title: Ontogenetic changes in Phoneutria nigriventer (Araneae, Ctenidae) spider venom.
abstract: Venom-yield and composition of differently sized individuals of the medically most important Brazilian spider Phoneutria nigriventer (Keyserling, 1891) was analysed. During growth the venom-mass increases according to a fourth order function of the prosoma size, which mainly reflects an increase of the venom gland volume. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed increasing percentages of proteins < or = 17 kDa from 4.1% in the smallest analysed spiders (2-3 months-old) to 79.1% in adult female venom. Additionally, high-pressure liquid-chromatography showed an increase of a single ('main') peak from 4.6 to 64.9%, while the overall number of other major-peaks decreased. Venom from young instars completely lacked lethality in mice up to a dose of 3.28 mg/kg i.v. as compared to a LD(50) of 0.63 mg/kg for adult female or 1.57 mg/kg for adult male venom that we reported previously. In conclusion, ontogenetic changes in venom protein-composition of growing P. nigriventer are suggested to produce increasing lethality in vertebrates.
authors.affiliation: Department of Neuropharmacology, Zoological Institute, Faculty of Biology, University of Tübingen, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Herzig
authors.forename: Richard John
authors.initials: RJ
authors.lastname: Ward
authors.forename: Wagner Ferreira
authors.initials: WF
authors.lastname: Dos Santos
mesh_terms: D000367:Age Factors; D000818:Animals; D001938:Brazil; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D007928:Lethal Dose 50; D051379:Mice; D011506:Proteins / Q000737:chemistry*; D013111:Spider Venoms / Q000737:chemistry* / Q000633:toxicity*; D013112:Spiders / Q000254:growth & development* / Q000378:metabolism
chemical_list: D011506:Proteins; D013111:Spider Venoms