Table 1.

Summary of the observed RA signaling effects on neural development in amphioxus

Neural cell population		Pharmacological treatment effects
Marker	Region	t6 BMS493	t24 BMS493	t6 RA	t24 RA
GLU-/AT-ir	Anterior	0	0	+	+
GLU-/AT-ir	Middle	0	+	+	+
GLU-/AT-ir	Posterior	0	+	−	+
hu/elav	Anterior	0	0	+	+
hu/elav	Middle	0	0	+	+/0
hu/elav	Posterior	0	+	0	+
tlx	Anterior	0	0	0	0
tlx	Middle	0	0	0	0
tlx	Posterior	0	0	−	0
soxb1c	Anterior	0	0	+	+/0
soxb1c	Middle	−	0	+	+
soxb1c	Posterior	+	+	0	+
Sensory functions		Mildly impaired	Strongly impaired	Impaired	Impaired

Results were obtained from immunohistochemical and gene expression analyses of ectodermal sensory neurons (ESNs) and ESN progenitors (ESNPs) following pharmacological treatments of developing amphioxus with the retinoic acid receptor (RAR) antagonist BMS493 or all-trans retinoic acid (RA). The developmental time point (t) of the treatments, at either 6 or 24 hpf (hours post fertilization), is given together with the compound. The observed effects on the formation of selected neural cell populations and on sensory functions are indicated. Treatment outcomes for the different neural cell populations are depicted as follows: 0 = no effect, + = gain of cells, − = loss of cells. Minor effects are indicated with a “/0”

GLU-/AT-ir glutamate/acetylated tubulin immunoreactivity