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1
Mcalees, Trudi J., and Linda A. Abraham. "Australian elapid snake envenomation in cats: Clinical priorities and approach." Journal of Feline Medicine and Surgery 19, no. 11 (October 25, 2017): 1131–47. http://dx.doi.org/10.1177/1098612x17735761.
Повний текст джерелаАнотація:
Practical relevance: No fewer than 140 species of terrestrial snakes reside in Australia, 92 of which possess venom glands. With the exception of the brown tree snake, the venom-producing snakes belong to the family Elapidae. The venom of a number of elapid species is more toxic than that of the Indian cobra and eastern diamondback rattle snake, which has earned Australia its reputation for being home to the world’s most venomous snakes. Clinical challenges: The diagnosis of elapid snake envenomation is not always easy. Identification of Australian snakes is not straightforward and there are no pathognomonic clinical signs. In cats, diagnosis of envenomation is confounded by the fact that, in most cases, there is a delay in seeking veterinary attention, probably because snake encounters are not usually witnessed by owners, and also because of the tendency of cats to hide and seek seclusion when unwell. Although the administration of antivenom is associated with improved outcomes, the snake venom detection kit and antivenom are expensive and so their use may be precluded if there are financial constraints. Evidence base: In providing comprehensive guidance on the diagnosis and treatment of Australian elapid snake envenomation in cats, the authors of this review draw on the published veterinary, medical and toxicology literature, as well as their professional experience as specialists in medicine, and emergency medicine and critical care.
2
Takasaki, C., and N. Tamiya. "Isolation and amino acid sequence of a short-chain neurotoxin from an Australian elapid snake, Pseudechis australis." Biochemical Journal 232, no. 2 (December 1, 1985): 367–71. http://dx.doi.org/10.1042/bj2320367.
Повний текст джерелаАнотація:
A short-chain neurotoxin Pseudechis australis a (toxin Pa a) was isolated from the venom of an Australian elapid snake Pseudechis australis (king brown snake) by sequential chromatography on CM-cellulose, Sephadex G-50 and CM-cellulose columns. Toxin Pa a has an LD50 (intravenous) value of 76 micrograms/kg body wt. in mice and consists of 62 amino acid residues. The amino acid sequence of Pa a shows considerable homology with those of short-chain neurotoxins of elapid snakes, especially of true sea snakes.
3
Tasoulis, Theo, C. Ruth Wang, Joanna Sumner, Nathan Dunstan, Tara L. Pukala, and Geoffrey K. Isbister. "The Unusual Metalloprotease-Rich Venom Proteome of the Australian Elapid Snake Hoplocephalus stephensii." Toxins 14, no. 5 (April 28, 2022): 314. http://dx.doi.org/10.3390/toxins14050314.
Повний текст джерелаАнотація:
The Australasian region is home to the most diverse elapid snake radiation on the planet (Hydrophiinae). Many of these snakes have evolved into unique ecomorphs compared to elapids on other continents; however, their venom compositions are poorly known. The Australian elapid Hoplocephalus stephensii (Stephen’s banded snake) is an arboreal snake with a unique morphology. Human envenoming results in venom-induced consumption coagulopathy, without neurotoxicity. Using transcriptomics and a multi-step fractionation method involving reverse-phase high-performance liquid chromatography, sodium dodecyl sulfate polyacrylamide gel electrophoresis and bottom-up proteomics, we characterized the venom proteome of H. stephensii. 92% of the total protein component of the venom by weight was characterized, and included all dominant protein families and 4 secondary protein families. Eighteen toxins made up 76% of the venom, four previously characterized and 14 new toxins. The four dominant protein families made up 77% of the venom, including snake venom metalloprotease (SVMP; 36.7%; three identified toxins), phospholipase A2 (PLA2; 24.0%; five identified toxins), three-finger toxin (3FTx; 10.2%; two toxins) and snake venom serine protease (SVSP; 5.9%; one toxin; Hopsarin). Secondary protein families included L-amino acid oxidase (LAAO; 10.8%; one toxin), natriuretic peptide (NP; 0.8%; two toxins), cysteine-rich secretory protein (CRiSP; 1.7%; two toxins), c-type lectin (CTL; 1.1%; one toxin), and one minor protein family, nerve growth factor (NGF; 0.8%; one toxin). The venom composition of H. stephensii differs to other elapids, with a large proportion of SVMP and LAAO, and a relatively small amount of 3FTx. H. stephensii venom appeared to have less toxin diversity than other elapids, with only 18 toxins making up three-quarters of the venom.
4
HAINS, Peter G., and Kevin W. BROADY. "Purification and inhibitory profile of phospholipase A2 inhibitors from Australian elapid sera." Biochemical Journal 346, no. 1 (February 8, 2000): 139–46. http://dx.doi.org/10.1042/bj3460139.
Повний текст джерелаАнотація:
Although the resistance of snakes to their own venom is well known, until now no investigators have examined the serum of Australian snakes. Here we describe the identification and purification of a range of phospholipase A2 (PLA2) inhibitors from the serum of Australian elapids. All PLA2 inhibitors were composed of two protein chains, an α-chain and a β-chain. The α-chains were approx. 22.5 kDa in size and variably glycosylated, whereas the β-chains were approx. 19.8 kDa in size and not glycosylated. Identification of isoforms of the two subunit chains was significant because three of the six sera examined were from single snake specimens. In addition, the glycosylation patterns of the α-chains were thoroughly investigated in these unpooled sera. The functional and structural properties of the purified inhibitors were studied. Uniquely, a snake PLA2 inhibitor was found to inhibit human type II PLA2 enzyme, which has implications for the treatment of the many diseases in which PLA2 enzymes have been implicated. Further, we demonstrate that the inhibitor forms a non-covalent association with a purified PLA2 enzyme. Finally, the purified PLA2 inhibitor was shown to protect in vivo against the lethal affects of a homologous PLA2 enzyme, suggesting a role for PLA2 inhibitors in the treatment of snake bite victims.
5
Llewelyn, John, Richard Shine, and Jonathan K. Webb. "Thermal regimes and diel activity patterns of four species of small elapid snakes from south-eastern Australia." Australian Journal of Zoology 53, no. 1 (2005): 1. http://dx.doi.org/10.1071/zo04037.
Повний текст джерелаАнотація:
Two of the most basic biological attributes for any ectothermic animal are the times of day that it is active and the body temperatures that it exhibits. Published studies on reptile biology display a heavy bias towards diurnal lizards from Northern Hemisphere habitats. To help redress this imbalance, we quantified thermal regimes and activity times in four species of small Australian elapid snakes. Mean selected body temperature in a thermal gradient was affected by the time of testing (i.e. night v. day), with snakes choosing higher body temperatures at night than by day. In outdoor enclosures, whip snakes (Demansia psammophis) were shuttling heliotherms active only during daylight hours at relatively high body temperatures; in a laboratory thermal gradient these animals selected high body temperatures (mean 31.3°C during the day and 33.2°C at night). The other three taxa – golden-crowned snakes (Cacophis squamulosus), small-eyed snakes (Cryptophis nigrescens) and marsh snakes (Hemiaspis signata) – were active mostly at night at relatively low body temperatures, and selected low body temperatures in a thermal gradient (18.1–23.4°C). Thus, mean selected body temperatures differ substantially among sympatric elapid species in south-eastern Australia and are correlated with times of activity.
6
Isbister, Geoffrey K., Nandita Mirajkar, Kellie Fakes, Simon G. A. Brown, and Punnam Chander Veerati. "Phospholipase A2 (PLA2) as an Early Indicator of Envenomation in Australian Elapid Snakebites (ASP-27)." Biomedicines 8, no. 11 (October 29, 2020): 459. http://dx.doi.org/10.3390/biomedicines8110459.
Повний текст джерелаАнотація:
Early diagnosis of snake envenomation is essential, especially neurotoxicity and myotoxicity. We investigated the diagnostic value of serum phospholipase (PLA2) in Australian snakebites. In total, 115 envenomated and 80 non-envenomated patients were recruited over 2 years, in which an early blood sample was available pre-antivenom. Serum samples were analyzed for secretory PLA2 activity using a Cayman sPLA2 assay kit (#765001 Cayman Chemical Company, Ann Arbor MI, USA). Venom concentrations were measured for snake identification using venom-specific enzyme immunoassay. The most common snakes were Pseudonaja spp. (33), Notechis scutatus (24), Pseudechis porphyriacus (19) and Tropidechis carinatus (17). There was a significant difference in median PLA2 activity between non-envenomated (9 nmol/min/mL; IQR: 7–11) and envenomated patients (19 nmol/min/mL; IQR: 10–66, p < 0.0001) but Pseudonaja spp. were not different to non-envenomated. There was a significant correlation between venom concentrations and PLA2 activity (r = 0.71; p < 0.0001). PLA2 activity was predictive for envenomation; area under the receiver-operating-characteristic curve (AUC-ROC), 0.79 (95% confidence intervals [95%CI]: 0.72–0.85), which improved with brown snakes excluded, AUC-ROC, 0.88 (95%CI: 0.82–0.94). A cut-point of 16 nmol/min/mL gives a sensitivity of 72% and specificity of 100% for Australian snakes, excluding Pseudonaja. PLA2 activity was a good early predictor of envenomation in most Australian elapid bites. A bedside PLA2 activity test has potential utility for early case identification but may not be useful for excluding envenomation.
7
Shelton, Michael B., and Ross L. Goldingay. "Comparative survey techniques for a cryptic Australian snake (Hoplocephalus bitorquatus)." Australian Journal of Zoology 68, no. 2 (2020): 68. http://dx.doi.org/10.1071/zo20062.
Повний текст джерелаАнотація:
Ecologists endeavour to develop survey techniques that are cost-effective for the species they target and robust enough for statistical analysis. Using time as a measure of effort, we compared visual encounter surveys with artificial cover objects (strapped to trees), targeting an arboreal elapid, the pale-headed snake (Hoplocephalus bitorquatus) and its potential prey (geckos). Within a red gum forest vegetation community with relatively high snake density, capture rates were 0.6 ± 0.1 (s.e.) snakes/person-hour using visual encounter surveys, compared with only 0.1 ± 0.1 snakes/person-hour using cover objects. The probability of detection of pale-headed snakes was estimated from occupancy modelling at 0.70 ± 0.06 in visual encounter surveys and 0.19 ± 0.09 in cover object surveys. Gecko capture rates (among all vegetation communities) were significantly greater (P < 0.001) using cover objects. The probability of detection of geckos was estimated from occupancy modelling at 0.77 ± 0.05 in visual encounter surveys and 0.97 ± 0.02 in cover object surveys. Geckos favoured (P < 0.001) cover objects facing south during all seasons except winter. Artificial cover objects may provide some value in detecting pale-headed snakes in vegetation communities where habitat resources are limited; however, where resources are plentiful, visual encounter surveys are likely to remain the most cost-effective survey option.
8
White, Julian. "The generic classification of the Australian terrestrial elapid snakes." Toxicon 30, no. 8 (August 1992): 942. http://dx.doi.org/10.1016/0041-0101(92)90416-3.
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9
Whitaker, P. B., and R. Shine. "When, where and why do people encounter Australian brownsnakes (Pseudonaja textilis : Elapidae)?" Wildlife Research 26, no. 5 (1999): 675. http://dx.doi.org/10.1071/wr98043.
Повний текст джерелаАнотація:
Encounters between humans and dangerously venomous snakes put both participants at serious risk, so the determinants of such encounters warrant attention. Pseudonaja textilis is a large fast-moving elapid snake responsible for most snakebite fatalities in Australia. As part of a broad ecological study of this species in agricultural land near Leeton, New South Wales, we set out to identify factors influencing the probability that a human walking in farmland would come into close proximity to a brownsnake. Over a three-year period, we walked regular transects to quantify the number and rate of snake encounters, and the proportion of snakes above ground that could be seen. The rate of encounters depended upon a series of factors, including season, time of day, habitat type, weather conditions (wind and air temperature) and shade (light v. dark) of the observers’ clothing. Interactions between factors were also important: for example, the effect of air temperature on encounter probability differed with season and snake gender, and the effect of the observers’ shade of clothing differed with cloud cover. Remarkably, even a highly-experienced observer actually saw <25% of the telemetrically monitored snakes that were known to be active (i.e. above ground) nearby. This result reflects the snakes’ ability to evade people and to escape detection, even in the flat and sparsely vegetated study area. The proportion of snakes that were visible was influenced by the same kinds of factors as described above. Most of the factors biasing encounter rates are readily interpretable from information on other facets of the species’ ecology, and knowledge of these factors may facilitate safer coexistence between snakes and people.
10
Pycroft, Kyle, Bryan G. Fry, Geoffrey K. Isbister, Sanjaya Kuruppu, Josie Lawrence, A. Ian Smith, and Wayne C. Hodgson. "Toxinology of Venoms from Five Australian Lesser Known Elapid Snakes." Basic & Clinical Pharmacology & Toxicology 111, no. 4 (July 4, 2012): 268–74. http://dx.doi.org/10.1111/j.1742-7843.2012.00907.x.
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11
KEOGH, J. SCOTT. "Evolutionary implications of hemipenial morphology in the terrestrial Australian elapid snakes." Zoological Journal of the Linnean Society 125, no. 2 (February 1999): 239–78. http://dx.doi.org/10.1111/j.1096-3642.1999.tb00592.x.
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12
Fearn, S., J. Dowde, and D. F. Trembath. "Body size and trophic divergence of two large sympatric elapid snakes (Notechis scutatus and Austrelaps superbus) (Serpentes:Elapidae) in Tasmania." Australian Journal of Zoology 60, no. 3 (2012): 159. http://dx.doi.org/10.1071/zo12004.
Повний текст джерелаАнотація:
Tiger snakes (Notechis scutatus) and lowland copperheads (Austrelaps superbus) are both large viviparous elapid snakes confined to the cooler, mesic regions of southern Australia. In spite of both species being common and widespread in the island state of Tasmania, no quantified studies on the trophic ecology of these two snakes from the main island has been published. During a two-year period we collected field data from 127 adult A. superbus and 74 adult N. scutatus from throughout eastern Tasmania. For both species, males were larger than females with respect to all measured parameters, including mass and head size. Reproduction in females was strongly seasonal and clutch size was not related to maternal body size. N. scutatus has a larger head than A. superbus and consequently ingests both small and large prey. N. scutatus in our study displayed the most catholic diet of any Australian elapid studied to date and consumed mammals (possum, bandicoot, antechinus, rats, mice), birds (fairy wrens), fish (eel, trout) and frogs. A. superbus shows a more specialist diet of large volumes of predominately ectothermic prey (frogs, lizards, snakes) even at maximal sizes and was more likely to contain ingested prey than specimens of N. scutatus. Distinctive rodent bite scars were common on N. scutatus but rare on A. superbus. The high frequency of rodent bite scars on N. scutatus further supports our findings of a primarily endothermic diet for mature specimens. We suggest that significant differences in head size, and hence diet, as well as a taxonomically diverse suite of potential prey in Tasmania allow both these large snakes to coexist in sympatry and avoid interspecific competitive exclusion.
13
Youngman, Nicholas J., Joshua Llinas, and Bryan G. Fry. "Evidence for Resistance to Coagulotoxic Effects of Australian Elapid Snake Venoms by Sympatric Prey (Blue Tongue Skinks) but Not by Predators (Monitor Lizards)." Toxins 13, no. 9 (August 24, 2021): 590. http://dx.doi.org/10.3390/toxins13090590.
Повний текст джерелаАнотація:
Some Australian elapids possess potently procoagulant coagulotoxic venoms which activate the zymogen prothrombin into the functional enzyme thrombin. Although the activity of Australian elapid prothrombin-activators has been heavily investigated with respect to the mammalian, and in particular, human clotting cascades, very few studies have investigated the activity of their venom upon reptile plasmas. This is despite lizards representing both the primary diet of most Australian elapids and also representing natural predators. This study investigated the procoagulant actions of a diverse range of Australian elapid species upon plasma from known prey species within the genera Tiliqua (blue tongue skinks) as well as known predator species within the genera Varanus (monitor lizards). In addition to identifying significant variation in the natural responses of the coagulation cascade between species from the genera Tiliqua and Varanus relative to each other, as well as other vertebrate lineages, notable differences in venom activity were also observed. Within the genus Tiliqua, both T. rugosa and T. scincoides plasma displayed significant resistance to the procoagulant activity of Pseudechis porphyriacus venom, despite being susceptible to all other procoagulant elapid venoms. These results indicate that T. rugosa and T. scincoides have evolved resistance within their plasma to the coagulotoxic venom activity of the sympatric species P. porphyriacus. Other venoms were able to activate Tiliqua prothrombin, which suggests that the lessened activity of P. porphyriacus venom is not due to modifications of the prothrombin and may instead be due to a serum factor that specifically binds to P. porphyriacus toxins, as has been previously seen for squirrels resistant to rattlesnake venom. In contrast, none of the predatory lizards studied (Varanus giganteus, V. mertensi and V. varius) demonstrated resistance to the venom. This suggests that the mechanical protection afforded by thick osteodermic scales, and prey handling behaviour, removes a selection pressure for the evolution of resistance in these large predatory lizards. These results therefore reveal differential interactions between venoms of snakes with sympatric lizards that are on opposite sides of the predator–prey arms race.
14
Johnston, Gregory R. "Seasonal Changes in Dorsal Reflectance of Two Species of Australian Elapid Snakes." Journal of Herpetology 28, no. 1 (March 1994): 109. http://dx.doi.org/10.2307/1564690.
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Rohr, Detlef H. "Reproductive trade-offs in the elapid snakes Austrelaps superbus and Austrelaps ramsayi." Canadian Journal of Zoology 79, no. 6 (June 1, 2001): 1030–37. http://dx.doi.org/10.1139/z01-074.
Повний текст джерелаАнотація:
Reproductive traits and the trade-offs among these traits were examined in two venomous terrestrial elapid snakes, the Australian lowland copperhead, Austrelaps superbus, and the Australian highland copperhead, Austrelaps ramsayi. Sampling was difficult, so gravid females had to be held in captivity for up to several months prior to parturition. Analyses showed that captivity affected the time of parturition and maternal body condition, but it had no apparent effect on offspring traits. The results were corroborated by conducting partial follicular ablations in gravid A. superbus with fully yolked follicles. While these females gave birth earlier than unmanipulated females, offspring size was highly correlated with follicular size at the time of ablation and fell within the size range observed in the other females. This suggests that offspring size is fixed by the time follicles are fully yolked. Among unmanipulated females, reproductive traits were similar in A. superbus and A. ramsayi, but relationships among the traits differed. In the A. superbus sample, the trade-off between litter size and offspring size only became apparent after partial correlations, presumably because spring foraging obscured this relationship. In the A. ramsayi sample, however, the trade-off between litter size and offspring size was very pronounced. At this locality, there was no evidence of spring foraging, and snakes had fully developed follicles before or soon after they emerged from hibernation. This reduces the temporal separation between the times when litter size and offspring size are fixed and may allow greater control over the distribution of resources to offspring as a function of litter size.
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Llewelyn, John, Jonathan K. Webb, and Richard Shine. "Flexible Defense: Context-Dependent Antipredator Responses of Two Species of Australian Elapid Snakes." Herpetologica 66, no. 1 (March 2010): 1–11. http://dx.doi.org/10.1655/07-082.1.
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17
SCANLON, J. D., and R. SHINE. "Dentition and diet in snakes: adaptations to oophagy in the Australian elapid genusSimoselaps." Journal of Zoology 216, no. 3 (November 1988): 519–28. http://dx.doi.org/10.1111/j.1469-7998.1988.tb02448.x.
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Weinstein, Scott A., Peter J. Mirtschin, and Julian White. "Risks and realities of single vial antivenom recommendations for envenoming by Australian elapid snakes." Medical Journal of Australia 211, no. 11 (August 22, 2019): 492. http://dx.doi.org/10.5694/mja2.50314.
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Weinstein, Scott A., Peter J. Mirtschin, and Julian White. "Risks and realities of single vial antivenom recommendations for envenoming by Australian elapid snakes." Medical Journal of Australia 213, no. 1 (June 11, 2020): 46. http://dx.doi.org/10.5694/mja2.50651.
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Isbister, Geoffrey K., and Nicholas A. Buckley. "Risks and realities of single vial antivenom recommendations for envenoming by Australian elapid snakes." Medical Journal of Australia 213, no. 1 (June 11, 2020): 45. http://dx.doi.org/10.5694/mja2.50652.
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CARMEL, BP, and V. GROVES. "Chronic cryptosporidiosis in Australian elapid snakes: control of an outbreak in a captive colony." Australian Veterinary Journal 70, no. 8 (August 1993): 293–95. http://dx.doi.org/10.1111/j.1751-0813.1993.tb07977.x.
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22
Reed, Robert N., and Richard Shine. "Lying in Wait for Extinction: Ecological Correlates of Conservation Status among Australian Elapid Snakes." Conservation Biology 16, no. 2 (April 2002): 451–61. http://dx.doi.org/10.1046/j.1523-1739.2002.02283.x.
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G. Thompson, Graham, Scott A. Thompson, Philip C. Withers, and Eric R. Pianka. "Diversity and abundance of pit-trapped reptiles in Australian arid and mesic habitats: Biodiversity for Environmental Impact Assessments." Pacific Conservation Biology 9, no. 2 (2003): 120. http://dx.doi.org/10.1071/pc030120.
Повний текст джерелаАнотація:
Based on pit-trapping data for reptile assemblages from mesic, semi-arid and arid Australian sites, we examined species richness, diversity and evenness for general patterns. Reptile assemblages in Australian arid and semi-arid areas are generally species rich, have a high diversity, and have a high proportion of species that are rarely caught. Skinks are generally the most abundant taxa, followed by geckos and agamids. Varanids, elapid and blind snakes are less frequently caught, and pygopods are seldom caught in pit-trapping programmes. However, there was considerable variability in the pattern of reptile assemblages across the Australian arid and semi-arid landscape, and even among closely located sites within the same soil and vegetation zones. A high proportion of arid and semi-arid reptile species are rarely caught in pit-traps. Western Australian Environmental Protection Authority's current requirements for assessing the effects of a potential disturbance, which are based on desktop study and small-scale field survey, are inadequate to describe biodiversity at the genetic, species and ecosystem levels, and also in terms of ecosystem function. If the Environmental Protection Authority considers rare species are an important component of the biodiversity of an area, then a greater level of trapping is required for the preparation of an environmental impact assessment than is generally occurring at present.
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Cabrelli, Abigail L., Adam J. Stow, and Lesley Hughes. "A framework for assessing the vulnerability of species to climate change: a case study of the Australian elapid snakes." Biodiversity and Conservation 23, no. 12 (August 1, 2014): 3019–34. http://dx.doi.org/10.1007/s10531-014-0760-0.
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MARYAN, BRAD, IAN G. BRENNAN, MARK N. HUTCHINSON, and LUKAS S. GEIDANS. "What’s under the hood? Phylogeny and taxonomy of the snake genera Parasuta Worrell and Suta Worrell (Squamata: Elapidae), with a description of a new species from the Pilbara, Western Australia." Zootaxa 4778, no. 1 (May 13, 2020): 1–47. http://dx.doi.org/10.11646/zootaxa.4778.1.1.
Повний текст джерелаАнотація:
Despite decades of phylogenetic studies, the generic and species-level relationships of some Australian elapid snakes remain problematic. The morphologically conservative genus Parasuta comprises small nocturnal snakes with a particularly obfuscated taxonomic history. Here we provide a molecular phylogenetic analysis of all currently recognised species including members of the sister genus Suta and provide new morphological data that lead to a taxonomic revision of generic and species boundaries. We failed to find support for monophyly of Parasuta or Suta, instead supporting previous evidence that these two genera should be combined. Our species-level investigations revise the boundaries between P. gouldii (Gray) and P. spectabilis (Krefft) resulting in recognition that both P. spectabilis bushi (Storr) and P. spectabilis nullarbor (Storr) are conspecific with P. gouldii. We also find the Pilbara population of P. monachus (Storr) to be specifically distinct. As a consequence of this information, we synonymise Parasuta with its senior synonym Suta, redescribe S. gouldii, S. monachus and S. spectabilis to clarify morphological and geographical boundaries and describe S. gaikhorstorum sp. nov., which differs from all other described Suta species, including the geographically proximate and similar-looking S. monachus, by a combination of molecular genetic markers, morphometric attributes, details of colouration and scalation. The recognition of S. gaikhorstorum sp. nov. adds to the growing list of the many endemic reptiles from this exceptionally diverse biotic region. We also designate a lectotype for S. spectabilis from the original syntype series, highlight a distinctive population from the Great Victoria Desert in Western Australia and comment on further unresolved issues regarding the relationships between S. dwyeri (Worrell) and S. nigriceps (Gȕnther).
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Skejic, Jure, David L. Steer, Nathan Dunstan, and Wayne C. Hodgson. "Label-Free (XIC) Quantification of Venom Procoagulant and Neurotoxin Expression in Related Australian Elapid Snakes Gives Insight into Venom Toxicity Evolution." Journal of Proteome Research 14, no. 11 (October 21, 2015): 4896–906. http://dx.doi.org/10.1021/acs.jproteome.5b00764.
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Noutsos, Tina, Bart J. Currie, Rachel A. Lek, and Geoffrey K. Isbister. "Snakebite associated thrombotic microangiopathy: a systematic review of clinical features, outcomes, and evidence for interventions including plasmapheresis." PLOS Neglected Tropical Diseases 14, no. 12 (December 8, 2020): e0008936. http://dx.doi.org/10.1371/journal.pntd.0008936.
Повний текст джерелаАнотація:
Snakebite is a neglected tropical disease with significant morbidity and mortality. Thrombotic microangiopathy (TMA) is an important but poorly understood complication of snakebite associated with acute kidney injury (AKI). Numerous treatments have been attempted based on limited evidence. We conducted a systematic review of TMA following snakebite using a pre-determined case definition of blood film red cell schistocytes or histologically diagnosed TMA. The search strategy included major electronic databases and grey literature. We present a descriptive synthesis for the outcomes of AKI, dialysis free survival (DFS), other end-organ damage, overall survival, and interventions with antivenom and therapeutic plasmapheresis (TPE). This study was prospectively registered with PROSPERO (CRD42019121436). Seventy-two studies reporting 351 cases were included, predominantly small observational studies. Heterogeneity for study selection, design, reporting and outcomes were observed. The commonest envenoming species were hump-nosed vipers (Hypnale spp.), Russell’s viper (Daboia russelii) and Australian brown snakes (Pseudechis spp.). The prevalence of TMA was at least 5.4% in proven and probable Hypnale bites, and 10–15% of Australian elapid envenomings, AKI occurred in 94% (293/312) of TMA cases, excluding case reports. The majority of cases with AKI required dialysis. Included prospective and retrospective cohort studies reporting interventions and renal outcomes showed no evidence for benefit from antivenom or TPE with respect to DFS in dialysis dependant AKI. The Grading of Recommendations, Assessment, Development and Evaluations (GRADE) assessment for quality of accumulated evidence for interventions was low. The major complication of TMA following snakebite is AKI. AKI improves in most cases. We found no evidence to support benefit from antivenom in snakebite associated TMA, but antivenom remains the standard of care for snake envenoming. There was no evidence for benefit of TPE in snakebite associated TMA, so TPE cannot be recommended. The quality of accumulated evidence was low, highlighting a need for high quality larger studies.
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Grundler, Michael C., and Daniel L. Rabosky. "Trophic divergence despite morphological convergence in a continental radiation of snakes." Proceedings of the Royal Society B: Biological Sciences 281, no. 1787 (July 22, 2014): 20140413. http://dx.doi.org/10.1098/rspb.2014.0413.
Повний текст джерелаАнотація:
Ecological and phenotypic convergence is a potential outcome of adaptive radiation in response to ecological opportunity. However, a number of factors may limit convergence during evolutionary radiations, including interregional differences in biogeographic history and clade-specific constraints on form and function. Here, we demonstrate that a single clade of terrestrial snakes from Australia—the oxyuranine elapids—exhibits widespread morphological convergence with a phylogenetically diverse and distantly related assemblage of snakes from North America. Australian elapids have evolved nearly the full spectrum of phenotypic modalities that occurs among North American snakes. Much of the convergence appears to involve the recurrent evolution of stereotyped morphologies associated with foraging mode, locomotion and habitat use. By contrast, analysis of snake diets indicates striking divergence in feeding ecology between these faunas, partially reflecting regional differences in ecological allometry between Australia and North America. Widespread phenotypic convergence with the North American snake fauna coupled with divergence in feeding ecology are clear examples of how independent continental radiations may converge along some ecological axes yet differ profoundly along others.
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Keogh, J. Scott, Ian A. W. Scott, and John D. Scanlon. "Molecular phylogeny of viviparous Australian elapid snakes: affinities of Echiopsis atriceps (Storr, 1980) and Drysdalia coronata (Schlegel, 1837), with description of a new genus." Journal of Zoology 252, no. 3 (November 2000): 317–26. http://dx.doi.org/10.1111/j.1469-7998.2000.tb00626.x.
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Price-Rees, Samantha J., Gregory P. Brown, and Richard Shine. "Predation on toxic cane toads (Bufo marinus) may imperil bluetongue lizards (Tiliqua scincoides intermedia, Scincidae) in tropical Australia." Wildlife Research 37, no. 2 (2010): 166. http://dx.doi.org/10.1071/wr09170.
Повний текст джерелаАнотація:
Context. Detecting ecological impacts of invasive species can be extremely difficult. Even major population declines may be undetectable without extensive long-term data if the affected taxon is rare and/or difficult to census, and exhibits stochastic variation in abundance as a result of other factors. Our data suggest such a situation in an iconic Australian reptile species, the bluetongue lizard. Originally restricted to Central and South America, cane toads (Bufo marinus) are rapidly spreading through tropical Australia. Most native predators have no evolutionary history of exposure to the toads’ distinctive chemical defences (bufadienolides), and many varanid lizards, elapid snakes, crocodiles and marsupials have been killed when they have attempted to consume toads. Aims. Scincid lizards have not been considered vulnerable to toad invasion; however, one lineage (the bluetongues, genus Tiliqua) consists of large omnivores that may be affected. Our field and laboratory research aimed to elucidate this concern. Methods. Nightly surveys for bluetongue lizards (Tiliqua scincoides intermedia) and cane toads were conducted along two adjacent roadways on the Adelaide River floodplain of the Northern Territory. Scent discrimination trials in the laboratory assessed lizard responses to chemical cues from three food types (native frogs, cane toads and ‘preferred foods’) by counting tongue-flicks and biting elicited by cotton swabs. A subset of lizards was presented with live toads. Key results. Numbers of bluetongues encountered during standardised field surveys in the Darwin region declined soon after toads arrived, and we have not recorded a single lizard for the last 20 months. In the laboratory, foraging responses of bluetongues were as intense to cane-toad scent as to the scent of native frogs, and many of the lizards we tested attempted to consume toads, and were poisoned as a result. Conclusions and implications. The population decline of bluetongues in this region appears to have been the direct result of fatal ingestion of toxic cane toads. Our studies thus add a scincid lizard species to the list of native Australian predators imperilled by cane-toad invasion, and point to the difficulty of detecting invader impact even for an iconic species in a system subject to detailed survey work.
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Webb, Jonathan K., Weiguo Du, David Pike, and Richard Shine. "Generalization of predator recognition: Velvet geckos display anti-predator behaviours in response to chemicals from non-dangerous elapid snakes." Current Zoology 56, no. 3 (June 1, 2010): 337–42. http://dx.doi.org/10.1093/czoolo/56.3.337.
Повний текст джерелаАнотація:
Abstract Many prey species detect chemical cues from predators and modify their behaviours in ways that reduce their risk of predation. Theory predicts that prey should modify their anti-predator responses according to the degree of threat posed by the predator. That is, prey should show the strongest responses to chemicals of highly dangerous prey, but should ignore or respond weakly to chemicals from non-dangerous predators. However, if anti-predator behaviours are not costly, and predators are rarely encountered, prey may exhibit generalised antipredator behaviours to dangerous and non-dangerous predators. In Australia, most elapid snakes eat lizards, and are therefore potentially dangerous to lizard prey. Recently, we found that the nocturnal velvet gecko Oedura lesueurii responds to chemicals from dangerous and non-dangerous elapid snakes, suggesting that it displays generalised anti-predator behaviours to chemicals from elapid snakes. To explore the generality of this result, we videotaped the behaviour of velvet geckos in the presence of chemical cues from two small elapid snakes that rarely consume geckos: the nocturnal golden-crowned snake Cacophis squamulosus and the diurnal marsh snake Hemiaspis signata. We also videotaped geckos in trials involving unscented cards (controls) and cologne-scented cards (pungency controls). In trials involving Cacophis and Hemiaspis chemicals, 50% and 63% of geckos spent long time periods (> 3 min) freezing whilst pressed flat against the substrate, respectively. Over half the geckos tested exhibited anti-predator behaviours (tail waving, tail vibration, running) in response to Cacophis (67%) or Hemiaspis (63%) chemicals. These behaviours were not observed in control or pungency control trials. Our results support the idea that the velvet gecko displays generalised anti-predator responses to chemical cues from elapid snakes. Generalised responses to predator chemicals may be common in prey species that co-occur with multiple, ecologically similar, dangerous predators.
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Mengden, G. A., and M. Fitzgerald. "Captive Breeding and Oviparity in Pseudechis butleri (Serpentes: Elapidae)." Amphibia-Reptilia 8, no. 2 (1987): 165–69. http://dx.doi.org/10.1163/156853887x00423.
Повний текст джерелаАнотація:
AbstractThe recently described Australian elapid snake Pseudechis butleri is the least well known representative of the genus in terms of basic biology and reproductive mode. This report describes the reproductive behavior, oviparity and female defence of the egg clutch. Ontogenetic colour change and sexual size dimorphism from birth are demonstrated in the offspring. A review of the literature suggests that these conditions are relatively rare amongst elapids.
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Khalid, Huda, Maowia Mohammed Mukhtar, and Nicki Konstantakopoulos. "Cytotoxiciy of Naja nubiae (Serpentes: Elapidae) and Echis ocellatus (Serpentes: Viperidae) Venoms from Sudan." Journal of Toxins 2015 (March 15, 2015): 1–7. http://dx.doi.org/10.1155/2015/167492.
Повний текст джерелаАнотація:
In Sudan, as in many African countries, no local specific antivenom is manufactured resulting in snake bite victims being treated by antivenoms imported from abroad. In the present work we measured the cytotoxic effect of the recently described spitting cobra (Naja nubiae) and the carpet viper (Echis ocellatus) snake venoms using a cell based assay. We also investigated the efficacy of four antivenoms CSL (Australia), SAIMR (South Africa), snake venom antiserum (India), and EchiTAb-Plus-ICP (Cost Rica) to neutralize the cytotoxic effect of the two venoms. The venoms resulted in a remarkable inhibition of cell viability with N. nubiae being more cytotoxic than E. ocellatus. The four antivenoms studied were effective in neutralizing N. nubiae cytotoxicity. However, only partial efficacy in neutralizing the cytotoxic effect of E. ocellatus was achieved using CSL (Australia) and SVA (India) antivenoms. Based on the cross neutralization by the four antivenoms, the Sudanese N. nubiae venom most likely has homologous epitopes with similar snakes from Australia, South Africa, India, and Cost Rica, while E. ocellatus venom from Sudan shares little homology with similar snakes from other countries.
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Enjeti, Anoop, Fiona Scorgie, Lisa Lincz, Simon Brown, Geoff Isbister, and Michael Seldon. "Circulating Microparticles in Snake Bite Patients with Microangiopathy." Blood 112, no. 11 (November 16, 2008): 1213. http://dx.doi.org/10.1182/blood.v112.11.1213.1213.
Повний текст джерелаАнотація:
Abstract Aim: To investigate circulating microparticles (MP) in snake bite patients with microangiopathy Methods: This study used samples from patients recruited to the Australian Snakebite Project (ASP) with bites from the elapid group of snakes (including brown snake, tiger snake and taipan envenoming). Severe venom induced consumption coagulopathy (VICC) was defined as patients with an international normalised ratio [INR] > 3. Microangiopathy haemolytic anaemia (MAHA) was defined as the occurrence of thrombocytopaenia and red cell fragmentation in addition to VICC. Citrated plasma samples were collected from each patient at various time points over 0.5 to 6 days after the bite. All samples were processed and stored according to a national standardized protocol. Prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen and D-dimer concentrations were measured on a Behring Coagulation System (BCS; Dade Behring, Marburg, Germany). Full blood count was measured as per routine laboratory protocol and blood films were examined by an independent pathologist. Flow cytometry was done on BD FACS Canto flow cytometer (BD Biosciences,CA,USA) with combinations of CD41a-PE (Clone HIP8, BD Biosciences, CA, USA), CD62e-APC (Clone 68-5H11, BD Biosciences, CA, USA), CD45-PE-Cy5, (Clone HI30, BD Biosciences, CA, USA) and Glycophorin-APC( Clone HIR2, BD Biosciences, CA, USA) or appropriate isotype controls in a final volume of 500 μl of PBS. The results were analysed using BD software and appropriate statistical tools. Results: A total of 14 envenomed patient-samples with MAHA were compared to 14 envenomed patient-samples without MAHA and 45 normal healthy controls. All envenomed patient-samples with envenoming had evidence for VICC. The results for circulating MP levels in the three groups are shown in the table below: Samples (number) Hb G/L Platelet count (10^9/L) Platelet MP/μL (CD41a) Endothelial MP/μL (CD62e) Red cell MP/μL (glycophorin) Healthy controls (45) 144±9.3 265 ±85 1259±959 360±104 <50 SB with MAHA (14) 85±16 35 ± 13 2815±963 <50 883±326 SB without MAHA 136±15 141 ± 75 2447±1252 <50 104±102 The red cell micropartciples in snake bite subjects with MAHA were significantly higher than those without MAHA (p=0.005) while there was no significant difference in platelet microparticle levels between the envenomed with and without MAHA (p=0.27). Interestingly, the endothelial microparticles were reduced in all snake bite samples compared to the controls. The time trend in envenomed samples with MAHA showed that marked elevation in red cell MP occurred prior to a major drop in platelet count. Discussion: Increase in levels of red cell microparticles in envenomed patients with MAHA is consistent with haemolysis. The marked increase in red cell MP which occurs prior to a drop in platelet count needs to be evaluated further. If this is a consistent finding then measuring MP at presentation could be useful as a predictive marker for MAHA in patients with snake bites. Patients with MAHA may benefit from more intensive intervention such as using fresh frozen plasma. The lack of increase and actually a decrease in endothelial microparticles in all snake bite patient-samples was an unexpected finding which is being further investigated. This suggests an alternative mechanism to microangiopathy other than endothelial damage due to the venom toxin. Thus, circulating microparticles could potentially be used to guide treatment in patients with snake bites.
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McDowell, S. B., and R. Longmore. "Atlas of Elapid Snakes of Australia." Copeia 1987, no. 3 (August 5, 1987): 824. http://dx.doi.org/10.2307/1445691.
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Minton, Sherman A. "Atlas of elapid snakes of Australia." Toxicon 25, no. 10 (January 1987): 1133. http://dx.doi.org/10.1016/0041-0101(87)90280-7.
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Verhoef, Daniël, Mark Schreuder, Ka Lei Cheung, Pieter H. Reitsma, and Mettine H. A. Bos. "Engineered Factor Xa Variants Retain Procoagulant Activity Independent of Direct Factor Xa-Inhibitors." Blood 126, no. 23 (December 3, 2015): 126. http://dx.doi.org/10.1182/blood.v126.23.126.126.
Повний текст джерелаАнотація:
Abstract The venom of the Australian Elapid snake Pseudonaja textilis contains a prothrombin-activating complex that consists of factor Xa (FXa) and factor Va (FVa) homologs which are evolutionary adapted to derail the hemostatic system of its prey, leading to runaway coagulation. These adaptations include functional resistance to inactivation by the main inhibitors of coagulation, antithrombin and activated protein C. Further studies revealed that venom FXa, unlike other FXa species, is also resistant to inhibition by direct oral FXa-inhibitors such as rivaroxaban and apixaban (Ki >1000 nM for venom FXa vs. 1 nM for human FXa). Accordingly, venom FXa is able to support thrombin generation (TG) in FX-depleted plasma spiked with pharmacological concentrations (0.4-2 μM) of these FXa-inhibitors. While human FXa-initiated TG resulted in a 8-fold prolonged lag time and a 70% reduced thrombin peak, those parameters were within normal range in venom FXa-triggered TG. Venom FX homologs produced by Elapid snakes comprise a heterogeneous insertion between His91-Tyr99 (chymotrypsin numbering) in the serine protease domain. A recent crystal structure of one of these homologs shows that this insertion is in close proximity of the active site pocket. In contrast, P. textilis liver-derived plasma FX, which, when activated, is fully inhibited by the FXa-inhibitors (Ki10 nM), lacks this structural feature. We investigated whether the His91-Tyr99 insertion is at the basis of the reduced sensitivity of venom FXa towards FXa-inhibitors. To do so, we constructed and stably expressed human-snake FX chimeras (FX-A, -B, -C) that incorporate His91-Tyr99 insertions from three venom FXa homologs. The chimeric FX variants were purified by successive ion-exchange and hydrophobic interaction chromatography steps, and FXa was generated following RVV-X-activation and size-exclusion chromatography. Evaluation of the kinetic parameters of prothrombin conversion in the presence of saturating amounts of FVa and anionic phospholipids revealed that the chimeric FXa variants exhibit an up to ~4-fold enhanced affinity for prothrombin (Km 0.11-0.29 μM) as compared to recombinant human FXa (rhFXa; Km 0.41 μM). The rate of prothrombin activation was 3-10-fold reduced (kcat 118-370 min-1 vs. 1243 min-1 for rhFXa), which may be indicative of a modified active site conformation. Consistent with this, the rate of chimeric FXa inhibition by antithrombin was impaired (kapp 0.12-0.95 x 103 M-1 s-1 vs. 4.07 x 103 M-1 s-1 for rhFXa). Furthermore, the variant that was most poorly inhibited by antithrombin (variant A) also exhibited the lowest catalytic rate of prothrombin conversion and vice versa (variant C). Conversely, apixaban or edoxaban inhibition of the FXa variants assembled into prothrombinase led to the highest Ki for chimeric variant C (2.3 or 0.3 µM), followed by variants B (1.4 or 0.2 µM), and A (0.2 or 0.006 µM) compared to rhFXa (0.004 or 0.0005 µM). Evaluation of the inhibition of uncomplexed FXa variants employing peptidyl substrate conversion revealed a similar decrease in sensitivity to the FXa-inhibitors (≤500-fold). These data suggest that insertion of the snake venom His91-Tyr99 regions indeed results in impaired engagement of the FXa active site pocket. We next assessed whether chimeric variant C, which is most resistant to inhibition by the direct FXa-inhibitors, is able to restore thrombin generation in a plasma system in the presence of apixaban or edoxaban. While rhFXa-triggered (5 nM) thrombin formation in FX-depleted plasma was inhibited by 2 μM apixaban, initiation with FXa-C (5 nM) resulted in normal thrombin generation parameters (peak thrombin 98%). In addition, the zymogen form of variant C also supported tissue factor-initiated (2 pM) thrombin generation in FX-depleted plasma with inhibitor concentrations up to 6 μM (apixaban) or 2 μM (edoxaban). Under these conditions, little if any thrombin was formed with rhFX present (peak thrombin 5%). We obtained similar results when performing these experiments in normal pooled plasma. Taken together, these results show that chimeric FX is able to restore hemostasis in plasma inhibited by the direct FXa-inhibitors, both in the zymogen as well as protease state. As such, these variants have the potential to serve as rescue therapeutic agents to overcome the effect of FXa-inhibitors in case of potential life-threatening bleeding events or emergency surgical interventions. Disclosures Bos: Bayer Hemophilia Awards: Research Funding.
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Bos, Mettine H. A., Michael Boltz, Liam St Pierre, John de Jersey, Paul P. Masci, Martin L. Lavin, and Rodney M. Camire. "Evolutionary Adaptation of Factor V from the Venom of the Common Brown Snake into a Potent Procoagulant." Blood 112, no. 11 (November 16, 2008): 586. http://dx.doi.org/10.1182/blood.v112.11.586.586.
Повний текст джерелаАнотація:
Abstract Some of the most toxic snakes in the world are those from the Australian Elapid family, including the three most venomous land snakes Inland Taipan, Coastal Taipan, and Common Brown snake. Their venom is strongly procoagulant and they are the only species known to have acquired a powerful prothrombin activator in their venom, which consists of a factor Xa (FXa)-like and factor V (FV)-like component. Venom-derived FV (pt-FV) from the Common Brown snake P. textilis shares 44% sequence homology with mammalian FV and has a similar domain organization. Remarkably, the B domain length of pt-FV is dramatically shortened compared to human FV (46 vs. 836 aa). This adaptation provides a unique opportunity to gain new insight into the function of the B domain and to examine the mechanistic basis for the strong procoagulant nature of the venom-derived prothrombinase complex. Pt-FV was expressed in BHK cells, purified, and characterized in functional assays employing FXa purified from P. textilis venom (pt-FXa). SDS-PAGE analysis revealed that pt-FV migrated as a single chain protein (~180 kDa). Thrombin completely processed pt-FV to pt-FVa, yielding the characteristic heavy and light chains. Surprisingly, pt-FVa migrated as a single band on a non-reducing gel, indicating that the heavy and light chains are connected by a unique disulfide bond. Functional analysis of prothrombin and prethrombin-1 conversion using a purified component assay in the presence of pt-FXa and negatively charged phospholipids revealed that pt-FV exhibits kinetic parameters comparable to human prothrombinase. Proteolytic processing of single chain pt-FV to the heterodimer did not significantly increase cofactor activity, indicating that pt-FV is expressed as a constitutively active cofactor that has bypassed the normal requirement for proteolytic activation. These results were confirmed using an uncleavable variant, pt-FV-QQ. We speculate that the mechanistic basis for this constitutive cofactor activity is related to the absence of a key cluster of conserved B domain residues, which we have recently shown to play an important role in maintaining FV as an inactive procofactor (JBC2007;282:15033). Additional experiments revealed that the pt-FV–pt-FXa complex does not require a membrane surface to optimally function, as the kinetics of prethrombin-1 activation were equivalent in the presence or absence of membranes. Binding measurements indicated that this was due to the high affinity interaction (Kd ~8 nM) of pt-FV with pt-FXa in solution. Interestingly, human FVa did not bind soluble pt-FXa with high affinity, suggesting that pt-FXa binding involves unique molecular features on pt-FV. Additional studies revealed that pt-FV does not lose activity following incubation with high concentrations of activated protein C (APC), even though the pt-FV heavy chain was fully proteolyzed. Collectively, our findings provide new insights into FV structure/function as well as a biochemical rationale for the powerful procoagulant nature of the prothrombinase complex from P. textilis venom. Remarkably, pt-FV has acquired at least three gain of function elements: first, it is constitutively active and as such the first example of a naturally occurring active FV variant. Second, pt-FV has a unique conformation as it bypasses the normal requirement for a membrane surface to achieve high affinity FXa binding. Finally, pt-FV is functionally resistant to APC which could be due to its unique disulfide bond. Taken together, venom-derived P. textilis FV represents an exceptional example of a protein that has adapted into a potent biological weapon for host defense and to incapacitate prey. Uncovering the mechanistic details of these gain of function elements will provide a new level of understanding of FV/FVa function.
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Madsen, T., and R. Shine. "Toxicity of a tropical Australian frog, Litoria dahlii, to sympatric snakes." Wildlife Research 21, no. 1 (1994): 21. http://dx.doi.org/10.1071/wr9940021.
Повний текст джерелаАнотація:
Although Litoria dahlii is one of the most abundant frog species of floodplain habitats in tropical Australia, it is rarely eaten by snakes. Force-feeding trials showed that L. dahlii is highly toxic to snakes: ingestion of even a single large frog was potentially fatal for pythons (Liasis childreni and Liasis fuscus), colubrids (Dendrelaphispunctulatus and Stegonotus cucullatus) and elapids (Acanthophis praelongus and Demansia atra). Only one species, the keelback, Tropidonophis mairii (Colubridae), could consume these frogs without ill effects. Keelbacks were also the only snakes recorded to eat these frogs in the wild. The fact that these abundant tropical frogs are highly toxic to most snakes, and generally not eaten by them, suggests that the anurophagous snakes of the Australian tropics assess amphibian chemical defences before consuming their prey. Thus, these snakes may be better-able to deal with the invasion of cane toads, Bufo marinus, than has been generally supposed.
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Aubret, Fabien, Xavier Bonnet, David Pearson, and Richard Shine. "How can blind tiger snakes (Notechis scutatus) forage successfully?" Australian Journal of Zoology 53, no. 5 (2005): 283. http://dx.doi.org/10.1071/zo05035.
Повний текст джерелаАнотація:
On a small island off south-western Australia, tiger snakes (Notechis scutatus, Elapidae) continue to survive, feed, grow and reproduce successfully after being blinded by seagulls defending their chicks. We propose two alternative hypotheses to explain this surprising result: either vision is of trivial importance in tiger snake foraging, or the blinded snakes survive on a diet of abundant immobile prey that cannot escape their approach. Laboratory studies in which we blindfolded snakes falsified the first hypothesis: snakes that were unable to see had great difficulty in capturing mobile prey. Field data support the second hypothesis: blind snakes feed almost entirely on seagull chicks, whereas normal-sighted animals also took fast-moving prey (lizards and mice). Thus, the ability of tiger snakes on Carnac Island to survive without vision is attributable to the availability of abundant helpless prey (seagull chicks) in this insular ecosystem.
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Whitaker, P. B., and R. Shine. "Responses of free-ranging brownsnakes (Pseudonaja textilis : Elapidae) to encounters with humans." Wildlife Research 26, no. 5 (1999): 689. http://dx.doi.org/10.1071/wr98042.
Повний текст джерелаАнотація:
Eastern brownsnakes (Pseudonaja textilis) are large (to 2 m), slender, dangerously venomous elapid snakes that cause significant human mortality. We recorded the responses of free-ranging brownsnakes to 455 close encounters with a human observer, using 40 snakes implanted with miniature radio-transmitters, plus encounters with non-telemetered animals. Our study area (near Leeton in south-eastern Australia) is typical of many of the agricultural landscapes occupied by P. textilis. Contrary to public opinion, the snakes were rarely aggressive. About half of the encounters resulted in the snake retreating, and on most other occasions they relied on crypsis. Snakes advanced towards the observer on only 12 occasions (<3% of encounters) during initial approach, and only three of these advances were offensive. The snakes’ responses to an approach depended on the observer’s appearance (e.g. snakes were more likely to ignore an observer wearing light rather than dark shades of clothing) and behaviour (e.g. snakes were more likely to advance if approached rapidly, and touched immediately). Snakes were more likely to retreat if they were sub-adult rather than adult, if they were warm, or if they had been moving prior to an encounter. Weather conditions (air temperature, wind velocity and cloud cover) also influenced the snakes’ responses, as did season and time of day. The snakes’ response was relatively predictable from information on these factors, enabling us to suggest ways in which people can reduce the incidence of potentially fatal encounters with brownsnakes. ‘Snakes are first cowards, next bluffers, and last of all warriors’ (Pope 1958)
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Shine, Richard, Jonathan K. Webb, Mark Fitzgerald, and Joanna Sumner. "The impact of bush-rock removal on an endangered snake species, Hoplocephalus bungaroides (Serpentes : Elapidae)." Wildlife Research 25, no. 3 (1998): 285. http://dx.doi.org/10.1071/wr97022.
Повний текст джерелаАнотація:
We examined the impact of habitat degradation (removal of surface rocks) on an endangered snake species (Hoplocephalus bungaroides, Elapidae) at 23 sites in south-eastern Australia, by quantifying the impact of rock removal on (i) the availability of suitable shelter-sites for the snakes and their major prey species (the velvet gecko, Oedura lesueurii), and (ii) the numbers of snakes and geckos. Our survey showed that both the snakes and the geckos prefer rocks lying on other rocks, rather than on soil, and select rocks of particular sizes. The rocks removed by bush-rock collectors overlap considerably in size (diameter and thickness) and substrate (rock on rock) with those used by broad-headed snakes and velvet geckos. Multivariate path analysis suggests that population densities of broad-headed snakes (as measured by capture rates) may be determined primarily by gecko numbers, which in turn depend upon availability of suitable rocks. In some sites, rock numbers were substantially reduced by anthropogenic disturbance. Thus, our survey data suggest that bush-rock removal has contributed to the endangerment of H. bungaroides.
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Du, Weiguo, Jonathan K. Webb, and Richard Shine. "Heat, sight and scent: multiple cues influence foraging site selection by an ambush-foraging snake Hoplocephalus bungaroides (Elapidae)." Current Zoology 55, no. 4 (August 1, 2009): 266–71. http://dx.doi.org/10.1093/czoolo/55.4.266.
Повний текст джерелаАнотація:
Abstract Most mobile organisms respond to multiple cues when selecting habitat types, and laboratory experiments that manipulate only single cues may fail to reveal the true complexity of habitat-selection behaviour. In south- eastern Australia, broad headed snakes Hoplocephalus bungaroides (Elapidae) lie in wait under sun-warmed rocks to ambush velvet geckos Oedura leseuerii (Gekkonidae). Previous laboratory work has shown that both the geckos and the snakes actively select hotter rather than colder rocks, and that the snakes actively select rocks scented by geckos. We manipulated rock temperature and the presence of two types of cues from geckos (chemical and visual information) to clarify the causal basis for foraging site selection by the juveniles of this snake. When given a choice between cold lizard-scented rocks and hot unscented rocks, our captive snakes gave a higher priority to lizard scent than to temperature. The snakes also selected shelter-sites that provided visual as well as scent cues from lizards, rather than shelter-sites with scent cues alone. Thus, although broad-headed snakes show a direct preference for hotter rather than colder rocks in the laboratory, their choice of foraging site in the field may also be influenced by the presence of scent cues from prey. Our laboratory results suggest that habitat selection by broad-headed snakes may be more complex than has been suggested by previous single-factor laboratory trials.
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Taggart, Patrick L., Lucy Woolford, Nathan Dunstan, Luke Allen, Melanie Buote, and Scott A. Lindsay. "Cutaneous Chromatophoromas in Four Species of Australian Elapid Snake." Journal of Comparative Pathology 183 (February 2021): 33–38. http://dx.doi.org/10.1016/j.jcpa.2020.12.005.
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Keogh, J. Scott, Jonathan K. Webb, and Richard Shine. "Spatial genetic analysis and long-term mark–recapture data demonstrate male-biased dispersal in a snake." Biology Letters 3, no. 1 (November 28, 2006): 33–35. http://dx.doi.org/10.1098/rsbl.2006.0570.
Повний текст джерелаАнотація:
Dispersal is an important life-history trait, but it is notoriously difficult to study. The most powerful approach is to attack the problem with multiple independent sources of data. We integrated information from a 14-year demographic study with molecular data from five polymorphic microsatellite loci to test the prediction of male-biased dispersal in a common elapid species from eastern Australia, the small-eyed snake Rhinoplocephalus nigrescens . These snakes have a polygynous mating system in which males fight for access to females. Our demographic data demonstrate that males move farther than females (about twice as far on average, and about three times for maximum distances). This sex bias in adult dispersal was evident also in the genetic data, which showed a strong and significant genetic signature of male-biased dispersal. Together, the genetic and demographic data suggest that gene flow is largely mediated by males in this species.
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UKUWELA, KANISHKA D. B., KATE L. SANDERS, and BRYAN G. FRY. "Hydrophis donaldi (Elapidae, Hydrophiinae), a highly distinctive new species of sea snake from northern Australia." Zootaxa 3201, no. 1 (February 21, 2012): 45. http://dx.doi.org/10.11646/zootaxa.3201.1.3.
Повний текст джерелаАнотація:
A new species of viviparous sea snake, Hydrophis donaldi sp. nov. (Hydrophiinae), is described from the Gulf of Carpen-taria, northern Australia. Molecular analyses reveal this species as a deeply divergent lineage within the Hydrophis sub-group, and separate it from all other sampled taxa by fixed nucleotide substitutions at three independent mitochondrial andnuclear loci. The new species is assigned to Hydrophis based on the current morphological diagnosis of this large but pa-raphyletic genus, and is distinguished from all other Hydrophis species and closely allied genera by a combination of mor-phological characters relating to scalation, colour pattern and osteology. Using current keys for sea snakes, H. donaldi sp.nov. might be mistaken for H. coggeri, H. sibauensis or H. torquatus diadema but it is readily distinguished from thesespecies by a higher number of bands on the body and tail, lower ventral count, strongly spinous body scales, and a wider,more rounded head. Sea snakes have been sampled intensively in the Gulf of Carpentaria due to their vulnerability to by-catch in the region’s commercial prawn-trawl fisheries. That this highly distinctive new species has evaded discovery inthe region until now is surprising, but might be explained by its habitat preferences. All known specimens of H. donaldi sp. nov. were found in estuarine habitats that are relatively poorly surveyed and are not targeted by commercial fisheries.
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Jackson, Timothy, Kartik Sunagar, Eivind Undheim, Ivan Koludarov, Angelo Chan, Kate Sanders, Syed Ali, Iwan Hendrikx, Nathan Dunstan, and Bryan Fry. "Venom Down Under: Dynamic Evolution of Australian Elapid Snake Toxins." Toxins 5, no. 12 (December 18, 2013): 2621–55. http://dx.doi.org/10.3390/toxins5122621.
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Michael, Damian R., and David B. Lindenmayer. "Diplodactylus tessellatus Gunther, 1875 (Squamata: Diplodactylidae), Parasuta dwyeri Greer, 2006 and Suta suta Peters, 1863 (Squamata: Elapidae): distribution extension in the Murray catchment of New South Wales, South-eastern Australia." Check List 7, no. 5 (September 1, 2011): 578. http://dx.doi.org/10.15560/7.5.578.
Повний текст джерелаАнотація:
We present new records of the Diplodactylid lizard Diplodactylus tessellatus and Elapid snakes Parasuta dwyeri and Suta suta for the Murray Catchment Management Area of New South Wales, south-eastern Australia. These records extend the distribution of these species by approximately 55 km and 45 km south-eastward (D. tessellatus and S. suta respectively) and 74 km north-westward (P. dwyeri).
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Wolfe, Ashleigh K., Patricia A. Fleming, and Philip W. Bateman. "Impacts of translocation on a large urban-adapted venomous snake." Wildlife Research 45, no. 4 (2018): 316. http://dx.doi.org/10.1071/wr17166.
Повний текст джерелаАнотація:
Context Translocation as a tool for management of nuisance or ‘problem’ snakes near urban areas is currently used worldwide with limited success. Translocated snakes experience modified behaviours, spatial use and survivorship, and few studies have investigated the impacts of translocation within a metropolitan area. Aims In the present study, we investigated the impacts of translocation on the most commonly encountered snake in Perth Western Australia, the dugite (Pseudonaja affinis, Elapidae), by comparing the space use of resident and translocated snakes. Methods We captured 10 dugites and attached telemetry packages, composed of a radio-telemetry transmitter and global positioning system (GPS) data-logger, externally to their tails. Snakes were either released within 200 m of their initial capture sites (residents, n = 6) or moved to new unconnected habitat at least 3 km away (translocated, n = 4). Spatial-use data were analysed using general linear models to identify differences between resident and translocated dugites. Key results Translocation influenced space use of dugites and detrimentally affected their survivorship. Translocated snakes had larger activity ranges than did residents, and there was a trend towards travelling greater distances over time. Mortality for all snakes was high: 100% for translocated snakes, and 50% for residents. Conclusions Urban dugites face many threats, and snakes were negatively affected by translocation. The GPS technology we used did not improve the quality of the data over traditional radio-telemetry methods, owing to the cryptic nature of the snakes that spent much of their time under cover or underground. Implications These findings support the growing body of evidence that translocating ‘problem’ snakes is a not a humane method of animal management, and alternatives such as public education, may be more appropriate.
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Rohr, Detlef H., and Brian S. Malone. "Activity times and body temperature in Australian copperheads (Serpentes : Elapidae)." Australian Journal of Zoology 49, no. 3 (2001): 223. http://dx.doi.org/10.1071/zo01018.
Повний текст джерелаАнотація:
Local climatic conditions influence the way in which ectotherms regulate their body temperature and activity. We examined correlations between local climatic conditions, body temperature and activity in adult, basking lowland copperheads (Austrelaps superbus) from two localities (warm-temperate versus cool-temperate) in south-eastern Australia. We also collected data from highland copperheads (Austrelaps ramsayi) at a locality with cold-temperate climate. We found that across the active season, mean body temperatures were similar among localities (approximately 27˚C) irrespective of species. In contrast, activity times differed. Cool-temperate A. superbus emerged earlier in spring and in the morning and retreated earlier in the evening and in autumn than their conspecifics from the warm-temperate locality. Spring emergence was correlated with yearly fluctuations in thermal conditions, suggesting that activity times depend on environmental temperatures. Predator–prey interactions influenced body temperature and activity to some extent in spring when warm-temperate A. superbus with relatively low body temperatures (as low as 18.5˚C) were captured around ponds in which they had been foraging for frogs. Austrelaps ramsayi from the cold-temperate locality not only displayed a later emergence in spring and reduced daily activity times compared with warm and cool-temperate A. superbus but also compared with A. ramsayi, as reported from a warmer locality in eastern Australia. These data indicate that activity times vary on a geographic basis while snake body temperatures largely remain inflexible. The surprising exception was that cold-temperate A. ramsayi retreated later in autumn than cool-temperate A. superbus, and at that time they showed body temperatures as low as 12.5˚C, well below those we had recorded for A. superbus. We suggest that A. ramsayi retreat later in autumn because they need to extend their reproductive season and that this is mediated via adaptive changes in the critical minimum body temperature, as has been reported for other snakes.