Long clinostation influence on the ultrastructure of Funaria hygrometrica moss protonema cells

Changes in the ultrastructure of protonema cells of Funaria hygrometrica, cultivated during 20 days on a horizontal clinostat (2 rev/min), were determined by the electron microscopy method. About 20% of the cells were almost identical to those in the control, 20% were destructive cells, and in 60% ultrastructure changes were observed. The heterogeneity of the reaction demonstrated the evidence of sensitive cells on the clinostation process. Changes affected the ultrastructure of plastids, wall of the cell, and the form of the nucleus as well. Starch disappeared from chloroplasts practically completely, thylakoids swelled, granas frequently disappeared from plastids. Peroxisomes number in cells increased appreciably, width of cell walls decreased by almost half their size. Ca⁺⁺-binding sites were revealed in cytoplasma of cells. Electronocytochemical exposure of ATPases activity with the presence of Mg⁺⁺ and Ca⁺⁺ ions showed that Mg²⁺-ATPase activity localization in clinosted cells was not too different from the control, while Ca²⁺-ATPase location presented differences in plasmalemma and Ca-sites. These changes are perhaps connected with the membranes permeability breaking and affect the plant cells adaptation to the influence of hypogravitation.