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Primordial germ cell (PGC) migration in zebrafish is directed by the chemokine SDF-1a that activates its receptor CXCR4b. Little is known about the molecular mechanisms controlling the distribution of this chemoattractant in vivo. We demonstrate that the activity of a second SDF-1/CXCL12 receptor, CXCR7, is crucial for proper migration of PGCs toward their(More)
Zebrafish primordial germ cells (PGCs) are guided toward their targets by the chemokine SDF-1a. PGCs were followed during three phases of their migration: when migrating as individual cells, while remaining in a clustered configuration, and when moving as a cell cluster within the embryo. We found that individually migrating PGCs alternate between migratory(More)
Activation of the chemokine receptor CXCR4 by SDF1 controls a variety of biological processes in development, immune response, and disease [1-5]. The carboxyl-terminal region of CXCR4 is subject to phosphorylation that allows binding of regulatory proteins [5]; this results in downregulation of CXCR4 signaling and receptor internalization [6]. Notably,(More)
Depolarization of neuron membrane was shown to occur during cAMP injection by means of both iontophoresis and pressure. Distension of the neuron by means of blowing with large volumes of solution without cAMP can produce reversible responses. The time course can be made similar to that of the cAMP effect and the responses can be repeated many times in the(More)
The depolarization of neuronal membrane during cAMP injection by means of both iontophoresis and pressure was shown. Neuron blowing by solutions without cAMP gave the similar effect. The effect of cAMP can be differentiated in the presence of phosphodiesterase inhibitors. The experiments support the hypothesis that cyclic nucleotides and mechanical(More)
Cyclic 3',5'-AMP and cyclic 3',5'-GMP injected into large neurons of the snail Helix lucorum altered neuron activity. The effect of cAMP is usually depolarizing and that of cGMP hyperpolarizing. The results are specific for 3',5'-cyclic nucleotides. The experiments support the hypothesis that reaction-diffusion processes involving cyclic nucleotides form(More)
Intracellular microiontoforetic injections of cyclic 3',5'-AMP and cyclic 3',5'-GMP elicit different responses in the same neuron. Drugs were injected by current of 1--10 nA using 3-barrel micropipettes. Unlike cyclic 3',5'-AMP arising the depolarization of the neuron, cyclic 3',5'-GMP usually hyperpolarizes it. An inhibitor of phosphodiesterases,(More)
Investigation of the influence of cAMP on neuronal electric activity suggests that nerve cells can solve problems using an intraneuronal calculating medium based on the cytoskeleton. When a new problem is posed, this structure has to be disassembled and assembled by the neuronal molecular computer according to the program recorded in DNA. If DNA lacks an(More)
The separate fourth intracellular microelectrode was used for controlling the conditions of cyclic nucleotide injection in neurons of Helix pomatia. Ionoforetic increase in intracellular cyclic AMP concentration elicits membrane depolarization in many neurons. Phosphodiesterase inhibitors 3-isobutyl-1-methylxantine and SQ-20009 prolong this depolarization(More)