Effects of stocking on the genetic structure of brown trout,Salmo trutta,in Central Europe inferred from mitochondrial and nuclear DNA markers

Abstract Stocking has had a considerable effect on wild brown trout, Salmo trutta L., populations throughout Europe. To elucidate this impact and to outline further management strategies, the genetic structure of 25 wild populations and five hatchery stocks from Czech Republic and Slovakia were analysed using mitochondrial (control region) and nuclear DNA (microsatellites, LDH‐C1*) markers. Stocking practices have caused massive hybridisation between the Atlantic and Danube brown trout strains in the central Danube basin and have lead to a loss of among‐population divergence in Slovakia and the eastern part of Czech Republic. Comparison with studies from neighbouring countries revealed substantial differences in haplotype, allele frequencies and genetic diversity across Central Europe. Differences in stocking management and origin of breeding stocks appear to be crucial factors for the spatial variability of the genetic structure of brown trout.     

Mycobacterium ulcerans infections in two horses in south-eastern Australia

Two horses were diagnosed as having Mycobacterium ulcerans infections. The first was a 21-year-old Quarterhorse-cross mare living in Mallacoota (a coastal town near the border of New South Wales and Victoria, Australia) that presented with lichenification, hair-loss and oedema on a fetlock, which subsequently ulcerated, as well as a non-healing ulcer on the wither. The second horse was a 32 year-old Standardbred gelding from Nicholson, near Bairnsdale, Victoria, that had an ulcerated lesion on its caudal thigh. Histologically, there were characteristic changes seen with M. ulcerans infections in other species, including extensive necrosis without associated granulomatous inflammation. The organisms were seen in Ziehl-Neelsen-stained smears or sections of the lesions from both horses and were isolated in culture from the first horse. A definitive diagnosis was provided by real-time polymerase chain reaction targeting the M. ulcerans-specific insertion sequence, IS2404. Delayed identification of the infectious agent in the first case led to the use of suboptimal antimicrobial therapy, resulting in failure to control the infection and the horse was subsequently euthanased. The second horse was successfully treated following surgical debulking of the centre of the lesion and one session of aggressive cryosurgery. Mycobacterium ulcerans should be considered in the differential diagnosis of unexplained lichenification with oedematous and ulcerated skin lesions in horses living in regions where this organism is endemic.     

Protactinium-231 and thorium-230 abundances and high scavenging rates in the western arctic ocean

The Canadian Basin of the Arctic Ocean, largely ice covered and isolated from deep contact with the more dynamic Eurasian Basin by the Lomonosov Ridge, has historically been considered an area of low productivity and particle flux and sluggish circulation. High-sensitivity mass-spectrometric measurements of the naturally occurring radionuclides protactinium-231 and thorium-230 in the deep Canada Basin and on the adjacent shelf indicate high particle fluxes and scavenging rates in this region. The thorium-232 data suggest that offshore advection of particulate material from the shelves contributes to scavenging of reactive materials in areas of permanent ice cover.     

Prevalence of Candidatus Mycoplasma haemolamae,bovine viral diarrhoea virus,and gastrointestinal parasitism in a sample of adult New Zealand alpaca (Vicugna pacos)

AIM: To determine the prevalence of infection with Candidatus Mycoplasma haemolamae (Mhl), antibodies to bovine viral diarrhoea virus (BVDV), and BVDV antigen, and the prevalence of animals with elevated faecal nematode egg counts (FEC) in a sample of adult New Zealand alpaca (Vicugna pacos).

METHODS: Blood samples were obtained from 175 alpaca, collected from 15 farms around New Zealand, and from 31 samples sent to a diagnostic laboratory for routine haematology. Blood smears (n=170) were examined microscopically for the presence of haemoplasma, and DNA was extracted from whole blood (n=206) for real-time PCR testing for Mhl. Packed cell volume (PCV) was determined for 193 samples. Serum samples (n=195) were tested for BVDV antibody using ELISA, and for BVDV antigen using a real-time PCR assay. Faecal samples were collected from 143 animals; FEC were measured, and samples pooled for larval culture.

RESULTS: No haemoplasma organisms were present on blood smear examination. Of the 206 blood samples, two (from the same farm) were positive for Mhl by real-time PCR testing, giving a prevalence of infection with Mhl of 0.97%. Of the 195 serum samples tested, four (2.1%) were positive for antibodies to BVDV; animals with BVDV antibodies were from 3/15 (20%) farms, none of which farmed cattle. None of the serum samples were positive by PCR for BVDV antigen. The median FEC was 50?epg (min 0, max 4,700), with 55/143 (38.5%) samples having 0?epg, and 33/143 (23.1%) having ≥250?epg. Haemonchus spp. were the most common nematodes present in faecal larval cultures from the North Island. Log₁₀ FEC was negatively associated with PCV (p=0.02), and was higher in males than females (p<0.001), and in animals that were positive compared with negative for Mhl (p=0.022).

CONCLUSIONS AND CLINICAL RELEVANCE: The number of alpaca infected with Mhl was low, as was the seroprevalence of BVDV. Gastrointestinal parasitism was, however, a common finding in this sample of New Zealand alpaca.     

New infection with Corynebacterium pseudotuberculosis reduces wool production

SUMMARY The effect of natural Corynebacterium pseudotuberculosis infection on wool production and quality in sheep was examined in light of evidence that artificial C pseudotuberculosis infection causes wool production loss. A toxin ELISA was used to identify sheep that had been infected with C pseudo tuberculosis. Greasy and clean fleece weights and fibre diameter were compared in infected and uninfected sheep. C pseudotuberculosis infection caused a 3.8 to 4.8% decrease in greasy wool production and a 4.1 to 6.6% decrease in clean wool production. C pseudotuberculosis infection did not affect fibre diameter. The effects of caseous lymphadenitis (the disease caused by C pseudotuberculosis infection) cause an annual loss of about $17 million in wool production to the Australian wool industry.     

Immunisation against ovine caseous lymphadenitis: correlation between Corynebacterium pseudotuberculosis toxoid content and protective efficacy in combined clostridial-corynebacterial vaccines

Groups of sheep were dosed with vaccines containing Corynebacterium pseudotuberculosis toxoid combined in varying amounts with 5 clostridial antigens. Resistance of the sheep to infection with C pseudotuberculosis was tested at 1, 6 and 12 months after vaccination by infection with pus from ovine lymph glands actively infected with C pseudotuberculosis. The outcome was assessed 3 months after challenge by slaughter and inspection of the sheep for caseous lymphadenitis lesions. Protection was demonstrated by a significant reduction in the proportion of immunised sheep exhibiting lesions compared with control sheep, and by fewer abscesses in affected immunised sheep than in affected control sheep. A positive correlation was found between amount of C pseudotuberculosis toxoid administered and degree of protection obtained. Chromatographically-purified toxoid induced essentially the same protection, suggesting that anti-toxic immunity is the major factor in protection.     

Evaluation of Trypsin Treatment on the Inactivation of Bovine Herpesvirus Type 1 on In Vitro Produced Pre-implantation Embryos

The aim of this study was to evaluate the efficiency of trypsin treatment on the inactivation of bovine herpesvirus type 1 (BoHV-1) on in vitro produced by fertilization and artificially infected bovine embryos. Bovine embryos on day 7 were exposed with 10 μl of BoHV-1, Los Angeles strain 10^7.5 TCID. These embryos and control embryos were divided in two groups: submitted to the sequential washes or to the trypsin treatment according to the International Embryo Transfer Society (IETS) guidelines. The embryos and the last washing drop of each group were used as inoculum to infect Madin Darby bovine kidney (MDBK) cells and submitted to nested PCR reaction using the primer that encodes the gene conserved region of virus glycoprotein gB. The data have shown that the control embryos and their last washing drop were negative. The exposed embryos that were treated with trypsin have shown positive results on the n-PCR and MDBK culture, and their last washing drop were negative. Our data have demonstrated that the trypsin treatment was not able to eliminate the BHV-1 of the embryos, suggesting an interaction between virus and embryo.