gravitational biology
Fish in space © stock.adobe.com/au/cosmicvue
A study in gravitational biology Life in a reduced-gravity environment can have lasting problems on the body, with astronauts undergoing a significant drop in bone mineral density during space missions. Unfortunately, the precise molecular mechanisms responsible for such changes in bone structure are not yet clear.
S
osteoclasts (cells that break down bone tissue).
Working from the Tsukuba Space Center
The results were published in the journal Scientific
in Japan, the team used four different double
Reports.
medaka transgenic lines focusing on upregulation
eeking to understand these molecular
The researchers’ imaging of osteoblasts showed
of fluorescent signals of osteoblasts and osteoclasts,
mechanisms, researchers from Tokyo Institute
the intensity of osterix- and osteocalcin-DsRed in
and also studied changes in the gene expression in
of Technology sent tiny Japanese rice fish —
pharyngeal bones to increase one day after launch.
the transgenic fish by transcriptome analysis. They
also known as medaka — to the International
This increased effect continued for eight days for
observed increases in both osteoblast and osteoclast
Space Station (ISS), where they were exposed to
osterix and five days for osteocalcin. In the case
specific promoter-driven GFP and DsRed signals one
microgravity. Performing real-time imaging on
of osteoclasts, the fluorescent signals observed
day after launch, which continued for up to eight days.
the fish, the researchers witnessed the emission
from TRAP-GFP and MMP9-DsRed increased
“HiSeq from pharyngeal bones of juvenile
of fluorescent signals derived from the fishes’
significantly on the fourth and sixth days after
fish at day 2 after launch showed upregulation of
osteoblasts (cells that synthesise bone) and
launch.
2 osteoblast- and 3 osteoclast-related genes,” the researchers wrote. Transcription of the ‘nucleus’ was enhanced based on whole body gene ontology analysis of RNA-Seq, with the researchers observing transcription-regulators to be more upregulated at day 2 compared with during day 6. Finally, the team identified five genes that were all upregulated in the whole body on days 2 and 6, and in the pharyngeal bone on day 2. The study serves as a major step towards uncovering the mechanisms governing changes in bone structure immediately after the onset of microgravity, when bone loss is triggered, with the researchers stating that exposure to microgravity induced an immediate “dynamic alteration of gene expressions in osteoblasts and osteoclasts”. In their next experiment, the colleagues will clarify the role of glucocorticoid receptor (GR) on cells in Fish image courtesy of yoppy (via Flickr) under CC BY 2.0
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microgravity.
LAB+LIFE SCIENTIST - Feb/Mar 2017 | 41