Thioredoxin (Trx) proteins are involved in many biological processes especially the regulation of cellular redox homeostasis. In this study, two Trx cDNAs were cloned from the mussel Mytilus galloprovincialis using ra...Thioredoxin (Trx) proteins are involved in many biological processes especially the regulation of cellular redox homeostasis. In this study, two Trx cDNAs were cloned from the mussel Mytilus galloprovincialis using rapid amplification of cDNA ends-polymerase chain reaction (RACE-PCR). The two cDNAs were named MgTrx1 and MgTrx2, respectively. The open reading frames of MgTrx1 and MgTrx2 were 318 and 507 base pairs (bp) and they encoded proteins of 105 and 168 amino acids with estimated molecular masses of 11.45 and 18.93 kDa, respectively. Sequence analysis revealed that both proteins possessed the conserved active site dithiol motif Cys-Gly-Pro-Cys. In addition, MgTrx2 also possessed a putative mitochondrial targeting signal suggesting that it is located in the mitochondria. Quantitative real-time polymerase chain reaction (qPCR) revealed that both MgTrx1 and MgTrx2 were constitutively expressed in all tissues examined. The MgTrx1 transcript was most abundant in hemocytes and gills, whereas the MgTrx2 transcript was most abundant in gonad, hepatopancreas, gill and hemocytes. Following Vibrio anguillarum challenge, the expression of MgTrx1 was up-regulated and reached its peak, at a value 10-fold the initial value, at 24 h. Subsequently, expression returned back to the original level. In contrast, the expression level of MgTrx2 was down-regulated following bacterial stimulation, with one fifth of the control level evident at 12 h post challenge. These results suggest that MgTrx1 and MgTrx2 may play important roles in the response of M. galloprovincialis to bacterial challenge.展开更多
A series of laboratory incubation experiments were conducted to examine the decomposition of algal organic matter in clay-enriched marine sediment under oxic and anoxic conditions.During the 245-day incubation period,...A series of laboratory incubation experiments were conducted to examine the decomposition of algal organic matter in clay-enriched marine sediment under oxic and anoxic conditions.During the 245-day incubation period,changes in the concentrations of TOC,major algal fatty acid components (14:0,16:0,16:1,18:1 and 20:5),and n-alkanes (C16-C23) were quantified in the samples.Our results indicate that the organic matters were degraded more rapidly in oxic than anoxic conditions.Adsorption of fatty acids onto clay minerals was a rapid and reversible process.Using a simple G model,we calculated the decomposition rate constants for TOC,n-alkanes and fatty acids which ranged from 0.017-0.024 d-1,0.049-0.103 d-1 and 0.011 to 0.069 d-1,respectively.Algal organic matter degraded in two stages characterized by a fast and a slow degradation processes.The addition of clay minerals montmorillonite and kaolinite to the sediments showed significant influence affecting the decomposition processes of algal TOC and fatty acids by adsorption and incorporation of the compounds with clay particles.Adsorption/association of fatty acids by clay minerals was rapid but appeared to be a slow reversible process.In addition to the sediment redox and clay influence,the structure of the compounds also played important roles in affecting their degradation dynamic in sediments.展开更多
基金Supported by the National Natural Science Foundation of China(No.31172388)the 100 Talents Program of the Chinese Academy of Sciencesthe Key Laboratory for Ecological Environment in Coastal Areas(201011),State Oceanic Administration
文摘Thioredoxin (Trx) proteins are involved in many biological processes especially the regulation of cellular redox homeostasis. In this study, two Trx cDNAs were cloned from the mussel Mytilus galloprovincialis using rapid amplification of cDNA ends-polymerase chain reaction (RACE-PCR). The two cDNAs were named MgTrx1 and MgTrx2, respectively. The open reading frames of MgTrx1 and MgTrx2 were 318 and 507 base pairs (bp) and they encoded proteins of 105 and 168 amino acids with estimated molecular masses of 11.45 and 18.93 kDa, respectively. Sequence analysis revealed that both proteins possessed the conserved active site dithiol motif Cys-Gly-Pro-Cys. In addition, MgTrx2 also possessed a putative mitochondrial targeting signal suggesting that it is located in the mitochondria. Quantitative real-time polymerase chain reaction (qPCR) revealed that both MgTrx1 and MgTrx2 were constitutively expressed in all tissues examined. The MgTrx1 transcript was most abundant in hemocytes and gills, whereas the MgTrx2 transcript was most abundant in gonad, hepatopancreas, gill and hemocytes. Following Vibrio anguillarum challenge, the expression of MgTrx1 was up-regulated and reached its peak, at a value 10-fold the initial value, at 24 h. Subsequently, expression returned back to the original level. In contrast, the expression level of MgTrx2 was down-regulated following bacterial stimulation, with one fifth of the control level evident at 12 h post challenge. These results suggest that MgTrx1 and MgTrx2 may play important roles in the response of M. galloprovincialis to bacterial challenge.
基金Supported by the National Natural Science Foundation of China (Nos. 40476038 and 40576039)
文摘A series of laboratory incubation experiments were conducted to examine the decomposition of algal organic matter in clay-enriched marine sediment under oxic and anoxic conditions.During the 245-day incubation period,changes in the concentrations of TOC,major algal fatty acid components (14:0,16:0,16:1,18:1 and 20:5),and n-alkanes (C16-C23) were quantified in the samples.Our results indicate that the organic matters were degraded more rapidly in oxic than anoxic conditions.Adsorption of fatty acids onto clay minerals was a rapid and reversible process.Using a simple G model,we calculated the decomposition rate constants for TOC,n-alkanes and fatty acids which ranged from 0.017-0.024 d-1,0.049-0.103 d-1 and 0.011 to 0.069 d-1,respectively.Algal organic matter degraded in two stages characterized by a fast and a slow degradation processes.The addition of clay minerals montmorillonite and kaolinite to the sediments showed significant influence affecting the decomposition processes of algal TOC and fatty acids by adsorption and incorporation of the compounds with clay particles.Adsorption/association of fatty acids by clay minerals was rapid but appeared to be a slow reversible process.In addition to the sediment redox and clay influence,the structure of the compounds also played important roles in affecting their degradation dynamic in sediments.
