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Oxygen-dependent gene expression in microgravity

The bio-transport research under simulated microgravity conditions, such as those that would apply during a long-duration spaceflight, has the potential to improve understanding of the oxygen transport process, which becomes more complex as the arterial wall structure, e.g. endothelial cells and its biochemical compositions are altered. Earlier reports have documented physiological changes such as reduction in red blood cell (RBC) count, reduced pulsatile blood ejection rate from the heart, changes in blood volume and distribution within the components of the cardiovascular systems, and bone loss as the duration of spaceflight increases. These changes are adaptive processes, which were formerly attributed to reduced levels of metabolic activities and less demand for oxygen by the astronauts during long-duration spaceflights. Evaluation of the effect of simulated microgravity on altered demand for oxygen and metabolic activities has been limited. Even for terrestrial gravity (~1 g) condition, few data are available for oxygen transport in cells in conjunction with microcirculation. Cellular mechanics and oxygen-sensitive gene expression under simulated microgravity have been investigated and correlated to the patho-physiological changes that occur at the cellular and molecular (DNA, RNA, and Protein) level.

In-Vitro Cell Culture Study:
i) DNA Microarray study: This study uses the rotating wall vessel bioreactor (RWV, Fig.1) designed at NASA to simulate microgravity.� Gene expression in PC12 cells in response to microgravity was analyzed by DNA microarray technology.� The microarray analysis of PC12 cells cultured for four days under simulated microgravity under standardized oxygen environment conditions revealed more than 100 genes whose expression levels were changed at least two fold compared with those from cells in the unit gravity control.� This study observed that genes involved in the oxidoreductase activity category were most significantly differentially expressed under microgravity conditions. A typical up and down regulation of genes is shown below (Fig. 2).


Fig.1 NASA developed Rotating Wall Vessel (Synthecon, TX)


Fig 2. Parts of Cluster diagram (PC12 cells): Red indicates up-regulation, while Green down, and Black no change.


ii) Protein study: Based on the microarray study, the present study is in the process of analyzing the activation of typical oxygen-dependent proteins, and to further identify the regulatory pathways and effector molecules using EMSA, Western blotting and ELISA.� The results are now being analyzed and prepared to be submitted to a related journal.

Computational Analysis of O2 Transport in RWV: The present study is to determine the appropriate suspension conditions for the microcarrier beads/cell distribution and evaluate oxygen transport and to validate the physio-chemical changes in the RWV bioreactor. The results are submitted to a related journal and now under review.

This research is partially funded by NASA-Glenn: Microgravity Division.



by Gavin D Souza last modified 2015-05-26 12:31