Influence Of Simulated Microgravity Effect On Early Embryonic Bone Development Of Zebrafish

Microgravity means that the apparent gravitation of the system is much smaller than its actual gravitation.At present the microgravity environment is an unavoidable environmental irritant in space flight and work.The microgravity environment can cause serious threats such as bone loss,heart atrophy,muscle degeneration and cardiovascular disease which threaten to the health of astronauts.Bone loss caused by the microgravity environment is particularly serious,more and faster,and cannot be recovered on the ground,so studying the mechanism of microgravity environment lead to bone loss clearly is imminent.To illustrate the influence of simulated microgravity effect on the early embryonic bone development of zebrafish,this research used zebrafish as model organisms,microgravity effect as the research object,and the microgravity effect is simulated by rotary technology.The influence of simulated microgravity effect on zebrafish embryo development was evaluated by morphological observation;using semi-quantitative PCR,Real-Time PCR and whole-embryo in-situ hybridization techniques to reveal the molecular mechanism of the effect of simulated microgravity effect on the early embryonic bone development from genetic expression level.Through researching on this subject,the influence of microgravity effect on the bone development of vertebrates can be clarified and the mechanism can be revealed basically.The study could provide an assurance for astronauts in space,providing help and new ideas for correlational research in aviation medicine.Morphological observations and statistical analysis showed that simulated microgravity effect could cause the death rate to increase,hatching rate to decrease,48 hpf heart rate to risie,and 24 hpf autonomous movement frequency to increase of zebrafish embryo.It can also cause 96 hpf zebrafish deformity,such as pericardial sac edema,spinal curvature,fracture and so on.Alizarin red dyeing results implied that simulated microgravity effect could reduce the number of craniofacial bone,such as eithrum,parasphenoid,entopterygoid and operculum,and change their position.These showed that the microgravity environment inhibited the bone development andmaturity of zebrafish early embryos.Simulated microgravity effect can inhibit the expression of bone development related genes runx2 b and bmp2 b and raise the expression of oxidative stress related genes gstp1.Simulated microgravity effect could also increase the amount of ROS and MDA and increases SOD and CAT activities.These showed that the simulated microgravity effect could induce oxidative stress in early embryonic cells of zebrafish.At the same time,the simulated microgravity effect induced the endoplasmic reticulum stress in the early embryonic cells of zebrafish was found,because it promoted the expression of endoplasmic reticulum stress related genes bip and chop,and inhibited the expression of perk,it eventually led to a reduction the expression of hmox1 a who is an upstream of the runx2 b gene.All above results showed that,the simulated microgravity effect could inhibit hmox1 a gene expression by inducing oxidative stress and endoplasmic reticulum in the early embryo of zebrafish,then,it inhibited the expression of the runx2 b gene,which ultimately affected the development of bone in the early embryo of zebrafish.