A SxIP motif interaction at the microtubule plus end is important for processive retrograde axonal transport

The retrograde transport of endosomes within axons proceeds with remarkable uniformity despite having to navigate a discontinuous microtubule network. The mechanisms through which this navigation is achieved remain elusive. In this report, we demonstrate that access of SxIP motif proteins, such as BPAG1n4, to the microtubule plus end is important for the maintenance of processive and sustained retrograde transport along the axon. Disruption of this interaction at the microtubule plus end significantly increases endosome stalling. Our study thus provides strong insight into the role of plus-end-binding proteins in the processive navigation of cargo within the axon.     

Localization of motoneurones of retractor bulbi muscles by retrograde transport of exogenous peroxidase in cats]

Retrograde transport of exogene horseradish peroxidase has been used to localize the retractor bulbi muscle motoneurones. These motoneurones are located ventro-laterally in the tegmental reticular field; they are grouped in a rostro-caudal column above the superior olive. They correspond to the accessory nucleus of the VIe nerve described by old anatomists.     

Impairment of rapid axonal transport and concomitant anomaly of smooth endoplasmic reticulum in acrylamide induced neuropathy]

The axonal transport of proteins was studied by radioautography in preganglionic axons of ciliary ganglia in Leghorn chickens treated by acrylamide. The slow axonal transport of proteins was hardly affected. In contrast, the fast axonal transport was severely impaired. Indeed, radioactive proteins accumulated focally at the periphery of several preterminal axons in regions showing a local disorganization of the smooth endoplasmic reticulum which seemed to be one of the earliest changes induced by acrylamide.     

Colchicine may interfere with the axonal transport of noradrenaline in the central noradrenergic neurons

Summary The administration of colchicine (50 g) into the lateral ventricles induced the marked accumulation of noradrenaline in the locus coeruleus of rat. Lumicolchicine administration or stress loading failed to alter the noradrenaline levels, thus suggesting that this accumulation is related to the blockade of axonal flow in the central noradrenergic neurons.Acknowledgment. Authors thank Drs Y. Kakimoto and M. Miyake for their advice on the assay of catecholamines.     

Changes in the histochemical nature of neurosecretory materials during axonal transport in the CrabParagrapsus gaimardii

Résumé Dans le système neurosécréteur du pédoncule oculaire et les organes péricardiques du crabeParagrapsus gaimardii, la direction du processus de modification du produit de neurosécrétion durant le cheminement axonal semble Être de sens opposé à celle qu'on observe chez les insectes et les grenouilles.     

Application of the ion-thinning methods to the high-resolution study of human dental enamel crystals]

Ion thinning technique applied to high resolution T.E.M. study of human dental enamel crystallites makes it possible to visualize a great number of dislocations. Dislocations proved not to be due to artifacts induced by the ultramicrotome diamond knife. They are related to the crystal apartite structure.     

Short-term effects of colcemid on the rapid axonal transport of proteins in the optic pathway of chick embryos

Riassunto La somministrazione endoculare di piccole dosi di Colcemid in embrioni di pollo al 13° e al 18° giorno di incubazione diminuisce la sintesi proteica nella retina. Pur in misura diversa, i due farmaci bloccano il trasporto assonico di proteine dalle cellule gangliari retiniche al tetto ottico. Anche nell'embrione quindi il trasporto assonico dipende dalla integrità dei microtubuli neuronali.

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This work was supported by Consiglio Nazionale delle Ricerche (C.N.R.), Rome, Italy.     

Combined axonal transport tracing and immunocytochemistry for mapping pathways of peptide-containing nerves in the peripheral nervous system

The various combinations of axonal transport tracing and immunocytochemistry used for mapping pathways of peptide-containing nerves, and in particular those of the peripheral nervous system, are reviewed. The advantages and disadvantages of these methods are discussed. The applications and results presented illustrate the future potential value of this approach.     

Combined axonal transport tracing and immunocytochemistry for mapping pathways of peptide-containing nerves in the peripheral nervous system

Summary The various combinations of axonal transport tracing and immunocytochemistry used for mapping pathways of peptide-containing nerves, and in particular those of the peripheral nervous system, are reviewed. The advantages and disadvantages of these methods are discussed. The applications and results presented illustrate the future potential value of this approach.     

Non-enzymatic active transport in vitro. Conversion of chemical to osmotic energy]

The active transport of ammonia gas was obtained with an asymmetric composite membrane-model using H+ as carrier and the formation of water as chemical energy source. The experimental molecular pump externally limited by two silicone films permeable to gasses but not to liquids or ions is separated into two liquid layers by a central cation-exchange membrane. The first acid layer produces the aspiration of NH3, due to NH4+ formation, through the inlet silicone film; NH4+ is transferred to the second alkaline layer through the ion exchange membrane, by interdiffusion with K+; there NH4+ reacts with OH-, water is formed and NH3 is expelled throught the oulet silicone film. This new pump enlarges the applicability of in vitro active transport to non-enzymatic systems and energy sources different from ATP.     

Pharmacological study of para-aminoclonidine, an alpha sympathomimetic]

Para-aminoclonidine is a more potent alpha-adrenergic agent than clonidine; in vitro on Rat aorta it is 150 times more active than NE, in vivo on pithed Rat it is still twice as active. The hypotensive action of paraaminoclondine is only manifested when given intraventricularly. In the conscious Rat, it has a diuretic action when given per os. Following IV injection in the anaesthetized Dog, the para-aminoclonidine induces an essentially hydric diuresis which is independet of its hypertensive action.     

Autoradiographic study of a bacterial colony. Application to the effects of polymyxin on Pseudomonas aeruginosa colonies]

The autoradiograph of a colony of Ps. a. which has been transferred, during growth, on a medium added with polymyxin and tritiate leucin makes it possible to locate an upper zone with a high metabolic activity and a basal zone with no metabolic activity. The latter, which consists of lysed cells, acts probably as a selective filter against the drug.     

Differential neuronal radiosensitivity as a tool for the study of short connections

Résumé La radiolésion aigue du bulbe olfactif provoque des dommages sélectifs aux petits interneurons. L'examen au microscope électronique du tissu irradié a mis en évidence la présence de nombreuses terminales en dégénérescence, au niveau de la couche plexiforme. Elles ont été interprétées comme étant des dendrites appartenant aux granules radiolésées par leur position post-synaptique dans des synapses réciproques avec des dendrites mitrals. On propose d'utiliser cette méthode pour l'étude des connections interneuronales courtes dans certains endroits du SNC.

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This work was partially supported by grants from the Medica Research Council of Canada and Conseil Medical de la Recherche du Québec.     

Biochemistry,evolution and physiological function of the Rnf complex,a novel ion-motive electron transport complex in prokaryotes

Microbes have a fascinating repertoire of bioenergetic enzymes and a huge variety of electron transport chains to cope with very different environmental conditions, such as different oxygen concentrations, different electron acceptors, pH and salinity. However, all these electron transport chains cover the redox span from NADH + H⁺ as the most negative donor to oxygen/H₂O as the most positive acceptor or increments thereof. The redox range more negative than −320 mV has been largely ignored. Here, we have summarized the recent data that unraveled a novel ion-motive electron transport chain, the Rnf complex, that energetically couples the cellular ferredoxin to the pyridine nucleotide pool. The energetics of the complex and its biochemistry, as well as its evolution and cellular function in different microbes, is discussed.     

Histofluorescence of catecholamines and visualization of retrograde transported peroxidase in the same tissue section and in the same neuron]

The demonstration of fluorescent catecholamines and horseradish peroxidase (HRP) in the same neuron has been achieved in the Rat in two ways: by submitting vibratome sections to a modified glyoxylic acid fluorescence method followed by the usual procedure to reveal HRP; or by combining the last procedure with the cryostat technique of Chiba et coll. After HRP injection into the striatum or the nucleus accumbens of the Rat, non-fluorescent HRP labelled neurons were observed in the substantia nigra and the ventral tegmental area respectively, in addition to the HRP labelled fluorescent dopaminergic neurons.