https://ogma.newcastle.edu.au/vital/access/ /manager/Index en-au 5 https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:14474 Sat 24 Mar 2018 08:18:51 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:44536 2 (PLA₂), and L-amino acid oxidase (LAAO) – in the venom of 39 species of Australian elapids (40% of terrestrial species diversity) and used linear parsimony and BayesTraits to investigate any correlation between enzyme activity and phylogeny or diet. Results: PLA₂ activity ranged from 0 to 481 nmol/min/mg of venom, and LAAO activity ranged from 0 to 351 nmol/min/mg. Phylogenetic comparative methods, implemented in BayesTraits showed that enzyme activity was strongly correlated with phylogeny, more so for LAAO activity. For example, LAAO activity was absent in both the Vermicella and Pseudonaja/Oxyuranus clade, supporting previously proposed relationships among these disparate taxa. There was no association between broad dietary categories and either enzyme activity. There was strong evidence for faster initial rates of change over evolutionary time for LAAO (delta parameter mean 0.2), but no such pattern in PLA₂ (delta parameter mean 0.64). There were some exceptions to the phylogenetic patterns of enzyme activity: different PLA₂ activity in the ecologically similar sister-species Denisonia devisi and D. maculata; large interspecific differences in PLA₂ activity in Hoplocephalus and Austrelaps. Conclusions: We have shown that phylogeny is a stronger influence on venom enzyme activity than diet for two of the four major enzyme families present in snake venoms. PLA₂ and LAAO activities had contrasting evolutionary dynamics with the higher delta value for PLA₂ Some species/individuals lacked activity in one protein family suggesting that the loss of single protein family may not incur a significant fitness cost.]]> Mon 17 Oct 2022 09:03:36 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:54722 Mon 11 Mar 2024 11:58:32 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:40389 Oxyuranus scutellatus from four localities on the north-east coast of Australia, spanning a distance of 2000 km. The intra-specific variation in taipan venom was considerably less than the inter-specific variation between it and the other Australian elapids to which it was compared. The electrophoretic venom profile of O. scutellatus was visually different to six other genera of Australian elapids, but not to its congener inland taipan O. microlepidotus. There was minimal geographical variation in taipan venom, as the intra-population variation exceeded the inter-population variation for enzymatic activity, procoagulant activity, and the abundance of neurotoxins. The pre-synaptic neurotoxin (taipoxin) was more abundant than the post-synaptic neurotoxins (3FTx), with a median of 11.0% (interquartile range (IQR): 9.7% to 18.3%; range: 6.7% to 23.6%) vs. a median of 3.4% (IQR: 0.4% to 6.7%; range: 0% to 8.1%). Three taipan individuals almost completely lacked post-synaptic neurotoxins, which was not associated with geography and occurred within two populations. We found no evidence of sexual dimorphism in taipan venom. Our study provides a basis for evaluating the significance of intra-specific venom variation within a phylogenetic context by comparing it to the inter-specific and inter-generic variation. The considerable intra-population variation we observed supports the use of several unpooled individuals from each population when making inter-specific comparisons.]]> Mon 11 Jul 2022 11:21:41 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:51420 Mon 04 Sep 2023 14:58:04 AEST ]]>