Chalara fraxinea is an invasive pathogen in France

Decline induced by Chalara fraxinea is an emerging disease that severely affects ash stands in Europe. The disease appears to have an invasive spread from East to West of Europe in the last decade. The teleomorphic stage, Hymenoscyphus pseudoalbidus, that occurs as apothecia on ash rachis in the litter was recently described. The origin of ash decline remains unclear as a cryptic species, H. albidus, a long-established fungus in Europe, could be present in the same niche, and as in Switzerland, H. pseudoalbidus was shown to have been present long before the recent epidemic outbreak. In France, the emerging disease is very recent and clearly restrained to Northeastern France. We thus collected isolates from infected hosts and from apothecia/ash rachis both inside and outside the infected area in France in order to compare them on the basis of pathogenicity towards ash seedlings and sequences of the ITS regions and of three single-copy genes. We showed that two population types exhibiting about 2% base pair polymorphism in the sequences analysed were present in Northern France. The first type, corresponding to H. pseudoalbidus, was present on rachis and infected hosts only in Northeastern France and showed strong pathogenicity towards ash seedlings in inoculation tests. By contrast, the second type, which corresponds to H. albidus, was present throughout Northern France and showed no pathogenicity towards ash seedlings. Our study confirms the results of Queloz et al. (2010) who presented molecular evidences for the existence of two cryptic species, H. albidus and H. pseudoalbidus. The results strongly suggest that Chalara fraxinea/H. pseudoalbidus is a recent invader in France.     

Replication of a 1970s Study on Domestic Sheep Losses to Predators on Utah's Summer Rangelands

Lamb losses to predation have historically ranged from 4% to 8% in the western United States but most data are over 30 yr old. We repeated a sheep depredation study conducted from 1972 through 1975 on Cedar Mountain, Utah, to determine how predation rates have changed in the last three decades. Pastures and herd sizes were similar (1 730 lambs) between our study (2006 and 2007) and the prior one. Additionally, 40% of the ranchers in our study also participated in the prior study. During 2006 and 2007, 5.8% of all lambs on Cedar Mountain were lost to all causes compared to 9.5% during the 1970s. Predators were responsible for 87% of all verified lamb losses during our study versus 83% during the 1970s. We estimated that 4.9% of all lambs on Cedar Mountain were killed by predators during our study compared to 7.9% during the 1970s. During our study, coyotes (Canis latrans Say) were responsible for 67% of the depredated lambs, cougars (Felis concolor Linnaeus) for 31%, and black bears (Ursus americanus Pallas) for 2%. During the 1970s, coyotes killed 98% of all depredated lambs, cougars killed 2%, and bears killed 0%. In addition to the increase in cougar kills, the other change on Cedar Mountain since the 1970s is that California condors (Gymnogyps californianus Shaw) have begun scavenging lamb carcasses. Our results indicate that increasing populations of cougars, black bears, and condors have complicated the task of protecting lambs from predators.     

Epidemiological and microbiological study of an outbreak of infectious keratoconjunctivitis in sheep

After several thousand sheep had been imported from Australia and New Zealand to Croatia during 1995, many native sheep that had been in contact with the imported animals acquired a severe ocular disease closely resembling infectious keratoconjunctivitis. In affected flocks glucose-fermenting mycoplasma were isolated from 48 per cent of conjunctival swabs and Branhamella ovis from 58 per cent. Twelve of 42 culturally and biochemically identical isolates were identified as Mycoplasma conjunctivae by polymerase chain reaction. From the conjunctivae of two animals M conjunctivae and M arginini were isolated in mixed culture. For many reasons most farmers removed the imported animals from their flocks and only sporadic cases of the disease were recognised in 1996. At the end of 1997, six flocks which were clinically free of the disease but had been affected during 1995, and five flocks with no history of the severe ocular disease were examined clinically and microbiologically, and were found to be free of M conjunctivae infection. At the time, B ovis was cultured almost exclusively from sheep originating from flocks which had been affected during 1995 and/or 1996. It was usually isolated in pure culture or as the predominant bacterial species, and was often accompanied by mild conjunctivitis. There were no microbiologically confirmed new cases of infectious keratoconjunctivitis during 1998 and 1999.     

Magnesium pemoline: effect on avoidance conditioning in rats

Rats administered 20 milligrams of magnesium pemoline per kilo gram of body weight learned to avoid shock in a jump-out apparatus in fewer trials than did controls. However, the results suggested that the principal effect of the drug was to facilitate the avoidance behavior of those animals that tended to "freeze" in response to electric grid shock. No differences in retention were observed between experimental and control animals that had achieved equal levels of learnine.     

The Emperor Seamounts: southward motion of the Hawaiian hotspot plume in Earth's mantle

The Hawaiian-Emperor hotspot track has a prominent bend, which has served as the basis for the theory that the Hawaiian hotspot, fixed in the deep mantle, traced a change in plate motion. However, paleomagnetic and radiometric age data from samples recovered by ocean drilling define an age-progressive paleolatitude history, indicating that the Emperor Seamount trend was principally formed by the rapid motion (over 40 millimeters per year) of the Hawaiian hotspot plume during Late Cretaceous to early-Tertiary times (81 to 47 million years ago). Evidence for motion of the Hawaiian plume affects models of mantle convection and plate tectonics, changing our understanding of terrestrial dynamics.     

Detection of the genome of bovine viral diarrhea virus (BVDV) using the polymerase chain reaction after reverse transcription (RT-PCR): comparison of methods for the isolation of ribonucleic acid (RNA) from clinical samples

The RT-PCR is an in vitro technique that is increasingly being used for diagnosis of viral animal pathogens. Due to its high sensitivity it is considered as an alternative to current standard methods for detecting BVDV especially in pooled samples, e.g. from bulk tank milk. A prerequisite for the performance of RT-PCR is an efficient and simple method for sample preparation. The aim of this work was to compare the efficiency of three commercially available kits for RNA extraction, and their suitability for sample preparation for the detection of the BVDV genome by RT-PCR in blood, milk and tissue samples. The kits were based on different methods for extraction of RNA and differed in costs, labour and time consumption. The most sensitive RT-PCRs (exception: heparinised blood) were obtained when sample preparation was performed by acidic guanidinium-isothiocyanate-phenol-chloroform extraction with the Trizol (Gibco) reagent. Using a kit based on the binding of RNA to silica membrane in a spin column, positive results in RT-PCR were obtained from all samples, but with lower sensitivity. The advantage of the column-based kits is that they are less time-consuming, easier to handle and suitable for automatisation of sample preparation. A kit using salt precipitation of the desoxribose nucleic acid (DNA) and proteins was unsuitable for the isolation of viral RNA from the samples.     

PCR specific for Actinobacillus pleuropneumoniae serotype 3

Serotypes 3 and 8 of Actinobacillus pleuropneumoniae, the aetiological agent of porcine pleuropneumonia, have been reported to predominate in the UK. Direct serotyping of isolates of the organism is typically determined by the immunological reactivity of rabbit serum to its surface polysaccharides, but the method has limitations, for example, cross-reactions between serotypes 3, 6 and 8. This study describes the development of a serotype 3-specific pcr, based on the capsule locus, which can be used in a multiplex format with the organism's specific gene apxIV. The pcr test was evaluated on 266 strains of A pleuropneumoniae and 121 strains of other organisms, including all the major respiratory bacterial pathogens of pigs. The test was highly specific and sensitive and should be useful for differentiating strains of serotypes 3, 6 and 8, and in seroprevalence and epidemiological surveys in regions where serotype 3 is prevalent, such as the UK.