Abstract
We characterized an amphioxus NK-2 homeobox gene (AmphiNk2–1), a homologue of vertebrate Nkx2–1, which is involved in the development of the central nervous system and thyroid gland. At the early neurula stage of amphioxus, AmphiNk2–1 expression is first detected medially in the neural plate. By the mid-neurula stage, expression is localized ventrally in the nerve cord and also begins in the endoderm. During the late neurula stage, the ventral neural expression becomes transiently segmented posteriorly and is then down-regulated except in the cerebral vesicle at the anterior end of the central nervous system. Within the cerebral vesicle AmphiNk2–1 is expressed in a broad ventral domain, probably comprising both the floor plate and basal plate regions; this pattern is comparable to Nkx2–1 expression in the mouse diencephalon. In the anterior part of the gut, expression becomes intense in the endostyle (the right wall of the pharynx), which is the presumed homologue of the vertebrate thyroid gland. More posteriorly, there is transitory expression in the midgut and hindgut. In sum, the present results help to support homologies (1) between the amphioxus endostyle and the vertebrate thyroid gland and (2) between the amphioxus cerebral vesicle and the vertebrate diencephalic forebrain.
Similar content being viewed by others
Author information
Authors and Affiliations
Additional information
Received: 4 September 1998 / Accepted: 24 October 1998
Rights and permissions
About this article
Cite this article
Venkatesh, T., Holland, N., Holland, L. et al. Sequence and developmental expression of amphioxus AmphiNk2–1: insights into the evolutionary origin of the vertebrate thyroid gland and forebrain. Dev Gene Evol 209, 254–259 (1999). https://doi.org/10.1007/s004270050250
Issue Date:
DOI: https://doi.org/10.1007/s004270050250