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At least 847 records · Page 47Linked to original sources
PubMed2002

Loxosceles spider venom induces metalloproteinase mediated cleavage of MCP/CD46 and MHCI and induces protection against C-mediated lysis.

We have recently shown that sphingomyelinase D toxins from the spider Loxosceles intermedia induce Complement (C) -dependent haemolysis of autologous erythrocytes by the induction of cleavage of cell-surface glycophorins through activation of a membrane-bound metalloproteinase. The aim of this study was to investigate the effects of these toxins on C-regulator expression and the C-resistance of nucleated cells. Cells were incubated with Loxosceles venom/toxins and the expression of C-regulators was assessed by flow cytometry. A reduced expression of membrane co-factor protein (MCP) was observed, while expression of decay-accelerating factor (DAF) and CD59 was not affected. Analysis of other cell-surface molecules showed a reduced expression of major histocompatibility complex I (MHCI). Western blotting showed that a truncated form of MCP was released into the supernatant. Release could be prevented by inhibitors of metalloproteinases of the adamalysin family but not by inhibitors specific for matrix metalloproteinases. Cleavage of MCP was induced close to or within the membrane as demonstrated by the cleavage of transmembrane chimeras of CD59 and MCP. Although the venom/toxins induced a release of MCP, the C-susceptibility was decreased. The mechanism of this induction of resistance may involve a change in membrane fluidity induced by the sphingomyelinase activity of the toxin/venom and/or involvement of membrane-bound proteases. The soluble forms of MCP found in tissues and body under pathological conditions like cancer and autoimmune diseases may be released by a similar mechanism. The identity of the metalloproteinase(s) activated by the spider venom and the role in pathology of Loxoscelism remains to be established.

Amino Acid Sequence↗
PubMed2000

Ultrastructural and molecular identification of a Wolbachia endosymbiont in a spider, Nephila clavata.

Wolbachia-like bacteria were observed in the egg cells of golden orb-weaving spider, Nephila clavata, by means of transmission electron microscopy. The bacteria exhibited the typical morphology of Wolbachia, including three enveloping membranes. Based on the amplification and sequencing of partial 16S rDNA and ftsZ gene, the bacteria were identified as Wolbachia, intracellular, transovarially inherited alpha-proteobacteria in invertebrates. Phylogenetic analysis based on 16S rDNA and ftsZ gene sequences invariably indicated that the intracellular bacteria from N. clavata belonged to group A Wolbachia, which were found only from insects. Clustering of Wolbachia from N. clavata with group A Wolbachia indicates that the bacteria were probably transferred horizontally between insects and the spider.

Animals↗
PubMed2001

Deep molecular divergence in the absence of morphological and ecological change in the Californian coastal dune endemic trapdoor spider Aptostichus simus.

Aptostichus simus is a trapdoor spider endemic to the coastal dunes of central and southern California and, on morphological grounds, is recognized as a single species. Mitochondrial DNA 16S rRNA sequences demonstrate that most populations are fixed for the same haplotype and that the population haplotypes from San Diego County, Los Angeles County, Santa Rosa Island, and Monterey County are extremely divergent (6-12%), with estimated separation times ranging from 2 to 6 million years. A statistical cluster analysis of morphological features demonstrates that this genetic divergence is not reflected in anatomical features that might signify ecological differentiation among these lineages. The species status of these divergent populations of A. simus depends upon the species concept utilized. If a time-limited genealogical perspective is employed, A. simus would be separated at the base into two genetically distinct species. This study suggests that species concepts based on morphological distinctiveness, in spider groups with limited dispersal capabilities, probably underestimate true evolutionary diversity.

Animals↗
PubMed2001

Conservation genetics of peripheral populations of the mygalomorph spider Atypus affinis (Atypidae) in northern Europe.

Genetic diversity and differentiation were studied in peripheral populations of the recently rediscovered purse-web spider Atypus affinis in Denmark and Sweden using allozyme electrophoresis. Because of the very narrow environmental niche exploited by this species, only a limited number of potential habitats are available. Furthermore, fragmentation has reduced the number and size of potential habitats within the last century. The level of genetic diversity in A. affinis was intermediate compared with other nonsocial spiders, but low compared with invertebrates in general. Significant genetic differentiation was found within distances of only 1-10 km with FST estimates ranging from 0.020 to 0.075. Within distances of 30-60 km FST ranged from 0.081 to 0.312. Hierarchical FST revealed that genetic variability was partitioned at 89.8% within populations, 9.5% among populations within regions and only 0.7% among the four main regions in Denmark and Sweden. Comparing the result of the genetic analysis with the life history of A. affinis, it is concluded that the level of successful dispersal is low, and that the species has not recently reinvaded northern Europe but prevailed undiscovered for several decades. Finally, it is suggested that the genetic scenario found for A. affinis might represent that for a wide range of other arthropods with similar life history characteristics.

Animals↗
PubMed2002

Variations in receptor site-3 on rat brain and insect sodium channels highlighted by binding of a funnel-web spider delta-atracotoxin.

Delta-atracotoxins (delta-ACTXs) from Australian funnel-web spiders differ structurally from scorpion alpha-toxins (Sc(alpha)Tx) but similarly slow sodium current inactivation and compete for their binding to sodium channels at receptor site-3. Characterization of the binding of 125I-labelled delta-ACTX-Hv1a to various sodium channels reveals a decrease in affinity for depolarized (0 mV; Kd=6.5 +/- 1.4 nm) vs.polarized (-55 mV; Kd=0.6 +/- 0.2 nm) rat brain synaptosomes. The increased Kd under depolarized conditions correlates with a 4.3-fold reduction in the association rate and a 1.8-increase in the dissociation rate. In comparison, Sc(alpha)Tx binding affinity decreased 33-fold under depolarized conditions due to a 48-fold reduction in the association rate. The binding of 125I-labelled delta-ACTX-Hv1a to rat brain synaptosomes is inhibited competitively by classical Sc(alpha)Txs and allosterically by brevetoxin-1, similar to Sc(alpha)Tx binding. However, in contrast with classical Sc(alpha)Txs, 125I-labelled delta-ACTX-Hv1a binds with high affinity to cockroach Na+ channels (Kd=0.42 +/- 0.1 nm) and is displaced by the Sc(alpha)Tx, Lqh(alpha)IT, a well-defined ligand of insect sodium channel receptor site-3. However, delta-ACTX-Hv1a exhibits a surprisingly low binding affinity to locust sodium channels. Thus, unlike Sc(alpha)Txs, which are capable of differentiating between mammalian and insect sodium channels, delta-ACTXs differentiate between various insect sodium channels but bind with similar high affinity to rat brain and cockroach channels. Structural comparison of delta-ACTX-Hv1a to Sc(alpha)Txs suggests a similar putative bioactive surface but a 'slimmer' overall shape of the spider toxin. A slimmer shape may ease the interaction with the cockroach and mammalian receptor site-3 and facilitate its association with different conformations of the rat brain receptor, correlated with closed/open and slow-inactivated channel states.

Allosteric Regulation↗
PubMed2003

Subunit sequences of the 4 x 6-mer hemocyanin from the golden orb-web spider, Nephila inaurata.

The transport of oxygen in the hemolymph of many arthropod and mollusc species is mediated by large copper-proteins that are referred to as hemocyanins. Arthropod hemocyanins are composed of hexamers and oligomers of hexamers. Arachnid hemocyanins usually form 4 x 6-mers consisting of seven distinct subunit types (termed a-g), although in some spider taxa deviations from this standard scheme have been observed. Applying immunological and electrophoretic methods, six distinct hemocyanin subunits were identified in the red-legged golden orb-web spider Nephila inaurata madagascariensis (Araneae: Tetragnathidae). The complete cDNA sequences of six subunits were obtained that corresponded to a-, b-, d-, e-, f- and g-type subunits. No evidence for a c-type subunit was found in this species. The inclusion of the N. inaurata hemocyanins in a multiple alignment of the arthropod hemocyanins and the application of the Bayesian method of phylogenetic inference allow, for the first time, a solid reconstruction of the intramolecular evolution of the chelicerate hemocyanin subunits. The branch leading to subunit a diverged first, followed by the common branch of the dimer-forming b and c subunits, while subunits d and f, as well as subunits e and g form common branches. Assuming a clock-like evolution of the chelicerate hemocyanins, a timescale for the evolution of the Chelicerata was obtained that agrees with the fossil record.

Amino Acid Sequence↗
PubMed1999

Isolation, amino acid sequence and functional assays of SGTx1. The first toxin purified from the venom of the spider scodra griseipes.

A new toxin (SGTx1) was purified from the venom of the spider Scodra griseipes by a combination of gel filtration and reverse-phase chromatography. The complete amino acid sequence of SGTx1, TCRYLFGGCKTTADCCKHLACRSDGKYCAWDGTF, was established by direct automated Edman degradation, and is in perfect agreement with the molecular mass of 3775 Da found by mass spectrometry. The primary structure of SGTx1 exhibited sequence identity with other spider toxins such as hanatoxin (76%), TxP5 toxin (32%) and huwentoxin (26%). The six cysteines in the sequence suggested three disulfide bridges, the presence of which was demonstrated by mass spectrometry after dithiothreitol reduction. Analysis of secondary structure using circular dichroism spectrometry yielded more than 50% beta-sheet and about 15-20% beta-turn. The extent of the beta-content and the presence of disulfide bridges suggest a structure of interconnected beta-strands. In addition, a study of membrane/toxin interactions was carried out by reconstitution in planar lipid bilayers and by antibacterial assays. SGTx1 displays moderate pore-forming ability (conductance of about 100 pS in 1 M NaCl), but antibacterial activity was not observed against Gram-positive or Gram-negative strains. As a preliminary assay, the activity of SGTx1 was investigating using electrophysiological measurements. At 0.15 microM, SGTx1 reversibly inhibits more than 40% of outward potassium currents in rat cerebellum granular cells. This result is reminiscent with the effect described for hanatoxin extracted from the venom of Grammostola spatulata.

Amino Acid Sequence↗
PubMed2001

A controlled trial of topical nitroglycerin in a New Zealand white rabbit model of brown recluse spider envenomation.

STUDY OBJECTIVES: Topical nitroglycerin has been reported to prevent skin necrosis from brown recluse spider bites, but this has never been scientifically tested. This study attempts to assess the effects of topical nitroglycerin on experimental Loxosceles reclusa envenomations. METHODS: We performed a randomized, blinded, controlled study in an animal care facility. Twenty-four New Zealand white rabbits were experimentally envenomated by means of subcutaneous injection with 20 microg of brown recluse spider venom. Rabbits were randomized to 1 of 2 experimental groups. The treatment group received 1 in of 2% topical nitroglycerin ointment every 6 hours for 3 days applied directly to the envenomation site. The control group received the vehicle without nitroglycerin. Gross examination of the lesions and measurements of the areas of the lesions were made daily. Creatine phosphokinase (CPK), blood urea nitrogen, creatinine, hemoglobin, and hematocrit levels were measured on days 0, 5, and 10. Lesions were excised after 10 days and examined by a blinded pathologist, who measured the area of necrosis and quantified inflammation and edema using a standard wound-healing score. For all values, mean values plus SD were determined. All comparisons made over multiple time points were assessed for significance by using a repeated-measures analysis of variance followed by Fisher least significant difference and Scheffé post hoc comparisons. A P value of.05 or less was used to determine significance. The Student's t test was used to compare the means of single measures. Significance was determined by using 95% confidence intervals. Comparisons of total area of necrosis were made with the nonparametric Mann-Whitney U test because of the heavy positive skew of the data. RESULTS: Skin necrosis developed in all animals. Mean values of the lesion area were not significantly different over time between the 2 groups of animals. At day 10, the median area of necrosis was 22.3 cm2 for the treatment group and 15.4 cm2 for the control group (P =.12). The inflammation score was 3.33+/-0.78 for the treatment group and 2.79+/-1.29 for the control group (P < .01). The edema score was 1.25+/-1.28 for the treatment group and 0.98+/-1.10 for the control group (not significantly different). CPK levels increased dramatically in both groups, with the greatest increase in the treatment group. In both groups hemoglobin and hematocrit levels decreased significantly, whereas WBC counts and platelet counts increased significantly, without significant differences between the 2 groups. CONCLUSION: At the dose used in this experiment, topical nitroglycerin did not prevent skin necrosis, increased inflammation score, and increased serum CPK levels. The results of this study do not support the use of topical nitroglycerin in the treatment of L reclusa envenomation and suggest that systemic toxicity could be increased.

Administration, Cutaneous↗
PubMed2006

Novel nanocomposites from spider silk-silica fusion (chimeric) proteins.

Silica skeletal architectures in diatoms are characterized by remarkable morphological and nanostructural details. Silk proteins from spiders and silkworms form strong and intricate self-assembling fibrous biomaterials in nature. We combined the features of silk with biosilica through the design, synthesis, and characterization of a novel family of chimeric proteins for subsequent use in model materials forming reactions. The domains from the major ampullate spidroin 1 (MaSp1) protein of Nephila clavipes spider dragline silk provide control over structural and morphological details because it can be self-assembled through diverse processing methods including film casting and fiber electrospinning. Biosilica nanostructures in diatoms are formed in aqueous ambient conditions at neutral pH and low temperatures. The R5 peptide derived from the silaffin protein of Cylindrotheca fusiformis induces and regulates silica precipitation in the chimeric protein designs under similar ambient conditions. Whereas mineralization reactions performed in the presence of R5 peptide alone form silica particles with a size distribution of 0.5-10 microm in diameter, reactions performed in the presence of the new fusion proteins generate nanocomposite materials containing silica particles with a narrower size distribution of 0.5-2 microm in diameter. Furthermore, we demonstrate that composite morphology and structure could be regulated by controlling processing conditions to produce films and fibers. These results suggest that the chimeric protein provides new options for processing and control over silica particle sizes, important benefits for biomedical and specialty materials, particularly in light of the all aqueous processing and the nanocomposite features of these new materials.

Amino Acid Sequence↗
PubMed2003

Subadult experience influences adult mate choice in an arthropod: exposed female wolf spiders prefer males of a familiar phenotype.

Current sexual selection theory proposes several potential mechanisms driving the evolution of female mating preferences, few of which involve social interactions. Although vertebrate examples of socially influenced mating preferences do exist, the invertebrate examples are virtually nonexistent. Here I demonstrate that the mating preferences of female wolf spiders can be acquired through exposure as subadults to unrelated, sexually active adult males. I first conducted exposure trials during which subadult females of the wolf spider Schizocosa uetzi were allowed to interact with mature males of an experimentally manipulated phenotype (either black or brown forelegs). After maturation, these previously exposed females were paired with a male of either a familiar or unfamiliar manipulated phenotype for mate-choice trials. Subadult females that were exposed to directed courtship by mature males of a particular morphological phenotype were subsequently more likely to mate with a male of a familiar phenotype as adults. Furthermore, females that were exposed as subadults were more likely, as adults, to cannibalize a courting male with an unfamiliar phenotype. Unexposed females did not distinguish between phenotypes in either mate choice or cannibalism frequency. These results suggest a previously uncharacterized mechanism influencing the origin of female mating preferences and ultimately the evolution of male traits: subadult experience. This study also stresses the potential importance of learning and memory on adult mate choice in an arthropod.

Animals↗
PubMed1984

Spider venoms inhibit L-glutamate binding to brain synaptic membrane receptors.

The venoms from three spider species, Araneus gemma, Neoscona arabesca, and Argiope aurantia, were shown to inhibit the high-affinity, sodium-independent L-glutamate-binding sites in rat brain synaptic membranes. The same three venoms caused concentration-dependent inhibition of the activity of the glutamate-binding glycoprotein purified from rat brain synaptic membranes. The venom milked from the glands of Araneus gemma was the most active inhibitor of L-glutamate binding, causing 60-80% inhibition of both synaptic membrane and purified protein binding activity at 0.01 unit. The inhibitory activity of this venom was associated with a single protein peak obtained from gel permeation chromatography of the venom. Finally, the effect of the venom from Araneus gemma on the synaptic membrane glutamate-binding sites was slowly reversible. These observations indicate that the spider venoms have a direct effect on the recognition sites for L-glutamic acid in brain synaptic membranes and that these sites are related to the physiologic glutamate receptors.

Animals↗
PubMed1990

Funnel-web spider venom and a toxin fraction block calcium current expressed from rat brain mRNA in Xenopus oocytes.

Injection of rat brain mRNA into Xenopus oocytes has been shown to induce a calcium current (ICa) that is insensitive to dihydropyridine and omega-conotoxin. We examined the effect of funnel-web spider venom on two aspects of this expressed ICa: (i) the calcium-activated chloride current [ICl(Ca)] and (ii) the currents carried by barium ions through calcium channels (IBa). In the presence of 1.8 mM extracellular calcium, ICl(Ca) tail current became detectable between -30 and -40 mV from a holding potential of -80 mV and reached a maximal amplitude between 0 and +10 mV. Total spider venom partially (83%) and reversibly blocked the calcium-activated chloride current without changing its voltage sensitivity. A chromatographic toxin fraction from the venom also blocked this current (64%). The venom had a minimal effect on INa and IK. Direct investigation of inward current mediated by calcium channels was carried out in high-barium solution. IBa had a higher threshold of activation (-30 to -20 mV) and reached its maximal amplitude at about +20 mV. Total venom or a partly purified chromatographic toxic fraction blocked IBa partially and reversibly without changing its current-voltage characteristics. Furthermore, the extent of the total venom block depended on the concentration of extracellular barium. Only 35% of the IBa was blocked in 60 mM Ba2+, whereas the block increased to 65% and 71%, respectively, for 40 and 20 mM Ba2+. On the basis of these results, we propose that the calcium channels expressed from rat brain mRNA in Xenopus oocytes is similar to the recently discovered P-type channels.

Animals↗
PubMed1990

Structure of a protein superfiber: spider dragline silk.

Spider major ampullate (dragline) silk is an extracellular fibrous protein with unique characteristics of strength and elasticity. The silk fiber has been proposed to consist of pseudocrystalline regions of antiparallel beta-sheet interspersed with elastic amorphous segments. The repetitive sequence of a fibroin protein from major ampullate silk of the spider Nephila clavipes was determined from a partial cDNA clone. The repeating unit is a maximum of 34 amino acids long and is not rigidly conserved. The repeat unit is composed of three different segments: (i) a 6 amino acid segment that is conserved in sequence but has deletions of 3 or 6 amino acids in many of the repeats; (ii) a 13 amino acid segment dominated by a polyalanine sequence of 5-7 residues; (iii) a 15 amino acid, highly conserved segment. The latter is predominantly a Gly-Gly-Xaa repeat with Xaa being alanine, tyrosine, leucine, or glutamine. The codon usage for this DNA is highly selective, avoiding the use of cytosine or guanine in the third position. A model for the physical properties of fiber formation, strength, and elasticity, based on this repetitive protein sequence, is presented.

Amino Acid Sequence↗
PubMed1993

A single amino acid determines the subunit-specific spider toxin block of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate/kainate receptor channels.

Joro spider toxin (JSTX) is one of the most potent antagonists of glutamatergic AMPA/KA (alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate/kainate) receptor channels in invertebrates and vertebrates. A differential blocking effect on certain types of glutamatergic synapses--e.g., parallel and climbing fiber synaptic inputs to rat cerebellar Purkinje neurons--has been shown by using a synthetic analog of the spider toxin. By investigating the molecular basis of the JSTX action on the recombinant AMPA/KA receptors GluR1-GluR4 and GluR6 expressed in Xenopus oocytes, we found that submicromolar concentrations of JSTX exert a subunit-specific block. Thus, receptor subunits forming a receptor channel with a linear current-voltage (I-V) relationship (GluR1/2, GluR2/3, and GluR6) were not affected, while receptor subunits with rectifying I-V relationships (GluR1, GluR3, GluR4, and GluR1/3) were reversibly blocked by JSTX. By using receptor-subunit mutants obtained by site-directed mutagenesis, we have identified a single amino acid position (glutamine in the proposed second transmembrane domain) that is critical for the JSTX block. Since this site has previously been shown to control the I-V relationship of the AMPA/KA receptor channel and to participate in the regulation of the channel's permeability for calcium ions, our findings suggest that JSTX binds close to the central pore region of the channel.

Amino Acid Sequence↗
PubMed1998

A conserved mode of head segmentation in arthropods revealed by the expression pattern of Hox genes in a spider.

Chelicerates constitute a basic arthropod group with fossil representatives from as early as the Cambrian period. Embryonic development and the subdivision of the segmented body region into a prosoma and an opisthosoma are very similar in all extant chelicerates. The mode of head segmentation, however, has long been controversial. Although all other arthropod groups show a subdivision of the head region into six segments, the chelicerates are thought to have the first antennal segment missing. To examine this problem on a molecular level, we have compared the expression pattern of Hox genes in the spider Cupiennius salei with the pattern known from insects. Surprisingly, we find that the anterior expression borders of the Hox genes are in the same register and the same relative segmental position as in Drosophila. This contradicts the view that the homologue of the first antennal segment is absent in the spider. Instead, our data suggest that the cheliceral segment is homologous to the first antennal segment and the pedipalpal segment is homologous to the second antennal (or intercalary) segment in arthropods. Our finding implies that chelicerates, myriapods, crustaceans, and insects share a single mode of head segmentation, reinforcing the argument for a monophyletic origin of the arthropods.

Animals↗
PubMed2004

Spider and bacterial sphingomyelinases D target cellular lysophosphatidic acid receptors by hydrolyzing lysophosphatidylcholine.

Bites by Loxosceles spiders can produce severe clinical symptoms, including dermonecrosis, thrombosis, vascular leakage, hemolysis, and persistent inflammation. The causative factor is a sphingomyelinase D (SMaseD) that cleaves sphingomyelin into choline and ceramide 1-phosphate. A similar enzyme, showing comparable bioactivity, is secreted by certain pathogenic corynebacteria and acts as a potent virulence factor. However, the molecular basis for SMaseD toxicity is not well understood, which hampers effective therapy. Here we show that the spider and bacterial SMases D hydrolyze albumin-bound lysophosphatidylcholine (LPC), but not sphingosylphosphorylcholine, with K(m) values ( approximately 20-40 microm) well below the normal LPC levels in blood. Thus, toxic SMases D have intrinsic lysophospholipase D activity toward LPC. LPC hydrolysis yields the lipid mediator lysophosphatidic acid (LPA), a known inducer of platelet aggregation, endothelial hyperpermeability, and pro-inflammatory responses. Introduction of LPA(1) receptor cDNA into LPA receptor-negative cells renders non-susceptible cells susceptible to SmaseD, but only in LPC-containing media. Degradation of circulating LPC to LPA with consequent activation of LPA receptors may have a previously unappreciated role in the pathophysiology of secreted SMases D.

Animals↗
PubMed2003

Speciation on a conveyor belt: sequential colonization of the hawaiian islands by Orsonwelles spiders (Araneae, Linyphiidae).

Spiders of the recently described linyphiid genus Orsonwelles (Araneae, Linyphiidae) are one of the most conspicuous groups of terrestrial arthropods of Hawaiian native forests. There are 13 known Orsonwelles species, and all are single- island endemics. This radiation provides an excellent example of insular gigantism. We reconstructed the cladistic relationships of Orsonwelles species using a combination of morphological and molecular characters (both mitochondrial and nuclear sequences) within a parsimony framework. We explored and quantified the contribution of different character partitions and their sensitivity to changes in the traditional parameters (gap, transition, and transversion costs). The character data show a strong phylogenetic signal, robust to parameter changes. The monophyly of the genus Orsonwelles is strongly supported. The parsimony analysis of all character evidence combined recovered a clade with of all the non-Kauai Orsonwelles species; the species from Kauai form a paraphyletic assemblage with respect to the latter former clade. The biogeographic pattern of the Hawaiian Orsonwelles species is consistent with colonization by island progression, but alternative explanations for our data exist. Although the geographic origin of the radiation remains unknown, it appears that the ancestral colonizing species arrived first on Kauai (or an older island). The ambiguity in the area cladogram (i.e., post-Oahu colonization) is not derived from conflicting or unresolved phylogenetic signal among Orsonwelles species but rather from the number of taxa on the youngest islands. Speciation in Orsonwelles occurred more often within islands (8 of the 12 cladogenic events) than between islands. A molecular clock was rejected for the sequence data. Divergence times were estimated by using the nonparametric rate smoothing method of Sanderson (1997, Mol. Biol. Evol. 14:1218-1231) and the available geological data for calibration. The results suggest that the oldest divergences of Orsonwelles spiders (on Kauai) go back about 4 million years.

Animals↗
PubMed1975

Ultraviolet and green receptors in principal eyes of jumping spiders.

Spectral sensitivities of cells in principal eyes of the jumping spider Phidippus reqius were measured using techniques of intracellular recording. Three types of cells were found. UV cells had peak sensitivities at 370 nm and were over 4 log units less sensitive at wavelengths longer than 460 nm. Green-sensitive cells had spectral sensitivities which were well fit by nomogram curves peaking at 532 nm. UV-green cells had dual peaks of sensitivity at about 370 and 525 nm, but the ratios of UV-to-green sensitivities varied over a 40: 1 range from cell to cell. Moreover, responses of UV-green cells to flashes of UV light were slower than to flashes of green light. Segregation of receptor types into the known layers of receptors in these eyes could not be shown. It is concluded that jumping spiders have the potential for dichromatic color vision.

Animals↗