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【Objective】The effects of different mass concentrations of MS-222 and eugenol stresses on gill and liver tissue damage in juvenile Eleutheronema tetradactylum were studied.【Method】Seven different mass concentrations of MS-222 (20, 30, 35, 40, 45, 50 and 60 mg/L) and seven different mass concentrations of eugenol (5, 10, 20, 25, 30, 40 and 50 mg/L) were set to analyze the static anaesthesia effects of different treatments on juvenile E. tetradactylum with an average length of 4.5 (±0.5) cm and an average body weight of 1.5 (±0.5) g.【Result】When the concentration of MS-222 was not less than 35 mg/ L, the juvenile fish began to show stress reactions after 467 s of anesthesia. When the concentration was 50 mg/L, some juvenile fish could be induced into the anesthesia period. When the concentration was 60 mg/L, all juvenile fish could be induced into the anesthesia period after 293 s. When the concentration of eugenol was not less than 25 mg/L, the juvenile fish began to exhibit stress reactions after 291 s of anaesthesia; when the concentration was 30 mg/L, some juvenile fish could be induced into the anaesthesia period; when the concentrations were 40 and 50 mg/L, all juvenile fish could be induced into the anaesthesia period at 194 s and 102 s, respectively. With the increase of MS-222 and eugenol concentrations, the time for juvenile fish to enter the same anaesthesia period was significantly shortened (P < 0.05). At high concentrations, the time for juvenile fish to enter the anaesthesia period was too fast, which exceeded the tolerance value and may have a certain toxic effect on the fish body, leading to fish death. By observing the pathological sections of juvenile fish tissues, it was found that, with the increase of MS-222 and eugenol concentrations, the liver cells of juvenile fish showed vacuoles, disordered arrangement, nuclear dissolution visible in the nucleus and unclear liver plate structure. The gill lamellae were curved with enlarged ends, and they may burst or fall off in severe cases.【Conclusion】A moderate dosage of anaesthetic can reduce the stress response of fish to the external environment and reduce oxygen consumption. Different concentrations of MS-222 and eugenol (except for 5 mg/L) have a sedative effect on E. tetradactylum within 3 minutes. When the concentrations of the two anaesthetics are too high, the anaesthesia time is too long, and the juvenile fish are in a state of stress for a long time, the fish will die.

【Objective】The effects of different mass concentrations of MS-222 and eugenol stresses on gill and liver tissue damage in juvenile Eleutheronema tetradactylum were studied.【Method】Seven different mass concentrations of MS-222 (20, 30, 35, 40, 45, 50 and 60 mg/L) and seven different mass concentrations of eugenol (5, 10, 20, 25, 30, 40 and 50 mg/L) were set to analyze the static anaesthesia effects of different treatments on juvenile E. tetradactylum with an average length of 4.5 (±0.5) cm and an average body weight of 1.5 (±0.5) g.【Result】When the concentration of MS-222 was not less than 35 mg/ L, the juvenile fish began to show stress reactions after 467 s of anesthesia. When the concentration was 50 mg/L, some juvenile fish could be induced into the anesthesia period. When the concentration was 60 mg/L, all juvenile fish could be induced into the anesthesia period after 293 s. When the concentration of eugenol was not less than 25 mg/L, the juvenile fish began to exhibit stress reactions after 291 s of anaesthesia; when the concentration was 30 mg/L, some juvenile fish could be induced into the anaesthesia period; when the concentrations were 40 and 50 mg/L, all juvenile fish could be induced into the anaesthesia period at 194 s and 102 s, respectively. With the increase of MS-222 and eugenol concentrations, the time for juvenile fish to enter the same anaesthesia period was significantly shortened (P ＜ 0.05). At high concentrations, the time for juvenile fish to enter the anaesthesia period was too fast, which exceeded the tolerance value and may have a certain toxic effect on the fish body, leading to fish death. By observing the pathological sections of juvenile fish tissues, it was found that, with the increase of MS-222 and eugenol concentrations, the liver cells of juvenile fish showed vacuoles, disordered arrangement, nuclear dissolution visible in the nucleus and unclear liver plate structure. The gill lamellae were curved with enlarged ends, and they may burst or fall off in severe cases. 【Conclusion】A moderate dosage of anaesthetic can reduce the stress response of fish to the external environment and reduce oxygen consumption. Different concentrations of MS-222 and eugenol (except for 5 mg/L) have a sedative effect on E. tetradactylum within 3 minutes. When the concentrations of the two anaesthetics are too high, the anaesthesia time is too long, and the juvenile fish are in a state of stress for a long time, the fish will die [ABSTRACT FROM AUTHOR]

Adaptation to environmental variation caused by global climate change is a significant aspect of fisheries management and ecology. A reduction in ocean salinity is visible in near-shore areas, especially in the Baltic Sea, where it is affecting the Atlantic cod population. Cod is one of the most significant teleost species, with high ecological and economical value worldwide. The population of cod in the Baltic Sea has been traditionally divided into two subpopulations (western and eastern) existing in higher- and lower-salinity waters, respectively. In recent decades, both Baltic cod subpopulations have declined massively. One of the reasons for the poor condition of cod in the Baltic Sea is environmental factors, including salinity. Thus, in this study, an oligonucleotide microarray was applied to explore differences between Baltic cod subpopulations in response to salinity fluctuations. For this purpose, an exposure experiment was conducted consisting of salinity elevation and reduction, and gene expression was measured in gill tissue. We found 400 differentially expressed genes (DEGs) involved in the immune response, metabolism, programmed cell death, cytoskeleton, and extracellular matrix that showed a subpopulation-dependent pattern. These findings indicate that osmoregulation in Baltic cod is a complex process, and that western and eastern Baltic cod subpopulations respond differently to salinity changes. [ABSTRACT FROM AUTHOR]

Abstract Background Maintaining osmotic equilibrium plays an important role in the survival of cold-water fishes. Heat stress has been proven to reduce the activity of Na+/K+-ATPase in the gill tissue, leading to destruction of the osmotic equilibrium. However, the mechanism of megatemperature affecting gill osmoregulation has not been fully elucidated. Results In this study, Siberian sturgeon (Acipenser baerii) was used to analyze histopathological change, plasma ion level, and transcriptome of gill tissue subjected to 20℃, 24℃and 28℃. The results showed that ROS level and damage were increased in gill tissue with the increasing of heat stress temperature. Plasma Cl− level at 28℃ was distinctly lower than that at 20℃ and 24℃, while no significant difference was found in Na+ and K+ ion levels among different groups. Transcriptome analysis displayed that osmoregulation-, DNA-repair- and apoptosis-related terms or pathways were enriched in GO and KEGG analysis. Moreover, 194 osmoregulation-related genes were identified. Amongst, the expression of genes limiting ion outflow, occluding (OCLN), and ion absorption, solute carrier family 4, member 2 (AE2) solute carrier family 9, member 3 (NHE3) chloride channel 2 (CLC-2) were increased, while Na+/K+-ATPase alpha (NKA-a) expression was decreased after heat stress. Conclusions This study reveals for the first time that the effect of heat stress on damage and osmotic regulation in gill tissue of cold-water fishes. Heat stress increases the permeability of fish’s gill tissue, and induces the gill tissue to keep ion balance through active ion absorption and passive ion outflow. Our study will contribute to research of global-warming-caused effects on cold-water fishes.

Background: Maintaining osmotic equilibrium plays an important role in the survival of cold-water fishes. Heat stress has been proven to reduce the activity of Na+/K+-ATPase in the gill tissue, leading to destruction of the osmotic equilibrium. However, the mechanism of megatemperature affecting gill osmoregulation has not been fully elucidated. Results: In this study, Siberian sturgeon (Acipenser baerii) was used to analyze histopathological change, plasma ion level, and transcriptome of gill tissue subjected to 20℃, 24℃and 28℃. The results showed that ROS level and damage were increased in gill tissue with the increasing of heat stress temperature. Plasma Cl− level at 28℃ was distinctly lower than that at 20℃ and 24℃, while no significant difference was found in Na+ and K+ ion levels among different groups. Transcriptome analysis displayed that osmoregulation-, DNA-repair- and apoptosis-related terms or pathways were enriched in GO and KEGG analysis. Moreover, 194 osmoregulation-related genes were identified. Amongst, the expression of genes limiting ion outflow, occluding (OCLN), and ion absorption, solute carrier family 4, member 2 (AE2) solute carrier family 9, member 3 (NHE3) chloride channel 2 (CLC-2) were increased, while Na+/K+-ATPase alpha (NKA-a) expression was decreased after heat stress. Conclusions: This study reveals for the first time that the effect of heat stress on damage and osmotic regulation in gill tissue of cold-water fishes. Heat stress increases the permeability of fish's gill tissue, and induces the gill tissue to keep ion balance through active ion absorption and passive ion outflow. Our study will contribute to research of global-warming-caused effects on cold-water fishes. [ABSTRACT FROM AUTHOR]

Adaptation to environmental variation caused by global climate change is a significant aspect of fisheries management and ecology. A reduction in ocean salinity is visible in near-shore areas, especially in the Baltic Sea, where it is affecting the Atlantic cod population. Cod is one of the most significant teleost species, with high ecological and economical value worldwide. The population of cod in the Baltic Sea has been traditionally divided into two subpopulations (western and eastern) existing in higher- and lower-salinity waters, respectively. In recent decades, both Baltic cod subpopulations have declined massively. One of the reasons for the poor condition of cod in the Baltic Sea is environmental factors, including salinity. Thus, in this study, an oligonucleotide microarray was applied to explore differences between Baltic cod subpopulations in response to salinity fluctuations. For this purpose, an exposure experiment was conducted consisting of salinity elevation and reduction, and gene expression was measured in gill tissue. We found 400 differentially expressed genes (DEGs) involved in the immune response, metabolism, programmed cell death, cytoskeleton, and extracellular matrix that showed a subpopulation-dependent pattern. These findings indicate that osmoregulation in Baltic cod is a complex process, and that western and eastern Baltic cod subpopulations respond differently to salinity changes.

Salinity can affect the physiological and productive characteristics of bivalves. The razor clam Sinonovacula constricta naturally distributing in intertidal zones and estuarine waters is extensively cultured in China. High-salinity is a serious threat to its culture, especially in pond culture model. Here, we investigated the effects of high-salinity on the survival, gill tissue, enzyme activity and free amino acid content of S. constricta. Individuals were randomly divided into six groups treated with different salinities of 20, 25, 30, 35, 40, and 45 ppt. The median lethal salinity calculated by linear regression and probit analysis methods were similar, with 46.61, 43.17, 36.99, 35.99, and 34.99 ppt by linear regression, while 44.63, 42.87, 38.45, 37.32, and 36.17 ppt by probit analysis at 72, 96, 120, 144, and 168 h, respectively. Furthermore, paraffin section revealed that the gill of razor clam shrunk quickly under high-salinity and dissolved at 48 h under salinity of 40 ppt, but not under 30 ppt. In addition, the activities of three enzymes including Na+-K+-ATPase, acid phosphatase and alkaline phosphatase changed significantly under high-salinity. Besides, the contents of total free amino acids (TFAAs) in the gill tissues were 61.25 ± 1.58, 89.36 ± 4.18, and 111.98 ± 1.46 mg⋅g–1 at salinity of 20, 30, and 40 ppt, respectively, indicating increasing TFAA contents with salinity. Notably, several amino acid species including taurine, alanine, proline, glycine and glutamic showed significantly changed contents in response to salinity variation, suggesting these amino acids might play an important role in razor clam’s adaptation to salinity stress. Combining all these results, it was referred that razor clams may adapt to moderately high-salinity of 30 ppt in a short time through osmotic adjustment. Although a small proportion of individuals could survive under the salinity of 35 ppt, the death of most individuals still suggested it can hardly be accepted in aquacultural production. Notably, living under a salinity of 40 ppt for more than 48 h could cause great damage to razor clams. Therefore, the seawater salinity is recommended to be lower than 30 ppt for S. constricta aquaculture. Overall, this study provides guidance for the culture and breeding of high-salinity tolerant razor clams.

The Ichthyophthirius multifiliis is one of the most important protozoan pathogens of farmed and wild fish populations. In this study, histopathological effects of gamma-irradiated trophonts of I. multifiliis coated with alginate nanoparticles in rainbow trout gill were evaluated. Therefore, after adaption period the fish with mean weight 30 g were distributed to 4 groups: Two groups were treated with gamma-irradiated trophonts of I. multifiliis and coated with alginate nanoparticles, gamma-irradiated trophonts of I. multifiliis. One group was infected with active trophonts of parasite as positive control. In negative control group, no treatment was used. On day 30, gill tissue from treated, infected and control fish was analyzed for evaluating the histopathological alterations. The results showed that the use of alginate nanoparticles formulated in gamma-irradiated I. multifilis trophonts can significantly decrease severe hyperplasia, sub-epithelial edema, and fusion of the secondary lamellae, focal and multifocal necrosi in gill. Also, gamma-irradiated trophonts of I. multifiliis coated with alginate nanoparticles induced an increase in amount of the gill macrophages in treated fish. Therefore, the alginate nanoparticles can be in leading development of safe and efficient gamma-irraditad trophonts deliver tool in rainbow trout with more useful behavior and fewer side effects on gill tissue.

One hundred and five fish with an average weight of 2.5 g from the aquaculture center in the port of Turkmen, Golestan province, were cached, sub-lethal test was for 1 week with 5 treated of diazinon as 0, 25, 50, 75 and 90% of LC50 (0, 0.42, 0.85, 1.28 and 1.17 ppm, respectively). The results showed that with progress of poison, gill tissue lesions will be increased such as hyperemia and hemorrhage, fractures and secondary lamellar connection, one-way and two-way lamellar cast gill and shorten the secondary lamellar, swollen, multicellular be harder to lamella.

Here, we aimed to investigate potential effects of ocean acidification on antimicrobial peptide (AMP) activity in the gills of Mytilus edulis , as gills are directly facing seawater and the changing pH (predicted to be reduced from ∼8.1 to ∼7.7 by 2100). The AMP activity of gill and haemocyte extracts was compared at pH 6.0, 7.7 and 8.1, with a radial diffusion assay against Escherichia coli . The activity of the gill extracts was not affected by pH, while it was significantly reduced with increasing pH in the haemocyte extracts. Gill extracts were also tested against different species of Vibrio ( V. parahaemolyticus , V. tubiashii , V. splendidus , V. alginolyticus ) at pH 7.7 and 8.1. The metabolic activity of the bacteria decreased by ∼65–90%, depending on species of bacteria, but was, as in the radial diffusion assay, not affected by pH. The results indicated that AMPs from gills are efficient in a broad pH-range. However, when mussels were pre-exposed for pH 7.7 for four month the gill extracts presented significantly lower inhibit of bacterial growth. A full in-depth proteome investigation of gill extracts, using LC-Orbitrap MS/MS technique, showed that among previously described AMPs from haemocytes of Mytilus , myticin A was found up-regulated in response to lipopolysaccharide, 3 h post injection. Sporadic occurrence of other immune related peptides/proteins also pointed to a rapid response (0.5–3 h p.i.). Altogether, our results indicate that the gills of blue mussels constitute an important first line defence adapted to act at the pH of seawater. The antimicrobial activity of the gills is however modulated when mussels are under the pressure of ocean acidification, which may give future advantages for invading pathogens. [ABSTRACT FROM AUTHOR]

Mussel ( Mytilus galloprovincialis (Lamarck, 1819)) is directly exposed to sea water contamination that elicits significant physiological and cellular response, although its extent mounted in aquaculture-reared in comparison to wild bivalve populations is scarcely known. Therefore, we have compared contamination biomarkers in mussels from reared (Marina farm) and wild, anthropogenically affected site (Vranjic Bay). While predictably, the levels of metals (Cu, Cd, Pb, Zn, Fe, and Hg) in whole bivalve tissues determined by atomic absorption spectrophotometry resulted in significantly higher concentrations in wild mussels, accompanied by elevated number of apoptotic cells in gills, the activity of multixenobiotic resistance defense mechanism (MXR), measured as the accumulation rate of model substrate rhodamine B (RB) gave contrasting results. The functional RB assay evidenced a lower MXR efflux activity in the gill tissue of wild mussels, indicating two possible scenarios that will need further focus: (1) persisting sea water pollution increased cell damage of bivalve gill cells and consequently led to leakage of the RB into cytoplasm and dysfunctional MXR efflux in wild mussels; or/and (2) a mixture of different toxic compounds present in Vranjic Bay sea water induced oversaturation of MXR efflux, inducing elevated accumulation of the dye. Consequently, it seems that an efficient physiological functioning of MXR in wild mussels is strongly hampered by existence of an unknown quantity of sea water pollutants that may endanger intrinsic organismal defense system and lead toward the enhancement of toxicity. [ABSTRACT FROM AUTHOR]

Caffeine, a biologically active drug with many known molecular targets, is recognized as a contaminant of marine systems. Although the concentrations of caffeine reported from aquatic systems are low (ng/l-μg/l), harmful ecological effects not detected by traditional toxicity tests could occur as a result of caffeine contamination. We used Hsp70, a molecular biomarker of cellular stress, to investigate the sub-lethal cellular toxicity of environmentally relevant concentrations of caffeine on the mussel Mytilus californianus, a dominant species in the rocky intertidal zone along the Oregon Coast. Hsp70 concentrations in the gill and mantle tissue of mussels exposed to 0.05, 0.2, and 0.5 μg/l of caffeine for 10, 20, and 30 days were compared to basal levels in control mussels. Hsp70 in the gill tissue of M. californianus had an initial attenuation of the stress protein followed by a significant up-regulation relative to controls in all but the 0.5 μg/l treatment. Hsp70 in the mantle tissue of mussels exposed to caffeine did not differ from control mussels. This study provides laboratory evidence that environmentally relevant concentrations of caffeine can exert an effect on M. californianus gill tissue at the molecular-level. [ABSTRACT FROM AUTHOR]

Background: Bathymodiolus azoricus is a deep-sea hydrothermal vent mussel found in association with large faunal communities living in chemosynthetic environments at the bottom of the sea floor near the Azores Islands. Investigation of the exceptional physiological reactions that vent mussels have adopted in their habitat, including responses to environmental microbes, remains a difficult challenge for deep-sea biologists. In an attempt to reveal genes potentially involved in the deep-sea mussel innate immunity we carried out a high-throughput sequence analysis of freshly collected B. azoricus transcriptome using gills tissues as the primary source of immune transcripts given its strategic role in filtering the surrounding waterborne potentially infectious microorganisms. Additionally, a substantial EST data set was produced and from which a comprehensive collection of genes coding for putative proteins was organized in a dedicated database, "DeepSeaVent" the first deep-sea vent animal transcriptome database based on the 454 pyrosequencing technology. Results: A normalized cDNA library from gills tissue was sequenced in a full 454 GS-FLX run, producing 778,996 sequencing reads. Assembly of the high quality reads resulted in 75,407 contigs of which 3,071 were singletons. A total of 39,425 transcripts were conceptually translated into amino-sequences of which 22,023 matched known proteins in the NCBI non-redundant protein database, 15,839 revealed conserved protein domains through InterPro functional classification and 9,584 were assigned with Gene Ontology terms. Queries conducted within the database enabled the identification of genes putatively involved in immune and inflammatory reactions which had not been previously evidenced in the vent mussel. Their physical counterpart was confirmed by semi-quantitative quantitative Reverse-Transcription-Polymerase Chain Reactions (RT-PCR) and their RNA transcription level by quantitative PCR (qPCR) experiments. Conclusions: We have established the first tissue transcriptional analysis of a deep-sea hydrothermal vent animal and generated a searchable catalog of genes that provides a direct method of identifying and retrieving vast numbers of novel coding sequences which can be applied in gene expression profiling experiments from a non-conventional model organism. This provides the most comprehensive sequence resource for identifying novel genes currently available for a deep-sea vent organism, in particular, genes putatively involved in immune and inflammatory reactions in vent mussels. The characterization of the B. azoricus transcriptome will facilitate research into biological processes underlying physiological adaptations to hydrothermal vent environments and will provide a basis for expanding our understanding of genes putatively involved in adaptations processes during post-capture long term acclimatization experiments, at "sea-level" conditions, using B. azoricus as a model organism. [ABSTRACT FROM AUTHOR]

In the present study, we developed a two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) technique for examining the response of the proteome from gill tissue of Paralichthys olivaceus (POGT) to acute cadmium (AC) toxicity. Approximately 700 protein spots were detected from the gill sample when applying a 600μg protein 2D-PAGE gel in the pH range 5.0–8.0, and approximately 400 of these were identified by peptide mass fingerprinting (PMF) and database search. Compared to a control sample, significant changes were visualized in 18 protein spots exposed to seawater cadmium acute toxicity at 10.0ppm for 24h. Among these spots, two were up-regulated, one was down-regulated, seven showed low expression, and eight showed high expression. The collected spots were further identified by PMF and database search. Ten of the 18 proteins identified on the 2D-PAGE gel, including heat shock protein 70 and calcium-binding protein, demonstrated a synchronous response to AC, and we suggest that the variable levels and trends of these spots on the gel might be utilized as biomarker profiles to investigate cadmium contamination levels in seawater and to evaluate the degree of risk of human fatalities. The experimental results emphasize that the application of multiple biomarkers has an advantage over single biomarkers for monitoring levels of heavy metal contamination in seawater. [Copyright &y& Elsevier]

Abstract: Two partial mRNA sequences predicted to encode anti-lipopolysaccharide factors (ALFs) were identified among expressed sequence tags generated from the American lobster Homarus americanus and complete cDNA sequences were obtained from library clones. Comparison of the translated amino acid sequences to those publicly available confirmed similarity to arthropod anti-lipopolysaccharide factors. Both protein sequences, designated ALFHa-1 and ALFHa-2, contained an N-terminal signal peptide and two half-cysteines participating in a disulfide bridge, features conserved in other ALFs. Predicted secondary structures were similar to that described for the ALF from the horseshoe crab Limulus polyphemus. As part of an exploratory study of immunity in H. americanus, lobsters were injected with the bacterium Vibrio fluvialis and gill, hematopoietic, and hepatopancreas tissues were sampled for analysis of gene expression of ALFHa-1 and ALFHa-2 by quantitative PCR. The relative abundance of ALFHa-2 mRNA was not significantly affected by Vibrio injection in any of the three tissues tested. In contrast, ALFHa-1 mRNA levels in gills were increased by the treatment some 17-fold. Our results support a molecularly specific regulation of antimicrobial proteins in response to bacterial infection in H. americanus. [Copyright &y& Elsevier]

A group of tyrosinase isoforms with isoelectric points between 4.9 and 5.2 was isolated from gill tissue of Portabella mushrooms. Use of protease inhibitors was not able to increase the amount of latent forms significantly in crude extracts or to preserve latent tyrosinase activity during purification. The tyrosinase in gill tissue extracts showed latent activity above pH 5.5 and suppressed or displayed no latent activity below pH 5.5 when assayed in the presence of SDS. The purified isoforms showed monophenolase activity toward 4-hydroxyanisole but practically no activity toward tyrosine or tyramine. The purified isoforms showed greater activity toward catechol than either 4-methylcatechol, dopa, dopamine, chlorogenic acid, t-butylcatechol, or catechin. The Km for catechol was similar for the group of isolated isoforms (4.3 mM) compared to the isoforms in crude extracts (5.3 mM). Crude extracts showed several isoforms ranging from 50 to 230 kDa after partially denaturing SDS PAGE, while the purified isoforms showed molecular weights of 70 kDa. [Copyright &y& Elsevier]