RESUMO
Many maternal factors in the oocyte persist in the embryo. They are required to initiate zygotic transcription but also function beyond this stage, where they interact with zygotic gene products during embryonic development. In a four-generation screen in the zebrafish, we identified 47 maternal-effect and five paternal-effect mutants that manifest their phenotypes at the time of, or after, zygotic genome activation. We propagated a subset of 13 mutations that cause developmental arrest at the midblastula transition, defects in cell viability, embryonic morphogenesis, and establishment of the embryonic body plan. This diverse group of mutants, many not previously observed in vertebrates, demonstrates a substantial maternal contribution to the "zygotic" period of embryogenesis and a surprising degree of paternal control. These mutants provide powerful tools to dissect the maternal and paternal control of vertebrate embryogenesis.
Assuntos
Blástula/metabolismo , Embrião não Mamífero/embriologia , Regulação da Expressão Gênica no Desenvolvimento/genética , Mutação/genética , Peixe-Zebra/embriologia , Peixe-Zebra/genética , Animais , Blástula/citologia , Padronização Corporal/genética , Diferenciação Celular/genética , Linhagem da Célula/genética , Sobrevivência Celular/genética , Embrião não Mamífero/citologia , Feminino , Masculino , Fenótipo , Diferenciação Sexual/genética , Fatores Sexuais , Zigoto/citologia , Zigoto/metabolismoRESUMO
Maternal factors control development prior to the activation of the embryonic genome. In vertebrates, little is known about the molecular mechanisms by which maternal factors regulate embryonic development. To understand the processes controlled by maternal factors and identify key genes involved, we embarked on a maternal-effect mutant screen in the zebrafish. We identified 68 maternal-effect mutants. Here we describe 15 mutations in genes controlling processes prior to the midblastula transition, including egg development, blastodisc formation, embryonic polarity, initiation of cell cleavage, and cell division. These mutants exhibit phenotypes not previously observed in zygotic mutant screens. This collection of maternal-effect mutants provides the basis for a molecular genetic analysis of the maternal control of embryogenesis in vertebrates.