Congenital toxoplasmosis in a Indo-Pacific bottlenose dolphin (Tursiops aduncus)

Toxoplasma gondii was identified in tissues of a stillborn late-term fetus from an Indo-Pacific bottlenose dolphin (Tursiops aduncus). Myocardial necrosis and nonsuppurative inflammation in the heart and nonsuppurative necrotizing encephalitis were associated with tachyzoites and tissue cysts. The diagnosis was confirmed by immunohistochemical staining with anti-T. gondii-specific polyclonal rabbit serum.     

Molecular mechanism of transforming growth factor (TGF)-beta1-induced glutathione depletion in alveolar epithelial cells. Involvement of AP-1/ARE and Fra-1

Glutathione (GSH) is a ubiquitous antioxidant in lung epithelial cells and lung lining fluid. Transforming growth factor beta1 (TGF-beta1) is a pleiotropic cytokine involved in cellular proliferation and differentiation. The level of TGF-beta1 is elevated in many chronic inflammatory lung disorders associated with oxidant/antioxidant imbalance. In this study, we show that TGF-beta1 depletes GSH by down-regulating expression of the enzyme responsible for its formation, gamma-glutamylcysteine synthetase (gamma-GCS) and induces reactive oxygen species production in type II alveolar epithelial cells (A549). To investigate the molecular mechanisms of inhibition of glutathione synthesis, we employed reporters containing fragments from the promoter region of the gamma-GCS heavy subunit (h), the gene that encodes the catalytic subunit of gamma-GCS. We found that TGF-beta1 reduced the expression of the long gamma-GCSh construct (-3802/GCSh-5'-Luc), suggesting that an antioxidant response element (ARE) may be responsible for mediating the TGF-beta1 effect. Interestingly, the electrophoretic mobility shift assay revealed that the DNA binding activity of both activator protein-1 (AP-1) and ARE was increased in TGF-beta1-treated epithelial cells. The gamma-GCSh ARE contains a perfect AP-1 site embedded within it, and mutation of this internal AP-1 sequence, but not the surrounding ARE, prevented DNA binding. Further studies revealed that c-Jun and Fra-1 dimers, members of the AP-1 family previously shown to exert a negative effect on phase II gene expression, bound to the ARE sequence. We propose a novel mechanism of gamma-GCSh down-regulation by TGF-beta1 that involves the binding of c-Jun and Fra-1 dimers to the distal promoter. The findings of this study provide important information, which may be used for the modulation of glutathione biosynthesis in inflammation.     

Feeding across the food web: The interaction between diet,movement and body size in estuarine crocodiles (Crocodylus porosus)

The estuarine crocodile (Crocodylus porosus) is an apex predator across freshwater, estuarine and coastal environments. The impact of a changing C. porosus population upon the ecosystem is unknown, but due to large ontogenetic changes in body mass (>1000‐fold) their impact may be wide reaching and substantial. Here we investigated the relationship between diet, movement and body size in a population of C. porosus inhabiting a tidal river in northern Australia. Subcutaneous acoustic transmitters and fixed underwater receivers were used to determine the activity space and movement patterns of 42 individuals (202–451 cm in total length). There was no size‐related spatial partitioning among different sized crocodiles. Large individuals (snout–vent length (SVL): 160 cm < SVL < 188.5 cm) did, however, exhibit a much larger activity space than other size classes. Diet and individual specialization was assessed using the composition of stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotopes in tissues with different turnover rates. There was a quadratic relationship between body size and δ¹⁵N, suggesting that medium‐sized individuals (110 cm < SVL < 160 cm) incorporated a greater proportion of high trophic prey into their diets than small (SVL < 110 cm) or large individuals (SVL > 160 cm). Tissue δ¹³C composition on the other hand was positively correlated with body size, indicating that different size classes were trophically linked to primary producers in different habitats. Individual‐level analyses showed that small crocodiles were generalist feeders while medium and large size classes specialized on particular prey items within the food webs they fed. The findings further our understanding of ontogenetic variation in C. porosus diet, and suggest that change in C. porosus population size or demographics may be influential at various levels across the local food web.     

Cardiac sympathetic nerve activity and ventricular fibrillation during acute myocardial infarction in a conscious sheep model

The association between cardiac sympathetic nerve activity (CSNA) and ventricular fibrillation (VF) during acute myocardial infarction (MI) has not been assessed in conscious animal models. During the first 60 min post-MI, mean blood pressure (MBP), heart rate (HR), and CSNA were recorded continuously in 20 conscious sheep. Resistant sheep (group A, n = 10) were compared with susceptible sheep (group B, n = 10) who developed fatal VF (n = 7) or sustained ventricular tachycardia (VT, n = 3). The mean time to VF/VT was 28.1 +/- 3.3 min. In group B, MBP, HR, and CSNA were averaged at each consecutive minute from baseline at 14 min before the onset of VF/VT and compared with time-matched values in group A. When compared with those of group A, indexes of CSNA burst size increased before the onset of VF/VT: burst area/minute (F(13,208) = 2.17, P = 0.01) and burst area/100 beats (F(13,208) = 1.86, P = 0.04). By contrast, burst frequency indexes were not significantly different: burst frequency (F(13,208) = 1.6, P = 0.09) and burst incidence (F(13,208) = 1.48, P = 0.13). In group A, CSNA burst area/min and burst area/100 beats did not change across this time period (F(13,117) = 0.97, P = 0.5, F(13,117) = 0.96, P = 0.7) but increased with time in group B (F(13,91) = 2.3, P = 0.01; and F(13,91) = 2.25, P = 0.01). Between-group comparisons demonstrated no differences in time of onset of ventricular ectopic beats: 18.5 (range 12-24) in group A versus 15.0 min (range 7-22) in group B (Mann-Whitney U-test, P = 0.09). Pre-MI baroreflex slopes were similar: R-R slopes were 11.8 +/- 2 and 15.6 +/- 1.1 ms/mmHg (t(18) = -1.6, P = 0.14). CSNA slopes were -1.8 +/- 0.3 and -2.3 +/- 0.2%/mmHg (t(18) = -1.4, P = 0.2). An early increase in CSNA burst size indexes (before 60 min post-MI), mediated by an excitatory sympathetic reflex, is important in the genesis of VF/VT.     

Rapid Response to Evaluate the Presence of Amphibian Chytrid Fungus (Batrachochytrium dendrobatidis) and Ranavirus in Wild Amphibian Populations in Madagascar

We performed a rapid response investigation to evaluate the presence and distribution of amphibian pathogens in Madagascar following our identification of amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd) and ranavirus in commercially exported amphibians. This targeted risk-based field surveillance program was conducted from February to April 2014 encompassing 12 regions and 47 survey sites. We simultaneously collected amphibian and environmental samples to increase survey sensitivity and performed sampling both in wilderness areas and commercial amphibian trade facilities. Bd was not detected in any of 508 amphibian skin swabs or 68 water filter samples, suggesting pathogen prevalence was below 0.8%, with 95% confidence during our visit. Ranavirus was detected in 5 of 97 amphibians, including one adult Mantidactylus cowanii and three unidentified larvae from Ranomafana National Park, and one adult Mantidactylus mocquardi from Ankaratra. Ranavirus was also detected in water samples collected from two commercial amphibian export facilities. We also provide the first report of an amphibian mass-mortality event observed in wild amphibians in Madagascar. Although neither Bd nor ranavirus appeared widespread in Madagascar during this investigation, additional health surveys are required to disentangle potential seasonal variations in pathogen abundance and detectability from actual changes in pathogen distribution and rates of spread. Accordingly, our results should be conservatively interpreted until a comparable survey effort during winter months has been performed. It is imperative that biosecurity practices be immediately adopted to limit the unintentional increased spread of disease through the movement of contaminated equipment or direct disposal of contaminated material from wildlife trade facilities. The presence of potentially introduced strains of ranaviruses suggests that Madagascar''s reptile species might also be threatened by disease. Standardized population monitoring of key amphibian and reptile species should be established with urgency to enable early detection of potential impacts of disease emergence in this global biodiversity hotspot.     

Mosquito (Diptera: Culicidae) fauna in inland areas of south-west Western Australia

Abstract  Previously existing sources of data regarding mosquitoes in inland areas of south-west Western Australia are few and qualitative in nature. This is the first attempt to quantitatively investigate mosquito fauna in this region. The existing data are reviewed and compared with the results of the quantitative surveys presented in this paper. Temporal comparisons appear to indicate that mosquito community structure in the region may have changed since the initial surveys in the 1950s from a combination of freshwater-breeding species towards a strong dominance of Aedes camptorhynchus (Thomson), a major vector of Ross River virus in southern Australia. It is speculated that this shift may have been brought about by the increasing area and severity of dryland salinity in the region over the last century, and also may increase the potential for Ross River virus disease transmission.     

The Star STING server: a multiplatform environment for protein structure analysis

Star STING is the latest version of the STING suite of programs and corresponding database. We report on five important aspects of this package that have acquired some new characteristics, designed to add key advantages to the whole suite: 1) availability for most popular platforms and browsers, 2) introduction of the STING_DB quality assessment, 3) improvement in algorithms for calculation of three STING parameters, 4) introduction of five new STING modules, and 5) expansion of the existing modules. Star STING is freely accessible at: http://sms.cbi.cnptia.embrapa.br/SMS/, http://trantor.bioc.columbia.edu/SMS, http://www.es.embnet.org/SMS/, http://gibk26.bse.kyutech.ac.jp/SMS/ and http://www.ar.embnet.org/SMS.     

Observation of unpaired substrate DNA in the flap endonuclease-1 active site

The structure- and strand-specific phosphodiesterase flap endonuclease-1 (FEN1), the prototypical 5′-nuclease, catalyzes the essential removal of 5′-single-stranded flaps during replication and repair. FEN1 achieves this by selectively catalyzing hydrolysis one nucleotide into the duplex region of substrates, always targeting the 5′-strand. This specificity is proposed to arise by unpairing the 5′-end of duplex to permit the scissile phosphate diester to contact catalytic divalent metal ions. Providing the first direct evidence for this, we detected changes induced by human FEN1 (hFEN1) in the low-energy CD spectra and fluorescence lifetimes of 2-aminopurine in substrates and products that were indicative of unpairing. Divalent metal ions were essential for unpairing. However, although 5′-nuclease superfamily-conserved active-site residues K93 and R100 were required to produce unpaired product, they were not necessary to unpair substrates. Nevertheless, a unique arrangement of protein residues around the unpaired DNA was detected only with wild-type protein, suggesting a cooperative assembly of active-site residues that may be triggered by unpaired DNA. The general principles of FEN1 strand and reaction-site selection, which depend on the ability of juxtaposed divalent metal ions to unpair the end of duplex DNA, may also apply more widely to other structure- and strand-specific nucleases.