Theoretical contributions

An introduction to the emergence of an integrative unit in each moment of ontogeny (as an example, Cordón's model of the cell)

(A summary by the FIBE of the nature of the cell. Evolutionist Treatise of Biology. Part Two. Vol. I, 1990, pp. 315-399)

Introduction

During the five years from 1978 a 1983, Faustino Cordón made his fundamental theoretical contribution to achieving a model of the cell as an integrative unit, i.e. a model of how the cell unit (experience) emerges in each moment of the activity of the proteins of its soma, perceives the state of its environment (masses of water molecules with nutrient molecules) and governs it actively to its benefit.

Through a step-by-step study of the evolutionary changes of associations of proteins, Cordón induced the phylogenic process of the origin of the first cell from a highly evolved association of proteins. This outstanding association of proteins from which the cell unit originated formed a cell soma that must have been structured as a small cellular membrane. Evolutionist Treatise of Biology. Part Two. Volume I. (p. 1-293).

The model of the origin of the cell in its phylogeny also resolved the question of how the cell unit (experience) must emerge in each moment of the life of all cells as a direct effect of the coordinated action of the membrane proteins of its soma, though it has a different physical nature from the action of each of these proteins. Evolutionist Treatise of Biology. Part Two. Volume I.(p. 315-504).

In this introduction we briefly present some concepts of the model of the cell with which Cordón explained how the somatic proteins give origin pulsatilely to the cell unit (experience) without it perceiving them, and the somatic proteins take the cell unit (experience) as a guide to their activity, also without knowing of its existence. With this model of the cell, Cordón achieved his definitive interpretation of a level unit by showing in detail how a unit capable of perceiving and using the continuously changing state of its environment originates, from moment to moment, from a soma composed of units of a lower level.

A brief presentation of Cordón's model of the cell as an integrative unit -an agent that is linked to its changing environment through its soma- must begin by recalling that a fundamental contribution of his theory is that the integrative unit of the level immediately below that of the cell is the protein. This statement means that the soma of all cells is composed of their proteins, and that the origin and nature of the cell as a unit must be considered in terms of the coordinated actions of its somatic proteins.

We can point out four aspects of the cell that are implicit to its consideration as a unit of a level immediately above that of the protein:

• The cell soma must be composed of proteins.

• The cellular action (movement of water) must have a different physical nature from the action of the proteins of its soma (handling molecules one by one in still water), but it must result directly and integrally from the coordination of these protein actions.

A temporal analysis of the cellular pulsation

• For the cellular action to be the result of the actions of its somatic proteins, these proteins must establish a faster and more integrating coordination with each other (the cellular stimulus: a field of pH in the coordinated water of its phospholipids) than the coordination that consecutive proteins establish with each other (reception and emission of metabolites).

• The cell as a unit (as a physical field of pH) must also originate directly from the effect of the actions of the constituent proteins of its soma, and it must guide their actions.

We briefly discuss each of these points below.

1. The cell soma must be composed of proteins

According to Cordón, one must overcome the description of the cell as a solution of proteins, metabolites and other molecules, separated from their hydric environment by a lipoprotein membrane. We must consider the cell soma as being composed of proteins organized spatially beside each other in an orderly way and immersed -but not dissolved- in the intracellular hydric environment. This interpretation must be used for prokaryotic cells and mitochondria and for chloroplasts of eukaryotic cells, in all of which the data on composition and relative concentrations of metabolites and proteins -in addition to observation using cryofracturing techniques- indicate an orderly organization of proteins. The data on the structure of the hyaloplasm of eukaryotic cells also indicate that each of its differentiated zones is structured into cellular membranes composed of lipoproteins and cytoskeletal fibres, also of a protein nature, which serve as a support and motor system to the cellular membranes.

2. The cellular action (movement of water) is the integrated result of the activity of the proteins of the cell's soma

Considering the protein as an integrative unit led Cordón to conclude that the action of metabolic proteins must consist essentially in the recognition, management and chemical transformation of their specific molecules (metabolites) in still water. An introduction to the protein as a an integrative unit of the first biological level.

According to Cordón, as a global result of the activity of all metabolic proteins, there occurs an intracellular concentration of residual metabolites (CO2 in present-day cells) and, as a consequence, an osmotic gradient between the interior of the cell and its aqueous environment.

The coordinated activity of certain membrane proteins (presumably by moving their phospholipids through intermolecular forces) would alter the permeability of the cell, which would allow this gradient of metabolites to be renewed and cause the corresponding directed movement of water, thus attracting nutrient molecules. Thus, the cellular action (the management of flows of water with dissolved molecules) would be a direct result of the actions of the cell's metabolic proteins (the management of metabolites one by one in still, intracellular water), but it would have a different physical nature as an effect of the renewal of an osmotic potential.

However, according to the Cordón, for the permeability caused by the membrane proteins to establish a directed movement of water, the cellular action would have to be pulsatile. For the effect of the action of the metabolic proteins (the residual metabolites released into the still intracellular water) to be renewed as an osmotic gradient which creates a current of water that attracts nutrient molecules towards the cell, the cell's life would have to transpire in pulsations. In each cell pulsation, 1) the cell membrane would have to be impermeable to water during the entire time in which the metabolic proteins, as a consequence of their action, released residual metabolites into the still, intracellular water until a suitable concentration was produced; and 2) the membrane proteins specialized in a brief moment would have to coordinate themselves instantly (we will see how) and permeabilize the membrane to allow the osmotic gradient to be renewed quickly and effectively, causing a directed current of water carrying nutrient molecules towards the interior of the cell.

Relations between the basibions of a tetrad in the different times of a cellular pulsation

Thus, in the momentary pulsation from which all cells must emerge in all instants of their life, Cordón differentiated two stages:

1) A prolonged protein stage in which, as a result of the action of the metabolic proteins, there would be a gradual accumulation of residual metabolites in the still water in the interior of the cell, during which the membrane would have to be impermeable to water.

2) An instantaneous cell stage, in which the metabolic proteins would cease their action, the membrane proteins would create a sudden permeabilization and, consequently, a current of external water would penetrate the cell and attract new nutrient molecules towards its membrane.

The current explanation is limited to the passing of the nutrient molecules through the cell membrane without questioning how they reach it, so it is accepted that they do so by mere diffusion. For Cordón, as we will see, the cell is an active agent that, through the action of its somatic proteins, perceives the nutritional state of the surrounding water and tries out the intensity with which it should attract water with dissolved molecules for its maximum benefit.

Let us see some of the ideas of his proposal on the establishment of each cell pulsation.

3. For the somatic proteins to establish the cell action, they must be coordinated with a faster stimulus (a field of pH in the water crystal of their common phospholipids) than that of two contiguous proteins

For the cellular action to result from the actions of the somatic proteins, it is necessary that a set of these proteins establish a simultaneous coordination of a different and faster physical nature than the sequential coordination between contiguous proteins.

The cytoplasmic proteins are situated next to each other and coordinated through the orderly release and reception of specific metabolites.

The membrane proteins absorb phospholipids around them and maintain them in liquid crystal state that makes them extraordinary conductors of H+. We must point out that the physiological function of the lipid bilayers that organize the membrane proteins is unknown. Nevertheless, we venture to propose that the membrane proteins with the same physiological function could be coordinated with each other instantly if, through their phospholipids, they structured a common sector in the lipid bilayer of the cell membrane.

If each protein membrane of a set with the same cellular activity emitted or captured H+ to or from its phospholipids in a sector of the bilayer structured by the whole set, a field of H+ common to this set of proteins would be organized. The variation in the emission of H+ by a protein of the set would instantly cause a disturbance in the entire pH field that would be instantly perceived by the remaining proteins from their phospholipids, and each one of them would learn to respond to this perception with an appropriate action (increasing or inhibiting its own activity).

This coordination between membrane proteins, which is of a new physical nature (a common field of pH) would connect a greater number of proteins and do so more quickly than the coordination established sequentially between proteins. Cordón gave the name cellular stimulus to the common pH field organized by the phospholipids of a set of proteins serving the same function, which would allow pulsatile initiation and cessation of the action of the proteins to be coordinated instantly.

This coordination of a set of membrane proteins related through their phospholipids would allow them to act in unison, causing the sudden permeabilization of the membrane and the instantaneous renewal of the osmotic gradient, as a current of water that would attract new nutrient molecules towards the cell (the cellular action).

Although the cellular stimulus, as a field of pH, is exclusive to the cell because it is produced and perceived by the stimulative membrane proteins that are specialized in this, it is nothing new in nature as a general physical phenomenon, because the establishment of an electrical field reaches a whole level of inorganic reality that is previous to the cell, so when all pulsatile cellular stimuli stop occurring, they are lost in the general inorganic electrical field. (In present-day cells the existence of cellular stimuli would explain not only the instant variations in their metabolic organelles (mitochondria and chloroplasts) but also the sudden changes in all cellular functions in response to the presence or absence of their specific signal molecule).

Synthesis pathways

In Cordón's interpretation, during the prolonged protein stage of each pulsation, two different sets of membrane proteins (the efferent and afferent membrane proteins) would establish two types of cellular stimuli: the efferent cellular stimulus and the afferent cellular stimulus.

1) During each prolonged protein stage, a set of efferent membrane proteins coordinated in unison by a common pH field would stimulate through H+ a set of metabolic proteins, which would produce a concentration of residual metabolites proportional to this stimulus (CO2 in present-day cells). The membrane proteins would organize the efferent cellular stimulus, which would reflect the intensity of the action that the cell was going to perform in that pulsation.

2) A set of proteins that control reserve metabolites would stimulate through H+ a set of afferent membrane proteins, which would allow the afferent proteins to reflect the movement of reserve in each pulsation. According to the amount of nutrients captured in the previous pulsation, it could happen that in order to establish the action that the cell has decided in the present pulsation, 1) there was no movement of reserves, 2) there was an accumulation of reserves, or 3) there was a mobilization of reserve. The membrane proteins, stimulated by the reserve metabolic proteins, would organize the afferent cellular stimulus, which would reflect the real state of the environment in the previous cell pulsation, proportional to the movement of reserve in the present one.

If, during the prolonged protein stage of each pulsation, the cell soma had a set of efferent membrane proteins, coordinated simultaneously, that imposed the intensity of the action on the metabolic proteins, and it had another set of membrane proteins, coordinated simultaneously, that (through the movement of reserve) reflected the real effect of the previous cell action, the conditions would be suitable for the cell to have the capacity to compare the expected effect of its previous action on the environment with the real effect that it has had.

4. The cell as a unit (as an autonomous pH field) must originate directly from the activity of the proteins that form its soma

In the cell model proposed by Cordón, in the brief cellular phase of each pulsation, all the proteins of the soma would cease their action simultaneously and, as a result, two instantaneous processes would be established:

1) the above-mentioned process of the cell action, in which the faster permeabilization of the membrane would let in environmental water, which would attract nutrient molecules through the renewal of the osmotic gradient of residual metabolites established during the long protein stage, and

2) the process of the cell unit (experience), which would be organized in the cell membrane, isolated from the cellular environment.

The physical nature of the cell unit (experience)

Schematic representation of the metabolic activity of proteins

If the efferent membrane proteins and the afferent membrane proteins, which would have maintained their corresponding H+ fields throughout the protein stage, ceased their activity instantly, in the water crystal of their phospholipids the two fields of afferent and efferent H+ would become free, and before disappearing in the general electrical environment, they would form a single field; although this was the result of the activity of proteins, it would be an independent effect of them. In accordance with the theory of integrative units, in the moment in which this field of H+ emerges (unique in nature because of the way in which it is established), and before it is merged into the general inorganic electrical-physical environment, it becomes an agent: the cell unit.

Cordón attributes two complementary properties to this ephemeral field of the cell unit (experience): the capacity to perceive the state of its environment and, according to this perception, to try out a new action.

a) The capacity of awareness: the ability to directly perceive the state of its environment. If the field of cellular experience resulted from the contrast between the real and the expected effect of the cellular action, it would be conceivable that it perceived whether this contrast was more or less favourable (i.e. whether this contrast helped to stabilize, more or less fleetingly, the field of hydrogen ions of which it consisted), and through this perception it appreciated the variations in its environment from one pulsation to the next.

b) The capacity of freedom: the capacity to decide the intensity of the next action. In other words, the ability to try out, according to the perception, the coordination of its force vectors that opposed the greatest resistance to its disappearance as an electrical field in the general hydric environment. This variation would be the test that the cell would apply to correct its previous action on the environment, ensuring that the new action had the best effect possible.

The local variations of the force vectors caused by the self-modification of the field of H+ of the cell unit would be perceived by a third set of membrane proteins, the intercalary proteins, which by maintaining the new field of H+ would guide the intensity of the set of efferent proteins that would establish the new efferent stimulus of the following pulsation.

The emergence of the cell unit from the activity of the protein of the soma would break the causal sequence by which the variations in the environment imposed the intensity of each action on the association of proteins, and between one action and the next the unpredictable correction of the unit cell would be interspersed, trying to anticipate the changes in its new environment in order to actively use it to its benefit.

The cell, as a living being, as an integrative unit resulting from the activity of its somatic proteins in each pulsation, would have the capacity to perceive the favourable or detrimental effect of its previous action on its environment and to try to correct its next action accordingly. This correction would seek the stablest possible environment for its somatic proteins.

The cellular experience (a physical field of H+ established by numerous proteins, but very tenuous) would guide its somatic proteins without perceiving their existence (because it is of a qualitatively different physical nature), and the proteins of the cell's soma would take the local changes of the cellular experience as a guide for their action, without perceiving the cell in its entirety (also because of their different physical nature), even though the cell emerged from their joint actions.

Thus, for Faustino Cordón, from the moment when a higher integrative unit emerges in phylogeny, perceiving a qualitatively new physical environment, it emerges and disappears through pulsations in an alternating interplay with the lower units that form its soma. In each pulsation, when the lower somatic units are active, the higher unit does not exist, and when the lower units cease their activity (as a direct effect of this cessation), the higher unit emerges as a unitary and ephemeral physical field (experience), which perceives and governs the changes in an environment that is consistent with it.

Schematic representation of the active movement of charges of a protein of the primordial cell

According to Cordón, the fact that each integrative unit emerges in each pulsation from the coordinated actions of its lower units means that it results from the ephemeral alterations that they cause in its environment as an effect of these actions. However, it is independent of the agents that produce it, which gives it its character of a unitary physical field that, in the moment in which it exists, tends to try to self-correct itself according to whether it has a greater or lesser consistency with the state of its environment.

Cordón considered that all strict units (all physical fields with experience) perceive the variations in their environment (capacity of awareness) and, in accordance with the perception, cause the self-correction of their lines of force, seeking to increase their fleeting stability (capacity of freedom). The correction of the force vectors of the unit's physical field -independent from the somatic units that produce it- starts to guide the intensity with which its somatic units act in the next pulsation.

From the time when a living being is born and throughout its life, in each pulsation in the instantaneous emergence of its unit (experience), it becomes an ephemeral link in the chain of the ontogenic process because, before disappearing, it will guide the associative activity of the somatic units in the next pulsation. This pulsation will in turn culminate in the establishment of a new unit, as the next link in this process, until it dies.

The achievements and limits of experimental biology and the theory of integrative level units.