P1.10 Jan. 4 Developmental plasticity and heterochronic shifts induced by hypoxic conditions during early embryogenesis of zebrafish, Danio rerio SCHMIDT, K.U.; STARCK, J.M.*; Univ. Munich, Germany email@example.com
During the phylotypic stage vertebrate embryos pass through a period of morphological similarity. In zebrafish, Danio rerio, multiple correlations among characters stabilize morphology during the phylotypic stage, but a low degree of phenotypic variability is maintained (coefficient of variation ca. 4 %). However, the experimental change of temperature and salinity did not evoke a plastic reaction during this time period. Here, we studied early development of zebrafish under normoxic (100% oxygen saturation at 27°C; 8.32 mg O2 l-1; N=100), moderate hypoxia (15% oxygen saturation at 27°C; 1.66 mg O2 l-1; N=50) and severe hypoxia (10% oxygen saturation at 27°C; 0.83 mg O2 l-1; N=100). The maximum diameter of the eye, the length of the embryo, the size of somites, the inclination of somites, the size of the otic vesicle, distance between the eye and the otic vesicle, and the maximum diameter of the yolk sac of individual embryos were measured at 15, 18, 21, and 23 hours post fertilization. Compared to normoxic conditions, embryos raised in severe hypoxia grew significantly slower, but no difference was detected when they were raised in moderate hypoxia. Under normoxic condition, the onset of eye development was during the 5-somite stage, under severe hypoxic conditions the onset was delayed and shifted to the 8-somite stage. Thus, the onset of the development of the eye is clearly retarded under severe hypoxic conditions resulting in a changed sequence of organ formation.