Pleiotropic Role of Rainbow Trout CXCRs in Response to Disease and Environment: Insights from Transcriptional Signatures and Structure Analysis.

Chemokines are cytokines with chemoattractant capacities that exert their physiological functions through the binding of chemokine receptors. Thus, chemokine and receptor complexes exert important roles in regulating development and homeostasis during routine immune surveillance and inflammation. Compared to mammals, the physiology and structure of chemokine receptors in fish have not been systematically studied. Furthermore, the salmonid-specific whole genome duplication has significantly increased the number of functional paralogs of chemokine receptors. In this context, in the current study, trout exhibited 17 cxcr genes, including 12 newly identified and 5 previously identified receptors. Interestingly, gene expression of brain cxcr1 and cxcr4, kidney cxcr3 and cxcr4, and spleen cxcr3, cxcr4, and cxcr5 subtypes were altered by bacterial infection, whereas brain cxcr1, kidney cxcr1 and cxcr7, and liver cxcr2, cxcr3, and cxcr4 subtypes were changed in response to environmental changes. Based on protein structures predicted by ColabFold, the conserved amino acids in binding pockets between trout CXCR4.1 subtypes and human CXCR4 were also analyzed. Our study is valuable from a comparative point of view, providing new insights into the identification and physiology of salmonid chemokine receptors.

Identification, characterization, and transcription of serotonin receptors in rainbow trout (Oncorhynchus mykiss) in response to bacterial infection and salinity changes.

Serotonergic system is involved in the regulation of physiological functions and behavioral traits including cognition, memory, aggression, stress coping, appetite and immunomodulation. Serotonin exerts its functions via binding distinct serotonin receptors which are classified into 7 groups. Salmonid exhibits expanded functional gene copies due to salmonid-specific whole genome duplication. However, serotonin receptor (htr) repertoire is not fully identified in rainbow trout (Oncorhynchus mykiss). In this study, we identified 39 htr genes, including 14 htr1, 4 htr2, 4 htr2 like, 3 htr3, 4 htr4, 2 htr5, 2 htr6, and 6 htr7 subtypes. We investigated physiological functions of serotonin receptors in response to bacterial pathogens exposure and salinity changes. We showed htr1, htr2, htr4 and htr7 subtypes were associated with immunomodulation in response to Vibrio anguillarum or Aeromonas salmonicida infection. Saltwater (salinity of 15) transfer significantly altered htr1, htr2, htr4, and htr7 subtypes, suggesting trout Htr was associated with osmoregulation. We further showed residues interacted with inverse agonist (methiothepin) and serotonin analogue (5-Carboxamidotryptamine) were conserved between trout and human, suggesting exogenous ligands targeting human HTRs might have a role in aquaculture. This study showed duplicated trout Htrs might be physiologically neofunctionalized and potentially exhibit pleiotropic effects in regulating immunomodulation and osmoregulation.

Transcriptome analysis of liver, gill and intestine in rainbow trout (Oncorhynchus mykiss) symptomatically or asymptomatically infected with Vibrio anguillarum.

Rainbow trout (Oncorhynchus mykiss), an important economic cold-water fish worldwide, is severely threatened by viruses and bacteria in the farming industry. The vibriosis outbreak has caused a significant setback to aquaculture. Vibrio anguillarum, one of the common disease-causing vibriosis associated with severe lethal vibriosis in aquaculture, infects fish mainly by adsorption and invasion of the skin, gills, lateral line and intestine. To investigate the defense mechanism of rainbow trout against the pathogen after infection with Vibrio anguillarum, trout were intraperitoneally injected by Vibrio anguillarum and divided into symptomatic group (SG) and asymptomatic group (AG) according to the phenotype. RNA-Seq technology was used to evaluate the transcriptional signatures of liver, gill and intestine of trout injected with Vibrio anguillarum (SG and AG) and corresponding control groups (CG(A) and CG(B)). The GO and KEGG enrichment analyses were used to investigate the mechanisms underlying the differences in susceptibility to Vibrio anguillarum. Results showed that in SG, immunomodulatory genes in the cytokine network were activated and tissue function-related genes were down-regulated, while apoptosis mechanisms were activated. However, AG responded to Vibrio anguillarum infection by activating complement related immune defenses, while metabolism and function related genes were up-regulated. Conclusively, a rapid and effective immune and inflammatory response can successfully defend Vibrio anguillarum infection. However, a sustained inflammatory response can lead to tissue and organ damage and cause death. Our results may provide a theoretical basis for breeding rainbow trout for disease resistance.

Comparison of Dechlorane Plus Concentrations in Sequential Blood Samples of Pregnant Women in Taizhou, China.

To develop an appropriate sampling strategy to assess the intrauterine exposure to dechlorane plus (DP), we investigated DP levels in sequential maternal blood samples collected in three trimesters of pregnancy, respectively, from women living in Taizhou. The median concentration of DPs (sum of syn-DP and anti-DP) in all samples was 30.5 pg g−1 wet-weight and 5.01 ng g−1 lipid-adjusted weight, respectively. The trimester-related DP concentrations were consistently strongly correlated (p < 0.01), indicating that a single measurement of DP levels could represent intrauterine exposure without sampling from the same female repeatedly; however, the wet-weight levels significantly increased across trimesters (p < 0.05), while the lipid-adjusted levels did not significantly vary. Notably, whether lipid-adjusted weight or wet-weight levels, the variation extent of DP across trimesters was found to be less than 41%, and those for other persistent organic pollutants (POPs) reported in the literature were also limited to 100%. The limitation in variation extents indicated that, regardless of the time of blood collection during pregnancy and how the levels were expressed, a single measurement could be extended to screen for exposure risk if necessary. Our study provides different strategies for sampling the maternal blood to serve the requirement for assessment of in utero exposure to DP.

Identification and characterization of mkk genes and their expression profiles in rainbow trout (Oncorhynchus mykiss) symptomatically or asymptomatically infected with Vibrio anguillarum.

Mitogen-activated protein kinase kinases (MKKs) are intermediate kinases of mitogen-activated protein kinases (MAPKs) signaling pathways. MKKs are activated by mitogen-activated protein kinase kinase kinase (MKKK) and then the activated MKKs trigger the activation of downstream MAPKs. MAPK signaling pathways play an important role in regulating immune functions including apoptosis and inflammation. However, studies on identification and characterization of mkk repertoire in rainbow trout (Oncorhynchus mykiss) are still limited. Trout experienced 4 rounds (4R) of whole genome duplication (WGD), thus exhibiting increased paralogs of mkks with potentially functional diversity. In this study, we identified 17 mkk genes in trout and the following bacterial challenge (Vibrio anguillarum) studies showed functional diversity of different mkk subtypes. Vibrio anguillarum infection resulted in significantly up-regulated mkk2 subtypes in spleen and liver, and mkk4b3 in spleen, suggesting immunomodulation was regulated by activation of ERK, p38 and JNK pathways. Compared to other mkk subtypes, mkk6s were down-regulated in symptomatic group, rather than asymptomatic group. The organisms present negative feedback on MAPK activation, thus reducing extra damage to cells. We observed down-regulated mkk6s with up-regulated genes (dusp1 & dusp2) involved in negative feedback of MAPK activation. Based on these results, we might propose the distinct expression patterns of genes associated with MAPK pathways resulted in different phenotypes and symptoms of trout in response to bacterial challenge.

Biopsy of cervical lymph node does not impact the survival of nasopharyngeal carcinoma.

PURPOSE: The optimal practice regarding cervical lymph node biopsy (CLNB) remains to be defined to provide the best clinical management in nasopharyngeal carcinoma (NPC). This study aimed to investigate the effect of CLNB on the survival of NPC patients. METHODS: Patients diagnosed with NPC from 2004 to 2015 were identified using the Surveillance, Epidemiology, and End Results database. Multivariate logistic regression, Kaplan-Meier method, Cox proportional hazards regression analysis, and propensity score matching (PSM) were used to determine the factors associated with CLNB and prognostic effect of CLNB of NPC. RESULTS: We included 1903 patients in this study. There were 321 (16.9%) and 1582 (83.1%) patients with and without CLNB, respectively. The percentage of CLNB was 19.4% in 2004 and was decreased to 8.6% in 2015 (p = 0.044). Patients diagnosed in later years (p = 0.008), older age (p < 0.001), Chinese (p = 0.002), advanced tumor stage (p < 0.001), and early nodal stage (p = 0.003) were less likely to receive additional CLNB. In patients who received additional CLNB, the 5-years NPC-specific survival (NPCSS) was 83.6%, which was similar to patients without CLNB (80.1%, p = 0.159). In addition, a similar 5-years NPCSS was found between those receiving biopsy or aspiration of regional lymph node and those receiving lymph node resection (p = 0.584). There were 187 pairs of patients who were completely matched using PSM, the multivariate prognostic analyses indicated that the receipt of CLNB was not associated with an inferior outcome in the PSM cohort (p = 0.349). Similar results were found after stratification by the year of diagnosis, race/ethnicity, and histology. CONCLUSION: Additional CLNB is not associated with an inferior survival outcome in NPC. Our study provides a reference for the clinical practice of NPC.

Measurement of polychlorinated biphenyls with hand wipes and matched serum collected from Chinese E-waste dismantling workers: Exposure estimates and implications.

To date, dermal/hand-to-mouth exposure to chemicals in the e-waste recycling environment has not been sufficiently understood, and the importance of dermal absorption of chemicals in e-waste dismantling workers remains controversial. In this study, we utilized hand wipes and matched sera to characterize dermal/hand-to-mouth exposure to PCBs for e-waste dismantling workers, and potential effects on thyroid hormones were also assessed. PCB loadings in hand wipes varied from 0.829-265 ng wipe-1 (11.3-2850 ng m-2 wipe-1), with 37.2 ng wipe-1 (432 ng m-2 wipe-1) as the median value. Serum concentrations of PCBs ranged from 32.3-3410 ng g-1 lipid weight (lw) with 364 ng g-1 lw as the median value. Between wipes and sera, lower-chlorinated congeners (e.g. CB-28, -66, -74, -99,-105 and -118) showed significant associations (p < 0.01), but higher-chlorinated congeners (e.g. CB-138, -153, -156, -170, and -180) did not. These lower-chlorinated CBs were the major contributors to estimated dermal/hand-to-mouth average daily doses (ADDs) and the hazard index (HI). Correspondingly, their estimated contributions to serum levels by dermal absorption were also significant, with the contribution of CB-28 being as high as 21.4%. As a consequence, dermal absorption of some low-chlorinated congeners was a non-negligible route for e-waste dismantling workers. Although insignificant association was shown between serum PCBs and thyroid hormones, the potential health risk should be of concern due to the high levels of PCBs observed in workers' sera.

Transcriptional Profiles of Genes Related to Stress and Immune Response in Rainbow Trout (Oncorhynchus mykiss) Symptomatically or Asymptomatically Infected With Vibrio anguillarum.

Rainbow trout (Oncorhynchus mykiss) is one of the most common aquaculture fish species worldwide. Vibriosis disease outbreaks cause significant setbacks to aquaculture. The stress and immune responses are bidirectionally modulated in response to the health challenges. Therefore, an investigation into the regulatory mechanisms of the stress and immune responses in trout is invaluable for identifying potential vibriosis treatments. We investigated the transcriptional profiles of genes associated with stress and trout immune functions after Vibrio anguillarum infection. We compared the control trout (CT, 0.9% saline injection), asymptomatic trout (AT, surviving trout with minor or no symptoms after bacteria injection), and symptomatic trout (ST, moribund trout with severe symptoms after bacteria injection). Our results showed activated immunomodulatory genes in the cytokine network and downregulated glucocorticoid and mineralocorticoid receptors in both AT and ST, indicating activation of the proinflammatory cytokine cascade as a common response in AT and ST. Moreover, the AT specifically activated the complement- and TNF-associated immune defenses in response to V. anguillarum infection. However, the complement and coagulation cascades, as well as steroid hormone homeostasis in ST, were disturbed by V. anguillarum. Our studies provide new insights toward understanding regulatory mechanisms in stress and immune functions in response to diseases.

Arg-Vasotocin Directly Activates Isotocin Receptors and Induces COX2 Expression in Ovoviviparous Guppies.

Oxytocin (OT) is a crucial regulator of reproductive behaviors, including parturition in mammals. Arg-vasopressin (AVP) is a nonapeptide homologous to Arg-vasotocin (AVT) in teleosts that has comparable affinity for the OT receptor. In the present study, ovoviviparous guppies (Poecilia reticulata) were used to study the effect of AVT on delivery mediated by the activation of prostaglandin (PG) biosynthesis via isotocin (IT) receptors (ITRs). One copy each of it and avt and two copies of itrs were identified in guppies. The results of the affinity assay showed that various concentrations of AVT and IT (10-6, 10-7, and 10-8 mol/L) significantly activated itr1 (P < 0.05). In vitro experiments revealed significant upregulation (P < 0.05) of cyclooxygenase 2 (cox2), which is the rate-limiting enzyme involved in PG biosynthesis, and itr1 by AVT and IT. Furthermore, dual in situ hybridization detected positive signals for itr1 and cox2 at the same site, implying that ITR1 may regulate cox2 gene expression. Measurement of prostaglandin F2a (PGF2a) concentrations showed that AVT induced PGF2a synthesis (P < 0.05) and that the effect of IT was not significant. Finally, intraperitoneal administration of PGF2a significantly induced premature parturition of guppies. This study is the first to identify and characterize AVT and ITRs in guppies. The findings suggest that AVT promotes PG biosynthesis via ITR and that PGF2a induces delivery behavior in ovoviviparous guppies.

Identification and characterization of caspases genes in rainbow trout (Oncorhynchus mykiss) and their expression profiles after Aeromonas salmonicida and Vibrio anguillarum infection.

Caspases are highly conserved cysteine-dependent aspartyl-specific proteases that play an important role in regulating cell death and inflammation. However, the caspase genes have not been systematically studied in rainbow trout (Oncorhynchus mykiss). Rainbow trout experienced 4 rounds (4R) of genome duplication in the evolutionary history. Thereby an increased numbers of paralogs are observed in trout, probably with more complicated gene functions. We identified 18 caspase genes in rainbow trout, including two inflammatory caspases (casp1a, casp1b), six apoptosis executioner caspases (casp3, casp3a1, casp3a2, casp3b, casp6, and casp7), nine apoptosis initiator caspases (casp2a, casp2b, casp8, casp9a, casp9b, casp10a, casp10b, casp20a, and casp20b) and one uncategorized caspase gene (casp17). To investigate the potentially physiological functions of caspase genes, we challenged the rainbow trout with Aeromonas salmonicida (A. salmonicida) and Vibrio anguillarum (V. anguillarum). Results showed that the CASP3-regulated intrinsic apoptosis was activated after A. salmonicida infection, while the CASP8 and CASP6-regulated extrinsic apoptosis exerted the greatest effect on trout challenged with V. anguillarum. In response to V. anguillarum infection, the data of RNA-Seq further showed the casp8 was tightly integrated with the significantly enriched Gene Ontology terms and functional pathways, including apoptosis regulation, pathogen detection and immunomodulation. Our study provides a foundation for the physiological functions and regulatory network of the caspase genes in teleosts.

GHRH-SST-GH-IGF axis regulates crosstalk between growth and immunity in rainbow trout (Oncorhynchus mykiss) infected with Vibrio anguillarum.

An energy trade-off is existed between immunological competence and growth. The axis of growth hormone releasing hormone, somatostatin, growth hormone, insulin-like growth factor (GHRH-SST-GH-IGF axis) regulates growth performances and immune competences in rainbow trout (Oncorhynchus mykiss). The salmonid-specific whole genome duplication event is known to result in duplicated copies of several key genes in GHRH-SST-GH-IGF axis. In this study, we evaluated the physiological functions of GHRH-SST-GH-IGF axis in regulating crosstalk between growth and immunity. Based on principal components analysis (PCA), we observed the overall expression profiles of GHRH-SST-GH-IGF axis were significantly altered by Vibrio anguillarum infection. Trout challenged with Vibrio anguillarum showed down-regulated igf1s subtypes and up-regulated igfbp1a1. The brain sst genes (sst1a, sst1b, sst3b and sst5) and igfpbs genes (igfbp4s and igfbp5b2) were significantly affected by V. anguillarum infection, while the igfbp4s, igfbp5s, igfbp6s and igf2bps genes showed significant changes in peripheral immune tissues in response to V. anguillarum infection. Gene enrichment analyses showed functional and signaling pathways associated with apoptosis (such as p53, HIF-1 or FoxO signaling) were activated. We further proposed a possible model that describes the IGF and IGFBPs-regulated interaction between cell growth and programmed death. Our study provided new insights into the physiological functions and potentially regulatory mechanisms of the GHRH-SST-GH-IGF axis, indicating the pleiotropic effects of GHRH-SST-GH-IGF axis in regulating crosstalk between growth and immunity in trout.

Transfer of dechlorane plus between human breast milk and adipose tissue and comparison with legacy lipophilic compounds.

In this study, levels of dechlorane plus (DP) in breast milk and matched adipose tissue samples were measured from 54 women living in Wenling, China. Polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) were measured simultaneously for comparison. The levels of ∑DPs/∑PBDEs varied from less than one to several dozens of ng g-1 lipid weight (lw) in matrices and the levels of ∑PCBs varied between several to hundreds of ng g-1 lw. In the same matrix, ∑DPs and ∑PCBs/∑PBDEs showed a significant relationship (p < 0.05), indicating that they shared common sources. Accordingly, there was a strong association of lipid-adjusted concentrations of individual compounds (BDE-209 excluded) between matrices (p < 0.001), suggesting that breast milk could be a proxy for adipose tissue in human bioburden monitoring of these compounds. The predicted lipid-adjusted milk/adipose ratios varied from 0.62 to 1.5 but showed significant differences (p<0.001) between compounds, suggesting a compound-specific transfer between milk lipids and adipose tissue lipids. Specifically, the milk/adipose ratios for syn-DP and anti-DP (-1.40 and 1.3, respectively) were significantly higher than those of CB congeners and hexa/hepta-BDE congeners (p < 0.05). In addition, unlike PCBs/PBDEs (excluding BDE-209), DP's hydrophobicity might not be responsible for its preferable distribution in milk lipids. Instead, the interaction with nonlipid factors played a key role. The fraction of anti-DP between the two kinds of matrices was not significantly different, suggesting that the biochemical transfer processes may not be efficient enough to distinguish DP isomers. Nevertheless, the congener patterns of PCBs/PBDEs gave a clue about the compound-specific transfer between milk and adipose tissue. To our knowledge, this is the first to report the relationships of DP between adipose tissue and breast milk. These results could provide useful and in-depth information on biomonitoring of DP and facilitate the understanding of the accumulation and excretion potentials of DP and its distribution-related mechanism in humans.

Bioaccumulation and transfer characteristics of dechlorane plus in human adipose tissue and blood stream and the underlying mechanisms.

In this study, bioaccumulation and transfer characteristics of dechlorane plus (DP) were examined between human adipose tissue and matched maternal serum, and the possible transfer mechanism between tissues was further discussed. The median level of total DP was 971 pg g-1 wet weight (ww) and 1.22 ng g-1 lipid weight (lw) in adipose tissue, respectively, and was 34.7 pg g-1 ww and 3.98 ng g-1 lw for serum, respectively. DP wet levels' positive association with fat contents of five types of human tissues indicated that DP distribution might be related to lipid-driven mechanism. However, the lipid-adjusted adipose-serum partitioning ratios were estimated to be 0.35 for syn-DP and 0.35 for anti-DP, accordingly, which implied that the DP distribution between serum and adipose tissues, was not only regulated by the tissue lipid contents. Both the internal mono-dechlorination of anti-DP, and stereo-selective behavior of DP isomers were not found in DP transfer from blood to adipose tissue. The marginal positive relationship was observed between serum levels and apolipoprotein A concentrations (p = 0.095 for total DP and 0.045 for syn-DP), and neither association was found between serum levels and thyroid hormone concentrations (THs). To our best knowledge, this is the first report about the accumulation relationship of DP between human adipose tissue and blood stream with the corresponding distribution-related mechanism.

Environmental hypoxia causes growth retardation, osteoclast differentiation and calcium dyshomeostasis in juvenile rainbow trout (Oncorhynchus mykiss).

Hypoxia generally refers to a dissolved oxygen (DO) level that is less than 2-3 mg/L. With ongoing global warming and environment pollution, environmental or geological studies showed hypoxia frequently occurs in global aquatic systems including ocean, river, estuaries and coasts. A preliminary study was performed to evaluate hypoxia tolerant of rainbow trout (Oncorhynchus mykiss) with parameters of mortality, behavior, endocrine and metabolite, identifying three DO levels including normoxia (Ctrl, 7.0 mg/L), non-lethal hypoxia (NH, 4.5 mg/L) and lethal hypoxia (LH, 3.0 mg/L). Furthermore, trout was treated by Ctrl, NH and LH for six hours to mimic the acute hypoxia in wild and/or farming conditions. A significantly higher mortality was observed in LH group. Trout of NH and LH showed stressful responses with unnormal swimming, increased serum cortisol and up-regulated gill hif1α transcription. Despite trout of NH and LH increased the oxygen delivery abilities by increasing the serum hemoglobin levels, the anerobic metabolism were inevitably observed with increased lactate. This study also showed a prolonged influence of NH and LH on growth after 30-days' recovery. Based on RNA-Seq data, different expression genes (DEGs) associated with stress, apoptosis, antioxidant, chaperone, growth, calcium and vitamin D metabolism were identified. Enrichment analysis showed DEGs were clustered in osteoclast differentiation, apoptosis and intracellular signaling transduction pathways. Results further showed NH and LH significantly decreased bone calcium content and disrupted the growth hormone-insulin-like growth factor (GH-IGF) axis. Our study might contribute to a better understanding of the effects of hypoxia on rainbow trout.

Effects of long-term crowding stress on neuro-endocrine-immune network of rainbow trout (Oncorhynchus mykiss).

Low levels of stresses cause eustress while high stressful situations result in distress. Female rainbow trout (Oncorhynchus mykiss) was reared under crowded conditions to mimic the stressful environment of intensive fishery production. Trout was stocked for 300 days with initial densities of 4.6 ±â€¯0.02 (final: 31.1 ±â€¯0.62), 6.6 ±â€¯0.03 (final: 40.6 ±â€¯0.77), and 8.6 ±â€¯0.04 (final: 49.3 ±â€¯1.09) kg/m3 as SD1, SD2 and SD3. We assessed molecular, cellular and organismal parameters to understand the flexibility of neuro-endocrine-immune network during stress. Trout with higher initial density (SD3) displayed the slightly activated hypothalamus-pituitary-interrenal (HPI) axis with positively increased antioxidant enzyme activities and anti-inflammatory cytokine transcriptions on day 60 or 120. These results indicated that low level of stress was capable of exerting eustress by activating neuro-endocrine-immune network with beneficial adaptation. Transition from eustress to distress was induced by the increased intensity and duration of crowding stress on day 240 and 300. The prolonged activation of HPI axis resulted in suppressed growth hormone-insulin-like growth factor (GH-IGF) axis, up-regulated cytokine transcriptions and severe reactive oxygen species stress. Stress means reset of neuro-endocrine-immune network with energy expenditure and redistribution. Digestive ability of trout with distress was also inhibited on day 240 and 300, indicating a decreased total energy supplement and energy distribution for functions are not necessary for surviving such as growth and reproduction. Consequently, we observed the dyshomeostasis of energy balance and neuro-endocrine-immune network of trout during long-term crowding conditions.

The impact of acute thermal stress on the metabolome of the black rockfish (Sebastes schlegelii).

Acute change in water temperature causes heavy economic losses in the aquaculture industry. The present study investigated the metabolic and molecular effects of acute thermal stress on black rockfish (Sebastes schlegelii). Gas chromatography time-of-flight mass spectrometry (GC-TOF-MS)-based metabolomics was used to investigate the global metabolic response of black rockfish at a high water temperature (27°C), low water temperature (5°C) and normal water temperature (16°C). Metabolites involved in energy metabolism and basic amino acids were significantly increased upon acute exposure to 27°C (P < 0.05), and no change in metabolite levels occurred in the low water temperature group. However, certain fatty acid levels were elevated after cold stress (P < 0.05), and this effect was not observed in the 27°C group, suggesting that acute high and low temperature exposures caused different physiological responses. Using quantitative real-time PCR, we analyzed the expression of ubiquitin (ub), hypoxia-inducible factor (hif), lactate dehydrogenase (ldh), and acetyl-CoA carboxylase (acac). Higher expression levels of ub, hif, and ldh (P < 0.05) were observed in the high water temperature group, but no changes in these expression levels occurred in the low water temperature group. Our findings provide a potential metabolic profile for black rockfish when exposed to acute temperature stress and provide some insights into host metabolic and molecular responses to thermal stress.

14-3-3 gene family in spotted sea bass (Lateolabrax maculatus): Genome-wide identification, phylogenetic analysis and expression profiles after salinity stress.

The tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation (14-3-3) proteins are a group of highly conserved homologous and heterologous proteins involved in a wild range of physiological processes, including the regulation of many molecular phenomena under different environmental salinities. In this study, we identified eleven 14-3-3 genes from the spotted sea bass (Lateolabrax maculatus) genome and transcriptomic databases and verified their identities by conducting phylogenetic, syntenic and gene structure analyses. The spotted sea bass 14-3-3 genes are highly conserved based on sequence alignment, conserved domains and motifs, and tertiary structural feature. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis of 14-3-3 genes in gill of spotted sea bass under normal physiological conditions indicated that the expression level of 14-3-3 zeta was the highest among tested genes, followed by 14-3-3 theta. Furthermore, expression profiles of 14-3-3 genes in gill tissue (in vivo and in vitro) indicated that the 14-3-3 zeta and 14-3-3 theta genes were significantly induced by different environmental salinities in spotted sea bass, suggesting their potential involvement in response to salinity challenge. Our findings may lay the foundation for future functional studies on the 14-3-3 gene family in euryhaline teleosts.

Expression of estrogen receptors in female rainbow trout (Oncorhynchus mykiss) during first ovarian development and under dense rearing condition.

To study the expression of four estrogen receptor genes (erα1, erα2, erß1, erß2) of female rainbow trout (Oncorhynchus mykiss) during first ovarian development, trouts were sampled from different ovarian stages. Serum E2 (estradiol) was measured by ELISA and estrogen receptors mRNA expression were examined by qRT-PCR. Our results showed a close association between increased erα1 and vitellogenin mRNA expression during ovarian maturation and increased erα2 mRNA expression in mature ovarian stages. Correlation analysis revealed that a negative relationship between serum E2 and ovarian erß1 (or hepatic erß2), but ovarian erß2 mRNA expression was relatively unchanged during first ovarian development. Trout were also reared in different densities as stocking density 1, 2 and 3 (SD1, 4.6-31.1 kg/m3; SD2, 6.6-40.6 kg/m3; SD3, 8.6-49.3 kg/m3) to elucidate effects of high density on estrogen receptor expression. Histology observation showed ovarian development of trout in higher densities were retard with a relatively early stage and fewer vitellogenin accumulation. Trout in high densities showed significantly decreased serum E2, erα mRNA expression and increasing trends of erß mRNA expression. A noticeable increase of ovarian erß2 mRNA expression was seen in trout when density is approaching to 50 kg/m3. In conclusion, we may hypothesize that increased erß mRNA expression triggered by high density result in decreased erα mRNA expression and vitellogenesis. As a result, ovarian development in higher densities was retard.

Hypothalamus-pituitary-gonad axis of rainbow trout (Oncorhynchus mykiss) during early ovarian development and under dense rearing condition.

The objective of this study was to determine the hypothalamus-pituitary-gonad (HPG) axis of female rainbow trout (Oncorhynchus mykiss) during early ovarian development and under high rearing density. Trouts were sampled from 240 (ovarian stage II) to 540 (ovarian stage IV) days following hatching (DFH) as control group (Ctrl, 4.6-31.1kg/m(3)) to determine HPG axis during early ovarian development. Trouts from the same batch of fertilized eggs were reared in two higher densities during 240-540 DFH as stocking density 1 and 2 (SD1, 6.6-40.6kg/m(3); SD2, 8.6-49.3kg/m(3)) to elucidate effects of high density on reproductive parameters. Dopamine, E2 (estradiol), 17α,20ß-P (17α,20ß-dihydroxy4-pregnen-3-one) and P4 (progesterone) were evaluated by radioimmunoassay or ELISA. mRNA expression of hypothalamic gnrh-1, -2 (gonadotropin-releasing hormone-1, -2), pituitary gonadotropins (fsh/lh, follicle-stimulating hormone/luteinizing hormone) and their cognate receptors (fshr/lhr) in ovaries were examined by qRT-PCR. Our findings demonstrated mRNA expression of hypothalamic sgnrh-1, pituitary fsh and ovarian fshr increased in early ovarian development (360 DFH). Serum 17α,20ß-P and pituitary lh mRNA expression first increased when trouts were in ovarian stage III (420 DFH). Ovaries were at different stages when reared in different densities. Long-term high density treatment (over 31.7kg/m(3)) resulted in decreased hypothalamic sgnrh-1, pituitary fsh, ovarian fshr, serum E2, and increased hypothalamus gnrh-2 and serum dopamine during vitellogenin synthesis, suggesting HPG of rainbow trout might be retarded under dense rearing condition.

[Study on the effects of nucleating agents on photooxidation degradation of PP by FTIR and IM].

In the present paper, the natural photooxidation degradation behavior and mechanism of PP containing two alpha-nucleating agents (TM-1 and TM-3) and a beta-nucleating agent (TMB-5) were studied by Fourier transform infrared spectroscopy (FTIR) and infrared microscopy (IM) so that helpful instructions would be obtained for the PP material design and applications. The results showed that the nucleating agents had significant impact on the photooxidation stability of PP. The existence of them accelerated the photooxidation reaction of PP to different extents with the rank of PP/TMB-5>PP/TM-3>PP/TM-1>PP. However, the photooxidation procedure and the corresponding oxidative products did not change. The oxidation profiles in PP and nucleated PP bars after exposure had similar trends. The carbonyl index curves had a maximum at the surface and declined gradually with distance from the exposed surface, then decreased to nearly zero at the depth of about 250 microm, which was named as the surface oxidation layer (SOL). The SOL thickness, which was dependent on the transmission of the ultraviolet light, the oxygen diffusion and mostly the "skin" layer formed during the injection moulding, did not change with exposure time. The development of oxidation along the depth coincided with the initiation and propagation of the surface cracks. Before fragments dropped from the seriously oxidized surface, the photooxidation degradation of PP was restricted mainly in the surface oxidation layer.