Diversity of Bartonella species detected in arthropod vectors from animals in Australia

A variety of Bartonella species were detected in two species of ticks and three species of fleas collected from marsupial hosts; brush-tailed bettong or woylie (Bettongia penicillata) and western barred bandicoots (Perameles bougainville) and from a rodent host; Rattus fuscipes in Western Australia. Bartonella species were detected using nested-PCR of the gltA gene and the 16S–23S ribosomal internal transcribed spacer region (ITS), and species were characterized using DNA sequencing of the 16S rRNA, gltA, rpoB, ftsZ genes and the ITS region. Bartonella rattaustraliani and B. coopersplainsensis were detected in Ixodes spp. ticks and fleas (Stephanocircus pectinipes) respectively collected from rodents. Two novel Bartonella species were detected from marsupials; Candidatus Bartonella woyliei n. sp. was detected in both fleas (Pygiopsylla hilli) and ticks (Ixodes australiensis) collected from woylies and Candidatus Bartonella bandicootii n. sp. was detected in fleas (Pygiopsylla tunneyi) collected from western barred bandicoots. Concatenated phylogenetic analysis of all 5 loci clarified the marsupial cluster of Bartonella species in Australia and confirmed the species status of these two Bartonella species in ticks and fleas from woylies and western barred bandicoots, which are classified as threatened species and are vulnerable to extinction.     

Identification of novel trypanosome genotypes in native Australian marsupials

In the present study, the occurrence and molecular phylogeny of trypanosome parasites were studied in both wild and captive marsupials from Western Australia and Queensland. Blood samples were screened by PCR at the 18S rDNA locus, and the glycosomal glyceraldehyde phosphate dehydrogenase gene. Overall, 5.3% of the blood samples were positive at the 18S rDNA locus. All positives belonged to wild-captured Western Australian individuals, where trypanosome-specific DNA was detected in 9.8% of the screened samples from wild marsupials, in common brushtail possums, and woylies. The detection rate of trypanosome DNA in these two host species was 12.5% and 20%, respectively. Phylogenetic analyses based on two loci, indicated that the possum-derived trypanosome isolates were genetically distinct, and most closely related to the Australian marsupial trypanosomes H25 from a kangaroo, and BRA2 from a bush rat. This is the first study to genetically characterise trypanosome isolates from possums. The analysis of the woylie-derived isolates demonstrated that this marsupial host can harbour multiple genotypes within the same geographical location and furthermore multiple genotypes within the same host, indicative of mixed infections. All the woylie-derived genotypes grouped with trypanosomes found in Australian marsupials, suggesting that they are more likely to belong to an endemic or Australasian trypanosome species. This is the first study to genetically characterise trypanosome isolates from possums (Trichosurus vulpecula). Although the clinical significance of these infections is currently unknown, the identification of these novel sequences may support future investigations on transmission, threats to endangered wildlife, and evolutionary history of the genus Trypanosoma.     

Alternative activation of ruminant macrophages by Fasciola hepatica

The helminth parasite, Fasciola hepatica, has a worldwide distribution and infects a wide variety of mammalian hosts, including ruminants and man. In response to infection, these hosts mount a type 2 helper (Th2) response that is highly polarized and results in the downregulation of type 1 helper (Th1) mechanisms. In a murine macrophage model F. hepatica induces alternative activation of macrophages. These macrophages differ from classically activated cells in that they preferentially use arginase instead of inducible nitric oxide synthase (iNOS) for metabolism of nitrogen. In this study we sought to characterize macrophage phenotype following stimulation of the ovine cell line MOCL7 with recombinant F. hepatica enzymes and crude parasite extracts. An in vitro model using the MOCL7 cell line was established and arginase levels in cells were used to determine the activation status of cells. Stimulation of this cell-line in vitro with F. hepatica products induces alternative activation. We have also found a chitinase-like protein in supernatants which is capable of differentiating alternatively activated from classically activated macrophages.     

Spontaneous whole brain slow potential changes during recovery from experimental neurosurgery

Prolonged, nonlocalized brain slow potential changes, frequently associated with cortical spreading depression, occur spontaneously during 5 days following brain implant surgery in rats. These potentials are accompanied by reductions in multiple nerve cell activity and reductions in behavioral motility. The method used in this study provides a tool for evaluating recovery from neurosurgical trauma or other brain injuries, and for testing procedures that facilitate or impede this process.     

A national survey to estimate the prevalence of Salmonella species among Canadian registered commercial turkey flocks.

In 1990-1991, a national survey was conducted to estimate the prevalence of Salmonella species among Canadian commercial turkey flocks. Two hundred and seventy flocks were randomly selected across Canada. The proportion sampled from each province was selected according to each province's share of the national turkey market. Samples, consisting of 12 pooled litter and four pooled dust samples, were used to determine the Salmonella status of the environment of each flock. Additionally, a one kilogram sample of feed was taken from each flock premise. Salmonella was recovered from environmental samples in 234/270 (86.7%) of flocks and from feed samples in 26/266 (9.8%) of flocks. Forty-eight different Salmonella serovars were isolated from flock environmental samples. The most prevalent serovars were S. anatum, S. hadar, S. agona, S. heidelberg and S. saintpaul which were isolated from 53/270 (19.6%), 49/270 (18.1%), 49/270 (18.1%), 42/270 (15.6%) and 34/270 (12.6%) flocks, respectively.     

Diel distribution of age-0 largemouth bass, Micropterus salmoides, in B. E. Jordan Lake, North Carolina (USA) and its relation to cover

Abstract – We used prepositioned area electrofishers (PAEs, 10×1.5 m) to assess diel differences in distribution of age-0 largemouth bass, Micropterus salmoides , in August 1992–1993 in a paired sampling design. PAEs were placed parallel to shore in an embayment of an unvegetated reservoir (B. E. Jordan Lake, North Carolina, USA). The catch per unit effort (CPUE=fish/PAE) was significantly higher at night than during the day in both years, indicating that age-0 largemouth bass exhibit nocturnal inshore movements. Age-0 largemouth bass captured inshore during day were smaller than those captured at night, indicating that movement patterns may change ontogenetically. Inshore-offshore movements of age-0 largemouth bass were significantly reduced in the presence of cover, suggesting that diel movements were influenced by specific habitat components. Diel movements likely were related to foraging, resting and predator avoidance behavior and could affect population dynamics and introduce bias in assessment programs. ^Note     

Extremophiles and their application to veterinary medicine

: Extremophiles are organisms that can grow and thrive in harsh conditions, e.g., extremes of temperature, pH, salinity, radiation, pressure and oxygen tension. Thermophilic, halophilic and radiation-resistant organisms are all microbes, some of which are able to withstand multiple extremes. Psychrophiles, or cold-loving organisms, include not only microbes, but fish that live in polar waters and animals that can withstand freezing. Extremophiles are structurally adapted at a molecular level to withstand these conditions. Thermophiles have particularly stable proteins and cell membranes, psychrophiles have flexible cellular proteins and membranes and/or antifreeze proteins, salt-resistant halophiles contain compatible solutes or high concentrations of inorganic ions, and acidophiles and alkaliphiles are able to pump ions to keep their internal pH close to neutrality. Their interest to veterinary medicine resides in their capacity to be pathogenic, and as sources of enzymes and other molecules for diagnostic and pharmaceutical purposes. In particular, thermostable DNA polymerases are a mainstay of PCR-based diagnostics.