Weightlessness as a Prerequisite for the Implementation of Biological Life Support System

Meleshko, G.!., Yeo Ya. Shepelev: Weightlessness as a Prerequisite for the 1mplementation of Biological Life Suppon System. Acta vet. Bmo 1996,65: 43-50. The implementation of human Biological Life Support System (BLSS) in the conditions of weightlessness requires a broader, ecological approach to the analysis of manifestations of weightlessness in living systems as compared to the traditional morphophysiological approach common for gravitational biology. For a stable functioning of BLSS, as an ecological system the most decisive are superorganism levels of biological organization from population to ecosystem. On these levels, the weightlessness effects may manifest themselves even if no primary biological effects on the organism level are noted. In this paper, possible weightlessness effects on living systems are discussed as well as the consequences of these effects. On different levels of organization of the living matter, from a cell to an ecosystem, weightlessness can exert different effects and these may come to the fore by different mechanisms. Ontogeny, ecology, unicellular organisms, quail, gravitational biology, population, biocenosis Modem gravitational biology directed mostly at the study of separate organisms and their subordinate levels (cellular and subcellular) gives no answer to the question of possible existence under the conditions of weightlessness of whole ecological systems where the levels above that of organism are decisive, i. e. the popUlation, biocenotic, and ecosystem levels. This inspired us to consider again, if only theoretically, the general problem of biological or other significance of weightlessness, of its possible influence mechanisms and points of impingement on different hierarchic levels of living systems. At the present stage it is important to state that the notion of the biological significance of weightlessness is essentially ambiguous. At various levels of biological organization, from the single organism to the ecosystem, weightlessness can make itself felt in different ways, and its effects can be carried out by qualitatively different mechanisms. The ideas generated by this analysis are schematically presented in Fig. 1. The first way a direct, primary influence of weightlessness on elementary biological processes, such as metabolism, development, growth, proliferation at the cell and unicellular organisms levels has not received a convincing confirmation, in spite of many-years efforts in this field. The conclusion about the absence of any specific effect of weightlessness on these main manifestations of life becomes more and more obvious. The very possibility of such an effect has no theoretical grounds yet (P a r f yon 0 v 1988). The second way of influence is not immediate, but performed through the change of gravitationally dependent physiological functions of an organism where they can manifest themselves. Here we mean the change of such functions as gravireception and the spatial orientation, haemodynamics, motor function and the connected with it processes of water-salt exchange of the body. The majority of information in this field have been received by vast research of long-duration space flights of man which have shown not only the facts of weightlessness influence, but also the mechanisms of their origin, carried out through the gravitationally dependent physiological functions. Thus, the widely known facts of weightlessness influence on the level of an adult organism do not present its primary effects, but