scholarly journals Directional cues for growing axons forming the retinotectal projection

Development ◽  
1987 ◽  
Vol 101 (3) ◽  
pp. 479-489 ◽  
Author(s):  
A. Gierer
Keyword(s):  
Growth Cone ◽  
Target Position ◽  
Axonal Growth ◽  
Proximal Part ◽  
Connectivity Patterns ◽  
Wrong Direction ◽  
Directional Change ◽  
General Physical ◽  
Physical Principles

In the formation of projections that map one area of the nervous system onto another, guidance of axonal growth cones by directional cues encoded in target tissues is well established by observations on misrouted fibres, though other mechanisms contribute to the precision of connectivity patterns. General physical principles indicate that, if there is directional guidance of normally as well as misrouted axons, leading them toward their appropriate target positions, the inference for a role of graded distributions of molecules is a strong one. As explained in this paper, curving, meandering, branching and shifting connections are fully consistent with a crucial role of directional cues encoded by graded molecular distributions. A model is proposed according to which slight directional cues are strongly enhanced within the axonal growth cone; if the proximal part of the growth cone is activated indicating that the growth cone points in an entirely wrong direction, then a discontinuous directional change such as branching is elicited. Pathways are corrected in this way, and near the appropriate target position the terminal arbour is formed because from there all routes point towards less optimal positions, leading to multiple branching.

scholarly journals The role of nArgBP2 in the axonal growth cone

IBRO Reports ◽  
2019 ◽  
Vol 6 ◽  
pp. S471
Author(s):  
Jeayeok Hong ◽  
Hosung Jung
Keyword(s):  
Growth Cone ◽  
Axonal Growth ◽  
Axonal Growth Cone

scholarly journals The role of microtubule dynamics in growth cone motility and axonal growth.

1995 ◽  
Vol 128 (1) ◽  
pp. 139-155 ◽  
Author(s):  
E Tanaka ◽  
T Ho ◽  
M W Kirschner
Keyword(s):  
Growth Cone ◽  
Axonal Growth ◽  
Microtubule Dynamics ◽  
Low Doses ◽  
Direct Visualization ◽  
Forward Movement

The growth cone contains dynamic and relatively stable microtubule populations, whose function in motility and axonal growth is uncharacterized. We have used vinblastine at low doses to inhibit microtubule dynamics without appreciable depolymerization to probe the role of these dynamics in growth cone behavior. At doses of vinblastine that interfere only with dynamics, the forward and persistent movement of the growth cone is inhibited and the growth cone wanders without appreciable forward translocation; it quickly resumes forward growth after the vinblastine is washed out. Direct visualization of fluorescently tagged microtubules in these neurons shows that in the absence of dynamic microtubules, the remaining mass of polymer does not invade the peripheral lamella and does not undergo the usual cycle of bundling and splaying and the growth cone stops forward movement. These experiments argue for a role for dynamic microtubules in allowing microtubule rearrangements in the growth cone. These rearrangements seem to be necessary for microtubule bundling, the subsequent coalescence of the cortex around the bundle to form new axon, and forward translocation of the growth cone.

Physical and Biological Properties and Principles

2018 ◽  
Keyword(s):  
Biological Properties ◽  
Animal Locomotion ◽  
The Media ◽  
Key Dimensions ◽  
Scaling Analyses ◽  
Physical Principles

Studies of animal locomotion are grounded in an understanding of the physical principles that govern how animals move and properties of the media through which they move. These studies, in turn, explain why certain biological devices, such as a wing or a fin, share features that have evolved for movement within their particular fluid environments. In this chapter, we examine the role of the environment and the fundamentals of loading and forces in animal mechanics. We offer a quick review of scaling analyses as well as the key dimensions and units used in this book to assist with your appreciation of the information.

scholarly journals Differential Role of PTEN Phosphatase in Chemotactic Growth Cone Guidance

2013 ◽  
Vol 288 (29) ◽  
pp. 20837-20842 ◽  
Author(s):  
Steven J. Henle ◽  
Lucas P. Carlstrom ◽  
Thomas R. Cheever ◽  
John R. Henley
Keyword(s):  
Growth Cone ◽  
Essential Feature ◽  
Pten Expression ◽  
Spinal Neurons ◽  
Phosphoinositide Phosphatase ◽  
Integrin Clustering ◽  
Myelin Associated Glycoprotein ◽  
Phosphatase And Tensin Homologue ◽  
Regenerative Therapies

Negatively targeting the tumor suppressor and phosphoinositide phosphatase PTEN (phosphatase and tensin homologue) promotes axon regrowth after injury. How PTEN functions in axon guidance has remained unknown. Here we report the differential role of PTEN in chemotactic guidance of axonal growth cones. Down-regulating PTEN expression in Xenopus laevis spinal neurons selectively abolished growth cone chemorepulsion but permitted chemoattraction. These findings persisted during cAMP-dependent switching of turning behaviors. Live cell imaging using a GFP biosensor revealed rapid PTEN-dependent depression of phosphatidylinositol 3,4,5-trisphosphate levels in the growth cone induced by the repellent myelin-associated glycoprotein. Moreover, down-regulating PTEN expression blocked negative remodeling of β1-integrin adhesions triggered by myelin-associated glycoprotein, yet permitted integrin clustering by a positive chemotropic treatment. Thus, PTEN negatively regulates growth cone phosphatidylinositol 3,4,5-trisphosphate levels and mediates chemorepulsion, whereas chemoattraction is PTEN-independent. Regenerative therapies targeting PTEN may therefore suppress growth cone repulsion to soluble cues while permitting attractive guidance, an essential feature for re-forming functional neural circuits.

Role of dual leucine zipper-bearing kinase (DLK/MUK/ZPK) in axonal growth

2010 ◽  
Vol 66 (1) ◽  
pp. 37-45 ◽  
Author(s):  
Kaoru Eto ◽  
Takeshi Kawauchi ◽  
Makiko Osawa ◽  
Hidenori Tabata ◽  
Kazunori Nakajima
Keyword(s):  
Leucine Zipper ◽  
Axonal Growth

A monitoring system for axonal growth dynamics using micropatterns of permissive and Semaphorin 3F chemorepulsive signals

Lab on a Chip ◽  
2019 ◽  
Vol 19 (2) ◽  
pp. 291-305 ◽  
Author(s):  
Jae Ryun Ryu ◽  
June Hoan Kim ◽  
Hyo Min Cho ◽  
Youhwa Jo ◽  
Boram Lee ◽  
...  
Keyword(s):  
Monitoring System ◽  
Small Molecule ◽  
Growth Cone ◽  
Culture System ◽  
Small Molecule Inhibitors ◽  
Growth Dynamics ◽  
Axonal Growth ◽  
Screening System ◽  
Semaphorin 3F

Our dot array culture system can be used as a screening system to easily and efficiently evaluate ECM or small molecule inhibitors interfering growth cone dynamics leading to controlling axonal growth.

scholarly journals Gaya Kepemimpinan Pendidikan

2019 ◽  
Author(s):  
Nazmi Septiani
Keyword(s):  
Educational Leadership ◽  
Educational Goals ◽  
Work Team ◽  
Global Competition ◽  
Main Role ◽  
Organizational Goals ◽  
The People ◽  
Wrong Direction

Abstract-- Leadership or activities lead an effort by someone with all the ability they have to influence, encourage, direct and mobilize the people who led them to set to work with enthusiasm and confidence in achieving its goals. Educational leadership is a readiness, the ability of a person in the process of influencing, encouraging, guiding, directing and mobilizing others to do with the implementation and development of education and teaching so that all activities can be run effectively and efficiently in achieving educational goals. Leadership is an important part of management, namely planning and organizing, but the main role of leadership is to influence other people to achieve their intended goals. This is evidence that leaders may be weak managers if the planning is bad which causes the group to go in the wrong direction. As a result, although they can move the work team, they do not go towards achieving organizational goals. To address the challenges of globalization which is characterized by the presence of very tight and sharp global competition.

scholarly journals Altered calcium currents and axonal growth in Nf1 haploinsufficient mice

2010 ◽  
Vol 1 (2) ◽  
Author(s):  
Yuying Wang ◽  
Joel Brittain ◽  
Sarah Wilson ◽  
Cynthia Hingtgen ◽  
Rajesh Khanna
Keyword(s):  
Transmitter Release ◽  
Axonal Growth ◽  
Neurofibromatosis Type ◽  
Calcium Currents ◽  
Heterozygous Mutation ◽  
Excitatory Neurotransmitter ◽  
Cytoskeletal Dynamics ◽  
System Functioning ◽  
Common Learning

AbstractMutations of the neurofibromin gene (NF1) cause neurofibromatosis type 1 (NF1), a disease in which learning disabilities are common. Learning deficits also are observed in mice with a heterozygous mutation of Nf1 (Nf1 +/−). Dysregulation of regulated neurotransmitter release has been observed in Nf1 +/− mice. However, the role of presynaptic voltage-gated Ca2+ channels mediating this release has not been investigated. We investigated whether Ca2+ currents and transmitter release were affected by reduced neurofibromin in Nf1 +/− mice. Hippocampal Ca2+ current density was greater in neurons from Nf1 +/− mice and a greater fraction of Ca2+ currents was activated at less depolarized potentials. In addition, release of the excitatory neurotransmitter, glutamate, was increased in neuronal cortical cultures from Nf1 +/− mice. Dendritic complexity and axonal length were also increased in neurons Nf1 +/− mice compared to wild-type neurons, linking loss of neurofibromin to developmental changes in hippocampal axonal/cytoskeletal dynamics. Collectively, these results show that altered Ca2+ channel density and transmitter release, along with increased axonal growth may account for the abnormal nervous system functioning in NF1.

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