Spermidine, but not spermine, is essential for pigment pattern formation in zebrafish.

Polyamines are small poly-cations essential for all cellular life. The main polyamines present in metazoans are putrescine, spermidine and spermine. Their exact functions are still largely unclear; however, they are involved in a wide variety of processes affecting cell growth, proliferation, apoptosis and aging.

A dominant mutation in tyrp1A leads to melanophore death in zebrafish.

Melanin biosynthesis in vertebrates depends on the function of three enzymes of the tyrosinase family, tyrosinase (Tyr), tyrosinase-related protein 1 (Tyrp1), and dopachrome tautomerase (Dct or Tyrp2). Tyrp1 might play an additional role in the survival and proliferation of melanocytes. Here, we describe a mutation in tyrp1A, one of the two tyrp1 paralogs in zebrafish, which causes melanophore death leading to a semi-dominant phenotype.

Large-scale mapping of mutations affecting zebrafish development.

Background: Large-scale mutagenesis screens in the zebrafish employing the mutagen ENU have isolated several hundred mutant loci that represent putative developmental control genes. In order to realize the potential of such screens, systematic genetic mapping of the mutations is necessary. Here we report on a large-scale effort to map the mutations generated in mutagenesis screening at the Max Planck Institute for Developmental Biology by genome scanning with microsatellite markers.

Retinal function and morphology in two zebrafish models of oculo-renal syndromes.

We characterized visual system defects in two recessive zebrafish mutants oval and elipsa. These mutants share the syndromic phenotype of outer retinal dystrophy in conjunction with cystic renal disorder. We tested the function of the larval visual system in a behavioural assay, eliciting optokinetic eye movements by high-contrast motion stimulation while recording eye movements in parallel.

astray, a zebrafish roundabout homolog required for retinal axon guidance.

As growing retinotectal axons navigate from the eye to the tectum, they sense guidance molecules distributed along the optic pathway. Mutations in the zebrafish astray gene severely disrupt retinal axon guidance, causing anterior-posterior pathfinding defects, excessive midline crossing, and defasciculation of the retinal projection. Eye transplantation experiments show that astray function is required in the eye.

A radiation hybrid map of the zebrafish genome.

Recent large-scale mutagenesis screens have made the zebrafish the first vertebrate organism to allow a forward genetic approach to the discovery of developmental control genes. Mutations can be cloned positionally, or placed on a simple sequence length polymorphism (SSLP) map to match them with mapped candidate genes and expressed sequence tags (ESTs). To facilitate the mapping of candidate genes and to increase the density of markers available for positional cloning, we have created a radiation hybrid (RH) map of the zebrafish genome.