Nucleotide polymorphisms upstream of the X-chromosome opsin gene array tune L:M cone ratio

Gunther, Karen L.; Neitz, Jay; Neitz, Maureen

doi:10.1017/s0952523808080280

Cited by 13 publications

(12 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the human retina, the expression of LWS cones exceeds that of MWS cones, and it has been suggested that opsin gene regulatory sequence variation, opsin gene proximity to the LCR, and the three-dimensional chromatin structure of the LWS / MWS locus may explain these differences [42,105-107]. As in the human LWS / MWS array, zebrafish RH2 opsin gene expression is also dependent on an LCR.…”

Section: Resultsmentioning

confidence: 99%

Genomic organization of duplicated short wave-sensitive and long wave-sensitive opsin genes in the green swordtail, Xiphophorus helleri

et al. 2010

View full text Add to dashboard Cite

BackgroundLong wave-sensitive (LWS) opsin genes have undergone multiple lineage-specific duplication events throughout the evolution of teleost fishes. LWS repertoire expansions in live-bearing fishes (family Poeciliidae) have equipped multiple species in this family with up to four LWS genes. Given that color vision, especially attraction to orange male coloration, is important to mate choice within poeciliids, LWS opsins have been proposed as candidate genes driving sexual selection in this family. To date the genomic organization of these genes has not been described in the family Poeciliidae, and little is known about the mechanisms regulating the expression of LWS opsins in any teleost.ResultsTwo BAC clones containing the complete genomic repertoire of LWS opsin genes in the green swordtail fish, Xiphophorus helleri, were identified and sequenced. Three of the four LWS loci identified here were linked in a tandem array downstream of two tightly linked short wave-sensitive 2 (SWS2) opsin genes. The fourth LWS opsin gene, containing only a single intron, was not linked to the other three and is the product of a retrotransposition event. Genomic and phylogenetic results demonstrate that the LWS genes described here share a common evolutionary origin with those previously characterized in other poeciliids. Using qualitative RT-PCR and MSP we showed that each of the LWS and SWS2 opsins, as well as three other cone opsin genes and a single rod opsin gene, were expressed in the eyes of adult female and male X. helleri, contributing to six separate classes of adult retinal cone and rod cells with average λmax values of 365 nm, 405 nm, 459 nm, 499 nm, 534 nm and 568 nm. Comparative genomic analysis identified two candidate teleost opsin regulatory regions containing putative CRX binding sites and hormone response elements in upstream sequences of LWS gene regions of seven teleost species, including X. helleri.ConclusionsWe report the first complete genomic description of LWS and SWS2 genes in poeciliids. These data will serve as a reference for future work seeking to understand the relationship between LWS opsin genomic organization, gene expression, gene family evolution, sexual selection and speciation in this fish family.

show abstract

Section: Resultsmentioning

confidence: 99%

Genomic organization of duplicated short wave-sensitive and long wave-sensitive opsin genes in the green swordtail, Xiphophorus helleri

et al. 2010

View full text Add to dashboard Cite

show abstract

“…There is evidence that chromatin remodeling is an important component of L versus M cone differentiation (Knoblauch et al, 2006;Neitz et al, 2006;McMahon et al, 2008;Gunther et al, 2008). We propose that during gestation both L and M genes are active in each cone and the cell cycles randomly between transcription of either L or M opsin.…”

Section: Discussionmentioning

confidence: 99%

Topography of the long- to middle-wavelength sensitive cone ratio in the human retina assessed with a wide-field color multifocal electroretinogram

et al. 2008

Self Cite

View full text Add to dashboard Cite

The topographical distribution of relative sensitivity to red and green lights across the retina was assayed using a custom-made wide-field color multifocal electroretinogram apparatus. There were increases in the relative sensitivity to red compared to green light in the periphery that correlate with observed increases in the relative amount of long (L) compared to middle (M) wavelength sensitive opsin mRNA. These results provide electrophysiological evidence that there is a dramatic increase in the ratio of L to M cones in the far periphery of the human retina. The central to far peripheral homogeneity in cone proportions has implications for understanding the developmental mechanisms that determine the identity of a cone as L or M and for understanding the circuitry for color vision in the peripheral retina.

show abstract

“…This explains the slight clumpiness that has been observed for the human L/M cone mosaic (Hofer, Carroll, Neitz, Neitz & Williams, 2005). Genetic changes in non-coding DNA in the region of the opsin genes are expected to influence how prone the DNA is to silencing and polymorphisms upstream of the opsin gene array have been found to be associated with individual differences in L/M cone ratio (Gunther, Neitz & Neitz, 2008, Stamatoyannopoulos, Thurman, Noble, Kutyavin, Shafer, Dorschner & Deeb, 2005). DNA is packaged as loops of chromatin in cells, and the most likely explanation for only two of the X-chromosome opsin genes being expressed is that the loop structures inhibit access of the LCR to opsin genes that are downstream of the first two genes in the array.…”

Section: Genes and The Cone Photoreceptor Mosaicmentioning

confidence: 99%

The genetics of normal and defective color vision

2011

Self Cite

View full text Add to dashboard Cite

The contributions of genetics research to the science of normal and defective color vision over the previous few decades are reviewed emphasizing the developments in the 25 years since the last anniversary issue of Vision Research. Understanding of the biology underlying color vision has been vaulted forward through the application of the tools of molecular genetics. For all their complexity, the biological processes responsible for color vision are more accessible than for many other neural systems. This is partly because of the wealth of genetic variations that affect color perception, both within and across species, and because components of the color vision system lend themselves to genetic manipulation. Mutations and rearrangements in the genes encoding the long, middle, and short wavelength sensitive cone pigments are responsible for color vision deficiencies and mutations have been identified that affect the number of cone types, the absorption spectrum of the pigments, the functionality and viability of the cones, and the topography of the cone mosaic. The addition of an opsin gene, as occurred in the evolution of primate color vision, and has been done in experimental animals can produce expanded color vision capacities and this has provided insight into the underlying neural circuitry.

show abstract

Nucleotide polymorphisms upstream of the X-chromosome opsin gene array tune L:M cone ratio

Cited by 13 publications

References 17 publications

Genomic organization of duplicated short wave-sensitive and long wave-sensitive opsin genes in the green swordtail, Xiphophorus helleri

Genomic organization of duplicated short wave-sensitive and long wave-sensitive opsin genes in the green swordtail, Xiphophorus helleri

Topography of the long- to middle-wavelength sensitive cone ratio in the human retina assessed with a wide-field color multifocal electroretinogram

The genetics of normal and defective color vision

Contact Info

Product

Resources

About