Specific blockage of squid axon resting potassium permeability by Haliclona viridis (Porifera: Haliclonidae) toxin (HvTX).

The action of partially purified HvTX, toxin of the marine sponge H. viridis, was explored on the giant axon of the tropical squids Doryteuthis plei and Sepioteuthis sepioidea. HvTX depolarizes the nerves dose dependently. The effect occurs after blocking sodium channels with tetrodoxin (1 microM), removing external Na+, blocking electrically excitable K+ channels with 3,4-diaminopyridine (10 mM) or internal and external application of tetraethylammonium (40 mM). Ouabain (up to 10 mM) does not modify HvTX effect. The action of HvTX occurs only when it is applied to the outer phase of the nerve membrane; microinjection of the toxin into the axons lacks depolarizing effects. HvTX reduces the dependence of membrane potential on external potassium concentration. The apparent 86Rb+ permeability (pi') was measured in axons of S. sepioidea. The value of pi' in normal artificial sea water was 80 (61,96) nm/sec (median and its 95% confidence interval, n = 8) and raised to 1030 (588, 2113) nm/sec (n = 7) when the axons were depolarized to 0 mV raising external K+ to 300 mM. In axons depolarized with HvTX (10 mM external K+) to 0 mV, pi' was 88 (55, 97) nm/sec (n = 8). HvTX could not prevent (P >> 0.05) the increase in pi' induced by 300 mM K+ when the ion concentration was raised before toxin application [pi' = 660 (354, 1876) nm/sec, n = 7]. Most of the 86Rb+ permeability increase in high K+ was prevented if HvTX was added before external K+ was raised [pi' = 298 (264, 337) nm/sec, n = 8]. All the measures of pi' were carried out in solutions containing 1 microM tetrodotoxin, 1 mM 3,4-diaminopyridine and 2 mM ouabain.

Toxicology of a bovine paraplegic syndrome.

A clinical entity named 'bovine paraplegic syndrome' ('síndrome parapléjico de los bovinos') has spread alarmingly in the cattle-growing areas of the central and eastern plains of Venezuela. It is estimated that four million cattle are bred in the area where the disease occurs. The mortality ranges from 5 to 25% of the animals at risk, mostly pregnant or lactating cows. The principal characteristic of the bovine paraplegic syndrome is ventral or sternal decubitus, in animals that make vain efforts to stand when stimulated. The diagnosis is established when all other possible causes (e.g. paralytic rabies, botulism and blood parasites such as Anaplasma marginal, Babesia bovis, B. bigemina, and Trypanosoma vivax) have been ruled out clinically and by laboratory tests. Death always occurs, usually after a few days, and there is no known treatment. In this work, we describe results that show the presence of a toxin in the cattle suffering from, or liable to suffer from the syndrome. The toxin is produced by ruminal bacteria. In squid giant axons under voltage clamp conditions, the toxin blocks the sodium current. We detected the toxin analytically by absorbance measurements at 340 nm after reacting with picrylsulfonic acid. We obtained a good separation of the toxin with isocratic high pressure liquid chromatography, using 40% methanol in water on phenylborasil columns.

[Toxinology of bovine paraplegic syndrome]. / Estudio sobre la toxinología del síndrome parapléjico de los bovinos.

A clinical entity named "Bovine Paraplegic Syndrome" ("Síndrome Parapléjico de los Bovinos") has spread alarmingly, in the cattle growing areas of the central and eastern plains of Venezuela. Approximately four million cattle are bread in the area were the disease occurs. The mortality index due to the disease ranges 5 to 25% of the animals at risk, mostly cows, pregnant or lactating. The principal characteristic of the bovine paraplegic syndrome is decubitus, ventral or sternal, in animals that make vane efforts to stand when stimulated. The diagnosis is established ruling out, clinically and with laboratory findings, that the animals are suffering known diseases with similar symptoms such as paralytic rabies, botulism and blood parasites such Trypanosoma sp., Babesia sp., and Anaplasma sp.. Death occurs always, usually after few days, and to this date there is no known treatment able to save the sick cows. In this work, we describe results that suggest the presence of a toxin in the cattle suffering and prone to suffer the syndrome; it is a natural toxin produced by ruminal bacteria. In squid giant axons under voltage clamp conditions, this toxin is very specific to block sodium current during nerve electrical activity.

Methods for correlation analysis of toxins and species present in random samples of phytoplankton.

We developed and tested two new procedures to find which species present in samples of phytoplankton is responsible for the production of a toxin. The procedures represent a different form of correlation analysis that uses information on the presence or absence of the toxin, and on the relative abundance of each species of plankton in the samples. The efficiency of the algorithms is tested by random process simulation. The algorithms were clearly superior to known techniques dealing with correlations between binary variables to show the toxin producing microorganism. We used experimental toxin isolation from phytoplankton as an example of practical success using the most efficient of the algorithms tested.

Ichthyotoxism by a paralytic toxin produced by marine dinoflagellates of the genus Ceratium: relationship to fraction beta isolated from the sponge Tedania ignis.

Two hundred tons of the plankton feeding sardine Cetengraulis edentulus died in March 1982, in Carenero (10 degrees 10' N, 66 degrees 05' W), Venezuela. A fraction was extracted from this fish that was toxic to mice by i.p. injection. The animals died in less than 4 min and showed generalized flaccid paralysis. Gel filtration on Sephadex G15 and Bio Gel P2 showed that the toxicity is related to a fraction that blocks the release of acetylcholine in frog (Rana pipiens) neuromuscular junctions. This toxin is similar in chemical properties and presynaptic effect to fraction beta isolated from the sponge T. ignis by Sevcik and Barboza. Fractions of the same biological action and chemical properties were isolated from plankton samples collected in the area of the ichthyotoxism. The correlation analysis between the presence of toxin and a plankton species in a sample, was carried out with a feasibility index (as %) defined by Sevcik and Mijares. Random samples of plankton (29) were collected in 3 locations (11 degrees 50' N, 68 degrees 15' W; 10 degrees 36' 24'' N, 67 degrees 14'7'' W and 10 degrees 21' N, 64 degrees 21' W). The correlation carried out over 167 species of phytoplankton present in the samples indicates that the species most likely to be responsible for the production of the fraction beta, in order of feasibility index (in parentheses) are: Ceratium furca (54%), Protoperidinium sp. (1.7%) and Protoperidinium pallidum (1.6%). In some samples a fraction similar to fraction alpha from T. ignis was also found. The identification of the phytoplankton responsible for this fraction is, however, less conclusive. The feasibility indexes are: Protoperidinium sp. (58%), Ceratium inflatum (30%), Podolampas sp. (23%), Ornithocercus steini (21%). The genus Ceratium was the second most abundant in Carenero at the time of the fish death. These results suggest that the toxins isolated from C. edentulus and T. ignis have a planktonic origin.