Gaspar Bruner

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ATP stimulates arachidonic acid mobilization and eicosanoid production in cultured astrocytes via P2Y-purinergic receptors. To assist in determining the mechanism of phospholipase A2 activation and the role of calcium in eicosanoid production, cultures were pretreated with pertussis toxin (PTx). ATP-evoked eicosanoid release was inhibited by PTx in a(More)
To reveal more of the mechanism whereby ATP induces arachidonic acid (AA) mobilization in astrocytes, primary cell cultures prelabeled with [3H]AA were exposed to ATP and various analogs. Release of 3H was dose and time dependent and was inhibited by blocking ATP binding. The potencies of a range of ATP analogs in mobilizing AA were consistent with that(More)
In astrocytes, a number of second messenger systems are activated upon stimulation with ATP. Recently, UTP has been demonstrated to have effects similar to ATP in some cell types. To determine if this was also true in astrocytes, cultured cells were stimulated with UTP which was found to evoke thromboxane release, stimulate inositol phospholipid turnover(More)
Multipartner mutualisms have potentially complex dynamics, with compensatory responses when one partner is lost or relegated to a minor role. Fungus-growing ants (Attini) are mutualistic associates of basidiomycete fungi and antibiotic-producing actinomycete bacteria; the former are attacked by specialized fungi (Escovopsis) and diverse generalist microbes.(More)
We used a simple engineering principle, which suggests that the width of a road needed for a smooth traffic flow is proportional to the peak traffic volume (“engineering hypothesis”), to analyze the adaptive significance of trail width at branching points in the leaf-cutting ant Atta cephalotes. Since the flow of outgoing ants splits at trail bifurcations(More)
Ant social parasites evolve adaptive relationships with their hosts. Theoretically, coevolution predicts strong selection to maximize fitness of the parasite that minimizes costs to its host, which potentially leads to the evolution of benign interactions. We studied the demographic and behavioral traits of the ant social parasite Megalomyrmex symmetochus(More)
To assess the contribution of phospholipase D to agonist-evoked arachidonic acid mobilization in central nervous system astroglial cells, enzyme activity was determined by formation of phosphatidylethanol. Phosphatidylethanol was formed upon stimulation of the cells with phorbol esters and also ionomycin and thapsigargin, agents which increase intracellular(More)
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