Cellular composition of the black scorpionfish (Scorpaena porcus, L 1758) blood and head kidney under short-time acute exposure to hypoxia.

In the present work, we studied the effect of short-term acute hypoxia on the cellular composition of the blood and the head kidney of the black scorpionfish. Dissolved oxygen concentration was decreased from 8.5-8.7 mg O2 l-1 (normoxia) to 3-5 mg O2 l-1 (relative normoxia), 1-3 mg O2 l-1 (moderate hypoxia), and 0-1 mg O2 l-1 (acute hypoxia) within 1.5-2 h by bubbling of water with N2. Exposure period was 4 h, water temperature was adjusted to 14-16 °C, and photoperiod was 12 h (light). Short-time acute hypoxia induced a rapid release of blast and immature cells from the head kidney into the circulating blood of the black scorpionfish, which was associated with reduction in erythropoietic reserves in 2.5 times. The number of immature erythroid cells (pronormoblasts, basophilic and polychromatophilic normoblasts) significantly increased in blood, and the simultaneously relative decrease of the number of abnormal red blood cell (RBC) and the increase of the number of RBC ghosts (lysed RBCs) in circulating blood were observed. The significant correlation between methemoglobin concentration and the number of RBC ghosts was shown (R2 = 0.640 or r = 0.800). Hypoxia induced RBC swelling on 5-6% compared to control. The number of RBC ghosts in the blood is likely involved in the stimulation of erythropoietin production under hypoxia.

Protein kinase A activity and NO are involved in the regulation of crucian carp (Carassius carassius) red blood cell osmotic fragility.

Activation of the cAMP pathway by ß-adrenergic stimulation and cGMP pathway by activation of guanylate cyclase substantially affects red blood cell (RBC) membrane properties in mammals. However, whether similar mechanisms are involved in RBC regulation of lower vertebrates, especially teleosts, is not elucidated yet. In this study, we evaluated the effects of adenylate cyclase activation by epinephrine and forskolin, guanylate cyclase activation by sodium nitroprusside, and the role of Na+/H+-exchanger in the changes of osmotic fragility and regulatory volume decrease (RVD) response in crucian carp RBCs. Western blot analysis of protein kinase A and protein kinase G substrate phosphorylation revealed that changes in osmotic fragility were regulated via the protein kinase A, but not protein kinase G signaling pathway. At the same time, the RVD response in crucian carp RBCs was not affected either by activation of adenylate or guanylate cyclase. Adenylate cyclase/protein kinase A activation significantly decreased RBC osmotic fragility, i.e., increased cell rigidity. Inhibition of Na+/H+-exchanger by amiloride had no effect on the epinephrine-mediated decrease of RBC osmotic fragility. NO donor SNP did not activate guanylate cyclase, however affected RBCs osmotic fragility by protein kinase G-independent mechanisms. Taken together, our data demonstrated that the cAMP/PKA signaling pathway and NO are involved in the regulation of crucian carp RBC osmotic fragility, but not in RVD response. The authors confirm that the study has no clinical trial.

Toxic effect of mussel Mytilus galloprovincialis exposed to Ag-TiO2 and ZnTi2O4-TiO2 bicomponent nanoparticles.

Nanoparticles (NPs) are widely used in various fields, including antifouling paints for ships and industrial structures submerged in water. The potential impact of NPs on aquatic organisms, particularly their potential toxicity, is a significant concern, as their negative impact has been relatively poorly studied. In this study, we evaluated the effect of different concentrations of bimetallic Ag-TiO2 and ZnTi2O4-TiO2 NPs, which could potentially be used in antifouling coatings, on the hemocytes of the Mediterranean mussel Mytilus galloprovincialis. Hemocytes were exposed to NPs at concentrations of 0.1-1 mg/L for 1 and 2 h, and the production of reactive oxygen species (ROS), levels of DNA damage, and number of dead cells were measured. Exposure to Ag-TiO2 NPs at 1 mg/L concentration for 1 h suppressed ROS production in hemocytes and reduced the relative number of agranulocytes in cell suspensions, without inducing DNA damage or cell death. Exposure to ZnTi2O4-TiO2 NPs did not cause changes in the ratio of granulocytes to agranulocytes in suspensions, nor did it affect other functional parameters of hemocytes. However, after a 2 h exposure period, ZnTi2O4-TiO2 NPs (1 mg/L) significantly reduced the production of ROS by hemocytes. These findings suggest that Ag-TiO2 and ZnTi2O4-TiO2 NPs have low acute toxicity for marine bivalves.

Shift in hemocyte immune parameters of marine bivalve Mytilus galloprovincialis (Lamarck, 1819) after exposure to methane.

Methane are widely used in industry as an emerge source may be released significantly higher aquatic ecosystems due to gas seepages. In this study, short-term (90 min) methane effects on bivalve hemocytes were investigated using flow cytometry. Hemocyte parameters including hemolymph cellular composition, phagocytosis activity, mitochondrial membrane potential and reactive oxygen species (ROS) content were evaluated in the mussel Mytilus galloprovincialis (Lamarck, 1819) exposed to hypoxia (control group), pure methane and industrial methane (industrial hydrocarbon mixture). Comparison of biomarkers showed that the mussel was more sensitive to methane than to low oxygen concentration, supporting the effects of methane on the mussel's immune system. After exposure to pure and industrial methane, the number of granulocytes decreased dramatically and the levels of reactive oxygen species, mitochondrial membrane potential and phagocytosis capacity increased significantly. It was shown that the methane type-dependent effect was pronounced, with industrial methane leading to more pronounced changes.