Molecular and cell biological study of functions and mechanisms of vertebrate gap gene Otx1

点击翻译按钮获取中文摘要

Functions of a rostral gap gene Otx 1 in developing zebrafish embryos were studied with molecular and cell biological strategies. (1) Functional studies of mis-expressed Otx1 : Zebrafish embryos micro-injected with in vitro synthesized Otx1 RNA at their 1-cell stage showed significant gastrulation defects in dose-dependent manner, suggesting its inhibitory action on cell motility. When Otx1 RNA was injected along with GFP RNA to a single cell of 16-cell embryos, its daughter cells with GFP fluorescence formed tight aggregates often on the yolk. On the other hand, when 32-cell stage embryos were injected in their a single cell by animal pole, fluorescent cells often migrated to future forbrain-midbrain region and incorporated to normal rostral structures. Studies with caged fluorescein tracer showed cells in this region retain coherence in spite of massive cell movements during gastrulation. Otx1 construct with glucocorticoid ligand-binding domain induced cell aggregation only upon activation with dexamethasone. These results indicated Otx1 induces isotypic cell adhesion by which define future forbrain-midbrain region. (2) Screening for downstream genes and factors of Otx1 : Zebrafish library was screened for cadherin and protocadherin as most-likely candicates. It gave some clones of cadherin superfamilies. Future plans are investigated for other classes of downstream genes.