A Survey on the Distribution of Ovothiol and ovoA Gene Expression in Different Tissues and Cells: A Comparative Analysis in Sea Urchins and Mussels

Ovothiols are histidine-derived thiols produced by a variety of marine invertebrates, protists and bacteria. These compounds, which are among the strongest natural antioxidants, are involved in controlling the cellular redox balance due to their redox exchange with glutathione. Although ovothiols were initially reported as protective agents against environmental stressors, new evidence suggests that they can also act as pheromones and participate in fundamental biological processes such as embryogenesis. To get further insight into the biological roles of ovothiols, we compared ovothiol biosynthesis in the sea urchin Paracentrotus lividus and in the mussel Mytilus galloprovincialis, the two species that represent the richest sources of these compounds among marine invertebrates. Ovothiol content was measured in different tissues and in the immune cells from both species and the expression levels of ovoA, the gene responsible for ovothiol biosynthesis, was inferred from publicly available transcriptomes. A comparative analysis of ovothiol biosynthesis in the two species allowed the identification of the tissues and cells synthesizing the metabolite and highlighted analogies and differences between sea urchins and mussels. By improving our knowledge on the biological roles of ovothiols and pointing out the existence of sustainable natural sources for their isolation, this study provides the basis for future biotechnological investigations on these valuable compounds

Immune and Reproductive Biomarkers in Female Sea Urchins Paracentrotus lividus under Heat Stress

The functioning of the immune and reproductive systems is crucial for the fitness and survival of species and is strongly influenced by the environment. To evaluate the effects of shortterm heat stress (HS) on these systems, confirming and deepening previous studies, female sea urchin Paracentrotus lividus were exposed for 7 days to 17 degrees C, 23 and 28 degrees C. Several biomarkers were detected such as the ferric reducing power (FRAP), ABTS-based total antioxidant capacity (TAC-ABTS), nitric oxide metabolites (NOx), total thiol levels (TTL), myeloperoxidase (MPO) and protease (PA) activities in the coelomic fluid (CF) and mitochondrial membrane potential (MMP), H2O2 content and intracellular pH (pH(i)) in eggs and coelomocytes, in which TAC-ABTS and reactive nitrogen species (RNS) were also analyzed. In the sea urchins exposed to HS, CF analysis showed a decrease in FRAP levels and an increase in TAC-ABTS, TTL, MPO and PA levels; in coelomocytes, RNS, MMP and H2O2 content increased, whereas pHi decreased; in eggs, increases in MMP, H2O2 content and pHi were found. In conclusion, short-term HS leads to changes in five out of the six CF biomarkers analyzed and functional alterations in the cells involved in either reproductive or immune activities

Eco-interactions of engineered nanomaterials in the marine environment: Towards an eco-design framework

Marine nano-ecotoxicology has emerged with the purpose to assess the environmental risks associated with engineered nanomaterials (ENMs) among contaminants of emerging concerns entering the marine environment. ENMs’ massive production and integration in everyday life applications, associated with their peculiar physical chemical features, including high biological reactivity, have imposed a pressing need to shed light on risk for humans and the environment. Environmental safety assessment, known as ecosafety, has thus become mandatory with the perspective to develop a more holistic exposure scenario and understand biological effects. Here, we review the current knowledge on behavior and impact of ENMs which end up in the marine environment. A focus on titanium dioxide (n-TiO2) and silver nanoparticles (AgNPs), among metal-based ENMs massively used in commercial products, and polymeric NPs as polystyrene (PS), largely adopted as proxy for nanoplastics, is made. ENMs eco-interactions with chemical molecules including (bio)natural ones and anthropogenic pollutants, forming eco- and bio-coronas and link with their uptake and toxicity in marine organisms are discussed. An ecologically based design strategy (eco-design) is proposed to support the development of new ENMs, including those for environmental applications (e.g., nanoremediation), by balancing their effectiveness with no associated risk for marine organisms and humans

Short-Term Thermal Stress Affects Immune Cell Features in the Sea Urchin <i>Paracentrotus lividus</i>

Due to global warming, animals are experiencing heat stress (HS), affecting many organic functions and species’ survival. In this line, some characteristics of immune cells in sea urchins subjected to short-term HS were evaluated. Paracentrotus lividus adult females were randomly divided into three groups and housed in tanks at 17 °C. In two of these tanks, the temperatures were gradually increased up to 23 and 28 °C. Celomatic fluid was collected after 3 and 7 days. The coelomocytes were morphologically typed and evaluated for their mitochondrial membrane potential (MMP), lipoperoxidation extent (LPO), and hydrogen peroxide content (H2O2). Respiratory burst was induced by treatment with phorbol 12-myristate 13-acetate (PMA). HS caused a significant change in the coelomocytes’ type distribution. MMP increased in the 23 °C-group and decreased in the 28 °C-group at both 3 and 7 days. LPO only increased in the 28 °C-group at 7 days. H2O2 progressively decreased together with the temperature increase. Respiratory burst was detected in all groups, but it was higher in the 17 °C group. In conclusion, the increase in temperature above the comfort zone for this animal species affects their immune cells with possible impairment of their functions

Response to microplastic exposure: An exploration into the sea urchin immune cell proteome

It is now known that the Mediterranean Sea currently is one of the major hotspot for microplastics (MPs; &lt; 5&nbsp;mm) pollution and that the risks will be even more pronounced in the coming years. Thus, the in-depth study of the mechanisms underlying the MPs toxicity in key Mediterranean organisms, subjected to high anthropic pressures, has become a categorical imperative to pursue. Here, we explore for the first time the sea urchins immune cells profile combined to their proteome upon in vivo exposure (72&nbsp;h) to different concentrations of polystyrene-microbeads (micro-PS) starting from relevant environmental concentrations (10, 50, 103, 104&nbsp;MP/L). Every 24&nbsp;h, immunological parameters were monitored. After 72&nbsp;h, the abundance of MPs was examined in various organs and coelomocytes were collected for proteomic analysis based on a shotgun label free proteomic approach. While sea urchins treated with the lowest concentration tested (10 and 50 micro-PS/L) did not show the presence of micro-PS in any tissue, in the specimens exposed to the highest concentration (103 and 104 micro-PS) there was an internalisation of 9.75&nbsp;±&nbsp;2.75 and 113.75&nbsp;±&nbsp;34.5&nbsp;MP/g, respectively. Proteomic analyses revealed that MPs exposure altered coelomocytes protein profile not only compared to the control group but also among the different micro-PS concentrations and these variations are micro-PS concentration dependent. The proteins exclusively expressed in the coelomocytes of specimens exposed to MPs are mainly metabolite interconversion enzymes, involved in cellular processes, indicating a severe alteration of the cellular metabolic pathways. Overall, these findings provide new insights on the mode of action of MPs in the sea urchin immune cells both at the molecular and cellular level