Emine TOPARSLAN, Levent MERCAN, Mehmet KURAN

Kalıtımın Epigenetik Boyutunda DNA Metilasyon Desenleri

Epigenetik terimi, genetik olarak özdeş bireylerdeki fenotipik farklılaşmayı açıklamak, genetiğin üzerinde veya genetiğe ek olarak işlev gören mekanizmaları tarif etmek için kullanılmaktadır. DNA metilasyonu, DNA dizilerinde CpG adacıklarındaki metil grubu bağlanmış sitozinleri ifade etmekte olup, enzimatik olarak gerçekleştirilmektedir. Metillenmiş sitozinler gen ifadesinin kontrolünde önemli rol oynamaktadır. Farklı metillenen bölgeler bakımından metilasyon deseninin belirlenmesi bu desenin çevresel etkilerle generasyonlar boyunca ne şekilde kalıtıldığı ile ilgili bilgi vermektedir. Metilasyon deseninin belirlenmesinde en çok kullanılan yöntemler, Metilasyona Özgü Polimeraz Zincir Reaksiyonu ve Bisülfit dizileme ile Southern Blotlama ve Birleştirilmiş bisülfit- kesim enzimi yöntemi prosedürleridir. Son yıllarda metilasyon desenlerinin gen ifadelenmesinde oynadığı kritik rolün anlaşılmasıyla birlikte hayvan ıslahında kullanılan DNA markör verilerinin, nükleotid dizilerine ek olarak, metilasyon deseni bakımından da değerlendirilmesi gerekliliğini işaret etmektedir. Bu çalışmada epigenetik kalıtım - DNA metilasyonu ilişkisi ile metilasyon desenlerinin tespitinde kullanılan yöntemler irdelenmiştir

DNA Methylation Patterns in Epigenetic Context of Inheritance

Epigenetic is the term used to define phenotypic differentiation between genetically identical inviduals, as well as to describe mechanisms which function over or beside genetics. Enzymatically occurring DNA methylation refers to methylated cytosines located in CpG islands of DNA sequences. Methylated cytosines play significant roles in control of gene expression. Identification of methylation patterns in terms of different methylated regions provide information about how this pattern is inherited through generations by environmental effects. Methylation Specific PCR and Bisulphide sequencing, Southern blotting and Combined Bisulphide Restriction Assay are the most applied techniques for identification of methylation patterns. Recently the discovery of the critical role of methylation patterns on gene expression underlines importance of evaluation of methylation patterns, in addition to DNA marker data which are used in animal breeding. This study reviewed the relationship between epigenetic inheritance and DNA methylation, and the methods used in the detection of methylation patterns

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