Enhancement of leukemia-like phenotypes in Drosophila mxc mutant larvae due to activation of the RAS-MAP kinase cascade possibly via down-regulation of DE-cadherin.

Loss of mxc gene function in mature hemocytes of Drosophila mxcmbn1 mutant results in malignant hyperplasia in larval hematopoietic tissues termed lymph glands (LGs) owing to over-proliferation of immature cells. This is a useful model for genetic analyses of leukemia progression. To identify other mutations that deteriorate the hyperplasia, we aimed to investigate whether hyper-activation of common signaling cascade enabled to enhance the phenotypes. Ectopic expression of the constitutively active forms of MAPK signaling factors in the mutant increased the hyperplasia and the number of circulating hemocytes, resulting in the production of LG fragments. The LG phenotype was related to the reduced DE-cadherin level in the mutants. Depletion of Drosophila MCRIP, involved in MAPK-induced silencing of cadherin gene expression, exhibited a similar enhancement of the mxcmbn1 phenotypes. Furthermore, expression of MMP1 proteinase that cleaves the extracellular matrix proteins increased in the mutant larvae harboring MAPK cascade activation. Depletion of Mmp1 and that of pnt (required for Mmp1 expression) suppressed the LG hyperplasia. Hence, we speculated that reduction in DE-cadherin level by either down-regulation of MCRIP or up-regulation of MMP1 was involved in the progression of the tumor phenotype. Our findings can contribute to understanding the mechanism underlying human leukemia progression.

HIF-1 is involved in the regulation of expression of metallothionein and apoptosis incidence in different oxygen conditions in the white shrimp Litopenaeus vannamei.

The white shrimp Litopenaeus vannamei is exposed to hypoxic conditions in natural habitats and in shrimp farms. Hypoxia can retard growth, development and affect survival in shrimp. The hypoxia-inducible factor 1 (HIF-1) regulates many genes involved in glucose metabolism, antioxidant proteins, including metallothionein (MT) and apoptosis. In previous studies we found that the L. vannamei MT gene expression changed during hypoxia, and MT silencing altered cell apoptosis; in this study we investigated whether the silencing of HIF-1 affected MT expression and apoptosis. Double-stranded RNA (dsRNA) was used to silence HIF-1α and HIF-1ß under normoxia, hypoxia, and hypoxia plus reoxygenation. Expression of HIF-1α, HIF-1ß and MT, and apoptosis in hemocytes or caspase-3 expression in gills, were measured at 0, 3, 24 and 48 h of hypoxia and hypoxia followed by 1 h of reoxygenation. The results showed that hemocytes HIF-1α expression was induced during hypoxia and reoxygenation at 3 h, while HIF-1ß decreased at 24 and 48 h. In normoxia, HIF-1 silencing in hemocytes increased apoptosis at 3 h and decreased at 48 h; while in gills, caspase-3 increased at 3, 24 and 48 h. In hypoxia, HIF-1 silencing decreased apoptosis in hemocytes at 3 h, but caspase-3 increased in gills. During reoxygenation, apoptosis in hemocytes and caspase-3 in gills increased. During normoxia in hemocytes, silencing of HIF-1 decreased MT expression, but in gills, MT increased. During hypoxia and reoxygenation, silencing induced MT in hemocytes and gills. These results indicate HIF-1 differential participation in MT expression regulation and apoptosis during different oxygen conditions.

Establishing typical values for hemocyte mortality in individual California mussels, Mytilus californianus.

Hemocytes are immune cells in the hemolymph of invertebrates that play multiple roles in response to stressors; hemocyte mortality can thus serve as an indicator of overall animal health. However, previous research has often analyzed hemolymph samples pooled from several individuals, which precludes tracking individual responses to stressors over time. The ability to track individuals is important, however, because large inter-individual variation in response to stressors can confound the interpretation of pooled samples. Here, we describe protocols for analysis of inter- and intra-individual variability in hemocyte mortality across repeated hemolymph samples of California mussels, Mytilus californianus, free from typical abiotic stressors. To assess individual variability in hemocyte mortality with serial sampling, we created four groups of 15 mussels each that were repeatedly sampled four times: at baseline (time zero) and three subsequent times separated by either 24, 48, 72, or 168 h. Hemocyte mortality was assessed by fluorescence-activated cell sorting (FACS) of cells stained with propidium iodide. Our study demonstrates that hemolymph can be repeatedly sampled from individual mussels without mortality; however, there is substantial inter- and intra-individual variability in hemocyte mortality through time that is partially dependent on the sampling interval. Across repeated samples, individual mussels' hemocyte mortality had, on average, a range of ~6% and a standard deviation of ~3%, which was minimized with sampling periods ≥72 h apart. Due to this intra-individual variability, obtaining ≥2 samples from a specimen will more accurately establish an individual's baseline. Pooled-sample means were similar to individual-sample means; however, pooled samples masked the individual variation in each group. Overall, these data lay the foundation for future work exploring individual mussels' temporal responses to various stressors on a cellular level.

WSV152 induces apoptosis and promotes viral replication in Litopenaeus vannamei.

Previous studies have indicated that white spot syndrome virus (WSSV) infection induces apoptosis in many shrimp organs. However, the mechanism by which WSSV causes host apoptosis remains largely unknown. In this study, we demonstrated the function of wsv152, the first mitochondrial protein identified as encoded by WSSV. Glutathione S-transferase pulldown and co-immunoprecipitation analysis revealed that wsv152 interacts with the shrimp mitochondrial protein cytochrome c oxidase 5a (COX5a), a subunit of the COX complex. We also found that wsv152 expression significantly increased the rate of apoptosis, suggesting a role of wsv152 in WSSV-induced apoptosis in shrimp. Knockdown of wsv152 in vivo led to downregulation of several apoptosis-related shrimp genes, including cytochrome c, apoptosis-inducing factor and caspase-3. Suppression of wsv152 also resulted in significant reductions in the number of WSSV genome copies in tissues and in the mortality of WSSV-infected shrimp. Together, these results suggest that wsv152 targets host COX5a and is associated with the expression profiles of apoptosis-related shrimp genes. Wsv152 is likely also involved in WSSV-induced apoptosis, thereby facilitating virus infection and playing a complex role in WSSV pathogenesis.

The role of Astakine in Scylla paramamosain against Vibrio alginolyticus and white spot syndrome virus infection.

Astakine is a crucial factor in the proliferation and differentiation of hematopoietic stem cells and is directly involved in hematopoiesis in crustaceans. To assess the role of Astakine in the innate immune system of Scylla paramamosain, the immune responses in healthy and Astakine-inhibited S. paramamosain were investigated in the present study. The RNA transcripts of Astakine were widely distributed in all examined tissues, with significantly higher levels of expression in hemocytes of both healthy and challenged S. paramamosain with Vibrio alginolyticus and WSSV. When Astakine was knocked down by RNA interference technology, immune-related genes, including Janus kinase, prophenoloxidase, hemocyanin, ß-actin, myosin II essential light chain-like protein, signal transducer and activator of transcription, Relish, and C-type-lectin, were significantly down-regulated in hemocytes. The levels of phenoloxidaseactivity (PO), total hemocyte counts (THC) and hemocyte proliferation decreased significantly in hemocytes of Astakine-dsRNA treated S. paramamosain. After being challenged with V. alginolyticus and WSSV, the THC decreased significantly and the levels of hemocyte apoptosis increased significantly in Astakine-dsRNA treated S. paramamosain in comparison with those in infected groups without Astakine-dsRNA treatment. After being challenged with WSSV, the WSSV copies were significantly lower in Astakine-dsRNA treated groups than those in the WSSV infection group, which suggested that knockdown of Astakine was not conductive to WSSV replication and this might be associated with the decreasing THC. The results of survival analysis showed that the survival rate of V. alginolyticus or WSSV infected S. paramamosain decreased significantly following Astakine knockdown. These results suggested that RNA interference of Astakine might weaken the resistance of S. paramamosain to V. alginolyticus or WSSV infection. The weaken resistivity after knockdown Astakine might be related to the changes of important immune-related gene expression, THC, PO activity, proliferation and apoptosis of hemocytes.

Molecular characterization of troponin T in Scylla paramamosain and its role in Vibrio alginolyticus and white spot syndrome virus (WSSV) infection.

This study investigated the function of Troponin T (TnT) in the mud crab, Scylla paramamosain. The 1952 bp cDNA sequence of TnT was cloned from S. paramamosain using rapid amplification of cDNA ends (RACE) PCR. The quantitative real-time PCR analysis showed that TnT was highly expressed in the muscle and heart of S. paramamosain. Challenging with white spot syndrome virus (WSSV) or Vibrio alginolyticus (VA), two common pathogens that infect mud crabs, enhanced the expression of TnT in S. paramamosain. Knockdown of TnT using TnT-dsRNA led to up-regulating the expression of immune-related genes, such as c-type-lectin, toll-like-receptor, crustin antimicrobial peptide and prophenoloxidase. The cumulative mortality of WSSV- and VA-infected crabs was significantly increased following TnT knockdown. After WSSV or VA infection, TnT knockdown caused a significant reduction in phenoloxidase (PO) activity, superoxide dismutase (SOD) activity and total hemocyte count (THC), indicating a regulatory role of TnT in the innate immune response of S. paramamosain to pathogens. Apoptosis of hemocytes was higher in crabs treated with TnT-dsRNA compared with control crabs treated with phosphate-buffered saline. Knockdown of TnT increased apoptosis of hemocytes following VA infection, but reduced hemocyte apoptosis following WSSV infection. In summary, TnT may enhance the immune response of S. paramamosain to WSSV infection by regulating apoptosis, THC, PO activity and SOD activity. And TnT may play a positive role in the immune response against VA infection by regulating apoptosis, THC, SOD activity and PO activity.

Litopenaeus vannamei sirtuin 6 homolog (LvSIRT6) is involved in immune response by modulating hemocytes ROS production and apoptosis.

The histone deacetylase, sirtuin 6 (SIRT6), plays an essential role in the regulation of oxidative stress, mitochondrial function and inflammation in mammals. However, the specific role of SIRT6 in invertebrate immunity has not been reported. Here, we characterized for the first time, a sirtuin 6 homolog in Litopenaeus vannamei (LvSIRT6), with full-length cDNA of 2919 bp and 1536 bp open reading frame (ORF) encoding a putative protein of 511 amino acids, which contains a typical SIR2 domain. Sequence and phylogenetic analysis revealed that LvSIRT6 shares a close evolutionary relationship with SIRT6 from invertebrates. Real-time quantitative PCR analysis of LvSIRT6 transcripts revealed that they were ubiquitously expressed in shrimp and induced in hepatopancreas and hemocytes upon challenge with Vibrio parahaemolyticus, Streptococcus iniae, lipopolysaccharide (LPS), and white spot syndrome virus (WSSV), suggesting the involvement of LvSIRT6 in shrimp immune response. Moreover, knockdown of LvSIRT6 decreased mitochondrial membrane potential and increased total ROS level in hemocytes, especially upon V. parahaemolyticus challenge. Depletion of LvSIRT6 also increased hemocytes apoptosis in terms of decreased expression of pro-survival LvBcl-2, but increased expression of pro-apoptotic LvBax and LvCytochrome C, coupled with high LvCaspase3/7 activity. Shrimp were rendered more susceptible to V. parahaemolyticus infection upon LvSIRT6 knockdown. Taken together, our present data suggest that LvSIRT6 plays an important role in shrimp immune response by modulating hemocytes ROS production and apoptosis during pathogen challenge.

dOCRL maintains immune cell quiescence by regulating endosomal traffic.

Lowe Syndrome is a developmental disorder characterized by eye, kidney, and neurological pathologies, and is caused by mutations in the phosphatidylinositol-5-phosphatase OCRL. OCRL plays diverse roles in endocytic and endolysosomal trafficking, cytokinesis, and ciliogenesis, but it is unclear which of these cellular functions underlie specific patient symptoms. Here, we show that mutation of Drosophila OCRL causes cell-autonomous activation of hemocytes, which are macrophage-like cells of the innate immune system. Among many cell biological defects that we identified in docrl mutant hemocytes, we pinpointed the cause of innate immune cell activation to reduced Rab11-dependent recycling traffic and concomitantly increased Rab7-dependent late endosome traffic. Loss of docrl amplifies multiple immune-relevant signals, including Toll, Jun kinase, and STAT, and leads to Rab11-sensitive mis-sorting and excessive secretion of the Toll ligand Spåtzle. Thus, docrl regulation of endosomal traffic maintains hemocytes in a poised, but quiescent state, suggesting mechanisms by which endosomal misregulation of signaling may contribute to symptoms of Lowe syndrome.

Immune response to abamectin-induced oxidative stress in Chinese mitten crab, Eriocheir sinensis.

It is known that abamectin (ABM) inflicts oxidative damage on aquatic animals; however, knowledge about the immune response under pesticide-induced oxidative stress is incomplete. In the present study, several cellular and humoral immune parameters, including total haemocyte counts (THC), lysosomal membrane stability (LMS), activities of acid phosphatase (ACP), alkaline phosphatase (AKP) and lysozyme (LZM) were investigated to reveal the effects of ABM exposure on the immune defence mechanisms of the important freshwater crab, Erocheir sinensis. According to the results, a significant increase of THC was found in low concentration groups (0.03 and 0.06 mg/L), while dramatic decreases occurred in high concentration groups (0.12 and 0.24 mg/L) after 96 h of exposure. We also detected significant increases of reactive oxygen species (ROS) in haemocytes at 0.12 and 0.24 mg/L, and there was a dose- and time-dependent decrease of lysosomal membrane stability. These results suggest that the excessive generation of ROS induced by ABM may be leading the massive collapse of lysosomal membrane, which in turn may be causing the sharp drop of haemocyte counts in E. sinensis. The increase of hydrolytic enzymes ACP and AKP at low concentrations and the decrease at high concentrations also indicate an immune response associated with haemocytes status under stress. However, activities of LZM decreased significantly. After injection of Aeromonas hydrophil, mortalities increased under exposure to ABM and were positively related to ABM concentration. These results confirm that ABM exposure has the ability to impair immune defence and result in the host's susceptibility to pathogens.

Histologic Findings in Captive American Horseshoe Crabs (Limulus polyphemus).

Histopathology of 61 captive American horseshoe crabs (HSCs; Limulus polyphemus) is reviewed. HSC organs evaluated histologically included body wall (chitin, epidermis, dermis, and skeletal muscle), hepatopancreas, gut, gonads, book gills, eyes, heart, brain, and coxal gland. In descending order, lesions were most frequently identified in compound eye, body wall, book gills, hepatopancreas, chitinous gut, nonchitinous gut, heart, and brain; lesions were not observed in coxal gland or gonads. Hemocytes (also called amoebocytes) surrounded infectious agents and occluded ulcers. Large hemocyte aggregates had a central eosinophilic coagulum (ie, hemocyte coagulum). Cutaneous ulceration (34/60 cases), branchitis (29/48 cases), and ophthalmitis (17/20 cases) were common lesions and consistently associated with fungi, which were invasive into subjacent tissues, and/or bacteria, which were usually superficial. Fungal culture was performed in 3 cases and isolated Fusarium spp., although fungal morphology varied and multiple fungal species may have been present. Presumptive green algae were associated with ulceration in 1 case with minimal to no inflammation. Presumptive cyanobacteria were identified within a biofilm overlying the gills in 4 of 48 cases and were not invasive. Multifocal, random hepatopancreatitis was identified in 16 of 57 cases, 10 of which were associated with bacteria. Metacercarial cysts were identified in 25 of 61 cases and associated with minimal to no inflammation. Depleted eosinophilic globules in hepatopancreatic interstitial cells were interpreted as decreased nutritional status in 12 of 57 cases.

Remote Control of Intestinal Stem Cell Activity by Haemocytes in Drosophila.

The JAK/STAT pathway is a key signaling pathway in the regulation of development and immunity in metazoans. In contrast to the multiple combinatorial JAK/STAT pathways in mammals, only one canonical JAK/STAT pathway exists in Drosophila. It is activated by three secreted proteins of the Unpaired family (Upd): Upd1, Upd2 and Upd3. Although many studies have established a link between JAK/STAT activation and tissue damage, the mode of activation and the precise function of this pathway in the Drosophila systemic immune response remain unclear. In this study, we used mutations in upd2 and upd3 to investigate the role of the JAK/STAT pathway in the systemic immune response. Our study shows that haemocytes express the three upd genes and that injury markedly induces the expression of upd3 by the JNK pathway in haemocytes, which in turn activates the JAK/STAT pathway in the fat body and the gut. Surprisingly, release of Upd3 from haemocytes upon injury can remotely stimulate stem cell proliferation and the expression of Drosomycin-like genes in the intestine. Our results also suggest that a certain level of intestinal epithelium renewal is required for optimal survival to septic injury. While haemocyte-derived Upd promotes intestinal stem cell activation and survival upon septic injury, haemocytes are dispensable for epithelium renewal upon oral bacterial infection. Our study also indicates that intestinal epithelium renewal is sensitive to insults from both the lumen and the haemocoel. It also reveals that release of Upds by haemocytes coordinates the wound-healing program in multiple tissues, including the gut, an organ whose integrity is critical to fly survival.

Human NUP98-HOXA9 promotes hyperplastic growth of hematopoietic tissues in Drosophila.

Acute myeloid leukemia (AML) is a complex malignancy with poor prognosis. Several genetic lesions can lead to the disease. One of these corresponds to the NUP98-HOXA9 (NA9) translocation that fuses sequences encoding the N-terminal part of NUP98 to those encoding the DNA-binding domain of HOXA9. Despite several studies, the mechanism underlying NA9 ability to induce leukemia is still unclear. To bridge this gap, we sought to functionally dissect NA9 activity using Drosophila. For this, we generated transgenic NA9 fly lines and expressed the oncoprotein during larval hematopoiesis. This markedly enhanced cell proliferation and tissue growth, but did not alter cell fate specification. Moreover, reminiscent to NA9 activity in mammals, strong cooperation was observed between NA9 and the MEIS homolog HTH. Genetic characterization of NA9-induced phenotypes suggested interference with PVR (Flt1-4 RTK homolog) signaling, which is similar to functional interactions observed in mammals between Flt3 and HOXA9 in leukemia. Finally, NA9 expression was also found to induce non-cell autonomous effects, raising the possibility that its leukemia-inducing activity also relies on this property. Together, our work suggests that NA9 ability to induce blood cell expansion is evolutionarily conserved. The amenability of NA9 activity to a genetically-tractable system should facilitate unraveling its molecular underpinnings.

Induction of hemocyte apoptosis by Ovomermis sinensis: Implications for host immune suppression.

The entomopathogenic nematode, Ovomermis sinensis, is a parasite of some common lepidopteran pests. O. sinensis is able to overcome the immune system of its hosts and eventually kill the hosts when it emerges. We provide insight into how the mermithid nematode overcomes the immune response of the host Helicoverpa armigera. Our results indicate that O. sinensis actively inhibits host immune responses as evidenced by hemocyte nodulation, spreading behavior, lysozyme activity and melanization. However, O. sinensis did not inhibit host immune responses through immune gene activation. Moreover, the research on the immune depressive strategies of O. sinensis revealed that the parasite did not inhibit host effector molecules, but did reduce the number of hemocytes. Flow cytometry analysis revealed that the host hemocytes were apoptotic within 24 h, and no hemocytes were present after 72 h. In addition, our in vivo and in vitro studies showed that the survival rate of O. sinensis was increased when hemocyte proliferation was inhibited. Our findings suggest that O. sinensis inhibited host immune responses by inducing apoptosis of host hemocytes.

Genomic abnormalities affecting mussels (Mytilus edulis-galloprovincialis) in France are related to ongoing neoplastic processes, evidenced by dual flow cytometry and cell monolayer analyses.

In the context of the abnormal mass mortality of mussels in France since 2014, Flow CytoMetry (FCM) was used in 2015 and 2016 to study the DNA content and cell cycle characteristics of hemic circulating cells collected from 2000 mussels. The mussels were sampled from 12 wild and cultivated blue mussels stocks distributed along the French Atlantic coast from the south Brittany to Pertuis Charentais areas. During these surveys, various genetic abnormalities were frequently detected, and ploidy characteristics revealed contrasting profiles that corresponded to respective contrasting sanitary status, i.e. healthy mussels with high cytogenetic quality (HCQ) versus diseased mussels with low cytogenetic quality (LCQ). In the present work, FCM and hemocytology cell monolayer techniques were combined in order to determine the putative causes of the observed genetic abnormalities that were significantly associated with mortality levels. FCM and cell monolayer approaches permitted the definition of new threshold values delimiting HCQ mussels from LCQ ones. FCM histograms of mussels from the HCQ group showed one single or a largely dominant population of diploid (2n) nuclei and a large majority of normal hemocytes. Hemolymph cell-monolayer analyses showed predominantly acidophil granulocytes characterized by nuclei of normal size and a large cytoplasm with numerous granulations. In contrast, FCM histograms for the LCQ group showed, in addition to the normal diploid (2n) nuclei, populations of nuclei that displayed aneuploidy patterns in a broad ploidy range, including diploid-triploid (2-3n), tetraploid-pentaploid (4-5n) and heptaploid-octaploid levels (7-8n). The corresponding hemolymph cell-monolayer showed cellular features characteristic of disseminated neoplasia disease with frequent abnormal anaplastic cells that exhibited noticeable numbers of mitotic figures with both normal and aberrant chromosomes segregation patterns. These neoplastic cells were a rounded shape with a reduced, granulation-free cytoplasm and large (11-12 µm) to very large (up to 21 µm) round or ovoid nuclei that correspond to the 4-5n and 7-8n nuclei previously detected by FCM analyses. These characteristics suggest that the genetic abnormalities detected by means of FCM were related to an ongoing neoplastic process that is affecting blue mussels in France, at least since the onset in 2014 of the mortality that heavily impacted French blue mussels stocks.

Effect of exposure time, particle size and uptake pathways in immune cell lysosomal cytotoxicity of mussels exposed to silver nanoparticles.

Cytotoxicity evaluation of hemocytes (lysosomal membrane stability [LMS] assay) from Mytilus galloprovincialis Lamarck, exposed to a sublethal dose (100 µg/L) of two size of silver nanoparticles (AgNPs: <50 nm and <100 nm) - prior to and after inhibition of potential uptake pathways (i.e., clathrin- and caveolae-mediated endocytosis) within different times of exposure (3, 6, 12 h) - showed that there was a significant cytotoxic effect on immune cells of mussels exposed for different times to either AgNP size (p < 0.01); the greater effect was with the smaller size. However, hemocytes seemed more sensitive to the larger AgNP after clathrin-mediated endocytosis was blocked (p < 0.01); this was not so with inhibition of caveolae-mediated endocytosis. Dimethyl-sulfoxide (DMSO) did not impart a carrier-mediated effect despite an enhanced cytotoxicity when DMSO was present with AgNP. From these results, it is concluded that the immunotoxicity of AgNP in mussels was size-dependent as well as length of exposure-dependent. It was also clear that nanoparticles (NP) internalization mechanisms were a major factor underlying any toxicity.

Histological Alterations in Pacific Oysters Crassostrea gigas that Survived a Summer Mortality Event in Baja California, Mexico.

A mortality episode (>90%) of triploid and diploid Pacific oysters Crassostrea gigas cultured in Baja California Sur occurred during summer 2012, coinciding with a thermal anomaly, an algal bloom, and low oxygen values. To help explain the cause of the mortalities, histological analyses and molecular tests for specific pathogens (ostreid herpesvirus 1 [OsHV-1] and Perkinsus marinus) were performed on oysters surviving at the end of the episode. Triploid oysters showed a high percentage of males (43%) and hermaphrodites (30%); 93% of these oysters were in the gonadic reabsorption stage, and in some cases, hemocytes completely filled the lumen of the gonadic follicles. Oysters presented large areas with severe hemocyte infiltration that extended toward the digestive gland. Diploid oysters showed similar gonad alterations. None of samples showed histological or molecular evidence of OsHV-1 or P. marinus. Histological alterations can be related to physiological disorders caused by the mechanism driving summer mortality. This is the first case history of a summer mortality episode among Pacific oysters in Mexico.

Transcriptional and cellular effects of paracetamol in the oyster Crassostrea gigas.

Acetaminophen (paracetamol) (PAR) is one of the most popular non-steroidal anti-inflammatory drugs (NSAIDs) with analgesic and antipyretic properties consumed worldwide and often detected in the aquatic environment. Due to the fact that PAR induces oxidative stress in mammals, the aim of this study was to evaluate if similar effects were observed in oysters Crassostrea gigas, given their economic and ecological importance and worldwide distribution. Oysters were exposed for 1, 4 and 7 days to two different sublethal PAR concentrations (0, 1 and 100µgL-1). Cell viability, DNA damage in hemocytes and enzymatic activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidases (GPx), glutathione reductase (GR), glucose 6-phosphate dehydrogenase (G6PDH) and glutathione S-transferases (GST) were evaluated in oyster gills. In addition, changes at transcriptional level of Cu/Zn superoxide dismutase (SOD), catalase-like (CAT-like), cytochrome P450 genes (CYP30C1, CYP2AU2, CYP3071A1, CYP356A1), glutathione S-transferase isoforms (GST-ω and GST-π-like), cyclooxygenase (COX), fatty acid binding proteins-like (FABP-like), and caspase genes were evaluated in oyster gills and digestive gland. No changes in cell viability and DNA damage were observed in oysters exposed to both PAR concentrations. Similarly, no significant changes were detected in the major antioxidant enzymes (except for auxiliary enzyme GR) in oyster gills, suggesting that changes in GR activity are enough to counteract a potential oxidative stress in C. gigas gills under these experimental conditions. Furthermore, changes at transcriptional level are concentration and tissue dependent. PAR elicited an inhibition of CYP30C1, CYP3071A1 and FABP-like transcripts highlighting their role in drug metabolism, transport and detoxification of PAR in the gills. GST transcript levels were type, tissue and concentration-dependent. GST-π-like was down-regulated in oyster gills exposed to the lowest PAR concentration and up-regulated in the digestive gland of oysters exposed to the highest PAR concentration. However, GST-ω transcript levels were lower only in oysters digestive gland exposed to the lowest PAR concentration. Therefore, changes at transcriptional level were more sensitive to assess the exposure to PAR at environmental relevant concentrations.

Are CuO nanoparticles effects on hemocytes of the marine scallop (Chlamys farreri) caused by particles and/or corresponding released ions?

Manufactured nanoparticles (NPs) have become emerging pollutants and attracted extensive concern about their potential effects on the marine environment. However, the contribution of particles and their corresponding released ions to the overall toxicity of CuO NPs is poorly understood. In this study, we investigated the toxicological effects of CuO NPs and their corresponding released ions on the hemocytes of Chlamys farreri. Both copper species induced membrane damage, and increased lysosome contents in hemocytes. Based on the integrated biomarker responses method, the relative contributions of particles (NPparticle) and dissolved ions (NPion) to the toxicity of CuO NPs after 2h of exposure were 62.07% and 37.93%, respectively, indicating that the particles rather than the dissolved ions were the dominant source of NP toxicity. Transmission/scanning electron microscopy analysis confirmed the greater histopathological effects exerted by particles than Cu ions. Higher reactive oxygen species (ROS) generation induced by NPparticle than by NPion suggested that the intracellular ROS production might be responsible for the NP toxicity. Our findings suggest that particles effects play a key role in risk assessment of CuO NPs on the marine ecosystem.

Gα73B is a downstream effector of JAK/STAT signalling and a regulator of Rho1 in Drosophila haematopoiesis.

JAK/STAT signalling regulates many essential developmental processes including cell proliferation and haematopoiesis, whereas its inappropriate activation is associated with the majority of myeloproliferative neoplasias and numerous cancers. Furthermore, high levels of JAK/STAT pathway signalling have also been associated with enhanced metastatic invasion by cancerous cells. Strikingly, gain-of-function mutations in the single Drosophila JAK homologue, Hopscotch, result in haemocyte neoplasia, inappropriate differentiation and the formation of melanised haemocyte-derived 'tumour' masses; phenotypes that are partly orthologous to human gain-of-function JAK2-associated pathologies. Here we show that Gα73B, a novel JAK/STAT pathway target gene, is necessary for JAK/STAT-mediated tumour formation in flies. In addition, although Gα73B does not affect haemocyte differentiation, it does regulate haemocyte morphology and motility under non-pathological conditions. We show that Gα73B is required for constitutive, but not injury-induced, activation of Rho1 and for the localisation of Rho1 into filopodia upon haemocyte activation. Consistent with these results, we also show that Rho1 interacts genetically with JAK/STAT signalling, and that wild-type levels of Rho1 are necessary for tumour formation. Our findings link JAK/STAT transcriptional outputs, Gα73B activity and Rho1-dependent cytoskeletal rearrangements and cell motility, therefore connecting a pathway associated with cancer with a marker indicative of invasiveness. As such, we suggest a mechanism by which JAK/STAT pathway signalling may promote metastasis.

Field and laboratory transmission studies of haemic neoplasia in the soft-shell clam, Mya arenaria, from Atlantic Canada.

A two-year laboratory and field study was initiated in 2001 in response to mass mortalities associated with haemic neoplasia (HN) in 1999 in Prince Edward Island (PEI) soft-shell clams, Mya arenaria. A laboratory proximity experiment (cohabitation) and an inoculation challenge were conducted with clams and mussels (Mytilus edulis). Three field exposure experiments were also conducted, in which naive clams were held in sediment (in trays) or out of sediment (in mesh bags) at three high HN prevalence sites on PEI. There was a conversion to HN positive in clams in the proximity experiment and in clams injected with whole blood and cell-free homogenate, but not at statistically significant levels. No mussels or control clams became HN positive. There was a significant conversion to HN positive in as little as 24 and 58 days after transfer with clams held out of sediment and in sediment, respectively. The laboratory and field experiments' results suggest that HN-infected clams are spreading the disease through water from infected clams to naïve individuals and via transplantation from affected to unaffected sites. Some environmental conditions (e.g. abnormally high water temperature and hypoxia-induced sea lettuce [Ulva lacteus] invasion) may make clams susceptible to infections or exacerbate the proliferation of HN.