Homing behaviour of regenerating axons in the amphibian limb

Development ◽  
1989 ◽  
Vol 106 (4) ◽  
pp. 707-715
Author(s):  
S. Wilson ◽  
D.A. Tonge ◽  
N. Holder
Keyword(s):  
Electron Microscopy ◽  
Horseradish Peroxidase ◽  
Axon Regeneration ◽  
Axon Growth ◽  
Triturus Cristatus ◽  
Sequence Of Events ◽  
Growth Promoting ◽  
Directed Growth ◽  
Forearm Flexor ◽  
Over Time

Following peripheral nerve deviation in the limbs of urodele amphibians axons regrow distally toward their previous target muscles (Holder et al. 1984; Proc. Roy. Soc. Lond. B 222, 477–489). This study describes analysis of this axon regeneration over time following deviation of the forearm flexor nerve in Triturus cristatus and the extensor cranialis nerve in the axolotl. Using horseradish peroxidase (HRP) axonal tracing, electrophysiology and electron microscopy, we describe the sequence of events leading to reestablishment of functional innervation. HRP fills reveal axons leaving the deviated nerve via a number of possible routes and they invariably grow distally. Many axons take a path close to that of the original nerve but others fasciculate forming parallel paths. Electrophysiology and electron microscopy show that axons in the deviated region of the nerve degenerate extensively compared with cut, but undeviated, controls. The results are discussed in terms of the possible axon-growth-promoting mechanisms that result in directed growth.

scholarly journals Akt1-Inhibitor of DNA binding2 is essential for growth cone formation and axon growth and promotes central nervous system axon regeneration

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Hyo Rim Ko ◽  
Il-Sun Kwon ◽  
Inwoo Hwang ◽  
Eun-Ju Jin ◽  
Joo-Ho Shin ◽  
...  
Keyword(s):  
Growth Cone ◽  
Axonal Regeneration ◽  
Potential Role ◽  
Axon Regeneration ◽  
Hippocampal Slices ◽  
Axon Growth ◽  
Mechanistic Studies ◽  
Cone Formation ◽  
Growth Promoting ◽  
Inhibitor Of Dna Binding

Mechanistic studies of axon growth during development are beneficial to the search for neuron-intrinsic regulators of axon regeneration. Here, we discovered that, in the developing neuron from rat, Akt signaling regulates axon growth and growth cone formation through phosphorylation of serine 14 (S14) on Inhibitor of DNA binding 2 (Id2). This enhances Id2 protein stability by means of escape from proteasomal degradation, and steers its localization to the growth cone, where Id2 interacts with radixin that is critical for growth cone formation. Knockdown of Id2, or abrogation of Id2 phosphorylation at S14, greatly impairs axon growth and the architecture of growth cone. Intriguingly, reinstatement of Akt/Id2 signaling after injury in mouse hippocampal slices redeemed growth promoting ability, leading to obvious axon regeneration. Our results suggest that Akt/Id2 signaling is a key module for growth cone formation and axon growth, and its augmentation plays a potential role in CNS axonal regeneration.

scholarly journals Selective axonal translation of prenylated Cdc42 mRNA isoform supports axon growth

2018 ◽  
Author(s):  
Seung Joon Lee ◽  
Amar N. Kar ◽  
Matthew D. Zdradzinski ◽  
Priyanka Patel ◽  
Pabitra K. Sahoo ◽  
...  
Keyword(s):  
Axon Regeneration ◽  
Growth Promotion ◽  
Axon Growth ◽  
Alternatively Spliced ◽  
Selective Localization ◽  
Summary Statement ◽  
Growth Promoting ◽  
Axon Specification ◽  
Mrna Isoform

ABSTRACTThe small Rho-family GTPase Cdc42 has long been known to have a role in cell motility and axon growth. The eukaryotic CDC42 gene is alternatively spliced to generate mRNAs with two different 3’UTRs that encode proteins with distinct C-termini. The C-termini of these Cdc42 proteins include CAAX and CCAX motifs for post-translational prenylation and palmitoylation, respectively. Palmitoyl-Cdc42 protein was previously shown to contribute to dendrite maturation, while the prenyl-Cdc42 protein contributes to axon specification and its mRNA was detected in neurites. Here, we show that the mRNA encoding prenyl-Cdc42 isoform preferentially localizes into PNS axons and this localization selectively increases in vivo during PNS axon regeneration. Isoform specific siRNA knockdowns, rescue experiments with siRNA-resistant Cdc42 isoforms, and pharmacologically targeting Cdc42 activity indicate that prenyl-Cdc42 promotes axon growth while the palmitoyl-Cdc42 has little growth promoting activity. The growth promotion by prenyl-Cdc42 requires axonal mRNA localization with localized translation and an intact C-terminal CaaX motif for localized prenylation of the encoded protein. Together, these data show that alternative splicing of the CDC42 gene product generates an axon growth promoting locally synthesized prenyl-Cdc42 protein.SUMMARY STATEMENTAxon regeneration drives selective localization of alternatively spliced CDC42 isoform to PNS axons.

Comparative strengths and weaknesses of peroxidase and colloidal gold in pre- and post-embedding immunolabeling techniques

1987 ◽  
Vol 45 ◽  
pp. 1002-1005
Author(s):  
D. R. Abrahamson ◽  
P. L. St.John ◽  
E. W. Perry
Keyword(s):  
Electron Microscopy ◽  
Horseradish Peroxidase ◽  
Light Microscopy ◽  
Colloidal Gold ◽  
Light Microscope ◽  
Ultrastructural Localization ◽  
The Other ◽  
Quantitative Studies ◽  
Dense Suspension ◽  
Antigen Localization

Antibodies coupled to tracers for electron microscopy have been instrumental in the ultrastructural localization of antigens within cells and tissues. Among the most popular tracers are horseradish peroxidase (HRP), an enzyme that yields an osmiophilic reaction product, and colloidal gold, an electron dense suspension of particles. Some advantages of IgG-HRP conjugates are that they are readily synthesized, relatively small, and the immunolabeling obtained in a given experiment can be evaluated in the light microscope. In contrast, colloidal gold conjugates are available in different size ranges and multiple labeling as well as quantitative studies can therefore be undertaken through particle counting. On the other hand, gold conjugates are generally larger than those of HRP but usually can not be visualized with light microscopy. Concern has been raised, however, that HRP reaction product, which is exquisitely sensitive when generated properly, may in some cases distribute to sites distant from the original binding of the conjugate and therefore result in spurious antigen localization.

Albumin-Induced Endocytic Vacuoles in Tetrahymena Pyrijormis

1975 ◽  
Vol 33 ◽  
pp. 694-695
Author(s):  
L. J. Brenner ◽  
D. G. Osborne ◽  
B. L. Schumaker
Keyword(s):  
Electron Microscopy ◽  
Bovine Serum Albumin ◽  
Bovine Serum ◽  
Protein Concentration ◽  
Tetrahymena Pyriformis ◽  
Sequence Of Events ◽  
Cytoplasmic Bodies ◽  
Food Vacuoles ◽  
Mouse Ascites ◽  
Normal Human

Exposure of the ciliate, Tetrahymena pyriformis, strain WH6, to normal human or rabbit sera or mouse ascites fluids induces the formation of large cytoplasmic bodies. By electron microscopy these (LB) are observed to be membrane-bounded structures, generally spherical and varying in size (Fig. 1), which do not resemble the food vacuoles of cells grown in proteinaceous broth. The possibility exists that the large bodies represent endocytic vacuoles containing material concentrated from the highly nutritive proteins and lipoproteins of the sera or ascites fluids. Tetrahymena mixed with bovine serum albumin or ovalbumin solutions having about the same protein concentration (7g/100 ml) as serum form endocytic vacuoles which bear little resemblance to the serum-induced LB. The albumin-induced structures (Fig. 2) are irregular in shape, rarely spherical, and have contents which vary in density and consistency. In this paper an attempt is made to formulate the sequence of events which might occur in the formation of the albumin-induced vacuoles.

scholarly journals The Role of Lipids, Lipid Metabolism and Ectopic Lipid Accumulation in Axon Growth, Regeneration and Repair after CNS Injury and Disease

Cells ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1078
Author(s):  
Debasish Roy ◽  
Andrea Tedeschi
Keyword(s):  
Nervous System ◽  
Lipid Metabolism ◽  
Lipid Accumulation ◽  
Axon Regeneration ◽  
Axon Growth ◽  
The Body ◽  
Cns Repair ◽  
Cord Injury ◽  
Cns Trauma

Axons in the adult mammalian nervous system can extend over formidable distances, up to one meter or more in humans. During development, axonal and dendritic growth requires continuous addition of new membrane. Of the three major kinds of membrane lipids, phospholipids are the most abundant in all cell membranes, including neurons. Not only immature axons, but also severed axons in the adult require large amounts of lipids for axon regeneration to occur. Lipids also serve as energy storage, signaling molecules and they contribute to tissue physiology, as demonstrated by a variety of metabolic disorders in which harmful amounts of lipids accumulate in various tissues through the body. Detrimental changes in lipid metabolism and excess accumulation of lipids contribute to a lack of axon regeneration, poor neurological outcome and complications after a variety of central nervous system (CNS) trauma including brain and spinal cord injury. Recent evidence indicates that rewiring lipid metabolism can be manipulated for therapeutic gain, as it favors conditions for axon regeneration and CNS repair. Here, we review the role of lipids, lipid metabolism and ectopic lipid accumulation in axon growth, regeneration and CNS repair. In addition, we outline molecular and pharmacological strategies to fine-tune lipid composition and energy metabolism in neurons and non-neuronal cells that can be exploited to improve neurological recovery after CNS trauma and disease.

Axon Regeneration in Peripheral Nerves

2021 ◽  
Author(s):  
Arthur English
Keyword(s):  
Nerve Injury ◽  
Peripheral Nerves ◽  
Axon Regeneration ◽  
Axon Growth ◽  
Injury Site ◽  
Genetic Manipulations ◽  
Novel Treatments ◽  
The Central Nervous System ◽  
Experimental Treatments ◽  
Axonal Protein

Despite the intrinsically greater capacity for axons to regenerate in injured peripheral nerves than after injury to the central nervous system, functional recovery after most nerve injuries is very poor. A need for novel treatments that will enhance axon regeneration and improve recovery is substantial. Several such experimental treatments have been studied, each based on part of the stereotypical cellular responses that follow a nerve injury. Genetic manipulations of Schwann cells that have transformed from a myelinating to a repair phenotype that either increase their production of axon growth-promoting molecules, decrease production of inhibitors, or both result in enhanced regeneration. Local or systemic application of these molecules or small molecule mimetics of them also will promote regeneration. The success of treatments that stimulate axonal protein synthesis at the site of the nerve injury and in the growing axons, an early and important response to axon injury, is significant, as is that of manipulations of the types of immune cells that migrate into the injury site or peripheral ganglia. Modifications of the extracellular matrix through which the regenerating axons course, including the stimulation of new blood vessel formation, promotes the navigation of nascent regenerating neurites past the injury site, resulting in greater axon regeneration. Experimental induction of expression of regeneration associated gene activity in the cell bodies of the injured neurons is especially useful when regenerating axons must regenerate over long distances to reinnervate targets. The consistently most effective experimental approach to improving axon regeneration in peripheral nerves has been to increase the activity of the injured neurons, either through electrical, optical, or chemogenetic stimulation or through exercise. These activity-dependent experimental therapies show greatest promise for translation to use in patients.

Ultrastructural study of the avian ventral lateral geniculate nucleus

1991 ◽  
Vol 6 (2) ◽  
pp. 119-134 ◽  
Author(s):  
Gloria D. Guiloff
Keyword(s):  
Electron Microscopy ◽  
Horseradish Peroxidase ◽  
Lateral Geniculate Nucleus ◽  
Ultrastructural Study ◽  
Lateral Geniculate

AbstractThe ultrastructure of the pigeon and quail ventral lateral geniculate nucleus was analyzed with standard electron microscopy and horseradish peroxidase tracing of its retinal and tectal afferents. Six types of neurons were distinguished: two large, two medium-sized, and two small types.

scholarly journals ­­STAT3 combines with Rho-ROCK signaling pathway inhibitor, regulate axon growth of ganglion cells derived from retinal Müller cells

2020 ◽  
Author(s):  
xuezhi zhou ◽  
Yujue Wang ◽  
Manjuan Peng ◽  
Ye He ◽  
Jingjie Peng ◽  
...  
Keyword(s):  
Stem Cells ◽  
Layer Thickness ◽  
Axonal Regeneration ◽  
Axon Regeneration ◽  
Axon Growth ◽  
Müller Cells ◽  
Control Group ◽  
Marker Genes ◽  
Mrna Levels ◽  
Muller Cells

Abstract BackgroundMüller differentiated RGCs have potential therapeutic value for glaucoma. However, axonal regeneration of differentiated RGCs has been a difficult problem. Studies have confirmed that STAT3 and Y27632 play essential roles in regulating neuronal axon regeneration. Whether STAT3 and Y27632 can induce the Müller differentiated RGCs axon regeneration is still unknown.MethodRetina Müller cells were isolated and purified from Day 21 SD rats’ retina and were differentiated into retinal stem cells. The stem cells were randomly divided into five groups (control group, AAV-STAT3 group, shSTAT3 group, Y27632 group and AAV-STAT3 + Y27632 group). The axon length in each group were measured by ImageJ. Immunofluorescence were used to label the RGCs. The mRNA level of pluripotent associated and differentiation-associated proteins was analysed by qRT-PCR. Stem cells in different groups were injected into mice model of glaucoma. Immunohistochemical, Immunohistochemistry and OCT were performed to access RGC layer thickness in glaucoma model. VEP was used to detect the optic nerve conduction function.ResultsIn this study, we found that overexpression of STAT3 could promote the growth of RGCs axons generated by Müller cell differentiation. Combined with Y27632, axonal regeneration was significantly longer than that of the STAT3 group. However, after STAT3 was knocked out, axonal regeneration significantly decreased or even stopped. The mRNA levels of Esrrb, Prdm14, Sox2, and Rex1 in Müller differentiated RGCs after overexpression STAT3 combined with Y27632 were significantly increased, while the mRNA levels of Nestin, Eomes, Mixl1 and Gata4 were significantly decreased. The mRNA levels of Socs3, Pten, Klf9, and Mdm4 were significantly decreased, while the mRNA levels of Dclk2, Armcx1, C-MYC, and Nrn1 were significantly increased. The mRNA levels of differentiation and pluripotency marker genes showed opposite results after STAT3 deletion. After injecting Müller differentiated RGCs intervened by STAT3 combined with Y27632 into the eyes of the glaucoma model mice, the axon length, OCT displayed RGC layer thickness and the electrophysiology indicated by VEP were superior to those of the glaucoma model group.ConclusionsThese findings suggested that STAT3 combined with Y27632 can significantly improve the axonal growth level of RGCs, and reveal the potential mechanism to induce pluripotency of RGCs.

Who is Isaiah's Servant? Narrative identity and theological potentiality

2008 ◽  
Vol 61 (2) ◽  
pp. 125-136 ◽  
Author(s):  
Mark Gignilliat
Keyword(s):  
Narrative Identity ◽  
Real Life ◽  
The Self ◽  
Divine Action ◽  
Sequence Of Events ◽  
Unique Member ◽  
Divine Identity ◽  
Over Time

AbstractThe question ‘Who is the Servant?’ is one which remains a debated topic among many interpreters of Isaiah 40–55. This article seeks to address the same question with the aid and perspective of narrative identity. Narrative identity, as explicated by Ricoeur and Frei, is a means of understanding a character within a literary plot, or real life, as displayed in a narrated sequence of events. A person's identity, especially within literature, is the constancy of the self in the tortuous events of a narrated sequence over time. This article seeks to adjudicate the question of the Servant's identity by observing the character of the Servant within the plot of Isaiah 40–55. The conclusion drawn is that the Servant is the unique means of God's reconciliation of both Zion and the nations. Also, the divine action and description of YHWH and the Servant begin to bleed in such a way that the Servant can be described as a unique member of the divine identity.

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