Search results for "Marine Toxin"

Cycloamphilectenes, a new type of potent marine diterpenes: inhibition of nitric oxide production in murine macrophages.

2003

The inhibitory effect of a series of 6 cycloamphilectenes, novel marine diterpenes based on amphilectene skeletons and isolated from the Vanuatu sponge Axinella sp., on NO, PGE(2) and TNFalpha production in murine peritoneal macrophages was studied. These compounds reduced potently nitric oxide production in a concentration-dependent manner with IC(50) values in the submicromolar range (0.1-4.3 microM). Studies on intact cells and Western blot analysis showed that the more potent cycloamphilectenes reduced the expression of inducible nitric oxide synthase without affecting cyclo-oxygenase-2 expression. Among them cycloamphilectene 2, the unique compound bearing an exocyclic methylene group,…

Novel Analogs and Stereoisomers of the Marine Toxin Neodysiherbaine with Specificity for Kainate Receptors

2007

Antagonists for kainate receptors (KARs), a family of glutamategated ion channels, are efficacious in a number of animal models of neuropathologies, including epilepsy, migraine pain, and anxiety. To produce molecules with novel selectivities for kainate receptors, we generated three sets of analogs related to the natural marine convulsant neodysiherbaine (neoDH), and we characterized their pharmacological profiles. Radioligand displacement assays with recombinant alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and KARs demonstrated that functional groups at two positions on the neoDH molecule are critical pharmacological determinants; only binding to the glutamate receptor …

Dinoflagellates from marine algal blooms produce neurotoxic compounds: effects on free calcium levels in neuronal cells and synaptosomes

2000

In this report, evidence is presented that the marine unicellular eukaryotic dinoflagellates can cause neurotoxicity very likely by an increase in intracellular free calcium ions ([Ca(2+)](i)). Determinations of the effects of culture supernatants from different clones of the dinoflagellate Alexandrium sp. isolated from algal blooms on the viability of rat primary neuronal cells revealed that all clones tested were toxic for these cells. In addition, all Alexandrium clones tested, except for A. ostenfeldii BAH ME-141, were found to be toxic for rat pheochromocytoma PC12 cells. No toxicity was observed for culture supernatants from Gonyaulax and Coolia monotis. Calcium ions are important in …

Minireview: Nicotinic Acetylcholine Receptors on Hippocampal Neurons: Distribution on the Neuronal Surface and Modulation of Receptor Activity

1997

The recent development of a technique that uses infrared microscopy for the visualization of well-defined areas on the surface of neurons, and a computerized system of micromanipulators led to the discovery that functional nicotinic acetylcholine receptors (nAChRs) are expressed at higher density on the dendrites than on the soma of rat hippocampal neurons. The finding that the expression of alpha-bungarotoxin-sensitive, alpha 7-bearing, nAChRs and dihydro-beta-erythroidine-sensitive, alpha 4 beta 2 nAChRs tends to increase along the dendritic length suggests that these receptors may be highly involved in the integration of synaptic functions in hippocampal neurons. The present report also …

Inhibition of B2 receptor internalization delays its dephosphorylation

1997

Focal adhesions are hotspots for keratin filament precursor formation

2006

Recent studies showed that keratin filament (KF) formation originates primarily from sites close to the actin-rich cell cortex. To further characterize these sites, we performed multicolor fluorescence imaging of living cells and found drastically increased KF assembly in regions of elevated actin turnover, i.e., in lamellipodia. Abundant KF precursors (KFPs) appeared within these areas at the distal tips of actin stress fibers, moving alongside the stress fibers until their integration into the peripheral KF network. The earliest KFPs were detected next to actin-anchoring focal adhesions (FAs) and were only seen after the establishment of FAs in emerging lamellipodia. Tight spatiotemporal …

Changes of ICE protease activities caused by toxic supernatants of dinoflagellates (Prorocentrum species) from marine algal blooms

1999

Summary Marine phytotoxins may become a major health problem for humans because of their ability to contaminate seafood and to cause shellfish poisoning. In this report, the cytotoxic effects and the effects on intracellular caspase activities of culture supernatants from different dinoflagellate Prorocentrum clones were determined. Among the clones tested, P. tepsium BAH ME-140 and P. lima BAH ME-130 K1 and K2 clones but not P. minimum and P. micans were found to be toxic on rat pheochromocytoma PC12 cells, mouse lymphoma L5178Y cells and rat primary neurons. A significant increase in the specific activities of caspase 1 (ICE), caspase 3 (CPP32) and caspase 6 (Mch2) to 149–167% was observe…

Potentiation of the cytotoxic activity of copper by polyphosphate on biofilm-producing bacteria: A bioinspired approach

2012

Adhesion and accumulation of organic molecules represent an ecologically and economically massive problem. Adhesion of organic molecules is followed by microorganisms, unicellular organisms and plants together with their secreted soluble and structure-associated byproducts, which damage unprotected surfaces of submerged marine structures, including ship hulls and heat exchangers of power plants. This is termed biofouling. The search for less toxic anti-biofilm strategies has intensified since the ban of efficient and cost-effective anti-fouling paints, enriched with the organotin compound tributyltin, not least because of our finding of the ubiquitous toxic/pro-apoptotic effects displayed b…