title: Changes in gravitational force affect gene expression in developing organ systems at different developmental times.
abstract: BACKGROUND
  Little is known about the affect of microgravity on gene expression, particularly in vivo during embryonic development. Using transgenic zebrafish that express the gfp gene under the influence of a beta-actin promoter, we examined the affect of simulated-microgravity on GFP expression in the heart, notochord, eye, somites, and rohon beard neurons. We exposed transgenic zebrafish to simulated-microgravity for different durations at a variety of developmental times in an attempt to determine periods of susceptibility for the different developing organ systems.
  
  
  RESULTS
  The developing heart had a period of maximum susceptibility between 32 and 56 hours after fertilization when there was an approximately 30% increase in gene expression. The notochord, eye, somites, and rohon beard neurons all showed periods of susceptibility occurring between 24 and 72 hours after fertilization. In addition, the notochord showed a second period of susceptibility between 8 and 32 hours after fertilization. Interestingly, all organs appeared to be recovering by 80 hours after fertilization despite continued exposure to simulated-microgravity.
  
  
  CONCLUSIONS
  These results support the idea that exposure to microgravity can cause changes in gene expression in a variety of developing organ systems in live embryos and that there are periods of maximum susceptibility to the effects.
authors.affiliation: Department of Neuroscience and Cell Biology, Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, NJ 08854, USA. shimadna@umdnj.edu
authors.forename: Naoko
authors.initials: N
authors.lastname: Shimada
authors.forename: Gbolabo
authors.initials: G
authors.lastname: Sokunbi
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Moorman
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D047108:Embryonic Development / Q000235:genetics*; D005123:Eye / Q000737:chemistry / Q000196:embryology; D005260:Female; D018507:Gene Expression Regulation, Developmental; D049452:Green Fluorescent Proteins / Q000032:analysis; D006321:Heart / Q000196:embryology; D008297:Male; D008856:Microscopy, Fluorescence; D009206:Myocardium / Q000737:chemistry; D009474:Neurons / Q000737:chemistry; D009672:Notochord / Q000737:chemistry / Q000196:embryology; D038081:Organogenesis / Q000235:genetics*; D019170:Somites / Q000737:chemistry; D013997:Time Factors; D014893:Weightlessness; D015027:Zebrafish / Q000196:embryology / Q000235:genetics; D029961:Zebrafish Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology
chemical_list: D029961:Zebrafish Proteins; D049452:Green Fluorescent Proteins