Influence of Particle Size on Ecotoxicity of Low-Density Polyethylene Microplastics, with and without Adsorbed Benzo-a-Pyrene, in Clam Scrobicularia plana

This study investigated the ecotoxicological effects of differently sized (4–6 µm and 20–25 µm) low-density polyethylene (LDPE) microplastics (MPs), with and without adsorbed benzo-a-pyrene (BaP), in clam Scrobicularia plana. Biomarkers of oxidative stress (superoxide dismutase—SOD; catalase—CAT), biotransformation (glutathione-S-transferases—GST), oxidative damage (lipid peroxidation—LPO) and neurotoxicity (acetylcholinesterase—AChE) were analysed in gills and digestive glands at different time intervals for a total of 14 days of exposure. In order to have a better impact perspective of these contaminants, an integrated biomarker response index (IBR) and Health Index were applied. Biomarker alterations are apparently more related to smaller sized (4–6 µm) MPs in gills and to virgin LDPE MPs in the digestive gland according to IBR results, while the digestive gland was more affected by these MPs according to the health index.

Effect of pentagastrin and gastrin-17 on the secretory function of the gastric glands

The regulation of the digestive glands of the stomach and pancreas in the body of animals and humans is provided by peptides, most of which are in various molecular forms. 10 molecular forms of peptides of the gastrin group and 5 peptides of the cholecystokinin (CCK) group have been identified, containing in their structure from 4 to 56 amino acids, the physiological role of which has been little studied. It has been proven that the liver removes up to 85% of short-chain peptides of the gastrin (pentagastrin) and cholecystokinin (CCK-8) groups.

Titanium Dioxide Nanoparticles are Toxic for the Freshwater Mussel Unio ravoisieri: Evidence from a Multimarker Approach

The current work investigated the ecotoxicological effects induced by Titanium Dioxide (TiO2) nanoparticles (NPs), used at three different concentrations (C1 = 10 μg·L−1, C2 = 100 μg·L−1 and C3 = 1000 μg·L−1) in a laboratory experiment, on the freshwater mussel Unio ravoisieri. Biochemical analyses of gills and digestive glands revealed a stress-related disruption of the antioxidant system. The catalase activity and the rates of malonedialdehyde and hydrogen peroxide production were significantly higher in both organs following the exposure to TiO2 NPs and was concentration-dependent. In addition, based on the observed changes in acetylcholinesterase activity, it can be concluded that the disturbance threshold for the cholinergic system was less than 1 mg·L−1 of TiO2. Overall, the results suggest that the mussel Unio ravoisieri could be used as a sentinel species in monitoring surveys assessing the environmental impact of metallic nanoparticles in freshwater systems.

iTRAQ-Based Quantitative Proteomic Analysis Reveals Toxicity Mechanisms in Chlamys farreri Exposed to Okadaic Acid

Okadaic acid (OA), produced by dinoflagellates during harmful algal blooms, is a principal diarrhetic shellfish poisoning toxin. This toxin poses a potential threat to bivalves with economic values. To better understand the toxicity mechanism of OA to bivalves, in this study, oxidative stress biomarkers (superoxide dismutase, SOD; catalase, CAT; glutathione S-transferase, GST; malondialdehyde, MDA) and the expression of detoxification genes (heat shock protein 70, HSP70; heat shock protein 90, HSP90; cytochrome P450, CYP450) were assessed in the gills of scallops Chlamys farreri after 24 h, 48 h and 96 h exposure to OA. In addition, the digestive glands of scallops exposed to OA for 96 h were dissected for an iTRAQ based quantitative proteomic analysis. The results of OA exposure experiments showed that OA induces oxidative stress and significant enhancement of the expression of detoxification genes in scallops. The proteomics analysis revealed that 159 proteins altered remarkably in OA-treated scallops, and these proteins were involved in phagosomes, regulation of actin cytoskeleton, adherens junction, tight junction, and focal adhesion. Amino acid biosynthesis, carbon metabolism, pentose phosphate pathway, fructose and mannose metabolism in the digestive glands were also significantly impacted. Our data shed new insights on the molecular responses and toxicity mechanisms of C. farreri to OA.

Establishing Correlations Between Normal Pancreatic and Submandibular Gland Ducts

BACKGROUND. The objectives of this study were to evaluate the relationship between ductal morphometry and ramification patterns in the submandibular gland and pancreas in order to validate their common fractal dimension. METHODS. X-ray ductography with software-aided morphometry were obtained by injecting barium sulphate in the ducts of post-mortem submandibular gland and pancreas specimens harvested from 42 adult individuals. RESULTS. Three cases were excluded from the study because of underlying pathology. There was a significant correlation between the length of the main pancreatic duct (MPD) and the intraglandular portion of the right submandibular duct (SMD) (r = 0.3616; p=0.028), and left SMD (r = 0.595; p<0.01), respectively, but their maximal diameters did not correlate (r = 0.139 - 0.311; p>0.05). Both dimensions of the SMD showed a significant right-left correlation (p<0.05). The number of MPD side branches (mean=37) correlated with the number of side branches of left SMD, but not with the right one (mean = 9). Tortuosity was observed in 54% of the MPD, 32% of the right SMD, and 24% of the left SMD, with mutual association only between the two salivary glands. CONCLUSIONS. Although the length of intraglandular SMD and MPD correlate, other morphometric ductal features do not, thus suggesting a more complex relationship between the two digestive glands.

OIL EFFLUENT EXPOSURE INDUCED BIOCHEMICAL MODULATIONS IN SUBCELLULAR / TISSUES (CYTOSOL,MICROSOMES) OF FOOT, GILL AND DIGESTIVE GLANDS OF LAMELLIDENS MARGINALIS.

Sub-cellular fractions (cytosolic and microsomal) were prepared from the tissues (foot, gill and digestive gland) of freshwater mussel Lamellidens marginalis and were scrutinized to investigate the modulation of biochemical components (protein, carbohydrate and lipids) after exposure of sub-lethal concentrations of 1/4th (11.88 ppt) and 1/10th (8.55 ppt) of 96-hr LC 50 of oil effluent, and recovery period (depuration-without oil effluent) after seven days interval i.e., 1st, 8th, 15th 22nd and 30th days. At the end of 30th day, biochemical components in both exposure and depuration periods, were analysed from the tissues of mussels. The accumulation of oil effluent in the tissues gradually increased, when exposed to both sub-lethal concentrations of oil effluent and significantly and gradually decreased levels of protein, carbohydrate and lipid contents in the sub-cellular tissues of mussels were observed. During recovery period (without adding oil effluent), all depleted biochemical contents were recovered, increased, gradually, significantly from 30th day to Ist day (P<0.05) and one-way ANOVA showed progressive positive regression coefficient values (P<0.05) in all days. The enhanced and recovered levels of biochemical components in oil-exposed mussels demonstrate a well-established defense mechanism in mollusc, and this response offers the possibility of use as a biomarker for the early detection of oil pollution.

Molecular biomarker responses in the freshwater mussel Anodonta anatina exposed to an industrial wastewater effluent

Using a selection of molecular biomarkers, we evaluated responses in freshwater mussels (Anodonta anatina) exposed to effluent from an industrial wastewater treatment facility. The aims of this work were to (1) assess biomarkers of general toxicity under sublethal exposure to an anthropogenic mixture of chemicals, represented by an arbitrary effluent, and (2) evaluate the potential of A. anatina as a bioindicator of pollution. Adult mussels (n = in total 32; 24 males and 8 females) were exposed (96 h) in the laboratory to a fixed dilution of effluent or to a control treatment of standardized freshwater. Metal concentrations were in general higher in the effluent, by an order of magnitude or more, compared to the control. Toxic unit estimates were used as proxies of chemical stress, and Cu, Ni, and Zn were identified as potential major contributors (Cu> Ni > Zn). Six transcriptional (cat, gst, hsp70, hsp90, mt, sod) and two biochemical (AChE, GST) biomarkers were analyzed in two tissues, gills, and digestive glands. Out of the 16 responses (eight biomarkers × two tissues), 14 effect sizes were small (within ± 28 % of control) and differences non-significant (p > 0.05). Results did however show that (1) AChE activity increased by 40% in gills of exposed mussels compared to control, (2) hsp90 expression was 100% higher in exposed female gills compared to control, and (3) three marker signals (AChE in both tissues, and hsp70 in gills) differed between sexes, independent of treatment. Results highlight a need for further investigation of molecular biomarker variability and robustness in A. anatina.

Monitoring the Emergence of Algal Toxins in Shellfish: First Report on Detection of Brevetoxins in French Mediterranean Mussels

In France, four groups of lipophilic toxins are currently regulated: okadaic acid/dinophysistoxins, pectenotoxins, yessotoxins and azaspiracids. However, many other families of toxins exist, which can be emerging toxins. Emerging toxins include both toxins recently detected in a specific area of France but not regulated yet (e.g., cyclic imines, ovatoxins) or toxins only detected outside of France (e.g., brevetoxins). To anticipate the introduction to France of these emerging toxins, a monitoring program called EMERGTOX was set up along the French coasts in 2018. The single-laboratory validation of this approach was performed according to the NF V03-110 guidelines by building an accuracy profile. Our specific, reliable and sensitive approach allowed us to detect brevetoxins (BTX-2 and/or BTX-3) in addition to the lipophilic toxins already regulated in France. Brevetoxins were detected for the first time in French Mediterranean mussels (Diana Lagoon, Corsica) in autumn 2018, and regularly every year since during the same seasons (autumn, winter). The maximum content found was 345 µg (BTX-2 + BTX-3)/kg in mussel digestive glands in November 2020. None were detected in oysters sampled at the same site. In addition, a retroactive analysis of preserved mussels demonstrated the presence of BTX-3 in mussels from the same site sampled in November 2015. The detection of BTX could be related to the presence in situ at the same period of four Karenia species and two raphidophytes, which all could be potential producers of these toxins. Further investigations are necessary to understand the origin of these toxins.

Predicted No-Effect Concentration of Roundup in the Composition with Pharmaceutical Chlorpromazine or Heating Causes Similar Biochemical Disturbances in Bivalve Mollusk Unio Tumidus

The ability of bioindicators to reflect the specific impacts in complex exposures is unpredicted. This study aimed to track the particular effects of pesticide Roundup (Rn) and antipsychotic drug chlorpromazine (Cpz) on the mussel Unio tumidus at environmentally relevant mixtures. The mussels were treated by Rn (17 µg L−1), Cpz (18 µg L−1), mixture of Rn and Cpz at 18 oC (RnCpz) as well as by Rn at 25 oC (RnT). Digestive glands were examined after 14 days of exposure. The indexes of stress response (total antioxidant capacity, glutathione (GSH&GSSG), metallothioneins (MTSH and Zn-MT), protein carbonyls levels), and markers of metabolic and detoxication (CYP450 related (EROD), Glutathione S-transpherase (GST), cholinesterase, caspase-3, citrate synthase (CS) activities), lysosomal membrane integrity, and Zn level were analyzed. Mostly common responses of mussels were indicated as the increase of oxidative stress, MTSH (except Cpz-group), EROD and CS (except Rn-group) responses. Rn-group indicated almost no-effect or abnormal for expected symptoms effect. However, under the heating Rn caused the decrease of Zn accumulation and loss of lysosomal integrity. Cpz provoked major response diverseness: a decrease in Zn and GST levels and an increase in lysosomal integrity. Thus, complex exposures abolished the individual response traits. Summarising, the application of integrated indices has benefits when evaluating the effects of complex exposures.