Limited gene flow among brown bear populations in far Northern Europe? Genetic analysis of the east-west border population in the Pasvik Valley.

Noninvasively collected genetic data can be used to analyse large-scale connectivity patterns among populations of large predators without disturbing them, which may contribute to unravel the species' roles in natural ecosystems and their requirements for long-term survival. The demographic history of brown bears (Ursus arctos) in Northern Europe indicates several extinction and recolonization events, but little is known about present gene flow between populations of the east and west. We used 12 validated microsatellite markers to analyse 1580 hair and faecal samples collected during six consecutive years (2005-2010) in the Pasvik Valley at 70°N on the border of Norway, Finland and Russia. Our results showed an overall high correlation between the annual estimates of population size (N(c) ), density (D), effective size (N(e) ) and N(e) /N(c) ratio. Furthermore, we observed a genetic heterogeneity of ∼0.8 and high N(e) /N(c) ratios of ∼0.6, which suggests gene flow from the east. Thus, we expanded the population genetic study to include Karelia (Russia, Finland), Västerbotten (Sweden) and Troms (Norway) (477 individuals in total) and detected four distinct genetic clusters with low migration rates among the regions. More specifically, we found that differentiation was relatively low from the Pasvik Valley towards the south and east, whereas, in contrast, moderately high pairwise F(ST) values (0.91-0.12) were detected between the east and the west. Our results indicate ongoing limits to gene flow towards the west, and the existence of barriers to migration between eastern and western brown bear populations in Northern Europe.

Genome sequence of the Arctic methanotroph Methylobacter tundripaludum SV96.

Methylobacter tundripaludum SV96(T) (ATCC BAA-1195) is a psychrotolerant aerobic methane-oxidizing gammaproteobacterium (Methylococcales, Methylococcaceae) living in High Arctic wetland soil. The strain was isolated from soil harvested in July 1996 close to the settlement Ny-Ålesund, Svalbard, Norway (78°56'N, 11°53'E), and described as a novel species in 2006. The genome includes pmo and pxm operons encoding copper membrane monooxygenases (Cu-MMOs), genes required for nitrogen fixation, and the nirS gene implicated in dissimilatory nitrite reduction to NO but no identifiable inventory for further processing of nitrogen oxides. These genome data provide the basis to investigate M. tundripaludum SV96, identified as a major player in the biogeochemistry of Arctic environments.

Archaeal diversity and community structure in a Swedish barley field: Specificity of the EK510R/(EURY498) 16S rDNA primer.

The aim of this study was to analyze a total euryarchaeal community at DNA and RNA levels in a Swedish barley field with relation to soil depth (0-10 and 20-30 cm layers), soil fraction (bulk soil and rhizosphere) and time (August and November sample collection). Amplification of 16S rRNA gene using the archaeal universal A2F and Euryarchaea specific EK510R/(EURY498) primer pair, combined with denaturing gradient gel electrophoresis (DGGE), revealed distinct differences between rDNA and rRNA DGGE profiles. The soil depth, time, or rhizosphere effects did not significantly influence Archaeal community structure. Surprisingly, sequence analysis of DGGE-derived amplicons revealed the presence of Euryarchaea as well as uncultured soil Crenarchaea affiliated with group 1. In agreement, sequence comparison analyses showed that the majority of uncultured Crenarchaea group 1 had almost 100% sequence complementarity to the 3' end of the EK510R/(EURY498) primer. Therefore, we propose that EK510R/(EURY498R) is a universal archaeal primer rather than a Euryarchaea specific SSUrRNA primer. Hence, considerable care should be taken during application of this primer in studies of euryarchaeal biodiversity in soil environments.

Isolation of methane oxidising bacteria from soil by use of a soil substrate membrane system.

Abstract A new method for isolation of methane oxidising bacteria (methanotrophs) is presented. Soil samples from a wetland area and a landfill were plated on polycarbonate membranes, which were incubated in a methane-air atmosphere using a non-sterile soil suspension as the medium. The membrane acted as a permeable growth support. The membrane method resulted in selective growth conditions, which allowed isolation of methane oxidising bacteria. The method resulted in isolation of both type I and type II methanotrophs from natural wetland and landfill soils. The isolates obtained from the landfill were dominated by type II methanotrophs and included several isolates carrying the gene for soluble methane monooxygenase (sMMO). Repetitive element sequence-based PCR fingerprinting documented genotypic diversity at the strain level. The presented method is a promising tool for easy and rapid isolation of different indigenous methanotrophs from an environment of interest.

Methylobacter tundripaludum sp. nov., a methane-oxidizing bacterium from Arctic wetland soil on the Svalbard islands, Norway (78 degrees N).

A Gram-negative, rod-shaped, non-motile, non-spore forming bacterium (SV96T) was isolated from wetland soil near Ny-Alesund, Svalbard. On the basis of 16S rRNA gene sequence similarity, strain SV96T was shown to belong to the Gammaproteobacteria, related to Methylobacter psychrophilus Z-0021T (99.1 %), Methylobacter luteus ATCC 49878T (97.3 %), Methylobacter marinus A45T (97.0 %) and Methylobacter whittenburyi ATCC 51738T (95.8 %); the closest related species within the genus Methylomicrobium with a validly published name was Methylomicrobium album ATCC 33003T (95.0 %). Chemotaxonomic data (including the major fatty acids: 16 : 1omega8, 16 : 1omega7 and 16 : 1omega5t) supported the affiliation of strain SV96T to the genus Methylobacter. The results of DNA-DNA hybridization, physiological and biochemical tests allowed genotypic and phenotypic differentiation of strain SV96T from the four Methylobacter species mentioned above. Strain SV96T therefore represents a novel species, for which the name Methylobacter tundripaludum sp. nov. is proposed (type strain SV96T = DSM 17260T = ATCC BAA-1195T).

Methylocystis rosea sp. nov., a novel methanotrophic bacterium from Arctic wetland soil, Svalbard, Norway (78 degrees N).

A Gram-negative, rod-shaped, non-motile, non-spore-forming, pink-pigmented bacterium, SV97T, was isolated from a wetland soil near Ny-Alesund, Svalbard Islands, Norway (78 degrees N). On the basis of 16S rRNA gene sequence similarity, strain SV97T was shown to belong to the Alphaproteobacteria and was highly related to a number of non-characterized Methylocystis strains with GenBank accession nos AJ458507 and AJ458502 (100 %) and AF177299, AJ458510, AJ458467, AJ458471, AJ431384, AJ458475, AJ458484, AJ458501 and AJ458466 (99 %). The most closely related type strains were Methylocystis parvus OBBP(T) (97.2 %) and Methylocystis echinoides IMET 10491T (97%). The closest related recognized species within the genus Methylosinus was Methylosinus sporium NCIMB 11126T (96.0% similarity). Chemotaxonomic and phenotypic data (C(18:1)omega8 as the major fatty acid, non-motile, no rosette formation) supported the affiliation of strain SV97T to the genus Methylocystis. The results of DNA-DNA hybridization and physiological and biochemical tests allowed genotypic and phenotypic differentiation of strain SV97(T) from the two recognized Methylocystis species. Strain SV97T therefore represents a novel species, for which the name Methylocystis rosea sp. nov. is proposed, with the type strain SV97T (= DSM 17261T = ATCC BAA-1196T).

Methanotrophic diversity in high arctic wetlands on the islands of Svalbard (Norway)--denaturing gradient gel electrophoresis analysis of soil DNA and enrichment cultures.

The methanotrophic community in arctic soil from the islands of Svalbard, Norway (78 degrees N) was analysed by combining group-specific PCR with PCR of the highly variable V3 region of the 16S rRNA gene and then by denaturing gradient gel electrophoresis (DGGE). Selected bands were sequenced for identification. The analyses were performed with DNA extracted directly from soil and from enrichment cultures at 10 and 20 degrees C. The two genera Methylobacter and Methylosinus were found in all localities studied. The DGGE band patterns were simple, and DNA fragments with single base differences were separated. The arctic tundra is a potential source of extensive methane emission due to climatic warming because of its large reservoirs of stored organic carbon. Higher temperatures due to climatic warming can cause increased methane production, and the abundance and activity of methane-oxidizing bacteria in the arctic soil may be important regulators for methane emission to the atmosphere.