A potential microRNA regulation of immune-related genes in invertebrate haemocytes

Dysregulated proinflammatory cytokines and immune-related miRNAs in ASK cells exposed to 17⍺-Ethynyl estradiol and 4-nonylphenol

Endocrine Disruptor Compounds (EDCs) in the aquatic environment have acquired pronounced relevance due to their toxic effect on the aquatic flora and fauna. Xenoestrogens are EDCs that possess estrogenic activity and, thus, disrupt normal estrogen signaling, affecting different functions, such as immune system processes. Two relevant xenoestrogens discarded into fresh and seawater are 4-nonylphenol (NP) and 17⍺-Ethynyl Estradiol (EE2). Considering that the piscicultures of Salmo salar can be located at sites of potential exposure to xenoestrogen-containing effluxes, it is crucial to understand the effect of xenoestrogens on the immune response and its possible molecular mechanism in this species. Our studies reveal an increase in the expression of the receptor era and erb at early times of exposure, a disrupted expression of pro-inflammatory cytokines (il1b and tnfa), an upregulation of ssa-miR-146a-5p, ssa-miR-125 b-5p, and downregulation of ssa-miR-145-5p in ASK cells exposed to estrogen and xenoestrogen, could potentially lead to new strategies for mitigating the effects of xenoestrogens on Salmo salar immune response.

Transcriptomic analysis reveals interactive effects of polyvinyl chloride microplastics and cadmium on Mytilus galloprovincialis: Insights into non-coding RNA responses and environmental implications

Despite increasing concerns regarding the interactions of microplastic and heavy metal pollution, there is limited knowledge on the molecular responses of marine organisms to these stressors. In this study, we used whole-transcriptome sequencing to investigate the molecular responses of the ecologically and economically important bivalve Mytilus galloprovincialis to individual and combined exposures of environmentally relevant concentrations of PVC microplastics and cadmium (Cd). Our results revealed distinct transcriptional changes in M. galloprovincialis, with significant overlap in the differentially expressed genes between the individual and combined exposure groups. Genes involved in cellular senescence, oxidative stress, and galactose metabolism were differentially expressed. Additionally, key signaling pathways related to apoptosis and drug metabolism were significantly modulated. Notably, the interaction of PVC microplastics and Cd resulted in differential expression of genes involved in drug metabolism and longevity regulating compared to single exposures. This suggests that the interaction between these two stressors may have amplified effects on mussel health. Overall, this comprehensive transcriptomic analysis provides valuable insights into the adaptive and detrimental responses of M. galloprovincialis to PVC microplastics and Cd in the environment.

Research Progress on Micro (Nano)Plastics Exposure-Induced miRNA-Mediated Biotoxicity

Micro- and nano-plastics (MNPs) are ubiquitously distributed in the environment, infiltrate organisms through multiple pathways, and accumulate, thus posing potential threats to human health. MNP exposure elicits changes in microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs), thereby precipitating immune, neurological, and other toxic effects. The investigation of MNP exposure and its effect on miRNA expression has garnered increasing attention. Following MNP exposure, circRNAs serve as miRNA sponges by modulating gene expression, while lncRNAs function as competing endogenous RNAs (ceRNAs) by fine-tuning target gene expression and consequently impacting protein translation and physiological processes in cells. Dysregulated miRNA expression mediates mitochondrial dysfunction, inflammation, and oxidative stress, thereby increasing the risk of neurodegenerative diseases, cardiovascular diseases, and cancer. This tract, blood, urine, feces, placenta, and review delves into the biotoxicity arising from dysregulated miRNA expression due to MNP exposure and addresses the challenges encountered in this field. This study provides novel insights into the connections between MNPs and disease risk.

Synergistic modulation of neuroendocrine-inflammation pathway by microRNAs facilitates intertidal adaptation of molluscs

Neuroendocrine-immune system is an evolution-conserved regulatory network in maintaining the homeostasis of animals. While knowledge on the roles of neuroendocrine-immune system in the disease and stress responses of organisms is growing, the ecological roles of neuroendocrine-immune system, especially how it shapes the unique lifestyle of organisms remain insufficiently investigated. As an endemic and dominant mollusc in intertidal region, oysters have evolved with a primitive neuroendocrine-immune system and with a sessile lifestyle. Recently, a novel neuroendocrine-immune pathway, Ca2+/calmodulin (CaM)-nitrite oxide synthase (NOS)/nitrite oxide (NO)-tumor necrosis factor (TNF) pathway, is identified in oysters and found altered dynamically during aerial exposure, one common but challenging stresses for intertidal organisms and a decisive factor shaping their habitat. Since the pathway proves fatal in prolonged aerial exposure, we hypothesized that the activation/deactivation of pathway could be strictly modulated in adaptation to the sessile lifestyle of oysters. Here, a synergistic modulation on the Ca2+/CaM-NOS/NO-TNF pathway by four members of miR-92 family and two oyster-specific miRNAs was identified, which further hallmarks the resilience and survival strategy of oysters to aerial exposure. Briefly, these six miRNAs were down-regulating CgCaM24243 post-transcriptionally and deactivating the pathway during the early-stage of stress. However, a robust recession of these miRNAs occurred at the late-stage of stress, resulting in the reactivation of pathway and overwhelming accumulation of cytokines. These results demonstrated a complicated interaction between miRNAs and ancient neuroendocrine-immune system, which facilitates the environmental adaptation of intertidal oysters and provides novel insight on the function and evolution of neuroendocrine-immune system in ecological context.

Short-term in vitro exposure of Pinctada imbricata's haemocytes to Quaternium-15: exploring physiological and cellular responses

Since the 2000s, the pearl oyster Pinctada imbricata (Röding, 1798) has become established along the transitional waterways of the "Capo Peloro Lagoon" natural reserve, where it is now abundant due to its adaptability to different hydrological, climatic, environmental, and pollution conditions. This study aims to evaluate haemocyte immune-mediated responses in vitro to quaternium-15, a common pollutant in aquatic ecosystems. Cell viability and phagocytosis activity decreased when exposed to 0.1 or 1mg/L of quaternium-15. Moreover, decreasing phagocytosis was confirmed by gene expression modulation of actin, involved in cytoskeleton rearrangement. Effects on oxidative stress-related genes were also assessed (Cat, MnSod, Zn/CuSod, GPx). The qPCR data revealed alterations in antioxidant responses through gene dose- and time-dependent modulation. This study presents insights into the physiological responses and cellular mechanisms of P. imbricata haemocytes to environmental stressors, indicating that this species is useful as a novel bioindicator for future toxicological studies.

Combined effects of temperature rise and sodium lauryl sulfate in the Mediterranean mussel

Personal care products (PCPs) are those compounds used daily (e.g., soaps, shampoos, deodorants, and toothpaste), explaining their frequent detection in aquatic systems. Still, scarce information is available on their effects on inhabiting wildlife. Among the most commonly used PCPs is the surfactant Sodium Lauryl Sulfate (SLS). The present study investigated the influence of temperature (CTL 17 ºC vs 22 ºC) on the effects of SLS (0 mg/L vs 4 mg/L) in the mussel species Mytilus galloprovincialis. Mussels' general health status was investigated, assessing their metabolic and oxidative stress responses. Higher biochemical alterations were observed in SLS-exposed mussels and warming enhanced the impacts, namely in terms of biotransformation capacity and loss of redox homeostasis, which may result in consequences to population maintenance, especially if under additional environmental stressors. These results confirm M. galloprovincialis as an excellent bioindicator of PCPs pollution, and the need to consider actual and predicted climate changes.

Hemocyte coagulation and phagocytic behavior in early stages of injury in crayfish (Arthropoda: Decapoda) affect their morphology

Crustacean hemocytes are important mediators of immune functions such as coagulation and phagocytosis. We employed an in situ approach to investigate the ultrastructural behavior of hemocytes during coagulation and phagocytosis in the early stages after injury caused by leg amputation, using transmission electron microscopy technique in marbled crayfish Procambarus virginalis. Hemocytes underwent drastic morphological changes during coagulation. The morphology of the cytoplasmic granules changed from electron-dense to electron-lucent forms in an expanding manner. The transformed granules containing amorphous electron-lucent material were observed to merge and discharge their contents into extracellular space for coagulation. We also observed that the contents of the nucleus participate in the process of coagulation. In addition, leg amputation induced extensive muscle degeneration and necrotic tissues were avidly taken up by the phagocytic hemocytes containing distinct phagosomes. Interestingly, we observed for the first time how the digested contents of phagocytized necrotic tissues are incorporated into granules and other cellular components that change the cell morphology by increasing the granularity of the hemocytes. Nevertheless, the degranulation of hemocytes during coagulation can also reduce their granularity. Given that morphological traits are important criteria for hemocyte classification, these morphological changes that occur during coagulation and phagocytosis must be taken into account.

Exploring the Role of a Novel Interleukin-17 Homolog from Invertebrate Marine Mussel Mytilus coruscus in Innate Immune Response: Is Negative Regulation by Mc-Novel_miR_145 the Key?

Interleukin-17 (IL-17) represents a class of proinflammatory cytokines involved in chronic inflammatory and degenerative disorders. Prior to this study, it was predicted that an IL-17 homolog could be targeted by Mc-novel_miR_145 to participate in the immune response of Mytilus coruscus. This study employed a variety of molecular and cell biology research methods to explore the association between Mc-novel_miR_145 and IL-17 homolog and their immunomodulatory effects. The bioinformatics prediction confirmed the affiliation of the IL-17 homolog with the mussel IL-17 family, followed by quantitative real-time PCR assays (qPCR) to demonstrate that McIL-17-3 was highly expressed in immune-associated tissues and responded to bacterial challenges. Results from luciferase reporter assays confirmed the potential of McIL-17-3 to activate downstream NF-κb and its targeting by Mc-novel_miR_145 in HEK293 cells. The study also produced McIL-17-3 antiserum and found that Mc-novel_miR_145 negatively regulates McIL-17-3 via western blotting and qPCR assays. Furthermore, flow cytometry analysis indicated that Mc-novel_miR_145 negatively regulated McIL-17-3 to alleviate LPS-induced apoptosis. Collectively, the current results showed that McIL-17-3 played an important role in molluscan immune defense against bacterial attack. Furthermore, McIL-17-3 was negatively regulated by Mc-novel_miR_145 to participate in LPS-induced apoptosis. Our findings provide new insights into noncoding RNA regulation in invertebrate models.

Effects of environmental factors on the cellular and molecular parameters of the immune system in decapods

Crustaceans and in particular decapods (i.e. shrimp, crabs and lobsters) are a diverse, commercially and ecologically important group of organisms. They are exposed to a range of environmental factors whose abiotic and biotic components are prone to fluctuate beyond their optimum ranges and, in doing so, affect crustaceans' immune system and health. Changes in key environmental factors such as temperature, pH, salinity, dissolved oxygen, ammonia concentrations and pathogens can provoke stress and immune responses due to alterations in immune parameters. The mechanisms through which stressors mediate effects on immune parameters are not fully understood in decapods. Improved knowledge of the environmental factors - above all, their abiotic components - that influence the immune parameters of decapods could help mitigate or constrain their harmful effects that adversely affect the production of decapod crustaceans. The first part of this overview examines current knowledge and information gaps regarding the basic components and functions of the innate immune system of decapods. In the second part, we discuss various mechanisms provoked by environmental factors and categorize cellular and molecular immune responses to each environmental factor with special reference to decapods.

Comparative transcriptome analysis reveals immunotoxicology induced by three organic UV filters in Manila clam (Ruditapes philippinarum)

Benzophenone-3 (BP-3), 4-methyl-benzylidene camphor (4-MBC) and 2-ethyl-hexyl-4-trimethoxycinnamate (EHMC) are commonly used organic ultraviolet (UV) filters and are frequently detected in water environments. In the present study, we studied the potential adverse impacts of UV filter exposures in Ruditapes philippinarum by investigating transcriptomic profiles and non-specific immune enzyme activities. Transcriptome analysis showed that more genes were differentially regulated in EHMC-treated group, and down-regulated genes (2009) were significantly more than up-regulated ones (410) at day 7. Function annotation revealed that pathways "immune system", "cell growth and death" and "infectious diseases" were significantly enriched. Generally, combined qPCR and biochemical analyses demonstrated that short-term exposure to low dose of UV filters could activate immune responses, whereas the immune system would be restrained after prolonged exposure. Taken together, the present study firstly demonstrated the immunotoxicology induced by BP-3, 4-MBC and EHMC on R. philippinarum, indicating their potential threats to the survival of marine bivalves.

Integrative analysis of the miRNA-mRNA regulation network in hemocytes of Penaeus vannamei following Vibrio alginolyticus infection

Penaeus vannamei is an important cultured shrimp that has high commercial value in the worldwide. However, the industry suffers heavy economic losses each year due to disease outbreaks caused by pathogenic bacteria. In the present study, after Vibrio alginolyticus infection, DNA damage in the hemocytes of the shrimp markedly increased, and autophagy and apoptosis increased significantly. Subsequently, hemocytes were sampled from the control and infected shrimp and sequenced for mRNA and microRNA (miRNA) 24 h after V. alginolyticus infection to better understand the response mechanism to bacterial infection in P. vannamei. We identified 1,874 and 263 differentially expressed mRNAs (DEGs) and miRNAs (DEMs) respectively, and predicted that 997 DEGs were targeted by DEMs. These DEGs were involved in the regulation of multiple signalling pathways, such as Toll and IMD signalling, TGF-beta signalling, MAPK signalling, and cell apoptosis, during Vibrio alginolyticus infection of the shrimp. We identified numerous mRNA-miRNA interactions, which provide insight into the defense mechanism that occur during the antimicrobial process of P. vannamei.

Glyphosate exposure modulates lipid composition, histo-architecture and oxidative stress status and induces neurotoxicity in the smooth scallop Flexopecten glaber

Glyphosate is the most sprayed pesticide across the globe. Its toxicity to non-target marine organisms has recently piqued the scientific community's interest. Therefore, the purpose of this study is to investigate the potentially toxic effects of glyphosate on scallops, an ecologically and economically important bivalve group. To do that, specimens of the smooth scallop Flexopecten glaber were exposed to different concentrations (10, 100, and 1000 μg L-1) of the technical-grade glyphosate acid (GLY) for 96 h. The detrimental effects of this pollutant were assayed at cellular and tissular levels. The obtained results showed that the GLY was able to induce oxidative stress in the gills and the digestive gland of F. glaber as revealed by the enhanced hydrogen peroxide (H2O2), protein carbonyls (PCO), malondialdehyde (MDA), and lipid peroxides (LOOH) levels and the altered antioxidant defense system (the glutathione GSH content and the superoxide dismutase (SOD) activity). Additionally, GLY was found to alter the fatty acid profile, to exert a neurotoxic effect through the inhibition of the acetylcholinesterase (AChE) activity, and to provoke several histopathological damages in the two organs studied. The obtained results revealed that the pure form of GLY may exert toxic effects on F. glaber even at relatively low concentrations.

Triclosan induced zebrafish immunotoxicity by targeting miR-19a and its gene socs3b to activate IL-6/STAT3 signaling pathway

As a broad-spectrum antibacterial agent, triclosan (TCS) has been confirmed to possess potential immunotoxicity to organisms, but the underlying mechanisms remains unclear. Herein, with the aid of transgenic zebrafish strains Tg (coro1A: EGFP) and Tg (rag2: DsRed), we intuitively observed acute TCS exposure caused the drastic differentiation, abnormal development and distribution of innate immune cells, as well as barriers to formation of adaptive immune T cells. These abnormalities implied occurrence of the cytokine storm, which was further evidenced by expression changes of immune-related genes, and functional biomarkers. Based on transcriptome deep sequencing, target gene prediction and dual luciferase validation, the highly conservative and up-regulated miR-19a was chosen as the research target. Under TCS exposure, miR-19a up-regulation triggered down-regulation of its target gene socs3b, and simultaneously activated the downstream IL-6/STAT3 signaling pathway. Artificial over-expression and knock-down of miR-19a was realized by microinjecting agomir and antagomir, respectively, in 1-2-cell embryos. The miR-19a up-regulation inhibited socs3b expression to activate IL-6/STAT3 pathway, and yielded abnormal changes in the functional cytokine biomarkers, along with the sharp activation of immune responses. These findings disclose the molecular mechanisms regarding TCS-induced immunotoxicity, and offer important theoretical guidance for healthy safety evaluation and disease early warning from TCS pollution.

Impact of phthalates and bisphenols plasticizers on haemocyte immune function of aquatic invertebrates: A review on physiological, biochemical, and genomic aspects

The invertebrate innate immunity is a crucial characteristic that represents a valuable basis for studying common biological responses to environmental pollutants. Cell defence mechanisms are key players in protecting the organism from infections and foreign materials. Many haemocyte-associated immunological parameters have been reported to be immunologically sensitive to aquatic toxins (natural or artificial). Environmental plastic pollution poses a global threat to ecosystems and human health due to plastic vast and extensive use as additives in various consumer products. In recent years, studies have been done to evaluate the effects of plasticizers on humans and the environment, and their transmission and presence in water, air, and indoor dust, and so forth. Hence, the development of biomarkers that evaluate biological responses to different pollutants are essential to obtain important information on plasticizers' sublethal effects. This review analyses the current advances in the adverse effects of plasticizers (as emerging contaminants), such as immunological response disruption. The review also shows a critical analysis of the effects of the most widely used plasticizers on haemocytes. The advantages of an integrative approach that uses chemical, genetic, and immunomarker assays to monitor toxicity are highlighted. All these factors are imperative to ponder when designing toxicity studies to recognize the potential effects of plasticizers like bisphenol A and phthalates.

1,1,1-trichloro-2,2-bis (p-chlorophenyl)-ethane (DDT) and 1,1-Dichloro-2,2-bis (p, p'-chlorophenyl) ethylene (DDE) as endocrine disruptors in human and wildlife: A possible implication of mitochondria

1,1,1-trichloro-2,2-bis (p-chlorophenyl)-ethane (DDT) and its main metabolite 1,1-Dichloro-2,2-bis (p, p'-chlorophenyl) ethylene (DDE) act as endocrine disruptors in humans and wildlife. Immunomodulatory functions have also been attributed to both xenobiotics. DDT was banned in the 1970s due to its toxicity, but it is still produced and used for indoor residual spraying with disease vector control purposes. Due to their persistence and lipophilic properties, DDT and DDE can bioaccumulate through the food chain, being stored in organisms' adipose depots. Their endocrine disruptor function is mediated by agonist or antagonist interaction with nuclear receptors. Present review aimed to provide an overview of how DDT and DDE exposure impacts reproductive and immune systems with estrogen-disrupting action in humans and wildlife. Studies showing DDT and DDE impact on mitochondrial function and apoptosis pathway will also be reviewed, suggesting the hypothesis of direct action on mitochondrial steroid receptors.

Assessment of the effect of long-term exposure to microplastics and depuration period in Sparus aurata Linnaeus, 1758: Liver and blood biomarkers

The constant increase in plastic pollution has attracted great attention in recent years due to its potential detrimental effects on organisms and ecosystems. While the consequences of ingestion of large plastic litter are mostly understood, the impacts resulting from a long-term exposure and a recovery period of microplastics (MPs) are still limited. The aims were to monitor oxidative stress, detoxification and inflammatory biomarkers in liver, plasma and erythrocytes of Sparus aurata exposed during 90 days to low-density polyethylene (LDPE)-MPs enriched diet (10% by weight) followed by 30 days of depuration. Exposure to LDPE-MPs progressively activates the antioxidant and detoxification system and induces an inflammatory response in liver and plasma, whereas no significant changes were observed in erythrocytes. The plasma activities of catalase, myeloperoxidase (MPO), lysozyme and the levels of malondialdehyde (MDA) as maker of lipid peroxidation significantly increased after exposure to LDPE-MPs for 90 days compared to the control group. The activities of all antioxidant enzymes - catalase, superoxide dismutase, glutathione peroxidase and glutathione reductase-, the detoxification enzyme glutathione s-transferase, MPO, the production of reactive oxygen species and the levels of MDA were also significantly increased in liver after MPs exposure. Additionally, all these biomarkers tended to recover during the depuration period, most of them reaching similar levels to those of the control group. In conclusion, the ingestion of a diet containing LDPE-MPs for 90 days induced a progressive increase in oxidative stress and inflammation biomarkers in liver and plasma of S. aurata but not in erythrocytes, which tended to regain control values when not exposed to MPs for 30 days. The present study contributes to a better understanding of the toxic effects of MPs in S. aurata and highlights the usefulness of plasma that can be obtained in a minimally invasive way to monitor these effects.

Acute hypoxic exposure: Effect on hemocyte functional parameters and antioxidant potential in gills of the pacific oyster, Crassostrea gigas

Bivalve mollusks are frequently subjected to fluctuations of dissolved oxygen concentration in the environment which can represent a significant threat to bivalve antioxidant status. In this work the effects of hypoxia on hemocyte reactive oxygen species (ROS) production and level of mitochondrial potential as well as the activity and expression level of catalase (CAT) and superoxide dismutase (SOD) in gills of Crassostrea gigas were investigated after 24 h and 72 h exposure. 24 h hypoxia promoted an increase of mitochondrial membrane potential in agranulocytes and induced ROS accumulation in granulocytes. 72 h exposure substantially decreased hemocyte mitochondrial potential and intracellular ROS level in all hemocyte types. No significant changes in the activity of CAT in gills were observed following both 24 h and 72 h exposure periods compared to control. SOD activity in gills decreased after 72 h exposure to hypoxia but did not change under 24 h hypoxia. Significant up-regulation of SOD gene and no changes in expression level of CAT were observed in all experimental groups. The results indicate an overall shift in antioxidant status in gills and hemocytes of the Pacific oyster that may act as compensatory mechanisms to maintain redox homeostasis after a short-term (24 h) exposure and represent the occurrence of oxidative stress conditions at the end of 72 h hypoxia.

Stress responses in expressions of microRNAs in mussel Mytilus galloprovincialis exposed to cadmium

MicroRNAs (miRNAs) are known to have complicated functions in aquatic species, but little is known about the role of miRNAs in mollusk species under environmental stress. In this study, we performed small RNA sequencing to characterize the differentially expressed miRNAs in different tissues (whole tissues, digestive glands, gills, and gonads) of blue mussels (Mytilus galloprovincialis) exposed to cadmium (Cd). In summary, 107 known miRNAs and 32 novel miRNAs were significantly (p < 0.01) differentially expressed after Cd exposure. The peak size of miRNAs was 22 nucleotides. Target genes of these differentially expressions of miRNAs related to immune defense, apoptosis, lipid and xenobiotic metabolism showed significant changes under Cd stress. These findings provide the first characterization of miRNAs in mussel M. galloprovincialis and expressions of many target genes in response to Cd stress.

Integrated analysis of miRNAome and transcriptome reveals miRNA-mRNA network regulation in Vibrio alginolyticus infected thick shell mussel Mytilus coruscus

The thick shell mussel Mytilus coruscus has developed into a model species for studying the interaction between molluscs and environmental stimuli. Herein, integrated analysis of miRNAome and transcriptome was performed to reveal miRNA-mRNA network regulation in Vibrio alginolyticus infected M. coruscus. There have detected some histological abnormalities in digestive gland and gills of V. alginolyticus challenged mussels, ascertaining the effective irritation by the present bacterial strain. A total of 265 novel miRNAs were finally predicted, of which 26 were differentially expressed miRNAs (DEMs). Additionally, 667 differentially expressed genes (DEGs) were detected, which may be potentially associated with innate immune response to V. alginolyticus infection. A regulatory network linked to 22 important pathways and 16 DEMs and 34 OGs was constructed. Some traditional immune-related signaling pathways such as toll-like receptor signaling pathway (TLR) signaling pathway, transforming growth factor-beta (TGF-beta) signaling pathway, peroxisome, phagosome, lysosome, mammalian target of rapamyoin (mTOR) signaling pathway were linked to specific miRNAs and genes in this network. Further, interactional relationship between certain miRNAs and TLR pathway was dissected, which the results predicted that a number of TLRs and TLR-associated signaling genes including TLR1, TLR2, TLR4, TLR6, IRAK1, TRAF6, MAPK, and IL-17 were negatively regulated by novel_miR_11, novel_miR_145, novel_miR_196, novel_miR_5, novel_miR_163 and novel_miR_217 in the TLR pathway. Additionally, interactional relationship between novel_miR_145 and TLR2 was validated by laboratory experiment. The integrated analysis of mRNA and microRNA deep sequencing data exhibited a sophisticated miRNA-mRNA regulation network in M. coruscus in response to V. alginolyticus challenge, which shed a new light on the underlying mechanism of molluscan confronting bacterial infection.

MicroRNA-mediated stress response in bivalve species

Bivalve mollusks are important aquatic organisms, which are used for biological monitoring because of their abundance, ubiquitous nature, and abilities to adapt to different environments. MicroRNAs (miRNAs) are small noncoding RNAs, which typically silence the expression of target genes; however, certain miRNAs directly or indirectly upregulate their target genes. They are rapidly modulated and play an essential role in shaping the response of organisms to stresses. Based on the regulatory function and rapid alteration of miRNAs, they could act as biomarkers for biotic and abiotic stress, including environmental stresses and contaminations. Moreover, mollusk, particularly hemocytes, rapidly respond to environmental changes, such as pollution, salinity changes, and desiccation, which makes them an attractive model for this purpose. Thus, bivalve mollusks could be considered a good animal model to examine a system's response to different environmental conditions and stressors. miRNAs have been reported to adjust the adaptation and physiological functions of bivalves during endogenous and environmental stressors. In this review, we aimed to discuss the potential mechanisms underlying the response of bivalves to stressors and how miRNAs orchestrate this process; however, if necessary, other organisms' response is included to explain specific processes.

microRNAs Mediated Regulation of the Ribosomal Proteins and its Consequences on the Global Translation of Proteins

Ribosomal proteins (RPs) are mostly derived from the energy-consuming enzyme families such as ATP-dependent RNA helicases, AAA-ATPases, GTPases and kinases, and are important structural components of the ribosome, which is a supramolecular ribonucleoprotein complex, composed of Ribosomal RNA (rRNA) and RPs, coordinates the translation and synthesis of proteins with the help of transfer RNA (tRNA) and other factors. Not all RPs are indispensable; in other words, the ribosome could be functional and could continue the translation of proteins instead of lacking in some of the RPs. However, the lack of many RPs could result in severe defects in the biogenesis of ribosomes, which could directly influence the overall translation processes and global expression of the proteins leading to the emergence of different diseases including cancer. While microRNAs (miRNAs) are small non-coding RNAs and one of the potent regulators of the post-transcriptional gene expression, miRNAs regulate gene expression by targeting the 3' untranslated region and/or coding region of the messenger RNAs (mRNAs), and by interacting with the 5' untranslated region, and eventually finetune the expression of approximately one-third of all mammalian genes. Herein, we highlighted the significance of miRNAs mediated regulation of RPs coding mRNAs in the global protein translation.

Discovery and functional understanding of MiRNAs in molluscs: a genome-wide profiling approach

Small non-coding RNAs play a pivotal role in gene regulation, repression of transposable element and viral activity in various organisms. Among the various categories of these small non-coding RNAs, microRNAs (miRNAs) guide post-translational gene regulation in cellular development, proliferation, apoptosis, oncogenesis, and differentiation. Here, we performed a genome-wide computational prediction of miRNAs to improve the understanding of miRNA observation and function in molluscs. As an initial step, hundreds of conserved miRNAs were predicted in 35 species of molluscs through genome scanning. Afterwards, the miRNAs' population, isoforms, organization, and function were characterized in detail. Furthermore, the key miRNA biogenesis factors, including AGO2, DGCR8, DICER, DROSHA, TRABP2, RAN, and XPO5, were elucidated based on homologue sequence searching. We also summarized the miRNAs' function in biomineralization, immune and stress response, as well as growth and development in molluscs. Because miRNAs play a vital role in various lifeforms, this study will provide insight into miRNA biogenesis and function in molluscs, as well as other invertebrates.

Stimulation of Mytilus galloprovincialis Hemocytes With Different Immune Challenges Induces Differential Transcriptomic, miRNomic, and Functional Responses

Mediterranean mussels (Mytilus galloprovincialis) are marine bivalve molluscs with high resilience to biotic and abiotic stress. This resilience is one of the reasons why this species is such an interesting model for studying processes such as the immune response. In this work, we stimulated mussel hemocytes with poly I:C, β-glucans, and LPS and then sequenced hemocyte mRNAs (transcriptome) and microRNAs (miRNome) to investigate the molecular basis of the innate immune responses against these pathogen-associated molecular patterns (PAMPs). An immune transcriptome comprising 219,765 transcripts and an overview of the mussel miRNome based on 5,175,567 non-redundant miRNA reads were obtained. The expression analyses showed opposite results in the transcriptome and miRNome; LPS was the stimulus that triggered the highest transcriptomic response, with 648 differentially expressed genes (DEGs), while poly I:C was the stimulus that triggered the highest miRNA response, with 240 DE miRNAs. Our results reveal a powerful immune response to LPS as well as activation of certain immunometabolism- and ageing/senescence-related processes in response to all the immune challenges. Poly I:C exhibited powerful stimulating properties in mussels, since it triggered the highest miRNomic response and modulated important genes related to energy demand; these effects could be related to the stronger activation of these hemocytes (increased phagocytosis, increased NO synthesis, and increased velocity and accumulated distance). The transcriptome results suggest that after LPS stimulation, pathogen recognition, homeostasis and cell survival processes were activated, and phagocytosis was induced by LPS. β-glucans elicited a response related to cholesterol metabolism, which is important during the immune response, and it was the only stimulus that induced the synthesis of ROS. These results suggest a specific and distinct response of hemocytes to each stimulus from a transcriptomic, miRNomic, and functional point of view.

Long-term exposure to microplastics induces oxidative stress and a pro-inflammatory response in the gut of Sparus aurata Linnaeus, 1758

Environmental pollution from plastic debris is a major global concern, being a potential threat to marine organisms and ecosystems. The accumulation of microplastics (MPs) in the oceans has notable ecological implications due to their long persistence, their potential ecotoxicity, and their ability to adsorb other pollutants and act as vectors of pathogens. Nevertheless, whereas the number of investigations documenting the presence of MPs in wild fish has increased, less studies have addressed the toxicological effects associated with the ingestion of MPs in long-term laboratory conditions. The aim of the present study was to assess the physiological response of gilthead seabream (Sparus aurata) exposed to low-density polyethylene (LDPE) MPs during a 90-day exposure followed by an extra 30 days of depuration through the application of oxidative stress biomarkers in the gut. No changes were observed in the Fulton condition factor of fish associated with MP intake. The activities of antioxidant enzymes and glutathione s-transferase and the levels of reduced glutathione progressively increased throughout the study in the MPs-fed group compared to the control group, reaching the highest values at 90 days. Similarly, the activity of the pro-inflammatory enzyme, myeloperoxidase, and the levels of oxidative damage markers -malondialdehyde and protein carbonyls-also increased after 90 days of exposure to an enriched diet with MPs. During the 30-day depuration period, all the biomarkers analysed tended to normalize, with the majority recovering values similar to those of the control group. In conclusion, MPs exposure during 90 days to S. aurata induced oxidative stress and a pro-inflammatory response in gut, and were able to recover after the exposure to MPs was removed.

Acute effects of neonicotinoid insecticides on Mytilus galloprovincialis: A case study with the active compound thiacloprid and the commercial formulation calypso 480 SC

Pesticides can enter aquatic environments potentially affecting non-target organisms. Unfortunately, the effects of such substances are still poorly understood. This study investigated the effects of the active neonicotinoid substance thiacloprid (TH) and the commercial product Calypso 480 SC (CA) (active compound 40.4% TH) on Mytilus galloprovincialis after short-term exposure to sublethal concentrations. Mussels were tested for seven days to 0, 1, 5 and 10 mg L^-1 TH and 0, 10, 50 and 100 mg L^-1 CA. For this purpose, several parameters, such as cell viability of haemocytes and digestive cells, biochemical haemolymph features, superoxide dismutase (SOD) and catalase (CAT) enzymatic activity of gills and digestive gland, as well as histology of such tissues were analysed. The sublethal concentrations of both substances lead to abatement or completely stopping the byssal fibres creation. Biochemical analysis of haemolymph showed significant changes (P < 0.01) in electrolytes ions (Cl^-, K⁺, Na⁺, Ca²⁺, S-phosphor), lactate dehydrogenase (LDH) enzyme activity and glucose concentration following exposure to both substances. The TH-exposed mussels showed significant imbalance (P < 0.05) in CAT activity in digestive gland and gills. CA caused significant decrease (P < 0.05) in SOD activity in gills and in CAT activity in both tissues. Results of histological analyses showed severe damage in both digestive gland and gills in a time- and concentration-dependent manner. This study provides useful information about the acute toxicity of a neonicotinoid compound and a commercial insecticide on mussels. Nevertheless, considering that neonicotinoids are still widely used and that mussels are very important species for marine environment and human consumption, further researches are needed to better comprehend the potential risk posed by such compounds to aquatic non-target species.

Immunotoxicity of petroleum hydrocarbons and microplastics alone or in combination to a bivalve species: Synergic impacts and potential toxication mechanisms

Both the frequent occurrence of accidental petroleum spills and the ubiquitous presence of microplastics (MPs) in the sea may pose severe threats to marine species. However, the immunotoxic impacts of these two types of pollutants and the underlying toxication mechanisms still remain largely unknown in sessile filter-feeding bivalve mollusks. Therefore, the impacts of exposure to petroleum hydrocarbons and MPs alone or in combination on the total count, cell type composition, and phagocytic activity of hemocytes were investigated in the blood clam, Tegillarca granosa. In addition, the intracellular ROS content, cell viability, degree of DNA damage, and expression levels of genes from immune-, apoptosis-, and immunotoxicity-related pathways were analyzed to reveal the potential toxication mechanisms. The results demonstrated that exposure to petroleum hydrocarbons and MPs alone or in combination at environmentally realistic concentrations could exert significant immunotoxic impacts on the blood clam, which may be caused by alterations in a series of physiological and molecular processes. In addition, the immunotoxicity of petroleum hydrocarbons could be significantly aggravated by the copresence of MPs, which suggests that coexposure to these two pollutants deserves closer attention.

A species-specific miRNA participates in biomineralization by targeting CDS regions of Prisilkin-39 and ACCBP in Pinctada fucata

Biomineralization is a sophisticated biological process precisely regulated by multiple molecules and pathways. Accumulating miRNAs have been identified in invertebrates but their functions in biomineralization are poorly studied. Here, an oyster species-specific miRNA, novel_miR_1 was found to regulate biomineralization in Pinctada fucata. Target prediction showed that novel_miR_1 could target Prisilkin-39 and ACCBP by binding to their coding sequences (CDS). Tissue distribution analysis revealed that the expression level of novel_miR_1 was highest in the mantle, which was a key tissue participating in biomineralization. Gain-of-function assay in vivo showed that biomineralization-related genes including Prisilkin-39 and ACCBP were down-regulated and shell inner surfaces of both prismatic and nacreous layer were disrupted after the over-expression of novel_miR_1, indicating its dual roles in biomineralization. Furthermore, the shell notching results indicated that novel_miR_1 was involved in shell regeneration. Dual-luciferase reporter assay in vitro demonstrated that novel_miR_1 directly suppressed Prisilkin-39 and ACCBP genes by binding to the CDS regions. Taken together, these results suggest that novel_miR_1 is a direct negative regulator to Prisilkin-39 and ACCBP and plays an indispensable and important role in biomineralization in both prismatic and nacreous layer of P. fucata.

Profiling of microRNAs and mRNAs in marine mussel Mytilus galloprovincialis

MicroRNAs (miRNAs) are a class of noncoding RNA molecules containing 18-24 nucleotides, and those with conserved structures are able to regulate the expression of eukaryotic genes by inhibition or enhancement of mRNA translation. However, miRNAs of the blue mussel, Mytilus galloprovincialis have not been reported. M. galloprovincialis is a primary species distributed along coastal zones worldwide. To reveal the repertoire of miRNAs in M. galloprovincialis, we constructed small RNA libraries prepared from three different mussels, which were then sequenced by Solexa deep sequencing technology. A total of 32,836,817, 33,359,113 and 33,093,562 clean reads from the tissues of the three M. galloprovincialis were obtained. Based on sequence similarities and hairpin structure predictions, 137 M. galloprovincialis miRNAs (mg-miRNA) were identified. Among the mg-miRNAs, 104 were conserved across species, whereas 33 might be novel and specific for M. galloprovincialis. Some of the mg-miRNAs, such as let-7 and the miR-100 family are playing key roles in many metabolic pathways and are worthy of further study. By performing a whole genome-scale characterization of mg-miRNAs and proposing their potential functions, these results provide a foundation for understanding the biological processes of the blue mussel, M. galloprovincialis.

The effect of foodborne sertraline on rainbow trout (Oncorhynchus mykiss)

The worldwide consumption of antidepressants is raising as well as their concentrations in the aquatic environment. This increases the risk of food chain contamination and bioaccumulation in aquatic biota. The aim of this study was to describe a potential risk of sertraline as a pollutant from water environment, wherein rainbow trout (Oncorhynchus mykiss) has been chosen as the test organism, because predatory fish are on the top of the food chain in the aquatic environment. The effects of foodborne sertraline were tested on rainbow trout during a 28-day toxicity test according to OECD 215 method. Sertraline was incorporated in commercial feed at a dose of 4.4 µg/kg (environmental concentration), 42 µg/kg and 400 µg/kg. The results confirmed that sertraline has a significant effect on fish behaviour, resulting in suppression of the escape reflex and increased resistance to stress. Moreover, increased Fultońs condition factor was found in fish fed with the highest concentration of sertraline. Haematological analysis revealed a statistically significant increase in the number of neutrophilic bands and neutrophil/lymphocyte ratio, and decreased number of lymphocytes. The results of biochemical examination showed a statistically significant decrease in ammonia and lactate concentrations and histological examination revealed changes in gills and caudal kidney. Although sertraline reduces stress in fish, the decline in nonspecific immunity is a risk to fish population stability.

Application of the microRNA-302/367 cluster in cancer therapy

As a novel class of noncoding RNAs, microRNAs (miRNAs) can effectively silence their target genes at the posttranscriptional level. Various biological processes, such as cell proliferation, differentiation, and motility, are regulated by miRNAs. In different diseases and different stages of disease, miRNAs have various expression patterns, which makes them candidate prognostic markers and therapeutic targets. Abnormal miRNA expression has been detected in numerous neoplastic diseases in humans, which indicates the potential role of miRNAs in tumorigenesis. Previous studies have indicated that miRNAs are involved in nearly the entire process of tumor development. MicroRNA‐302a, miR‐302b, miR‐302c, miR‐302d, and miR‐367 are members of the miR‐302/367 cluster that plays various biological roles in diverse neoplastic diseases by targeting different genes. These miRNAs have been implicated in several unique characteristics of cancer, including the evasion of growth suppressors, the sustained activation of proliferative signaling, the evasion of cell death and senescence, and the regulation of angiogenesis, invasion, and metastasis. This review provides a critical overview of miR‐302/367 cluster dysregulation and the subsequent effects in cancer and highlights the vast potential of members of this cluster as therapeutic targets and novel biomarkers.

Genomics and immunity of the Mediterranean mussel Mytilus galloprovincialis in a changing environment

The Mediterranean mussel (Mytilus galloprovincialis) is a marine invasive species cultured all over the world. Mussels are an appreciated resource in local aquaculture enterprises because of their robust production and resilience that translates into a reliable economic value. So far, no massive mortalities have been reported in natural or cultured populations of this species. In the last years, the knowledge about its immune system has greatly improved but there are still many questions to be answered. One of them is why mussels, with their high filtering activity, are able to be exposed to a high number of potential pathogens without getting infected and without developing an elevated inflammatory response. The sequencing of the mussel genome has revealed a very complex organization with high heterozygosity, abundance of repetitive sequences and extreme intraspecific sequence diversity among individuals, mainly in immune related genes. Among those genes, antimicrobial peptides are the most expressed gene families in mussels, highly polymorphic and with antimicrobial effect against molluscs pathogens, but also against pathogens of lower vertebrates and humans. The combination of a complex genome with the adaptation of mussel immune system to a changing environment could explain this high variability, not only in immune-related genes, but also in the functional response among individuals sampled in the same location and date.

Azinphos-methyl causes in Planorbarius corneus toxic effects on reproduction, offspring survival and B-esterases depending on the exposure time

This work aimed to study in the freshwater gastropod Planorbarius corneus the effects of acute (2 days) and subchronic (14 days) exposures to an environmental concentration of the organophosphate azinphos-methyl on different reproductive parameters, offspring survival and B-esterase activities in gonads and in the whole organism soft tissue. The acute exposure inhibited only carboxylesterase activity in both tissues while the subchronic exposure also inhibited cholinesterase activity, decreased the number of hatched-eggs and increased offspring lethality (92%). On the other hand, B-esterases in gonads were more effective biomarkers than B-esterases in the whole organism due their inhibition appeared earlier in time (cholinesterase activity) and their activity remained inhibited for a longer time (carboxylesterase activity) when recovery studies were performed. We concluded that B-esterases and reproductive parameters can be used as effect biomarkers of aquatic contamination with azinphos-methyl. Our studies showed that a 14 days exposure to an environmental concentration of azinphos-methyl produced severe signs of toxicity in adult organisms, egg masses and juveniles that could cause negative effects at the population level in contaminated environments.

mRNA expression of antioxidant and biotransformation enzymes in zebrafish (Danio rerio) embryos after exposure to the tricyclic antidepressant amitriptyline

Now-a-days, the occurrence of antidepressant residues in surface waters has become a major concern. Amitriptyline (AMI) has been described to treat depression and other disorders for decades. However, little is known about its effect on non-target organisms. The aim of this study was to assess the potential impact of AMI on the mRNA expression of antioxidant and detoxification enzymes during the early embryonic development of zebrafish (Danio rerio). Fertilized D. rerio embryos were exposed to AMI at concentrations of 300 ng/L and 30 μg/L and sampled 24, 48, 96, and 144 h post fertilization (hpf) to assess the mRNA expressions of cytochrome P450 1A1, glutathione-S-transferase, glutathione peroxidase, superoxide dismutase, and catalase. The time courses of the mRNA expressions of antioxidant and detoxification enzymes revealed characteristic changes during embryonic development causing generally transient changes post hatching; however, AMI did not cause any significant impact except in the case of CAT after 144 h, which was significantly upregulated by the AMI concentration of 30 μg/L. The results suggest that the antidepressant AMI causes only moderate to minor impacts on antioxidant and detoxification enzymes during early embryonic development of the non-target organism D. rerio and that CAT is the only biomarker affected by AMI.

Effects of dietary fluoranthene on nymphs of Blaptica dubia S. (Blattodea: Blaberidae)

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants which exert detrimental effects on living beings. Considering the health risk associated with exposure to these pollutants, their presence in food increases efforts to establish early-warning indicators of pollution. We aimed to examine the effects of environmentally relevant concentrations of fluoranthene (0.2 ng and 18 ng/g dry weight of diet) on the activities of midgut antioxidant and detoxification enzymes in Blaptica dubia. Significant changes of superoxide dismutase and catalase activities, recorded at the higher fluoranthene concentration regardless of the exposure time, suggest that they may be used as biomarkers of PAH pollution. Increased GST activity and decreased total GSH content, detected upon acute exposure to the lower concentration, indicate processes of detoxification. Reorganization of B. dubia mechanisms of defense in response to oxidative stress caused by exposure to dietary PAH point to the necessity for further examination of fluoranthene actions.

Involvement of inducible nitric oxide synthase (iNOS) in immune-functioning of Paphia malabarica (Chemnitz, 1782)

In recent years, the role of inducible nitric oxide synthase (iNOS) isoform has been widely studied because of its immunological relevance in higher organisms as well as invertebrates including bivalves. However, little is known about the immunological role of iNOS in Paphia malabarica defense mechanism. In this study, we immunodetected the presence of iNOS in P. malabarica hemocytes using antibody N9657 monoclonal anti-nitric oxide synthase. In addition, increased iNOS activity was evident in response to a higher bacterial dosage (Vibrio parahaemolyticus and V. cholerae), highlighting the dose-dependent iNOS activity induction. Also, higher bacterial survivability was observed in the presence of iNOS inhibitor, i.e., S-methylisothiourea hemisulphate (SMIS) thus, validating the bactericidal role of iNOS. These findings implicate the involvement of iNOS in immune-functioning of P. malabarica. Future work should focus on elucidating the expression and regulation of pathogenesis in P. malabarica, involving iNOS.

Modulation of mitochondrial functions by xenobiotic-induced microRNA: From environmental sentinel organisms to mammals

Mitochondria play a crucial role in energetic metabolism, signaling pathways, and overall cell viability. They are in the first line in facing cellular energy requirements in stress conditions, such as in response to xenobiotic exposure. Recently, a novel regulatory key role of microRNAs (miRNAs) in important signaling pathways in mitochondria has been proposed. Consequently, alteration in miRNAs expression by xenobiotics could outcome into mitochondrial dysfunction, reactive oxygen species overexpression, and liberation of apoptosis or necrosis activating proteins. The aim of this review is to show the highlights about mitochondria-associated miRNAs in cellular processes exposed to xenobiotic stress in different cell types involved in detoxification processes or sensitive to environmental hazards in marine sentinel organisms and mammals.

β-1, 3 glucan binding protein based selenium nanowire enhances the immune status of Cyprinus carpio and protection against Aeromonas hydrophila infection

In the present study, immunoenhancing effect of β-1, 3 glucan binding protein based selenium nanowire (Phβ-GBP-SeNWs) in common carp, Cyprinus carpio was assessed. Biological based selenium nanoform was synthesized, using crustacean immune molecule β-GBP purified from the haemolymph of Paratelphusa hydrodromus. The morphological property of Phβ-GBP-SeNWs was analyzed through TEM which reveals, the synthesized nanowire exhibits approximately 30-50 nm width with smooth surface. For this current study, fish were fed with experimental diet includes Phβ-GBP, sodium selenite, selenomethionine and Phβ-GBP-SeNWs supplemented diet at different concentrations (0.5 mg, 1 mg and 2 mg) for 30 days. The growth performance, cellular and humoral immune responses (myeloperoxidase, reactive oxygen species, alkaline phosphatase and lysozyme activity) and antioxidant enzymes (glutathione peroxidase and catalase activity) in the fish fed with Phβ-GBP-SeNWs supplemented diet were significantly increased in dose-dependent manner, which was observed at two different interval period (15^th and 30^th day). Also, Phβ-GBP-SeNWs supplemented diet fed fish gain resistant after challenged with aquatic pathogen Aeromonas hydrophila and the relative survival percentage was increased. Agar disc diffusion and BacLight assay clearly demonstrated the antibacterial property of plasma of fish fed with Phβ-GBP-SeNWs supplemented diet against aquatic pathogen A. hydrophila, Vibrio parahaemolyticus and Vibrio alginolyticus. Moreover, confocal laser scanning microscopic analysis clearly showed that, Phβ-GBP-SeNWs supplemented diet fed fish plasma was more efficient in disrupting the architecture of bacterial colonies and thereby reduced the thickness of biofilm. Thus, the present study indicates that, incorporation of Phβ-GBP-SeNWs in the diet enhances the fish immune responses and disease resistance against aquatic pathogens.

The use of carboxylesterases as biomarkers of pesticide exposure in bivalves: A methodological approach

Bivalves are worldwide sentinels of anthropogenic pollution. The inclusion of biomarker responses in chemical monitoring is a recommended practise that has to overcome some difficulties. One of them is the time frame between sample collection and sample processing in order to ensure the preservation of enzymatic activities. In the present study, three bivalve species of commercial interest (mussel, Mytilus galloprovincialis, razor shell, Solen marginatus, and cockle, Cerastoderma edule) were processed within <2 h after being retrieved from their natural habitat, and 24 h after being transported in air under cold conditions (6-8 °C) to laboratory facilities. The enzymatic activities were compared in the three species submitted to both conditions revealing no differences in terms of carboxylesterase dependent activities (CEs) using different substrates: p-nitrophenyl acetate (pNPA), p-nitrophenyl butyrate (pNPB), 1-naphthyl acetate (1-NA), 1-naphthyl butyrate (1-NB) and 2-naphthyl acetate (2-NA). In mussels, three tissues were selected (haemolymph, gills and digestive gland). For comparative purposes, in razor shell and cockle only digestive gland was considered as it is the main metabolic organ. Baseline enzymatic activities for CEs were characterised in the digestive gland of the three bivalves using four out of the five selected CE substrates as well as the kinetic parameters (V_max and K_m) and catalytic efficiency. The in vitro sensitivity to the organophosphorus metabolite chlorpyrifos oxon was also calculated. IC₅₀ values (pM-nM range) were lower than those obtained for vertebrate groups which suggest that bivalves have high protection efficiency against this pesticide as well as species dependent particularities.

MiR-205 Mediated Cu-Induced Lipid Accumulation in Yellow Catfish Pelteobagrus fulvidraco

The present working hypothesis is that the Cu-induced changes in lipid metabolism may be mediated by miRNAs. Here, we describe the miRNA profile of the liver tissues of yellow catfish exposed to waterborne Cu, based on larger-scale sequencing of small RNA libraries. We identified a total of 172 distinct miRNAs. Among these miRNAs, compared to the control, mRNA expression levels of 16 miRNAs (miR-203a, 205, 1788-3p, 375, 31, 196a, 203b-3p, 2187-5p, 196d, 459-3p, 153a and miR-725, and two novel-miRNAs: chr4-1432, chr-7684) were down-regulated, and mRNA levels of miR-212 and chr20-5274 were up-regulated in Cu-exposed group. The functions of their target genes mainly involved ether lipid metabolism, glycerophospholipid metabolism, linoleic acid metabolism and α-linolenic acid metabolism. Cu exposure inhibited the expression of miR-205, whose predicted target genes were enriched in the pathway of lipid metabolism, including fas, lxrα, ddit3, lamp2, casp3a and baxa. These potential target genes were further verified by Dual-luciferase reporter gene assay. Using primary hepatocytes of yellow catfish, Cu incubation down-regulated miR-205 expression, and increased TG contents and FAS activity. LXR antagonist effectively ameliorate the Cu-induced change of TG content and FAS activity. These data suggest that down-regulation of the miRNA-205 may be an important step in Cu-induced changes in lipid metabolism in yellow catfish.

Mussel digestive gland as a model tissue for assessing xenobiotics: An overview

Control strategies and routine biomonitoring programs are commonly performed worldwide using sentinel marine invertebrates, such as mussels of the genus Mytilus, for assessing the "health status" of the aquatic environment. Those species can accumulate and tolerate xenobiotics at levels higher than those being present into the aquatic environment, thus providing accurate and reliable biological endpoints (e.g. physiological, behavioral, cellular, biochemical and molecular indices) that can be measured in their tissues. Taking under consideration the significance of bivalves for assessing the environmental hazard of xenobiotics being present into the water medium, as well as the key role of digestive gland as a target-tissue for the compounds ingested in the organism, the present study aimed to summarize available data on the effects of different categories of xenobiotic compounds, previously characterized as a potential threat for the marine ecosystems. In this context, different types of pharmaceuticals and personal care products (PPCPs), biocides, microplastics (MPs) and nanoparticles (NPs), currently investigated in mussels' digestive gland, using a battery of experimental approaches and analytical methods, as well as stress indices evaluation, are briefly described and further discussed in order to elucidate not only the presence and the toxic mode of action of xenobiotics, but also the important role of the digestive gland as a reliable target-tissue for investigating the effects of xenobiotics at cellular, biochemical, and molecular levels.

Identification and functional characterization of NEMO in Crassostrea gigas reveals its crucial role in the NF-κB activation

NEMO (NF-κB essential modulator) is one of the important regulatory subunits of the IκB kinase (IκK) complex that controls the activation of the NF-κB signaling pathway. Here, we have identified the homolog of NEMO from the pacific oyster Crassostrea gigas. CgNEMO harbors the conserved the IκK binding region, NEMO ubiquitin binding domain and Zinc finger domain. In terms of tissue distribution, CgNEMO is expressed in various tissues with an observed highest expression in the hemocytes. Furthermore, infection by two related Vibrio strains significantly increased CgNEMO expression in the hemocytes. Cell culture based luciferase reporter assays showed that CgNEMO activates the NF-κB reporter in a dose-pendent manner. Moreover, CgNEMO was also found to counter the IkB-dependent inhibitory effect on NF-κB activation, providing a plausible mechanism of NF-κB activation by CgNEMO. Meanwhile, site-directed mutagenesis demonstrated that the putative ubiquitination site K535 is required for the activation of NF-κB, implying that ubiquitination of NEMO may be involved in regulating its activity. Finally, RNAi mediated knockdown of CgNEMO in vivo significantly compromised the bacterial induction of key cytokines TNF-α and IL-17, strongly suggesting a role for CgNEMO in acute immune defense in oyster. In conclusion, this study provides new insights into our understanding about the evolution of NEMO mediated NF-κB activation and the induction of cytokine. Our findings may provide valuable information about diseases control and management in oyster aquaculture.

Effects of azinphos-methyl on enzymatic activity and cellular immune response in the hemolymph of the freshwater snail Chilina gibbosa

The use of a battery of biomarkers, especially those more closely related to species integrity, is desired for more complete ecotoxicological assessments of the effects of pesticide contamination on aquatic organisms. The phosphorodithioate azinphos-methyl has been intensively used in agriculture worldwide and have been found in the habitat of Chilina gibbosa, a freshwater snail endemic to South America. This snail has been proposed as a good model organism for ecotoxicity bioassays on the basis of studies focused mainly on enzymatic responses in whole tissue homogenates. Our aim was to evaluate the effect of an acute 48 h exposure to an environmental concentration of azinphos-methyl on C. gibbosa hemolymph enzymatic activity and cellular immune response. Our results show that cholinesterase activity was strongly inhibited (94%) in hemolymph of exposed snails. Carboxylesterase activity measured with p-nitrophenyl butyrate and glutathione S-transferase activity were augmented 47% and 89% respectively after exposure. No differences were found for hemolymph carboxylesterase activity measured with p-nitrophenyl acetate. These results differ from those reported for whole tissue homogenates and reveal that tissue-specific responses of enzymatic biomarkers exist in this species. Regarding immune cell response, hemocytes were identified for the first time for C. gibbosa. Their viability and phagocytic activity decreased after azinphos-methyl exposure although total number of circulating cells did not differ between treatments. We conclude that concentrations of azinphos-methyl that can be found in the environment can compromise both hemolymph cholinesterase activity and the immune system of C. gibbosa. Furthermore, we propose that carboxylesterase and glutathione S-transferase activities measured in hemolymph and hemocyte viability and phagocytic activity could be incorporated as sensitive biomarkers to evaluate the effects of pesticide exposure on this and related species.

Effects of waterborne antidepressants on non-target animals living in the aquatic environment: A review

After application, antidepressants, like other pharmaceuticals, are excreted from human body in their native form or as metabolites and enter the aquatic environment via different pathways. As concentrations of antidepressant residues in water continue to increase, their effects on non-target animals are being discussed. The aim of this study is to summarize current knowledge about the effects of wateborne antidepressants on non-target animals living in surface waters - invertebrates, fish and amphibians. Selective serotonin reuptake inhibitors such as fluoxetine, sertraline, and citalopram have been found to effect behavior, reproduction, and development in both invertebrates and vertebrates. Venlafaxine, belonging to the group of selective serotonin-noradrenalin reuptake inhibitors, not only affected behavior but also showed the potential to reduce survival in fish. Tricylic antidepressants are known to have various side-effects when consumed by humans. Moreover, in fish, exposure resulted in a significant increase in mortality, developmental retardation, morphological anomalies, and pathological changes in brain, heart, and cranial and caudal kidney. In addition, changes in antioxidant enzyme activity as well as increased lipid peroxidation were observed, even at the lowest tested concentrations. According to current knowledge, antidepressants occuring in surface water are able to affect the behavior, reproduction, development, and survival of aquatic invertebrates and vertebrates.

Alterations in haemolymph proteome of Mytilus galloprovincialis mussel after an induced injury

A proteomic and biochemical approach was performed to assess the effects of an induced muscle injury on the haemolymph of bivalve molluscs. For this purpose, Mytilus galloprovincialis were exposed to puncture of adductor muscle for three consecutive days, and their haemolymph proteome was then compared to healthy animals using 2-dimensional electrophoresis (2-DE) to identify proteins that differed significantly in abundance. Those proteins were then subjected to tandem mass spectrometry and 6 proteins, namely myosin, tropomyosin, CuZn superoxide dismutase (SOD), triosephosphate isomerase, EP protein and small heat shock protein were identified. SOD and tropomyosin changes were verified by spectrophotometric measurements and western blotting, respectively. As some of the proteins identified are related to muscular damage and oxidative stress, other biomarkers associated with these processes that can be evaluated by automatic biochemical assays were measured including troponin, creatine kinase (CK), and aspartate aminotransferase (AST) for muscle damage, and SOD, trolox equivalent antioxidant capacity (TEAC) and esterase activity (EA) for oxidative stress. Significantly higher concentrations of troponin, CK, AST, and TEAC were observed in mussels after puncture, being also possible biomarkers of non-specific induced damage.