Final answer:
Methylated DNA is reset during gamete formation and after fertilization, a part of epigenetic reprogramming that ensures proper embryonic development. Environmental factors can influence epigenetic marks, affecting gene expression in offspring. Research in methylomics reveals that lifestyle can have transgenerational effects on DNA methylation patterns.
Step-by-step explanation:
Resetting Methylation in Offspring
During gamete formation and after fertilization, DNA methylation patterns are generally reset. This process is critical for the development of offspring and is a part of the epigenetic reprogramming that occurs to ensure that genes necessary for embryonic development are expressed appropriately. However, some imprinted genes retain their methylation marks, and these marks can be inherited from one generation to the next.
Environmental factors such as diet, smoking, and exposure to toxins can influence epigenetic marks. Such marks include DNA methylation and histone modifications, and these changes can affect the gene expression in offspring, potentially for multiple generations. It is also important to note that certain enzymes, like DNA methyltransferases and histone deacetylases (e.g., HDAC9), play pivotal roles in the addition or removal of these epigenetic marks.
Research on methylomics and chromatin remodeling has demonstrated that lifestyle and environmental factors can have transgenerational effects by altering DNA methylation patterns. These alterations may be reversed in some cases, for instance, by using drugs that maintain the demethylated and acetylated forms of DNA, thus keeping necessary gene transcription "on".