Physiological evidence for reproductive suppression in the introduced population of brown tree snakes (Boiga irregularis) on Guam

Introduced species are an increasingly pervasive problem. While studies on the ecology and behavior of these pests are numerous, there is relatively little known of their physiology, specifically their reproductive and stress physiology. One of the best documented introduced pest species is the brown tree snake, Boiga irregularis, which was introduced onto the Pacific island of Guam sometime around World War II. The snake is responsible for severely reducing Guam's native vertebrates. We captured free-living individuals throughout the year and measured plasma levels of stress and sex hormones in an effort to determine when they were breeding. These data were compared to reproductive cycles from a captive population originally collected from Guam. Free-living individuals had chronically elevated plasma levels of the stress hormone corticosterone and basal levels of sex steroids and a remarkably low proportion were reproductively active. These data coincide with evidence that the wild population may be in decline. Captive snakes, had low plasma levels of corticosterone with males displaying a peak in plasma testosterone levels during breeding. Furthermore, we compared body condition between the free-living and captive snakes from Guam and free-living individuals captured from their native range in Australia. Male and female free-living snakes from Guam exhibited significantly reduced body condition compared to free-living individuals from Australia. We suggest that during the study period, free-living brown tree snakes on Guam were living under stressful conditions, possibly due to overcrowding and overexploitation. of food resources, resulting in decreased body condition and suppressed reproduction. (C) 2004 Elsevier Ltd. All rights reserved.

The effects of haemogregarine-like parasites on brown tree snakes (Boiga irregularis) and slatey-grey snakes (Stegonotus cucullatus) in Queensland, Australia

We described the effects of haemogregarine-like parasites on the blood chemistry and health of brown tree snakes (Boiga irregularis) and slatey-grey snakes (Stegonotus cucullatus) to evaluate the potential for these parasites to be used as a form of biological wildlife control for introduced brown tree snakes on Guam. We quantified the level of parasitic infection and found no significant correlation between parasitic infection and blood chemistry (P-values ranged from 0.94 to 0.13) or snake condition (P = 0.65 and 0.40 in brown tree snakes and slatey-grey snakes, respectively). These findings indicate that haemogregarines may not be a good candidate to control brown tree snakes. However, parasitic infection in our specimens was low ( < 10%) and higher infection rates may yield significant effect on the health of these snakes. Further research should be conducted on the effects of haemogregarines to host species, the life histories of these parasites, and the potential negative effects to other fauna before blood parasites are employed as a viable biological control technique. (C) 2002 Published by Elsevier Science Ltd.

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. (C) 2002 Elsevier Science Ltd. All rights reserved.

Ultrastructure of Hepatozoon boigae (Mackerras, 1961) nov comb. from brown tree snakes, Boiga irregularis, from northern Australia

Intraerythrocytic bodies identified as haemogregarine gamonts were found in 29% of 97 brown tree snakes (Boiga irregularis) examined during a haematological survey of reptiles in Australasia during 1994-1998. The morphological characteristics of the parasites were consistent with those of Haemogregarina boigae Mackerras, 1961, although the gamonts were slightly larger and lacked red caps but contained distinctive polar grey capsules. Gamonts did not distend host cells but laterally displaced their nuclei. They were contained within parasitophorous vacuoles and possessed typical apicomplexan organelles, including a conoid, polar rings, rhoptries and micronemes. Schizonts producing up to 30 merozoites were detected in endothelial cells of the lungs of 11 snakes. The absence of erythrocytic schizogony suggests the parasites belong to the genus Hepatozoon. Electron microscopy also revealed the presence of curious encapsulated organisms in degenerating erythrocytes. These stages did not possess apical complex organelles and were surrounded by thick walls containing circumferential junctions and interposed strips reminiscent of oocyst sutures.

Phylogenetic relationships of Hepatozoon (Haemogregarina) boigae Hepatozoon sp. Haemogregarina clelandi and Haemoproteus chelodina from Australian reptiles to other Apicomplexa based on cladistic analyses of ultrastructural and life-cycle characters

The phylogeny of representative haemozoan species of the phylum Apicomplexa was reconstructed by cladistic analyses of ultrastructural and life-cycle characteristics. The analysis incorporated 4 apicomplexans previously not included in phylogenetic reconstructions: Haemogregarina clelandi from the Brisbane River tortoise (Emydura signata), Hepatozoon sp. from the slaty grey snake (Stegonotus cucullatus), Hepatozoon (Haemogregarina) boigae from the brown tree snake (Boiga irregularis), and Haemoproteus chelodina from the saw-shelled tortoise (Elseya latisternum). There was no apparent correlation between parasite phylogeny and that of their vertebrate hosts, but there appeared to be some relationship between parasites and their intermediate hosts, suggestive of parasite/vector co-evolution.

Molecular diversity in venom from the Australian Brown Snake, Pseudonaja textilis

Venom from the Australian elapid Pseudonaja textilis (Common or Eastern Brown snake), is the second most toxic snake venom known and is the most common cause of death from snake bite in Australia. This venom is known to contain a prothrombin activator complex, serine proteinase inhibitors, various phospholipase A(2)s, and pre-and postsynaptic neurotoxins. In this study, we performed a proteomic identification of the venom using two- dimensional gel electrophoresis, mass spectrometry, and de novo peptide sequencing. We identified most of the venom proteins including proteins previously not known to be present in the venom. In addition, we used immunoblotting and post-translational modification-specific enzyme stains and antibodies that reveal the complexity and regional diversity of the venom. Modifications observed include phosphorylation, gamma-carboxylation, and glycosylation. Glycoproteins were further characterized by enzymatic deglycosylation and by lectin binding specificity. The venom contains an abundance of glycoproteins with N-linked sugars that include glucose/mannose, N-acetylgalactosamine, N-acetylglucosamine, and sialic acids. Additionally there are multiple isoforms of mammalian coagulation factors that comprise a significant proportion of the venom. Indeed two of the identified proteins, a procoagulant and a plasmin inhibitor, are currently in development as human therapeutic agents.

Mimicry of host cuticular hydrocarbons by salticid spider Cosmophasis bitaeniata that preys on larvae of tree ants Oecophylla smaragdina

The salticid spider Cosmophasis bitaeniata preys on the larvae of the green tree ant Oecophylla smaragdina. Gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) reveal that the cuticle of C. bitaeniata mimics the mono- and dimethylalkanes of the cuticle of its prey. Recognition bioassays with extracts of the cuticular hydrocarbons of ants and spiders revealed that foraging major workers did not respond aggressively to the extracts of the spiders or conspecific nestmates, but reacted aggressively to conspecific nonnestmates. Typically, the ants either failed to react (as with control treatments with no extracts) or they reacted nonaggressively as with conspecific nestmates. These data indicate that the qualitative chemical mimicry of ants by C. bitaeniata allows the spiders to avoid detection by major workers of O. smaragdina.

Cloning and sequence analysis of pituitary prolactin cDNA from the northern brown bandicoot (Isoodon macrourus)

The nuclectide sequence for pituitary prolactin cDNA from the marsupial bandicoot (Isoodon macrourus) was determined by reverse transcription-polymerase chain reaction and 5'/3' rapid amplification of cDNA ends. The deduced amino acid sequence showed high sequence identity with brushtail possum prolactin (95%) and all of the expected structural features of a quadruped prolactin. A prolactin gene tree was constructed and rates of evolution calculated for bandicoot, possum, opossum and several mammalian and non-mammalian prolactins. Bootstrap analysis provided strong support for marsupials as a sister group with eutherian mammals and weak support for opossum and bandicoot as an independent grouping from the brushtail possum. The rates of molecular evolution for marsupial prolactins were comparable to the slow rate seen in the majority of quadruped prolactins that have been sequenced. (c) 2005 Elsevier Inc. All rights reserved.

Comparison of active venom components between Eastern brown snakes collected from South Australia and Queensland

The abundance and activity of the prothrombin activator (pseutarin C) within the venom of the Eastern brown snake (Pseudonaja textilis textilis) is the primary determinant of its coagulation potency. Textilinin-1, also in this venom, is a plasmin inhibitor which is thought to exert its toxic effects through the slowing of fibrinolysis. The aim of this report is to determine if there are differences in the potency of the venom from Eastern brown snakes collected from South Australia (SA) compared to those from Queensland (QLD). A concentration of 0.4 mu g/ml venom protein from six QLD specimens clotted citrated plasma in an average time of 21.4 +/- 3.3 s compared to 68.7 +/- 2.4 s for the same amount of SA venom (averaged for six individuals). The more potent procoagulant activity of the QLD venom was measured between 0.4 and 94 mu g/ml venom protein in plasma. The anti-plasmin activity of textilinin was also greater in the venom of the snakes collected from QLD, causing full inhibition of plasmin at approximately 1.88 mu g/ml of venom protein compared to approximately 7.5 mu g/ml for the SA venoms. It is concluded that geographic differentiation of the Eastern brown snakes results in significant differences venom potency.

West (side) and north (rear) elevations, public housing, Cotton Tree Housing Estate, Maroochydore

This pilot project at Cotton Tree, Maroochydore, on two adjacent, linear parcels of land has one of the properties privately owned while the other is owned by the public housing authority. Both owners commissioned Lindsay and Kerry Clare to design housing for their separate needs which enabled the two projects to be governed by a single planning and design strategy. This entailed the realignment of the dividing boundary to form two approximately square blocks which made possible the retention of an important stand of mature paperbark trees and gave each block a more useful street frontage. The scheme provides seven two-bedroom units and one single-bedroom unit as the private component, with six single-bedroom units, three two-bedroom units and two three-bedroom units forming the public housing. The dwellings are deployed as an interlaced mat of freestanding blocks, car courts, courtyard gardens, patios and decks. The key distinction between the public and private parts of the scheme is the pooling of the car parking spaces in the public housing to create a shared courtyard. The housing climbs to three storeys on its southern edge and falls to a single storey on the north-western corner. This enables all units and the principal private outdoor spaces to have a northern orientation. The interiors of both the public and private units are skilfully arranged to take full advantage of views, light and breeze.

View northeast over single story apartment, Cotton Tree Housing Estate, Maroochydore

This pilot project at Cotton Tree, Maroochydore, on two adjacent, linear parcels of land has one of the properties privately owned while the other is owned by the public housing authority. Both owners commissioned Lindsay and Kerry Clare to design housing for their separate needs which enabled the two projects to be governed by a single planning and design strategy. This entailed the realignment of the dividing boundary to form two approximately square blocks which made possible the retention of an important stand of mature paperbark trees and gave each block a more useful street frontage. The scheme provides seven two-bedroom units and one single-bedroom unit as the private component, with six single-bedroom units, three two-bedroom units and two three-bedroom units forming the public housing. The dwellings are deployed as an interlaced mat of freestanding blocks, car courts, courtyard gardens, patios and decks. The key distinction between the public and private parts of the scheme is the pooling of the car parking spaces in the public housing to create a shared courtyard. The housing climbs to three storeys on its southern edge and falls to a single storey on the north-western corner. This enables all units and the principal private outdoor spaces to have a northern orientation. The interiors of both the public and private units are skilfully arranged to take full advantage of views, light and breeze.

South (front) elevation, public housing, Cotton Tree Housing Estate, Maroochydore

This pilot project at Cotton Tree, Maroochydore, on two adjacent, linear parcels of land has one of the properties privately owned while the other is owned by the public housing authority. Both owners commissioned Lindsay and Kerry Clare to design housing for their separate needs which enabled the two projects to be governed by a single planning and design strategy. This entailed the realignment of the dividing boundary to form two approximately square blocks which made possible the retention of an important stand of mature paperbark trees and gave each block a more useful street frontage. The scheme provides seven two-bedroom units and one single-bedroom unit as the private component, with six single-bedroom units, three two-bedroom units and two three-bedroom units forming the public housing. The dwellings are deployed as an interlaced mat of freestanding blocks, car courts, courtyard gardens, patios and decks. The key distinction between the public and private parts of the scheme is the pooling of the car parking spaces in the public housing to create a shared courtyard. The housing climbs to three storeys on its southern edge and falls to a single storey on the north-western corner. This enables all units and the principal private outdoor spaces to have a northern orientation. The interiors of both the public and private units are skilfully arranged to take full advantage of views, light and breeze.

Detail of roofing and wall, Cotton Tree Housing Estate, Maroochydore

This pilot project at Cotton Tree, Maroochydore, on two adjacent, linear parcels of land has one of the properties privately owned while the other is owned by the public housing authority. Both owners commissioned Lindsay and Kerry Clare to design housing for their separate needs which enabled the two projects to be governed by a single planning and design strategy. This entailed the realignment of the dividing boundary to form two approximately square blocks which made possible the retention of an important stand of mature paperbark trees and gave each block a more useful street frontage. The scheme provides seven two-bedroom units and one single-bedroom unit as the private component, with six single-bedroom units, three two-bedroom units and two three-bedroom units forming the public housing. The dwellings are deployed as an interlaced mat of freestanding blocks, car courts, courtyard gardens, patios and decks. The key distinction between the public and private parts of the scheme is the pooling of the car parking spaces in the public housing to create a shared courtyard. The housing climbs to three storeys on its southern edge and falls to a single storey on the north-western corner. This enables all units and the principal private outdoor spaces to have a northern orientation. The interiors of both the public and private units are skilfully arranged to take full advantage of views, light and breeze.

View along western boundary; paperbark trees between private and public housing, Cotton Tree Housing Estate, Maroochydore

This pilot project at Cotton Tree, Maroochydore, on two adjacent, linear parcels of land has one of the properties privately owned while the other is owned by the public housing authority. Both owners commissioned Lindsay and Kerry Clare to design housing for their separate needs which enabled the two projects to be governed by a single planning and design strategy. This entailed the realignment of the dividing boundary to form two approximately square blocks which made possible the retention of an important stand of mature paperbark trees and gave each block a more useful street frontage. The scheme provides seven two-bedroom units and one single-bedroom unit as the private component, with six single-bedroom units, three two-bedroom units and two three-bedroom units forming the public housing. The dwellings are deployed as an interlaced mat of freestanding blocks, car courts, courtyard gardens, patios and decks. The key distinction between the public and private parts of the scheme is the pooling of the car parking spaces in the public housing to create a shared courtyard. The housing climbs to three storeys on its southern edge and falls to a single storey on the north-western corner. This enables all units and the principal private outdoor spaces to have a northern orientation. The interiors of both the public and private units are skilfully arranged to take full advantage of views, light and breeze.