Cardioactive effects of hornet venom, Vespa mandarinia

In the experiment of electrocardiogram, the crude venom of giant hornet (Vespa mandarinia) showed cardioactive effects on rat heart. The heart rate was accelerated within 5 min after injection of the venom intraperitoneally, then the heart beat was blocked, resulting in conduction delay. The cardioactive constituent was separated into two components by gel filtration. One which was high molecular species such as protein showed complete atrioventricular block. Another component, having a low molecular weight, was fractionated in 5 peaks, which accelerated heart rate.     

Orientotoxin--a new presynaptic neurotoxin from the venom of the giant hornet Vespa orientalis

Orientotoxin, a novel presynaptically acting neurotoxin from the venom of giant hornet Vespa orientalis, has been isolated by gel filtration and ion exchange chromatography and characterized. The toxin has a molecular mass of 18,000. Highly purified preparations of orientotoxin possessed clearly manifested lysophospholipase activity and can block both induced and spontaneous release of neurotransmitter from the presynaptic nerve membrane.     

Properties of phospholipase A2 from the venom of the large hornet Vespa orientalis

Some properties (catalytic and hemolytic activity, pH and temperature optima, stability, substrate specificity, effects of detergents and metal ions, N-terminal sequence, chemical modification of histidine in the enzyme active center, etc.) of phospholipase A2 from hornet (Vespa orientalis) venom were studied. It was shown that phospholipase A2 from hornet venom differs essentially from other enzymes of this species in terms of stability, catalytic properties and structural features. The active center of the enzyme contains an essential histidine residue, similar to other phospholipases A2 from various sources. Unlike other known forms of phospholipase A2, the enzyme under study exerts a pronounced hemolytic action. The hemolysis is inhibited by Ca2+ at concentrations capable of inducing the activation of the hydrolytic activity of the enzyme.     

Purification and properties of lysophospholipase from the venom of the giant hornet Vespa orientalis

Using biospecific chromatography on polylysocephamide, a toxic phospholipase possessing a presynaptic effect on neuromuscular preparations was isolated from the venom of the giant hornet Vespa orientalis. The enzyme was shown to possess a high hydrolytic activity towards 1-acyllysophosphatidylcholine within a narrow pH range (pH optimum 7.5). The enzyme activity was suppressed by detergents of various chemical composition. Lysophospholipase caused an intensive hemolysis of washed human erythrocytes. The catalytic and hemolytic functions of the enzyme were sensitive to metal ions, however, in a different degree. Ca2+ and Mn2+ activated, while Cu2+ and Zn2+ inhibited the enzyme. Mg2+ and Sr2+ had no effect on the enzyme activity.     

Amino acid sequence of orientotoxins I and II from the venom of the hornet Vespa orientalis

Orientotoxin I, a neurotoxin of presynaptic effect having a lysophospholipase activity, and orientotoxin II, a highly toxic phospholipase A2, were isolated from the hornet Vespa orientalis venom, and their primary structures were determined. Despite their different functional activity, orientotoxin I and II proved to be structural homologues, differing significantly in the amino acid sequence from well-known toxic phospholipase from other sources.     

Low molecular weight peptides from the venom of the giant hornet Vespa orientalis. Structure and function

Three 14-member linear peptides (HR-1, HR-2 and HR-3) capable of degranulating mast cells and thus initiating histamine release were isolated from the venom of the giant hornet Vespa orientalis, using reverse phase high performance liquid chromatography. The complete amino acid sequence of the peptides HR-1 and HR-2 molecules and partial structure of peptide HR-3 were determined, using automatic degradation by the Edman method. It was shown that peptide HR-1 at relatively low concentrations (2-20 micrograms/ml) selectively liberated histamine from rat mast cells and, when taken at higher doses (50-100 micrograms/ml), exerted a non-selective cytotoxic action. Besides, this peptide caused erythrocyte hemolysis, inhibited Ca2+-ATPase with concomitant uncoupling of Ca2+ transport and ATP hydrolysis as well as induced the conductance of lipid bilayer membranes, predominantly for monovalent cations due to the formation of nonspecific single permeability channels.     

Hemolytic effect of phospholipase A2 and orientotoxin from venom of the great hornet, Vespa orientalis

The effect of toxic phospholipase A2 and orientotoxin from the venom of the giant hornet Vespa orientalis on human erythrocytes was studied. It was shown that these venom components are potent hemolytic agents, the efficiency of the latter being by about two orders of magnitude as high as that of phospholipase A2. The hemolytic function of the both components is enhanced in the presence of low concentrations of Ca2+, whereas high concentrations of this cation exert an inhibiting action. Polyvalent cations, in particular, ruthenium red, peptide HR-1, mellitin and cytotoxins Us-1 and Us-5 synergetically increase the hemolytic effect of phospholipase A2. During erythrocyte hemolysis the synergistic effect is manifested upon a combined action of phospholipase A2 and orientotoxin. The combination of these toxins increases the total hemolytic activity and produces a far greater effect than in could be expected in the case of each of these compounds taken separately.     

Mating frequency and genetic relatedness of workers in the hornet Vespa analis (Hymenoptera: Vespidae)

Mating frequency of Vespa analis queens and the genetic relatedness of their workers was analyzed by DNA microsatellite genotyping. Of 20 colonies studied, 18 had a queen inseminated by a single male and two had queens each inseminated by two males. The estimated effective number of matings was 1.05 ± 0.037 (mean ± SE), with 75–85% of the offspring of the two multiply mated queens sired by a single male. The pedigree relatedness between nestmate workers averaged over the 20 colonies was estimated to be 0.74 ± 0.008, almost identical to the predicted value of 0.75 for colonies headed by a singly mated queen. Multiple matrilines; that is, the presence of workers not related to the current queens, were detected in six colonies, suggesting that queen replacement occurred via usurpation of the founding queens in these six colonies. These results demonstrate that the kin structure of V. analis is similar to that reported in other vespid species.     

A lethal neurotoxic protein from Indian king cobra (Ophiophagus hannah) venom

A lethal neurotoxin protein (Toxin CM36) was isolated and purified from the Indian King Cobra (Ophiophagus hannah) venom by CM-Sephadex ion exchange chromatography and HPLC. The purified toxin had a SDS-molecular weight of 15 +/- 0.5 kD. The UV absorption spectra of Toxin CM36 showed a peak at 280 nm and an Emax at 343.8 nm, when excited at 280 nm fluorescence. Toxin CM36 had an LD50 of 3.5 microg/20 g (i.v.) in male albino mice. It exhibited neurotoxicity and produced irreversible blockade of isolated chick biventer cervicis and rat phrenic nerve diaphragm. The neurotoxicity was found to be Ca2+ dependent. Toxin CM36 had no significant effect on isolated guineapig heart and auricle. It also had no effect on blood pressure of cat and rat but produced respiratory apnoea in rat and guineapig. Toxin CM36 lacked phospholipase activity.     

大胡蜂蜂毒中多肽和蛋白质结构和功能的多样性

为证明大胡蜂Vespa magnifica(Smith)蜂毒具有较大的药用开发价值,本研究采用超高效液相色谱-质谱和电泳技术对其多肽和蛋白质的分布进行分析,发现其蛋白质的相对分子质量主要分布在17~45kDa范围内。蜂毒多肽类物质的相对分子质量呈"单峰"式分布,61%在500~3000Da范围内,为大胡蜂蜂毒中多肽含量最为丰富的部分。通过牛津杯法对蜂毒的抑菌活性进行研究,且以HepG2人肝癌细胞及B16黑色素瘤细胞为研究对象,用MTT法检测蜂毒的细胞毒性活性,证明其具有良好的抑菌作用和细胞毒活性,其结果与已报道的其他蜂类既有相似性又存在具体差异,展示了大胡蜂蜂毒的分子多样性,为后续该毒素的物质基础研究及药用价值开发提供参考。     

Purification and properties of a presynaptically acting neurotoxin, mandaratoxin, from hornet (Vespa mandarinia)

A hornet (Vespa mandarinia) neurotoxin, mandaratoxin (MDTX), was purified by simple procedures with column chromatography made on Sephadex G-50 and CM-Sephadex by using an acetate buffer. The molecular weight of homogeneous MDTX was calculated to be approximately 20000 by gel filtration, NaDodSO4 disc gel electrophoresis, and amino acid analysis. MDTX is a single-chain polypeptide. MDTX did not migrate electrophoretically in a basic buffer at pH 8.3 but did so when the buffer was acidic, at pH 4.3. The isoelectric point of the toxin was determined at 9.1 by isoelectric focusing. A relatively high amount of lysine was found in the amino acid analysis. A280nm1% was 15.1. Glucosamine and galactosamine were not detectable by amino acid analysis. MDTX had neither hemolytic nor enzymatic activity. The toxin was heat labile. By use of neuromuscular junctions of a lobster walking leg, it was found that the nanomole range of MDTX irreversibly blocked the excitatory postsynaptic potential without appreciable change in the resting conductance of the postsynaptic membrane. Intracellular recording from the presynaptic nerve fiber showed that MDTX blocked the action potential mainly by reducing the sodium current.     

Structure and mechanics of the tarsal chain in the hornet, Vespa crabro (Hymenoptera: Vespidae): implications on the attachment mechanism

Two combined mechanisms on the hornet tarsus are adapted to attachment to the substrate: a friction-based (claws and spines) and an adhesion-based one (arolium). There are two ranges of substrate roughness optimal for attachment, either very smooth or very rough. There is an intermediate range of substrate grains of small but non-zero size, where both of these mechanisms fail. The optimal size of substrate grains for hornet grasping was 50-100 microm. Maximal hold to the substrate was achieved when surface irregularities were clamped between the claws of opposite legs. In such a position, the insect could withstand an external force which was almost 25 times larger than its own weight. The tarsal chain is an important part of the entire attachment mechanism. The articulations in the kinematic chain of tibia-tarsus-pretarsus are monocondylar. Three tarsal muscles and one head of the claw retractor muscle originate in the tibia. On pull to the retractor tendon, the tarsus bends in a plane. All elements of the tarsal kinematic chain have one active degree of freedom. The distance between the intertarsomeric articulation point and the tendon of the claw retractor (75-194 microm) corresponds to an efficiency of 1 degrees per 1-3 mircom of pulling distance travelled by the tendon. The claw turns about 1 degrees per 4.3-5.0 microm of pulling distance travelled by the unguitractor. The arolium turns forward and downward simultaneously with flexion of the claws. The kinematic chain of the arolium lacks real condylar joints except the joint at the base of the manubrium. Other components are tied by flexible transmissions of the membranous cuticle. The walking hornet rests on distal tarsomeres of extended tarsi. If the retractor tendon inside the tarsus is fixed, passive extension of the tarsomeres might be replaced by claw flexion. Tarsal chain rigidity, measured with the force tester, increased when the retractor tendon was tightened. Probably, pull to the tendon compresses the tarsomeres, increasing friction within contacting areas of rippled surfaces surrounding condyles within articulations.     

Hornet (Vespa orientalis) venom sac extract causes hepatic injury in cats

1. Injection of sublethal doses of hornet venom to cats was followed by increases in serum aminotransferases and alkaline phosphatase, together with hyperglycemia, uremia and hyperkalemia. 2. The blood pH and PO2 fell significantly. 3. All changes occurred within 30 min of injection and were found to be partially reversible. 4. These results may be due to specific liver cell injury. 5. The possibility of a generalized metabolic effect, such as shock, cannot be discounted, although it is quite unlikely.     

Digging activity by the oriental hornet (Vespa orientalis; Hymenoptera,Vespinae) is correlated with solar radiation

Observations were made on the activities of workers of the Oriental hornetVespa orientalis, during flight to and from the nest, on fully active days in months of maximal colony activities. Two types of flight out of the nest were recorded: flight for removal of dug-up soil and flight for foraging of buiding materials and food from the field. The flights of digger workers occur and peak around 1200, (with even slopes down to zero on both sides of the peak). The flight activity curve is gaussian and in accordance with the intensity of solar irradiation. Flight activities of foraging workers are limited in the morning hours but subsequently increase, the curve resembling that of the air temperature at 2m above the soil surface. The flight rhythm of digger hornets in the presence of 2 adjacent outles and the rhythm of activity of digger hornets of 2 abutting nests were also investigated. The results indicate a strong competition among the diggers for flight opportunity during periods of highest insolation intensity. Due to the correlation between the flight of digger hornets and the intensity of sun radiation, it is assumed that hornets do make use of solar energy for flight purposes.     

Viability of thermal imaging in detecting nests of the invasive hornet Vespa velutina

Vespa velutina is an invasive hornet species that is colonising Europe,generating considerable impacts on honeybees,beekeeping and biodiversity.Control and early warning strategies for this species are mainly based on monitoring plans and procedures of nest detection and destruction.Technological tools(harmonic radar,radio-telemetry)have been developed to increase the probabilities of nest detection in new outbreaks.Since hornets are able to regulate nest temperature,thermography may represent an additional technique that may be used,both alone or in support to other techniques.In this study,the viability of thermal imaging in detecting nests of V.velutina was evaluated in controlled conditions.The influence of different environmental and operative variables(time of the day,presence/absence of leaves covering the nest,distance between the nest and the operator)were tested on three nests detected during August 2018 in Italy.All the nests were detectable by thermal imaging,but environmental and operative variables affect their detectability.The temperature difference between the nests and the surrounding reaches its maximum before sunrise and without a tree canopy covering the nests.Although nests were visible in some cases from 30 m,the detectability was higher at shorter distances,even if this variable may also depend on infrared camera resolution.An increase in the environmental temperature also generates a decrease of nest detectability.Although some limitations could occur,these results show the applicability of thermography in detecting V velutina nests before the beginning of the reproductive phase,and consequently its potentiality in control strategies.     

Building activity and longevity of queenless groups of the Oriental hornet,Vespa orientalis

The effect of group size on behavioral parameters of the Oriental hornet,Vespa orientalis, was assessed experimentally under laboratory conditions. Hornet groups of various sizes (ranging from 1 to 100 individuals per group) comprised of young individuals (0–24 hr of age) devoid of a queen were placed in artificial breeding boxes (ABBs). The following three quantitative parameters were evaluated: the amount and rate of building as a function of the number of hornets in the group, the rate of oviposition as, related to group size and the longevity of hornets as a function of their group size. The probability for the occurrence of these events was similarly considered and additional behavioral parameters were only assessed qualitatively. Results of this investigation revealed a relation between the three mentioned quantitative behavioral parameters and the number of hornets per group. The number of hornets per group was positively related to the extent of building, the number of cells built by a group is , but negatively related to the rate of building. As for the delay of building, a non-monotone relation was found. The relation between number of hornets per group and the oviposition delay was found to be non-monotone; the number of hornets per group and their longevity were found to be inversely related. Discrepanices were recorded on the very small (1–2 individuals) or very large (100 individuals) hornet groups.