|
|
|
|
|
|
|
|
|||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | |||||
|
Fig. 1. Discrimination between neurotrophic factors (NTF)-dependent and NTF-independent types of axonal growth in DRG neurons. (A) After 12 hours in culture DRG neurons exhibit substantial axonal growth in presence of NGF or NRTN or GDNF (b) but not in control culture (no neurotrophic factors) (a). For quantification see Fig. 2A. NTF in all figures stands for treatment with NGF or NRTN or GDNF. After 40 hours in culture, axonal growth occurs equally in the presence (d) or in the absence (c) of exogenous neurotrophic factors. For quantification see Fig. 2B and Fig. 7A. All cultures were maintained on coverslips precoated with laminin. No outgrowth was observed in the absence of laminin precoating both at 12 hours and 40 hours in culture. Bars, 20 µm. Control, absence of treatments that are specified otherwise. (B) The `truth table' summarizing the axonal growth dependence on laminin and NTF. Binary mode (`+' or `–') was used to describe output data of the assay (presence or absence of axonal growth, respectively). For input conditions: +, treatment with laminin or NTF; –, absence of treatment. (C) At 12 hours in culture, axonal growth takes place only if laminin and NTF are present together. This kind of input-output relation is described by the conjunctive (AND) operation. (D) At 40 hours in culture, laminin is able to trigger axonal growth in the absence of NTFs, meaning that a separate, NTF-independent pathway exists. NTF-dependent and NTF-independent pathways converge on the axonal growth machinery and each pathway alone is sufficient to cause outgrowth. This kind of input-output relationship is described by the disjunctive operation (OR). NTF-dependent pathway is shown in red, NTF-independent in blue, and the common part of the two pathways in green.
|
