period. These findings provide molecular characterization of GPX and GST in olive flounder and suggest that GPX and GST play important roles in detoxification of ROS, thereby these maybe indicators of oxidative stress responses by salinity changes in olive flounder.
