Seasonality in bacterial diversity in north-west Mediterranean coastal waters: assessment through clone libraries, fingerprinting and FISH

We combined denaturing gradient gel electrophoresis (DGGE), catalysed reporter deposition-FISH (CARD-FISH) and clone libraries to investigate the seasonality of the bacterial assemblage composition in north-west Mediterranean coastal waters. DGGE analysis indicated that bacterial diversity changed gradually throughout the year, although with a clear distinction of the summer period. Alphaproteobacteria were the dominant group on an annual basis [29% of the DAPI (4′,6-diamidino-2-phenylindole) counts by CARD-FISH, and 70% of the bacterial clones]. The SAR11 clade was most abundant during spring and summer (>20% of DAPI counts), while the Roseobacter clade was abundant primarily in winter and spring (up to 7% of DAPI counts). The phylum Bacteroidetes constituted the second most important group and was quantitatively uniform throughout the year (average 11% of the DAPI counts). Gammaproteobacteria showed a peak during summer (8% of DAPI counts), when most of them belonged to the NOR5 cluster. Clone libraries and CARD-FISH showed reasonable agreement in the quantitative proportions of Bacteroidetes and Gammaproteobacteria, but Alphaproteobacteria were overrepresented in clone libraries. Sequencing of the most predominant DGGE bands failed to detect the SAR11 group despite their high abundance. The combination of the three molecular approaches allowed a comprehensive assessment of seasonal changes in bacterial diversit

Seasonality in bacterial diversity in north-west Mediterranean coastal waters: assessment through clone libraries, fingerprinting and FISH

16 pages, 8 figuresWe combined denaturing gradient gel electrophoresis (DGGE), catalysed reporter deposition-FISH (CARD-FISH) and clone libraries to investigate the seasonality of the bacterial assemblage composition in north-west Mediterranean coastal waters. DGGE analysis indicated that bacterial diversity changed gradually throughout the year, although with a clear distinction of the summer period. Alphaproteobacteria were the dominant group on an annual basis [29% of the DAPI (4',6-diamidino-2-phenylindole) counts by CARD-FISH, and 70% of the bacterial clones]. The SAR11 clade was most abundant during spring and summer (>20% of DAPI counts), while the Roseobacter clade was abundant primarily in winter and spring (up to 7% of DAPI counts). The phylum Bacteroidetes constituted the second most important group and was quantitatively uniform throughout the year (average 11% of the DAPI counts). Gammaproteobacteria showed a peak during summer (8% of DAPI counts), when most of them belonged to the NOR5 cluster. Clone libraries and CARD-FISH showed reasonable agreement in the quantitative proportions of Bacteroidetes and Gammaproteobacteria, but Alphaproteobacteria were overrepresented in clone libraries. Sequencing of the most predominant DGGE bands failed to detect the SAR11 group despite their high abundance. The combination of the three molecular approaches allowed a comprehensive assessment of seasonal changes in bacterial diversityThis work was supported by the Spanish projects MicroDiff (REN2001-2110/MAR) and MODIVUS (CTM2005-04975/MAR), and the EU project BASICS (EVK3-CT-2002-00078) to J.M.G., GENμMAR (CTM2004-02586/MAR) to C.P.A. and ESTRAMAR to R.M. (CTM2004-12631/MAR). This is also a contribution to the NoE MARBEF. Financial support was provided by a PhD fellowship from the Spanish government to L.A.S.Peer reviewe

Marine heterotrophic bacteria synthesize non-phosphorus lipids upon phosphorus stress

Aquatic Sciences Meeting, Aquatic Sciences: Global And Regional Perspectives - North Meets South, 22-27 February 2015, Granada, SpainPhosphorus (P) is an essential nutrient for life. The replacement of membrane phospholipids with non-phosphorus lipids constitutes an important strategy to allow growth on phosphate-limited environments. In the ocean, this strategy has been reported in phytoplankton, but not in heterotrophic bacteria. A phospholipase C was recently identified to be required for lipid remodelling in a soil bacterium during P-limitation. In this study we show this enzyme is widespread in bacterial taxa and frequently found in ocean metagenomes. In SAR11 and other proteobacterial isolates, this gene is frequently neighbour to a glycosyltransferase that could be involved in glycolipid biosynthesis. Experiments with marine isolates showed up-regulation of transcription of both the phospholipase C and the glycosyltransferase upon P-starvation. These results suggest that marine heterotrophic bacteria may substitute phospholipids for glycolipids to reduce their P-demand. Lipid measurements in environmental samples confirmed that indeed there is an important enrichment in glycolipids in the heterotrophic bacterial fraction under P-depleted conditions. Hence, lipid remodelling seems to be a widespread mechanism among marine microbes for surviving in the vast oligotrophic areas of the oceanPeer Reviewe

Association of latitude and exposure to ultraviolet B radiation with severity of multiple sclerosis : an international registry study

Background and Objectives The severity of multiple sclerosis (MS) varies widely among individuals. Understanding the determinants of this heterogeneity will help clinicians optimize the management of MS. The aim of this study was to investigate the association between latitude of residence, UV B radiation (UVB) exposure, and the severity of MS. Methods This observational study used the MSBase registry data. The included patients met the 2005 or 2010 McDonald diagnostic criteria for MS and had a minimum dataset recorded in the registry (date of birth, sex, clinic location, date of MS symptom onset, disease phenotype at baseline and censoring, and >= 1 Expanded Disability Status Scale score recorded). The latitude of each study center and cumulative annualized UVB dose at study center (calculated from National Aeronautics and Space Administration's Total Ozone Mapping Spectrometer) at ages 6 and 18 years and the year of disability assessment were calculated. Disease severity was quantified with Multiple Sclerosis Severity Score (MSSS). Quadratic regression was used to model the associations between latitude, UVB, and MSSS. Results The 46,128 patients who contributed 453,208 visits and a cumulative follow-up of 351,196 patient-years (70% women, mean age 39.2 +/- 12 years, resident between latitudes 19 degrees 35 ' and 56 degrees 16 ') were included in this study. Latitude showed a nonlinear association with MS severity. In latitudes <40 degrees, more severe disease was associated with higher latitudes (beta = 0.08, 95% CI 0.04-0.12). For example, this translates into a mean difference of 1.3 points of MSSS between patients living in Madrid and Copenhagen. No such association was observed in latitudes <40 degrees (beta = -0.02, 95% CI -0.06 to 0.03). The overall disability accrual was faster in those with a lower level of estimated UVB exposure before the age of 6 years (beta = - 0.5, 95% CI -0.6 to 0.4) and 18 years (beta = - 0.6, 95% CI -0.7 to 0.4), as well as with lower lifetime UVB exposure at the time of disability assessment (beta = -1.0, 95% CI -1.1 to 0.9). Discussion In temperate zones, MS severity is associated with latitude. This association is mainly, but not exclusively, driven by UVB exposure contributing to both MS susceptibility and severity

Association of Latitude and Exposure to Ultraviolet B Radiation With Severity of Multiple Sclerosis An International Registry Study

Background and Objectives The severity of multiple sclerosis (MS) varies widely among individuals. Understanding the determinants of this heterogeneity will help clinicians optimize the management of MS. The aim of this study was to investigate the association between latitude of residence, UV B radiation (UVB) exposure, and the severity of MS. Methods This observational study used the MSBase registry data. The included patients met the 2005 or 2010 McDonald diagnostic criteria for MS and had a minimum dataset recorded in the registry (date of birth, sex, clinic location, date of MS symptom onset, disease phenotype at baseline and censoring, and >= 1 Expanded Disability Status Scale score recorded). The latitude of each study center and cumulative annualized UVB dose at study center (calculated from National Aeronautics and Space Administration's Total Ozone Mapping Spectrometer) at ages 6 and 18 years and the year of disability assessment were calculated. Disease severity was quantified with Multiple Sclerosis Severity Score (MSSS). Quadratic regression was used to model the associations between latitude, UVB, and MSSS. Results The 46,128 patients who contributed 453,208 visits and a cumulative follow-up of 351,196 patient-years (70% women, mean age 39.2 +/- 12 years, resident between latitudes 19 degrees 35 ' and 56 degrees 16 ') were included in this study. Latitude showed a nonlinear association with MS severity. In latitudes <40 degrees, more severe disease was associated with higher latitudes (beta = 0.08, 95% CI 0.04-0.12). For example, this translates into a mean difference of 1.3 points of MSSS between patients living in Madrid and Copenhagen. No such association was observed in latitudes <40 degrees (beta = -0.02, 95% CI -0.06 to 0.03). The overall disability accrual was faster in those with a lower level of estimated UVB exposure before the age of 6 years (beta = - 0.5, 95% CI -0.6 to 0.4) and 18 years (beta = - 0.6, 95% CI -0.7 to 0.4), as well as with lower lifetime UVB exposure at the time of disability assessment (beta = -1.0, 95% CI -1.1 to 0.9). Discussion In temperate zones, MS severity is associated with latitude. This association is mainly, but not exclusively, driven by UVB exposure contributing to both MS susceptibility and severity