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Masaaki Miyashita - One of the best experts on this subject based on the ideXlab platform.
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Structures of spider toxins: hydroxyindole-3-acetylpolyamines and a new generalized structure of type-E compounds obtained from the venom of the Joro spider, Nephila clavata.
Toxicon : official journal of the International Society on Toxinology, 1998Co-Authors: Miki Hisada, Masaaki Miyashita, Hiroshi Irie, Yasuhiro Itagaki, Tsuyoshi Fujita, Hideo Naoki, Terumi NakajimaAbstract:Facile structure determination of acylpolyamines, glutamatergic nerve blocker obtained from the venom of the Joro spider (Nephila clavata) was carried out with the use of μ-column LC/MS and high energy collision induced dissociation (CID) mass spectrometry. 6-hydroxyindole-3-acetyl was proposed previously as a putative partial structure, for the acyl moiety of hydroxyindole-type polyamines (NPTX-1∼6). The NMR data obtained for NPTX-6, NPTX-687 and hydroxyindole-3-acetic acid which was released by acid hydrolysis of Nephila clavata crude venom extracts proved that the lipophilic head is the 4-hydroxyindole-3-acetic acid. Various hydroxyindole-3-acetyl polyamines were found in N. clavata venom and characterized by mass spectrometry. As a result, type-E, a new class of generalized acylpolyamine structure was proposed in addition to the previously reported polyamine backbones type-A to -D.
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Total synthesis of NPTX-5 and NPTX-6, Joro spider (Nephila clavata) toxins having a unique putreanine trimer and putreanine tetramer acylpolyamine chain
Tetrahedron Letters, 1998Co-Authors: Hiroaki Saito, Terumi Nakajima, Masahiro Miyazawa, Yasuhiro Itagaki, Etsuko Yuri, Masaaki MiyashitaAbstract:Abstract The first total synthesis of NPTX-5 and NPTX-6, Joro spider ( Nephila clavata ) toxins having a 4-hydroxyindole nucleus and a unique putreanine trimer and tetramer acylpolyamine chain, respectively, has been achieved by the iterative use of a key azide compound.
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Total synthesis of Nephilatoxin-1 (NPTX-1), a Joro spider (Nephila clavata) toxin having a 4-hydroxyindole nucleus
Tetrahedron Letters, 1997Co-Authors: Masaaki Miyashita, Masayuki Matsushita, Hiroaki Saito, Masahiro Miyazawa, Yasuhiro Itagaki, Terumi NakajimaAbstract:Abstract The first total synthesis of Nephilatoxin-1 (NPTX-1), a Joro spider ( Nephila clavata ) toxin having a 4-hydroxyindole nucleus, has been achieved by using two key azide intermediates.
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TOTAL SYNTHESIS OF NephilaTOXIN-7 (NPTX-7), A NEW NEUROTOXIN OF JORO SPIDER (Nephila CLAVATA)
Tetrahedron Letters, 1995Co-Authors: Masayuki Matsushita, Takashi Toki, Hiroshi Irie, T. Kanemura, Susumi Hatakeyama, Masaaki MiyashitaAbstract:Abstract The first and highly efficient total synthesis of Nephilatoxin-7 (NPTX-7), a new neurotoxin of Joro spider ( Nephila clavata ), has been achieved by employing the azide strategy wherein the three characteristic polyamine components of the toxin, cadaverine and bis-putreanine, were efficiently constructed by the iterative use of key azide intermediates.
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An efficient synthesis of JSTX-3, a potent neurotoxin of Joro spider (Nephila clavata)
Tetrahedron, 1995Co-Authors: Masayuki Matsushita, Takashi Toki, Hiroshi Irie, T. Kanemura, Susumi Hatakeyama, Masaaki MiyashitaAbstract:Abstract JSTX-3 (Joro spider toxin-3) (1), a potent neurotoxin isolated from Joro spider ( Nephila clavata ), has been efficiently synthesized starting from 5-azido-l-N-Boc-pentylamine (11) via the convergent synthetic strategy in which the characteristic polyamine components of the toxin were effectively constructed by the use of two key azide intermediates.
Terumi Nakajima - One of the best experts on this subject based on the ideXlab platform.
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Total synthesis of NPTX-5 and NPTX-6, Joro spider (Nephila clavata) toxins having a unique putreanine trimer and putreanine tetramer acylpolyamine chain
Tetrahedron Letters, 1998Co-Authors: Hiroaki Saito, Terumi Nakajima, Masahiro Miyazawa, Yasuhiro Itagaki, Etsuko Yuri, Masaaki MiyashitaAbstract:Abstract The first total synthesis of NPTX-5 and NPTX-6, Joro spider ( Nephila clavata ) toxins having a 4-hydroxyindole nucleus and a unique putreanine trimer and tetramer acylpolyamine chain, respectively, has been achieved by the iterative use of a key azide compound.
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Structures of spider toxins: hydroxyindole-3-acetylpolyamines and a new generalized structure of type-E compounds obtained from the venom of the Joro spider, Nephila clavata.
Toxicon : official journal of the International Society on Toxinology, 1998Co-Authors: Miki Hisada, Masaaki Miyashita, Hiroshi Irie, Yasuhiro Itagaki, Tsuyoshi Fujita, Hideo Naoki, Terumi NakajimaAbstract:Facile structure determination of acylpolyamines, glutamatergic nerve blocker obtained from the venom of the Joro spider (Nephila clavata) was carried out with the use of μ-column LC/MS and high energy collision induced dissociation (CID) mass spectrometry. 6-hydroxyindole-3-acetyl was proposed previously as a putative partial structure, for the acyl moiety of hydroxyindole-type polyamines (NPTX-1∼6). The NMR data obtained for NPTX-6, NPTX-687 and hydroxyindole-3-acetic acid which was released by acid hydrolysis of Nephila clavata crude venom extracts proved that the lipophilic head is the 4-hydroxyindole-3-acetic acid. Various hydroxyindole-3-acetyl polyamines were found in N. clavata venom and characterized by mass spectrometry. As a result, type-E, a new class of generalized acylpolyamine structure was proposed in addition to the previously reported polyamine backbones type-A to -D.
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Total synthesis of Nephilatoxin-1 (NPTX-1), a Joro spider (Nephila clavata) toxin having a 4-hydroxyindole nucleus
Tetrahedron Letters, 1997Co-Authors: Masaaki Miyashita, Masayuki Matsushita, Hiroaki Saito, Masahiro Miyazawa, Yasuhiro Itagaki, Terumi NakajimaAbstract:Abstract The first total synthesis of Nephilatoxin-1 (NPTX-1), a Joro spider ( Nephila clavata ) toxin having a 4-hydroxyindole nucleus, has been achieved by using two key azide intermediates.
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Total Synthesis of Nephilatoxin-8 (NPTX-8), a New Neurotoxin of Joro Spider (Nephila clavata)
Chemistry Letters, 1993Co-Authors: Masaaki Miyashita, Terumi Nakajima, Masayuki Matsushita, Hideaki Sato, Takashi Toki, Hiroshi IrieAbstract:The first synthesis of Nephilatoxin-8 (NPTX-8), a new neurotoxin of Joro spider (Nephila clavata), has been achieved by employing two key azide intermediates for the incorporation of the characteristic polyamines of the toxin, cadaverine and spermidine.
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Synthetic studies on spider neurotoxins (I). Total synthesis of Nephilatoxins (NPTX-9 and NPTX-11), new neurotoxins of joro spider (Nephila clavata)
Tetrahedron Letters, 1992Co-Authors: Masaaki Miyashita, Hideaki Sato, Takashi Toki, Hiroshi Irie, Akira Yoshikoshi, Masayuki Matshushita, Tetsuji Yanami, Yasuo Kikuchi, Chikahisa Takasaki, Terumi NakajimaAbstract:Abstract The first and efficient synthesis of Nephilatoxins (NPTX-9 and NPTX-11), new neurotoxins of Joro spider ( Nephila clavata ), has been achieved by employing a key azide intermediate as the polyamine unit.
Fritz Vollrath - One of the best experts on this subject based on the ideXlab platform.
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spider silk fibre extrusion combined wide and small angle x ray microdiffraction experiments
International Journal of Biological Macromolecules, 2001Co-Authors: Christian Riekel, Fritz VollrathAbstract:Abstract The major and minor ampullate silks from live Nephila senegalensis (Tetragnathidae) and the major ampullate silk from Euprostenops spp. (Pisauridae) spiders were investigated in situ by X-ray diffraction during forced silking. Wide- (WAXS) and small-angle (SAXS) scattering patterns were obtained at the same time. WAXS data show that the thread at the exit of the spigots already contains β-sheet poly(alanine) crystallites. SAXS data suggest the presence of microfibrils with an axial repeating period of approximately 8 nm for both Nephila and Euprostenops . Minor ampullate (MI) Nephila silk, however, does not show this axial repeat which is probably due to a higher amount of crystal forming poly(alanine). A microfibrillar morphology, connected by a network of random polymer chains, can explain the presence of highly oriented crystallites, an oriented halo and a diffuse background in the WAXS patterns. At high reeling speeds, bound water is co-extruded with the fibre. It can be squeezed out of the fibre by friction at a needle. Under natural conditions it is the spider's tarsal claws which might serve to squeeze out the water to improve the mechanical properties of the thread during dragline production.
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Extreme body size variability in the golden silk spider ( Nephila edulis ) does not extend to genitalia
Journal of Zoology, 2000Co-Authors: Gabriele Uhl, Fritz VollrathAbstract:Nephila edulis is a spider with large body size variability in males and females. Genital characters show negative allometric values compared to somatic characters. In males, the embolus (the most important structure for sperm transfer) had a significantly lower coefficient of variation than body size. This suggests that male genitalia are under stabilizing selection favouring intermediate size. Female N. edulis showed a trend similar to males regarding allometric values in genitalia. In females, however, the variation coefficient in a specific genital character crucial for successful copulation did not differ from that of indicators for overall body size. This suggests that in Nephila the genitalia of the females experience less stabilizing selection than those of the males. In male and female genitalia, the mode of selection seems to cause developmental instability not in degrees of fluctuating asymmetry but in the degree of data scatter which indicates a lower coefficient of determination.
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Stress/Strain Characteristics and Biochemical Correlates of Spider Silks
1999Co-Authors: Fritz Vollrath, Yu-chu YangAbstract:Abstract : We examined the stress-strain characteristics of dragline silks from a range of spiders and found large inter and intraspecific differences. Moreover, we observed daily variability in silk from individuals of Nephila edulis and we can show that spider condition (starvation) affected silk properties, in particular that it tended to decrease breaking elongation. Reeling speed significantly affected silk properties in both Nephila edulis and Araneus diadematus, such that with increasing speed (1) breaking elongation decreased, (2) breaking stress increased and (3) Young's modulus increased. Analysis of our data from the different reeling speeds indicates that Nephila and Araneus dragline silks differ in basic properties.
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supercontracted spider dragline silk a solid state nmr study of the local structure
International Journal of Biological Macromolecules, 1999Co-Authors: J D Van Beek, Fritz Vollrath, J Kummerlen, Beat H MeierAbstract:The local structure of supercontracted dragline silk from the spider Nephila madagascariensis was investigated by solid-state nuclear magnetic resonance. Two-dimensional (2D) spin-diffusion experiments did not show any significant conformational changes in short-range order (and the secondary structure of the protein) upon supercontraction. Our results are in accordance with the proposal by Vollrath et al. (Proc R Soc London B 1996;263:147–151) that urea-supercontraction does not alter the local structure of spider dragline silk fundamentally. However, significant differences in the dynamics of the polypeptide chain upon supercontraction are detected at room temperature. At low temperature, these dynamics are frozen out. In addition, the role of the solvent (water) in the silk is investigated in Nephila edulis. Mobile water is detected at temperatures significantly below the freezing point of bulk water.
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Heterogeneous morphology of Nephila edulis spider silk and its significance for mechanical properties
Polymer, 1999Co-Authors: Zhengzhong Shao, Sebastian Frische, Fritz VollrathAbstract:Previous work has shown that dragline silk of Nephila madagascariensis is not homogeneous in cross-section. We report here that the core of Nephila edulis silk also contains extremely fine elongated, electron lucent domains. These domains may contribute to the exceptional tensile strength and toughness of this material by acting as stress concentration parts or (and) fluid-filled canaliculi.
I-min Tso - One of the best experts on this subject based on the ideXlab platform.
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SAXS images derived for MA silks of each species of spider.
2018Co-Authors: Sean J. Blamires, I-min Tso, Madeleine Nobbs, Penny J. Martens, Wei-tsung Chuang, Chung-kai Chang, Hwo-shuenn SheuAbstract:Where P = protein fed and N = protein deprived treatment, Ak = Argiope keyserlingi, Et = Eriophora transmarina, Lh = Latrodectus hasselti Np = Nephila plumipes, Pg = Phonognatha graeffei.
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Comparisons of the expressions of the MaSp1 genes previously isolated from the Argiope trifasciata (MaSp1a) and Latrodectus hesperus (MaSp1b), and the MaSp2 genes from Argiope trifasciata (MaSp2a) and Latrodectus hesperus (MaSp2b), across treatments
2018Co-Authors: Sean J. Blamires, I-min Tso, Madeleine Nobbs, Penny J. Martens, Wei-tsung Chuang, Chung-kai Chang, Hwo-shuenn SheuAbstract:Where P = protein fed and N = protein deprived treatments, Ak = Argiope keyserlingi, Et = Eriophora transmarina, Lh = Latrodectus hasselti Np = Nephila plumipes, Pg = Phonognatha graeffei.
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WAXS derived intensity vs 2θ plots for MA silks of each species.
2018Co-Authors: Sean J. Blamires, I-min Tso, Madeleine Nobbs, Penny J. Martens, Wei-tsung Chuang, Chung-kai Chang, Hwo-shuenn SheuAbstract:Where P = protein fed and N = protein deprived treatments, Ak = Argiope keyserlingi, Et = Eriophora transmarina, Lh = Latrodectus hasselti Np = Nephila plumipes, Pg = Phonognatha graeffei.
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SAXS derived intensity vs waveband parameter (q) plots for the MA silks each of the 5 species’ MA silk.
2018Co-Authors: Sean J. Blamires, I-min Tso, Madeleine Nobbs, Penny J. Martens, Wei-tsung Chuang, Chung-kai Chang, Hwo-shuenn SheuAbstract:Where P = protein fed and N = protein deprived treatments, Ak = Argiope keyserlingi, Et = Eriophora transmarina, Lh = Latrodectus hasselti Np = Nephila plumipes, Pg = Phonognatha graeffei.
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WAXS images derived for MA silks of each species of spider.
2018Co-Authors: Sean J. Blamires, I-min Tso, Madeleine Nobbs, Penny J. Martens, Wei-tsung Chuang, Chung-kai Chang, Hwo-shuenn SheuAbstract:Where P = protein fed and N = protein deprived treatments, Ak = Argiope keyserlingi, Et = Eriophora transmarina, Lh = Latrodectus hasselti Np = Nephila plumipes, Pg = Phonognatha graeffei.
Yung-hau Chang - One of the best experts on this subject based on the ideXlab platform.
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Biogeography and Speciation Patterns of the Golden Orb Spider Genus Nephila (Araneae: Nephilidae) in Asia
Zoological science, 2011Co-Authors: Yung-hau Chang, Matjaž Kuntner, Deborah Roan Smith, Ming-sheng Zhu, I-min TsoAbstract:The molecular phylogeny of the globally distributed golden orb spider genus Nephila (Nephilidae) was reconstructed to infer its speciation history, with a focus on SE Asian/W Pacific species. Five Asian, two Australian, four African, and one American species were included in the phylogenetic analyses. Other species in Nephilidae, Araneidae, and Tetragnathidae were included to assess their relationships with the genus Nephila, and one species from Uloboridae was used as the outgroup. Phylogenetic trees were reconstructed from one nuclear (18S) and two mitochondrial (COI and 16S) markers. Our molecular phylogeny shows that the widely distributed Asian/Australian species, N. pilipes, and an African species, N. constricta, form a clade that is sister to all other Nephila species. Nested in this Nephila clade are one clade with tropical and subtropical/temperate Asian/Australian species, and the other containing African and American species. The estimated divergence times suggest that diversification events within Nephila occurred during mid-Miocene to Pliocene (16 Mya-2 Mya), and these time periods were characterized by cyclic global warming/cooling events. According to Dispersal and Vicariance Analysis (DIVA), the ancestral range of the Asian/Australian clade was tropical Asia, and the ancestral range of the genus Nephila was either tropical Asia or Africa. We conclude that the speciation of the Asian/Australian Nephila species was driven by Neogene global cyclic climate changes. However, further population level studies comparing diversification patterns of sister species are needed to determine the mode of speciation of these species.
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original article phylogeography of the giant wood spider Nephila pilipes araneae from asian australian regions
Journal of Biogeography, 2006Co-Authors: Yung-hau Chang, Sinche Lee, I-min TsoAbstract:Aim There are currently few population genetic studies on widely distributed SE Asian terrestrial organisms. We have studied the genetic diversification pattern of the giant wood spider, Nephila pilipes (Araneae: Tetragnathidae) to see whether fluctuations in rain forest extents generated by Quaternary climatic changes left signatures on populations of this agile terrestrial arthropod.
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ORIGINAL ARTICLE: Phylogeography of the giant wood spider (Nephila pilipes, Araneae) from Asian–Australian regions
Journal of Biogeography, 2006Co-Authors: Yung-hau Chang, Sinche Lee, I-min TsoAbstract:Aim There are currently few population genetic studies on widely distributed SE Asian terrestrial organisms. We have studied the genetic diversification pattern of the giant wood spider, Nephila pilipes (Araneae: Tetragnathidae) to see whether fluctuations in rain forest extents generated by Quaternary climatic changes left signatures on populations of this agile terrestrial arthropod.