Location: Genomics and Bioinformatics ResearchTitle: Ethanol Disrupts Chondrification of the Neurocranial Cartilages in Medaka Embryos without Affecting Aldehyde Dehydrogenase 1A2 (Aldh1A2) Promoter Methylation) Author
Submitted to: Comparative Biochemistry and Physiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/22/2009
Publication Date: 11/15/2009
Publication URL: www.esevier.com/locate/cbpc
Citation: Hu, Y., Willett, K.L., Khan, I.A., Scheffler, B.E., Dasmahapatra, A.K. 2009. Ethanol Disrupts Chondrification of the Neurocranial Cartilages in Medaka Embryos without Affecting Aldehyde Dehydrogenase 1A2 (Aldh1A2) Promoter Methylation. Comparative Biochemistry and Physiology. 150(4):495-502. Interpretive Summary: Medaka can be used as a model fish species to study fish development and interactions with chemicals. Ethanol is known to have undesirable effects and a there is a series of genes that are influenced by the presence or absence of ethanol. Many of these genes are associated with the detoxification of ethanol. Therefore there is interest in understanding how these genes are regulated due to the presence of ethanol. This study examined one of the genes associated with ethanol detoxification and specifically examined if an important type of modification was occurring in the portion of the gene that regulates how it is expressed. The study revealed that this type of modification, methylation pattern, was not occurring.
Technical Abstract: Medaka (Oryzias latipes) embryos at different developmental stages were exposed to ethanol for 48 h, then allowed to hatch. Teratogenic effects were evaluated in hatchlings after examining chondrocranial cartilage deformities. Ethanol disrupted cartilage development in medaka in a dose and developmental stage-specific manner. Compared to controls, the linear length of the neurocranium and other cartilages were reduced in ethanol-treated groups. Moreover, the chondrification in cartilages, specifically trabeculae and polar cartilages, were inhibited by ethanol. To understand the mechanism of ethanol teratogenesis, NAD+: NADH status during embryogenesis and the methylation pattern of Aldh1A2 promoter in whole embryos and adult tissues (brain, eye, heart and liver) were analyzed. Embryos 6 dpf had higher NAD+ than embryos 0 or 2 dpf. Ethanol (200 or 400 mM) was able to reduce NAD+ content in 2 and 6 dpf embryos. However, in both cases reductions were not significantly different from the controls. Moreover, no significant difference in either NADH content or in NAD+: NADH status of the ethanol-treated embryos, with regard to controls, was observed. The promoter of Aldh1A2 contains 31 CpG dinucleotides (- 705 to + 154, ATG = + 1); none of which were methylated. Compared to controls, embryonic ethanol exposure (100 and 400 mM) was unable to alter Aldh1A2 promoter methylation in embryos or in the tissues of adults (breeding) developmentally exposed to ethanol (300 mM, 48 hpf). From these data we conclude that ethanol teratogenesis in medaka does not induce alteration in the methylation pattern of Aldh1A2 promoter, but does change cartilage development.