Exposure of zebrafish larvae to 3g and 5g hyper gravity between 5-6 days post-fertilization.

The general objective of the study was to determine modulation of gene expression by environmental factors, with a special emphasis on bone formation. For this reason, the specific period of treatment was chosen between 5-6 days post-fertilization (dpf), when bone formation and calcification are taking place. Zebrafish larvae were placed at 5 dpf into a Large Diameter Centrifuge and brought to a gravitational force of 3g or 5g for 24 hours. We show that this treatment causes a clear increase of bone formation, as illustrated by cranial skeleton staining of the bone matrix by Alizarin Red, by morphometric analysis of the resulting images and by gene expression studies of selected genes. Thus, a whole genome micro-array experiment was conducted to identify genes that may be involved in the observed effect on bone formation.