Tissue-specific expression of FoxD reporter constructs in amphioxus embryos

Yu, JK, Holland ND, Holland LZ.  2004.  Tissue-specific expression of FoxD reporter constructs in amphioxus embryos. Developmental Biology. 274:452-461.

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acid, Branchiostoma floridae, cell fate, ciona-intestinalis, Cis-regulatory sequence, construct, developmental expression, evolution, floor plate, forebrain, fox domain transcription factor, gene, nerve cord, neural crest, neural crest evolution, notochord, repetitive DNA, reporter gene, retinoic, somite, transcription factor foxd3, vertebrate origins


Cephalochordates (amphioxus), the closest living invertebrate relatives of the vertebrates, are key to understanding the evolution of developmental mechanisms during the invertebrate-to-vertebrate transition. However, a major impediment to amphioxus as a model organism for developmental biology has been the inability to introduce transgenes or other macromolecules into the embryos. Here, we report the development of a reproducible method for microinjection of amphioxus eggs. Specifically, we show that expression of a LacZ reporter construct including 6.3 kb of AmphiFoxD upstream regulatory DNA recapitulates expression of the endogenous gene in the nerve cord, somites, and notochord. We have also identified the 1.6 kb at the 5' end of this region as essential for expression in the first two of these domains and the 4.7 kb at the 3' end as sufficient for expression in the notochord. This study, which is the first report of a method for introduction of large molecules such as DNA into amphioxus embryos, opens the way for studies of gene regulation and function in amphioxus and for comparative studies with vertebrates to understand the relationship between the extensive gene duplications that occurred within the vertebrate lineage and the evolution of vertebrate innovations such as neural crest. (C) 2004 Elsevier Inc. All rights reserved.