Present address: Department Neuromorphology, Brain Research Institute, University and Swiss Federal Institute of Technology, Zuerich, Switzerland.
Photoreceptor morphology is severely affected in the β,β-carotene-15,15′-oxygenase (bcox) zebrafish morphant
Article first published online: 10 JAN 2005
European Journal of Neuroscience
Volume 21, Issue 1, pages 59–68, January 2005
How to Cite
Biehlmaier, O., Lampert, J. M., Lintig, J. v. and Kohler, K. (2005), Photoreceptor morphology is severely affected in the β,β-carotene-15,15′-oxygenase (bcox) zebrafish morphant. European Journal of Neuroscience, 21: 59–68. doi: 10.1111/j.1460-9568.2004.03830.x
- Issue published online: 10 JAN 2005
- Article first published online: 10 JAN 2005
- Received 5 July 2004, revised 7 October 2004, accepted 19 October 2004
- retinal pigment epithelium;
- retinoic acid;
- vitamin A
The retinoic acid molecule, a vitamin A derivative, is of key importance for eye and photoreceptor development in vertebrates. Several studies have provided evidence that the ventral part of the retina is particularly susceptible to impairment in retinoid signalling during the period of its development. In zebrafish, targeted gene knockdown of β,β-carotene-15,15′-oxygenase (bcox), the key enzyme for vitamin A formation, provokes a loss of retinoid signalling during early eye development that results in microphthalmia at larval stages. Using this model, we analysed the consequences of this for the retinal morphology of the fish larvae in structural details. Our analyses revealed that rods and cones do not express photoreceptor specific proteins (rhodopsin, peanut agglutinin, zpr1) in the peripheral retina. The photoreceptors in the central retina showed shortened outer segments, and electron dense debris in their intermembranal space. The number of phagosomes was increased, and cell death was frequently observed in the outer nuclear layer. Furthermore, the number of Müller cells was significantly reduced in the inner nuclear layer. Thus, we found that the lack of retinoid signalling strongly effects photoreceptor development in the ventral and dorsal retina. In addition, shortened outer segments and cell death of the remaining photoreceptors in the central retina indicate that there is an ongoing need for retinoid signalling for photoreceptor integrity and survival at later developmental stages.