Pseudechis Porphyriacus Research Articles

Predation of brown tree snakes ( Boiga irregularis) in Australia

We conducted a literature review to address the potential for using a native, vertebrate predator of brown tree snakes ( Boiga irregularis) as a biological control method on Guam. Both actual and potential predators were included in our review. We located two actual predators (red-bellied black snakes ( Pseudechis porphyriacus) and cane toads ( Bufo marinus)) and 55 potential predators of brown tree snakes. However, none of the native predators of brown tree snakes appear likely candidates as a biological control method on Guam due to their lack of selectivity in their feeding habits and unknown aspects of their natural history.

The envenomation syndrome caused by the Australian Red-bellied Black Snake Pseudechis porphyriacus

The Australian elapids inject venom which is characteristic of each species; and which cause characteristic and specific envenomation syndromes in human victims of snakebite. Because many of the medically significant Australian elapids look similar, when glimpsed in the field by snakebite victims, defining human envenomation syndromes with secure species identification has been a slow process. Correlations between securely identified species and the human envenomation syndromes which they produce are still evolving. The genus Pseudechis is the most widespread in Australia of the dangerous Australian elapid genera; and P. porphyriacus, the Red-bellied Black Snake, was the first terrestrial Australian elapid to be described and illustrated and the first to be the subject of experimental study. We present here five previously unreported cases of human envenomation in which the species diagnosis is secure. From these and with the perspective of a selected literature review, we describe the full envenomation syndrome of this species. Until the development of the Commonwealth Serum Laboratories’ Venom Detection Kit in 1979 and the occasional case report of victims of securely identified species, envenomation syndromes for most Australian snake species have remained indeterminate, because of the lack of professional expertise in the identification of the species involved. Symptoms of the P. porphyriacus envenomation syndrome include those of bite-site pain, nausea and vomiting, generalised pruritis, chest pain, prostration and abnormalities of taste and smell. Signs include local necrosis and scarring of tissue at the bite-site, gross inflammation of surrounding tissues and, at least in one case, epilepsy. Although envenomation by the Red-bellied Black Snake is not lethal in adults, the correct therapy is Tiger Snake antivenom, administered with judgement, taking into account knowledge of the specific envenomation syndrome of this species and the clinical status of the victim.

Characterisation of the biochemical and biological variations from the venom of the death adder species ( Acanthophis antarcticus, A. praelongus and A. pyrrhus)

We report on species variation in the venoms of the three species of death adder; the Common death adder ( Acanthophis antarcticus), the Northern death adder ( Acanthophis praelongus) and the Desert death adder ( Acanthophis pyrrhus). The venoms were found to vary in their biochemical (chromatography) and biological (PLA 2 activity, anticoagulant activity and reactivity with commercial death adder antivenom) properties. Each species produced significant differences in the profile and distribution of PLA 2 activity, when whole venom was applied to a cation-exchange Mono-S column. PLA 2 enzymes were purified from each venom and termed acanthoxin B (from A. praelongus), acanthoxin C (from A. pyrrhus) and the previously characterised acanthoxin A (from A. antarcticus). Acanthoxin B and C showed lower enzymatic activities than acanthoxin A (4.0, 13.7 and 23.9 μmol of phospholipid hydrolyzed/min/mg protein, respectively). N-terminal sequencing revealed acanthoxin B to share highest homology with the numerous PLA 2 isozymes (Pa-12C, Pa-1G, Pa-12A) from the King brown snake ( Pseudechis australis) and Acanthin I from the Common death adder. Similar to acanthoxin A, acanthoxin C showed highest homology with Acanthin I/II, and pseudexin A-chain from the Red-bellied black snake ( Pseudechis porphyriacus). Whole venom from A. antarcticus, A. praelongus and A. pyrrhus each showed weak anticoagulant activity (being able to prolong coagulation of the plasma for 107, 220 and 195 s, respectively). By immunodiffusion, each venom produced precipitation bands against commercial death adder antivenom.

Systemic Fusarium Infection in Two Snakes, Carpet Python, Morelia spilota variegata and a Red-bellied Black Snake, Pseudechis porphyriacus

ABSTRACT Two snakes, a carpet python, Morelia spilota variegata and a red-bellied black snake, Pseudechis porphyriacus, developed ischemic necrosis of the tail that was associated with intravascular dissemination of a Fusarium sp. infection.

Snake Bite, Rhabdomyolysis, and Renal Failure

APPROXIMATELY 5 million snake bites, scorpion stings, and anaphylactic reactions to insect stings occur worldwide annually, causing over 100,000 human deaths each year.1 Snake bites are estimated to cause 30,000 deaths annually in Asia and 1,000 deaths each in Africa and South America. By contrast, in Australia and the United States, the number of deaths is minimal. The animal toxin can cause a spectrum of effects, from local reaction with pain and swelling to severe systemic response and vital organ involvement. Intravascular hemolysis, disseminated intravascular coagulation, rhabdomyolysis, and muscular paralysis are common and can lead to or contribute to devastating hemodynamic effects. Myoglobinuria and hemoglobinuria are often observed. In the tropics, animal toxins are an important cause of rhabdomyolysis. Insect stings (wasps, hornets, and bees) and snake bites are the most common cause of myoglobinuric acute renal failure (ARF). Examination of renal biopsy specimens using immunoperoxidase staining techniques has revealed myoglobin in the renal tubules of 60% of patients with various tropical diseases, yet clinical myoglobinuria is observed in only 9%. Snakes known to have toxins with myotoxicity include Notechis scutatus (Australian tiger snake), Oxyuranus scutellatus (Australian Taipan snake), Bungarus multicinctus (Taiwanese krait), Bungarus caeruleus (Indian krait), Crotalus durissus terrificus (South American rattlesnake), Micropechis ikeheka (small-eyed snake of New Guinea), Pseudechis australis (Mulga snake), Pseudechis colletti (Collett’s snake), Pseudechis affinis (Dugite snake), Pseudechis porphyriacus (red-bellied black snake), Pseudonaja textitis (common brown snake), Tropidechis carinatus (rough-scaled snake), Austrelaps superbus (copperhead), Cryptophis nigrescens (smalleyed snake), Vipera russelli pulchella (Sri Lankan Russell’s viper), and sea snakes. All myotoxic snake venoms contain phospholipase A2, which is responsible for the rhabdomyolysis. The venoms also have neurotoxin components. Some have presynaptic effects, while a few have predilection for postsynaptic action. Postsynaptic neurotoxins account for approximately 60% of the toxic protein of sea snakes (Enhydrina schistosa). Nevertheless, the clinical picture of poisoning is predominantly myotoxic rather than neurotoxic.2 Muscular pains and myoglobinuria are the most characteristic symptoms in human snake bite victims. Myalgia starts after the bite, reaches a peak a few days later, and usually lasts for 1 week. Muscular pains are associated with myoglobinuria, muscular paresis, and areflexia. Myoglobinuria lasts for approximately 1 week, while muscular paresis and areflexia can last as long as 3 weeks. ARF occurs in the majority of patients. Hyperkalemia, hyperuricemia, hypocalcemia, hyperphosphatemia, and a low ratio of serum urea nitrogen to serum creatinine concentrations are common laboratory findings. Serum creatine phosphokinase and lactate dehydrogenase levels are variable. Of clinical interest is the observation that hemodialysis in sea snake (Enhydrina schistosa) bite victims improves the muscular symptoms, including paresis. Although the clinical aspects of the Australian elapid and sea snake bites are well described, little is known about the sequential pathologic changes of the effects of myoglobinuria in the kidney. A recent renal pathologic study in mice at

AN IN VITRO STUDY OF THE EFFECTS OF VENOM OF AUSTRALIAN ELAPIDS ON MURINE SKELETAL MUSCLE AND THE PROTECTIVE EFFECT OF HOMOLOGOUS PLASMA

The venom of many dangerous Australian snakes has a myotoxic component and some are strongly myolytic. The myotoxicity of venom of seven Australian elapid snakes was studied to determine their relative in vitro potency in causing cell death of C2C12 cells, a myoblast cell line, and murine myotubes in mixed cell culture. The venom of Pseudechis australis proved to be the most myotoxic, Austrelaps superbus and Pseudechis porphyriacus venoms also exhibited high myotoxicity relative to the other venoms tested. The specificity of Pseudechis porphyriacus venom was tested using the human glioma cell line TC3 and was shown to exhibit a general cytotoxicity. Myotoxicity, however, was the predominant action of the venom. It has long been known that certain animals such as the mongoose (Herpestes edwardsii) are able to survive envenomation. Some species of snakes also possess this property and the neutralising factor(s) responsible for this in P. porphyriacus has been shown to be present in the serum. The protective effect of homologous plasma from P. porphyriacus venom was also studied with reference to myotoxicity and cytotoxicity. The results of this study clearly demonstrated protection by homologous plasma using a myoblast cell line, C2C12, a primary mixed cell culture and TC3 cells. While protection was clear, particularly using high concentrations of venom, it was not absolute, and homologous plasma did not afford continued protection from the effects of the venom. In the mixed cell culture experiments venom/plasma mixtures pre-incubated for 30 min were more protective than venom/plasma mixtures which were not pre-incubated, in contrast to the results of cell culture studies, which showed little difference.

Acanthoxin, a toxic phospholipase A 2 from the venom of the common death adder ( Acanthophis antarcticus)

This is the first report of a phospholipase A 2 (PLA 2) from the venom of the common death adder, Acanthophis antarcticus. Acanthoxin is a basic, monomeric PLA 2 of mol. wt 13,000, consistent with the weight of neurotoxic PLA 2s from other Australian elapids. However, preliminary ultracentrifugation experimentation has shown that it is able to undergo concentration-dependent aggregation to form dimers. It has a relatively high degree of enzymatic activity (23.93 ± 1.18 μmoles of phospholipid hydrolysed/min/mg protein), but a low level of toxicity (3.2 mg/kg, s.c.). Acanthoxin is known to exist as two isoforms (A1 and A2), both of which show a high degree of homology with numerous elapid PLA 2 neurotoxins, in particular pseudexin A from the red-bellied black snake ( Pseudechis porphyriacus).

Neutralization of tiger snake ( Notechis scutatus) venom by serum from other Australian elapids

Sera from four Australian elapids and one boidid (python) were tested for their ability to protect neonatal mice against the toxic action of tiger snake ( Notechis scutatus) venom. Of the five serum samples tested, only serum from Pseudechis australis and Pseudechis porphyriacus were capable of neutralizing the tiger snake venom. In addition, neutralization was shown to be highly variable within serum taken from individual snakes of the same species ( P. porphyriacus). Previously, only viperid and colubrid snakes have been shown to possess neutralizing factors against snake venoms.

Costs of reproduction in lizards: escape tactics and susceptibility to predation

Increased basking and reduced agility in gravid female southern water skinks (Eulamprus tympanum) suggest that they will be more vulnerable to predators. However, gravid females shift their anti-predator tactics towards crypsis, by allowing potential predators (such as a human observer) to approach more closely than do males and non-gravid females. Gravid females were taken no more frequently than were non-gravid females or males when exposed to two types of natural predators, birds (kookaburra, Dacelo gigas) or snakes (common blacksnakes, Pseudechis porphyriacus) in field enclosures. Both these results suggest that the vulnerability of potential prey in this system is determined by the predator's probability of detecting a potential prey item, not its probability of capturing the prey item after detection. Hence, laboratory-based measures of performance demonstrating reduced escape speed may sometimes have little relevance to actual fitness under field conditions, if the probability that an animal will be taken by a predator depends primarily on whether or not it is seen, rather than on how quickly it can escape.

Why do Larger Snakes Eat Larger Prey Items?

Field collections of snakes often reveal a correlation between the body size of a snake and the size of its prey. Such a correlation could result from biases in (1) encounter rates with prey items of different sizes (especially in aquatic or creviceforaging species, in which smaller prey may be inaccessible to larger snakes), (2) prey choice, (3) ability to capture or handle prey, or (4) prey-swallowing ability. Field data showed that larger diamond pythons (Morelia spilota Lacapede, Boidae) took larger mean and maximum prey sizes, whereas prey mass did not correlate significantly with predator size in blacksnakes (Pseudechis porphyriacus Shaw, Elapidae). Minimum prey sizes increased little, if at all, in larger snakes of either species. Blacksnakes generally took much smaller prey items than did sympatric pythons. Laboratory trials with these two species showed that snakes with larger heads could eat larger prey, and eat prey of a given size more rapidly (and using fewer mandibular movements) than could snakes with smaller heads. Large blacksnakes were unable to enter narrow crevices to obtain prey items. Pythons could ingest much larger prey items than could blacksnakes. The rate of food intake for blacksnakes of all body sizes was highest with small prey items, whereas pythons (especially larger specimens) were more efficient with larger prey items. This fits well with field observations showing that blacksnakes of all body sizes eat small prey items, whereas pythons (especially larger specimens) consume larger prey items. The relationships between prey and predator size observed in the field are probably due to a combination of factors. Differential encounter rates, active selection of prey sizes and gape limitation may all be important influences on dietary composition in snakes. Key-words: Boidae, Elapidae, gape limitation, optimal foraging, predation, prey choice, prey size, python, snake

Sexual Dimorphism and Dietary Divergence: Differences in Trophic Morphology between Male and Female Snakes

Although the evolution of sexual dimorphism is most commonly ascribed to sexual selection, ecological divergence between the sexes may also be important. Significant differences between the sexes in head size relative to body length are common among snakes, and apparently are not attributable to sexual selection. If head-size dimorphism has evolved because it enables males and females to eat different prey sizes, then one might expect that: 1) heads of male and female snakes should differ in shape as well as size; 2) this difference should be greatest in feeding structures, especially those that constrain maximum ingestible prey size; and 3) such trophic structures should be disproportionately larger in the sex with the larger head. We examined relative proportions of different components of the head in cleared-and-stained skulls of four snake species showing sexual dimorphism: Acrochordus arafurae (Acrochordidae), Dendrelaphis punctulatus (Colubridae), Pseudechis porphyriacus (Elapidae), and Laticauda colubrina (Laticaudidae). Discriminant Function Analysis could distinguish >95% successfully between male and female heads in all four species. This dimorphism in head shape was primarily due to sex differences in trophic structures in three out of the four species. In each case, the sex with the larger head had disproportionately larger trophic structures, as predicted from the hypothesis that ecological divergence between the sexes has been important in the evolution of sexual dimorphism in snakes.

Purification, sequencing and characterization of pseudexin phospholipases A 2 from Pseudechis porphyriacus (Australian red-bellied black snake)

J. J. Schmidt and J. L. Middlebrook. Purification, sequencing and characterization of pseudexin phospholipases A 2 from Pseudechis porphyriacus (Australian red-bellied black snake). Toxicon 27, 805–818, 1989.—Pseudexin is the name given to a mixture of toxic phospholipase A 2 isoenzymes isolated from the venom of the Australian red-bellied black snake, Pseudechis porphyriacus. We found that this mixture consists of three components: pseudexins A, B and C, which we individually purified by reverse phase chromatography or by hydrophobic interaction chromatography. Pseudexins A and B had relatively low specific toxicities in mice (i.p. ld 50 of 1300 and 750 μg/kg, respectively), while C was non-toxic. All three had similar phospholipase A 2 activities (43–53 μequiv H + released/min/mg protein). The complete amino acid sequences of pseudexins A and B were determined. Amino acids were identical at 91 of the 117 residues. The first 28 residues of pseudexin C were determined, sufficient to show that C is structurally similar to A and B, but not identical with either. As judged by reactions with antisera against several other snake phospholipase A 2 toxins, pseudexins A, B and C have very similar antigenic structures. We noted extensive homology with other phospholipases.

Intraspecific Variation in Thermoregulation, Movements and Habitat Use by Australian Blacksnakes, Pseudechis porphyriacus (Elapidae)

Radiotelemetric studies of snake behavior often have been based on few animals, monitored in single study areas for short periods of time. A four-year study involving three widely separated study areas, in which 44 blacksnakes (Pseudechis porphyriacus) were radio-tracked for an average of 90 days each, revealed unexpectedly high variability in habitat use, activity levels, daily movements and activity ranges. Significant variation was documented among individual snakes, between sexes, among seasons, among years, and among study areas. The only characteristic that showed little variation was activity temperature range: active blacksnakes maintained body temperatures of 28 to 31?C over a variety of seasons, study areas, and ambient temperatures. This constancy was apparently achieved by varying behavioral characteristics, especially activity levels and times. Activity ranges varied from 0.02 ha to over 40 ha in different snakes, and were larger in males during the mating season. Reproductive activity declined or ceased in two populations during a severe drought. The behavioral flexibility exhibited by P. porphyriacus makes it difficult to describe typical behavior for this species, and suggests that many previous radiotelemetric field studies of snakes should be inter- preted with caution.

SPECIES OF OPHIONYSSUS MÉGNIN FROM AUSTRALIAN LIZARDS AND SNAKES (ACARI: DERMANYSSIDAE)

AbstractFour species of Ophionyssus have been taken from Australian lizards and snakes. New host‐records are given for O. scincorum Domrow et al.: Hemiergis decresiensis (Cuvier) (Scincidae) (South Australia); and for O. natricis (Gervais): Lacerta viridis (Laurenti) (Lacertidae), and Acanthophis antarcticus (Shaw and Nodder) and Pseudechis porphyriacus (Shaw) (Elapidae) (eastern Australia). O. ehmanni sp. n. is figured and described from Egernia striolata (Peters) (Scincidae) (South Australia). Neoliponyssus arnhemlandensis Womersley from Carlia fusca (Duméril and Bibron) (Scincidae) (Northern Territory) is restudied and newly combined with Ophionyssus.

Amino terminal analysis of pseudexin from the venom of the Australian red-bellied black snake ( Pseudechis porphyriacus)

The toxic phospholipase, pseudexin, was purified from the venom of the Australian red-bellied black snake, P. porphyriacus, and the sequence of the 15 N-terminal amino acids determined by automated sequence analysis. Pseudexin is composed of two isoenzymes with heterogeneity being observed at positions three and six. The sequence of the N-terminal portion of the two isoenzymes is: ▪

In vitro coagulant properties of venoms from Australian snakes

The procoagulant properties of venomous Australian snakes are limited to prothrombin activation. Venoms of Notechis scutatus, Tropidechis carinatus and Pseudechis porphyriacus require phospholipid, calcium and factor V to maximally activate normal prothrombin. Venoms of Pseudonaja textilis and Oxyuranus microlepidotus activate both normal prothrombin and the decarboxy form and do not require co-factors. The actions of the venom of Oxyuranus scutellatus are dependent on concentration.

Mating and Male Combat in Australian Blacksnakes, Pseudechis porphyriacus

We observed ritual combat and other agonistic behavior between male blacksnakes (Pseudechis porphyriacus) in a field population in central New South Wales. Combat bouts vary greatly in duration (2 to 30 minutes), and apparently function as male strategies to displace rival courting males. Direct attack and biting may serve to displace rival males in copulo. We briefly review published literature on male combat in snakes.

Isolation of a hemolytic, toxic phospholipase from the venom of the Australian red-bellied black snake ( Pseudechis porphyriacus)

A weak toxin was isolated from the venom of the Australian red-bellied black snake, Pseudechis porphyriacus, by ion-exchange chromatography on Bio-Rex 70, followed by gel filtration on Sephadex G-50. The toxin, pseudexin, accounts for 25% of the venom and has an ld 50 (i.p.) of 480 μg/kg mouse. It is a polypeptide of 143 amino acid residues and has a formula weight of 16,659. Pseudexin has phospholipase A (phosphatidate acyl-hydrolase, EC 3.1.1.4) activity. Modification of the toxin with p-bromophenacyl bromide resulted in a 99·9% loss of phospholipase activity and a reduction of its toxicity. The toxin, like other phospholipases, caused indirect hemolysis of washed erythrocytes. In addition, pseudexin directly hemolysed erythrocytes under conditions in which phospholipases are normally non-hemolytic.

Behavioral Thermoregulation in Australian Elapid Snakes

Behavioral thermoregulation in laboratory thermal gradients was studied in seven species of Australian snakes of the Elapidae: Acanthophis antarcticus, Austrelaps superbus, Notechis scutatus, Pseudechis porphyriacus, Pseudonaja nuchalis, P. textilis and Unechis flagellum. All species exhibited well-developed thermoregulatory behavior and controlled body temperatures with precision comparable to that reported for various heliothermic lizards. Temperature regulation is accomplished by shuttling and by adjustments in the snake's position or orientation while basking. Thermal preferenda of the various species range roughly between 30 and 35 C and are similar to those of other terrestrial, Temperate Zone snakes in which thermal preferences have been adequately assessed. Thermal preferenda of adult snakes appear to be higher than those of newborn or juveniles (in four species) and may vary with levels of critical thermal minima (in five species) and geographic distribution.

Thermoregulation in the Red-bellied Blacksnake, Pseudechis porphyriacus (Elapidae)

Cold Pseudechis porphyriacus aid heating by basking, flattening and tilting. When body temperatures are higher, thermoregulation is achieved by shuttling between sun and shade. A warm snake in a cooling environment frequently coils. The major factors associated with rate of temperature change in the body core were (1) horizontal gradient between body and neck, (2) posture and (3) vertical gradients from body core to body surface. The role of behavioral, physiological and physical factors in thermoregulation are discussed.