Jassim M. Al-Hassan

Composition of the proteinaceous gel secretion from the skin of the Arabian Gulf catfish (Arius thallasinus)

The Arabian Gulf catfish Arius thallasinus excretes copious amounts of proteinaceous gel from epidermal cells when threatened or injured. As a means of investigating its biological role, this gel material has been examined to determine the nature of the secretion and its associated biological activities. Over 85% of the dry weight of the gel material is protein with small amounts of lipids, carbohydrates and nucleic acid components. Most of the protein exists as a high molecular weight aggregate of predominantly 13 500 molecular weight monomeric units. Several lytic enzyme activities are found in the gel secretion, one of which catalyzes lysis of red blood cells. Other factors induce clotting in citrate treated plasma and agglutination of red blood cells. The enzymic properties of the gel secretion resemble those of some animal venoms.

Antithrombotic activity of garlic: its inhibition of the synthesis of thromboxane-B2 during infusion of arachidonic acid and collagen in rabbits.

Rabbits were given collagen and arachidonic acid intravenously. Blood pressure, platelet counts, plasma thromboxane-B2 (TXB2) and plasma 6-keto-prostaglandin F1 alpha, (6-keto-PGF1 alpha) were determined. Both thrombogenic agents, upon infusion of a lethal dose, caused thrombocytopenia, indicative of in vivo platelet aggregation and hypotension. These changes were associated with an increase in plasma levels of TXB2 and 6-keto-PGF1 alpha measured by radioimmunoassay (RIA). Pretreatment of rabbits with an aqueous extract of garlic (500 mgkg) provided protection from thrombocytopenia and hypotension. Thromboxane-B2 synthesis was significantly reduced in animals pretreated with garlic and then injected with a lethal dose of either collagen or arachidonic acid. The amount of TXB2 synthesized in these animals was not sufficient to induce thrombocytopenia or hypotension. All animals pretreated with garlic were well protected against the effects of collagen or arachidonate infusion, and no apparent symptoms were observed in these animals. These observations indicate that garlic may be beneficial in the prevention of thrombosis.

Catfish epidermal secretions in response to threat or injury

The Arabian Gulf catfish (Arius thalassinus, Rüppell) secrete a thick layer of proteinaceous material when threatened or injured. The chemical and pharmacological properties of this material indicate that it may promote the healing of wounds. These studies suggest that the abrupt secretion of mucous-like gel in response to a perceived hazard is an externally expressed defense response; the secretion may have a primary function in healing injury beyond the commonly postulated roles of deterring predators or facilitating escape.

Purification and properties of a hemagglutination factor from Arabian Gulf catfish (Arius thalassinus) epidermal secretion

A galactose specific lectin was isolated from an epidermal proteinaceous gel secretion of the Arabian Gulf catfish, Arius thalassinus, Ruppell. The lectin was extracted and purified to near homogeneity by exclusion chromatography, affinity chromatography and isoelectric focusing. The lectin appears to be active as a single polypeptide chain with a mol. wt near 200,000, which can form oligomers and heteropolymers. The lectin comprises about 2% of the total gel protein, lacks carbohydrates and contains no unusual types or amounts of amino acids. The lectin agglutinates a wide range of red blood cell types.

Toxic and Pharmacologically Active Secretions from the Arabian Gulf Catfish (Arius Thalassinus, Ruppell)

AbstractArabian Gulf catfish (Arius thalassinus Ruppell) (38), secrete venom from a gland at the base of each pectoral spine, and also elaborate a thick proteinaceous gel-like material from epidermal cells when the fish are threatened or injured. Both of these secretions contain a complex mixture of components which have potent pharmacological effects on test animals. The venom has been thought to play a defensive function in fish survival, but the epidermal secretion does not appear to play a similar active role in predator defense.Both secretions have components with “typical” venom hemolytic and hemotoxic activities. These are not present at levels high enough to cause lethal responses in test animals when injected at levels commonly associated with injuries caused by catfish spines. However, the epidermal secretion contains additional novel protein and lipid constituents, previously unreported in venomous secretions, which confer a lethal activity to this material when it is injected intravenously int...

Vasoconstrictor components in the Arabian Gulf catfish (Arius thalassinus, Ruppell) proteinaceous skin secretion.

The Arabian Gulf catfish (Arius thalassinus, Ruppell) produces toxic substances from its skin and from venom glands located near the base of the pectoral fins. Investigation of the pharmacological properties of the skin toxin have previously shown cholinergic vasoconstrictor activity in umbilical arteries. Cholinergic vasoconstriction was confirmed in sheep renal arteries. This activity was partially blocked by atropine, while most of the residual contraction was eliminated by simultaneous addition of indomethacin. Skin toxin treatment of arterial specimens caused a release of prostaglandin (PGE2, TXB2 and 6-keto-PGF1 alpha) into the organ bath. Prostaglandin release was blocked by pretreatment with indomethacin. Heat denaturation of skin toxin caused a loss of only the indomethacin-sensitive muscle contraction activity; most of the residual activity was blocked by atropine.

Toxic effects of the soluble skin secretion from the Arabian Gulf catfish (Arius thallasinus, Ruppell) on plasma and liver enzyme levels

Injection of skin toxin into the marginal ear vein of rabbits resulted in acute respiratory distress and convulsive movements, followed by death within 7 min. Significant increases in total plasma lactate dehydrogenase and the hepatic and cardiac derived isozymes and in glutamic-oxaloacetic and glutamic-pyruvic transaminase activities were observed in animals receiving toxin. Lower doses of toxin increase the survival time and enzyme levels in plasma. Skin toxin produces a time dependent toxic effect on the liver and heart.

Protein composition of the threat induced epidermal secretion from the Arabian Gulf catfish, Arius Thalassinus (Ruppell)

1. When threatened or injured, the Arabian Gulf catfish (Arius thalassinus, Ruppell) secretes a thick gel-like layer of proteinaceous material to its skin surface mainly from unicellular glands of the epidermis termed club cells. 2. Since a preparation from this secretion has been implicated in stimulation of the rate of wound healing in man and other test animals, the total gel protein composition was analysed by chemical, chromatographic and electrophoretic techniques. 3. Gel proteins were separated into soluble and insoluble fractions by extractions with increasingly strong solubilizing agents and the most insoluble components were solubilized only upon treatment with 10% SDS or concentrated organic acids. 4. Some of the soluble proteins from the secretion are also present in the insoluble protein fractions, indicating that the insoluble material is formed in part by aggregation of the soluble proteins. 5. The secretion was shown to be distinct from the catfish venom and differed greatly from typical fish mucus secretions in its composition and distribution of protein components.

Vascular responses elicited by venom of Arabian catfish (Arius thallasinus)

The Arabian catfish produces venoms from the skin (SV) and glands near the pectoral spines (GV). 1. The venoms have a high protein concentration, only limited amounts of lipid, carbohydrate and nucleic acid. Enzyme activities included alkaline phosphatase and esterases. Both SV and GV induce hemolysis. 2. SV and GV induced a dose-dependent smooth muscle contraction of human umbilical artery preparations. This response was competitively inhibited by atropine, suggesting a cholinergic response. 3. Heat treatment of GV did not decrease activity, while heating SV reduced it. 4. In-vivo experiments showed mainly a depressor response in rat and guinea-pig.

Prostaglandin associated mortality following intravenous injection of catfish epidermal secretions in rabbits

Toxicity of soluble protein extracts from epidermal gel secretions of the catfish, Arius thalassinus, was examined in rabbits. Intravenous injections containing doses as low as 2 mg protein/kg body weight caused mortality in all animals tested. An increase in plasma levels of thromboxane B2 (TXB2) and of 6-keto prostaglandin F1 alpha (6-keto PGF1 alpha) were observed following injections. Both the mortality and prostaglandin release were prevented by pretreatment of rabbits with either indomethacin or hydrocortisone. A similar indomethacin sensitive induction of prostaglandin release was noted following the in vitro treatment of arterial tissue sections with gel. Lethality appears to result from gel substances stimulating phospholipase activity to yield arachidonic acid, which is then metabolized to give toxic levels of prostaglandins.