scholarly journals Functional Characterization and Molecular Cloning of the K+-dependent Na+/Ca2+ Exchanger in Intact Retinal Cone Photoreceptors

2006 ◽  
Vol 129 (1) ◽  
pp. 1-16 ◽  
Author(s):  
Christophe Paillart ◽  
Robert J. Winkfein ◽  
Paul P.M. Schnetkamp ◽  
Juan I. Korenbrot
Keyword(s):  
Outer Segment ◽  
Splice Variants ◽  
Functional Characterization ◽  
Cone Photoreceptors ◽  
Single Class ◽  
Rod Photoreceptors ◽  
Reverse Mode ◽  
Single Cone ◽  
Polymerase Chain ◽  
Retinal Cone

Light-dependent changes in cytoplasmic free Ca2+ are much faster in the outer segment of cone than rod photoreceptors in the vertebrate retina. In the limit, this rate is determined by the activity of an electrogenic Na+/Ca2+ exchanger located in the outer segment plasma membrane. We investigate the functional properties of the exchanger activity in intact, single cone photoreceptors isolated from striped bass retina. Exchanger function is characterized through analysis both of the electrogenic exchanger current and cytoplasmic free Ca2+ measured with optical probes. The exchanger in cones is K+ dependent and operates both in forward and reverse modes. In the reverse mode, the K+ dependence of the exchanger is described by binding to a single site with K1/2 about 3.6 mM. From the retina of the fish we cloned exchanger molecules bassNCKX1 and bassNCKX2. BassNCKX1 is a single class of molecules, homologous to exchangers previously cloned from mammalian rods. BassNCKX2 exists in four splice variants that differ from each other by small sequence differences in the single, large cytoplasmic loop characteristic of these molecules. We used RT-PCR (reverse transcriptase polymerase chain reaction) of individual cells to identify the exchanger molecule specifically expressed in bass single and twin cone photoreceptors. Each and every one of the four bassNCKX2 splice variants is expressed in both single and twin cones indistinguishably. BassNCKX1 is not expressed in cones and, by exclusion, it is likely to be an exchanger expressed in rods.

scholarly journals Optics of cone photoreceptors in the chicken ( Gallus gallus domesticus )

2015 ◽  
Vol 12 (111) ◽  
pp. 20150591 ◽  
Author(s):  
David Wilby ◽  
Matthew B. Toomey ◽  
Peter Olsson ◽  
Rikard Frederiksen ◽  
M. Carter Cornwall ◽  
...  
Keyword(s):  
Outer Segment ◽  
Sensory Modality ◽  
Digital Holographic Microscopy ◽  
Cone Photoreceptors ◽  
Oil Droplets ◽  
Oil Droplet ◽  
Integrated Optical ◽  
Single Cone ◽  
Holographic Microscopy ◽  
Electromagnetic Models

Vision is the primary sensory modality of birds, and its importance is evident in the sophistication of their visual systems. Coloured oil droplets in the cone photoreceptors represent an adaptation in the avian retina, acting as long-pass colour filters. However, we currently lack understanding of how the optical properties and morphology of component structures (e.g. oil droplet, mitochondrial ellipsoid and outer segment) of the cone photoreceptor influence the transmission of light into the outer segment and the ultimate effect they have on receptor sensitivity. In this study, we use data from microspectrophotometry, digital holographic microscopy and electron microscopy to inform electromagnetic models of avian cone photoreceptors to quantitatively investigate the integrated optical function of the cell. We find that pigmented oil droplets primarily function as spectral filters, not light collection devices, although the mitochondrial ellipsoid improves optical coupling between the inner segment and oil droplet. In contrast, unpigmented droplets found in violet-sensitive cones double sensitivity at its peak relative to other cone types. Oil droplets and ellipsoids both narrow the angular sensitivity of single cone photoreceptors, but not as strongly as those in human cones.

scholarly journals Identification and Functional Characterization of a Cold-Related Protein, BcHHP5, in Pak-Choi (Brassica rapa ssp. chinensis)

2018 ◽  
Vol 20 (1) ◽  
pp. 93
Author(s):  
Jin Wang ◽  
Feiyi Huang ◽  
Xiong You ◽  
Xilin Hou
Keyword(s):  
Brassica Rapa ◽  
Abiotic Stresses ◽  
Quantitative Polymerase Chain Reaction ◽  
Functional Characterization ◽  
Regulation Mechanism ◽  
Pak Choi ◽  
Negative Effect ◽  
Polymerase Chain ◽  
Related Proteins

In plants, heptahelical proteins (HHPs) have been shown to respond to a variety of abiotic stresses, including cold stress. Up to the present, the regulation mechanism of HHP5 under low temperature stress remains unclear. In this study, BcHHP5 was isolated from Pak-choi (Brassica rapa ssp. chinensis cv. Suzhouqing). Sequence analysis and phylogenetic analysis indicated that BcHHP5 in Pak-choi is similar to AtHHP5 in Arabidopsis thaliana. Structure analysis showed that the structure of the BcHHP5 protein is relatively stable and highly conservative. Subcellular localization indicated that BcHHP5 was localized on the cell membrane and nuclear membrane. Furthermore, real-time quantitative polymerase chain reaction (RT-qPCR) analysis showed that BcHHP5 was induced to express by cold and other abiotic stresses. In Pak-choi, BcHHP5-silenced assay, inhibiting the action of endogenous BcHHP5, indicated that BcHHP5-silenced might have a negative effect on cold tolerance, which was further confirmed. All of these results indicate that BcHHP5 might play a role in abiotic response. This work can serve as a reference for the functional analysis of other cold-related proteins from Pak-choi in the future.

Two opposite effects of ATP on the apparent sensitivity of the cGMP-gated channel of the carp retinal cone

1997 ◽  
Vol 14 (4) ◽  
pp. 609-615 ◽  
Author(s):  
Shu-Ichi Watanabe ◽  
Jing Shen
Keyword(s):  
Cone Photoreceptors ◽  
Apparent Affinity ◽  
Enhancing Effect ◽  
Cyclic Monophosphate ◽  
Maximum Current ◽  
Gated Channel ◽  
Retinal Cone ◽  
A Current

AbstractEffects of ATP on the activity of cGMP-gated channels from carp cone photoreceptors were studied. In 29% of the patches examined (N = 45), ATP (1 mM) enhanced a current evoked by cGMP (20 μM, up to about 100%), in 33%, ATP suppressed it by up to about 90%, and in the remaining 38%, ATP had no effect. ATP showed similar effects on a current evoked by 8-bromoguanosine 3′,5′-cyclic monophosphate (2 μM, enhancing in 42% of the patches, suppressing in 25%, no effect in 33%, N = 12), suggesting that the effects were not through modulation of the phosphodiesterase. Both of the effects, enhancement and suppression, were produced by a change in apparent affinity for cGMP, since (1) the maximum current evoked by cGMP of the saturating concentration (≥1 mM) was not affected, and (2) the A1/2 value decreased by approximately 45% (N = 2) or increased by approximately 25% (N = 2). A lower pH (approximately 6) facilitated the enhancing effect. ATP-γ-S (1 mM) showed a suppressing effect in 80% of the patches and no effect in 20% of the patches (N = 10). However, ATP-γ-S did not show an enhancing effect. Thus, ATP had two opposite effects through different mechanisms on the apparent sensitivity of the channel to cGMP; increasing and decreasing.

scholarly journals Ciliary neurotrophic factor (CNTF) protects retinal cone and rod photoreceptors by suppressing excessive formation of the visual pigments

2018 ◽  
Vol 293 (39) ◽  
pp. 15256-15268 ◽  
Author(s):  
Songhua Li ◽  
Kota Sato ◽  
William C. Gordon ◽  
Michael Sendtner ◽  
Nicolas G. Bazan ◽  
...  
Keyword(s):  
Neurotrophic Factor ◽  
Ciliary Neurotrophic Factor ◽  
Visual Pigments ◽  
Rod Photoreceptors ◽  
Retinal Cone

scholarly journals Author Correction: Cryptochrome 1 in Retinal Cone Photoreceptors Suggests a Novel Functional Role in Mammals

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Christine Nießner ◽  
Susanne Denzau ◽  
Erich Pascal Malkemper ◽  
Julia Christina Gross ◽  
Hynek Burda ◽  
...  
Keyword(s):  
Functional Role ◽  
Cone Photoreceptors ◽  
Cryptochrome 1 ◽  
Retinal Cone

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

PRCD is Concentrated at the Base of Photoreceptor Outer Segments and is Involved in Outer Segment Disc Formation

2019 ◽  
Author(s):  
Gilad Allon ◽  
Irit Mann ◽  
Lital Remez ◽  
Elisabeth Sehn ◽  
Leah Rizel ◽  
...  
Keyword(s):  
Retinal Degeneration ◽  
Knockout Mice ◽  
Outer Segment ◽  
Mouse Retina ◽  
Cone Photoreceptors ◽  
Photoreceptor Outer Segment ◽  
Photoreceptor Outer Segments ◽  
Outer Segments ◽  
Rod And Cone Photoreceptors ◽  
Disc Formation

Abstract Mutations of the PRCD gene are associated with rod-cone degeneration in both dogs and humans. Prcd is expressed in the mouse eye as early as embryonic day 14. In the adult mouse retina PRCD is expressed in the outer segments of both rod and cone photoreceptors. Immunoelectron microscopy revealed that PRCD is located at the outer segment rim, and that it is highly concentrated at the base of the outer segment. Prcd-knockout mice present with progressive retinal degeneration, starting at 20 weeks of age and onwards. This process is reflected by a significant and progressive reduction of both scotopic and photopic electroretinographic responses, and by thinning of the retina, and specifically of the outer nuclear layer, indicating photoreceptor loss. Electron microscopy revealed severe damage to photoreceptor outer segments, which is associated with immigration of microglia cells to the Prcd-knockout retina, and accumulation of vesicles in the inter-photoreceptor space. Phagocytosis of photoreceptor outer segment discs by the retinal pigmented epithelium is severely reduced. Our data show that Prcd-knockout mice serve as a good model for retinal degeneration caused by PRCD mutations in humans. Our findings in these mice support the involvement of PRCD in outer segment disc formation of both rod and cone photoreceptors. Furthermore, they suggest a feedback mechanism which coordinates the rate of photoreceptor outer segment disc formation, shedding and phagocytosis. This study has important implications for understanding the function of PRCD in the retina, as well as for future development of treatment modalities for PRCD-deficiency in humans.

Tissue specificity and alternative splicing of the Na+/Ca2+ exchanger isoforms NCX1, NCX2, and NCX3 in rat

1997 ◽  
Vol 272 (4) ◽  
pp. C1250-C1261 ◽  
Author(s):  
B. D. Quednau ◽  
D. A. Nicoll ◽  
K. D. Philipson
Keyword(s):  
Skeletal Muscle ◽  
Polymerase Chain Reaction ◽  
Alternative Splicing ◽  
Reverse Transcriptase ◽  
Splice Variants ◽  
Variable Region ◽  
Intracellular Loop ◽  
Chain Reaction ◽  
Splicing Isoforms ◽  
Polymerase Chain

The gene coding for the Na+/Ca2+ exchanger NCX1 is characterized by a cluster of six exons (A, B, C, D, E, and F) coding for a variable region in the COOH terminus of the large intracellular loop of the protein. Alternative splicing of these exons generates multiple tissue-specific variants of NCX1. Using reverse transcriptase-polymerase chain reaction, we analyzed eight previously described and four new splicing isoforms of NCX1 in a wide variety of tissues and cells. Exons A and B are mutually exclusive, as shown in earlier studies, and splicing isoforms containing exon A are preferentially expressed in heart, brain, and skeletal muscle, whereas splicing variants with exon B are found in all rat tissues except heart. The second and third isoforms of the Na+/Ca2+ exchanger, NCX2 and NCX3, show a deletion of 37 amino acids in the intracellular loop corresponding to parts of the variable region of NCX1. We identified three splicing isoforms of NCX3 in brain and skeletal muscle by reverse transcriptase-polymerase chain reaction. These splice variants are generated by including either of two alternative exons equivalent to the NCX1 exon A or B and by including or excluding a sequence equivalent to the NCX1 exon C. We did not detect any alternative splicing of NCX2. We examined selected tissues from neonatal and adult rats and found developmental regulation for NCX1 and NCX3 splicing isoforms in skeletal muscle. Specific isoform patterns were also detected for NCX1 and NCX3 in cultured cortical neurons, astrocytes, and oligodendrocytes. We suggest a new terminology to distinguish the different splice variants of individual NCX isoforms.

Functional characterization of the Haemophilus influenzae 4.5S RNA

1998 ◽  
Vol 44 (1) ◽  
pp. 91-94
Author(s):  
G Scott Jenkins ◽  
Mark S Chandler ◽  
Pamela S Fink
Keyword(s):  
Haemophilus Influenzae ◽  
Functional Characterization ◽  
Coli Strain ◽  
Northern Analysis ◽  
Gene Encoding ◽  
E Coli ◽  
Functional Homolog ◽  
Polymerase Chain ◽  
4.5S Rna

The putative 4.5S RNA of Haemophilus influenzae was identified in the genome by computer analysis, amplified by the polymerase chain reaction, and cloned. We have determined that this putative 4.5S RNA will complement an Escherichia coli strain conditionally defective in 4.5S RNA production. The predicted secondary structures of the molecules were quite similar, but Northern analysis showed that the H. influenzae RNA was slightly larger than the E. coli RNA. The H. influenzae gene encoding this RNA is the functional homolog of the ffs gene in E. coli. Key words: ffs gene, complementation studies, small RNA, prokaryotic genetics.

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