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European Strains (european + strain)
Selected AbstractsTo sample or eradicate?JOURNAL OF APPLIED ECOLOGY, Issue 4 2008A cost minimization model for monitoring, managing an invasive species Summary 1Considerable effort is expended by national and local governments to exclude alien species via detection and eradication of invading populations, but these efforts are not necessarily designed in the most economically or biologically efficient manner. 2Using the invasion of the European strain of the gypsy moth Lymantria dispar into the USA as a case study, we develop an analytical model to determine the optimal trap density for detecting isolated infestations. Most models focus on monitoring or eradication costs only; our model considers the costs of both detection and eradication when determining the best monitoring strategy. 3The model assumes that all isolated populations must be located and eradicated by the conclusion of a programme. For programmes lasting longer than 1 year, it is more worthwhile to proactively monitor and manage rather than to wait until the programme is over. 4For a management programme of a given length, optimal trap density is most influenced by the growth rate of the infestation. Optimal trap densities are lowest for infestations with very low growth rates (because they remain small and therefore are less expensive to eradicate) or very high growth rates (because they are easier to detect), and highest for infestations with moderate growth rates (because they are neither inexpensive to eradicate nor easy to detect). 5Our model is useful in setting a baseline level of monitoring for isolated incidents of gypsy moth invasion. Analysis of data in two US states show that actual trap densities are far higher than the optimal densities from the model. The difference suggests risk aversion may play a role in real systems. 6Synthesis and applications. Our model suggests that we can improve the efficiency of detection and eradication programmes for isolated infestations by optimizing detection effort relative to infestation growth rates and management programme duration. It also clearly demonstrates the importance of balancing the costs and benefits of both detection and eradication when developing invasive species monitoring programmes. [source] Interfertility between North American and European strains of Phlebiopsis giganteaFOREST PATHOLOGY, Issue 3 2005R. Grillo Summary Thirteen homokaryotic strains of Phlebiopsis gigantea from Canada, six strains from the US and 10 strains from Europe were paired in all possible combinations in order to determine the degree of interfertility between them. The diagnosis of interfertility was based on the production of heterokaryotic fruit bodies in the pairings. Among the resulting 406 pairings, 253 (62%) fruited. Within the strains originating from Canada, USA and Europe, 64, 80 and 64% of the pairings fruited, respectively. The fruiting frequency in pairings between the Canadian and US strains was 65%, between the Canadian and European strains 55%, and between the US and European strains 67%. True hybridization between the European and North American P. gigantea was shown by analysing the single-spore progeny using DNA fingerprinting. In spite of the relatively low interfertility in pairings within and between continents, no clear indication of the existence of intersterility groups was found. The low interfertility is probably due to the ageing of the pure cultures and to deficient fruiting ability of certain heterokaryons on agar medium. The results strongly suggest that although the North American and European strains of P. gigantea show some differentiation they can be regarded as belonging to the same biological species. Résumé Treize souches homocaryotiques de Phlebiopsis gigantea du Canada, 6 des Etats-Unis et 10 d'Europe ont été confrontées par paires selon toutes les combinaisons possibles pour déterminer leur degré d'interfertilité. Le diagnostic d'interfertilité est basé sur la production de fructifications hétérocaryotiques dans les confrontations. Parmi les 406 paires, 253 (62%) ont fructifié. Ce pourcentage est de 64, 80 et 64% respectivement pour les souches du Canada, des Etats-Unis ou d'Europe entre elles. La fréquence de fructification pour les confrontations entre souches du Canada et des Etats-Unis est de 65%, entre souches européennes et canadiennes de 55% et entre souches des USA et d'Europe de 67%. La réalité de l'hybridation entre souches européennes et nord américaines a été démontrée par analyse de la descendance de spores par empreinte génétique. Malgré la relativement faible interfertilité dans les confrontations intra ou inter continents, l'existence de groupes d'interstérilité n'a pu être montrée. La faible interfertilité est probablement due au vieillissement des cultures pures et à une faible capacitéà fructifier sur milieu gélosé de certains hétérocaryons. Les résultats suggèrent fortement que malgré une certaine différenciation entre souches nord américaines et européennes de P. gigantea, celles-ci peuvent être considérées comme appartenant à la même espèce. Zusammenfassung Zur Bestimmung der Interfertilität wurden 13 homokaryotische Isolate von Phlebiopsis gigantea aus Kanada, 6 aus den USA und 10 aus Europa in allen möglichen Kombinationen miteinander gekreuzt. Der Erfolg der Kreuzungen wurde anhand der Bildung von heterokaryotischen Fruchtkörpern beurteilt. Bei insgesamt 406 Kreuzungen wurden in 253 Fällen (62%) Fruchtkörper gebildet. Unter den Stämmen aus Kanada, den USA und Europa kam es in 64, 80 und 64% der Fälle zur Fruchtkörperbildung. Bei Paarungen zwischen Isolaten aus Kanada und den USA fruktifizierten 65%, bei Paarungen zwischen Isolaten aus Kanada und Europa waren dies 55%, Paarungen zwischen Isolaten aus den USA und Europa fruktifizierten zu 67%. Die echte Hybridisierung zwischen europäischen und nordamerikanischen Isolaten von P. gigantea wurde durch Analysen der Einzelsporisolate aus den Fruchtkörpern durch DNA-Fingerprinting nachgewiesen. Trotz der relativ geringen Interfertilität innerhalb und zwischen den Kontinenten wurden keine klaren Hinweise auf die Existenz von Intersterilitätsgruppen gefunden. Die geringe Interfertilität ist möglicherweise durch eine Degeneration der Kulturen in vitro und durch die fehlende Fähigkeit mancher Heterokaryen zur Fruchtkörperbildung auf Agarmedien erklärbar. Die Ergebnisse zeigen, dass Isolate von P. gigantea aus Nordamerika und Europa trotz einer gewissen geographischen Differenzierung zu einer einzigen biologischen Art gehören. [source] Characterization of tick-borne encephalitis virus from latvia: Evidence for co-circulation of three distinct subtypesJOURNAL OF MEDICAL VIROLOGY, Issue 4 2001Åke Lundkvist Abstract Viruses of the tick-borne encephalitis (TBE) antigenic complex within the family Flaviviridae cause a variety of diseases, including uncomplicated febrile illness, meningoencephalitis, and hemorrhagic fever. Different domesticated animals or wildlife species often act as reservoir hosts and ixodid ticks serve as vectors. Although TBE is a serious problem in Latvia, the knowledge concerning TBE virus (TBEV) strains circulating in the country is most limited. Only two strains (Latvia-1-96 isolated from a TBE patient, and RK1424 originating from an Ixodes persulcatus tick), which belonged to the Siberian and the Far Eastern subtypes of TBEV, respectively, have previously been characterized. In the present study, we concentrated on the western and central regions of Latvia, with predominantly Ixodes ricinus ticks. Five virus strains were isolated from serum samples of patients with clinical symptoms of an acute TBE infection. Nucleotide sequences encoding the envelope (E) protein of TBEV, which were recovered from the five TBEV isolates, showed the highest level of identity to the corresponding sequences of the prototype strain Neudoerfl and other European strains of the Western TBEV subtype characterized previously. Accordingly, phylogenetic analysis placed the new Latvian isolates within the Western genetic lineage of TBEV. Taken together with earlier observations, the results proved that all three TBEV subtypes are co-circulating in Latvia and indicated that the genetic diversity of TBEV within certain geographical areas is much more complex than previously believed. J. Med. Virol. 65:730,735, 2001. © 2001 Wiley-Liss, Inc. [source] Phylogeography of the invasive cyanobacterium Cylindrospermopsis raciborskiiMOLECULAR ECOLOGY, Issue 1 2003B. A. Neilan Abstract Cylindrospermopsis raciborskii is a planktonic freshwater cyanobacterium that has become increasingly prevalent in tropical and temperate water bodies world-wide. This species is of concern from a water-quality perspective because of its known ability to produce toxins that can affect the health of humans and other animals. This study investigates genetic vari-ation between strains of C. raciborskii isolated from freshwater rivers and reservoirs in Australia, Brazil, Germany, Hungary, Portugal and the USA. Strains were first characterized by analysis of their 16S rRNA gene nucleotide sequences and were found to have a sequence divergence of 99.1%. A phylogenetic tree, constructed using the 16S rRNA gene sequences showed that strains grouped into Australian, European and North/South American phylotypes. To investigate further the observed separation of strains into geographically distinct groups, we applied a cyanobacterium-specific short tandem repeat sequence technique, HIP1. An electrophoretic comparison of the HIP1 polymerase chain reaction products showed clear distinctions between the C. raciborskii strains. A phylogenetic tree, based on the repeat element banding patterns, also revealed three distinct groups of C. raciborskii strains. The first group consisted of strains from the USA and Brazil; the second comprised European strains from Germany, Hungary and Portugal; and the third were strains from Australia. In general, between-country variation was greater than within-country variation, indicating that this fingerprinting technique can successfully distinguish C. raciborskii strains taken from different global locations. The relationship between toxicity and the observed HIP1 polymerase chain reaction fingerprint profiles was less clear, although it is interesting to note that of the strains analysed in this study, only Australian strains are known to produce cylindrospermopsin and only Brazilian strains have been reported to produce paralytic shellfish poisoning toxins. [source] | ||||||||||