Fig. 1

Id genes and znf238 expression in the brain of adult zebrafish. Id1, id2a, id2b, id3, id4 and znf238 in situ hybridization on transverse sections through the olfactory bulb/telencephalon junction (A1-F1), the telencephalon (A2-F2), the anterior (A3-F3) and posterior part (A4-F4) of the preoptic area, the anterior (A5-F5), the mediobasal (A6-F6) and the caudal (A7-F7) hypothalamus and through the medulla oblongata (A8-F8). A1 to F4: id1-id4 and znf238 expression in the anterior part of the brain, from the olfactory bulb/telencephalon junction to the end of the preoptic area. id1 as well as id3 is expressed along the brain ventricle. However, id3 is mainly detected in the subpallium. In contrast, id2a and id4 are more widely expressed and also found in the brain parenchyma. Id2b transcripts are hardly detected. znf238 is strongly expressed in the pallium, but the ventricular layer does not appear to be stained. A5 to F8: id1-id4 expression in the posterior part of the brain, from the hypothalamus to the medulla oblongata. Id1 staining is detected along the brain ventricles notably at the level of the hypothalamus and optic tectum. In contrast id2a, id3 and id4 transcripts are widely expressed in ventricular and periventricular layers of the neurogenic regions and also in the brain parenchyma. Their expression appears more or less ubiquitous. Similarly to the anterior part of the brain, id2b transcripts are hardly detectable. znf238 is strongly expressed in the valvula of the cerebellum and the cerebellum, and shows weak expression in the hypothalamus. Red dots in the zebrafish section schemes correspond to proliferative areas, which are indicated based on PCNA expression. Bars: 200 µm (A1 to F4); 280 µm (A8 to F8); 300 µm (A5 to F7).