Biophysically constrained cell type differentiation

By: James V. Kohl | Published on: August 13, 2016

Intrinsic limits to gene regulation by global crosstalk

A paradigmatic example is that of the aminoacyl transfer RNA synthetase1, which uses kinetic proofreading2 to load appropriate amino acids onto matching tRNAs. This and other examples—including DNA replication, ligand sensing3, protein–protein interactions4,5,6,7,8,9, recognition events in the immune system10,11 and molecular self-assembly12—indicate that biology places a large premium on the reduction of unintended ‘crosstalk’, a generic term that encompasses all potentially disruptive processes due to reactions between non-cognate substrates.

Reported as: Global crosstalk limits gene regulation

Although most of the biophysical constraints have been understood at the level of individual genetic regulatory elements, the researchers find that crosstalk is special: while it originates locally due to biophysical limits to molecular recognition, its cumulative effect only emerges globally.

My comment: That fact has been known to serious scientists for several decades. They decided to represent feedback loops in the context of their generic term ‘crosstalk,’ which allows them to continue to obfuscate what is known about biologically-based cause and effect.  ‘Crosstalk’ “…encompasses all potentially disruptive processes due to reactions between non-cognate substrates.” Feedback loops biophysically constrain the disruptive processes.
See: From Fertilization to Adult Sexual Behavior (1996)
See: Nutrient-dependent/pheromone-controlled adaptive evolution: a model (2013)

…the model represented here is consistent with what is known about the epigenetic effects of ecologically important nutrients and pheromones on the adaptively evolved behavior of species from microbes to man. Minimally, this model can be compared to any other factual representations of epigenesis and epistasis for determination of the best scientific ‘fit’.

See for comparison: Mutation-Driven Evolution (2013)

…genomic conservation and constraint-breaking mutation is the ultimate source of all biological innovations and the enormous amount of biodiversity in this world. In this view of evolution there is no need of considering teleological elements. (p. 199)

See also:  Feedback loops link odor and pheromone signaling with reproduction (2005)

It appears that GnRH neurons integrate a variety of information about the internal state of the animal and its external environment. At least 10,000 neurons in 26 different brain areas appear to transmit signals directly to GnRH neurons. Among these are areas involved in odor and pheromone processing, sexual behavior, arousal, reward, and other functions. This suggests that GnRH neurons are poised to modulate reproductive physiology and behavior in accordance with the overall state of the animal.
These studies also indicate that GnRH neurons are likely to influence numerous brain functions. They appear to transmit signals to as many as 30,000 or more neurons in 34 brain areas, consistent with previous studies showing GnRH+ fibers and GnRH receptors in multiple brain regions (Badr and Pelletier, 1987; Jennes et al., 1988; Jennes et al., 1997). BL+ neurons likely to receive synaptic input from GnRH neurons were seen in areas associated with numerous different functions, including odor and pheromone processing, sexual behavior, appetite, defensive behavior, motor programs, and the relay of information to higher cortical areas. These results may reflect a strategy wherein GnRH neurons can modify diverse functions in order to coordinate the internal state of the animal and its behavior with reproduction in order to optimize reproductive success.

My comment: Rarely do we see a book author pit his expertise, which is based on neo-Darwinian theory, against the claims of serious scientists like 2004 Nobel Laureate, Linda Buck, who co-authored: Feedback loops link odor and pheromone signaling with reproduction (2005). The fact that it took another decade for other theorists to realize the difference between a serious scientist and a theorist attests to the ignorance of those who still try to place their findings back into the context of ridiculous theories.

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