Some Genes Stayed Frozen for Millennia, Reveal Scientists at Yale – Genetic Education
Image of DNA used to show evolution and gene expression.

Some Genes Stayed Frozen for Millennia, Reveal Scientists at Yale

Our DNA is highly dynamic and sensitive to any sudden or long-term change. The effect appears either as a change in the DNA sequence or gene expression. The sequence-based alterations are abundantly studied. 

The gene expression studies lack a strong foundation as they may vary among cells, tissues, individuals and between different climates, locations and environments. 

Gene expression is when a gene produces a protein. But ‘in how much amount’ it produces a protein depends on many factors. Gene expression is highly dynamic and helps us adapt to the conditions locally and rapidly.  

It’s temporary, too. Each gene has its own expression profile and range. Within this range, it goes up and down and adjusts as per the requirement. However, the recent research conducted by the scientists of Yale School of Public Health reveals something interesting.  

Several genes’ expressions froze during the evolution of millions of years and remained unchanged. Dr. Jeffrey Townsend said,

“While genes adapt quickly and evolve their expression rapidly, some genes remain virtually frozen for hundreds to millions of Years.”  

Read more: How a Novel Epigenetic Regulator Impacts Gene Expression?

Now, the question here is, assessing an individual gene’s expression profile is nearly impossible and it becomes even unrealistic when we are talking about the entire evolutionary coverage.   

How did they do that? And concluded!

Townsend and team had experimented with nine different fungal species and analyzed 3,900 genes for their expression evolution. To tackle the highly dynamic nature of gene expression, they gave the same nutrients and conditions to each species. 

This, by means, is a nearly zero change applied during their growth phase. All samples have been nurtured in the same environment. 

They collected samples during different development stages and performed gene expression profiling. They have reported differential gene expression profiles during various sexual and asexual developmental stages. 

Here is something interesting that happened. 

Genes involved in the early fungal germination tend to be expressed in very high amounts. The reason is, the early development stage acquires nutrients faster and hence, grows at a rapid speed. 

In addition, it also needs to adapt to the local conditions and provide a foundation for cells to enter into a new life stage. 

This set of genes is under very high pressure to change. Contrary, the genes involved in sexual reproduction express differently. Their sophisticated statistical modeling showed that these genes (involved in germination) evolved rapidly during 6.9 million years. 

While for most other genes, the time range is between 400 to 900 million years. This study demonstrated that, 

Genes involved in common, responsive and flexible tasks are under higher evolutionary pressure and show rapid gene expression changes. Conversely, genes involved in crucial activities like meiosis (sexual reproduction) remain stable, mostly. 

Meaning, these genes are the ‘core heartbeat of life’ and can’t tolerate change. Thus, they are conserved. 

Read more: Recent Ancient DNA Study Solved the Mystery of the World’s Largest Amphibian.

It’s like when you migrate to the hotter and mountainous areas, genes associated with skin pigmentation, oxygen supply, sleep cycle, etc, change rapidly to adapt. But still, genes associated with vital organ development remain unchanged. 

In conclusion, evolution isn’t a uniform process for all genes. Essential and tightly regulated genes hardly change, while genes that need adaptation evolve much faster.

This groundbreaking study has been published in Molecular Biology and Evolution and helps solve the mystery of gene expression to some extent. Hoping for more research in the future to solve the mystery of gene expression. 

Source:

Yen-Wen Wang, Fen Wang, Guoliang Meng, Francesc Lopez-Giraldez, Caihong Dong, Zheng Wang, Jeffrey P Townsend, Rates of Evolution of Developmental Changes in Gene Expression in Sordariomycetes, Molecular Biology and Evolution, Volume 42, Issue 6, June 2025, msaf131, https://doi.org/10.1093/molbev/msaf131.

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