The discovery of DNA molecules is considered the beginning of the study of genetic inheritance. In modern science, it is understood that chemical markings are bonded to key sections of the DNA that affect the way genes are read and can change how they respond to environmental factors.
A study from researchers at the University of California, Santa Cruz, demonstrated how common epigenetic modification can be passed down from the grandparents and exist for several generations (grandoffspring). The transgenerational epigenetic inheritance may explain how the experiences of parents and grandparents influence the health and development of the offspring.
Grandparents' Lifestyle and Diet Influence Future Generation
According to Science Alert, transgenerational epigenetic inheritance could be a route in which health, lifestyle or diet, and environment of grandparents affect the health and development of the next generation. The changes seem clear, but the mechanisms behind them are yet to be understood.
Epigenetic changes are molecular changes in the DNA that come in many forms. They are reversible and do not change the DNA but could influence how the body reads a DNA sequence. For example, the cell's machinery will not be able to decipher genes into proteins if they cannot access them due to the bulky molecules that stand in their way.
Winding long strands of DNA around major proteins are called histones that are tight enough to have a similar silencing effect. Most epigenetic changes are thought to be erased and reset after fertilization. Meanwhile, sperm and oocytes are reprogrammed to ensure normal development, and some epigenetic changes can escape reprogramming and be passed on to the next generation.
The study titled "Sperm-inherited H3K27me3 epialleles are transmitted transgenerationally in cis" published in the Proceedings of the National Academy of Sciences (PNAS) focused on a specific modification of histone protein that influences how DNA is packaged in the chromosomes.
This mark is called H3K27me3 which turns off or represses affected genes and is found in both humans and Caenorhabditis elegant, which are used in the study.
Professor emerita Susan Strome said that the results of the findings establish a cause-and-effect relationship between sperm-transmitted histone marks and gene expression and the development of offspring and grandoffspring.
Transgenerational Epigenetic Inheritance in Grandoffspring
The research team utilized C. elegans sperm and oocytes as a model for the study. The epigenetic mark H3K27me3 refers to the methylation of a specific amino acid in the histone H3, which makes DNA densely packed and the genes in that region become less accessible for activation.
Researchers observed a large range of developmental effects in the grandoffspring, according to a similar report from Genetic Engineering and Biotechnology News. These developmental effects include some worms that were completely sterile due to how chromosomes get distributed during cell division that produce the sperm and oocytes.
Researchers have been studying the transgenerational epigenetic inheritance in the roundworms for years and Strome said the newly reported research shows the culmination of their work in the field. They noted that other researchers have studied mammalian cells in culture and have reported similar results to their findings but those studies did not show the transmission across multiple generations.
The team explained that their findings in C. elegans mirror the findings in mammalian cells and imply a conserved mechanism for chromatin-baed regulation, providing one way in which epigenetics in the parental genome rapidly creates epigenetic variation in a population that is genetically identical.
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