The venom apparatus of the globiferous pedicellariae of the toxopneustid Sphaerechinus granularis (Echinodermata,Echinoida): Fine structure and mechanism of venom discharge

Summary Globiferous pedicellariae of Sphaerechinus granularis are venomous defensive appendages consisting of a stalk bearing a head made of three movable jaws. Each jaw is supported by a calcareous valve ending with a terminal grooved tooth. A venom apparatus is located in each jaw and consists of a venom gland surrounded by a muscular envelope and terminating in a duct which completely encircles the terminal tooth of the valve. Contrary to previous statements, the duct does not lie inside the groove of the terminal tooth. In mature pedicellariae, the venom is stored in intracellular vacuoles of highly differentiated cells which are no longer active. The cells fill the whole space of the venom gland which is without a lumen; they are segregated into two types that occur in distinct regions and differ from each other by morphological and staining properties of their secretions. Upon contraction of the muscular envelope, the venom is released via a holocrine mechanism and infiltrates the predator's tissues through the wound inflicted by the three calcareous teeth of the valves. In no case is the venom emitted through the tooth groove.     

Ultrastructure of the venom gland of the scorpion,Centruroides sculpturatus (Ewing)

The venom apparatus of the scorpion, C. sculpturatus (Ewing) was studied with light and electron microscopy. Each of the paired glands is lined by secretory epithelium made up of a single layer of columnar cells. Extensive folding in the epithelial layer creates a primitive acinar gland. The secretory products are either membrane-bound or unbound vesicles with discrete morphologies and are observed in the extruded venom, within the lumen of the gland, and within single secretory cells. The venom apparatus, including connective tissues, nerve cells, and muscle tunic is described and correlations are made with observations in other Athropods.     

Comparative morphology of the venom apparatus in the braconid wasp subfamily Rogadinae (Insecta, Hymenoptera, Braconidae) and related taxa

Zaldivar‐River ó n, A., Areekul, B., Shaw, M. R. & Quicke, D. L. J. (2004). Comparative morphology of the venom apparatus in the braconid wasp subfamily Rogadinae (Insecta, Hymenoptera, Braconidae) and related taxa. —Zoologica Scripta, 33, 223–237. The morphology of the venom apparatus intima in representatives of 38 genera of the problematic braconid wasp subfamily Rogadinae and other cyclostome braconids was investigated and a preliminary phylogenetic analysis for the group was performed with the information obtained. Despite the limited number of characters, the data suggest several relationships at various taxonomic levels. The venom apparatus in the Clinocentrini and the Stiropiini is relatively unmodified and similar to that found in other genera previously placed within a broader concept of the Rogadinae (e.g. genera of Lysitermini, Pentatermini, Tetratermini, Hormiini) and also to that of the Betylobraconinae. The presence of a cone of filaments located inside the secondary venom duct near to its insertion on the venom reservoir/primary venom duct is proposed as a synapomorphy for the tribe Rogadini to the exclusion of Stiropiini, Clinocentrini and Yeliconini. Other features of the secondary venom duct and its insertion on the venom reservoir/primary venom duct support a number of relationships between the genera of the Rogadini and also within the large genus Aleiodes. A clade containing 15 Rogadini genera (Bathoteca, Bathotecoides, Bulborogas, Canalirogas, Colastomion, Conspinaria, Cystomastacoides, Macrostomion, Megarhogas, Myocron, Pholichora, Rectivena, Rogas, Spinaria and Triraphis) is supported by the presence of a thickened and short secondary venom duct, whereas the different members of Aleiodes (excluding members of the subgenus Heterogamus) and Cordylorhogas are distinguished by having a recessed secondary venom duct with well‐defined and numerous internal filaments. New World Rogas species exhibit a unique venom apparatus and may not be closely related to the Old World ones. Features of the venom apparatus of the enigmatic genus Telengaia and the exothecine genera Shawiana and Colastes suggest that the Telengainae and Exothecinae are both closely related to the Braconinae, Gnamptodontinae, and possibly to the Opiinae and Alysiinae. An unsculptured venom reservoir was found in one specimen of the type species of Avga, A. choaspes, which is consistent with it occupying either a very basal position within the cyclostome braconids or belonging to a recently recognized ‘Gondwanan’ clade that also includes the Aphidiinae.     

Histology,histochemistry, and emptying mechanism of the venom glands of some elapid snakes

The venom glands of several species of elapid snakes are described. The main venom gland consists of many tubules which usually contain large amounts of secretion product. The accessory gland surrounds the entire venom duct and is usually composed of uniform mucous epithelium. The epithelium lining the tubules of the accessory gland of Naja naja is composed of two distinct types of cells. Histochemical tests indicate that the main venom gland reacts with mercury bromphenol blue and PAS but not with alcian blue. The accessory gland reacts with PAS and alcian blue, and not with mercury bromphenol blue. Treatment of sections with sialidase demonstrates the presence of a sialomucin in the accessory gland. Stimulation of the muscles associated with the venom gland offers an indication of the venom expulsion mechanism of Bungarus caeruleus. A comparison of the venom apparatus of elapid and viperid snakes emphasizes marked differences in the internal anatomy of the venom glands, muscles associated with the gland, and arrangement of glandular components. The morphological differences and dissimilar venom expulsion mechanisms support the recent view of the polyphyletic origin of venomous snakes.     

Expression pattern analysis of odorant‐binding proteins in the pea aphid Acyrthosiphon pisum

Odorant‐binding proteins (OBPs) are soluble proteins mediating chemoreception in insects. In previous research, we investigated the molecular mechanisms adopted by aphids to detect the alarm pheromone (E)‐β‐farnesene and we found that the recognition of this and structurally related molecules is mediated by OBP3 and OBP7. Here, we show the differential expression patterns of 5 selected OBPs (OBP1, OBP3, OBP6, OBP7, OBP8) obtained performing quantitative RT‐PCR and immunolocalization experiments in different body parts of adults and in the 5 developmental instars, including winged and unwinged morphs, of the pea aphid Acyrthosiphon pisum. The results provide an overall picture that allows us to speculate on the relationship between the differential expression of OBPs and their putative function. The expression of OBP3, OBP6, and OBP7 in the antennal sensilla suggests a chemosensory function for these proteins, whereas the constant expression level of OBP8 in all instars could suggest a conserved role. Moreover, OBP1 and OBP3 are also expressed in nonsensory organs. A light and scanning electron microscopy study of sensilla on different body parts of aphid, in particular antennae, legs, mouthparts, and cornicles‐cauda, completes this research providing a guide to facilitate the mapping of OBP expression profiles.     

Venom gland and reservoir morphology in cynipoid wasps

The venom apparatus morphology was examined in 25 species of Cynipoidea, representing 11 parasitoid taxa; 12 gall inducers and two inquilines. Typically the venom apparatus consists of an oval or bilobed reservoir connected to the ovipositor apparatus by a very short venom duct at the anterior end and to a single elongate unbranched venom gland at or near its posterior end. The Dufour's gland was not found in any of the examined species. The elongate unbranched venom gland and the absence of the Dufour's gland are putative cynipoid synapomorphies. The shape and size of especially the venom reservoir were found to vary considerably within the Cynipoidea. It is typically less prominent in the parasitoid taxa than in the gall inducers. Exceptions include the poppy gallers Barbotinia and Aylax, in which the venom reservoirs were remarkably small and in the rose galler Diplolepis, where only a rudimentary venom apparatus was found. Possible functional and phylogenetic implications of cynipoid venom apparatus features are discussed.     

Targeting Holliday junctions by origin DNA-binding protein of herpes simplex virus type 1

In the present paper, the interactions of the origin binding protein (OBP) of herpes simplex virus type 1 (HSV1) with synthetic four-way Holliday junctions (HJs) were studied using electrophoresis mobility shift assay and the FRET method and compared with the interactions of the protein with duplex and single-stranded DNAs. It has been found that OBP exhibits a strong preference for binding to four-way and three-way DNA junctions and possesses much lower affinities to duplex and single-stranded DNAs. The protein forms three types of complexes with HJs. It forms complexes I and II which are reminiscent of the tetramer and octamer complexes with four-way junction of HJ-specific protein RuvA of Escherichia coli. The binding approaches saturation level when two OBP dimers are bound per junction. In the presence of Mg²⁺ ions (≥2 mM) OBP also interacts with HJ in the stacked arm form (complex III). In the presence of 5 mM ATP and 10 mM Mg²⁺ ions OBP catalyzes processing of the HJ in which one of the annealed oligonucleotides has a 3′-terminal tail containing 20 unpaired thymine residues. The observed preference of OBP for binding to the four-way DNA junctions provides a basis for suggestion that OBP induces large DNA structural changes upon binding to Box I and Box II sites in OriS. These changes involve the bending and partial melting of the DNA at A+T-rich spacer and also include the formation of HJ containing Box I and Box II inverted repeats and flanking DNA sequences.     

REGULATION OF PROTEIN SYNTHESIS IN THE VENOM GLAND OF VIPERID SNAKES

Morphological changes in the venom gland of V. ammodytes were studied after the removal of the venom from the gland lumina (milking) It was found that the height of the secretory cells was changed during the secretory cycle. The patterns of the rough endoplasmic reticulum and of the Golgi complex were changed as well Milking induced an increased incorporation of [¹⁴C]amino acids into total and venom proteins In V ammodytes, during the first day after milking, 25% of the total counts in protein were precipitable by anti-venom serum, while at 8 days, 80% of the proteins synthesized were venom proteins At this stage, the incorporation was 10- and 20-fold that of unmilked glands for total and venom proteins, respectively. Venom was accumulated (secreted) in the gland lumina of V. ammodytes at a relatively high rate up to 2 wk after milking and leveled off afterwards. Intact glands and gland slices of V ammodytes and V palaestinae, taken from snakes a few days after milking, incorporated [¹⁴C]amino acids into proteins in vitro at a rate higher than that of unmilked glands. The activity of two exportable enzymes (phosphodiesterase and benzoyl arginyl ethyl esterase) was assayed in gland homogenates of V. ammodytes. It was found that 2–3 wk after milking, the intracellular level of these enzymes was up to 2-fold that of unmilked glands.     

Venom induces alarm behaviour in the social wasp Polybioides raphigastra (Hymenoptera: Vespidae): an investigation of alarm behaviour, venom volatiles and sting autotomy

Chemicals from the venom gland elicited alarm behaviour and attack in the Asian polistine wasp Polybioides raphigastra. When presented with crushed venom glands workers of this wasp respond with a mass stinging attack. Gas chromatography–mass spectrometry analyses show that the major volatiles in the venom gland are alkanes, monounsaturated alkenes and 2-alcohols. Several pyrazines, a spiroacetal and aromatics were also identified as trace compounds. The anatomy and morphology of the sting apparatus are reported, and we describe sting autotomy in this wasp. This is the first such report for the Ropalidiinae. The structures responsible for autotomy are likely to be large barbs present on the sting lancets, and a conspicuous tooth present on the medial side of the left lancet. Sting autotomy in P. raphigastra probably plays an important role in the localization of sites of attack by wasps defending the nest.     

Comparative studies on the structure and development of the venom‐delivery system of centipedes,and a hypothesis on the origin of this evolutionary novelty

The venom‐injecting forcipules of centipedes represent an evolutionary novelty that appeared in the centipede stem lineage more than 400 Ma. No other lineage of arthropods (or indeed of animals) has evolved claws for injecting venom from a pair of walking legs. However, little is known of the development, ultrastructure, or detailed function of centipede forcipules. Here, we provide comparative structural information on the venom duct apparatus that is the main functional system within each forcipule, based on scanning electron microscopy and transmission electron microscopy studies. We also give comparative developmental information, using DAPI staining, on embryonic forcipules from the four main centipede orders, including Scutigeromorpha. The photographs of Scutigera embryos we present are the first to be published for any species belonging to this order. The structure of the venom apparatus within each forcipule represents a discrete element of the novelty, whose origin requires a special explanation. This is in contrast to the novel external shape of the forcipules, which can be arrived at gradually by a series of changes from the starting point of a standard walking leg. Drawing on a proposed structural homology between venom glands and epidermal glands, we present a hypothesis of how the venom gland and duct may have arisen in evolution.     

Melanin deposits associated with the venom glands of snakes

Melanin deposits in the heads of both true vipers (Viperinae) and pit vipers (Crotalinae) are concentrated over the dorsal and dorsolateral aspects of the venom glands. This pigment may occur in any or all of six sites which include the epidermis, dermis, tissues covering the venom glands, and the interior of the glands themselves. The extreme localization of these melanin deposits suggests that they shield the venom glands from light. Calculations indicate that without such shielding the light energy penetrating the venom glands in the visible and ultraviolet portions of the solar spectrum would damage the venom-synthesizing apparatus and detoxify stored venom. Elapid and hydrophiid snakes have less dense pigment over the venom gland than vipers. Literature reports indicate that elapid venom is less sensitive to photodetoxification than is venom from vipers. Most colubrid snakes, including several with protein-secreting Duvernoy's glands, have little or no melanin associated with the glands. Venomous colubrids in the genera Ahaetulla, Dryophis, Leptophis, and Oxybelis have pigment over the glands as dense as that seen in vipers. Iridophores probably also shield venom glands from radiation. In puff adders and Gaboon vipers (Bitis) there appears to be an ontogenetic change in the shielding of the venom glands from melanocytes in young individuals to iridophores in adults.     

Evolution of venom delivery structures in madtom catfishes (Siluriformes: Ictaluridae)

The use of venom to subdue prey or deter predators has evolved multiple times in numerous animal lineages. Catfishes represent one of the most easily recognized, but least studied groups of venomous fishes. Venom glands surround spines on the dorsal and pectoral fins that serve as venom delivery structures. Species of madtom catfishes in the genus Noturus were found to each have one of four venom delivery morphologies: (1) smooth spine with no venom gland; (2) smooth spine with venom gland associated with shaft of spine; (3) serrated spine with venom gland associated with shaft of spine; and (4) serrated spine with venom gland associated with shaft of spine and posterior serrations. Analyses accounting for the phylogenetic history of Noturus species suggest that a serrated pectoral spine with a venom gland is the ancestral condition for the genus. The presence of serrations and a venom gland have been largely conserved among Noturus species, but sting morphology has changed at least five times within the genus. Four of these changes have resulted in a loss of morphological complexity, including the loss of posterior serrations, loss of venom glands associated with the posterior serrations, and one complete loss of the venom gland. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 115–129.     

Morphology and ultrastructure of the convoluted gland in the ant Dinoponera australis (Hymenoptera: Formicidae)

The morphology and fine structure of the convoluted gland inside the venom reservoir of the ponerine ant Dinoponera australis (Hymenoptera: Formicidae) are described. The cells of the convoluted gland can be divided into 3 major groups: (1) epithelial cells, (2) glandular cells with end apparatus secreting into the tubule inside the convoluted gland, and (3) glandular cells with end apparatus secreting directly into the venom reservoir. A fourth group of cells belonging to the venom gland of this ant is also discussed as (4) secretory cells of the free tubule (not a part of the convoluted gland). The epithelial cells in the convoluted gland do not have many organelles. Most cells of group 3 are characterized by numerous mitochondria. In some of these cells, the mitochondria possess tubular cristae. Tubule cells of group 2 inside the convoluted gland, possess little rough endoplasmic reticulum when compared with cells of group 4, situated in the free tubule.     

Venom gland of the ichneumonid Diadromus collaris： morphology, ultrastructure and age-related changes

Females of the solitary parasitoid Diadromus collaris （Insecta： Hymenoptera： Ichneumonidae） lay eggs in the pupae of Plutella xylostella （Lepidoptera： Plutellidae）, and the venom is synchronously injected into hosts. The venom apparatus consists of two glandular tubules terminating in a common reservoir, A ductule connects the reservoir with the sting apparatus, by which the reservoir content enters the latter. Secretory units line the two glandular tubules. All secretory cells belong to dermal gland type Ⅲ. Dermal gland cells in glandular tubules are more abundant and developed than those in the reservoir. There are extensive rough endoplasmic reticulum and electrondense vesicles, and the microvilli are well developed. By the cuticle-lined central funnel secretion products of secretory units reach the reservoir. Moreover, the secretory apparatus undergoes age-related changes. The secretory units in the venom gland are better developed and more vigorous 7 days after eclosion than those 1 day after eclosion; autolytic processes occur 15 days after eclosion, and the tissue of the reservoir is more prostrate 15 day after eclosion than those 1 day after eclosion. The ovipostion peak of this parasitoid, about 3-7 days after eclosion, corresponds with the period when the venom gland is highly developed in the life span of the wasp.