P. Mantel

Poneratoxin, a novel peptide neurotoxin from the venom of the ant, Paraponera clavata.

1. At concentrations varying from 10(-8) to 10(-6) M synthetic poneratoxin (PoTX) is a strong, but very slowly acting agonist for smooth muscles and its blocks synaptic transmission in the insect CNS in a concentration-dependent manner and depolarizes giant interneurons. 2. However, in isolated dorsal unpaired median cells 10(-6) M PoTX causes only a reversible hyperpolarization of about 5 mV. 3. At concentrations from 10(-8) to 10(-6) M PoTX affects the electrical activity of isolated cockroach axons, as well as isolated frog and rat skeletal muscle fibres. 4. PoTX prolongs action potentials and induces slow automatic activity, due to a slow Na(+)-current activation at very negative values of potential and due to slow deactivation.

Two kinins isolated from an extract of the venom reservoirs of the solitary wasp Megascolia flavifrons.

From an extract of the venom reservoirs of the wasp Megascolia flavifrons two kinins have been isolated. The sequences of amino acids are: Arg-Pro-Pro-Gly-Phe-Thr-Pro-Phe-Arg (Thr6-bradykinin) and Arg-Pro-Pro-Gly-Phe-Thr-Pro-Phe-Arg-Lys-Ala (Thr6-bradykinin-Lys-Ala). The bradykinin-like effects of the venom on a number of vertebrate smooth muscle preparations can be explained by the actions of these kinins.

The pharmacology of Microbracon venom

1. Wasps of the genus Microbracon generally paralyse larvae of Lepidoptera. The wasp larva is exophagous on the paralysed host. The venom acts slowly and causes a flaccid paralysis. The venom of M. hebetor is extremely active in Lepidoptera, less active in honeybee workers, much less active in locusts and mealworms and probably inactive in non-insects. 2. In Lepidoptera and in locusts the venom presynaptically blocks the excitatory, but not the inhibitory, neuromuscular transmission. M. hebetor venom contains two high mol. wt toxins. A-MTX and B-MTX, with essentially the same action on neuromuscular transmission as the crude venom. Differences in dose-response curves of the two toxins, as well as differences in sensitivity to the two toxins between insect species are described. In wax moth larvae both A-MTX and B-MTX cause a slow and transient paralysis with a maximal effect after about 20 hr. The rate of recovery is dose-dependently decreased by the toxins.

Threonine6-bradykinin in the venom of the wasp Colpa interrupta (F.) presynaptically blocks nicotinic synaptic transmission in the insect CNS

1. The venom of the solitary scoliid wasp Colpa interrupta (F.) shows a kinin-activity, when tested on a cascade of mammalian smooth muscle preparations, and, in addition, a contraction of the rat colon. 2. The venom also irreversibly blocks the nicotinic synaptic transmission from the cercal nerve to a giant interneuron in the sixth abdominal ganglion of the cockroach, Periplaneta americana. 3. The same activities have been found within one HPLC fraction. 4. However, rechromatography of this fraction resulted in four subfractions being active on smooth muscles. 5. One fraction caused contraction of the colon, three other fractions contained kinin-activity. 6. Only the most active kinin fraction blocked synaptic transmission in the insect CNS. 7. This fraction contained threonine-bradykinin. 8. Synthetic Thr-bradykinin causes irreversible presynaptic activation-induced block of transmission in the insect CNS.

The venom of Ampulex Compressa—effects on behaviour and synaptic transmission of cockroaches

1. The solitary wasp Ampulex compressa stings a cockroach, Periplaneta americana, twice. 2. The first sting into the ventral thorax results in a transient paralysis. During this paralysis the wasp stings the suboesophageal ganglion, which gradually results in a permanent deactivation. 3. The venom gland is a paired and highly branched organ, with a common ductus venatus. The large lumen is lined with a folded cuticula. No venom reservoir is present. 4. Extract of the venom gland induces a slow contraction of the guinea pig ileum. 5. The agonist present in the venom cannot be identified with a known agonist. 6. Venom gland extract blocks synaptic transmission from the cercal nerve to giant neurons in the sixth abdominal ganglion of the cockroach. 7. The block develops gradually, like the gradual appearance of the effects of the sting into the suboesophageal ganglion on the behaviour of the cockroach.

Megascoliakinin, a bradykinin-like compound in the venom of Megascolia flavifrons fab. (Hymenoptera: Scoliidae)

The pharmacological and immunological properties of the venom of Megascolia flavifrons are compared with those of bradykinin and a number of bradykinin analogues. It is postulated that this venom contains a peptide, megascoliakinin, with a bradykinin-like sequence of amino acids, elongated at the C-terminal end with an unknown structure.

Pharmacological characterization and chemical fractionation of the venom of the ponerine ant, Paraponera clavata (F.)

1. The neurotoxic action of the venom of the ponerine ant, Paraponera clavata, was studied using a cascade of mammalian smooth muscle preparations and a preparation for investigating transmission from fibres of the cercal nerve to a giant interneuron in the sixth abdominal ganglion of the cockroach. 2. The venom contains three toxic fractions that block synaptic transmission in the insect central nervous system. 3. Two of these fractions have agonistic action on mammalian smooth muscle preparations. 4. One of the later fractions was characterized pharmacologically as containing a kinin. 5. The other, and most active neurotoxic fraction, was rechromatographed, resulting in the purification of a peptide of 25 amino acids residues, called poneratoxin, PoTX: Phe-Leu-Pro-Leu-Leu-Ile-Leu-Gly-Ser-Leu-Leu-Met-Thr-Pro-Pro-Val-Ile-Gln- Ala-Ile-His-Asp-Ala-Gln-Arg-HN2.

Smooth muscle contracting compounds in the venom of Megascolia flavifrons (Hym: Scoliidae) with notes on the stinging behaviour

1. The wasp Megascolia flavifrons stings larvae of the stag beetle Oryctes nasicornis on the ventral side of all segments, except the last three, which do not contain nerve ganglia. 2. Experiments indicate a central rather than a peripheral action of the venom. 3. From pharmacological analysis it is concluded that the venom does not contain cholinergic or serotonergic activity, but contains histamine- and bradykinin-like substances. 4. The presence of histamine was confirmed by a radioenzymatic method.

Effect of venom of the digger wasp Philanthus triangulum F. on the sixth abdominal ganglion of the cockroach

Abstract 1. The central action of venom preparations from the digger wasp Philanthus triangulum on the cercal nerve-giant fibre preparation of the sixth abdominal ganglion of the cockroach Periplaneta americana , has been studied using the mannitol-gap technique. 2. At concentrations which are probably lower than the concentrations obtained after a sting of the wasp into the ganglion mass of the honeybee worker, certain venom preparations caused depolarization of the giant neurons, block of synaptic transmission and a concurrent depolarization of fibres in nerve XI. 3. The venom preparation possesses practically no anticholinesterase activity. 4. The centrally active components have not yet been purified, but have been separated from the components affecting neuromuscular transmission. 5. The active components probably have a molecular weight of less than 700.

Effect of proctolin, BPP5a and related peptides on rhythmic contractions in Locusta migratoria

Abstract 1. Small myogenic rhythmic contractions of the extensor tibiae of L. migratoria can be induced by proctolin (10 −10 −10 −9 mol/1), by BPP 5a (10 −9 −10 −8 mol/1), by −9 mol/1, and by NO 2 -proctolin (10 −6 mol/1). 2. Other penta- and hexapeptides tested were inactive. 3. It is suggested that the tetrapeptide sequence, consisting of a basic, an aromatic, an aliphatic amino acid and proline is essential for the specific activity.