Tributyltin Induces the Tissue-Specific Stresses in Zebrafish, a Study in Various Tissues of Muscle, Gill and Intestine

Biofouling dynamics and antifouling innovations: Transitioning from traditional biocides to nanotechnological interventions

Biofouling is a common phenomenon caused by waterborne organisms such as bacteria, diatoms, mussels, barnacles, algae, etc., accumulating on the surfaces of engineering structures submerged under water. This leads to corrosion of such surfaces and decreases their moving efficiency. Conventional antifouling agents are synthetic chemicals which are hazardous to non-target species. Further, these agents are mixed with paints, releasing toxins in the water bodies that affect other organisms. Thus, the development of natural alternatives for anti-fouling chemicals is urgently needed. This review examines the development of environmentally friendly antifouling technologies, focusing on the switch from biocidal coatings that leach toxic elements like mercury and copper to sustainable substitutes such as hybrid, biomimetic, and nanotechnology-based antifouling solutions. Research also focuses on increasing antifouling properties and reducing environmental impact by incorporating natural antifouling agents and constructing hybrid coatings that include multiple technologies. The financial effects of implementing these new technologies compared to more conventional approaches highlight the significance of sustainable practices in the maritime industry. This thorough review sheds light on the state of antifouling technology. It recommends future research to maximize ecological compatibility and apply these advancements to broader applications.

TPT disrupts early embryonic development and glucose metabolism of marine medaka in different salinites

Triphenyltin (TPT) is an organotin compound frequently detected in coastal estuaries, yet studies on TPT's effects in regions with significant salinity fluctuations, such as coastal estuaries, are currently limited. To investigate the toxic effects of TPT under different salinity conditions, this study focused on marine medaka (Oryzias melastigma) embryos. Through early morphological observations, RNA-seq analysis, biochemical marker assays, and qPCR detection, we explored the impact of TPT exposure on the early embryonic development of marine medaka under varying salinities. The study found that TPT exposure significantly increased embryo mortality at salinities of 0 ppt and 30 ppt. RNA-seq analysis revealed that TPT primarily affects glucose metabolism and glycogen synthesis processes in embryos. Under high salinity conditions, TPT may inhibit glucose metabolism by suppressing glycolysis and promoting gluconeogenesis. Furthermore, TPT exposure under different salinities led to the downregulation of genes associated with the insulin signaling pathway (ins, insra, irs2b, pik3ca, pdk1b, akt1, foxo1a), which may be linked to suppressed glucose metabolism and increased embryonic mortality. In summary, TPT exposure under different salinities affects the early development of marine medaka embryos and inhibits glucose metabolism. This study provides additional data to support research on organotin compounds in coastal estuaries.

Tributyltin-induced oxidative stress causes developmental damage in the cardiovascular system of zebrafish (Danio rerio)

Tributyltin (TBT) can be used as an antifouling agent with anticorrosive, antiseptic and antifungal properties and is widely used in wood preservation and ship painting. However, it has recently been found that TBT can be harmful to aquatic organisms. In this study, to gain insight into the effects of TBT with respect to the development of the cardiovascular system in zebrafish embryos, zebrafish embryos were exposed to different concentrations of TBT solutions (0.2 μg/L, 1 μg/L, and 2 μg/L) at 2 h post-fertilization (hpf) TBT exposure resulted in decreased hatchability and heart rate, deformed features such as pericardial edema, yolk sac edema, and spinal curvature in zebrafish embryos, and impaired heart development. Expression of cardiac development-related genes (vmhc, myh6, nkx2.5, tbx5a, gata4, tbx2b, nppa) is dysregulated. Transgenic zebrafish Tg (fli1: EGFP) were used to explore the effects of TBT exposure on vascular development. It was found that TBT exposure could lead to impaired development of intersegmental vessels (ISVs), common cardinal vein (CCV), subintestinal vessels (SIVs) and cerebrovascular. The expression of vascular endothelial growth factor (VEGF) signaling pathway-related genes (flt1, flt4, kdr, vegfa) was downregulated. Biochemical indices showed that ROS and MDA levels were significantly elevated and that SOD and CAT activities were significantly reduced. The expression of key genes for prostacyclin synthesis (pla2, ptgs2a, ptgs2b, ptgis, ptgs1) is abnormal. Therefore, it is possible that oxidative stress induced by TBT exposure leads to the blockage of arachidonic acid (AA) production in zebrafish embryos, which affects prostacyclin synthesis and consequently the normal development of the heart and blood vessels in zebrafish embryos.

Whole-Transcriptome Analysis Reveals the RNA Profiles in Mouse Bone Marrow Mesenchymal Stem Cells or Zebrafish Embryos After Exposure to Environmental Level of Tributyltin

To understand the underlying molecular mechanisms, mouse bone marrow mesenchymal stem cells (BMSCs) and zebrafish embryos were exposed to the control group and Tributyltin (TBT) group (10 ng/L, environmental concentration) for 48 h, respectively. The expression profiles of RNAs were investigated using whole-transcriptome analysis in mouse BMSCs or zebrafish embryos after TBT exposure. For mouse BMSCs, the results showed 2,449 differentially expressed (DE) mRNAs, 59 DE miRNAs, 317 DE lncRNAs, and 15 circRNAs. Similarly, for zebrafish embryos, the results showed 1,511 DE mRNAs, 4 DE miRNAs, 272 DE lncRNAs, and 28 circRNAs. According to KEGG pathway analysis showed that DE RNAs were mainly associated with immune responses, signaling, and cellular interactions. Competing endogenous RNA (ceRNA) network analysis revealed that the regulatory network of miRNA-circRNA constructed in zebrafish embryos was more complex compared to that of mouse BMSCs.

Metagenomics analysis reveals the effects of norfloxacin on the gut microbiota of juvenile common carp (Cyprinus carpio)

Norfloxacin (NOR) is an early third-generation quinolone antibiotic that has been widely used in animal husbandry and aquaculture because of its bactericidal properties. As an emerging contaminant, NOR may have toxic effects on fish. This study assessed the chronic toxicity (6 weeks) of 0 (control group), 100 ng/L (environmental concentration), and 1 mg/L NOR to the gut microbiota of juvenile common carp (Cyprinus carpio) based on metagenomic sequencing. Metagenomic analysis revealed that the Proteobacteria, Bacteroidetes, Fusobacteria, Firmicutes, and Actinobacteria were the dominant bacteria in the gut of common carp. The relative abundance of Actinobacteria was highest in the control group. The alpha diversity of the environmental concentration NOR was significantly lower than the control group. Principal coordinates analysis (PCoA) indicated that the bacterial community between the different groups formed clear separate clusters. NOR exposure adversely could affect immune function and some substance metabolic pathways in the gut microbiota of common carp. Furthermore, environmental concentrations of NOR produce antibiotic resistance genes (ARGs) in the gut microbiota, enhancing resistance to drugs. In conclusion, environmental concentrations of NOR could alter the composition, structure, and abundance of ARGs in the gut microbiota, thereby affecting the intestinal health of fish.

Integrating transcriptome and physiological analysis to reveal the essential responses of Daphnia magna to antimony trioxide nanoparticle

Antimony (Sb) pollution has already posed a severe threat to the aquatic ecosystem. However, the toxicity mechanisms of Sb on aquatic organisms are far from being elucidated. One of the crucial questions remaining unresolved is the characterization of molecular toxicity of Sb(III). Transcriptomics profiling combined with physiological characterizations was applied to investigate the response of Daphnia magna to nano-size antimony trioxide (nATO) and its soluble Sb(III) counterpart antimony potassium tartrate (APT) in the present study. Both nATO and APT induced the formation of oxidative stress, enhanced the activities of anti-oxidative enzymes, altered the metabolism of xenobiotics, increased the concentration of hydrogen sulfide (H₂S) and nitric oxide (NO), and triggered the self-protection mechanisms such as ubiquitin-mediated proteolysis. In addition, nATO and APT caused damage to the nervous system of D. magna, inhibited its locomotion and nutrient uptake in a concentration-dependent manner. Moreover, nATO exposure enhanced the autophagy activity, reflected by the up-regulated expression of hypoxia-inducible factor-1α, calmodulin-dependent protein kinase-β, and inositol-requiring enzyme 1. The present study, for the first time, depicted a global map of cellular response to nATO, provided essential information on Sb(III) toxicity to aquatic organisms, and is of great significance to the development of Sb management strategies.

Effects of tralopyril on histological, biochemical and molecular impacts in Pacific oyster, Crassostrea gigas

Recently, the toxic effects of tralopyril, as a new antifouling biocide, on aquatic organisms have aroused widespread attention about the potential toxicity. However, the mechanism of tralopyril on marine mollusks has not been elaborated clearly. In this study, the histological, biochemical and molecular impacts of tralopyril on adult Crassostrea gigas were investigated. The results indicated that the 96 h LC50 of tralopyril to adult Crassostrea gigas was 911 μg/L. After exposure to tralopyril (0, 40, 80 and 160 μg/L) for 6 days, the mantle mucus secretion coverage ratio of Crassostrea gigas was increased with a dose-dependent pattern. Catalase (CAT) activity was significantly increased, amylase (AMS) activity, acid phosphatase (ACP) activity and calcium ion (Ca²⁺) concentration significantly decreased. Meanwhile, integrated biomarker responses (IBR) index suggested that higher concentrations of tralopyril caused severer damage to Crassostrea gigas. In addition, the mRNA expression levels of biomineralization related genes in the mantle were significantly upregulated. Collectively, this study firstly revealed the histological, biochemical and molecular impacts of tralopyril exposure on adult Crassostrea gigas, which provided new insights for understanding the toxicity of tralopyril in marine mollusks.

Transient developmental exposure to tributyltin reduces optomotor responses in larval zebrafish (Danio rerio)

This study determined the effects of transient developmental exposure to tributyltin (TBT), a well-known anti-estrogenic environmental endocrine disrupting compound, on visual system development of larval zebrafish (Danio rerio). Zebrafish were exposed to either 0.2 μg/L or 20 μg/L TBT for 24 h when they were aged 24 h postfertilization (hpf), 72 hpf, or 7 days (d)pf. Immediately after exposure, larvae were transferred to system water for seven days of recovery followed by behavioral testing (startle and optomotor responses) and morphological assessment. TBT-treated larvae displayed age-dependent changes in morphology characterized by delayed/reduced growth and susceptibility to exposure. TBT exposure reduced the number of larvae displaying optomotor responses regardless of age of exposure; eye diameter was also decreased when exposure occurred at 24 hpf or 7 dpf. Startle responses were reduced only in TBT-treated larvae exposed when they were 24 hpf, suggesting transient TBT exposure during the early larval period may cause vision-specific effects.