Fullerene C60 prevents neurotoxicity induced by intrahippocampal microinjection of amyloid-beta peptide.

The dynamics of the state of hippocampal pyramidal neurons after intrahippocampal microinjections of (1) amyloid-beta25-35 (1.6 nmol/1 microl), (2) an aqueous molecule-colloidal solution of C60 (0.46 nmol/1 microl) and (3) an aqueous molecule-colloidal solution of C60 before amyloid-beta25-35 administration were analysed in rats. This model allowed us to study the role of amyloid-beta25-35 in the pathogenesis of Alzheimer's disease and to test anti-amyloid substances. Methods of fluorescent (acridine orange) and brightfield (cresyl violet and immunohistochemistry) microscopy were used. Acridine orange staining indicated changes in protein synthesis intensity due to alterations in the rRNA state of neuron ribosomes. One day after administration of amyloid-beta25-35, the intensity of protein synthesis in the population of morphologically intact cells decreased by 45%. By day 14, degeneration occurred in the majority of pyramidal cells, and amyloid-beta25-35 deposits were observed in the neuronal cytoplasm. In necrotic cells, acridine orange staining of the cytoplasm was drastically increased as a result of RNA degradation rather than due to an increase in protein synthesis. Because amyloid-beta25-35 administration provoked oxidative stress, we assumed that an aqueous molecule-colloidal solution of C60 administered before amyloid-beta25-35 prevented protein synthesis changes on day 1, while acting as an antioxidant, and by day 14 it inhibited neurodegeneration and amyloid-beta25-35 accumulation. Based on the data that an aqueous molecule-colloidal solution of C60 prevented amyloid-beta25-35 aggregation in in vitro experiments and based on our present evidence on the antitoxicity of an aqueous molecule-colloidal solution of C60, we suggest that functionalised C60 prevents/diminishes amyloid-beta25-35 aggregation in vivo as well. Thus, an aqueous molecule-colloidal solution of C60 administered at a low concentration before amyloid-beta2-35, prevented disturbances in protein synthesis, neurodegeneration and formation amyloid-beta25-35 deposits in hippocampal pyramidal neurons in vivo. This evidence gives promise that functionalised C60 can be used to develop anti-amyloid drugs combining antioxidant and anti-aggregative properties.

Effects of hydrated forms of C60 fullerene on amyloid 1-peptide fibrillization in vitro and performance of the cognitive task.

It has been shown for the first time by transmission electron microscopy that the hydrated fullerene C60 inhibited the fibrillization of amyloid-beta25-35 peptide. The fullerene affected the amyloid-beta25-35 assembly, manifesting its anti-amyloidogenic capacity. Our in vivo investigations demonstrated also that a single intracerebroventricular injection of the C60 hydrated fullerene at a dose of 7.2 nmol/ventricle significantly improved the performance of the cognitive task in control rats. The intracerebroventricular injection of the C60 hydrated fullerene (3.6 nmol/ventricle) prevented the impairment of performance of the cognitive task induced by amyloid-beta25-35 (22.5 nmol/ventricle). The results obtained may be useful in the development of therapy of Alzheimer's disease.

Gravity independence of seed-to-seed cycling in Brassica rapa.

Growth of higher plants in the microgravity environment of orbital platforms has been problematic. Plants typically developed more slowly in space and often failed at the reproductive phase. Short-duration experiments on the Space Shuttle showed that early stages in the reproductive process could occur normally in microgravity, so we sought a long-duration opportunity to test gravity's role throughout the complete life cycle. During a 122-d opportunity on the Mir space station, full life cycles were completed in microgravity with Brassica rapa L. in a series of three experiments in the Svet greenhouse. Plant material was preserved in space by chemical fixation, freezing, and drying, and then compared to material preserved in the same way during a high-fidelity ground control. At sampling times 13 d after planting, plants on Mir were the same size and had the same number of flower buds as ground control plants. Following hand-pollination of the flowers by the astronaut, siliques formed. In microgravity, siliques ripened basipetally and contained smaller seeds with less than 20% of the cotyledon cells found in the seeds harvested from the ground control. Cytochemical localization of storage reserves in the mature embryos showed that starch was retained in the spaceflight material, whereas protein and lipid were the primary storage reserves in the ground control seeds. While these successful seed-to-seed cycles show that gravity is not absolutely required for any step in the plant life cycle, seed quality in Brassica is compromised by development in microgravity.

Microgravity effects on water supply and substrate properties in porous matrix root support systems.

The control of water content and water movement in granular substrate-based plant root systems in microgravity is a complex problem. Improper water and oxygen delivery to plant roots has delayed studies of the effects of microgravity on plant development and the use of plants in physical and mental life support systems. Our international effort (USA, Russia and Bulgaria) has upgraded the plant growth facilities on the Mir Orbital Station (OS) and used them to study the full life cycle of plants. The Bulgarian-Russian-developed Svet Space Greenhouse (SG) system was upgraded on the Mir OS in 1996. The US developed Gas Exchange Measurement System (GEMS) greatly extends the range of environmental parameters monitored. The Svet-GEMS complex was used to grow a fully developed wheat crop during 1996. The growth rate and development of these plants compared well with earth grown plants indicating that the root zone water and oxygen stresses that have limited plant development in previous long-duration experiments have been overcome. However, management of the root environment during this experiment involved several significant changes in control settings as the relationship between the water delivery system, water status sensors, and the substrate changed during the growth cycles.

Six-month space greenhouse experiments--a step to creation of future biological life support systems.

SVET Space Greenhouse (SG)--the first automated facility for growing of higher plants in microgravity was designed in the eighty years to be used for the future BLSS. The first successful experiment with vegetables was carried out in 1990 on the MIR Space Station (SS). The experiments in SVET SG were resumed in 1995, when an American Gas Exchange Measurement System (GEMS) was added. A three-month wheat experiment was carried out as part of MIR-SHUTTLE'95 program. SVET-2 SG Bulgarian equipment of a new generation with optimised characteristics was developed (financed by NASA). The new SVET-GEMS equipment was launched on board the MIR SS and a successful six-month experiments for growing up of two crops of wheat were conducted in 1996 - 97 as part of MIR-NASA-3 program. The first of these "Greenhouse" experiments (123 days) with the goal to grow wheat through a complete life cycle is described. Nearly 300 heads developed but no seeds were produced. A second crop of wheat was planted and after 42 days the plants were frozen for biochemical investigations. The main environmental parameters during the six-month experiments in SVET (substrate moisture and lighting period) are given. The results and the contribution to BLSS are discussed.

From fresh vegetables to the harvest of wheat plants grown in the "SVET" space greenhouse onboard the MIR orbital station.

NASA: Researchers report the results of experiments conducted onboard MIR in 1990, 1995, and 1996 in raising edible crops. In the 1990 experiment, radishes and Chinese cabbage were grown successfully, though the experimental plants were up to four times smaller than controls at harvest. The 1995 experiment in growing wheat through a complete life cycle was not completed. The 1996 experiment was successful in growing wheat through a complete life cycle to the seed stage. No seeds developed on any of the 279 ears harvested in that experiment. Reasons for the seedless development are explored.^ieng

Capillary movement of liquid in granular beds in microgravity.

A more complete understanding of the dynamics of capillary flow through an unsaturated porous medium would be useful for the development of an effective water and nutrient delivery system for the growth of plants in space. An experiment was conducted on the Mir Space Station that used an experimental cuvette called "Capillary Test Bed" to compare fluid migration under terrestrial laboratory conditions by positioning the cuvette such that the hydrostatic force is negated and on Mir under microgravity conditions. Differences in fluid migration in the cuvette were observed with migration being slower in microgravity compared with some ground control experiments.