Background and AimsAbiotic properties of soil are known to be major drivers of the microbial community within it. Our understanding of how soil microbial properties are related to the functional ...structure and diversity of plant communities, however, is limited and largely restricted to above-ground plant traits, with the role of below-ground traits being poorly understood. This study investigated the relative contributions of soil abiotic properties and plant traits, both above-ground and below-ground, to variations in microbial processes involved in grassland nitrogen turnover.MethodsIn mountain grasslands distributed across three European sites, a correlative approach was used to examine the role of a large range of plant functional traits and soil abiotic factors on microbial variables, including gene abundance of nitrifiers and denitrifiers and their potential activities.Key ResultsDirect effects of soil abiotic parameters were found to have the most significant influence on the microbial groups investigated. Indirect pathways via plant functional traits contributed substantially to explaining the relative abundance of fungi and bacteria and gene abundances of the investigated microbial communities, while they explained little of the variance in microbial activities. Gene abundances of nitrifiers and denitrifiers were most strongly related to below-ground plant traits, suggesting that they were the most relevant traits for explaining variation in community structure and abundances of soil microbes involved in nitrification and denitrification.ConclusionsThe results suggest that consideration of plant traits, and especially below-ground traits, increases our ability to describe variation in the abundances and the functional characteristics of microbial communities in grassland soils.
Beetle luciferases elicit the emission of different bioluminescence colors from green to red. Whereas firefly luciferases emit yellow-green light and are pH-sensitive, undergoing a typical red-shift ...at acidic pH and higher temperatures and in the presence of divalent heavy metals, click beetle and railroadworm luciferases emit a wider range of colors from green to red but are pH-independent. Despite many decades of study, the structural determinants and mechanisms of bioluminescence colors and pH sensitivity remain enigmatic. Here, through modeling studies, site-directed mutagenesis, and spectral and kinetic studies using recombinant luciferases from the three main families of bioluminescent beetles that emit different colors of light (Macrolampis sp2 firefly, Phrixotrix hirtus railroadworm, and Pyrearinus termitilluminans click beetle), we investigated the role of E311 and R337 in bioluminescence color determination. All mutations of these residues in firefly luciferase produced red mutants, indicating that the preservation of opposite charges and the lengths of the side chains of E311 and R337 are essential for keeping a salt bridge that stabilizes a closed hydrophobic conformation favorable for green light emission. Kinetic studies indicate that residue R337 is important for binding luciferin and creating a positively charged environment around excited oxyluciferin phenolate. In Pyrearinus green-emitting luciferase, the R334A mutation causes a 27 nm red-shift, whereas in Phrixotrix red-emitting luciferase, the L334R mutation causes a blue-shift that is no longer affected by guanidine. These results provide compelling evidence that the presence of arginine at position 334 is essential for blue-shifting the emission spectra of most beetle luciferases. Therefore, residues E311 and R337 play both structural and catalytic roles in bioluminescence color determination, by stabilizing a closed hydrophobic conformation favorable for green light emission, and also providing a base to accept excited oxyluciferin phenol proton, and a countercation to shield the negative charge of E311 and to stabilize excited oxyluciferin phenolate, blue-shifting emission spectra in most beetle luciferases.
Firefly luciferases usually produce bioluminescence in the yellow-green region, with colors in the green and yellow-orange extremes of the spectrum being less common. Several firefly luciferases have ...already been cloned and sequenced, and site-directed mutagenesis studies have already identified important regions and residues for bioluminescence colors. However the structural determinants and mechanisms of bioluminescence colors turned out to be elusive, mainly when comparing luciferases with a high degree of divergence. Thus comparison of more similar luciferases producing colors in the two extremes of the spectrum could be revealing. The South-American fauna of fireflies remains largely unstudied, with some unique taxa that are not found anywhere else in the world and that produce a wide range of bioluminescence colors. Among them, fireflies of the genus Amydetes are especially interesting because its taxonomical status as an independent subfamily or as a tribe is not yet solved, and because they usually produce a continuous bright blue-shifted bioluminescence. In this work we cloned the cDNA for the luciferase of the Atlantic rain forest Amydetes fanestratus firefly, which is found near Sorocaba municipality (São Paulo, Brazil). Despite showing a higher degree of identity with the South-American Cratomorphus, the European Lampyris and the Asiatic Pyrocoelia, phylogenetical analysis of the luciferase sequence support the inclusion of Amydetes as an independent subfamily. Amydetes luciferase displays one of the most blue-shifted emission spectra (λ(max) = 538 nm) among beetle luciferases, with lower pH-sensitivity and higher affinity for ATP when compared to other luciferases, making this luciferase attractive for sensitive ATP and reporter assays.
OBJECTIVE:Left atrial (LA) enlargement (LAE) is associated to an increased risk of cardiovascular complications, and in particular of atrial fibrillation. The 2018 ESH/ESC Hypertension guidelines ...suggested the use of LA volume instead of linear dimensions, and for the first time proposed the indexation to height2(h2)The aim of our study was to assess the prevalence of left atrial dilatation in a large sample of patients undergoing an echocardiogram for cardiovascular risk stratification at an ESH excellence centre in Italy.
DESIGN AND METHOD:3872 subjects undergoing a diagnostic work-up for arterial hypertension (known or suspect) were analysed. The mean age was 56 ± 15 years, BMI 26 ± 5, 44% normal weight, 39% overweight, 17% obese, 53% males. Left atrial volume was measured by the area-length method using the apical 4-chamber and 2-chamber views.
RESULTS:The prevalence of left ventricular hypertrophy (LVH) was 11% when indexing for BSA and 12% when indexing for height2.7. LAE was observed in 30% of subjects when indexing for h2 and in 9% when indexing for BSA. In obese or overweight subjects the prevalence of LAE was 38% of subjects when indexing for h2 and in 11% when indexing for BSA. The different prevalence of LAE was particularly evident in extremely obese patients.LAE was very common in patients with LVH62% and 26% when indexing for h2 and for BSA, respectively. Interestingly, it was frequent also in patients without LVH, in particular when the indexation for h2 was used (25% as compared to 7% when indexing for BSA).
CONCLUSIONS:In a large sample of subjects undergoing a diagnostic work-up for arterial hypertension LAE was frequently observed, particularly when the new indexation proposed by the 2018 ESH/ESC hypertension guidelines was used. Even in the absence of clear-cut LVH, LAE was observed in one quarter of subjects. The indexation to BSA leads to an under-recognition of LAE, in particular in patients with overweight and/or obesity.
OBJECTIVE:It has been suggested that measurement of “unattended” or “automated oscillatory(AOBP)” blood pressure values may provide advantages over conventional BP measurement and some hypertension ...guidelines now suggest this approach as the preferred one for measuring office BP. Data on the strength of the relationship between AOBP and cardiovascular events are limited as compared to those obtained with the standard BP measurement; conflicting data are available on the relationship between hypertensive organ damage and “attended” and “unattended” BP.The aim of our study was to evaluate the relationship between “attended” or “unattended” BP values and arterial stiffness in 108 subjects undergoing a visit and assessment of arterial stiffness at an ESH Excellence Centre.
DESIGN AND METHOD:Both “unattended” BP (patient alone in the room, an oscillometric device programmed to perform 3 BP measurements, at 1 minute intervals, after 5 minutes) and “attended” BP were measured with the same device, on the same day of arterial stiffness assessment, in random order.
RESULTS:Patientʼs mean age was 65 ± 15 yrs, mean BMI 26 ± 4, 43% female, 72 % had hypertension (59% treated). Systolic unattended BP was lower as compared to attended SBP (132.7 ± 17.7vs124.9 ± 15.3 mmHg). A similar correlation was observed between PWV and systolic unattended BP or attended SBP (r = 0.530 and r = 0.535, p < 0.0001, respectively) and between PWV and mean unattended and attended BP (r = 0.408 and r = 0.381, p < 0.0001, respectively). Similar correlations were also observed between PWV and unattended and attended pulse pressure (r = 0.459 and r = 0.480, p < 0.0001). The differences between correlations were not statistically significant (Steigerʼs Z test).No significant difference was observed between the ROC curves of attended and unattended SBP for the presence of increased arterial stiffness (AUC 0.706 vs. AUC 0.730, p for the comparison = ns).
CONCLUSIONS:Measurement of BP “unattended” or “unattended” provides different values, being unattended BP lower as compared to attended BP. Our results suggest that unattended measurement of BP values does not change the relationship with the gold standard measure of arterial stiffness.
•Plant species identities effects on soil microbial properties were assessed.•Bacterial activities were influenced by specific above-ground plant traits.•Mycorrhizal colonization was influenced by ...below-ground traits.•Plant species effects may be linked to inter-specific differences in plant traits
Plant species influence soil microbial communities, mainly through their functional traits. However, mechanisms underlying these effects are not well understood, and in particular how plant/microorganism interactions are affected by plant identities and/or environmental conditions. Here, we performed a greenhouse experiment to assess the effects of three plant species on arbuscular mycorrhizal fungal (AMF) colonization, bacterial potential nitrification (PNA) and denitrification activities (PDA) through their functional traits related to nitrogen acquisition and turnover. Three species with contrasting functional traits and strategies (from exploitative to conservative), Dactylis glomerata (L.), Bromus erectus (Hudson) and Festuca paniculata (Schinz and Tellung), were cultivated in monocultures on soil grassland with or without N fertilization. Fertilization impacted some plant traits related to nutrient cycling (leaf and root N concentration, root C:N) but did not affect directly microbial parameters. The highest PDA and PNA were observed in D. glomerata and F. paniculata monocultures, respectively. The highest AMF colonization was obtained for F. paniculata, while B. erectus exhibited both the lowest AMF colonization and bacterial activities. Bacterial activities were influenced by specific above-ground plant traits across fertilization treatments: above-ground biomass for PDA, shoot:root ratio and leaf C:N ratio for PNA. Mycorrhizal colonization was influenced by below-ground traits either root dry matter content or root C:N. Hence, AMF colonization and bacterial activities were impacted differently by species-specific plant biomass allocation, root traits and nutrient requirement. We suggest that such effects may be linked to distinct root exudation patterns and plant abilities for nutrient acquisition and/or nutrient competition.
Correction for ‘A new blue-shifted luciferase from the Brazilian
Amydetes fanestratus
(Coleoptera: Lampyridae) firefly: molecular evolution and structural/functional properties’ by Vadim R. Viviani
...et al., Photochem. Photobiol. Sci.
, 2011,
10
, 1879–1886.
Firefly luciferases are called pH-sensitive because their bioluminescence spectra display a typical red-shift at acidic pH, higher temperatures, and in the presence of heavy metal cations, whereas ...other beetle luciferases (click beetles and railroadworms) do not, and for this reason they are called pH-insensitive. Despite many studies on firefly luciferases, the origin of pH-sensitivity is far from being understood. This subject is revised in view of recent results. Some substitutions of amino-acid residues influencing pH-sensitivity in firefly luciferases have been identified. Sequence comparison, site-directed mutagenesis and modeling studies have shown a set of residues differing between pH-sensitive and pH-insensitive luciferases which affect bioluminescence colors. Some substitutions dramatically affecting bioluminescence colors in both groups of luciferases are clustered in the loop between residues 223-235 (Photinus pyralis sequence). A network of hydrogen bonds and salt bridges involving the residues N229-S284-E311-R337 was found to be important for affecting bioluminescence colors. It is suggested that these structural elements may affect the benzothiazolyl side of the luciferin-binding site affecting bioluminescence colors. Experimental evidence suggest that the residual red light emission in pH-sensitive luciferases could be a vestige that may have biological importance in some firefly species. Furthermore, the potential utility of pH-sensitivity for intracellular biosensing applications is considered.
Among bioluminescent beetles of Elateroidea superfamily, railroad-worms (Phengodidae) produce the widest range of colors, from green to red, using the same luciferin-luciferase system. Members of the ...Mastinocerini tribe display additional unique cephalic organs that emit red-shifted light, with Phrixothrix railroad-worms being the most dramatic cases with head lanterns emitting red light. Although the luciferases from the head lanterns of Phrixothrix hirtus and from the lateral lanterns of P. vivianii were previously cloned, the luciferases from both lanterns of the same species were not cloned yet. Therefore the origin and evolution of head and lateral lanterns luciferases in Phengodidae remains unknown. In the present work, we cloned by PCR the cDNA for lateral lantern luciferases of three Mastinocerini species: Phrixothrix hirtus, Brasilocerus sp(3). and Taximastioncerus sp. The results suggest that the head and lateral lanterns luciferases in Mastinocerini are coded by paralogous genes, and that the ancestral luciferase in the Phengodinae subfamily produced green bioluminescence. The evolutionary history of bioluminescence colors within Phengodinae is discussed.
Beetle luciferases emit a wide range of bioluminescence colors, ranging from green to red. Firefly luciferases can shift the spectrum to red in response to pH and temperature changes, whereas click ...beetle and railroadworm luciferases do not. Despite many studies on firefly luciferases, the origin of pH‐sensitivity is far from being understood. Through comparative site‐directed mutagenesis and modeling studies, using the pH‐sensitive luciferases (Macrolampis and Cratomorphus distinctus fireflies) and the pH‐insensitive luciferases (Pyrearinus termitilluminans, Phrixotrix viviani and Phrixotrix hirtus) cloned by our group, here we show that substitutions dramatically affecting bioluminescence colors in both groups of luciferases are clustered in the loop between residues 223‐235 (Photinus pyralis sequence). The substitutions at positions 227, 228 and 229 (P. pyralis sequence) cause dramatic redshift and temporal shift in both groups of luciferases, indicating their involvement in labile interactions. Modeling studies showed that the residues Y227 and N229 are buried in the protein core, fixing the loop to other structural elements participating at the bottom of the luciferin binding site. Changes in pH and temperature (in firefly luciferases), as well as point mutations in this loop, may disrupt the interactions of these structural elements exposing the active site and modulating bioluminescence colors.
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