Animal Molecular Breeding 2024, Vol.14, No.1, 72-81 http://animalscipublisher.com/index.php/amb 73 1 Overview of Epigenetics 1.1 Basic concepts of epigenetics Epigenetics is a discipline that studies genetic variation in the process of regulating gene expression and inheritance through chemical modification, protein modification and other mechanisms without changing the DNA sequence of the cell's genetic material (Inbar-Feigenberg et al., 2013). In this field, this study not only explores the sequence of the gene itself, but also focuses on the expression state of the gene under specific conditions and the impact of the environment on this process. Gene expression refers to the process by which genetic information is transcribed into RNA and then further translated into protein. Epigenetics focuses on the regulation of gene activity in this process. By chemically modifying DNA and modifying proteins, cells can flexibly control gene expression levels, allowing different cells to exhibit different functions and characteristics with the same genome. Environmental factors have an important impact on gene expression, which is a key concept in epigenetics. External environments, such as nutrition, toxicant exposure, climate, etc., can affect cell function and individual phenotypes by changing the epigenetic state of genes. This response mechanism enables organisms to adapt to different environmental stresses and also triggers a series of regulatory processes at the epigenetic level. Cells will exhibit different phenotypes under specific conditions, and this phenotypic change is closely related to epigenetics. For example, during cell differentiation, stem cells can transform into specific types of cells through epigenetic regulatory mechanisms, exhibiting different morphologies and functions. The regulation of this phenotypic change is the basis for maintaining the functional diversity of tissues and organs in organisms. By in-depth understanding of the basic concepts of epigenetics, people can more fully understand the complexity of gene expression regulation in life, thereby providing a more in-depth theoretical basis for studying the epigenetic regulation mechanism in Pomeranians. 1.2 Types of epigenetic regulation Epigenetic regulation encompasses multiple complex mechanisms, including DNA methylation, histone modifications, and the role of non-coding RNAs. These regulatory mechanisms work together to maintain the balance of gene expression in synergy, providing a sophisticated regulatory system for the development, adaptation, and expression of specific traits of organisms. DNA methylation is one of the core mechanisms in epigenetic regulation (Ma, 2023). It regulates gene activity by adding methyl groups to DNA molecules. In Pomeranians, this process plays a key role in cell differentiation, gene silencing, and chromosome stability. The mechanism of DNA methylation involves DNA methyltransferases, which are responsible for adding methyl groups to DNA molecules, thereby affecting gene expression. At the same time, the balance regulation between methylation and demethylation is also a complex and precise process, which is directly related to the spatiotemporal regulation of gene expression. Histone modifications are regulatory mechanisms by changing histone proteins on chromosomes. This process includes a variety of modifications, such as acetylation, methylation, and phosphorylation. These modifications directly affect chromosome structure and compactness, thereby regulating gene accessibility and expression levels. In Pomeranians, histone modifications may be involved in the expression and maintenance of specific traits, providing the molecular basis for their unique appearance and behavioral characteristics. Non-coding RNA is a type of RNA molecules that does not encode proteins, including microRNA and long non-coding RNA (Mattick and Makunin, 2006). These RNA molecules directly or indirectly regulate gene expression by binding to mRNA and interfering with protein synthesis. In Pomeranians, non-coding RNA may play an important role in nervous system development, immune regulation and other aspects. They participate in the formation and maintenance of dog breed-specific traits by interacting with other epigenetic regulatory mechanisms.
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