Anatomy of zebrafish cerebellum and screen for mutations affecting its development

Abstract

The cerebellum is important for the integration of sensory perception and motor control, but its structure has mostly been studied in mammals. Here, we describe the cell types and neural tracts of the adult zebrafish cerebellum using molecular markers and transgenic lines. Cerebellar neurons are categorized to two major groups: GABAergic and glutamatergic neurons. The Purkinje cells, which are GABAergic neurons, express parvalbumin7, carbonic anhydrase 8, and aldolase C like (zebrin II). The glutamatergic neurons are vglut1(+) granule cells and vglut2(high) cells, which receive Purkinje cell inputs; some vglut2(high) cells are eurydendroid cells, which are equivalent to the mammalian deep cerebellar nuclei. We found olig2(+) neurons in the adult cerebellum and ascertained that at least some of them are eurydendroid cells. We identified markers for climbing and mossy afferent fibers, efferent fibers, and parallel fibers from granule cells. Furthermore, we found that the cerebellum-like structures in the optic tectum and antero-dorsal hindbrain show similar Parvalbumin7 and Vglut1 expression profiles as the cerebellum. The differentiation of GABAergic and glutamatergic neurons begins 3 days post-fertilization (dpf), and layers are first detectable 5 dpf. Using anti-Parvalbumin7 and Vglut1 antibodies to label Purkinje cells and granule cell axons, respectively, we screened for mutations affecting cerebellar neuronal development and the formation of neural tracts. Our data provide a platform for future studies of zebrafish cerebellar development.

Expression of the transcription factor Olig2 in proliferating cells in the adult zebrafish telencephalon

“…Most of the other Tg(olig2:EGFP) cells were suggested to be neurons as they express the neuronal marker HuC/D and not Sox10 (Bae et al, 2009). This is in contrast to our results in the telencephalon where we could not detect co-expression of HuC/ D and Tg(olig2:EGFP).…”

“…Precedent studies of olig2 expression in a different adult zebrafish brain region, the cerebellum, showed that only a minority of Tg(olig2:EGFP) cells co-express Sox10 (Bae et al, 2009). Most of the other Tg(olig2:EGFP) cells were suggested to be neurons as they express the neuronal marker HuC/D and not Sox10 (Bae et al, 2009).…”

Cerebellar-Dependent Learning in Larval Zebrafish

“…Because the connectivity of the cerebellum in teleost fish is similar to that in mammals (Bae et al, 2009) and some reports have suggested its involvement in learning (Gó mez et al, 2010), we hypothesized that the zebrafish cerebellum plays a similar role in our simple conditioning protocol. We found that CCe lesions delivered before conditioning prevented the acquisition of the CR, whereas memory retention and expression remained unaffected when the cerebellum was ablated after conditioning (Fig.…”

Phylogeny and expression divergence of metabotropic glutamate receptor genes in the brain of zebrafish (Danio rerio)

“…An overview of mglur expressions in larval zebrafish is shown in Table 2. We generally followed the nomenclature of the zebrafish brain atlas of larval (Mueller and Wullimann, 2005) and adult (Wullimann et al, 1996) zebrafish and followed some modifications suggested by other authors (Bae et al, 2009;Wullimann and Mueller, 2004a;Mueller et al, 2006 is located in Purkinje cells but additionally in the granule cell layer of the corpus cerebelli and in the lobus caudalis cerebelli (GCL, LCa; Fig. 4L,R-T).…”

“…Consistent with that we find prominent expression for both mglur1 paralogs in the zebrafish cerebellum. At larval stages the cerebellar mglur1a-riboprobe detects cells that resemble a Purkinje cell staining of an antibody against Parvalbumin7 (Bae et al, 2009). In contrast to Parvalbumin 7, mglur1b is additionally expressed in a subpopulation of granule cells in the dorsal and lateral part of the cerebellum.…”