Epigenetics of Reproduction in Animals - Building the Most Complex Structure on Earth - page 60

daughter machine becoming operational and taking over its own development before
her assembly is completed ( Buckley, 2008 ).
Buckley's model displays an essential feature of the reproduction of multicellu-
lar animals: the zygote (egg cell in parthenogenetic organisms) develops according
to instructions provided parentally to gametes until the phylotypic stage, when the
controller of the embryo, the central nervous system (CNS) takes over not just further
development, but the growth and organogenesis of the animal until adulthood as well.
The eumetazoan “living machine” builds neither the complete machine nor the
machine in miniature, which by growing in size, becomes a fully operational and
replicating “machine” of its kind; nor does the parent insert an operating program
in it. Rather, it provides the epigenetic information for its Bauplan at the phylotypic
stage. At this stage, long before the construction of the “living machine” is complete,
the embryo possesses an awesome information-generating machine, the CNS, which
starts functioning and generating information for building its own species-specific
multicellular structure and its own operating program.
All the self-replicating machines proposed until today are vastly inferior to even
the simplest unicellular organism so far as sophistication, self-sufficiency, and relia-
bility are concerned. But this is not always adequately appreciated. The complexity of
metazoans is often reduced to the mechanisms of protein synthesis. So, for example,
in an intriguing topic called Decoding Reality , Vedral (2010) compares living systems
with von Neumann's machine consisting, in his view, of four basic components:
1. The protein-synthesizing machine.
2. The biological nanoengine (akin to the Xerox copier).
3. Enzymes that act as controllers switching the nanoengine on and off.
4. The DNA information set.
Vedral continues, “So we see DNA as key to this process, as it contains the blue-
print 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.”
Unfortunately, his comparison is not appropriate. First, he compares the living
system to a protein-synthesizing machine, as if proteins were building blocks of the
multicellular organism. Two centuries after Schwann and Schleiden, we know that
the basic unit of all multicellular organisms is the cell, not the protein. Hence, the
key to understanding the nature of multicellular systems is to understand how the
complex multicellular structure consisting of billions or even trillions of cells of
the most different types of structure and function arises from a single cell (egg cell or
zygote). Multicellular organisms, and unicellulars as well, are not bags of proteins.
They are supracellular structures where the spatial arrangement of cells of different
types follows strictly determined and highly complex patterns. The information of
trillions or quadrillions of bits used for erecting multicellular structures is larger by
several orders than all the information contained in all the nucleotide sequences of
the DNA.
Unlike unicellulars, metazoans do not produce copies of themselves. They pro-
duce specialized cells, eggs, and sperm cells equipped with epigenetic information,