scholarly journals Dynamic Polarization of Rab11a Modulates Crb2a Localization and Impacts Signaling to Regulate Retinal Neurogenesis

2021 ◽  
Vol 8 ◽  
Author(s):  
Brian S. Clark ◽  
Joel B. Miesfeld ◽  
Michael A. Flinn ◽  
Ross F. Collery ◽  
Brian A. Link
Keyword(s):  
Mitotic Cycle ◽  
Genetic Manipulation ◽  
Nuclear Migration ◽  
Dynamic Polarization ◽  
Recycling Endosomes ◽  
Interkinetic Nuclear Migration ◽  
Mechanistic Insight ◽  
Functional Analyses ◽  
Multiple Signaling ◽  
Selection Of

Interkinetic nuclear migration (IKNM) is the process in which pseudostratified epithelial nuclei oscillate from the apical to basal surface and in phase with the mitotic cycle. In the zebrafish retina, neuroepithelial retinal progenitor cells (RPCs) increase Notch activity with apical movement of the nuclei, and the depth of nuclear migration correlates with the probability that the next cell division will be neurogenic. This study focuses on the mechanisms underlying the relationships between IKNM, cell signaling, and neurogenesis. In particular, we have explored the role IKNM has on endosome biology within RPCs. Through genetic manipulation and live imaging in zebrafish, we find that early (Rab5-positive) and recycling (Rab11a-positive) endosomes polarize in a dynamic fashion within RPCs and with reference to nuclear position. Functional analyses suggest that dynamic polarization of recycling endosomes and their activity within the neuroepithelia modulates the subcellular localization of Crb2a, consequently affecting multiple signaling pathways that impact neurogenesis including Notch, Hippo, and Wnt activities. As nuclear migration is heterogenous and asynchronous among RPCs, Rab11a-affected signaling within the neuroepithelia is modulated in a differential manner, providing mechanistic insight to the correlation of IKNM and selection of RPCs to undergo neurogenesis.

scholarly journals WUSCHEL Overexpression Promotes Callogenesis and Somatic Embryogenesis in Medicago truncatula Gaertn

Plants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 715
Author(s):  
Aline Kadri ◽  
Ghislaine Grenier De March ◽  
François Guerineau ◽  
Viviane Cosson ◽  
Pascal Ratet
Keyword(s):  
Somatic Embryogenesis ◽  
Medicago Truncatula ◽  
Transformation Efficiency ◽  
Genetic Manipulation ◽  
Leaf Explants ◽  
Promising Tool ◽  
Limiting Step ◽  
Wus Gene ◽  
Multiple Signaling ◽  
Regeneration Systems

The induction of plant somatic embryogenesis is often a limiting step for plant multiplication and genetic manipulation in numerous crops. It depends on multiple signaling developmental processes involving phytohormones and the induction of specific genes. The WUSCHEL gene (WUS) is required for the production of plant embryogenic stem cells. To explore a different approach to induce somatic embryogenesis, we have investigated the effect of the heterologous ArabidopsisWUS gene overexpression under the control of the jasmonate responsive vsp1 promoter on the morphogenic responses of Medicago truncatula explants. WUS expression in leaf explants increased callogenesis and embryogenesis in the absence of growth regulators. Similarly, WUS expression enhanced the embryogenic potential of hairy root fragments. The WUS gene represents thus a promising tool to develop plant growth regulator-free regeneration systems or to improve regeneration and transformation efficiency in recalcitrant crops.

Interkinetic nuclear migration in the tracheal and esophageal epithelia of the mouse embryo: Possible implications for tracheo-esophageal anomalies

2017 ◽  
Vol 58 (2) ◽  
pp. 62-70 ◽  
Author(s):  
Ryo Kaneda ◽  
Yuko Saeki ◽  
Dereje Getachew ◽  
Akihiro Matsumoto ◽  
Motohide Furuya ◽  
...  
Keyword(s):  
Mouse Embryo ◽  
Nuclear Migration ◽  
Interkinetic Nuclear Migration

scholarly journals Cephalopod Retinal Development Shows Vertebrate-like Mechanisms of Neurogenesis

2021 ◽  
Author(s):  
Francesca Napoli ◽  
Christina M Daly ◽  
Stephanie Neal ◽  
Kyle J McCulloch ◽  
Alexandra Zaloga ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Nervous System ◽  
Progenitor Cells ◽  
Cellular Proliferation ◽  
Imaging Techniques ◽  
Nuclear Migration ◽  
Live Imaging ◽  
Cellular Mechanisms ◽  
High Resolution Data ◽  
Interkinetic Nuclear Migration

Neurogenesis, the regulation of cellular proliferation and differentiation in the developing nervous system, is the process that underlies the diversity of size and cell type found in animal nervous systems. Our understanding of how this process has evolved is limited because of the lack of high resolution data and live-imaging methods across species. The retina is a classic model for the study of neurogenesis in vertebrates and live-imaging of the retina has shown that during development, progenitor cells are organized in a pseudostratified neuroepithelium and nuclei migrate in coordination with the cell cycle along the apicobasal axis of the cell, a process called interkinetic nuclear migration. Eventually cells delaminate and differentiate within the boundaries of the epithelium. This process has been considered unique to vertebrates and thought to be important in maintaining organization during the development of a complex nervous system. Coleoid cephalopods, including squid, cuttlefish and octopus, have the largest nervous system of any invertebrate and convergently-evolved camera-type eyes, making them a compelling comparative system to vertebrates. Here we have pioneered live-imaging techniques to show that the squid, Doryteuthis pealeii, displays cellular mechanisms during cephalopod retinal neurogenesis that are hallmarks of vertebrate processes. We find that retinal progenitor cells in the squid undergo interkinetic nuclear migration until they exit the cell cycle, we identify retinal organization corresponding to progenitor, post-mitotic and differentiated cells, and we find that Notch signaling regulates this process. With cephalopods and vertebrates having diverged 550 million years ago, these results suggest that mechanisms thought to be unique to vertebrates may be common to highly proliferative neurogenic primordia contributing to a large nervous system.

scholarly journals Gap Junctions/Hemichannels Modulate Interkinetic Nuclear Migration in the Forebrain Precursors

2010 ◽  
Vol 30 (12) ◽  
pp. 4197-4209 ◽  
Author(s):  
X. Liu ◽  
K. Hashimoto-Torii ◽  
M. Torii ◽  
C. Ding ◽  
P. Rakic
Keyword(s):  
Gap Junctions ◽  
Nuclear Migration ◽  
Interkinetic Nuclear Migration

scholarly journals The Bacterial Phytoene Desaturase-Encoding Gene (CRTI) is an Efficient Selectable Marker for the Genetic Transformation of Eukaryotic Microalgae

Metabolites ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 49 ◽  
Author(s):  
Ana Molina-Márquez ◽  
Marta Vila ◽  
Javier Vigara ◽  
Ana Borrero ◽  
Rosa León
Keyword(s):  
Genetic Transformation ◽  
Selectable Marker ◽  
Genetic Manipulation ◽  
Plant Cells ◽  
Phytoene Desaturase ◽  
Carotenoid Content ◽  
Great Promise ◽  
Encoding Gene ◽  
Average Transformation ◽  
Selection Of

Genetic manipulation shows great promise to further boost the productivity of microalgae-based compounds. However, selection of microalgal transformants depends mainly on the use of antibiotics, which have raised concerns about their potential impacts on human health and the environment. We propose the use of a synthetic phytoene desaturase-encoding gene (CRTIop) as a selectable marker and the bleaching herbicide norflurazon as a selective agent for the genetic transformation of microalgae. Bacterial phytoene desaturase (CRTI), which, unlike plant and algae phytoene desaturase (PDS), is not sensitive to norflurazon, catalyzes the conversion of the colorless carotenoid phytoene into lycopene. Although the expression of CRTI has been described to increase the carotenoid content in plant cells, its use as a selectable marker has never been testedin algae or in plants. In this study, a version of the CRTI gene adapted to the codon usage of Chlamydomonas has been synthesized, and its suitability to be used as selectable marker has been shown. The microalgae were transformed by the glass bead agitation method and selected in the presence of norflurazon. Average transformation efficiencies of 550 colonies µg−1 DNA were obtained. All the transformants tested had incorporated the CRTIop gene in their genomes and were able to synthesize colored carotenoids.

scholarly journals THE ULTRASTRUCTURE OF A MAMMALIAN CELL DURING THE MITOTIC CYCLE

1964 ◽  
Vol 21 (3) ◽  
pp. 429-463 ◽  
Author(s):  
Elliott Robbins ◽  
Nicholas K. Gonatas
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Mitotic Cycle ◽  
Mitotic Cell ◽  
Multivesicular Bodies ◽  
Chromosome Movement ◽  
Living State ◽  
Characteristic Points ◽  
Circumferential Distribution ◽  
Selection Of

With a technique of preselecting the mitotic cell in the living state for subsequent electron microscopy, it has been possible to examine the ultrastructure of the various stages of mitosis with greater precision than has been reported previously. The early dissolution of the nuclear envelope has been found to be preceded by a marked undulation of this structure within the nuclear "hof." This undulation appears to be intimately related to the spindle-forming activity of the centriole at this time. Marked pericentriolar osmiophilia and extensive arrays of vesicles are also prominent at this stage, the former continuing into anaphase. Progression of the cell through prophase is accompanied by a disappearance of these vesicles. A complex that first makes its appearance in prophase but becomes most prominent in metaphase is a partially membrane-bounded cluster of dense osmiophilic bodies. These clusters which have a circumferential distribution in the mitotic cell are shown to be derived from multivesicular bodies and are acid phosphatase-positive. The precise selection of cells during the various stages of anaphase has made it possible to follow chronologically the morphological features of the initiation of nuclear membrane reformation. The nuclear membrane appears to be derived from polar aggregates of endoplasmic reticulum, and the process begins less than 2 minutes after the onset of karyokinesis. While formation of the nuclear envelope is initiated on the polar aspects of the chromatin mass, envelope elements appear on the equatorial aspect long before the polar elements fuse. Apparently interfering with this fusion are continuous spindle tubules which traverse the chromatin mass in striking density at characteristic points. Several cortical changes, also most pronounced in anaphase, have been described, as has the kinetochore which is seen to good advantage only in this stage. The Golgi complex has been found to disappear both morphologically and histochemically during mitosis and to reappear rapidly in telophase. Evidence is presented which implicates the continuous spindle tubules in certain phases of chromosome movement.

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