Inheritance Between Generations is More than Genes #Science #Biology #Genetics

Mendelian genetics give the fundamental laws which tell us if mother was a pink flower and so was father then the progeny will be pink flowers.  If mother was a pink flower and father was a white flower then the chances of being pink or white are fifty/fifty.  That's the first year Biology view of genetics and this science doesn't controvert that but it adds a distinct ripple to the simple elegance of it.

Egg-cell of a female fruit fly with the egg cell in which H3K27me3 was made visible through green staining. This cell, together with the sperm, will contribute to the formation of the next generation of flies. In the upper right corner, a maternal and paternal pre-nucleus are depicted before their fusion during fertilization. The green colouration of H3K27me3 appears exclusively in the maternal pre-nucleus, indicating that their epigenetic instructions are inherited into the next generation.

Credit: MPI of Immunobiology a. Epigenetics/ F. Zenk

Science Daily:  Epigenetics between the generations: We inherit more than just genes

You need to get some way into the article before the function of H3K27me3 becomes clear but one thing is clear from the start that this does not fit with standard Mendelian genetics.

Ed:  it is a cool pic, tho

Yep and without the signs you could pass it off as a modern art which, in a way, it is.


The abstract:

We are more than the sum of our genes. Epigenetic mechanisms modulated by environmental cues such as diet, disease or our lifestyle take a major role in regulating the DNA by switching genes on and off. It has been long debated if epigenetic modifications accumulated throughout the entire life can cross the border of generations and be inherited to children or even grand children. Now researchers from the Max Planck Institute of Immunobiology and Epigenetics in Freiburg show robust evidence that not only the inherited DNA itself but also the inherited epigenetic instructions contribute in regulating gene expression in the offspring. Moreover, the new insights by the Lab of Nicola Iovino describe for the first time biological consequences of this inherited information. The study proves that mother's epigenetic memory is essential for the development and survival of the new generation.

- SD

That last part is astounding since we have a general perception of fifty percent inheritance from each parent but the Epigenetic contribution comes from the mother.


The reason Epigenetics matters:

In our body we find more than 250 different cell types. They all contain the exact same DNA bases in exactly the same order; however, liver or nerve cells look very different and have different skills. What makes the difference is a process called epigenetics. Epigenetic modifications label specific regions of the DNA to attract or keep away proteins that activate genes. Thus, these modifications create, step by step, the typical patterns of active and inactive DNA sequences for each cell type. Moreover, contrary to the fixed sequence of 'letters' in our DNA, epigenetic marks can also change throughout our life and in response to our environment or lifestyle. For example, smoking changes the epigenetic makeup of lung cells, eventually leading to cancer. Other influences of external stimuli like stress, disease or diet are also supposed to be stored in the epigenetic memory of cells.

- SD


Going deep on how much Epigenetics matters:

I have skipped past the methodology for experimentation with H3K27me3 and that's left for the interested student to review in the source article.

However, get this ...

When they had a closer look into the embryos, the team found that several important developmental genes that are normally switched off during early embryogenesis were turned on in embryos without H3K27me3. "We assumed that activating those genes too soon during development disrupted embryogenesis and eventually caused the death of the embryo. It seems, virtually, that inherited epigenetic information is needed to process and correctly transcribe the genetic code of the embryo," explains Fides Zenk.

- SD

Without mother's Epigenetics, the embryo isn't going to make it.


There's plenty more in the source article for the interested student and pursuing it is strongly advised for any with a near-term interest in going into the field of Genetics.