Epigenetics Comes of Age

In an extremely intriguing book, “Decoding Reality” (Oxford University Press, 2010) V. Vedral, among other things, compares living systems with the von Neumann’s machine consisting, in his description, of four basic components:- the protein synthesizing machine, M,- the biological nano-engine (akin to Xerox copier), X- enzymes which act as controllers switching the nano-engine on and off, C- the DNA information set.  “So we see -he says- DNA as key to this process, as it contains the blueprint of how each cell operates and replicates. Based on it, the constructor machine within our cells synthesizes amino acids, which in turn make up various proteins and new cells for our bodies.”

However intriguing, unfortunately, his comparison is confusing and groundless. First, he compares the living system with a protein synthesizing machine, as if proteins are building blocks of the multicellular organism. For about two centuries after Schwann and Schleiden biologists know that the basic unit of all multicellular organisms is the cell not proteins. Hence, the key to understanding the nature of multicellular systems is to understand how from a single cell (egg cell or zygote) arises the complex multicellular structure consisting of billions/trillions of cells of the most different types of structure and function, although they have all the same DNA. Multicellular organisms are not bags full of proteins but highly organized supracellular structures where the arrangement of cells of different types follows strictly determined and highly complex patterns of which the amazing diversity of multicellular forms arises.

The information of trillions/quadrillions of bits used for erecting multicellular structures is several orders larger than the whole amount of information contained not only in genes but in the whole nucleotide sequence of the DNA. That information is not encoded in the DNA or genes, which are known to possess no other type of information besides the genetic information for synthesizing proteins. Such a complex process as erection of a multicellular organism needs to be controlled and the controller can be anything but enzymes, which do not and cannot do anything besides catalysing specific biological reactions.

The question then arises: where the information for erecting supracellular structure comes from and which is the controller of the process of the developing of the multicellular structure starting from a single cell?

Eumetazoans at least, via egg cells/zygotes, provide to their offspring epigenetic information in the form of parental (maternal and paternal) cytoplasmic factors and gene imprinting for erecting the early structure of the phylotypic stage, which includes formation of an incipient but operational central nervous system. The latter takes over the development of the organism by generating and providing epigenetic ionformation for the whole post-phylotypic development up to adulthood. 

“Evolution of metazoans, and multicellular organisms in general, was a complex task that transcends the most courageous dreams of human genius. von Neumann dreamed of a machine (replicator) that would be able to build copies of its own when provided with necessary parts. The machine then would install and switch on the operating program in the completed daughter machine, which could then enter a self-repeating cycle of production of self-replicating von Neumann machines.  Even this over-ambitious dream of building a self-replicating machine looks much unsophisticated when compared with what actually a metazoan organism accomplishes during its lifetime.

In the case of the “living machine” the parent(s) builds neither the machine nor the machine in miniature that by growing in size would become a complete operating and replicating machine of its kind; nor does the parent insert operating program in it. It rather provides epigenetic information for building a rudimentary model of the adult form, the Bauplan at the phylotypic stage.

What is beyond the reach of even the wildest human imagination is that at the phylotypic stage the embryo is in possession of an awesome information-generating machine, the central nervous system, which starts functioning and generating information for building its own species-specific metazoan structure and its own operating program, long before the construction of “living machine” is completed.” (Cabej, N.R. 2008, Epigenetic Principles of Evolution, Albanet, pp. 28-29)

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