Role of Weightlessness on Metabolism (Actin)
Research Area: Cellular Biology
Expedition(s): 8 and 9
Principal Investigator(s): ● Johannes Boonstra, Utrecht University, Utrecht, Netherlands
RESEARCH OBJECTIVES
The Role of Weightlessness on Metabolism
(Actin) investigation studies the effect of
weightlessness on the structure and metabolism
of cellular actin microfilaments in mammalian
cells. Actin is 1 of 2 proteins involved in muscle
contraction and is found in both smooth and
striated muscles. It also serves as an important
structural molecule.
RESULTS
Preliminary experiments were performed during
two sounding rocket flights. The observed
effects of microgravity on cell morphology
suggested that the actin microfilament system
was sensitive to gravity conditions. Analysis of
the cells by fluorescence microscopy and by fluorometry revealed that the F-actin content of
the cells was increased in microgravity conditions. These preliminary observations, however,
clearly indicate that the actin microfilament system may represent a gravity-sensitive cell
component.
Ground controls samples provided predictable results. Cells showed normal actin morphology
and number of ruffles indicating that the cells survived the long period of starvation and
exposure to room temperature during the experiment. Cells that were not stimulated showed
abundant stress fibers and a pool of G-actin mainly localized around the nucleus. After
stimulation with Platelet-Derived Growth Factor (PDGF) the number of stress fibers decreased
and both F-actin and G-actin were found in circular ruffles indicating an extensive
reorganization of actin. Unfortunately no flight results were obtained due to a combination of
malfunctioning hardware and unfulfilled temperature requirements.
PUBLICATION(S)
Moes MJ. Actin dynamics in microgravity. Utrecht, Netherlands: University of Utrecht; 2012.
Moes MJ, Bijvelt JJ, Boonstra J. Actin dynamics in mouse fibroblasts in microgravity.
Microgravity Science and Technology. September 2007;19(5-6):180-183. doi:
10.1007/BF02919477.
This investigation is complete and all results are published.
Actin cytoskeleton of mouse embryo fibroblasts,
stained with Fluorescein isothiocyanate-phalloidin.
Wikipedia image.