Spider Oxyopes Research Articles

Linear Peptides-A Combinatorial Innovation in the Venom of Some Modern Spiders.

In the venom of spiders, linear peptides (LPs), also called cytolytical or antimicrobial peptides, represent a largely neglected group of mostly membrane active substances that contribute in some spider species considerably to the killing power of spider venom. By next-generation sequencing venom gland transcriptome analysis, we investigated 48 spider species from 23 spider families and detected LPs in 20 species, belonging to five spider families (Ctenidae, Lycosidae, Oxyopidae, Pisauridae, and Zodariidae). The structural diversity is extraordinary high in some species: the lynx spider Oxyopes heterophthalmus contains 62 and the lycosid Pardosa palustris 60 different LPs. In total, we identified 524 linear peptide structures and some of them are in lycosids identical on amino acid level. LPs are mainly encoded in complex precursor structures in which, after the signal peptide and propeptide, 13 or more LPs (Hogna radiata) are connected by linkers. Besides Cupiennius species, also in Oxyopidae, posttranslational modifications of some precursor structures result in the formation of two-chain peptides. It is obvious that complex precursor structures represent a very suitable and fast method to produce a high number and a high diversity of bioactive LPs as economically as possible. At least in Lycosidae, Oxyopidae, and in the genus Cupiennius, LPs reach very high Transcripts Per Kilobase Million values, indicating functional importance within the envenomation process.

The complete mitochondrial genome of Oxyopes hupingensis (Araneae: Oxyopidae): characterization and phylogenetic analysis

The complete mitochondrial genome of the lynx spider Oxyopes hupingensis was characterized in this study. The circular genome is 15,078 bp in length (GenBank accession number MK518391), containing 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, 2 ribosomal RNA genes, and a control region. Its gene direction and arrangement are identical to those of other spider mitogenomes. The overall base composition is 34.76% A, 43.11% T, 8.04% C, and 14.09% G, showing AT-rich feature (77.87%). Ten PCGs are initiated with typical ATN start codons, three genes (cox2, cox3, and nad4) begin with TTG. Nine PCGs stop with complete termination codon TAA and TAG, cox1, nad4, nad4L, and cob are terminated with T. Twenty-three reading frame overlaps and four intergenic regions were found in the mitogenome of O. hupingensis. Three tRNAs lack the dihydrouracil (DHU) arm, whereas eight tRNAs lose the TΨC arm stems. Phylogenetic tree based on concatenated amino acid sequences of 13 PCGs shows that O. hupingensis has a close phylogenetic relationship with Oxyopes sertatus and belongs to Oxyopidae.

Lethal and sublethal effects of Embelia ribes and two commercial pesticides on a generalist predator

AbstractEven as new substances show promise as biopesticides for controlling pests due to their natural properties and high effectiveness in inhibiting pests, their side effects on non‐target organisms must nevertheless be evaluated before they can be included into integrated pest management systems. In this study, a crude extract from dried leaves of Embelia ribes was evaluated together with two commercial pesticides: azadirachtin (a natural product) and amitraz (a synthetic acaricide). We examined both lethal and sublethal effects on the predatory potential of the lynx spider Oxyopes lineatipes, which is among the most dominant predator in tropical agricultural agroecosystems. We found that the spider's mortality increased with rising concentration of both commercial products, azadirachtin and amitraz, but not with rising concentration of the extracts from E. ribes. The greatest mortality occurred when amitraz was used. That material caused almost 100% spider mortality in the doses recommended for field spraying. Azadirachtin significantly reduced the rate at which O. lineatipes captured prey, while there was no significant difference in capture rates among spiders exposed to a control treatment and the E. ribes treatment. Considering its absence of unfavourable impacts on O. lineatipes in terms of mortality and predatory activity, the plant extract from E. ribes shows promise as a new biopesticide material. In contrast, azadirachtin, which has been considered as safe for non‐target organisms, exhibited slight lethal effect only in higher concentrations and strong sublethal effect by reducing spiders’ predation rate.

Behavioral predictability in a lynx spider is interactively influenced by mean behavior, prey density, and an insecticide.

Behavioral predictability, i.e., short-term intra-individual variability under relatively constant environmental conditions, has only recently begun to gain attention. It is unknown, however, whether predictability of individuals with distinct mean behavior changes differently as a response to ecological factors such as resource availability. Moreover, the response might be affected by anthropogenic contaminants that are ubiquitous in the environment and that can affect animals’ variability in behavior. Here, we investigated the relationship between mean predatory activity and predictability in predatory activity along a prey density gradient in the lynx spider Oxyopes lineatipes. We further examined how this relationship is influenced by insecticides, azadirachtin, and a plant extract from Embelia ribes. We found that all studied variables affected the predictability. In the control and Embelia treatments, that did not differ significantly, the predictability decreased with increasing prey density in a mean behavior-specific way. Individuals with low mean predatory activity were relatively less predictable than were those with high activity from low to moderate prey densities but more predictable at high prey densities. Azadirachtin altered this pattern and the individuals with low predatory activity were less predictable than were those with high predatory activity along the whole gradient of prey density. Our results show that predictability can change along an environmental gradient depending on a mean behavior. The relative predictability of the individuals with distinct mean behavior can depend on the value of the environmental gradient. In addition, this relationship can be affected by anthropogenic contaminants such as pesticides.

Heterologous expression of five disulfide-bonded insecticidal spider peptides

The genes of the five disulfide-bonded peptide toxins 1 and 2 (named Oxytoxins or Oxotoxins) from the spider Oxyopes lineatus were cloned into the expression vector pQE30 containing a 6His-tag and a Factor Xa proteolytic cleavage region. These two recombinant vectors were transfected into Escherichia coli BL21 cells and expressed under induction with isopropyl thiogalactoside (IPTG). The product of each gene was named HisrOxyTx1 or HisrOxyTx2, and the protein expression was ca 14 and 6 mg/L of culture medium, respectively. Either recombinant toxin HisrOxyTx1 or HisrOxyTx2 were found exclusively in inclusion bodies, which were solubilized using a chaotropic agent, and then, purified using affinity chromatography and reverse-phase HPLC (RP-HPLC). The HisrOxyTx1 and HisrOxyTx2 products, obtained from the affinity chromatographic step, showed several peptide fractions having the same molecular mass of 9913.1 and 8030.1 Da, respectively, indicating that both HisrOxyTx1 and HisrOxyTx2 were oxidized forming several distinct disulfide bridge arrangements. The isoforms of both HisrOxyTx1 and HisrOxyTx2 after DTT reduction eluted from the column as a single protein component of 9923 and 8040 Da, respectively. In vitro folding of either HisrOxyTx1 or HisrOxyTx2 yielded single oxidized components, which were cleaved independently by the proteolytic enzyme Factor Xa to give the recombinant peptides rOxyTx1 and rOxyTx2. The experimental molecular masses of rOxyTx1 and rOxyTx2 were 8059.0 and 6176.4 Da, respectively, which agree with their expected theoretical masses. The recombinant peptides rOxyTx1 and rOxyTx2 showed lower but comparable toxicity to the native toxins when injected into lepidopteran larvae; furthermore, rOxyTx1 was able to inhibit calcium ion currents on dorsal unpaired median (DUM) neurons from Periplaneta americana.

Biocontrol potential of the lynx spider Oxyopes javanus (Araneae: Oxyopidae) against the tea mosquito bug, Helopeltis theivora (Heteroptera: Miridae)

The tea (Camellia sinensis (L.) Kuntze) industry is the backbone of the agroeconomy of the North Bengal region located at the foothills of the Himalayas in North-East (NE) India. This region accounts for about 25% of the total tea production in India. The tea mosquito bug, Helopeltis theivora Waterhouse, is one of the most devastating sucking pests of tea in this region. Various kinds of synthetic insecticides are continuously sprayed to control this bug. The lynx spider Oxyopes javanus. Thorell has been found to remain associated with tea plants and feed on H. theivora. The present study investigated the predation potential and efficacy of the O. javanus spider against one of its most common prey species, H. theivora. In the laboratory, with an increase in H. theivora density, the predation rate of both male and female O. javanus increased. Per capita predation rates exhibited by male and female O. javanus per day against adult H. theivora were 3.67 ± 1.52 and 11.67 ± 1.53 (mean ± standard deviation), respectively. At a reasonably small prey density, the prey consumption rate was highest, reaching up to 100%, indicating that the spider predator has the potential to eliminate smaller populations of the pest. The predation effectiveness calculated using Holling’s disc equation was 6.08 and 356.58 for male and female O. javanus, respectively. The prey handling time was 0.138 day for male O. javanus and 0.012 day for female O. javanus. Female O. javanus exhibited about fivefold higher searching efficacy than male O. javanus. It appears that the conservation or augmentation of O. javanus in the tea ecosystem can provide effective biological management of the major tea pest, H. theivora, in sub-Himalayan foothills and plains of NE India.

捕食者对空心莲子草叶甲种群的生物胁迫

Generalist predators are often applied in biological control of pests. Sine generalist predators often prey on herbivorous insects unselectively,they also influence biological control of weeds with herbivorous insects. The alligator weedflea beetle,Agasicles hygrophila( Coleoptera: Chrysomelidae) is acted as a specific biological control of the alligator weed Alternanthera philoxeroides( Amaranthacese: Alternanthera),and it had been introduced to China from Florida,USA. It has performed a good control effect on A. philoxeroides since the beetle was released in the areas invaded by A. philoxeroides. Although the population of A. hygrophila had been established and spread to adjacent regions from the release sites,the population abundance of the beetle maintains only a lower level. Thus,it can not suppress effectively the population expansion and spread of A. philoxeroides. We found that many generalist predator species such as spiders and predatory insects live in the habitat of A. philoxeroides. Whether the generalist predators are a biotic stress factor for suppressing the population expansion of the beetle? To demonstrate this problem,a predator-prey system including predators,i. e. lady beetle Propylaea japonica( Coleoptera: Coccinellidae),spider Oxyopes sertatus( Araneae: Oxyopidae) and Pirata subpiraticus( Araneae: Lycosidae),and host preys,i. e. egg,1st—3rdinstar larva and adult of A. hygrophila was built. Then the daily eating number of the above three predators on different immature stages and adults of A. hygrophila was observed in the laboratory. This aim to understand the biotic stress of predators on A. hygrophila in a natural ecosystem that may evaluate objectively the biological control efficiency of A. hygrophila on A. philoxeroides in the field. The results showed that P. japonica,O. sertatus and P. subpiraticus could feed on eggs as well as 1st—2ndinstar larvae of A. hygrophila. Both O. sertatus and P. subpiraticus could feed on 3rdinstar larvae of A. hygrophila. The predatory capacities of P. japonica, O. sertatus and P. subpiraticus to eggs and larvae of A. hygrophila increased,but searching efficiency of the predators decreased with the increasing densities of prey. However,the three predators did not prey on adult A. hygrophila in this experiment. The predatory function responses of P. japonica and P. subpiraticus on eggs,1st—2ndinstar larvae,and of O. sertatus on eggs,1st—3rdinstar larvae of A. hygrophila fitted to the disc equation of Holling II. With the exception of the predatory function response of P. subpiraticus on 3rdinstar larvae of A. hygrophila,there were a significant correlation between predator and host prey that were fitted by the disc equation of Holling II. The maximum theoretical number of eggs, 1stinsar and 2ndinsar larvae of A. hygrophila captured by O. sertatus,P. subpiraticus and P. japonica per day was 10.9,6.2 and 5.6 eggs,17.1,35.8 and 10.4 1stinsar larvae,and 6.6,11.2 and 2.9 2ndinsar larvae,respectively. The maximum theoretical number of 3rdinsar larvae of A. hygrophila captured by O. sertatus and P. subpiraticus was 12.3 and 1.1 larvae, respectively. The results of our present study suggest that the predation of predators can decrease the population density of A. hygrophila,which weakens the control efficiency of A. hygrophila on A. philoxeroides in the field. Therefore,the predators are an important biotic stress factor that affects survival and development of A. hygrophila in the field. Another further study should focus on how the biocontrol efficiency of A. philoxeroides are enhanced via increasing the population density of A. hygrophila in the field.

Spider toxins comprising disulfide‐rich and linear amphipathic domains: a new class of molecules identified in the lynx spider Oxyopes takobius

In addition to the conventional neurotoxins and cytotoxins, venom of the lynx spider Oxyopes takobius was found to contain two-domain modular toxins named spiderines: OtTx1a, 1b, 2a and 2b. These toxins show both insecticidal activity (a median lethal dose against flesh fly larvae of 75 μg·g(-1)) and potent antimicrobial effects (minimal inhibitory concentrations in the range 0.1-10 μm). Full sequences of the purified spiderines were established by a combination of Edman degradation, mass spectrometry and cDNA cloning. They are relatively large molecules (~ 110 residues, 12.0-12.5 kDa) and consist of two distinct modules separated by a short linker. The N-terminal part (~ 40 residues) contains no cysteine residues, is highly cationic, forms amphipathic α-helical structures in a membrane-mimicking environment, and shows potent cytolytic effects on cells of various origins. The C-terminal part (~ 60 residues) is disulfide-rich (five S-S bonds), and contains the inhibitor cystine knot (ICK/knottin) signature. The N-terminal part of spiderines is very similar to linear cytotoxic peptides found in various organisms, whereas the C-terminal part corresponds to the usual spider neurotoxins. We synthesized the modules of OtTx1a and compared their activity to that of full-length mature toxin produced recombinantly, highlighting the importance of the N-terminal part, which retained full-length toxin activity in both insecticidal and antimicrobial assays. The unique structure of spiderines completes the range of two-domain spider toxins.

5S ribosomal DNA cluster of a lynx spider Oxyopes sertatus includes a histone H2B-like gene in the spacer region (NTS)

5S ribosomal DNA cluster of a lynx spider Oxyopes sertatus includes a histone H2B-like gene in the spacer region (NTS)

Novel lynx spider toxin shares common molecular architecture with defense peptides from frog skin

A unique 30-residue cationic peptide oxyopinin 4a (Oxt 4a) was identified in the venom of the lynx spider Oxyopes takobius (Oxyopidae). Oxt 4a contains a single N-terminally located disulfide bond, Cys4-Cys10, and is structurally different from any spider toxin studied so far. According to NMR findings, the peptide is disordered in water, but assumes a peculiar torpedo-like structure in detergent micelles. It features a C-terminal amphipathic α-helical segment (body; residues 12-25) and an N-terminal disulfide-stabilized loop (head; residues 1-11), and has an unusually high density of positive charge in the head region. Synthetic Oxt 4a was produced and shown to possess strong and broad-spectrum cytolytic and antimicrobial activity. cDNA cloning showed that the peptide is synthesized in the form of a conventional prepropeptide with an acidic prosequence. Unlike other arachnid toxins, Oxt 4a exhibits striking similarity with defense peptides from the skin of ranid frogs that contain the so-called Rana-box motif (a C-terminal disulfide-enclosed loop). Parallelism or convergence is apparent on several levels: the structure, function and biosynthesis of a lynx spider toxin are mirrored by those of Rana-box peptides from frogs.

Biochemical characterization of cysteine-rich peptides from Oxyopes sp. venom that block calcium ion channels

Oxytoxins (OxyTx1 and OxyTx2) are disulfide-rich peptides isolated from the venom of the spider Oxyopes lineatus that block voltage-sensitive calcium ion channels (VSCCs). OxyTx1 was identified previously and isolated from the related spider Oxyopes kitabensis; however, its pharmacology was unknown. OxyTx1 and OxyTx2 contain 69 and 55 amino acid residues with molecular masses of 8058.2 and 6175.2 Da, respectively. Oxytoxins contain five disulfide bridges, are amidated at their C-terminus, antagonize P/Q-, N- or L-type VSCCs, and have low amino acid identity to known VSCC blockers from arthropod venoms. OxyTx1 is not specific for VSCCs subtypes when compared to the classical P/Q-type blocker ω-AgaIVA, but OxyTx1 has higher paralytic activity towards Spodoptera litura larvae. Because of their structural and biochemical characteristics OxyTx1 and OxyTx2 may represent a new family of insecticidal peptides.

Natural prey of the lynx spider <i>Oxyopes lineatus</i> (Araneae: Oxyopidae)

The natural prey of the lynx spider Oxyopes lineatus Latreille, 1806 was studied in a meadow in the subtropical zone of Azerbaijan. The percentage of specimens of O. lineatus found while feeding was low (4.3%). Spiders were observed feeding both day and night. The investigation has shown that O. lineatus is a polyphagous predator feeding on a wide range of arthropods, with representatives of nine arthropod orders found in its diet. The primary food of O. lineatus was Diptera, Hymenoptera, and Homoptera, which collectively made up about three quarters of all prey. Worker ants constituted about 20% of the diet suggesting that O. lineatus is a myrmecophagic spider. The length of prey killed by O. lineatus ranged between 0.50 and 8.50 mm (mean 2.72 mm), varying from 12.1 to 171.4% (mean 61.4%) of the length of their captors. The most frequently captured prey were arthropods not exceeding the length of the spiders (87.5%).

The effect of binding of spider-derived antimicrobial peptides, oxyopinins, on lipid membranes

Oxyopinins (Oxki1 and Oxki2) are antimicrobial peptides isolated from the crude venom of the wolf spider Oxyopes kitabensis. The effect of oxyopinins on lipid bilayers was investigated using high-sensitivity titration calorimetry and 31P solid-state NMR spectroscopy. High-sensitivity titration calorimetry experiments showed that the binding of oxyopinins was exothermic, and the binding enthalpies (Δ H) to 1-palmitoyl-2-oleoyl- sn-glycero-3-phosphatidylcholine (POPC) small unilamellar vesicles (SUVs) were − 18.1 kcal/mol and − 15.0 kcal/mol for Oxki1 and Oxki2, respectively, and peptide partition coefficient ( K p) was found to be 3.9 × 10 3 M − 1 . 31P NMR spectra of 1,2-dielaidoyl- sn-glycero-3-phosphoethanolamine (DEPE) membranes in the presence of oxyopinins indicated that they induced a positive curvature in lipid bilayers. The induced positive curvature was stronger in the presence of Oxki2 than in the presence of Oxki1. 31P NMR spectra of phosphaditylcholine (PC) membranes in the presence of Oxki2 showed that Oxki2 produced micellization of membranes at low peptide concentrations, but unsaturated PC membranes or acidic phospholipids prevented micellization from occurring. Furthermore, 31P NMR spectra using membrane lipids from E. coli suggested that Oxki1 was more disruptive to bacterial membranes than Oxki2. These results strongly correlate to the known biological activity of the oxyopinins.

Oxyopinins, Large Amphipathic Peptides Isolated from the Venom of the Wolf Spider Oxyopes kitabensis with Cytolytic Properties and Positive Insecticidal Cooperativity with Spider Neurotoxins

Five amphipathic peptides with antimicrobial, hemolytic, and insecticidal activity were isolated from the crude venom of the wolf spider Oxyopes kitabensis. The peptides, named oxyopinins, are the largest linear cationic amphipathic peptides from the venom of a spider that have been chemically characterized at present. According to their primary structure Oxyopinin 1 is composed of 48 amino acid residues showing extended sequence similarity to the ant insecticidal peptide ponericinL2 and to the frog antimicrobial peptide dermaseptin. Oxyopinins 2a, 2b, 2c, and 2d have highly similar sequences. At least 27 out of 37 amino acid residues are conserved. They also show a segment of sequence similar to ponericinL2. Circular dichroism analyses showed that the secondary structure of the five peptides is essentially alpha-helical. Oxyopinins showed disrupting activities toward both biological membranes and artificial vesicles, particularly to those rich in phosphatidylcholine. Electrophysiological recordings performed on insect cells (Sf9) showed that the oxyopinins produce a drastic reduction of cell membrane resistance by opening non-selective ion channels. Additionally, a new paralytic neurotoxin named Oxytoxin 1 was purified from the same spider venom. It contains 69 amino acid residue cross-linked by five disulfide bridges. Application of mixtures containing oxyopinins and Oxytoxin 1 to insect larvae showed a potentiation phenomenon, by which an increase lethality effect is observed. These results suggest that the linear amphipathic peptides in spider venoms and neuropeptides cooperate to capture insects efficiently.

Comparison of the Feeding Niche of Polyphagous Insectivores (Araneae) in a Texas Cotton Plantation: Estimates of Niche Breadth and Overlap

The feeding niches of 10 spider species that are polyphagous insectivores were compared by computing coefficients of niche breadth and niche overlap. The study is based on predation evidence from an insecticide-free cotton plantation in east Texas. All overlap values were <1.00 (range, 0.08–0.94), which indicates that each spider species has its own feeding niche in the cotton agroecosystem. Diet breadth, that is inversely related to feeding specialization, was computed for each species. The highest value was approximately five times higher than the minimum, which indicates considerable differences between species in feeding specialization. Diet breadth values indicate that large web weavers exhibited a less specialized feeding behavior (relatively broad feeding niche) compared with small web weavers (narrow feeding niche). Prey specialists in this study concentrated on either aphids or fire ants as a primary food source. The nonweb-building spider Oxyopes salticus Hentz, which actively searches the cotton plant for prey (up to=6 mm maximum length), showed the highest diet breadth value (broad feeding niche) under the conditions of this experiment. This abundant species, which is considered a highly beneficial biocontrol agent of smaller cotton pests, shows high flexibility in its foraging patterns.