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Genetic Dissection of Dual Roles for the Transcription Factor six7 in Photoreceptor Development and Patterning in Zebrafish.

Title: Genetic Dissection of Dual Roles for the Transcription Factor six7 in Photoreceptor Development and Patterning in Zebrafish.
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Name(s): Sotolongo-Lopez, Mailin, author
Alvarez-Delfin, Karen, author
Saade, Carole J, author
Vera, Daniel L, author
Fadool, James M, author
Type of Resource: text
Genre: Journal Article
Text
Date Issued: 2016-04-08
Physical Form: computer
online resource
Extent: 1 online resource
Language(s): English
Abstract/Description: The visual system of a particular species is highly adapted to convey detailed ecological and behavioral information essential for survival. The consequences of structural mutations of opsins upon spectral sensitivity and environmental adaptation have been studied in great detail, but lacking is knowledge of the potential influence of alterations in gene regulatory networks upon the diversity of cone subtypes and the variation in the ratio of rods and cones observed in numerous diurnal and nocturnal species. Exploiting photoreceptor patterning in cone-dominated zebrafish, we uncovered two independent mechanisms by which the sine oculis homeobox homolog 7 (six7) regulates photoreceptor development. In a genetic screen, we isolated the lots-of-rods-junior (ljrp23ahub) mutation that resulted in an increased number and uniform distribution of rods in otherwise normal appearing larvae. Sequence analysis, genome editing using TALENs and knockdown strategies confirm ljrp23ahub as a hypomorphic allele of six7, a teleost orthologue of six3, with known roles in forebrain patterning and expression of opsins. Based on the lack of predicted protein-coding changes and a deletion of a conserved element upstream of the transcription start site, a cis-regulatory mutation is proposed as the basis of the reduced expression of six7 in ljrp23ahub. Comparison of the phenotypes of the hypomorphic and knock-out alleles provides evidence of two independent roles in photoreceptor development. EdU and PH3 labeling show that the increase in rod number is associated with extended mitosis of photoreceptor progenitors, and TUNEL suggests that the lack of green-sensitive cones is the result of cell death of the cone precursor. These data add six7 to the small but growing list of essential genes for specification and patterning of photoreceptors in non-mammalian vertebrates, and highlight alterations in transcriptional regulation as a potential source of photoreceptor variation across species.
Identifier: FSU_pmch_27058886 (IID), 10.1371/journal.pgen.1005968 (DOI), PMC4825938 (PMCID), 27058886 (RID), 27058886 (EID), PGENETICS-D-15-02805 (PII)
Grant Number: F31 EY020106, R01 EY017753
Publication Note: This NIH-funded author manuscript originally appeared in PubMed Central at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4825938.
Subject(s): Alleles
Animals
Body Patterning
Homeodomain Proteins/genetics
Homeodomain Proteins/physiology
Photoreceptor Cells, Vertebrate/metabolism
Zebrafish/embryology
Zebrafish Proteins/genetics
Zebrafish Proteins/physiology
Persistent Link to This Record: http://purl.flvc.org/fsu/fd/FSU_pmch_27058886
Owner Institution: FSU
Is Part Of: PLoS genetics.
1553-7404
Issue: iss. 4, vol. 12

Choose the citation style.
Sotolongo-Lopez, M., Alvarez-Delfin, K., Saade, C. J., Vera, D. L., & Fadool, J. M. (2016). Genetic Dissection of Dual Roles for the Transcription Factor six7 in Photoreceptor Development and Patterning in Zebrafish. Plos Genetics. Retrieved from http://purl.flvc.org/fsu/fd/FSU_pmch_27058886