Dendrites transport

Finally, this section has focused almost entirely on axonal transport, but dendritic transport also occurs [25]. Since dendrites usually include postsynaptic regions while most axons terminate in presynaptic elements, the dendritic and axonal transport each receive a number of unique proteins. An added level of complexity for intraneuronal transport phenomena is the intriguing observation that mRNA is routed into dendrites where it is implicated in local protein synthesis at postsynaptic sites, but ribosomal components and mRNA are largely excluded from axonal domains [26]. Regulation of protein synthesis in dendritic compartments is an important mechanism is synaptic plasticity [27,28]. The importance of dendritic mRNA transport and local protein synthesis is underscored by the demonstration that the mutation associated with Fragile X syndrome affects a protein important for transport and localization of mRNA in dendrites [27, 29], Similar processes of mRNA transport have been described in glial cells [30]. 

Van Der Ende, A. et al. (2009) Tailored polyester nanoparticles post-modification with dendritic transporter and targeting units via reductive amination and thiol-ene chemistry. Soft Matter, 5,1417-1425. 

A major difference between the classical transmitters and peptides is that the production of a peptide is quite different since the synthesis of a peptide is in the form of a huge precursor of about 300 amino acids which is produced in the nucleus of the cell and then transported to the terminal being processed en route (Fig. 12.1). The prepropeptide is produced by translation in ribosomes and so occurs only in cell bodies or dendrites while the classical transmitters are produced at the terminal via a short series of enzymatic steps from a simple precursor. The study of the production of the propeptides have revealed a series of principles in that ... 

It is usually believed that the growth of dendritic crystals is controlled by a bulk diffusion-controlled process which is defined as a process controlled by a transportation of solute species by diffusion from the bulk of aqueous solution to the growing crystals (e.g., Strickland-Constable, 1968 Liu et al., 1976). The appearances of feather- and star-like dendritic shapes indicate that the concentrations of pertinent species (e.g., Ba +, SO ) in the solution are highest at the corners of crystals. The rectangular (orthorhombic) crystal forms are generated where the concentrations of solute species are approximately the same for all surfaces but it cannot be homogeneous when the consumption rate of solute is faster than the supply rate by diffusion (Nielsen, 1958). 

Dendritic cells (DCs) are bone marrow-derived professional antigen-presenting cells (APCs) (1). The function of DCs depends on their maturation stages progenitors in the bone marrow, precursors in the blood, immature DCs in peripheral tissues, antigen-transporting DCs in the afferent lymphatics, and... 

Host-guest systems made from dendritic materials have potential in the areas of membrane transport and drug delivery [68, 84, 85]. In a recent report [136] Tomalia and coworkers investigated structural aspects of a series of PAM AM bolaamphiphiles (e.g., 50) with a hydrophobic diamino do decane core unit. Fluorescence emission of added dye (nile red) was significantly enhanced in an aqueous medium in the presence of 50 unlike the cases when 51 and 52 were added (Fig. 23). Addition of anion surfactants to this mixture generated supramolecular assemblies which enhanced their ability (ca.by 10-fold) to accommodate nile red (53). Further increase in emission was noted by decreasing the pH from the normal value of 11 for PAMAM dendrimers to 7. At lower pH values the... 

Recently, another class of MAPs has been identified that lead to depolymerization of MT, stathmin and katanin [11], Stathmin destabilizes MT either by reducing available tubulin dimer or by altering the frequency of catastrophe at MT plus ends [18]. In contrast, katanin is an ATP-ase that severs MT [19]. In neurons, one important role of katanin is to release the MT from the MTOC and allow transport of the assembled MT into axons and dendrites. 

As axons and dendrites mature, their differences become more apparent [9]. In axons, MTs have a uniform orientation with plus-ends distal to the cell body, but dendrites contain MTs in both orientations. Dendrites and to a lesser extent perikarya contain MAP2, which is excluded from axons at an early stage. Curiously, MAP2 mRNA is one of several mRNAs that are specifically transported... 

Tao-Cheng, J. H. and Zhou, F. C. Differential Polarization of serotonin transporters in axons versus soma-dendrites an immunogold electron microscopy study. Neuroscience 94 821-830, 1999. 

The size and extent of many neurons presents a special set of challenges. Since protein synthesis for the entire neuron takes place in the cell body, which may represent only 0.1% of the total cell volume, growth and maintenance of neuronal processes requires timely, efficient delivery of material to axonal and dendritic domains. The idea that materials must be transferred from cell body to axon was suggested by Ramon y Cajal and other pioneers during the early part of this century. For many years, the existence of such transport processes could only be inferred. 

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