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Research Project: Discovery and Development of Natural Products for Pharmaceutical and Agrochemical Applications II

Location: Natural Products Utilization Research

Title: Modulation of DNA methylation machineries in japanese rice fish (Oryzias latipes) embryogenesis by ethanol and 5-azacytidine

Author
item Dasmahapatra, Asok - University Of Mississippi
item Khan, Ikhlas - University Of Mississippi

Submitted to: Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/22/2015
Publication Date: 10/26/2015
Publication URL: http://handle.nal.usda.gov/10113/62578
Citation: Dasmahapatra, A.K., Khan, I.A. 2015. Modulation of DNA methylation machineries in japanese rice fish (Oryzias latipes) embryogenesis by ethanol and 5-azacytidine. Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology. Part C 179:174-183. DOI:10.1016/j.cbpc.2015.10.011

Interpretive Summary: Alcohol consumption by women during pregnancy often induces fetal alcohol spectrum disorder (FASD) in children. Molecular mechanism or prevention of FASD, other than women abstaining from alcohol drinking during pregnancy, is not known. FASD is regulated by both genetic and epigenetic mechanisms. Compared to genetic mechanisms, epigenetic mechanisms are enzyme based and reversible. Moreover, due to limitation of the use of synthetic anti-alcoholic drugs during pregnancy, our long term goal is to investigate on botanicals that have therapeutic potential for the treatment of alcoholism and thus FASD. We used Japanese rice fish (Oryzias latipes) as an animal model of FASD and focused on genes responsible for DNA methylation as epigenome modulator during development. Our study indicated that during development, dnmt3ba, mbd1b, mbd3a, mbd3b, and mecp2 followed distinct expression patterns, generally high mRNA copies in early phases (0-2 dpf) and significantly low mRNA copies prior to or after hatching. Both ethanol (concentration-dependent) and 5-azaC has potential to modulate the developmental rhythm of DNA methylation machineries in Japanese rice fish.

Technical Abstract: As a sequel of our investigations on the impact of epigenome in inducing fetal alcohol spectrum disorder (FASD) phenotypes in Japanese rice fish, we investigated on several DNA methylation machinery genes including DNA methyl transferase 3ba (dnmt3ba) and methyl binding proteins (MBPs), namely, mbdl b, mbd3a, mbd3b, and mecp2 at the message level. Studies were made during normal development, from 0 day post fertilization (dpf) to hatching, and also exposing the fertilized eggs to ethanol or DNMT inhibitor, 5-azacytidine (5-azaC). Our data indicate that during development, all these genes followed distinct expression patterns, generally high mRNA copies in early phases (0-2 dpf) and significantly low mRNA copies prior to or after hatching. Ethanol (100-500 mM, 0-2 dpf)is unable to alter dnmt3ba, mbd3a , mbd3b, and mecp2 mRNAs while mbdl b reduced significantly at higher concentrations (300-500 mM) on 2 dpf; additional four days (2-6 dpf) maintenance of these embryos in ethanol-free environment, on 6 dpf, showed high mRNA copies of all these genes in embryos pretreated with 400-500 mM ethanol. Continuous exposure of fertilized eggs in 300 mM ethanol, 0-6 dpf, showed significantly high mRNA copies only in MBPs. 5-azaC (2 mM) on 2 dpfis able to enhance only mbd3b mRNA. Removal of5-azaC and maintenance of these embryos in clean medium, 2-6 dpf, showed significantly enhanced mRNAs of these genes except mbd3a (unaltered) on 6 dpf. Our data indicate that both ethanol (concentration-dependent) and 5-azaC has potential to modulate the developmental rhythm of DNA methylation machineries in Japanese rice fish.