Interleukin-33 Predicts Poor Prognosis and Promotes Renal Cell Carcinoma Cell Growth Through its Receptor ST2 and the JNK Signaling Pathway.

BACKGROUND/AIMS: Renal cell carcinoma (RCC) is currently the ninth most common cancer in men. Interleukin (IL)-33 expression has previously been associated with a number of cancers; however, its biological role in RCC is poorly understood. In this study, we sought to elucidate the role of IL-33 in RCC. METHODS: Serum IL-33 levels were measured by ELISA. IL-33 expression in clinical RCC samples was examined by immunocytochemistry. The proliferation and apoptosis rate of RCC were determined by CCK8 and flow cytometry. Mcl1 and Bcl-2 expression were measured by quantitative real-time PCR and western blotting. JNK expression were measured by western blotting and flow cytometry. The in vivo role of IL-33 in RCC tumorigenesis was examined by animal models. RESULTS: We found that increased expression of IL-33 in RCC was associated with tumor-lymph node-metastasis (TNM) stage and inversely correlated with prognosis. IL-33 enhances RCC cell growth in vivo and stimulates RCC cell proliferation and prevents chemotherapy-induced tumor apoptosis in vitro. Furthermore, we demonstrated that IL-33 promotes RCC cell proliferation and chemotherapy resistance via its receptor ST2 and the JNK signaling activation in tumor cells. CONCLUSION: Our findings suggest that targeting IL-33/ST2 and JNK signaling may have potential value in the treatment of RCC.

The association of plasma fibrinogen with clinicopathological features and prognosis in esophageal cancer patients.

BACKGROUND: Numerous studies have shown that plasma fibrinogen was linked to esophageal cancer (EC) risk. However, the clinical significance of plasma fibrinogen in EC patients remain unclear and need to be further clarified. RESULTS: A total of 2865 patients with EC from 11 published studies were included in this meta-analysis. The prognostic and clinical relevance of plasma fibrinogen were evaluated in EC patients. Statistical significance of the pooled hazard ratio (HR) was found for overall survival (OS), disease free survival (DFS) and recurrence-free survival (RFS) in EC. Subgroup analyses for OS were also performed to confirm the prognostic value of plasma fibrinogen. Additionally, the overall results indicated that elevated plasma fibrinogen was significantly associated with tumor invasion, lymph node metastasis (LNM) and clinical stage. MATERIALS AND METHODS: A comprehensive literature retrieval was performed in PubMed, Embase, Cochrane database, Web of science and Chinese National Knowledge Infrastructure (CNKI) and Wanfang databases to identify relevant studies published prior to April 15, 2017. CONCLUSIONS: Elevated plasma fibrinogen could be served as a promising biomarker for predicting a poor prognosis and unfavorable clinicopathologic features for EC.

Pre-acclimation to low copper mitigated immunotoxic effects in spleen and head-kidney of large yellow croaker (Pseudosciaena crocea) when exposed subsequently to high copper.

The hypothesis tested in this study was that Cu pre-acclimation would mitigate high Cu induced immunotoxic effects in large yellow croaker Pseudosciaena crocea. To the end, fish were pre-acclimation to 0 and 84µg CuL-1 for 48h and then exposed to 0 and 420µg CuL-1 for another 48h. Survival rate, Cu content, ROS, NO, activities and mRNA levels of inflammatory genes (iNOS and COX-2), and gene expressions of transcription factor NF-κB and its inhibitor IκBα were determined in spleen and head-kidney of large yellow croaker. Cu pre-acclimation significantly reduced mortality of fish exposed to 420µg CuL-1. Cu pre-acclimation triggered the up-regulation of both enzyme activities and express levels of iNOS and COX-2 in spleen under 420µg CuL-1 exposure, resulting in remarkable reduction of Cu content and ROS in this tissue. Contrast to spleen, iNOS activity remained unchanged but the mRNA level of iNOS increased, and the mRNA level of COX-2 remained constant though COX-2 activity enhanced in head-kidney, suggesting iNOS and COX-2 may be modulated by Cu at a post-transcriptional level. In this process, NF-κB/IκBα signaling molecules may play a vital role in the transcriptional activation of inflammatory genes in both spleen and head-kidney. In conclusion, low Cu pre-acclimation alleviated high Cu induced immunotoxicity in spleen and head-kidney of large yellow croaker by enhancing the activities and mRNA levels of inflammatory genes.

Abrupt salinity stress induces oxidative stress via the Nrf2-Keap1 signaling pathway in large yellow croaker Pseudosciaena crocea.

The aim of the present study was to evaluate the effects of abrupt salinity stress (12, 26 (control), and 40) on lipid peroxidation, activities and mRNA levels of antioxidant enzymes (Cu/Zn-SOD, CAT, GPx, and GR), and gene expression of the Nrf2-Keap1 signaling molecules at different times (6, 12, 24, and 48 h) in the liver of large yellow croaker Pseudosciaena crocea. The results showed that lipid peroxidation was sharply reduced at 6 h and increased at 12 h before returning to control levels in the hypo-salinity group. Similarly, lipid peroxidation was significantly decreased at 6 h followed by a sharp increase towards the end of the exposure in the hyper-salinity group. Negative relationships between lipid peroxidation and antioxidant enzyme activities and positive relationships between activities and gene expression of antioxidant enzymes were observed, suggesting that the changes at molecular levels and enzyme activity levels may provide protective roles against damage from salinity stress. Obtained results also showed a coordinated transcriptional regulation of antioxidant genes, suggesting that Nrf2 is required for regulating these genes. Furthermore, there was a positive relationship between the mRNA levels of Nrf2 and Keap1, indicating that Keap1 plays an important role in switching off the Nrf2 response. In conclusion, this is the first study to elucidate effects of salinity stress on antioxidant responses in large yellow croaker through the Keap1-Nrf2 pathway.

Immunosuppressive effects and associated compensatory responses in zebrafish after full life-cycle exposure to environmentally relevant concentrations of cadmium.

In natural environments, fish survive in polluted water by cadmium (Cd) throughout their whole life cycle. However, little information is available on Cd toxicity considering a life cycle assessment. The present study investigated effects of environmental levels of cadmium (0, 2.5, and 5µg/L) on immune responses in liver and spleen of zebrafish for 15 weeks, from embryos to sexually maturity. Nitric oxide (NO) levels and iNOS activity declined in liver and spleen of zebrafish exposed to 5µg/L Cd, suggesting an immunosuppressive effect. The result was further supported by the decreased transcriptional levels of proinflammatory cytokines by Cd, such as interleukin-6 (IL-6), interleukin-10 (IL-10), interleukin-1ß (IL-1ß), and tumour necrosis factor-α (TNF-α) in liver. However, a sharp increase in the mRNA levels of these cytokines was observed in spleen of zebrafish exposed to Cd. The increased mRNA expression of these proinflammatory cytokines may be the secondary effect following immunosuppression and just reflect a compensatory mechanism for coping with the decreased immunity, which may explain an increase in mRNA levels and a decrease in iNOS activity in spleen of zebrafish exposed to Cd. In liver, the down-regulated mRNA levels of iNOS paralleled with the decreased iNOS activity, suggesting a synchronous response from a molecular level to a biochemical level. Positive correlations between mRNA expression levels of nuclear transcription factor κB (NF-κB) and proinflammatory cytokines were also observed, suggesting that NF-κB might be required for the protracted induction of inflammatory genes. The corresponding changes in the mRNA levels of the inhibitor of κBα (IκBαa and IκBαb) may form a feedback loop to restore transcriptional activity of NF-κB. Furthermore, splenic ROS levels were increased by 5µg/L Cd, possibly activating NF-κB pathway. Taken together, immunosuppressive effects and tissue-dependent compensatory responses were demonstrated in zebrafish after full life-cycle exposure to environmental levels of Cd, indicating a compromise between survival and immunity.

Negative effect of chronic cadmium exposure on growth, histology, ultrastructure, antioxidant and innate immune responses in the liver of zebrafish: Preventive role of blue light emitting diodes.

The present study explored the possible preventive effects of blue light emitting diodes (LEDs) on cadmium (Cd)-induced oxidative stress and immunotoxicity in zebrafish. To this end, zebrafish were exposed to a white fluorescent bulb or blue LEDs (LDB, peak at 450nm, at an irradiance of 0.9W/m2), and 0 or 30µgL-1 waterborne Cd for 5 weeks. Growth performance, survival rate, and hepatic histology, ultrastructure, antioxidant and innate immune responses were determined in zebrafish. Cd exposure alone reduced growth and survival rate, and induced oxidative damage and changes in histology and ultrastructure. However, Cd exposure in combination with LDB apparently relieved these negative effects. The alleviation of adverse effects might result from the up-regulation of antioxidant and innate immune genes at transcriptional, translational, or post-translational levels. Cd exposure alone dramatically enhanced mRNA levels of nuclear transcription factor κB (NF-κB) and E2-related factor (Nrf2). However, compared to Cd exposure alone, Cd exposure in combination with LDB apparently down-regulated both genes. Taken together, our results suggest that chronic Cd exposure induced a negative effect on zebrafish, possibly involved in NF-κB-induced immunotoxicity and Nrf2-induced oxidative stress. Finally, for the first time, our data demonstrated that LDB could protect fish against Cd toxicity.

Organ-specific effects of low-dose zinc pre-exposure on high-dose zinc induced mitochondrial dysfunction in large yellow croaker Pseudosciaena crocea.

The study was carried out to evaluate the effects of low-dose zinc (Zn) pre-exposure on survival rate, new Zn accumulation, and mitochondrial bioenergetics in the liver and spleen of large yellow croaker exposed to high-dose Zn. To the end, fish were pre-exposed to 0 and 2 mg L-1 Zn for 48 h and post-exposed to 0 and 12 mg L-1 Zn for 48 h. Twelve milligrams Zn per liter exposure alone reduced survival rate, but the effect did not appear in the 2 mg L-1 Zn pre-exposure groups. Two milligrams per liter Zn pre-exposure also ameliorated 12 mg Zn L-1 induced new Zn accumulation, reactive oxygen species (ROS) levels, and mitochondrial swelling in the liver. However, these effects did not appear in the spleen. In the liver, 2 mg L-1 Zn pre-exposure apparently relieved 12 mg L-1 Zn induced down-regulation of activities of ATP synthase (F-ATPase), succinate dehydrogenase (SDH), and malate dehydrogenase (MDH). The mRNA levels of these genes remained relatively stable in fish exposed to 12 mg L-1 Zn alone, but increased in fish exposed to 12 mg L-1 Zn with 2 mg L-1 Zn pre-treatment. In the spleen, 2 mg Zn L-1 pre-exposure did not mitigate the down-regulation of mRNA levels of genes and activities of relative enzymes induced by 12 mg L-1 Zn. In conclusion, our study demonstrated low-dose zinc pre-exposure ameliorated high-dose zinc induced mitochondrial dysfunction in the liver but not in the spleen of large yellow croaker, indicating an organ-specific effect.

Different effects of low- and high-dose waterborne zinc on Zn accumulation, ROS levels, oxidative damage and antioxidant responses in the liver of large yellow croaker Pseudosciaena crocea.

The aim of the present study was to assess survival rate, Zn accumulation, reactive oxygen species (ROS) levels, oxidative damage and antioxidant responses after Zn exposure (2 and 8 mg L-1 Zn) at different exposure times (6, 12, 24, 48 and 96 h) in the liver of large yellow croaker. Survival rate was reduced at 96 h, and hepatic Zn content increased during 24-96 by 8 mg L-1 Zn. In the 2 mg L-1 Zn group, no fish died and the increase in Zn content merely occurred at 96 h. Exposure to 8 mg L-1 Zn induced accumulation of ROS, lipid peroxidation and protein carbonylation during the late stage of exposure. In contrast, exposure to 2 mg L-1 Zn did not result in oxidative damage, which may result from the up-regulation of antioxidant defenses. Although exposure to 8 mg L-1 Zn increased activities and mRNA levels of antioxidant enzymes during the early stage of exposure, including Cu/Zn-SOD, Mn-SOD, CAT, GPx and GR, the activities of these enzymes except Cu/Zn-SOD were inhibited at 96 h. Furthermore, a sharp increase in Nrf2 expression was observed in fish exposed to 8 mg L-1 at 6 and 12 h, and 2 mg L-1 at 12 h and 24 h, suggesting that Nrf2 was required for the protracted induction of these genes. The late increase in Keap1 expression may support its role in switching off the Nrf2 response. In conclusion, the present study demonstrated different effects of low- and high-dose waterborne Zn on antioxidant responses, which could contribute to the understanding of antioxidant and toxic roles of zinc on a molecular level.

Circadian time-dependent antioxidant and inflammatory responses to acute cadmium exposure in the brain of zebrafish.

Up to date, little information is available on effects of circadian rhythm on metal-induced toxicity in fish. In this study, zebrafish were acutely exposed to 0.97mgL-1 cadmium for 12h either at ZT0 (the light intensity began to reached maximum) or at ZT12 (light intensity began to reached minimum) to evaluate the temporal sensitivity of oxidative stress and inflammatory responses in the brain of zebrafish. Profiles of responses of some genes at mRNA, protein and activity levels were different between ZT0 and ZT12 in the normal water. Exposure to Cd induced contrary antioxidant responses and similar inflammatory responses between ZT0 and ZT12. However, the number of inflammatory genes which were up-regulated was significantly greater at ZT12 than at ZT0. And, the up-regulated inflammatory genes were more responsive at ZT12 than at ZT0. At ZT12, antioxidant genes were down-regulated at mRNA, protein and activity levels. Contrarily, antioxidant genes were not affected at mRNA levels but activated at the protein and/or activity levels at ZT0. Reactive oxygen species (ROS) sharply increased and remained relatively stable when fish were exposed to Cd at ZT12 and ZT0, respectively. Positive correlations between ROS levels and mRNA levels of nuclear transcription factor κB (NF-κB) and between mRNA levels of NF-κB and its target genes were observed, suggesting that ROS may play an essential role in regulating the magnitude of inflammatory responses. Taken together, oxidative stress and immunotoxicity in the brain were more serious when fish were exposed to Cd in the evening than in the morning, highlighting the importance of circadian rhythm in Cd-induced neurotoxicity in fish.

Acute exposure to waterborne cadmium induced oxidative stress and immunotoxicity in the brain, ovary and liver of zebrafish (Danio rerio).

Cadmium (Cd) is an environmental contaminant that poses serious risks to aquatic organisms and their associated ecosystem. The mechanisms underlying Cd-induced oxidative stress and immunotoxicity in fish remain largely unknown. In this study, adult female zebrafish were exposed to 0 (control), 1mgL-1 Cd for 24h and 96h, and the oxidative stress and inflammatory responses induced by Cd were evaluated in the brain, liver and ovary. Reactive oxygen species (ROS), nitric oxide (NO), and malondialdehyde (MDA) increased in a time-dependent manner after treatment with Cd in the brain and liver. The increase may result from the disturbance of genes including copper and zinc superoxide dismutase (Cu/Zn-SOD), catalase (CAT), inducible nitric oxide synthase (iNOS), and ciclooxigenase-2 (COX-2) at mRNA, protein and activity levels. Although ROS, NO and MDA were not significantly affected by Cd in the ovary, the up-regulation of Cu/Zn-SOD, CAT, iNOS, and COX-2 was observed. Exposure to Cd induced a sharp increase in the protein levels of tumor necrosis factor alpha (TNF-α) in the brain, liver and ovary, possibly contributing to activate inflammatory responses. Furthermore, we also found a dramatic increase in mRNA levels of NF-E2-related factor 2 (Nrf2) and nuclear transcription factor κB (NF-κB) at 24h in the liver and ovary. The corresponding changes in the mRNA levels of Kelch-like-ECH-associated protein 1 (Keap1a and Keap1b) and the inhibitor of κBα (IκBαa and IκBαb) may contribute to regulate the transcriptional activity of Nrf2 and NF-κB, respectively. Contrarily, mRNA levels of Nrf2, NF-κB, Keap1, Keap1b, IκBαa and IκBαb remained stable at 24 and 96h in the brain. Taken together, we demonstrated Cd-induced oxidative stress and immunotoxicity in fish, possibly through transcriptional regulation of Nrf2 and NF-κB and gene modifications at transcriptional, translational, post-translational levels, which would greatly extend our understanding on the Cd toxicity.

The role of Nrf2/Keap1 signaling in inorganic mercury induced oxidative stress in the liver of large yellow croaker Pseudosciaena crocea.

The aim of the present study was to evaluate the effects of acute inorganic Hg exposure (0, 32 and 64µgHgL(-1)) on lipid peroxidation, activities and gene expression of antioxidant enzymes (Cu/Zn-SOD, CAT, GPx, GR and GST), and mRNA levels of the Keap1-Nrf2 signaling molecules at different exposure times (6h, 12h, 24h, 48h, and 96h) in the liver of large yellow croaker Pseudosciaena crocea. The results showed that lipid peroxidation was sharply reduced by 32µg Hg L(-1) during 6-12h before returning to control levels. Similarly, lipid peroxidation was significantly reduced during 6-12h followed by a sharp increase towards the end of the exposure in the 64µgHgL(-1) group. There was a negative relationship between lipid peroxidation and antioxidant enzyme activities, and positive relationship between activities and gene expression of antioxidant enzymes, suggesting that the changes at a molecular level may underlie enzymatic level and accordingly affect hepatic lipid peroxidation. Obtained results also showed a coordinated transcriptional regulation of antioxidant genes, suggesting that Nrf2 is required for the protracted induction of these genes. Furthermore, a negative relationship between the mRNA levels of Nrf2 and Keap1 indicated that Keap1 may play an important role in switching off the Nrf2 response. In conclusion, this is the first study to elucidate effects of waterborne Hg on antioxidant system in large yellow croaker through the Keap1-Nrf2 pathway, which will aid our understanding of the molecular mechanisms of waterborne heavy metal on antioxidant responses in fish.

Identification and Expression Profile of the Gonadotropin-Releasing Hormone Receptor in Common Chinese Cuttlefish, Sepiella japonica.

Gonadotropin-releasing hormone (GnRH) plays a vital role in the regulation of reproduction through interaction with a specific receptor (the GnRH receptor). In this study, the GnRH receptor gene from the cuttlefish Sepiella japonica (SjGnRHR) was identified and characterized. The cloned full-length SjGnRHR cDNA was 1,468 bp long and contained a 1,029 bp open reading frame encoding 342 amino acid residues, 8 bp of 5' untranslated regions (UTR), and 431 bp of 3' UTR. The putative protein was predicted to have a molecular weight of 38.75 kDa and an isoelectric point of 9.47. In addition, this protein was identified as belonging to the rhodopsin-type (class A) G protein-coupled receptor family. The predicted amino acid sequence contained two N-linked glycosylation sites and 18 phosphorylation sites. Multiple sequence alignment, phylogenetic tree analysis, and three-dimensional structure modeling were conducted to clarify SjGnRHR bioinformatics characteristics. In vitro SjGnRHR expression was carried out using HEK293 cells and the pEGFP-N1 plasmid, to verify the transmembrane properties of this protein. The interaction between the S. japonica GnRH receptor and its ligand was clarified using internalization analysis. SjGnRHR transcriptional quantification confirmed the wide distribution of SjGnRHR in various S. japonica mature tissues. In addition, the transcriptional profile of SjGnRHR in the female brain and ovary during gonadal development was analyzed. Results indicate that GnRHR may be involved in diverse S. japonica physiological functions, especially in the control of reproduction.

Positive and negative innate immune responses in zebrafish under light emitting diodes conditions.

Certain light emitting diodes (LEDs) have become popular in fish farming beacause of a promoting effect on growth and reproduction. However, little information is available on innate immune responses in related tissues under LEDs conditions. The present study assessed the effects of a white fluorescent bulb (the control) and two different light-emitting diodes (LEDs: blue, LDB, peak at 450 nm; red, LDR, 630 nm) on growth and innate immune responses in the serum, liver and ovary of zebrafish for 8 weeks. LDB significantly enhanced specific growth rate (SGR), food intake (FI), and serum globulin levels. In contrast, LDR sharply inhibited SGR, FI, and the levels of albumin and globulin. Under LDB condition, there was an increase in protein levels of alkaline phophatase (AKP) and protein and activity levels of lysozyme (LZM) in the liver, and the levels of mRNA, protein, and activity of LZM in the ovary. Under LDR condition, LZM was dramatically down-regulated at mRNA, protein and activity levels in the ovary, suggesting that LZM was regulated at a transcriptional level. In the liver of the LDR group, though AKP mRNA levels sharply increased, its protein and activity levels significantly declined, indicating that AKP was regulated at translational level. Furthermore, a positive correlation between transcription factor NF-κB RelA mRNA levels and expression levels of AKP and LZM was observed in the liver and ovary, implying a transcriptional regulation of NF-κB RelA. In conclusion, the present study demonstrated a positive effect of LDB and negative effect of LDR on fish growth and innate immune responses, possibly associated with modifications at transcriptional, translational, and post-translational levels, and the transcriptional regulation of the NF-κB signaling molecule.

Molecular characterization and expression analysis of AMPK α subunit isoform genes from Scophthalmus maximus responding to salinity stress.

AMP-activated protein kinase (AMPK) is a highly conserved and multi-functional protein kinase that plays important roles in both intracellular energy balance and cellular stress response. In the present study, molecular characterization, tissue distribution and gene expression levels of the AMPK α1 and α2 genes from turbot (Scophthalmus maximus) under salinity stress are described. The complete coding regions of the AMPK α1 and α2 genes were isolated from turbot through degenerate primers in combination with RACE using muscle cDNA. The complete coding regions of AMPK α1 (1722 bp) and α2 (1674 bp) encoded 573 and 557 amino acids peptides, respectively. Multiple alignments, structural analysis and phylogenetic tree construction indicated that S. maximus AMPK α1 and α2 shared a high amino acid identity with other species, especially fish. AMPK α1 and α2 genes could be detected in all tested tissues, indicating that they are constitutively expressed. Salinity challenges significantly altered the gene expression levels of AMPK α1 and α2 mRNA in a salinity- and time-dependent manners in S. maximus gill tissues, suggesting that AMPK α1 and α2 played important roles in mediating the salinity stress in S. maximus. The expression levels of AMPK α1 and α2 mRNA were a positive correlation with gill Na+, K+-ATPase activities. These findings will aid our understanding of the molecular mechanism of juvenile turbot in response to environmental salinity changes.

Chronic waterborne zinc and cadmium exposures induced different responses towards oxidative stress in the liver of zebrafish.

Based on the same toxic level of 0.6% LC50 for 96-h and the severe situation of water pollution, we compared effects of chronic Zn (180µgL(-1)) and Cd exposures (30µgL(-1)) on growth, survival, histology, ultrastructure, and oxidative stress in the liver of zebrafish for 5 weeks. Growth performance and survival rate remained relatively constant under Zn stress, but was reduced under Cd exposure. Cd exposure also induced severe pyknotic nuclei, evident ultrastructure damage, and considerable lipid inclusions in the hepatocytes. However, these phenomena were not pronounced under Zn exposure. The negative effects caused by Cd may be explained by an increase in hepatic oxidative damage, as reflected by the enhanced levels of lipid peroxidation (LPO) and protein carbonylation (PC). The reduced activity of Cu/Zn-superoxide dismutase (Cu/Zn-SOD) and catalase (CAT) may result in the enhanced hepatic oxidative damage, though the mRNA and protein levels of both genes increased and remained unchanged respectively. On the contrary, Zn up-regulated the levels of mRNA, protein and activity of Cu/Zn-SOD, which may contribute to the decreased LPO levels. Nonetheless, the sharply up-regulated mRNA levels of CAT did not induce an increase in the protein and activity levels of CAT under Zn stress. Furthermore, transcription factor NF-E2-related factor 2 (Nrf2) expression parelleled with its target genes, suggesting that Nrf2 is required for the protracted induction of antioxidant genes. In conclusion, our data demonstrated that essential and non-essential metals induced some differences in oxidative damage in fish. The differences were not caused by the transcriptional level of related genes but depended on post-transcriptional modifications.

Effects of ß-glucan on ROS production and energy metabolism in yellow croaker (Pseudosciaena crocea) under acute hypoxic stress.

The aim of the present study was to evaluate the effect of ß-glucan on acute hypoxia-induced oxidative stress and the changes in energy metabolism by determining ROS production, activities and mRNA levels of energy metabolism enzyme (PK, F-ATPase, SDH and MDH), and in gene expression of HIF-1α in the liver of large yellow croaker. Fish were injected with ß-glucan at a dose of 0 or 5 mg kg(-1) body weight on 6, 4 and 2 days before exposed to 1.5 and 7.0 mg DO L(-1) for 48 h. The results showed that ß-glucan enhanced survival rate and reduced ROS during the lethal hypoxic stress, indicating that ß-glucan could ameliorate hypoxia-induced oxidative stress. Obtained results also showed that ß-glucan could up-regulate activities and mRNA levels of PK, demonstrating that ß-glucan increased anaerobic glycolysis capacity. Furthermore, a coordinated transcriptional regulation of energy metabolism enzyme genes was observed, suggesting that HIF-1α is required for regulating these genes. In conclusion, ß-glucan could alleviate cute hypoxia-induced oxidative stress in large yellow croker by enhancing anaerobic glycolysis capacity, emphasizing a central role of transcription factor HIF-1α in the process.

Cloning, Characterization, and Expression Profile of Estrogen Receptor in Common Chinese Cuttlefish, Sepiella japonica.

Sex steroid hormones are widely detected in molluscs and play important roles in sex determination, gonadal tissue maturation, and gametogenesis. Nevertheless, the signaling pathways of sex steroids in cephalopod have not yet been clearly elucidated. In the present study, a full-length sequence encoding the estrogen receptor (ER) was isolated from common Chinese cuttlefish, Sepiella japonica. The sjER cDNA clone was found to contain 1,788 nucleotides including a 1,470 bp open reading frame encoding 489 amino acid (aa) residues. The deduced ER protein consisted of six nuclear receptor characteristic domains. Based on a phylogenetic analysis, the ER DNA-binding domain and ligand-binding domain are highly conserved compared to other mollusc ERs. Highest aa identities were found for sjER with common octopus (Octopus vulgaris) ER (89%) and pacific oyster (Crassostrea gigas) ER (61%). Tissue expression analysis confirmed that sjER was widely distributed among tissues and predominantly expressed in the brain, liver, gonad (testis and ovary), and other accessory sexual gland (nidamental gland). The ER expression was temporally upregulated in the brain, liver, and ovary during the early sexual maturation period in S. japonica, which is coincident with the fluctuation of ovary estradiol content. These suggest that sjER may be involved in regulating the reproductive cycle of S. japonica. A fusion protein transient transfections assay showed that sjER was mainly located in the nucleus, suggesting a possible orthodox working mechanism of S. japonica ER in the nucleus through a ligand-dependent activation of specific gene transcription.

Antioxidant defenses at transcriptional and enzymatic levels and gene expression of Nrf2-Keap1 signaling molecules in response to acute zinc exposure in the spleen of the large yellow croaker Pseudosciaena crocea.

We evaluated the effects of acute Zn exposure (4 and 8 mg L(-1) Zn) on lipid peroxidation, and activities and mRNA levels of antioxidant enzyme genes (Cu/Zn-SOD, CAT, GPx, and GR), and gene expression of the Nrf2-Keap1 signaling molecule at different exposure times (0, 6, 12, 24, 48, and 96 h) in the spleen of large yellow croaker. Lipid peroxidation remained relatively constant during 6-48 h and 6-24 h and sharply increased at 96 h and during 48-96 h in fish exposed to 4 and 8 mg L(-1) Zn, respectively. Activities of all tested enzymes increased during the early stage of exposure and decreased towards the end of the exposure in both groups. However, mRNA levels of antioxidant enzyme genes were dramatically up-regulated by 4 and 8 mg L(-1) Zn during the late stage of exposure. During the early stage of exposure for 6 h, the 8 mg L(-1) Zn exposure sharply increased mRNA levels of Cu/Zn-SOD, CAT, GPx1b, Nrf2, and Keap1, whereas, the 4 mg L(-1) Zn exposure did not significantly affect the expression of these genes. Our data also showed positive relationships between Nrf2 expression and mRNA levels of its target genes, suggesting that Nrf2 was required for the protracted induction of these genes. Furthermore, a sharp increase in Keap1 expression levels was observed in fish exposed to 4 mg L(-1) at 96 h, and 8 mg L(-1) at 6, 48, and 96 h. In conclusion, the present study demonstrated that Zn-induced antioxidant defenses were involved in modifications at enzymatic and transcriptional levels and the transcriptional regulation of the Nrf2-Keap1 signaling molecule; these results may contribute to the understanding of mechanisms that maintain the correct redox balance in the immune organ of the large yellow croaker.

Zinc acclimation mitigated high zinc induced oxidative stress by enhancing antioxidant defenses in large yellow croaker Pseudosciaena crocea.

The hypothesis tested in the present study was that Zn acclimation will alleviate high Zn induced oxidative stress in large yellow croaker Pseudosciaena crocea. To the end, fish were pre-exposed to 0 and 2mgZnL(-1) for 48h and then exposed to 0 and 10mgZnL(-1) for 48h. Lipid peroxidation, activities and mRNA levels of antioxidant enzyme genes (Cu/Zn-SOD, CAT, GPx and GR), and gene expressions of Nrf2-Keap1 signaling molecules at different exposure time (12h, 24h and 48h) were determined in the liver and spleen of large yellow croaker. 10mgZnL(-1) exposure alone enhanced lipid peroxidation in the liver during 12-48h and in the spleen during 24-48h. Although 2mgZnL(-1) pre-exposure did not affect lipid peroxidation, 2mgZnL(-1) pre-exposure mitigated high Zn induced oxidative stress. The positive effect of Zn acclimation could be attributed to the up-regulated expression and activities of antioxidant enzyme genes under high Zn stress. Obtained results also showed a coordinated transcriptional regulation of antioxidant genes, suggesting that Nrf2 is required for the protracted induction of these genes. Besides, the sharp increase in Keap1 expression levels would support its role in switching off Nrf2 response. In conclusion, Zn acclimation mitigated high Zn-induced oxidative stress in large yellow croker, emphasizing a central role of transcription factor Nrf2 in the process.