Exposure to Simulated Microgravity Affects Development of the Skull in Danio rerio

Abstract

To determine how exposure to simulated microgravity (SMG) affects development of the skull, zebrafish embryos were exposed to SMG starting at one of three developmental stages: 10, 12 or 14 hours post‐fertilization. Juvenile and adult fish were analyzed after exposure to SMG using whole‐mount staining and geometric morphometrics. Fish were examined for changes in melanophore surface area and number, in addition to changes in skull morphology. Analyses reveal an overall decrease in the surface area of melanophores and an increase in melanophore number over the period of a week in experimental and control groups; with significant differences in the number of melanophores on the first day after exposure. These effects are short‐term and do not persist in adults. Gross morphological analyses of whole‐mount stained adults, however, identified buckling in several (but not all) craniofacial bones. In conclusion, exposure to SMG affects both skeletal tissues and pigmentation in the head. These results will be discussed in context of germ layer origin. This is the first study examining the long‐term effects of exposure to SMG on zebrafish and provides valuable insight into phenotypic variation.Grant Funding Source : NSERC, Canada; and CSA, Canada