An opsin gene that is expressed only in the R7 photoreceptor cell of Drosophila.

Fryxell, Karl J.; Meyerowitz, Elliot M.

doi:10.1002/j.1460-2075.1987.tb04774.x

Cited by 101 publications

(39 citation statements)

References 55 publications

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“…Reconstitution of Drosophila R7-specific opsin expression patterns using Rh3-1acZ and Rh4-1acZ fusions RNA blot analysis has previously shown that in the adult, Rh4 is expressed exclusively in R7 photoreceptor cells and Rh3 is expressed predominantly in R7 cells (Fryxell and Meyerowitz 1987;Montell et al 1987;Zuker et al 1987}. Rh3 transcripts were also detected at lower abundance in sevenless (sevJ heads, which lack all R7 photoreceptors, and at trace levels in adult body tissues.…”

Section: Resultsmentioning

confidence: 99%

Analysis of cis-acting requirements of the Rh3 and Rh4 genes reveals a bipartite organization to rhodopsin promoters in Drosophila melanogaster.

Fortini

Rubin²

1990

Genes Dev.

218

162

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The rhodopsin genes of Drosophila melanogaster are expressed in nonoverlapping subsets of photoreceptor cells within the insect visual system. Two of these genes, Rh3 and Rh4, are known to display complementary expression patterns in the UV-sensitive R7 photoreceptor cell population of the compound eye. In addition, we find that Rh3 is expressed in a small group of paired R7 and R8 photoreceptor cells at the dorsal eye margin that are apparently specialized for the detection of polarized light. In this paper we present a detailed characterization of the cis-acting requirements of both Rh3 and Rh4. Promoter deletion series demonstrate that small regulatory regions (<300 bp) of both R7 opsin genes contain DNA sequences sufficient to generate their respective expression patterns. Individual cis-acting elements were further identified by oligonucleotidedirected mutagenesis guided by interspecific sequence comparisons. Our results suggest that the Drosophila rhodopsin genes share a simple bipartite promoter structure, whereby the proximal region constitutes a functionally equivalent promoter "core" and the distal region determines cell-type specificity. The expression patterns of several hybrid rhodopsin promoters, in which all or part of the putative core regions have been replaced with the analogous regions of different rhodopsin promoters, provide additional evidence in support of this model.

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Section: Resultsmentioning

confidence: 99%

Analysis of cis-acting requirements of the Rh3 and Rh4 genes reveals a bipartite organization to rhodopsin promoters in Drosophila melanogaster.

Fortini

Rubin²

1990

Genes Dev.

218

162

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“…The minor opsins expressed in the central R7 and R8 photoreceptor cells are coordinately expressed in nonoverlapping subsets of cells. Rh3 and Rh4 are ultraviolet-absorbing visual pigments expressed in ∼30 and 70% of the R7 cells respectively in a seemingly randomly pattern of distribution [42][43][44][45]. As with the R7 cells, the same relative proportions of R8 cells, 30 and 70%, express the blue (Rh5) and green (Rh6) absorbing pigments, respectively [46][47][48].…”

Section: Diversity Of Drosophila Rhodopsinsmentioning

confidence: 99%

Phototransduction and retinal degeneration in Drosophila

Wang

Montell

2007

Pflugers Arch - Eur J Physiol

258

303

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Drosophila visual transduction is the fastest known G-protein-coupled signaling cascade and has therefore served as a genetically tractable animal model for characterizing rapid responses to sensory stimulation. Mutations in over 30 genes have been identified, which affect activation, adaptation, or termination of the photoresponse. Based on analyses of these genes, a model for phototransduction has emerged, which involves phosphoinoside signaling and culminates with opening of the TRP and TRPL cation channels. Many of the proteins that function in phototransduction are coupled to the PDZ containing scaffold protein INAD and form a supramolecular signaling complex, the signalplex. Arrestin, TRPL, and Gα q undergo dynamic light-dependent trafficking, and these movements function in long-term adaptation. Other proteins play important roles either in the formation or maturation of rhodopsin, or in regeneration of phosphatidylinositol 4,5-bisphosphate (PIP 2 ), which is required for the photoresponse. Mutation of nearly any gene that functions in the photoresponse results in retinal degeneration. The underlying bases of photoreceptor cell death are diverse and involve mechanisms such as excessive endocytosis of rhodopsin due to stable rhodopsin/arrestin complexes and abnormally low or high levels of Ca 2+ . Drosophila visual transduction appears to have particular relevance to the cascade in the intrinsically photosensitive retinal ganglion cells in mammals, as the photoresponse in these latter cells appears to operate through a remarkably similar mechanism.

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“…To determine whether the choice of axon target of a svp mutant R1/R6 is appropriately correlated with the rhodopsin it expresses, we used Rh-lacZ transgene reporter constructs that reflect normal rhodopsin expression patterns (Papatsenko et al, 2001); whereas rhodopsin proteins are restricted to the retina, ␤-galactosidase expression is detectable in the axon, allowing us to score target selection and Rh-lacZ expression simultaneously. In wild type, 30% of R7s express Rh3 and 70% express Rh4, while 30% of R8s express Rh5 and 70% express Rh6 Montell et al, 1987;Fryxell and Meyerowitz, 1987;Fortini and Rubin, 1990;Chou et al, 1996;Papatsenko et al, 1997;Huber et al, 1997;Chou et al, 1999). We found that 67% (94/141) of svp mutant R1/R6s that target the R8 layer expressed Rh6-lacZ and 47% (30/64) expressed Rh5-lacZ (Fig.…”

Section: Research Articlementioning

confidence: 99%

Loss ofseven-upfromDrosophilaR1/R6 photoreceptors reveals a stochastic fate choice that is normally biased by Notch

et al. 2008

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Recent evidence suggests that stochasticism is important for generating cell type diversity. We have identified a novel stochastic fate choice as part of the mechanism by which Delta/Notch (Dl/N) signaling specifies R7 fate in the Drosophila eye. The equivalence of R1/R6/R7 precursors is normally broken by the activation of N, which specifies the R7 fate. The orphan nuclear hormone receptor Seven-up (Svp) is necessary and sufficient to direct R1/R6/R7 precursors to adopt the R1/R6 fate. A simple model, therefore, is that N represses Svp, which otherwise prevents adoption of the R7 fate. However, we have found that R1/R6s lacking svp stochastically adopt either the R7 or the R8 fate with equal likelihood. We show that N specifies the R7 fate by a novel branched pathway: N represses Svp expression, thereby exposing an underlying stochastic choice between the R7 and R8 fates, and then tips this choice towards the R7 fate.

show abstract

An opsin gene that is expressed only in the R7 photoreceptor cell of Drosophila.

Cited by 101 publications

References 55 publications

Analysis of cis-acting requirements of the Rh3 and Rh4 genes reveals a bipartite organization to rhodopsin promoters in Drosophila melanogaster.

Analysis of cis-acting requirements of the Rh3 and Rh4 genes reveals a bipartite organization to rhodopsin promoters in Drosophila melanogaster.

Phototransduction and retinal degeneration in Drosophila

Loss ofseven-upfromDrosophilaR1/R6 photoreceptors reveals a stochastic fate choice that is normally biased by Notch

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