Question

When does the erasure and reestablishment phase of genomic imprinting occur? Explain why it is necessary to erase an imprint and then reestablish it in order to always maintain imprinting from the same sex of parent.

Short answer

The erasure of genetic imprints happens during gametogenesis in primordial germ cells with the reestablishment occurring shortly after according to the sex of the individual. This process is critical for avoiding genetic conflicts, controlling gene expression, and ensuring healthy fetal development by enabling a unique combination of traits from both parents. The maintenance of imprinting from the same sex of parent allows each parent to contribute different and complementary sets of developmental instructions, which is necessary for healthy embryonic development.

Step-by-step solution

Explain the erasure and reestablishment phase

Genomic imprinting is the phenomenon by which certain genes are expressed in a parent-of-origin-specific manner. The phase of erasure and reestablishment happens during gametogenesis. The imprints are erased in primordial germ cells and then reestablished according to the sex of the individual, in the developing egg and sperm. This ensures that only the mother’s or only the father’s allele of specific genes is expressed.

Discuss the necessity of erasure and reestablishment

It is necessary to erase and reestablish genomic imprints in order to avoid conflict between maternal and paternal genes. This process is crucial for controlling gene expression and during development. The erasure of imprinting marks allows each parent to make an equal contribution to the offspring’s genome, and their reestablishment according to the sex of an individual ensures the specific parental pattern of genomic imprinting is accurately reset in each generation.

Discuss the necessity of maintaining imprinting from the same sex of parent

Maintaining imprinting from the same sex of parent plays a vital role in fetal development. This parental-specific gene expression enables each offspring to have a unique combination of traits, resulting in genetic variation, which is fundamental for survival and adaptation. Each parent contributes different, and complementary, sets of instructions for development. Having both sets of imprinted genes working correctly is vital for healthy embryonic development.