DNA epigenetic marks are linked to reproductive aberrations in amphipods

Abstract

Linking exposure to environmental contaminants with diseases is crucial for proposing preventive and regulatory actions. Upon exposure to anthropogenic chemicals, covalent modifications on the genome can drive developmental and reproductive disorders in wild populations, with subsequent effects on the population persistence. Hence, screening of chemical modifications on DNA can be used to provide information on the probability of such disorders in populations of concern. Using a high-resolution mass spectrometry methodology, we identified DNA nucleoside adducts in gravid females of the Baltic amphipods Monoporeia affinis, and linked the adduct profiles to the frequency of embryo malformations in the broods. Twenty-three putative nucleoside adducts were detected in the females and their embryos, and eight modifications were structurally identified using highresolution accurate mass data. To identify which adducts were significantly associated with embryo malformations, partial least squares regression (PLSR) modelling was applied. The PLSR model yielded three adducts as the key predictors: methylation at two different positions of the DNA (5methyl-2'-deoxycytidine and N 6 -methyl-2'-deoxyadenosine) representing epigenetic marks, and a structurally unidentified nucleoside adduct. These adducts predicted the elevated frequency of the malformations with a high classification accuracy (84%). To the best of our knowledge, this is the first application of DNA adductomics for identification of contaminant-induced malformations in field-collected animals. The method can be adapted for a broad range of species and evolve as a new omics tool in environmental health assessment.

Effects of Diclofenac on the Reproductive Health, Respiratory Rate, Cardiac Activity, and Heat Tolerance of Aquatic Animals

“…Toxic effects obtained for endpoints related to early life stages as embryos can be explained by the fact that early life stages such as embryos and juveniles of amphipods are several hundred times more sensitive to environmental stressors than adults during acute exposure (e.g., to oil products [Linden, 1976] or to cadmium [Arambourou et al, 2017]). The embryo state as an endpoint of the toxic effects of hazardous substances has been actively developed during recent decades, based on Baltic amphipods (Gorokhova et al, 2018; Sundelin & Eriksson, 1998). The aberrations as delayed or stopped development of embryos have been less highlighted and interpreted than the appearance of malformed embryos, which is considered to be a result of toxic effects of heavy metals and organic pollutants (Berezina et al, 2019; Strode et al, 2017).…”

“…Assessments of fecundity (number of eggs per clutch, or clutch size) and embryonic state in the amphipod G. fasciatus were performed according to the recommended methodology for assessing the quality of the environment in the Baltic Sea (Gorokhova et al, 2018; Sundelin et al, 2008). Immediately after the end of the exposure, G. fasciatus females were counted (to estimate survival) and anesthetized with carbonated water.…”

Coupled Application of Antioxidant Defense Response and Embryo Development in Amphipod Crustaceans in the Assessment of Sediment Toxicity

“…The embryo malformation frequency is expressed as the mean percentage of malformed embryos/female based on the analysis of marsupia of 50 gravid females (Sundelin et al ; Gorokhova et al ). Undifferentiated and dead embryos and unfertilized eggs were considered as other types of aberrations and were not used in calculation of the embryo malformation frequency.…”

“…In the Gulf of Finland part of the Baltic Sea, the embryo malformation frequency in field populations of the amphipods Gmelinoides fasciatus, Gammarus tigrinus, and Pontogammarus robustoides was used as a high biological level biomarker reflecting the combined effects of chemical pollution (trace metals and polycyclic aromatic hydrocarbons [PAHs]) and eutrophication (high dissolved phosphorus levels, hypoxia; Berezina et al ). As a result of these extensive studies, the use of reproduction disorders in amphipods has been recommended by the Helsinki Commission as a supplementary indicator of biological effects in field monitoring of hazardous substances in the Baltic Sea (Gorokhova et al ).…”