Ancient Sturgeons Possess Effective DNA Repair Mechanisms: Influence of Model Genotoxicants on Embryo Development of Sterlet, Acipenser ruthenus

Abstract

DNA damage caused by exogenous or endogenous factors is a common challenge for developing fish embryos. DNA damage repair (DDR) pathways help organisms minimize adverse effects of DNA alterations. In terms of DNA repair mechanisms, sturgeons represent a particularly interesting model due to their exceptional genome plasticity. Sterlet (Acipenser ruthenus) is a relatively small species of sturgeon. The goal of this study was to assess the sensitivity of sterlet embryos to model genotoxicants (camptothecin, etoposide, and benzo[a]pyrene), and to assess DDR responses. We assessed the effects of genotoxicants on embryo survival, hatching rate, DNA fragmentation, gene expression, and phosphorylation of H2AX and ATM kinase. Exposure of sterlet embryos to 1 µM benzo[a]pyrene induced low levels of DNA damage accompanied by ATM phosphorylation and xpc gene expression. Conversely, 20 µM etoposide exposure induced DNA damage without activation of known DDR pathways. Effects of 10 nM camptothecin on embryo development were stage-specific, with early stages, before gastrulation, being most sensitive. Overall, this study provides foundational information for future investigation of sterlet DDR pathways.

Transcriptome and Proteome Analyses Reveal Stage-Specific DNA Damage Response in Embryos of Endangered Sturgeon

“…We have previously shown that CPT exposure led to different levels of DNA damage and different malformation rates, depending on the stage of exposure [10]. Similarly, Ola exposure in the early stages of development led to decreased survival and hatching rate, whereas exposure after neurulation did not have a signi cant effect on sturgeon embryos.…”

“…We exposed sterlet (A. ruthenus) embryos to CPT and Ola at different stages of embryonic development. The results of CPT exposure on sturgeon embryo development have been described in detail in our previous study [10]. Therefore, we will only summarize here the effects of CPT on sterlet embryo viability, hatching rate, DNA integrity, and phenotype formation.…”

“…As previously described [10], the sterlets (BW, 0.5-2 kg; 12 females, 12 males) were reared in the aquaculture facility of the Research Institute of Fish Culture and Hydrobiology at the University of South Bohemia, Vodňany, Czech Republic. To induce ovulation, female sh were injected with carp pituitary extract powder dissolved in 0.9% (w/v) NaCl solution at an initial dose of 0.5 mg/kg of body weight.…”

“…The sterlet embryos in CPT 48-72 group showed no increased DNA fragmentation compared with the control. The images of the phenotypes observed following CPT exposure are presented elsewhere [10].…”

“…The compounds concentrations were selected based on the available literature data and our previous experiments [10,26]. We used nal concentrations of 10 nM CPT (Sigma-Aldrich, St Louis, MO, USA, CAS Number: 7689-03-4) and 20 µM Ola (Selleck Chemicals, Houston, TX, USA).…”