Mechanisms of phenanthrene toxicity in the soil invertebrate, Enchytraeus crypticus

Abstract

Polycyclic aromatic hydrocarbons (PAHs) continue to cause environmental challenges as a result of their release into the environment by a great variety of anthropogenic activities and their accumulation in soils. Studies were conducted on the toxicological effect of the model PAH phenanthrene using the soil invertebrate model Enchytraeus crypticus at the individual, tissue, and molecular levels. Animals were exposed for 2 d and 21 d to phenanthrene concentrations corresponding to the (previously estimated) 3-wk effective concentration, 10% (EC10) and EC50 for effects on reproduction. Gene expression profiling did not reveal a typical phenanthrene-induced biotransformation signature, as it usually does in arthropods and vertebrates. Instead, after 2 d of exposure, only general metabolic processes were affected, such as translation and adenosine triphosphate synthesis-coupled electron transport. Histological sections of tissues of 2-d exposed animals showed no deviations from control. In contrast, after prolonged exposure of up to 21 d, histopathological effects were found: chloragogenous cells were highly vacuolated and hypertrophic. This was corroborated by differential expression of genes related to immune response and oxidative stress at the transcriptomic level. The data exemplify the complexity and species-specific features of PAH toxicity among soil invertebrate communities, which restricts read-across and extrapolation in the context of soil ecological risk assessment. Environ Toxicol Chem 2016;35:2713-2720. © 2016 SETAC.

Temperature-Dependent Toxicokinetics of Phenanthrene in Enchytraeus albidus (Oligochaeta)

“…Due to their lipophilic nature, PAHs may accumulate in organisms. The cytochrome P450 oxygenases and transferases of the phase I and phase II biotransformation systems of organisms can transfer PAHs into more water-soluble metabolites, which are eliminated from the body by transporters. , PAHs and their metabolites are directly harmful to soil communities by accumulating in soil biota . The toxicokinetics of PAHs has been investigated in both aquatic and terrestrial organisms, but with most focus on aquatic invertebrates and fish. − Much less is known on the uptake and elimination of PAHs in terrestrial invertebrates, such as the enchytraeid, Enchytraeus albidus …”

Analysis of phenanthrene degradation by Ascomycota fungi isolated from contaminated soil from Reynosa, Mexico

“…Phenanthrene (PHE) is the smallest PAHs with carcinogenic characteristics, which is used as a degradation study model (Roelofs et al . 2016). In this context, different researches have identified: new bacteria with high degradation activity of PAHs (Toledo et al .…”

“…2014; Roelofs et al . 2016). Based on this, in this work, different fungal strains of the phylum Ascomycota from the soil of the ‘La Escondida’ lagoon in Reynosa, Mexico were isolated and characterized to determine their ability to degrade one of the main PAHs, PHE.…”

Bioaccumulation and Toxicity of Organic Chemicals in Terrestrial Invertebrates

“…Duan et al [164] found changes in ROS-scavenging enzymes (superoxide dismutase and catalase) in E. fetida after 14 days of exposure to benzo-[a]pyrene, but not lipid peroxidation at concentrations below 500 mg kg À1 d.w. For the same species and chemical, Ye et al [168] denoted an increase in superoxide dismutase and peroxidase activities and failure to reach a new homeostasis status after 56 days at 10 mg kg À1 d.w. Glutathione S-transferases alterations were reported for phenanthrene and fluorene in E. fetida [169]. Recent OMICS have highlighted important differences in toxicity pathways elicited by PACs to soil organisms, as shown by Roelofs et al [170] for F. candida and E. crypticus after exposure to phenanthrene. Whereas no strong induction of biotransformation pathways was observed in E. crypticus, upregulation of genes encoding all phases of biotransformation/detoxification (I/II/III) was found in F. candida.…”