Diversity and Distribution of Freshwater Aerobic Anoxygenic Phototrophic Bacteria across a Wide Latitudinal Gradient

12 pages, 5 figures, 1 tableAerobic anoxygenic phototrophs (AAPs) have been shown to exist in numerous marine and brackish environments where they are hypothesized to play important ecological roles. Despite their potential significance, the study of freshwater AAPs is in its infancy and limited to local investigations. Here, we explore the occurrence, diversity and distribution of AAPs in lakes covering a wide latitudinal gradient: Mongolian and German lakes located in temperate regions of Eurasia, tropical Great East African lakes, and polar permanently ice-covered Antarctic lakes. Our results show a widespread distribution of AAPs in lakes with contrasting environmental conditions and confirm that this group is composed of different members of the Alpha- and Betaproteobacteria. While latitude does not seem to strongly influence AAP abundance, clear patterns of community structure and composition along geographic regions were observed as indicated by a strong macro-geographical signal in the taxonomical composition of AAPs. Overall, our results suggest that the distribution patterns of freshwater AAPs are likely driven by a combination of small-scale environmental conditions (specific of each lake and region) and large-scale geographic factors (climatic regions across a latitudinal gradient)This work was partly supported through the IGB Fellowship Program in Freshwater Science funded to IF. Sampling expedition to the African lakes was funded by the Spanish Ministry of Science and Innovation (CGL2010-11556-E). Antarctic samples were collected as part of the US NSF funded McMurdo Dry Valleys Long-Term Ecological Research Program (NSF-PLR 1115245). [...] HS work was supported by CNPq and FAPESP (Process: 2014/14139-3).Peer Reviewe

Source of Lake Vostok Cations Constrained with Strontium Isotopes

Lake Vostok is the largest sub-glacial lake in Antarctica. The primary source of our current knowledge regarding the geochemistry and biology of the lake comes from the analysis of refrozen lake water associated with ice core drilling. Several sources of dissolved ions and particulate matter to the lake have been proposed, including materials from the melted glacier ice, the weathering of underlying geological materials, hydrothermal activity and underlying, ancient evaporitic deposits. A sample of Lake Vostok Type 1 accretion ice has been analyzed for its 87Sr/86Sr signature as well as its major cation and anion and Sr concentrations. The strontium isotope ratio of 0.71655 and the Ca/Sr ratio in the sample strongly indicate that the major source of the Sr is from aluminosilicate minerals from the continental crust. These data imply that at least a portion of the other cations in the Type 1 ice also are derived from continental crustal materials and not hydrothermal activity, the melted glacier ice, or evaporitic sources

Ciliate diversity, community structure, and novel taxa in lakes of the McMurdo Dry Valleys, Antarctica

Author Posting. © Marine Biological Laboratory, 2014. This article is posted here by permission of Marine Biological Laboratory for personal use, not for redistribution. The definitive version was published in Biological Bulletin 227 (2014): 175-190.We report an in-depth survey of next-generation DNA sequencing of ciliate diversity and community structure in two permanently ice-covered McMurdo Dry Valley lakes during the austral summer and autumn (November 2007 and March 2008). We tested hypotheses on the relationship between species richness and environmental conditions including environmental extremes, nutrient status, and day length. On the basis of the unique environment that exists in these high-latitude lakes, we expected that novel taxa would be present. Alpha diversity analyses showed that extreme conditions—that is, high salinity, low oxygen, and extreme changes in day length—did not impact ciliate richness; however, ciliate richness was 30% higher in samples with higher dissolved organic matter. Beta diversity analyses revealed that ciliate communities clustered by dissolved oxygen, depth, and salinity, but not by season (i.e., day length). The permutational analysis of variance test indicated that depth, dissolved oxygen, and salinity had significant influences on the ciliate community for the abundance matrices of resampled data, while lake and season were not significant. This result suggests that the vertical trends in dissolved oxygen concentration and salinity may play a critical role in structuring ciliate communities. A PCR-based strategy capitalizing on divergent eukaryotic V9 hypervariable region ribosomal RNA gene targets unveiled two new genera in these lakes. A novel taxon belonging to an unknown class most closely related to Cryptocaryon irritans was also inferred from separate gene phylogenies.Funding was provided by NSF DEB-0717390 to Linda Amaral-Zettler (MIRADA-LTERS); OPP-1115245, OPP-0838933, OPP-1027284, and OPP-0839075 to John C. Priscu; and OPP-0631659 and OPP-1056396 to Rachael Morgan-Kiss. We would also like to acknowledge the China Scholarship Council (No. [2012] 3013) for fellowship support to Yuan Xu enabling her to study at the Marine Biological Laboratory. The Montana Space Grant Consortium provided additional funding for Trista Vick-Majors

Modeling the Thickness of Perennial Ice Covers on Stratified Lakes of the Taylor Valley, Antarctica

A one-dimensional ice cover model was developed to predict and constrain drivers of long term ice thickness trends in chemically stratified lakes of Taylor Valley, Antarctica. The model is driven by surface radiative heat fluxes and heat fluxes from the underlying water column. The model successfully reproduced 16 years (between 1996 and 2012) of ice thickness changes for west lobe of Lake Bonney (average ice thickness = 3.53 m; RMSE = 0.09 m, n = 118) and Lake Fryxell (average ice thickness = 4.22 m; RMSE = 0.21 m, n = 128). Long-term ice thickness trends require coupling with the thermal structure of the water column. The heat stored within the temperature maximum of lakes exceeding a liquid water column depth of 20 m can either impede or facilitate ice thickness change depending on the predominant climatic trend (temperature cooling or warming). As such, shallow (< 20 m deep water columns) perennially ice-covered lakes without deep temperature maxima are more sensitive indicators of climate change. The long-term ice thickness trends are a result of surface energy flux and heat flux from the deep temperature maximum in the water column, the latter of which results from absorbed solar radiation

Microbial community composition of transiently wetted Antarctic Dry Valley soils

During the summer months, wet (hyporheic) soils associated with ephemeral streams and lake edges in the Antarctic Dry Valleys (DVs) become hotspots of biological activity and are hypothesized to be an important source of carbon and nitrogen for arid DV soils. Recent research in the DV has focused on the geochemistry and microbial ecology of lakes and arid soils, with substantially less information being available on hyporheic soils. Here, we determined the unique properties of hyporheic microbial communities, resolved their relationship to environmental parameters and compared them to archetypal arid DV soils. Generally, pH increased and chlorophyll a concentrations decreased along transects from wet to arid soils (9.0 to ~7.0 for pH and ~0.8 to ~5 μg/cm3 for chlorophyll a, respectively). Soil water content decreased to below ~3% in the arid soils. Community fingerprinting-based principle component analyses revealed that bacterial communities formed distinct clusters specific to arid and wet soils; however, eukaryotic communities that clustered together did not have similar soil moisture content nor did they group together based on sampling location. Collectively, rRNA pyrosequencing indicated a considerably higher abundance of Cyanobacteria in wet soils and a higher abundance of Acidobacterial, Actinobacterial, Deinococcus/Thermus, Bacteroidetes, Firmicutes, Gemmatimonadetes, Nitrospira, and Planctomycetes in arid soils. The two most significant differences at the genus level were Gillisia signatures present in arid soils and chloroplast signatures related to Streptophyta that were common in wet soils. Fungal dominance was observed in arid soils and Viridiplantae were more common in wet soils. This research represents an in-depth characterization of microbial communities inhabiting wet DV soils. Results indicate that the repeated wetting of hyporheic zones has a profound impact on the bacterial and eukaryotic communities inhabiting in these areas

Hipertensiunea pulmonară secundară bolii ischemice cardiace

În articol a fost prezentă sinteza asupra literaturii consacrate apariției hipertensiunii pulmonare (HTP) secundare patologiei cordului stâng. Astfel hipertensiunea pulmonară secundară patologiei cordului stâng este un factor constituţional care poate juca un rol în dezvoltarea HTP în cadrul acestui grup de pacienţi. Prevalenţa HTP la pacienţi cu insuficienţă cardiacă cronică creşte corespunzător clasei funcţionale. Prezența hipertensiunii pulmonare secundare bolii ischemice a cordului induce simptome mai severe a patologiei de bază cu scăderea toleranței la efort fizic, astfel exercitând un impact negativ asupra evoluției bolii. Menagementul pacienților cu HTP secundară BCI rămâne o problema medicala care are nevoie de o abordare specială bazată pe dovezi

Biogeochemical Stoichiometry of Antarctic Dry Valley Ecosystems

Among aquatic and terrestrial landscapes of the McMurdo Dry Valleys, Antarctica, ecosystem stoichiometry ranges from values near the Redfield ratios for C:N:P to nutrient concentrations in proportions far above or below ratios necessary to support balanced microbial growth. This polar desert provides an opportunity to evaluate stoichiometric approaches to understand nutrient cycling in an ecosystem where biological diversity and activity are low, and controls over the movement and mass balances of nutrients operate over 10–10⁶ years. The simple organisms (microbial and metazoan) comprising dry valley foodwebs adhere to strict biochemical requirements in the composition of their biomass, and when activated by availability of liquid water, they influence the chemical composition of their environment according to these ratios. Nitrogen and phosphorus varied significantly in terrestrial and aquatic ecosystems occurring on landscape surfaces across a wide range of exposure ages, indicating strong influences of landscape development and geochemistry on nutrient availability. Biota control the elemental ratio of stream waters, while geochemical stoichiometry (e.g., weathering, atmospheric deposition) evidently limits the distribution of soil invertebrates. We present a conceptual model describing transformations across dry valley landscapes facilitated by exchanges of liquid water and biotic processing of dissolved nutrients. We conclude that contemporary ecosystem stoichiometry of Antarctic Dry Valley soils, glaciers, streams, and lakes results from a combination of extant biological processes superimposed on a legacy of landscape processes and previous climates

Masonry dams : analysis of the historical profiles of Sazilly, Delocre and Rankine

The significant advances in masonry dam design that took place in the second half of the 19th century are analyzed and discussed within the context of the historical development of dam construction. Particular reference is made to the gravity dam profiles proposed by Sazilly, Delocre and Rankine, who pioneered the application of engineering concepts to dam design, basing the dam profile on the allowable stresses for the conditions of empty and full reservoir. These historical profiles are analyzed taking into consideration the present safety assessment procedures, by means of a numerical application developed for this purpose, based on limit analysis equilibrium methods, which considers the sliding failure mechanisms, the most critical for these structures. The study underlines the key role of uplift pressures, which was only addressed by Lévy after the accident of Bouzey dam, and provides a critical understanding of the original design concepts, which is essential for the rehabilitation of these historical structures.This work has been funded by FCT (Portuguese Foundation for Science and Technology) through the PhD grant SFRH/BD/43585/2008, for which the first author is grateful

THE PARTICULARITIES OF CONCENTIONAL AND DIGITAL FINGERPRINTING OF PROSTHETIC FIELD ELEMENTS

Universitatea de Stat de Medicină şi Farmacie „Nicolae Testemiţanu”, Chişinău, Republica MoldovaIntroducere. Amprentarea digitală a câmpului protetic (CAD/CAM - Computer-Aided Design & Computer-Aided Manufacturing) în stomatologie reprezintă utilizarea tehnologiei computerizate pentru a obține o amprentă precisă a elementelor câmpului protetic, necesară confecționării diverselor lucrări protetice dentare, cum ar fi protezele dentare fixe (coroane, punți dentare, etc.). Tehnica clasică de amprentare implică utilizarea materialelor de amprentare și a lingurii amprentare, cu obținerea amprentei, iar apoi aceasta este utilizată pentru a crea un model din ghips în laboratorul dentar, pentru a confecționa lucrarea protetică necesară. Există mai multe avantaje ale amprentării digitale în stomatologie: confort pentru pacienți, precizie și acuratețe, eficiență și rapiditate, personalizare și colaborare. Scopul lucrării. Identificarea celei mai eficiente și precise metode de amprentare a câmpului protetic. Material și metode. Metodele de scanare utilizate în amprentarea digitală a elementelor câmpului protetic sunt următoarele: scanearea intraorală, scanarea extraorală, tehnica de fotografiere digitală, utilizând - scanerul intraoral, pudră de scanare și geluri de amprentă. Rezultate. Amprentarea digitală este o metodă inovativă în comparație cu amprentarea clasică a câmpului protetic, deoarece aceasta poate oferi informații importante pentru autentificare, identificare și analiză într-o varietate de domenii. Utilizarea amprentelor digitale ca mijloc de verificare și identificare se bazează pe unicitatea și stabilitatea acestora. Cu toate acestea, este important să se țină cont de limitele și posibilitatea existenței erorilor în procesul de amprentare digitală. Concluzii. În concluzie, amprentarea digitală în stomatologie oferă numeroase avantaje versus metodelor tradiționale de amprentare clasică în ceea ce privește confortul pacienților, precizia și acuratețea, economisirea de timp și resurse, eliminarea erorilor umane și posibilitatea de planificare computerizată a tratamentelor protetice.Background. Digital imprinting of the prosthetic field (CAD/CAM - Computer-Aided Design & Computer-Aided Manufacturing) in Stomatology represents the use of computerized technology to obtain a precise impression of the prosthetic field elements, necessary for the fabrication of various dental prosthetic works, such as fixed dental prostheses (crowns, bridges, etc.). The traditional impression technique involves the use of impression materials and impression trays to obtain the impression, which is then used to create a gypsum model in the dental laboratory for the fabrication of the required prosthetic work. There are several advantages of digital imprinting in Stomatology: patient comfort, precision and accuracy, efficiency and speed, customization and collaboration. Objective of the study. Identifying the most efficient and precise method of imprinting the prosthetic field. Material and methods. The scanning methods used in digital imprinting of the prosthetic field are as follows: intraoral scanning, extraoral scanning, digital photography technique using an intraoral scanner, scanning powder, and impression gels. Results. Digital imprinting is an innovative method compared to the traditional imprinting of the prosthetic field because it can provide important information for authentication, identification, and analysis in a variety of fields. The use of digital imprints as a means of verification and identification is based on their uniqueness and stability. However, it is important to consider the limitations and the possibility of errors in the digital imprinting process. Conclusion. In conclusion, digital imprinting in Stomatology offers numerous advantages over traditional methods of classic imprinting in terms of patient comfort, precision and accuracy, time and resource savings, elimination of human errors, and the possibility of computerized treatment planning

Cementless porous concrete

Сharacteristic of the resulting air-mechanical foam. Effect of a sealing compound type on the properties of the foam. Influence of the material composition of molding masses on the properties of alkali-silicate compositions. Effect of filler type on the properties of alkali-silicate compositions. Three tables. Characterization foam concrete on the basis of the combined filler. Сharacterization of the studied of alkali-silicate compositions