Observational evidence linking ocean sulfur compounds to atmospheric dimethyl sulfide during Icelandic Sea phytoplankton blooms.

In two Icelandic Sea spring blooms (May 2018 and 2019) in the North Atlantic Ocean (62.9-68.0°N, 9.0-28.0°W), chlorophyll-a and dimethylsulfoniopropionate (DMSP) concentrations and DMSP lyase activity (the DMSP-to-dimethyl sulfide (DMS) conversion efficiency) were measured at 67 stations, and the hourly atmospheric DMS mixing ratios were concurrently measured only in May 2019 at Storhofdi on Heimaey Island, located south of Iceland (63.4°N, 20.3°W). The ocean parameters for biology (i.e., chlorophyll-a, DMSP, and DMSP lyase activity) were broadly associated in distribution; however, the statistical significance of the association differed among four ocean domains and also between 2018 and 2019. Specifically, the widespread dominance of Phaeocystis, coccolithophores, and dinoflagellates (all rich in DMSP and high in DMSP lyase activity) across the study area is a compelling indication that variations in DMSP-rich phytoplankton were likely a main cause of the variations in statistical significance. For all the ocean domains defined here, we found that the DMS production capacity (calculated using the exposures of air masses to ocean biology prior to their arrivals at Heimaey and the atmospheric DMS mixing ratios of those air masses at Heimaey) was surprisingly consistent with in situ ocean S data (i.e., DMSP and DMSP lyase activity). Our study shows that the proposed computational approach enabled the detection of changes in DMS production and emission in association with changes in ocean primary producers.

[Migraine prevalence, migraine incidence and migraine drug prescriptions in primary care in the capital region of Iceland].

INTRODUCTION: The study aim was to describe migraine incidence over the ten-year periods, 2000-2009 and 2010-2019, in individuals aged 10-79 years in primary healthcare centre (PHCC) Sólvangur and Fjörður, Hafnarfirði. Another aim was to estimate migraine prevalence in primary care clinics in the capital area of Iceland over the period 2010-2019 and describe prescriptions for migraine specific drugs and other drugs used for migraine. MATERIAL AND METHODS: This is a retrospective study based on data from medical records from the primary care clinics of the capital region of Iceland. The cohort consisted of individuals aged 10-79 years who were diagnosed with migraine, G43 according to the ICD-10 classification system. RESULTS: Migraine incidence at age 10-79 years over the ten-year period 2000-2009 at the primary care clinic Sólvangur was estimated 3.4 cases per 1000 person-years, during the period 2010-2019 in both Sólvangur and Fjörður clinics migraine incidence was estimated 2.9 cases per 1000 person-years. Increase was shown between the two periods in prescriptions of triptan drugs, opioids, and beta-blockers, where two-thirds of the migraineurs got prescription over the two periods. Women were three times more likely to be diagnosed with migraine than men, but men were diagnosed at younger age than women. Migraine prevalence at age 10-79 years in PHCCs in the capital area of Iceland was 4.4% over the period 2010-2019. CONCLUSION: Migraine prevalence in the PHCCs of the capital area of Iceland was only one third of migraine prevalence in the population-based cohort pilot study Heilsusaga Íslendinga. Increase in opioid drug prescriptions for individuals diagnosed with migraine is of concern and needs further study.

Rhodocaloribacter litoris gen. nov., sp. nov., isolated from an intertidal hot spring.

Red-pigmented strains of non-sporeforming, aerobic, chemoorganotrophic bacteria were isolated from intertidal hot springs in Laugarvík, NW-Iceland. Cells stained Gram-negative and formed pleomorphic rods that often had swollen ends and occurred singly or in filaments. Growth was observed at 40-65 °C (optimum at 60 °C), pH 6-9 (optimum at 6.5-8) and 0.5-5% (optimum at 1-2%) (w/v) NaCl. Strain ISCAR-4553T contained MK-7 as the main respiratory quinone and saturated iso and anteiso branched chains of 17 and 15 carbons as the main cellular fatty acids (83.4%). The G+C content of the DNA is 67.3 mol%. The highest 16S rRNA gene sequence similarity was with the genus Roseithermus (92.0%) and followed by Rhodothermus, Rubrivirga and Rubricoccus (88-90%). Genome and phenotype comparisons supported the affiliation of the novel isolates and the genus Roseithermus to the family Rhodothermaceae of the phylum Rhodothermaeota. The described isolates are proposed to be classified as representatives of a novel species belonging to a novel genus, with the name Rhodocaloribacter litoris gen. nov., sp. nov. The type strain is ISCAR-4553T (=DSM 110790T = ATCC TSD-179T).

Contrasting drivers and trends of ocean acidification in the subarctic Atlantic.

The processes of warming, anthropogenic CO2 (Canth) accumulation, decreasing pHT (increasing [H+]T; concentration in total scale) and calcium carbonate saturation in the subarctic zone of the North Atlantic are unequivocal in the time-series measurements of the Iceland (IS-TS, 1985-2003) and Irminger Sea (IRM-TS, 1983-2013) stations. Both stations show high rates of Canth accumulation with different rates of warming, salinification and stratification linked to regional circulation and dynamics. At the IS-TS, advected and stratified waters of Arctic origin drive a strong increase in [H+]T, in the surface layer, which is nearly halved in the deep layer (44.7 ± 3.6 and 25.5 ± 1.0 pmol kg-1 yr-1, respectively). In contrast, the weak stratification at the IRM-TS allows warming, salinification and Canth uptake to reach the deep layer. The acidification trends are even stronger in the deep layer than in the surface layer (44.2 ± 1.0 pmol kg-1 yr-1 and 32.6 ± 3.4 pmol kg-1 yr-1 of [H+]T, respectively). The driver analysis detects that warming contributes up to 50% to the increase in [H+]T at the IRM-TS but has a small positive effect on calcium carbonate saturation. The Canth increase is the main driver of the observed acidification, but it is partially dampened by the northward advection of water with a relatively low natural CO2 content.

Global variability in seawater Mg:Ca and Sr:Ca ratios in the modern ocean.

Seawater Mg:Ca and Sr:Ca ratios are biogeochemical parameters reflecting the Earth-ocean-atmosphere dynamic exchange of elements. The ratios' dependence on the environment and organisms' biology facilitates their application in marine sciences. Here, we present a measured single-laboratory dataset, combined with previous data, to test the assumption of limited seawater Mg:Ca and Sr:Ca variability across marine environments globally. High variability was found in open-ocean upwelling and polar regions, shelves/neritic and river-influenced areas, where seawater Mg:Ca and Sr:Ca ratios range from ∼4.40 to 6.40 mmol:mol and ∼6.95 to 9.80 mmol:mol, respectively. Open-ocean seawater Mg:Ca is semiconservative (∼4.90 to 5.30 mol:mol), while Sr:Ca is more variable and nonconservative (∼7.70 to 8.80 mmol:mol); both ratios are nonconservative in coastal seas. Further, the Ca, Mg, and Sr elemental fluxes are connected to large total alkalinity deviations from International Association for the Physical Sciences of the Oceans (IAPSO) standard values. Because there is significant modern seawater Mg:Ca and Sr:Ca ratios variability across marine environments we cannot absolutely assume that fossil archives using taxa-specific proxies reflect true global seawater chemistry but rather taxa- and process-specific ecosystem variations, reflecting regional conditions. This variability could reconcile secular seawater Mg:Ca and Sr:Ca ratio reconstructions using different taxa and techniques by assuming an error of 1 to 1.50 mol:mol, and 1 to 1.90 mmol:mol, respectively. The modern ratios' variability is similar to the reconstructed rise over 20 Ma (Neogene Period), nurturing the question of seminonconservative behavior of Ca, Mg, and Sr over modern Earth geological history with an overlooked environmental effect.

Large-scale production of a thermostable Rhodothermus marinus cellulase by heterologous secretion from Streptomyces lividans.

BACKGROUND: The gene encoding a thermostable cellulase of family 12 was previously isolated from a Rhodothermus marinus through functional screening. CelA is a protein of 260 aminoacyl residues with a 28-residue amino-terminal signal peptide. Mature CelA was poorly synthesized in some Escherichia coli strains and not at all in others. Here we present an alternative approach for its heterologous production as a secreted polypeptide in Streptomyces. RESULTS: CelA was successfully over-expressed as a secreted polypeptide in Streptomyces lividans TK24. To this end, CelA was fused C-terminally to the secretory signal peptide of the subtilisin inhibitor protein (Sianidis et al. in J Biotechnol. 121: 498-507, 2006) from Streptomyces venezuelae and a new cloning strategy developed. Optimal growth media and conditions that stall biomass production promote excessive CelA secretion. Under optimal growth conditions in nutrient broth medium, significant amounts of mature CelA (50-90 mg/L or 100-120 mg/g of dry cell weight) are secreted in the spent growth media after 7 days. A protocol to rapidly purify CelA to homogeneity from culture supernatants was developed and specific anti-sera raised against it. Biophysical, biochemical and immmuno-detection analyses indicate that the enzyme is intact, stable and fully functional. CelA is the most thermostable heterologous polypeptide shown to be secreted from S. lividans. CONCLUSION: This study further validates and extends the use of the S. lividans platform for production of heterologous enzymes of industrial importance and extends it to active thermostable enzymes. This study contributes to developing a platform for poly-omics analysis of protein secretion in S. lividans.

Nitrogen depletion and small R3-MYB transcription factors affecting anthocyanin accumulation in Arabidopsis leaves.

Ternary complexes consisting of a R2R3-MYB, a bHLH and a WD40 protein (MBW complexes) regulate trichome formation and anthocyanin synthesis in plants. Small R3-MYBs interact with the MBW complexes to exert a negative feedback, and thereby participate in regulation of epidermal cell fate, for example trichome numbers and clustering in leaves. In Arabidopsis thaliana, GL3, a bHLH transcription factor, is important in the MBW complex regulating trichome formation as well as in the MBW complex induced by nitrogen depletion and promoting anthocyanin formation. The small R3-MYBs: CPC, TRY, ETC1, ETC2, ETC3/CPL3, TCL1, MYBL2, are all known to interact with GL3. We here investigated these R3-MYBs in leaves of Arabidopsis rosette stage plants under nitrogen depletion to examine if the small MYBs would interfere with anthocyanin accumulation in plants under normal (autotrophic) growth conditions. CPC expression was enhanced two-fold in response to nitrogen depletion, and ETC3/CPL3 expression was enhanced by almost an order of magnitude (9×). Knockout of ETC3/CPL3 did not influence anthocyanin accumulation, but the results establish ETC3/CPL3 as a nitrate regulated gene and a putative candidate for being involved in nitrate status signaling and root development. Other R3-MYBs tested were not significantly influenced by nitrogen depletion. In conclusion, only CPC expression increased and clearly exerted a negative feedback on anthocyanin accumulation during nitrogen starvation in rosette leaves.