Dear Dr. Manan Vishvas Desai,

Regulatory genetic networks are fundamental for proper cellular function, development, and adaptation. These regulatory networks are not considered essential for life because, for instance,

cells often have multiple regulatory pathways controlling the same process, providing a degree of redundancy. If one pathway is disrupted, another may compensate. Cells can sometimes tolerate changes in regulatory networks, adapting to new expression patterns. So in a way, cells have backup mechanisms.

You can put it this way that regulatory genetic networks are crucial for life, but not strictly "essential", though disruption of these networks can lead to severe consequences, including developmental defects and disease, they are not immediately life-threatening. But this won't be the case when it comes to core metabolic or structural genes because genes directly involved in fundamental cellular processes like DNA replication, protein synthesis, and energy production are considered essential and their absence would typically result in cell death.

So, the statement, "regulatory genetic networks are essential for genetics and thus for multicellular life but are not essential for life" is correct.

Regards,

Malcolm Nobre

Malcolm Nobre If i have understood your point correctly, then during evolution some fundamental networks proved to be essential which we now find them to be highly conserved but with increasing complexity, newer networks became crucial but not strictly essential as you have explained?

The statement that gene regulatory networks (GRNs) are not essential for life likely reflects the state of scientific understanding in 2005 (2003 - 2004 by the time the book was prepared), when comparative transcriptomics across diverse organisms was still in its infancy. At that time, most studies focused on model organisms, and we lacked the high-resolution transcriptome maps that are now available for a wide variety of taxa.

Today, it's widely accepted that regulatory networks are not only present in all domains of life but are central to their adaptive capacity and function. Beside the architecture and complexity of GRNs differ between prokaryotes and eukaryotes, both rely heavily on regulation to ensure survival, responsiveness, and fitness.