[Not Available].

An overview on the effects of real and simulated microgravity on certain cell components and processes, including new information obtained recently, is presented. Attention is focused on the influence of microgravity on the cytoplasmic membrane state, transcriptome and proteome, cell wall remodeling, and Ca2+-signaling in plant cells that are not specialised to gravity perception. It is emphasized the exceptional significance of the data on the organ-specific remodeling of the transcriptome and proteome in response to space flight, that discovers new advanced approaches to implement the fundamental and applied problems of plant space biology.

[Double fertilization in flowering plants: 1898-2008].

A short review of the results of investigations in the field of plant embryology in vivo and in vitro which are directly connected with the discovery of double fertilization in flowering plants by S.G. Navashin is presented.

[The growth and differentiation of root cap columella cells and the proper root grown in the stationary conditions and under clinorotation].

The results of light- and electron-microscopic investigations of root apices of Beta vulgaris 3-day-old seedlings grown in the stationary conditions and under clinorotation are presented. It was shown that ultrastructure and topography of organelles in root cap statocytes (graviperceptive cells) and in the cells of distal elongation zone clearly reflected the different direction in their growth and differentiation in space and time in dependence on specialization and functions. Cell growth and genetically determined differentiation occur similarly to control, although certain differences in ultrastructure are evident on metabolism changes.

[Alterations of nucleolar DNA localization caused by simulated microgravity].

The functions of the nucleolus responsible for the biosynthesis of ribosomes in altered gravity are still unclear. The location of nucleolar DNA both in control and simulated microgravity has been investigated using fluorescent and immunogold cytochemistry. We have determined the redistribution of rDNA in the nucleolar components accompanied by their ultrastructure changes.

[Altered gravity affects subnucleolus localization of fibrillarin and NopA64, the most important proteins of rRNA processing].

Fibrillarin and plant nucleolin homologue NopA64 are two important nucleolar proteins involved in pre-rRNA processing. To understand better the effects of the altered gravity environment on the nucleolus functioning we have investigated the location of fibrillarin and NopA64 in nucleolar subcomponents of cress (Lepidium sativum L.) root meristematic cells grown under simulated microgravity that was compared to the control cells grown in normal conditions at I g.

[Role of cytoskeleton in gravisensitivity of a plant cell: experimental data and hypotheses].

The article highlights the hypotheses of plant gravisensing, including those where cytoskeleton is involved. Data concerning arrangement of microfilaments and microtubules in specified and non-specified to graviperception cells of higher and low plants and concepts of the role of cytoskeleton in plant gravisensing are considered.

[The growth movements of moss protonemata under clinostatic and microgravity conditions].

Populations of dark-grown protonemata of moss Ceratodon purpureus wt-4 (Germany) and wt-U (Ukraine) were rotated on clinostat or flown in space (experiment "Protonema" aboard Bion-11, December 24, 1996-January 7, 1997) to determine the effects of altered gravity on orientation of protonemata growing filaments. Protonemata had been cultivated 8 days in vertical stationary position at dark to be transported to microgravity or placed in clinostat for the period of 14 days. In the ground control, protonemata demonstrated the negatively gravitropic growth (straight upwards in a bundle of compact filaments).

[The results of the cytogenetic monitoring of the species of angiosperm plants growing in the area of the radionuclide contamination after the accident at the Chernobyl Atomic Electric Power Station].

Results of investigations of meiosis in microsporogenesis, sporads and pollen grains as well as mitosis in root meristematic cells in 94 species of angiosperms (from 28 families) growing in different ecological conditions in the zone with higher radionuclide pollution after the Ch.NPS accident are present. The low percentage (0.

[The characteristics of the structural organization of Chlorella cells cultured over 1 year under space flight conditions].

Ultrastructure of Chlorella cells grown in individual colonies for 12 months on board of the orbital station "Mir" was studied. A number of differences in submicroscopic organization of cell organelles of the experimental population was detected in comparison with the control. Besides, the spectrum of ultrastructural rearrangements of cell organelles was broader, then in our previous experiments that lasted from 4.