Phylogenetic analyses of nitrogen-fixing cyanobacteria from the Baltic Sea reveal sequence anomalies in the phycocyanin operon.
(17/93)
The examination of molecular phylogenies of cyanobacteria and other micro-organisms is increasing dramatically. The use of a single locus in these studies leaves the resulting phylogenies unconfirmed. In this study, the partial sequences of two loci containing segments of protein-encoding genes, the hetR and the phycocyanin locus (PC-IGS), were examined. Laboratory strains and natural populations of the heterocyst-forming cyanobacteria Anabaena, Aphanizomenon and Nodularia from the Baltic Sea were used, in total 41 sequences were determined and their phylogenies were analysed with maximum-likelihood methods. The hetR phylogenies suggested that the planktonic Aphanizomenon and Nodularia each comprise one species, while there were numerous Anabaena species present in the Baltic Sea. In the case of Nodularia, the PC-IGS phylogenies were incongruent with this and suggested that several lineages of Nodularia plankton species existed. In the hetR phylogeny, the floating and nodularin-producing strains of Nodularia were grouped together. For both the hetR and PC-IGS loci of cultured species of Nodularia their molecular phylogeny did not correspond well with the affiliation suggested by morphology. In sequences derived from species of Anabaena and Aphanizomenon the PC-IGS and hetR phylogenies were congruent, suggesting that Aphanizomenon sp. from the Baltic Sea is genetically distinct from both Aphanizomenon flos-aquae from lakes and Aphanizomenon sp. TR183 from the Baltic Sea. In both Nodularia and Anabaena/Aphanizomenon, the PC-IGS sequences showed a significant degree of either recombination events or selection, while none was detected within the hetR sequences. This is the first study comprising the phylogenies of multiple loci from all heterocystous cyanobacteria from the Baltic Sea and shows that earlier results using the PC-IGS locus should be interpreted cautiously in the absence of a confirmation using a second locus. (+info)
Rheinheimera baltica gen. nov., sp. nov., a blue-coloured bacterium isolated from the central Baltic Sea.
(18/93)
A set of taxonomically unique, blue-coloured bacterial isolates are described on the basis of physiological and biochemical characterization, fatty acid profiling and analyses of 16S rDNA sequences. The flagellated, non-fermentative strains were isolated in 1986, 1987 and 1998 from different layers of the water column of the central Baltic Sea. According to 16S rDNA sequences, all strains are very closely related to each other and to strains from several other marine environments, including the deep sea. Thus, the described species seems to be widespread in marine habitats. According to DNA-DNA hybridization, the strains described can be considered to belong to the same species. The bacteria grew at temperatures from 4 to 30 degrees C, with an optimum around 20-25 degrees C. Growth was observed at salinities from 0 to 30, with an optimum between 10 and 30 and no growth at high salinities. The dominant fatty acids were 16:1omega7c, 16:0 and 18:1omega7c. The G+C content of the DNA ranged from 47.8 to 48.9 mol%. Phylogenetic analyses of the 16S rDNA sequences revealed a clear affiliation with members of the gamma-Proteobacteria. The closest relationship was seen with Alishewanella fetalis but, in terms of physiology, colour and fatty acids, the bacteria described are rather distant from A. fetalis. To honour the marine microbiologist Gerhard Rheinheimer, the name Rheinheimera baltica gen. nov., sp. nov., is suggested for the Baltic isolates, with the type strain OSBAC1T (= DSM 14885T = LMG 21511T). (+info)
Shewanella denitrificans sp. nov., a vigorously denitrifying bacterium isolated from the oxic-anoxic interface of the Gotland Deep in the central Baltic Sea.
(19/93)
Three strains of denitrifying estuarine bacteria, OS217(T), 05220 and OS226, were characterized for their physiological and biochemical features, fatty acid profiles and their phylogenetic position based on 16S rDNA sequences. The strains were isolated from the oxic-anoxic interface of an anoxic basin of the central Baltic Sea. Phylogenetic analyses of the 16S rDNA sequences revealed a clear affiliation with members of the genus Shewanella of the gamma-Proteobacteria. The closest sequence similarity was seen with Shewanella baltica, Shewanella putrefaciens and Shewanella frigidimarina (95-96%). The dominant fatty acids were 16:1omega7c, 15:0 iso, 16:0 and 13:0 iso. The G+C content of the DNA ranged from 46.8 to 48.1 mol%. The strains were unpigmented, polarly flagellated, mesophilic, facultatively anaerobic and able to use nitrate, nitrite and sulphite as electron acceptors. Growth was observed at salinities from 0 to 6%, with an optimum between 1 and 3%. According to their morphology, physiology, fatty acid composition and 16S rRNA sequences, the described bacteria fitted well into the genus Shewanella, but could be easily distinguished from the Shewanella species described to date. Because of their capacity for vigorous denitrification, the name Shewanella denitrificans sp. nov. is suggested for the Baltic isolates, for which the type strain is OS217(T) (= DSM 15013(T) = LMG 21692(T)). (+info)
Idiomarina baltica sp. nov., a marine bacterium with a high optimum growth temperature isolated from surface water of the central Baltic Sea.
(20/93)
Two bacterial strains isolated from the Baltic Sea, OS145T and OS146, were characterized on the basis of their physiological and biochemical features, their fatty acid profiles and their phylogenetic position based on 16S rDNA sequence analyses. The strains were isolated from the upperoxic water column of the central Baltic Sea. Phylogenetic analyses of the 16S rDNA gene sequences revealed a clear affiliation of the novel strains with members of the genus Idiomarina, of the Gammaproteobacteria. Closest sequence similarity was seen with Idiomarina abyssalis and Idiomarina zobellii (95-96%). The mean G + C content of the DNA of strains OS145T and OS146 was 49.7 mol%. Both strains were non-pigmented, Gram-negative, polarly flagellated organisms that were strictly aerobic. Growth of the strains was observed at salinities ranging from 0.8 to 10% NaCl. Temperature range for growth was rather broad and high for marine bacteria: both strains grew between 8 and 46 degrees C, showed good growth between 20 and 44 degrees C, and had an optimum between 30 and 40 degrees C. The fatty acids of the two strains were dominated by iso-branched fatty acids (54-80%), with a high abundance of C15:0 iso (36%), C16:1 omega7c, C17:o iso and C17:1 iso omega9c. Growth temperature (8-40 degrees C) influenced the fatty acid composition of the strains in a way that the content of iso-branching fatty acids increased with increasing temperatures, while the mono-unsaturated fattyacids increased with decreasing temperatures. Salinity (1.7-10% NaCl) had only a minor effect on the fatty acid composition. According to their morphology, physiology, fatty acid composition and 16S rDNA sequences, strains OS145T and OS146 fitted well into the genus Idiomarina, but could be easily distinguished from the recognized species of the genus. Because of their unique nature, it is proposed that the strains isolated from the Baltic Sea represent a novel species, for which the name Idiomarina baltica (type strain OS145T =DSM 15154T =LMG 21691T) is proposed. (+info)
The evolving pattern of avoidable mortality in Russia.
(21/93)
BACKGROUND: Life expectancy at birth in Russia is over 12 years less than in western Europe. This study explores the possible role of medical care in explaining this gap by examining the evolving pattern of mortality amenable to timely and effective medical care in Russia compared with Estonia, Latvia, and Lithuania, and the UK. METHODS: Analysis of standardized death rates from causes amenable to health care (treatable) or inter-sectoral health policies (preventable) in all regions and decomposition of differences in life expectancy between Russia and the UK by age, sex, and cause of death for the period 1965-1999/2000. RESULTS: Death rates from treatable causes remained stable between the mid-1960s and mid-1980s in Russia and the Baltic republics while steadily falling in the UK to less than half the rate in Russia. In the 1990s, rates increased in the former Soviet republics, reaching a peak in 1994 but reversing again in Russia in 1998. Deaths from causes amenable to inter-sectoral health interventions were higher in the UK in 1965 than in the Soviet Union but subsequently fell steadily while they increased in the East. Between 1965 and 1999, the male life expectancy gap between Russia and the UK rose from 3.6 to 15.1 years (women: 1.6 and 7.4 years). Treatable causes became an increasingly important contributor to this gap, accounting for almost 3 years by the end of the 1990s in men and 2 years in women. In Russia, elimination of treatable causes of death would have increased life expectancy by 2.9 years in men in 1995/99 compared with 1.2 years in the UK (women: 3.3 and 1.8 years), suggesting that, were the outcomes of health care achieved in the UK to be obtained in Russia, life expectancy for men might improve by about 1.7 years and for women by about 1.5 years. CONCLUSIONS: Our findings suggest that the Soviet health care system has failed to match the achievements of the West over the past three decades, highlighting the need to establish a system that provides effective and equitable care for the Russian population. (+info)
Development and application of a real-time PCR approach for quantification of uncultured bacteria in the central Baltic Sea.
(22/93)
We have developed a highly sensitive approach to assess the abundance of uncultured bacteria in water samples from the central Baltic Sea by using a noncultured member of the "Epsilonproteobacteria" related to Thiomicrospira denitrificans as an example. Environmental seawater samples and samples enriched for the target taxon provided a unique opportunity to test the approach over a broad range of abundances. The approach is based on a combination of taxon- and domain-specific real-time PCR measurements determining the relative T. denitrificans-like 16S rRNA gene and 16S rRNA abundances, as well as the determination of total cell counts and environmental RNA content. It allowed quantification of T. denitrificans-like 16S rRNA molecules or 16S rRNA genes as well as calculation of the number of ribosomes per T. denitrificans-like cell. Every real-time measurement and its specific primer system were calibrated using environmental nucleic acids obtained from the original habitat for external standardization. These standards, as well as the respective samples to be measured, were prepared from the same DNA or RNA extract. Enrichment samples could be analyzed directly, whereas environmental templates had to be preamplified with general bacterial primers before quantification. Preamplification increased the sensitivity of the assay by more than 4 orders of magnitude. Quantification of enrichments with or without a preamplification step yielded comparable results. T. denitrificans-like 16S rRNA molecules ranged from 7.1 x 10(3) to 4.4 x 10(9) copies ml(-1) or 0.002 to 49.7% relative abundance. T. denitrificans-like 16S rRNA genes ranged from 9.0 x 10(1) to 2.2 x10(6) copies ml(-1) or 0.01 to 49.7% relative abundance. Detection limits of this real-time-PCR approach were 20 16S rRNA molecules or 0.2 16S rRNA gene ml(-1). The number of ribosomes per T. denitrificans-like cell was estimated to range from 20 to 200 in seawater and reached up to 2,000 in the enrichments. The results indicate that our real-time PCR approach can be used to determine cellular and relative abundances of uncultured marine bacterial taxa and to provide information about their levels of activity in their natural environment. (+info)
Unfolding of population structure in Baltic sheep breeds using microsatellite analysis.
(23/93)
Studies of domestic animals are performed on breeds, but a breed does not necessarily equate to a genetically defined population. The division of sheep from three native and four modern Baltic sheep breeds was studied using 21 microsatellite loci and applying a Bayesian clustering method. A traditional breed-wise approach was compared to that relying on the pattern of molecular diversity. In this study, a breed was found to be inconsistent with a distinct genetic population for three reasons: (i) a lack of differentiation between modern Baltic breeds, since the majority of the studied sheep formed a single population; (ii) the presence of individuals of foreign ancestry within the breed; and (iii) an undefined local Saaremaa sheep was referred to as a breed, but was shown to consist of separate populations. In the breed-wise approach, only the clearly distinct Ruhnu sheep demonstrated low within-breed variation, although the newly identified Saaremaa populations also have low variability. Providing adequate management recommendations for the Saaremaa sheep is not possible without further studies, but the potential harmful effects of inbreeding in the Ruhnu sheep could be reduced through the use of two genetically related Saaremaa populations. In other breeds, excessive crossing appears to be a larger concern than inbreeding. Assigning individuals into populations based on the pattern of genetic diversity offers potentially unbiased means of elucidating the genetic population structure of species. Combining these genetic populations with phenotypic and aetiological data will enable formulation of the most informed recommendations for gene resource management. (+info)
Extensive immigration from compensatory hatchery releases into wild Atlantic salmon population in the Baltic sea: spatio-temporal analysis over 18 years.
(24/93)
Genetic homogenization has been recognized as a serious threat in an increasing number of species, including many salmonid fishes. We assessed the rate and impact of immigration from the main hatchery stocks of Atlantic salmon in the Gulf of Bothnia into one of the largest wild salmon populations in the Baltic Sea, the River Vindelalven, within a temporal framework of 18 years (from 1985-2003). We provide genetic evidence based on mtDNA and microsatellite markers, using mixed-stock analysis, that a large proportion (66%) of fin-damaged spawners (n=181) caught in the Ume/Vindelalven during 1997-2003 originated from the hatcheries in the Rivers Angermanalven, Lulealven and Ljusnan. The maximum-likelihood estimate of immigration rate from these hatcheries into the wild Vindelalven population was 0.068 (95% CI 0.021-0.128) over the studied time period (1985-2003) and reached up to a quarter (m=0.249, 95% CI 0.106-0.419) of the total population during 1993-2000. This resulted in significant (P<0.01) genetic homogenization trend between the wild Vindelalven population and hatchery stocks of the Angermanalven and Lulealven. Our results demonstrate extensive straying from geographically distant hatchery releases into wild salmon population and emphasize the genetic risks associated with current large-scale stocking practices in the Baltic Sea. (+info)