CSTX-1, a toxin from the venom of the hunting spider Cupiennius salei, is a selective blocker of L-type calcium channels in mammalian neurons

The inhibitor cystine-knot motif identified in the structure of CSTX-1 from Cupiennius salei venom suggests that this toxin may act as a blocker of ion channels. Whole-cell patch-clamp experiments performed on cockroach neurons revealed that CSTX-1 produced a slow voltage-independent block of both mid/low- (M-LVA) and high-voltage-activated (HVA) insect Ca(v) channels. Since C. salei venom affects both insect as well as rodent species, we investigated whether Ca(v) channel currents of rat neurons are also inhibited by CSTX-1. CSTX-1 blocked rat neuronal L-type, but no other types of HVA Ca(v) channels, and failed to modulate LVA Ca(v) channel currents. Using neuroendocrine GH3 and GH4 cells, CSTX-1 produced a rapid voltage-independent block of L-type Ca(v) channel currents. The concentration-response curve was biphasic in GH4 neurons and the subnanomolar IC(50) values were at least 1000-fold lower than in GH3 cells. L-type Ca(v) channel currents of skeletal muscle myoballs and other voltage-gated ion currents of rat neurons, such as I(Na(v)) or I(K(v)) were not affected by CSTX-1. The high potency and selectivity of CSTX-1 for a subset of L-type channels in mammalian neurons may enable the toxin to be used as a molecular tool for the investigation of this family of Ca(v) channels.

Solution structure and interaction of cupiennin 1a, a spider venom peptide, with phospholipid bilayers

The solution structure of cupiennin 1a, a 35 residue, basic antibacterial peptide isolated from the venom of the spider Cupiennius salei, has been determined by nuclear magnetic resonance (NMR) spectroscopy. The peptide was found to adopt a helix−hinge−helix structure in a membrane mimicking solvent. The hinge may play a role in allowing the amphipathic N-terminal helix and polar C-terminal helix to orient independently upon membrane binding, in order to achieve maximal antibacterial efficacy. Solid-state 31P and 2H NMR was used to further study the effects of cupiennin 1a on the dynamic properties of lipid membranes, using zwitterionic chain deuterated dimyristoylphosphatidylcholine (d54-DMPC) and anionic dimyristoylphosphatidylglycerol (DMPG) multilamellar vesicles. In d54-DMPC alone, cupiennin 1a caused a decrease in the 31P chemical shift anisotropy, indicating some interaction with the lipid head groups, and a decrease in order over the entire acyl chain. In contrast, for the mixed (d54-DMPC/DMPG) lipid system cupiennin 1a appeared to induce lateral separation of the two lipids as evidenced by the 31P spectra, in which the peptide preferentially interacted with DMPG. Little effect was observed on the deuterated acyl chain order parameters in the d54-DMPC/DMPG model membranes. Furthermore, 31P NMR relaxation measurements confirmed a differential effect on the lipid motions depending upon the membrane composition. Therefore, subtle differences are likely in the mechanism by which cupiennin 1a causes membrane lysis in either prokaryotic or eukaryotic cells, and may explain the specific spectrum of activity.

Cupiennin 1a, an antimicrobial peptide from the venom of the neotropical wandering spider Cupiennius salei, also inhibits the formation of nitric oxide by neuronal nitric oxide synthase

Cupiennin 1a (GFGALFKFLAKKVAKTVAKQAAKQGAKYVVNKQME-NH2) is a potent venom component of the spider Cupiennius salei. Cupiennin 1a shows multifaceted activity. In addition to known antimicrobial and cytolytic properties, cupiennin 1a inhibits the formation of nitric oxide by neuronal nitric oxide synthase at an IC50 concentration of 1.3 +/- 0.3 microM. This is the first report of neuronal nitric oxide synthase inhibition by a component of a spider venom. The mechanism by which cupiennin 1a inhibits neuronal nitric oxide synthase involves complexation with the regulatory protein calcium calmodulin. This is demonstrated by chemical shift changes that occur in the heteronuclear single quantum coherence spectrum of 15N-labelled calcium calmodulin upon addition of cupiennin 1a. The NMR data indicate strong binding within a complex of 1 : 1 stoichiometry.

Hypervigilance-avoidance pattern in spider phobia

Cognitive-motivational theories of phobias propose that patients' behavior is characterized by a hypervigilance-avoidance pattern. This implies that phobics initially direct their attention towards fear-relevant stimuli, followed by avoidance that is thought to prevent objective evaluation and habituation. However, previous experiments with highly anxious individuals confirmed initial hypervigilance and yet failed to show subsequent avoidance. In the present study, we administered a visual task in spider phobics and controls, requiring participants to search for spiders. Analyzing eye movements during visual exploration allowed the examination of spatial as well as temporal aspects of phobic behavior. Confirming the hypervigilance-avoidance hypothesis as a whole, our results showed that, relative to controls, phobics detected spiders faster, fixated closer to spiders during the initial search phase and fixated further from spiders subsequently.

The new Australasian goblin spider genus Prethopalpus (Araneae, Oonopidae)

The new goblin spider genus Prethopalpus is restricted to the Australasian tropics, from the lower Himalayan Mountains in Nepal and India to the Malaysian Peninsula, Indonesia, Papua New Guinea, and Australia. Prethopalpus contains those species with a swollen palpal patella, which is one to two times the size of the femur, together with a cymbium and bulb that is usually separated, although it is largely fused in four species. The type species Opopaea fosuma Burger et al. from Sumatra, and Camptoscaphiella infernalis Harvey and Edward from Western Australia are newly transferred to Prethopalpus. The genus consists of 41 species of which 39 are newly described: P. ilam Baehr (♂, ♀) from Nepal; P. khasi Baehr (♂), P. madurai Baehr (♂), P. mahanadi Baehr (♂, ♀), and P. meghalaya Baehr (♂, ♀) from India; P. bali Baehr (♂), P. bellicosus Baehr and Thoma (♂, ♀), P. brunei Baehr (♂, ♀), P. deelemanae Baehr and Thoma (♂), P. java Baehr (♂, ♀), P. kranzae Baehr (♂), P. kropfi Baehr (♂, ♀), P. leuser Baehr (♂, ♀), P. magnocularis Baehr and Thoma (♂), P. pahang Baehr (♂), P. perak Baehr (♂, ♀), P. sabah Baehr (♂, ♀), P. sarawak Baehr (♂), P. schwendingeri Baehr (♂, ♀), and P. utara Baehr (♂, ♀) from Indonesia and Malaysia; and P. alexanderi Baehr and Harvey (♂), P. attenboroughi Baehr and Harvey (♂), P. blosfeldsorum Baehr and Harvey (♂), P. boltoni Baehr and Harvey (♂, ♀), P. callani Baehr and Harvey (♂, ♀), P. cooperi Baehr and Harvey (♂), P. eberhardi Baehr and Harvey (♂, ♀), P. framenaui Baehr and Harvey (♂, ♀), P. humphreysi Baehr and Harvey (♂, ♀), P. kintyre Baehr and Harvey (♂), P. scanloni Baehr and Harvey (♂), P. pearsoni Baehr and Harvey (♂), P. julianneae Baehr and Harvey (♂), P. maini Baehr and Harvey (♂, ♀), P. marionae Baehr and Harvey (♂, ♀), P. platnicki Baehr and Harvey (♂, ♀), P. oneillae Baehr and Harvey (♂), P. rawlinsoni Baehr and Harvey (♂), and P. tropicus Baehr and Harvey (♂, ♀) from Australia and Papua New Guinea. Three separate keys to species from different geographical regions are provided. Most species are recorded from single locations and only three species are more widely distributed. A significant radiation of blind troglobites comprising 14 species living in subterranean ecosystems in Western Australia is discussed. These include several species that lack abdominal scuta, a feature previously used to define subfamilies of Oonopidae.

A two year study of verified spider bites in Switzerland and a review of the European spider bite literature

During a two-year study, all spider bites recorded by Swiss primary care physicians were reported to the Swiss Toxicological Information Centre and all collected spiders were identified. A total of 14 verified spider bites were recorded, involving five species from four families: Zoropsis spinimana (five cases), Cheiracanthium punctorium (four cases), Tegenaria atrica (three cases) and one case of Malthonica ferruginea (¼ Tegenaria ferruginea) (both Agelenidae), and one case of Amaurobius ferox (Amaurobiidae). The bites of all spider species produced relatively mild symptoms. Local symptoms such as moderate to severe pain, circumscribed swelling and redness were the only effects in most cases. Systemic symptoms were rare. There was complete recovery in all cases and all lesions healed completely without further damage or secondary disorders. Following a review of the European spider bite literature, the number of spider species capable of biting humans in Europe is considered to be much larger than could be concluded from this study. Most spider bites are restricted to species living synanthropically, thus promoted by climate and habitat change. The annual frequency of spider bites in Switzerland is estimated at 10 – 100 bites per million inhabitants, but this is predicted to increase due to the continuous arrival of new alien species, many of which have a high potential to establish in urban areas

N-terminal aromatic residues closely impact the cytolytic activity of cupiennin 1a, a major spider venom peptide

Cupiennins are small cationic a-helical peptides from the venom of the ctenid spider Cupiennius salei which are characterized by high bactericidal as well as hemolytic activities. To gain insight into the determinants responsible for the broad cytolytic activities, two analogues of cupiennin 1a with different N-terminal hydrophobicities were designed. The insecticidal, bactericidal and hemolytic activities of these analogues were assayed and compared to the native peptide. Specifically, substitution of two N-terminal Phe residues by Ala results in less pronounced insecticidal and cytolytic activity, whereas a substitution by Lys reduces strongly its bactericidal activity and completely diminishes its hemolytic activity up to very high tested concentrations. Biophysical analyses of peptide/bilayer membrane interactions point to distinct interactions of the analogues with lipid bilayers, and dependence upon membrane surface charge. Indeed, we find that lower hemolytic activity was correlated with less surface association of the analogues. In contrast, our data indicate that the reduced bactericidal activity of the two cupiennin 1a analogues likely correspond to greater bilayer-surface localization of the peptides. Overall, ultimate insertion and destruction of the host cell membrane is highly dependent on the presence of Phe-2 and Phe-6 (Cu 1a) or Leu-6 (Cu 2a) in the N-terminal sequences of native cupiennins.