Mutations affecting cell fates and cellular rearrangements during gastrulation in zebrafish

TLDR

One of the major challenges of developmental biology is understanding the inductive and morphogenetic processes that shape the vertebrate embryo. We performed a large‑scale genetic screen for zygotic effects in zebrafish and identified 25 embryonic lethal mutations that disrupt cell fate specification or cellular rearrangements during gastrulation. The screen uncovered 25 lethal mutations in 14 complementation groups, of which 10 novel loci fall into three categories—dorsal mesoderm/CNS defects, ventroposterior structural defects, and disruptions of cellular rearrangements that also affect epiboly, convergence‑extension, and tail morphogenesis—highlighting genes essential for organizer function, ventral signaling, and key morphogenetic processes.

Abstract

ABSTRACT One of the major challenges of developmental biology is understanding the inductive and morphogenetic processes that shape the vertebrate embryo. In a large-scale genetic screen for zygotic effect, embryonic lethal mutations in zebrafish we have identified 25 mutations that affect specification of cell fates and/or cellular rearrangements during gastrulation. These mutations define at least 14 complementation groups, four of which correspond to previously identified genes. Phenotypic analysis of the ten novel loci revealed three groups of mutations causing distinct effects on cell fates in the gastrula. One group comprises mutations that lead to deficiencies in dorsal mesodermal fates and affect central nervous system patterning. Mutations from the second group affect formation of ventroposterior embryonic structures. We suggest that mutations in these two groups identify genes necessary for the formation, maintenance or function of the dorsal organizer and the ventral signaling pathway, respectively. Mutations in the third group affect primarily cellular rearrangements during gastrulation and have complex effects on cell fates in the embryo. This group, and to some extent mutations from the first two groups, affect the major morphogenetic processes, epiboly, convergence and extension, and tail morphogenesis. These mutations provide an approach to understanding the genetic control of gastrulation in vertebrates.