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PubMed1999

Ultrastructure of Myxidium trachinorum sp. nov. from the gallbladder of the lesser weever fish Echiichthys vipera.

Myxidium trachinorum sp. nov. is described from the gallbladder of the lesser weever fish Echiichthys vipera. Pseudoplasmodia attach themselves to the gallbladder epithelium by filose processes, which are inserted between host cells. Pseudoplasmodia undergo endogenous cell formation at the secondary and tertiary levels. In the proliferative cycle, primary and endogenous cells are packed with digestive vacuoles formed by phagocytosis. In the sporogonic cycle the pseudoplasmodium becomes a pericyte enclosing two secondary cells (lacking digestive vacuoles) in a vacuole. These give rise to five cells each two valvogenic, two capsulogenic and a binucleate sporoplasm, which mature into spores. Comparison of the disporic M. trachinorum with polysporic species of Myxidium revealed significant differences in plasmodial ultrastructure, especially their attachments to host cells, surface characteristics and mode of nutrition, and in formation of generative cells. These suggest that the genus Myxidium may require revision.

Animals↗
PubMed1984

Biphasic effect on platelet aggregation by phospholipase a purified from Vipera russellii snake venom.

A basic phospholipase A was isolated from Vipera russellii snake venom. It induced a biphasic effect on washed rabbit platelets suspended in Tyrode's solution. The first phase was a reversible aggregation which was dependent on stirring and extracellular calcium. The second phase was an inhibitory effect on platelet aggregation, occurring 5 min after the addition of the venom phospholipase A without stirring or after a recovery from the reversible aggregation. The aggregating phase could be inhibited by indomethacin, tetracaine, papaverine, creatine phosphate/creatine phosphokinase, mepacrine, verapamil, sodium nitroprusside, prostaglandin E1 or bovine serum albumin. The venom phospholipase A released free fatty acids from synthetic phosphatidylcholine and intact platelets. p-Bromophenacyl bromide-modified venom phospholipase A lost its phospholipase A enzymatic and platelet-aggregating activities, but protected platelets from the aggregation induced by the native enzyme. The second phase of the venom phospholipase A action showed a different degree of inhibition on platelet aggregation induced by some activators in following order: arachidonic acid greater than collagen greater than thrombin greater than ionophore A23187. The longer the incubation time or the higher the concentration of the venom phospholipase A, the more pronounced was the inhibitory effect. The venom phospholipase A did not affect the thrombin-induced release reaction which was caused by intracellular Ca2+ mobilization in the presence of EDTA, but inhibited collagen-induced release reaction which was caused by Ca2+ influx from extracellular medium. The inhibitory effect of the venom phospholipase A and also lysophosphatidylcholine or arachidonic acid could be antagonized or reversed by bovine serum albumin. It was concluded that the first stimulatory phase of the venom phospholipase A action might be due to arachidonate liberation from platelet membrane. The second phase of inhibition of platelet aggregation and the release of ATP might be due to the inhibitory action of the split products produced by this venom phospholipase A.

Adenosine Triphosphate↗
PubMed1976

A phospholipase A2 with anticoagulant activity. I. Isolation from Vipera berus venom and properties.

An anticoagulant protein has been isolated by DEAE cellulose chromatography and gel filtration from the venom of the Vipera berus orientale (Eastern Europe). Purification has been completed by elution on carboxymethyl cellulose with continuous gradient at constant pH. The inhibitor of coagulation was separated from the other venom enzymes, e.g. procoagulant, fibrinogenolytic, aminoesterase and amino acid oxidase activities. It was also separated from other phospholipase components which were not related to the anticoagulant property. The inhibitor appeared as a simgle polypeptidic chain protein, formed by 119 amino acid residues, with a molecular weight of 13400 and an isoelectric point of 9.2. At low saline molarity, a monomer-trimer transition of this protein was observed. Both forms had the same amino acid composition. There were six disulfide bridges without free SH groups per phospholipase molecule. Deprived of any proteolytic activity, the clotting inhibitor displayed a high phospholipase activity in the presence of calcium. Activity did no appear with EDTA buffer deprived of cation. Finely dispersed micellar suspensions were found suitable for obtaining the highest phospholipase activity. High sodium cholate concentration or methanol/chloroform/ether solvent were effective without loss of enzymatic activity. As characteristis of phospholipase A2 (EC 3.1.1.4), the degradation products identified on thin-layer chromatography induced hemolysis of human erythrocytes. The apparent Km value 1.25 - 10(-3) M was determined on phosphatidylcholine isolated from ovolecithin. This purified berus inhibitor would be of value for investigating the involvement of phospholipids in the clotting mechanism.

Amino Acids↗
PubMed1985

Relaxant effect of phospholipase A2 from Vipera russelli snake venom on rat aorta.

The effect of the acidic phospholipase A2 (PLA2) from Vipera russelli venom on the rat aortic ring was studied and compared with that of acetylcholine (ACh). PLA2 induced relaxation of the aortic ring precontracted with noradrenaline (NA) in a dose-dependent manner. Removal of the endothelium did not reduce the relaxant effect of PLA2. Replacement of Ca2+ by Sr2+ in the medium to inhibit the PLA2 enzyme activity reduced the relaxant effect. Atropine, a muscarinic receptor antagonist, did not affect the relaxant response. The cyclooxygenase inhibitor indomethacin, when equilibrated for 50 min, potentiated the relaxation. The lipoxygenase inhibitor nordihydroguaiaretic acid (NDGA) partially reduced the relaxation. This relaxation was also partially reduced by the guanylate cyclase inhibitor methylene blue. In contrast, the relaxation elicited by ACh was abolished by de-endothelialization, atropine, NDGA or methylene blue. 6-keto-PGF1 alpha (degradation product of prostacyclin) and PGE2 produced by aortic rings were measured by radioimmunoassay. PLA2 (3 X 10(-6) g/ml) increased the output of 6-keto-PGF1 alpha about 10-fold. The production of PGE2 was also increased but to a lesser extent. ACh also increased the output of 6-keto-PGF1 alpha and PGE2. However, prostacyclin released by PLA2 and ACh appears not to contribute to the relaxant effect, since prostacyclin does not relax the rat aorta. It is concluded that the relaxation elicited by PLA2 in the rat aorta is endothelium-independent and partially mediated by lipoxygenase product(s) and cyclic GMP whereas the relaxation induced by ACh was endothelium-dependent, mediated by lipoxygenase product(s) and cyclic GMP, and blocked by atropine.

Acetylcholine↗
PubMed1990

Evolutionary specificity of hydrins, new hydroosmotic neuropeptides: occurrence of hydrin 2 (vasotocinyl-Gly) in the toad Bufo marinus but not in the viper Vipera aspis.

Hydrin 2 (vasotocinyl-Gly), a hydroosmotic peptide resulting from differential processing of provasotocin and recently identified in frog neurohypophysis, has been looked for in the pituitary gland of an exotic toad (Bufo marinus) and of a reptile (Vipera aspis). Hydrin 2 has been found in the amphibian but not in the reptile. This result confirms the evolutionary specificity of hydrin 2 that has been identified only in frogs and toads but not in birds and reptiles. Occurrence of hydrin 2 is explained by its regulatory function on the water permeability of the skin of anurans.

Animals↗
PubMed1996

Novel anti-platelet aggregation polypeptides from Vipera lebetina venom: isolation and characterization.

Lebetins 1 and Lebetins 2, two polypeptide groups that inhibit platelet aggregation, were isolated from Vipera lebetina venom by gel filtration and reverse phase chromatography. Amino acid sequencing indicated that the first group contains two major polypeptides of 13 and 12 residues; their molecular weight was determined by electrospray mass spectrometry. The second was composed of two peptides of 38 and 37 residues, each with one disulfide bond. Sequence analysis revealed neither RGD sequence nor homology with other proteins including known snake or tick polypeptides. Lebetins 1 were Pro and Lys rich peptides and their sequences were identical to the N-terminus of Lebetins 2. Lebetins inhibited platelet aggregation induced by thrombin, collagen and PAF-acether. The 50% concentration that inhibited human and rabbit platelet aggregation induced by thrombin was 590 nM and 125 nM for Lebetins 1 and 100 nM and 8 nM for Lebetins 2, respectively. Lebetins 1 and Lebetins 2 also inhibited fibrinogen-induced aggregation of alpha-chymotrypsin-treated platelets as well as in vivo collagen-induced thrombocytopenia in rats with half effective doses of 2 nmol/kg and 4.2 nmol/kg, respectively. Lebetins were not toxic after intravenous injection into mice and rats. These polypeptides form novel platelet inhibitors that could be used to delineate further the mechanisms of platelet aggregation and serve as a model for developing antithrombotic agents.

Amino Acid Sequence↗
PubMed1987

[Relations between hibernation and the resumption of endocrine, testicular and thyroid activities, in Vipera aspis L. (Reptilia, Viperidae)].

The relationships between the end of hibernation and testicular and thyroid endocrine recrudescence were tested in Vipera aspis by subjecting hibernating vipers to experimental climatic conditions. Vipers kept under artificially warmed conditions (for 3.5 hr during the day to a thermal gradient from 11 to 27 degrees) 1 month before emergence showed an increase in plasma testosterone before vipers exposed to natural conditions (outdoor enclosures) did. The use of different photoperiodic conditions, long, LD 12:12, and short, LD 8:16, shows that photoperiod length has no effect on this increase. For vipers kept under prolonged hibernation (under a uniform temperature of 5 degrees or exposed to natural conditions at the northern limit of the species' distribution), testicular endocrine recrudescence was observed as soon as the first emergence only for the vipers placed at the northern range limit. Whatever the conditions, experimental or natural, the emergence of vipers always corresponds to a weight loss correlated with the increase of plasma thyroxine level. The relationship between the end of hibernation and testicular and thyroid endocrine recrudescence is discussed.

Animals↗
PubMed1987

Osmotic stress, plasma renin activity, and spermatogenesis in Vipera aspis.

Circulating electrolytes (Na+, K+), plasma renin-like activity, testosterone, and testis morphology were investigated in early summer during the spermatogenic progressive phase in Vipera aspis subjected to sodium loading and sodium depletion. After sodium loading, plasma sodium and plasma testosterone levels were significantly elevated compared with those of controls, while plasma renin-like activity was depressed, spermiogenesis was increased, the epithelium lining the epididymis was very thick, and the Leydig cells were hypertrophied. After sodium depletion, plasma sodium and plasma testosterone levels were significantly depressed and plasma renin-like activity was significantly elevated. Spermiogenesis seemed to be slightly regressed: the epithelium lining the epididymis was very thin, and the lumen was devoid of spermatozoa. The Leydig cells were hardly visible. All the data strongly suggest that osmotic stress affects gonadal activity in the snake. V. aspis.

Animals↗
PubMed1987

Annual cycles in plasma testosterone and thyroxine in the male aspic viper Vipera aspis L., (Reptilia, Viperidae), in relation to the sexual cycle and hibernation.

Blood samples were taken monthly from males of Vipera aspis kept in outdoor terraria. Plasma testosterone was estimated by radioimmunoassay and plasma thyroxine by the technique of isotopic competition, between October 1979 and September 1985. Plasma testosterone showed an annual bimodal profile. The highest peak was observed from February 15 to the end of March. 2 to 5 weeks after the first emergence from hibernation. Values then decreased greatly, to reach a minimum level when the vernal spermiogenesis was at its maximum. The secondary peak of plasma testosterone was lower and less well marked. It occurred at the end of summer, during the strongest spermiogenesis, and preceded the autumnal facultative mating period. Plasma thyroxine was at a maximum concentration from February to March after which levels decreased markedly. The seasonal profile of plasma thyroxine was clearly marked during the period of hibernation. From September to October, 2 months before the beginning of hibernation, thyroxine levels began to decrease, and they reached a minimum in November-December. Endocrine reactivation of the thyroid appeared at the end of hibernation. However, in contrast to the plasma testosterone, endocrine activity of the thyroid began 2 to 3 weeks before the end of hibernation. Mechanisms of reactivation for testicular and thyroidal endocrine structures are discussed.

Animals↗
PubMed1990

Changes in plasma progesterone in female Vipera aspis L. (Reptilia, Viperidae) during the sexual cycle in pregnant and nonpregnant females.

The plasma progesterone concentration in female Vipera aspis changes during pregnancy and exhibits an increase before ovulation, a summer peak, a decrease up to parturition, and a new increase at the beginning of hibernation. For females in their first or second year after gestation, the evolution of plasma progesterone shows a spring peak and a summer peak. Whatever the stage of the sexual cycle, females present two annual periods of steroidogenic activity producing plasma progesterone: one in spring and one in summer. All data suggest an annual endogenous endocrinological cycle of reproduction, modulated by external factors (temperature, food availability). The origin of plasma progesterone and its control in the sexual cycle are discussed.

Animals↗
PubMed1990

Characterization of a new inhibitor for angiotensin converting enzyme from the venom of Vipera aspis aspis.

1. Angiotensin converting enzyme inhibitor has been isolated from the venom of Vipera aspis aspis by gel filtration and reverse phase HPLC. 2. The purified inhibitor is a decapeptide, whose amino-terminal is blocked, with mol. wt 1044 determined by fast atom bombardment mass spectrometry. 3. The peptide inhibited the conversion of angiotensin I to angiotensin II, and Ki values were determined to be 7.54 x 10(-4) and 1.36 x 10(-4) M, respectively, using Hip-His-Leu and Hip-Gly-Gly as substrates 4. The peptide also inhibited the degradation of bradykinin, induced hypotension in spontaneously hypertensive rats and caused an increase in capillary permeability in rabbits, however, it possessed no lethality.

Amino Acid Sequence↗
PubMed1990

Isolation and characterization of factor X activator from the venom of Vipera aspis aspis.

1. A factor X activator was isolated from the venom of Vipera aspis aspis (Aspic viper) by gel filtration and ion-exchange chromatography. 2. The purified activator has a mol. wt of 75,000 and an isoelectric point of 4.6. Upon reduction, this activator migrated as two bands with mol. wts of 16,000 and 14,000 in sodium dodecyl sulfate polyacrylamide gel electrophoresis. 3. The activator from V. a. aspis venom shortened activated partial thromboplastin time (APTT) of normal plasma and factor IX-deficient plasma from humans. 4. Factor X incubated with isolated activator and calcium ions drastically shortened APTT of factor X-deficient plasma and expressed hydrolytic activity against synthetic substrates for factor Xa, however no hydrolytic activity was detected with the activator alone, indicating that the activator converted factor X to the active form.

Amino Acid Sequence↗
PubMed1993

Isolation and characterization of procoagulant from the venom of Vipera aspis aspis.

1. A procoagulant protein was isolated from Vipera aspis aspis (Aspic viper) venom by Sephadex G-75, DEAE-Sephacel, Q-Sepharose and Sephadex G-150 column chromatography. 2. The purified protein has a molecular weight of 125,000 and an isoelectric point of 4.3. 3. This procoagulant decreased the clotting time of plasma from humans, however, direct fibrongen clotting activity was not detected. 4. Diisopropyl fluorophosphate, a serine-protease inhibitor affected coagulant activity of purified protein significantly, while a factor Xa inhibitor (3-ABPE) possessed a slight inhibitory effect. 5. Bovine prothrombin incubated with isolated protein, phospholipid emulsion, bovine factor V and calcium ions drastically decreased the clotting time of fibrinogen and expressed hydrolytic activity against synthetic arginine esterase substrates. However, no hydrolytic activity these substrates was detected with the procoagulant alone indicating that this protein might participate in activation of prothrombin.

Amino Acid Sequence↗
PubMed1994

Purification, characterization and biological activities of phospholipase A from Russell's viper (Vipera russelli) venom.

1. The major phospholipase A has been purified to electrophoretic homogeneity from the venom of Vipera russelli (Russell's viper). 2. The molecular weight of the purified enzyme was estimated to be 31,000 by Sephadex G-75 gel filtration chromatography and 29,000 by SDS-polyacrylamide gel electrophoresis. The enzyme exhibited an apparent Km value of 2.3 x 10(-2) M. 3. The phospholipase A showed edema forming, indirect hemolytic and myonecrotic activities but not hemorrhagic activity.

Animals↗
PubMed1982

Distribution of vipera ammodytes toxic phospholipase A in the cat and its ability to cross the blood-brain barrier.

Several phospholipases A could be isolated from the venom of the European viper, Vipera ammodytes, having different specific activities toward egg lecithin and different lethalities. The most lethal of these enzymes is fraction "k2" having an intravenous LD50 for white mice of 0.021 mg per kg and a specific activity of 280 microM/min mg at 40 degrees C. The enzyme could be labeled with 131I without loosing its enzymatic activity and lethality. The passage of this enzyme from blood into cerebrospinal fluid (CSF) was followed in anesthetized cats. Approximately 1% of the blood level of the enzyme was found in CSF indicating the ability of this protein to penetrate the blood-brain barrier. Although the lethality of fraction "k2" becomes as low as 0.085 microgram/kg when applied intraventricularly, it is not very likely that the central effects of this fraction are of major importance in envenomation since the distribution pattern of the labeled enzyme shows that most of the protein remains in liver, lungs and kidneys, presumably non-selectively bound to membranes and only 0.2% of the injected fraction can reach the brain. Relatively high amount of enzyme was also found in the diaphragm. The penetration of the blood-brain barrier of the radiolabeled phospholipase is within the limits for the proteins of this size (M.w. 14500).

Animals↗
PubMed1984

Isolation and pharmacological properties of phospholipases A2 from Vipera russelli (Russell's viper) snake venom.

By means of Sephadex G-75 column chromatography, Vipera russelli venom was separated into five fractions. The phospholipase A2 (PLA2) activity was concentrated in Frs. II and III. These two PLA2 fractions were rechromatographed on CM-Sephadex C-50. Several subfractions of Fr. II and Fr. III contained PLA2 activities. Frs. III-3, III-6 and III-10 showed single bands in SDS-polyacrylamide gel electrophoresis with molecular weights estimated to be 15,054, 15,167 and 15,029, and isoelectric points of 4.15, 8.80 and greater than 10, respectively. Fr. III-3 had the most potent neuromuscular blocking action on the chick biventer cervicis nerve-muscle preparation, causing a complete neuromuscular blockade at 3 micrograms/ml. The response of the muscle to ACh, tested after complete blockade, was not altered. Most PLA2 subfractions had hypotensive actions in rats at 0.1 mg/kg. In the guinea-pig lung, Frs. II-5, II-7, III-3, III-6 and III-10 increased the perfusion pressure, which may account for part of their hypotensive actions.

Amino Acids↗
PubMed1984

Effects of phospholipases A2 from Vipera russelli snake venom on blood pressure, plasma prostacyclin level and renin activity in rats.

Vipera russelli venom contains several isoenzymes of phospholipase A2 (PLA2) which were isolated by column chromatography. The effects of PLA2 fractions on blood pressure, plasma prostacyclin level and renin activity were studied in normotensive and renal hypertensive rats. PLA2 fractions II-5, II-7, III-3 and III-6 (0.1 mg/kg) injected i.v. into rats decreased the arterial blood pressure. The hypotensive action of PLA2 fractions was not affected by heat treatment (70-80 degrees C, 30 min, pH 6.8). After indomethacin (30 mg/kg, i.v.), the hypotensive response to PLA2 was markedly reduced. Plasma prostacyclin (PGI2) and thromboxane A2 (TXA2) levels were measured by radioimmunoassays of their degradation products, 6-keto-PGF1 alpha and TXB2, respectively. PLA2 fractions (0.1 mg/kg) induced an increase in plasma PGI2 and TXA2 levels. There was a positive linear correlation between the PLA2-induced hypotensive effect and the ratio of increased 6-keto-PGF1 alpha to TXB2 (r = 0.83) in normotensive rats. In renal hypertensive rats, the increase in PGI2 level was larger than in normotensive rats. Plasma renin activity was also measured by the radioimmunoassay. Plasma renin activity was reduced by PLA2 fractions in renal hypertensive rats, but not in normotensive rats. These results suggest that the hypotensive effect of PLA2 fractions in normotensive rats may be partly due to the increase in plasma prostacyclin and thromboxane A2 levels. In addition to the larger increase in plasma PGI2 level, the reduction in plasma renin activity may also contribute to the greater hypotensive effect of PLA2 fractions in renal hypertensive rats.

6-Ketoprostaglandin F1 alpha↗