Ancient Sturgeons Possess Effective DNA Repair Mechanisms: Influence of Model Genotoxicants on Embryo Development of Sterlet, Acipenser ruthenus. Gazo I, Franěk R, Šindelka R, Lebeda I, Shivaramu S, Pšenička M, Steinbach C. Int J Mol Sci. 2020 Dec 22;22(1):E6. doi: 10.3390/ijms22010006.
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.
Shah, M.A., Saito, T., Šindelka, R. et al. Novel technique for definite blastomere inhibition and distribution of maternal RNA in sterlet Acipenser ruthenus embryo. Fish Sci (2021).
The cleavage pattern of a vertebrate’s embryo is either holoblastic (complete) or meroblastic (partial). Sturgeon and other basal bony fishes represent a transition of the cleavage pattern. To understand the transition, it is essential to develop an effective technique for the inhibition of specific blastomere cleavage. So far, various studies have demonstrated that diatom-derived polyunsaturated aldehyde (PUA), 2,4-decadienal (DD)—a model aldehyde for experimental studies—adversely affects the developing embryos of several aquatic species. In this study, we employed DD for inhibition of cleavage of a definite blastomere in sturgeon embryos under various conditions. The effective treatment was found to be a combination of DD injection (0.01 v/v) and visible light (44.86–91.15 W m−2). Notably, DD injection or light irradiation alone cannot inhibit cleavage. Furthermore, spatial RNA localization analysis using quantitative polymerase chain reaction (qPCR)-tomography revealed that the localized pattern of selected maternal messenger ribonucleic acids (mRNAs) remained constant along the animal–vegetal (A-V) axis, which suggests that RNA localization is completed by the end of oogenesis and that early embryonic cleavage is not required for A-V asymmetry preservation.
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