Works 2 not work not work 2 works

ordinaryenvironment(A) ²H₂O (B)

4.1. The main hypothese.

We proposed that a cell theoretically could in principle synthezise a big number of forms of [²H]labeled macromolecules with somewhat different structures and conformations, so that a cell could easily select a preferable one from al these species in a course of adaptation to ²H₂O, that is the best suitable namely for that conditions. A simple imaginary principle I am going to discuss here perhaps somewhat may explain this probable mechanism. Let us suppose, for example that there are at least two imadinary structural systems - ordinary (normal) system call it a system 1 and unordinary (adaptive) system 2 (see a Figure above). Supporse, that the environment is a homoginious substanse and compose from ordinary substance A (H₂O) (situation 1). The necessarely condition for the normal working of this model in natural H₂O environment is that system 1 works and system 2 stay in background (situation 2). Supporse, that the environment have changed for substance B (²H₂O). Then the system 2 will work, while the system 1 will stay in background (situation 2). When environment will be the natural again, the system 1 will begin the work again, while the system 2 will stay in background. Admitt, that the two systems both presented at the time being and could be regulated in such way that they may switch bitween each other during the working so that the model system does not undergoing the considerable alterations.

4.2. Phenomenon of biological adaptation to ²H₂O.

Our research has confirmed, that ability to adaptation to ²Н₂О is differed for various species of bacteria and can to be varried even in frames of one taxonomic family (Mosin O. V. et al., 1996a, 1996b).From this, it is possible to conclude, that the adaptation to ²Н₂О is determined both by taxonomic specifity of the organism, and peculiarities of the metabolism, as well as by functioning of various ways of accimilation of hydrogen (deuterium) substrates, as well as evolutionary level, which an object itself occupies. The less a level of evolutionary development of an organism, the better it therefore adapts itself to ²H₂O. For example, there are halophilic bacteria that are being the most primitive in the evolutionary plan, and therefore, they practically not requiring to carry out a special adaptation methods to grow on ²Н₂О. On the contrary, bacills (eubacteria) and methylotrophs (gram-negative bacteria) worse adapted to ²Н₂О.

At the same time for all tested cells the growth on ²H₂O was accompanied by considerable decrease of a level of biosynthesis of appropriated cellular compounds. The data obtained confirm that the adaptation to ²Н₂О is a rather phenotypical phenomenon, as the adapted cells could be returned to a normal growth and biosynthesis in protonated media after lag-phase (Mosin O. V. et al., 1993).

However, when the adaptive process goes continuously during the many generation, the population of cells can use a special genetic mechanisms for the adaptation to ²H₂O. For example, mutations of geens can be resulted in amino acid replacements in molecules of proteins, which in turn could cause a formation of a new isoenzymes, and in the special cases - even the anomal working enzymes of a newer structure type. The replacements of these compounds can ensure a development of new ways of regulation of enzymic activity, ensuring more adequate reaction to signals, causing a possible changes in speeds and specifity of metabolic processes.

Despite it, the basic reactions of metabolism of adapted cells probably do not undergo essential changes in ²Н₂О. At the same time the effect of convertibility of growth on Н₂О/²Н₂О - does not theoretically exclude an opportunity that this attribute is stably kept when cells grown on ²Н₂О, but masks when transfer the cells on deuterated medium.

However, here it is necessary to emphasize, that for realization of biological adaptation to ²H₂O the composition of growth medium plays an important role. In this case it is not excluded, that during the adaptation on the minimal medium, containing ²Н₂О there are formed the forms of bacteria, auxotrophic on a certain growth factors (for example amino acids et) and thereof bacterial growth is inhibited while grown on these media. At the same time the adaptation to ²Н₂О occurs best on complex media, the composition of which coul compensate the requirement in those growth factors.

It is possible also to assume, that the macromolecules realize the special mechanisms, which promote a stabilization of their structure in ²H₂O and the functional reorganization for best working in ²Н₂О. Thus, the distinctions in nuclear mass of hydrogen atom and deuterium can indirectly to be a reason of distinctions in synthesis of deuterated forms of DNA and proteins, which can be resulting in the structural distinctions and, hence, to functional changes of [²H]labeled macromolecules. Hawever, it is not excluded, that during incubation on ²Н₂О the enzymes do not stop the function, but changes stipulating by isotopic replacement due to the primary and secondary isotopic effects as well as by the action of ²Н₂О as solvent (density, viscosity) in comparison with Н₂О are resulted in changes of speeds and specifics of metabolic reactions.

In the case with biological adaptation to ²H₂O we should inspect the following types of adaptive mechanisms: