Effects of organic mercury on Mytilus galloprovincialis hemocyte function and morphology

Abstract

Filter-feeding organisms accumulate xenobiotics and other substances in their tissues. They can be useful as sentinel organisms in biomonitoring of the marine compartment. Bivalve cellular immunity is ensured by phagocytosis and cytotoxic reactions carried out by hemocytes in a network with humoral responses. These can be affected by chemical contaminants in water that can be immunosuppressors also at a low concentration increasing the sensibility to pathogens. This work is an attempt to individuate cellular markers for pollution detection, investigating the effect of methylmercury (CH3HgCl) at different concentrations on the activity and hemocyte morphology of the Mediterranean mussel, Mytilus galloprovincialis. We assessed the effect of three sub-lethal concentrations of the organometal on the cellular morphology, the efficacy of phagocytosis toward yeast cells, the alteration of the lysosomal membrane and the ability to release cytotoxic molecules. The results provide information on the alteration of hemocyte viability, modification of the morphological and cytoskeletal features and besides the cellular spreading, intrinsic ability of motile cells was used as a complementary investigation method. Exposure to the contaminant affected the percentage of phagocytosis and the phagocytosis index. Moreover, morphological and cytoskeleton alteration, caused by the pollutant, leads to reduced ability to incorporate the target and adhere to the substrate and the low ability of cells to retain neutral red could depend on the effects of methylmercury on membrane permeability. These results reinforce the use of the Mediterranean mussel as model for the evaluation of environmental quality in aquatic ecosystems integrating the novel information about hemocyte functions and morphology sensibility to organic mercury. Graphic abstract

Effect of Methylmercury Exposure on Bioaccumulation and Nonspecific Immune Respsonses in Hybrid Grouper Epinephelus fuscoguttatus × Epinephelus lanceolatus

“…Fish are usually exposed to MeHg through their feed (fish meal) and environmental water pollution [ 20 ]. The direct and indirect exposure of MeHg by fish can cause loss of appetite, brain damage, abnormal system development, cell necrosis, and the inhibition of respiratory burst activity, all of which affect the growth and immune response of fish and shellfish [ 21 , 22 , 23 , 24 ]. In this study, we evaluated data regarding the effect of MeHg exposure on nonspecific immune response and bioaccumulation in hybrid grouper.…”

“…In vitro approaches are used to observe the effects of MeHg exposure, particularly on nonspecific immune responses of aquatic species including phagocytic activity and O 2 − production rate. A relevant study demonstrated that Mediterranean mussel ( Mytilus galloprovincialis ) hemocytes incubated with 10 −7 , 10 −6 , or 10 −5 M of MeHg had phagocytic rates that decreased with the increase of MeHg concentration and resulted in cell death [ 24 ]. Moreover, European sea bass ( Dicentrarchus labrax ) head kidney leukocytes that were incubated in 0.0005, 0.005, 0.05, or 0.1 mM of MeHg had phagocytic rates and respiratory burst activity that were significantly lower than those of that study’s control group ( p < 0.05) [ 22 ].…”

Cross-Species Comparisons of Nanoparticle Interactions with Innate Immune Systems: A Methodological Review

“…Signal transduction protein, enzymes, AMPs (general and species-specific) Lysenin/Fetidin [141,170,192] CCF [181,244] mytilin, myticin, EPp [176,200] [231]…”

“…In some models, cell viability may also be studied by measuring metabolic activity through cell-permeable fluorescent reduction such as CTB or the colorimetric MTT. In some models the use of counter stain dye such as trypan blue or nigrosine [141,192] or the use of DNA-binding florescent dyes are alternative methods for assessing cell viability [150]. There are several methods available to measure the number of cells that are in the process of dying (apoptosis).…”

Does Thermal Stress Modulate the Biochemical and Physiological Responses of Ruditapes Decussatus Exposed to the Progestin Levonorgestrel?

“…Lysosomes are intracellular organelle containing various hydrolytic enzymes associated with endogenous macromolecules and chemicals catabolism and metals sequestration (Moore et al,2007). Lysosomal membrane is target of several environmental stress that provoke diminution of its integrity (Shaw et al, 2019;Parisi et al, 2021). Therefore, its usefulness in several biomonitoring exercises explained by its none destructive biomarker aspect and easeful measurement by the neutral red retention time assay (NRRT) (Lowe and Pipe, 1994).…”