Biology Reference
In-Depth Information
Fig. 15.10 The approximate
correspondence between
the triadicity of the TRAL
model of life (Fig.
15.8
)
and the triadic metaphysics
of C. S. Peirce (1903)
Possibility
(
Firstness
)
Probability
(
Secondness
)
Environment
(
Thirdness
)
the activities of the C-triad) and their environmental conditions and carries
all the information that can be observed/measured about an organism
consisting of 2N cells, each cell endowed with n genes, that are organized in
space and time, including its morphology. Thus defined, PDFCS described by
the TRAL model is akin to the wave function in quantum mechanics (Herbert
1987, Morrison 1990).
10. The principle of dendrochronology is this: As the cells divide, the diameter of
the tree increases with time. Due to the dependence of the rate of cell divisions
on the temperature and other factors of the environment of the tree, the density
of cells in the tree varies with the seasons of the year - the highest density being
found every winter. So the ring structure of a tree results from the interactions
between two processes - the cell division (which is internal to the tree) and the
rotation of the Earth around the Sun (which is external to the tree). This principle
of dendrochronology may be generalized and extended to morphogenesis, since
a similar, although much more complex, process can account for the structures
visible on the cross section of the
Drosophila
embryos which are the results of
the interaction between the internal cell division/differentiation and the external
alterations of environment (including temperature, humidity, morphogen
gradients, etc.). Just as we can now read off the age (and the past environmental
conditions) of a tree from tree rings, so we should in principle be able to read off
the developmental and evolutionary history (or mechanisms) of
Drosophila
melanogaster
from the molecular and cellular architectonics of the
Drosophila
.
One unexpected result of the TRAL model is that it provides a clear visual
distinction between “possibility” and “probability”. Possibility is Firstness of Peirce,
probability is Secondness, and Environment is Thirdness by default (Sect.
6.2.2
)
(Fig.
15.10
):
15.7 Quorum Sensing in Bacteria and Cell-Cell
Communication Networks
Quorum sensing refers to the phenomenon exhibited by a group of bacteria that
expresses select sets of genes
if and only if
there are a sufficiently large number of
them around (hence “quorum”) to cooperatively accomplish a gene-encoded task
that cannot be accomplished by individual bacteria (Miller and Bassler 2001).
