Olga Castañeda

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A peptide toxin, ShK, that blocks voltage-dependent potassium channels was isolated from the whole body extract of the Caribbean sea anemone Stichodactyla helianthus. It competes with dendrotoxin I and alpha-dendrotoxin for binding to synaptosomal membranes of rat brain, facilities acetylcholine release at an avian neuromuscular junction and suppresses K+(More)
Peptides have been isolated from several species of sea anemones and shown to block currents through various potassium ion channels, particularly in excitable cells. The toxins can be grouped into four structural classes: type 1 with 35-37 amino acid residues and three disulphide bridges; type 2 with 58-59 residues and three disulphide bridges; type 3 with(More)
The potassium channel toxin secreted by the sea anemone Bunodosoma granulifera (BgK) is a 37-amino-acid peptide containing three disulfide bridges. Because a synthetic peptide corresponding to the reported sequence of BgK was found not to fold properly, the sequence was determined again. The new sequence differed from the previous one in the C-terminal(More)
Physalia physalis is a marine cnidarian from which high molecular weight toxins with hemolytic and neurotoxic effects have been isolated. In the present work, two novel toxins, PpV9.4 and PpV19.3 were purified from P. physalis by bioactive guideline isolation. It involved two steps of column chromatography, gel filtration and RP-HPLC. The molecular weights(More)
The current investigation focuses attention on the neuroprotective and antioxidant properties of aqueous extracts from Halimeda incrassata (Hi) and Bryothamniom triquetrum (Bt) in the mouse immortalized hypothalamic GT1-7 cell line. Under basal oxidative conditions, Hi extract reduces intracellular reactive oxygen species production, as assessed by(More)
Epidemiologic studies have emphasized the close relationship between high BP and cardiovascular disease (CVD). Recently published prospective studies have focus on systolic and pulse pressure (PP). Systolic BP seems to be a more important factor than diastolic BP on cardiovascular and all-cause mortality in older patients. PP reflects stiffness of the large(More)
Cnidarians comprise a taxon with a high biodiversity of cytolitic, neurotoxic and cardiotoxic compounds, which have not been studied on insulin release. We tested the effect of a crude extract of Zoanthus sociatus (Ellis, 1767) and the low molecular weight fraction of this extract on insulin secretion in isolated rat β-cells and also in a glucose tolerance(More)
The phylum Cnidaria is an ancient group of venomous animals, specialized in the production and delivery of toxins. Many species belonging to the class Anthozoa have been studied and their venoms often contain a group of peptides, less than 10 kDa, that act upon ion channels. These peptides and their targets interact with high affinity producing neurotoxic(More)
An analysis of 39 Mexican coastal lagoons most in tropical environments, shows no nutrient limitation for primary productivity: even minimum nutrient values are higher than those of similar systems (mostly of temperate zones). In some cases, nutrient variations are large and indicative of heterogeneity. The N:P ratio is more important than simple nutrient(More)