HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Bahadori, R. Articles by Neuhauss, S. C. F. Search for Related Content PubMed PubMed Citation Articles by Bahadori, R. Articles by Neuhauss, S. C. F.

The Zebrafish fade out Mutant: A Novel Genetic Model for Hermansky–Pudlak Syndrome

¹From the Swiss Federal Institute of Technology (ETH), Department of Biology, and Brain Research Institute, and the ³Institute of Zoology, University of Zurich, Zurich, Switzerland; and the ⁴Department of Biological Sciences, University of North Texas, Denton, Texas.

PURPOSE. To characterize retinal morphology and visual system function in the zebrafish mutant fade out (fad) and to establish the mutant as a lower vertebrate model for Hermansky–Pudlak syndrome (HPS).

METHODS. Retinal morphology of fad larvae was examined between 3 and 9 days postfertilization (dpf) by standard histology, transmission electron microscopy, and immunohistochemistry examination. Apoptotic cells were visualized by TdT-mediated dUTP nick-end labeling (TUNEL) staining. Visual system function was probed by electroretinography and behavioral assessment by optokinetic response measurements. Blood clotting was evaluated by time to occlusion testing of blood vessels as an arterial thrombosis assay. The chromosomal location of fad was determined by simple sequence-length polymorphism mapping. Genomic fragments of candidate genes were cloned by standard molecular techniques and mapped to the zebrafish genome by radiation hybrid mapping.

RESULTS. Mutant fad larvae are hypopigmented and show structural defects in the outer retina. Melanosomes of these larvae in the retinal pigment epithelium are hypopigmented, generally smaller, and progressively reduced in number compared to nonmutant larvae. Progressive microvilli protrusions into the photoreceptor cell layer are not detectable, and photoreceptor outer segments get shorter and are misaligned. Photoreceptors subsequently undergo apoptosis, with a peak of cell death at 6 dpf. Electrical responses of the retina and visual performance are severely reduced. Blood clotting is prolonged in mutant fad larvae. Genomic mapping of fad reveals distinct genomic positions of the mutant gene from known human HPS genes.

CONCLUSIONS. The fad mutant shows syndromic defects in pigmentation, outer retinal structure and function, and blood clotting. This syndrome is characteristic of Hermansky–Pudlak syndrome (HPS), making fad a novel genetic model of HPS. The gene does not cosegregate with the known human HPS genes, suggesting a novel molecular cause of HPS.

This article has been cited by other articles:

				R. J. Nuckels, A. Ng, T. Darland, and J. M. Gross The Vacuolar-ATPase Complex Regulates Retinoblast Proliferation and Survival, Photoreceptor Morphogenesis, and Pigmentation in the Zebrafish Eye Invest. Ophthalmol. Vis. Sci., February 1, 2009; 50(2): 893 - 905. [Abstract] [Full Text] [PDF]