scholarly journals Her9/Hes4 is required for retinal photoreceptor development, maintenance, and survival

2019 ◽  
Author(s):  
Cagney E. Coomer ◽  
Stephen G. Wilson ◽  
Kayla F. Titialii-Torres ◽  
Jessica D. Bills ◽  
Laura A. Krueger ◽  
...  
Keyword(s):  
Marginal Zone ◽  
Rod Photoreceptor ◽  
Lineage Specification ◽  
Extrinsic Factors ◽  
Helix Loop Helix ◽  
Retinal Photoreceptor ◽  
Vertebrate Photoreceptor ◽  
Photoreceptor Development ◽  
Ciliary Marginal Zone

AbstractThe intrinsic and extrinsic factors that regulate vertebrate photoreceptor specification and differentiation are complex, and our understanding of all the players is far from complete. Her9, the zebrafish ortholog of human HES4, is a basic helix-loop-helix-orange (bHLH-O) transcriptional repressor that regulates neurogenesis in several developmental contexts. We have previously shown that her9 is upregulated during chronic rod photoreceptor degeneration and regeneration in adult zebrafish, but little is known about the role of her9 during retinal development. To better understand the function of Her9 in the retina, we generated zebrafish her9 CRISPR mutants. Her9 homozygous mutants displayed striking retinal phenotypes, including decreased numbers of rods and red/green cones, whereas blue and UV cones were relatively unaffected. The reduction in rods and red/green cones correlated with defects in photoreceptor subtype lineage specification. The remaining rods and double cones displayed abnormally truncated outer segments, and elevated levels of apoptosis. In addition to the photoreceptor defects, her9 mutants also possessed a reduced proliferative ciliary marginal zone, and decreased and disorganized Müller glia. Mutation of her9 was larval lethal, with no mutants surviving past 13 days post fertilization. Our results reveal a previously undescribed role for Her9/Hes4 in photoreceptor differentiation, maintenance, and survival.

The photoreceptor cytoskeleton visualized

1992 ◽  
Vol 50 (1) ◽  
pp. 480-481
Author(s):  
Beth Burnside
Keyword(s):  
Outer Segment ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Cell Polarization ◽  
Synaptic Proteins ◽  
Cell Functions ◽  
Vertebrate Photoreceptor ◽  
Numerous Cell ◽  
Turn Over

The vertebrate photoreceptor provides a drammatic example of cell polarization. Specialized to carry out phototransduction at its distal end and to synapse with retinal interneurons at its proximal end, this long slender cell has a uniquely polarized morphology which is reflected in a similarly polarized cytoskeleton. Membranes bearing photopigment are localized in the outer segment, a modified sensory cilium. Sodium pumps which maintain the dark current critical to photosensory transduction are anchored along the inner segment plasma membrane between the outer segment and the nucleus.Proximal to the nucleus is a slender axon terminating in specialized invaginating synapses with other neurons of the retina. Though photoreceptor diameter is only 3-8u, its length from the tip of the outer segment to the synapse may be as great as 200μ. This peculiar linear cell morphology poses special logistical problems and has evoked interesting solutions for numerous cell functions. For example, the outer segment membranes turn over by means of a unique mechanism in which new disks are continuously added at the proximal base of the outer segment, while effete disks are discarded at the tip and phagocytosed by the retinal pigment epithelium. Outer segment proteins are synthesized in the Golgi near the nucleus and must be transported north through the inner segment to their sites of assembly into the outer segment, while synaptic proteins must be transported south through the axon to the synapse.The role of the cytoskeleton in photoreceptor motile processes is being intensely investigated in several laboratories.

Role of Vajraka Taila in the management of Vrana

2017 ◽  
Vol 2 (4) ◽  
Author(s):  
Ranjit Singh ◽  
Upasana Priya ◽  
Mahesh Chand Purvya
Keyword(s):  
The Other ◽  
Inclusion Criteria ◽  
Extrinsic Factors ◽  
External Application ◽  
Major Aspect

In today’s busy and fast life more people are living with conditions that increase their susceptibility to traumatic wounds, due to one or the other cause; thereby taking a heavy toll of life. As per Ayurveda, these type of wounds, which are caused by extrinsic factors are known as Sadyovrana. The major aspect of the management of the traumatic wounds is prevention of the infection, speedy healing, reducing pain, discharge and less discoloration after healing. In Ayurveda, various formulations for debridement are mentioned such as Kwaatha, Kalka, Churna, Rasakriya, Varti, Taila and Ghrita depending on the Avastha of Vrana. In the present study use of Vajraka Taila for external application, has been chosen. Total 30 patients fulfilling the inclusion criteria were selected and the treatment was given for 15 days. The study showed that Vajraka Taila is very effective in Vrana.

scholarly journals Crosstalk between NOTCH and AKT signaling during murine megakaryocyte lineage specification

Blood ◽  
2011 ◽  
Vol 118 (5) ◽  
pp. 1264-1273 ◽  
Author(s):  
Melanie G. Cornejo ◽  
Vinciane Mabialah ◽  
Stephen M. Sykes ◽  
Tulasi Khandan ◽  
Cristina Lo Celso ◽  
...  
Keyword(s):  
Stem Cell ◽  
Notch Signaling ◽  
Signaling Pathway ◽  
Hematopoietic Stem Cell ◽  
Stem Cell Differentiation ◽  
Notch Signaling Pathway ◽  
Developmental Pathways ◽  
Lineage Specification ◽  
Hematopoietic Stem

Abstract The NOTCH signaling pathway is implicated in a broad range of developmental processes, including cell fate decisions. However, the molecular basis for its role at the different steps of stem cell lineage commitment is unclear. We recently identified the NOTCH signaling pathway as a positive regulator of megakaryocyte lineage specification during hematopoiesis, but the developmental pathways that allow hematopoietic stem cell differentiation into the erythro-megakaryocytic lineages remain controversial. Here, we investigated the role of downstream mediators of NOTCH during megakaryopoiesis and report crosstalk between the NOTCH and PI3K/AKT pathways. We demonstrate the inhibitory role of phosphatase with tensin homolog and Forkhead Box class O factors on megakaryopoiesis in vivo. Finally, our data annotate developmental mechanisms in the hematopoietic system that enable a decision to be made either at the hematopoietic stem cell or the committed progenitor level to commit to the megakaryocyte lineage, supporting the existence of 2 distinct developmental pathways.

scholarly journals Purinergic Signals Regulate Daily S-Phase Cell Activity in the Ciliary Marginal Zone of the Zebrafish Retina

2011 ◽  
Vol 26 (2) ◽  
pp. 107-117 ◽  
Author(s):  
Maria Jimena Ricatti ◽  
Ariadna Gabriela Battista ◽  
Maria Zorrilla Zubilete ◽  
Maria Paula Faillace
Keyword(s):  
Marginal Zone ◽  
Cell Activity ◽  
S Phase ◽  
Phase Cell ◽  
Ciliary Marginal Zone

Differential regulation of granulopoiesis by the basic helix-loop-helix transcriptional inhibitors Id1 and Id2

Blood ◽  
2005 ◽  
Vol 105 (11) ◽  
pp. 4272-4281 ◽  
Author(s):  
Miranda Buitenhuis ◽  
Hanneke W. M. van Deutekom ◽  
Liesbeth P. Verhagen ◽  
Anders Castor ◽  
Sten Eirik W. Jacobsen ◽  
...  
Keyword(s):  
Critical Role ◽  
Ectopic Expression ◽  
Constitutive Expression ◽  
Retroviral Transduction ◽  
Basic Helix Loop Helix ◽  
Helix Loop Helix ◽  
Cd34 Cells ◽  
Final Maturation ◽  
Inhibitor Of Dna Binding

Abstract Inhibitor of DNA binding (Id) proteins function as inhibitors of members of the basic helix-loop-helix family of transcription factors and have been demonstrated to play an important role in regulating lymphopoiesis. However, the role of these proteins in regulation of myelopoiesis is currently unclear. In this study, we have investigated the role of Id1 and Id2 in the regulation of granulopoiesis. Id1 expression was initially up-regulated during early granulopoiesis, which was then followed by a decrease in expression during final maturation. In contrast, Id2 expression was up-regulated in terminally differentiated granulocytes. In order to determine whether Id expression plays a critical role in regulating granulopoiesis, Id1 and Id2 were ectopically expressed in CD34+ cells by retroviral transduction. Our experiments demonstrate that constitutive expression of Id1 inhibits eosinophil development, whereas in contrast neutrophil differentiation was modestly enhanced. Constitutive Id2 expression accelerates final maturation of both eosinophils and neutrophils, whereas inhibition of Id2 expression blocks differentiation of both lineages. Transplantation of β2-microglobulin-/- nonobese diabetic severe combined immunodeficient (NOD/SCID) mice with CD34+ cells ectopically expressing Id1 resulted in enhanced neutrophil development, whereas ectopic expression of Id2 induced both eosinophil and neutrophil development. These data demonstrate that both Id1 and Id2 play a critical, although differential role in granulopoiesis.

scholarly journals The ciliary marginal zone of the zebrafish retina: clonal and time-lapse analysis of a continuously growing tissue

Development ◽  
2016 ◽  
Vol 143 (7) ◽  
pp. 1099-1107 ◽  
Author(s):  
Yinan Wan ◽  
Alexandra D. Almeida ◽  
Steffen Rulands ◽  
Naima Chalour ◽  
Leila Muresan ◽  
...  
Keyword(s):  
Marginal Zone ◽  
Time Lapse ◽  
Ciliary Marginal Zone

scholarly journals THE ULTRASTRUCTURE OF LIPID-DEPLETED ROD PHOTORECEPTOR MEMBRANES

1974 ◽  
Vol 63 (2) ◽  
pp. 587-598 ◽  
Author(s):  
Izhak Nir ◽  
Michael O. Hall
Keyword(s):  
Lipid Extraction ◽  
Fatty Acid Analysis ◽  
Major Protein ◽  
Rod Photoreceptor ◽  
Thin Sections ◽  
Retinal Rod ◽  
Layer Chromatography ◽  
Chloroform Methanol ◽  
Photoreceptor Membranes

The structure of lipid-depleted retinal rod photoreceptor membranes was studied by means of electron microscopy. Aldehyde-fixed retinas were exhaustively extracted with acetone, chloroform-methanol, and acidified chloroform-methanol. The effect of prefixation on the extractability of lipids was evaluated by means of thin-layer chromatography and fatty acid analysis. Prefixation with glutaraldehyde rendered 38% of the phospholipids unextractable, while only 7% were unextractable after formaldehyde fixation. Embedding the retina in a lipid-retaining, polymerizable glutaraldehyde-urea mixture allows a comparison of the interaction of OsO4 with lipid-depleted membranes and rod disk membranes which contain all their lipids. A decrease in electron density and a deterioration of membrane fine structure in lipid-depleted tissue are correlated with the extent of lipid extraction. These observations are indicative of the role of the lipid bilayer in the ultrastructural visualization of membrane structure with OsO4. Negatively stained thin sections of extracted tissue reveal substructures in the lipid-depleted rod membranes. These substructures are probably the opsin molecules which are the major protein component of retinal rod photoreceptor membranes.

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