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1.
Polymers (Basel) ; 16(9)2024 May 05.
Article in English | MEDLINE | ID: mdl-38732761

ABSTRACT

This paper presents a comprehensive review of natural fiber-reinforced composites (NFRCs) for lower-limb prosthetic designs. It covers the characteristics, types, and properties of natural fiber-reinforced composites as well as their advantages and drawbacks in prosthetic designs. This review also discusses successful prosthetic designs that incorporate NFRCs and the factors that make them effective. Additionally, this study explores the use of computational biomechanical models to evaluate the effectiveness of prosthetic devices and the key factors that are considered. Overall, this document provides a valuable resource for anyone interested in using NFRCs for lower-limb prosthetic designs.

2.
mSphere ; 9(2): e0072723, 2024 Feb 28.
Article in English | MEDLINE | ID: mdl-38206053

ABSTRACT

Global change exposes ecosystems to changes in the frequency, magnitude, and concomitancy of disturbances, which impact the composition and functioning of these systems. Here, we experimentally evaluate the effects of salinity disturbances and eutrophication on bacterial communities from coastal ecosystems. The functional stability of these communities is critically important for maintaining water quality, productivity, and ecosystem services, such as fishery yields. Microbial functional stability can be maintained via resistance and resilience, which are reflected in genomic traits such as genome size and codon usage bias and may be linked to metabolic costs. However, little is known about the mechanisms that select these traits under varying nutrient regimes. To study the impact of pulsed disturbances on community assembly and functioning depending on metabolic costs, we performed a 41-day pulse disturbance experiment across two levels of resource availability. Our setup triggered stochastic community re-assembly processes in all treatments. In contrast, we observed consistent and resource availability-dependent patterns of superordinate community functioning and structural patterns, such as functional resistance in response to disturbances, genomic trait distributions, and species diversity. Predicted genomic traits reflected the selection for taxa possessing resistant- and resilience-related traits, particularly under high nutrient availability. Our findings are a step toward unraveling the compositional and genomic underpinnings of functional resistance in microbial communities after exposure to consecutive pulse disturbances. Our work demonstrates how resource availability alleviates metabolic constraints on resistance and resilience, and this has important consequences for predicting water quality and ecosystem productivity of environments exposed to global change. IMPORTANCE: Understanding the communities' responses to disturbances is a prerequisite to predicting ecosystem dynamics and, thus, highly relevant considering global change. Microbial communities play key roles in numerous ecosystem functions and services, and the large diversity, rapid growth, and phenotypic plasticity of microorganisms are thought to allow high resistance and resilience. While potential metabolic costs associated with adaptations to fluctuating environments have been debated, little evidence supports trade-offs between resource availability, resistance, and resilience. Here, we experimentally assessed the compositional and functional responses of an aquatic microbial model community to disturbances and systematically manipulated resource availability. Our results demonstrate that the capacity to tolerate environmental fluctuations is constrained by resource availability and reflected in the selection of genomic traits.


Subject(s)
Biodiversity , Microbiota , Bacteria/genetics , Bacteria/metabolism , Adaptation, Physiological
3.
Bioelectrochemistry ; 157: 108636, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38181591

ABSTRACT

Pseudomonas aeruginosa phenazines contribute to survival under microaerobic and anaerobic conditions by extracellular electron discharge to regulate cellular redox balances. This electron discharge is also attractive to be used for bioelectrochemical applications. However, elements of the respiratory pathways that interact with phenazines are not well understood. Five terminal oxidases are involved in the aerobic electron transport chain (ETC) of Pseudomonas putida and P. aeruginosa. The latter bacterium also includes four reductases that allow for denitrification. Here, we explored if phenazine-1-carboxylic acid interacts with those elements to enhance anodic electron discharge and drive bacterial growth in oxygen-limited conditions. Bioelectrochemical evaluations of terminal oxidase-deficient mutants of both Pseudomonas strains and P. aeruginosa with stimulated denitrification pathways indicated no direct beneficial interaction of phenazines with ETC elements for extracellular electron discharge. However, the single usage of the Cbb3-2 oxidase increased phenazine production, electron discharge, and cell growth. Assays with purified periplasmic cytochromes NirM and NirS indicated that pyocyanin acts as their electron donor. We conclude that phenazines play an important role in electron transfer to, between, and from terminal oxidases under oxygen-limiting conditions and their modulation might enhance EET. However, the phenazine-anode interaction cannot replace oxygen respiration to deliver energy for biomass formation.


Subject(s)
Pseudomonas aeruginosa , Pseudomonas putida , Electron Transport , Pseudomonas aeruginosa/metabolism , Pseudomonas putida/metabolism , Electrons , Phenazines , Oxygen/metabolism
4.
Microbiol Resour Announc ; 13(1): e0071523, 2024 Jan 17.
Article in English | MEDLINE | ID: mdl-38054710

ABSTRACT

This study reports the complete genome of Flavobacterium pectinovorum str. ZE23VCel01 isolated from a freshwater environment. By means of Nanopore Q20+ chemistry, the chromosome was assembled as a circular element with a length of 5.9 Mbp, a GC content of 33.58%, and a coverage of 122×.

5.
Microbiol Resour Announc ; 13(1): e0071623, 2024 Jan 17.
Article in English | MEDLINE | ID: mdl-38038468

ABSTRACT

Herein, we document the complete genome of the Flavobacterium strain ZE23DGlu08, isolated from Lake Zurich, Switzerland. The circular genome was assembled using long-read Nanopore data (coverage: 226×) with the Q20+ chemistry. The described strain displays a genome size of ~3.9 Mbp with a GC content of 34%.

6.
Microbiol Resour Announc ; 12(11): e0071423, 2023 Nov 16.
Article in English | MEDLINE | ID: mdl-37819117

ABSTRACT

Here, we report the complete genome of Pseudomonas kielensis str. Ze23jcel16 isolated from a freshwater sample. The high-quality chromosome was obtained employing R10.4.1 Nanopore Flow cell chemistry and was assembled as a circular element at 45× coverage, a length of 5.8 Mbp, and a G+C content of 61.15%.

7.
Microbiol Resour Announc ; 12(10): e0071723, 2023 Oct 19.
Article in English | MEDLINE | ID: mdl-37772872

ABSTRACT

We present here the complete genome of Asticcacaulis sp. ZE23SCel15. The strain was isolated from the surface water of Lake Zurich, Switzerland. The assembly of high-quality Q20+ Nanopore data yielded a circular genome with ~3.8 Mb (coverage: 34×) and a GC content of 56.81%.

8.
Microb Biotechnol ; 16(3): 579-594, 2023 03.
Article in English | MEDLINE | ID: mdl-36571174

ABSTRACT

Mediated extracellular electron transfer (EET) might be a great vehicle to connect microbial bioprocesses with electrochemical control in stirred-tank bioreactors. However, mediated electron transfer to date is not only much less efficient but also much less studied than microbial direct electron transfer to an anode. For example, despite the widespread capacity of pseudomonads to produce phenazine natural products, only Pseudomonas aeruginosa has been studied for its use of phenazines in bioelectrochemical applications. To provide a deeper understanding of the ecological potential for the bioelectrochemical exploitation of phenazines, we here investigated the potential electroactivity of over 100 putative diverse native phenazine producers and the performance within bioelectrochemical systems. Five species from the genera Pseudomonas, Streptomyces, Nocardiopsis, Brevibacterium and Burkholderia were identified as new electroactive bacteria. Electron discharge to the anode and electric current production correlated with the phenazine synthesis of Pseudomonas chlororaphis subsp. aurantiaca. Phenazine-1-carboxylic acid was the dominant molecule with a concentration of 86.1 µg/ml mediating an anodic current of 15.1 µA/cm2 . On the other hand, Nocardiopsis chromatogenes used a wider range of phenazines at low concentrations and likely yet-unknown redox compounds to mediate EET, achieving an anodic current of 9.5 µA/cm2 . Elucidating the energetic and metabolic usage of phenazines in these and other species might contribute to improving electron discharge and respiration. In the long run, this may enhance oxygen-limited bioproduction of value-added compounds based on mediated EET mechanisms.


Subject(s)
Phenazines , Pseudomonas , Phenazines/metabolism , Pseudomonas/metabolism , Oxidation-Reduction
9.
Curr Issues Mol Biol ; 44(12): 5827-5838, 2022 Nov 22.
Article in English | MEDLINE | ID: mdl-36547057

ABSTRACT

Background: Achilles-tendon rupture prevails as a common tendon pathology. Adipose-derived mesenchymal stem cells (ADMSCs) are multipotent stem cells derived from adipose tissue with attractive regeneration properties; thus, their application in tendinopathies could be beneficial. Methods: Male rabbit ADMSCs were obtained from the falciform ligament according to previously established methods. After tenotomy and suture of the Achilles tendon, 1 × 106 flow-cytometry-characterized male ADMSCs were injected in four female New Zealand white rabbits in the experimental group (ADMSC group), whereas four rabbits were left untreated (lesion group). Confirmation of ADMSC presence in the injured site after 12 weeks was performed with quantitative sex-determining region Y (SRY)-gene RT-PCR. At Week 12, histochemical analysis was performed to evaluate tissue regeneration along with quantitative RT-PCR of collagen I and collagen III mRNA. Results: Presence of male ADMSCs was confirmed at Week 12. No statistically significant differences were found in the histochemical analysis; however, statistically significant differences between ADMSC and lesion group expression of collagen I and collagen III were evidenced, with 36.6% and 24.1% GAPDH-normalized mean expression, respectively, for collagen I (p < 0.05) and 26.3% and 11.9% GAPDH-normalized mean expression, respectively, for collagen III (p < 0.05). The expression ratio between the ADMSC and lesion group was 1.5 and 2.2 for collagen I and collagen III, respectively. Conclusion: Our results make an important contribution to the understanding and effect of ADMSCs in Achilles-tendon rupture.

10.
Microb Ecol ; 83(1): 18-33, 2022 Jan.
Article in English | MEDLINE | ID: mdl-33745062

ABSTRACT

Large baleen and toothed whales play crucial ecological roles in oceans; nonetheless, very little is known about their intestinal microbiomes. Based on striking differences in natural history and thus in feeding behaviours, it can be expected that intestinal microbiomes of large baleen whales and toothed whales are different. To test this hypothesis, the phylogenetic composition of faecal microbiomes was investigated by a 16S rRNA gene amplicon sequence-based approach for Bacteria and Archaea. Faecal samples from free-ranging large whales collected off the Azores Archipelago (Portugal) were used, comprising 13 individual baleen whales (one sei, two blue and ten fin whales) and four sperm whales. The phylogenetic composition of the Bacteria faecal microbiomes of baleen and toothed whales showed no significant differences at the phylum level. However, significant differences were detected at the family and genus levels. Most abundant phyla were Firmicutes, Bacteroidetes, Proteobacteria, Tenericutes and Spirochaeta. Few highly abundant bacterial genera were identified as key taxa with a high contribution to differences among baleen and toothed whales microbiomes. Only few archaeal sequences were detected, primarily Methanomassiliicoccales representing potential methanogenic Archaea. This is the first study that directly compares the faecal bacterial and archaeal microbiomes of free-ranging baleen and toothed whales which represent the two parvorders of Cetacea which members are fully aquatic large mammals which were evolutionary split millions of years ago.


Subject(s)
Balaenoptera , Microbiota , Animals , Phylogeny , RNA, Ribosomal, 16S/genetics , Sperm Whale/microbiology
11.
Mol Ecol ; 31(4): 1216-1233, 2022 02.
Article in English | MEDLINE | ID: mdl-34878694

ABSTRACT

Understanding the molecular mechanisms that determine a species' life history is important for predicting their susceptibility to environmental change. While specialist species with a narrow niche breadth (NB) maximize their fitness in their optimum habitat, generalists with broad NB adapt to multiple environments. The main objective of this study was to identify general transcriptional patterns that would distinguish bacterial strains characterized by contrasted NBs along a salinity gradient. More specifically, we hypothesized that genes encoding fitness-related traits, such as biomass production, have a higher degree of transcriptional regulation in specialists than in generalists, because the fitness of specialists is more variable under environmental change. By contrast, we expected that generalists would exhibit enhanced transcriptional regulation of genes encoding traits that protect them against cellular damage. To test these hypotheses, we assessed the transcriptional regulation of fitness-related and adaptation-related genes of 11 bacterial strains in relation to their NB and stress exposure under changing salinity conditions. The results suggested that transcriptional regulation levels of fitness- and adaptation-related genes correlated with the NB and/or the stress exposure of the inspected strains. We further identified a shortlist of candidate stress marker genes that could be used in future studies to monitor the susceptibility of bacterial populations or communities to environmental changes.


Subject(s)
Ecosystem , Salinity , Acclimatization , Adaptation, Physiological , Bacteria/genetics
12.
Syst Appl Microbiol ; 43(5): 126123, 2020 Sep.
Article in English | MEDLINE | ID: mdl-32847789

ABSTRACT

The aim of the study was to characterise the diversity and niche-specific colonization of Vibrio spp. in a marine aquaria system by a cultivation-dependent approach. A total of 53 Vibrio spp. isolates were cultured from different ecological niches in a marine aquarium including microplastic (MP) and sandy sediment particles (12 weeks after added sterile to the system), detritus, and the surrounding aquarium water. Based on the 16S rRNA gene sequence phylogeny and multilocus sequence analysis (MLSA) the isolates were assigned to seven different phylotypes. Six phylotypes were identified by high probability to the species level. The highest phylotype diversity was cultured from detritus and water (six out of seven phylotypes), while only two phylotypes were cultured from MP and sediment particles. Genomic fingerprinting indicated an even higher genetic diversity of Vibrio spp. at the strain (genotype) level. Again, the highest diversity of genotypes was recovered from detritus and water while only few partially particle-type specific genotypes were cultured from MP and sediment particles. Phylotype V-2 formed an independent branch in the MLSA tree and could not be assigned to a described Vibrio species. Isolates of this phylotype showed highest 16S rRNA gene sequence similarity to type strains of Vibrio japonicus (98.5%) and Vibrio caribbeanicus (98.4%). A representative isolate, strain THAF100T, was characterised by a polyphasic taxonomic approach and Vibrio aquimaris sp. nov., with strain THAF100T (=DSM 109633T=LMG 31434T=CIP 111709T) as type strain, is proposed as novel species.


Subject(s)
Ecosystem , Seawater/microbiology , Vibrio/classification , Vibrio/physiology , Animals , Aquatic Organisms/microbiology , Bacterial Typing Techniques , Biodiversity , Genes, Bacterial , Genes, rRNA , Genetic Variation , Genome, Bacterial , Genotype , Geologic Sediments/microbiology , Multilocus Sequence Typing , Phylogeny , RNA, Ribosomal, 16S/genetics , Sequence Analysis, DNA , Vibrio/genetics , Vibrio/isolation & purification , Virulence/genetics
13.
Front Microbiol ; 11: 597653, 2020.
Article in English | MEDLINE | ID: mdl-33584565

ABSTRACT

Experimental reproducibility in aquatic microbial ecology is critical to predict the dynamics of microbial communities. However, controlling the initial composition of naturally occurring microbial communities that will be used as the inoculum in experimental setups is challenging, because a proper method for the preservation of those communities is lacking. To provide a feasible method for preservation and resuscitation of natural aquatic prokaryote assemblages, we developed a cryopreservation procedure applied to natural aquatic prokaryotic communities. We studied the impact of inoculum size, processing time, and storage time on the success of resuscitation. We further assessed the effect of different growth media supplemented with dissolved organic matter (DOM) prepared from naturally occurring microorganisms on the recovery of the initially cryopreserved communities obtained from two sites that have contrasting trophic status and environmental heterogeneity. Our results demonstrated that the variability of the resuscitation process among replicates decreased with increasing inoculum size. The degree of similarity between initial and resuscitated communities was influenced by both the growth medium and origin of the community. We further demonstrated that depending on the inoculum source, 45-72% of the abundant species in the initially natural microbial communities could be detected as viable cells after cryopreservation. Processing time and long-term storage up to 12 months did not significantly influence the community composition after resuscitation. However, based on our results, we recommend keeping handling time to a minimum and ensure identical incubation conditions for repeated resuscitations from cryo-preserved aliquots at different time points. Given our results, we recommend cryopreservation as a promising tool to advance experimental research in the field of microbial ecology.

14.
Acta biol. colomb ; 24(1): 150-162, ene.-abr. 2019. tab, graf
Article in English | LILACS | ID: biblio-989047

ABSTRACT

ABSTRACT Many sessile marine invertebrates have life cycles involving the development of larvae that settle on specific substrates to initiate metamorphosis to juvenile forms. Although is recognized that bacterial biofilms play a role in this process, the responsible chemical cues are beginning to be investigated. Here, we tested the role of substrate-specific bacteria biofilms and their Quorum Sensing Signaling Molecule (QSSM) extracts on chemotaxis and settlement of larvae from Hydractinia symbiolongicarpus, a hydroid that grows on gastropod shells occupied by hermit crabs. We isolated and taxonomically identified by 16S rDNA sequencing, 14 bacterial strains from shells having H. symbiolongicarpus. Three isolates, Shigella flexneri, Microbacterium liquefaciens, and Kocuria erythromyxa, were identified to produce QSSMs using biosensors detecting N-acyl-L-homoserine lactones. Multispecies biofilms and QSSM extracts from these bacteria showed a positive chemotactic effect on H. symbiolongicarpus larvae, a phenomenon not observed with mutant strains of E. coli and Chromobacterium violaceum that are unable to produce QSSMs. These biofilms and QSSMs extracts induced high rates of larval attachment, although only 1 % of the attached larvae metamorphosed to primary polyps, in contrast to 99 % of larvae incubated with CsCl, an artificial inductor of attachment and metamorphosis. These observations suggest that bacterial QSSMs participate in H. symbiolongicarpus substrate selection by inducing larval chemotaxis and attachment. Furthermore, they support the notion that settlement in cnidarians is decoupled into two processes, attachment to the substrate and metamorphosis to a primary polyp, where QSSMs likely participate in the former but not in the latter.


RESUMEN Muchos invertebrados marinos sésiles tienen ciclos de vida que involucran el desarrollo de larvas que se asientan en sustratos específicos iniciando su metamorfosis a formas juveniles. Aunque es conocido que biopelículas bacterianas participan en este proceso, las señales químicas responsables hasta ahora se empiezan a investigar. Aquí evaluamos el papel de biofilms bacterianos y sus extractos de moléculas de señalización de "Quorum Sensing' (QSSM) sobre la quimiotaxis y el asentamiento larvario en Hydractinia symbiolongicarpus, un hidrozoario que crece sobre conchas de gastrópodos ocupadas por cangrejos ermitaños. Nosotros aislamos e identificamos taxonómicamente por secuenciación de rDNA 16S 14 cepas bacterianas de conchas con H. symbiolongicarpus. Tres de ellas, Shigella flexneri, Microbacterium liquefaciens, and Kocuria erythromyxa, mostraron producción de QSSMs usando biosensores que detectan N-acil-L-homoserin lactonas. Biopelículas y extractos de QSSMs de estas bacterias mostraron efectos quimiotácticos sobre larvas de H. symbiolongicarpus, efecto no observado en ensayos con cepas mutantes de E. coli y Chromobacterium violaceum que son incapaces de producir QSSMs. Las biopelículas y sus extractos indujeron adhesión larvaria sobre superficies, aunque solamente el 1 % de las larvas asentadas hicieron metamorfosis hacia pólipo primario, en contraste con 99 % de larvas incubadas con CsCl, un inductor artificial de asentamiento y metamorfosis. Estas observaciones sugieren que QSSMs de biopelículas bacterianas participan en la selección de sustrato de H. symbiolongicarpus, induciendo quimiotaxis y asentamiento de sus larvas. También sugieren que el asentamiento en cnidarios tiene dos procesos, adhesión y metamorfosis, donde las QSSMs participarían en el primero, pero no en el segundo.

15.
Foot Ankle Int ; 39(8): 942-948, 2018 08.
Article in English | MEDLINE | ID: mdl-29641262

ABSTRACT

BACKGROUND: Brachymetatarsia is a rare foot deformity caused by the premature closure of the metatarsal physis. It may result in functional as well as cosmetic alterations, which may require operative management. METHODS: A prospective study examining outcomes of 48 cases of brachymetatarsia with gradual bone lengthening at a rate of 1 mm/d using an external fixator and metatarsophalangeal joint fixation was performed. The difference between the length before treatment and after external fixator removal was measured. The patients were assessed at 2, 4, 6, and 8 weeks postoperatively; at the end of the period of distraction; and 1 year after surgery. The total number of patients was 26, and surgery was performed in 48 metatarsals. The mean age was 17.0 ± 4.1 (range, 11-24) years, and all were female. RESULTS: The fourth metatarsal was the most frequently affected, representing 98% of the cases; the third metatarsal represented the other 2%. The average length gained was 18.6 ± 6.7 mm, and the average length gained as a proportion of the original metatarsal length was 38.2% ± 3.1% (range, 13%-24%). The mean healing time was 71.0 (range, 64-104) days, and the mean healing index (healing time divided by centimeters of length gained [d/cm]) was 38.4 (range, 38.2-50.1) d/cm. CONCLUSION: Gradual bone lengthening at a rate of 1 mm/d using an external fixator and intramedullary nailing was a safe and efficient method, representing a minimally invasive procedure with a low incidence of complications and satisfactory results for the patient. LEVEL OF EVIDENCE: Level IV, retrospective case series.


Subject(s)
External Fixators , Foot Deformities, Congenital/surgery , Metatarsophalangeal Joint/surgery , Osteogenesis, Distraction/instrumentation , Toes/abnormalities , Adolescent , Bone Wires , Child , Female , Humans , Osteogenesis, Distraction/methods , Prospective Studies , Toes/surgery , Young Adult
16.
Int J Syst Evol Microbiol ; 68(5): 1689-1696, 2018 May.
Article in English | MEDLINE | ID: mdl-29620493

ABSTRACT

A novel Gram-stain-negative, rod-shaped, strictly aerobic, and orange-yellow pigmented bacterium, designated strain AFPH31T, was isolated from internal tissues of the scleractinian coral Pocillopora damicornis, cultured in a marine aquarium system at the Justus Liebig University Giessen, Germany. Phylogenetic analyses based on 16S rRNA gene sequences placed the strain within the monophyletic cluster of the genus Winogradskyella and showed highest sequence similarity to type strains of the species Winogradskyella eximia (96.6 %), Winogradskyella wandonensis (96.4 %), and Winogradskyella damuponensis (96.4 %). The strain grew well at 15-37 °C (optimum 25 °C), in the presence of 0.5-8.5 % NaCl (optimum 2 %), and at pH 5.5-8.5 (optimum pH 6.0-7.5). The major cellular fatty acids of strain AFPH31T were iso-C15 : 0 (22.0 %), iso-C15 : 1 G (16.9 %), iso-C17 : 0 3-OH (14.9 %), and anteiso-C15 : 0 (11.9 %). The major compound in the polyamine pattern was sym-homospermidine. The quinone system contained predominantly menaquinone MK-6. The polar lipid profile contained predominantly phosphatidylethanolamine, one unidentified aminolipid, and two unidentified lipids lacking a functional group. The genomic DNA G+C content was 36.8 mol%. According to the phylogenetic, chemotaxonomic, and phenotypic analyses we propose a novel species of the genus Winogradskyella named Winogradskyella pocilloporae sp. nov. The type strain is AFPH31T (=CCM 8816T=CIP 111546T).


Subject(s)
Anthozoa/microbiology , Flavobacteriaceae/classification , Phylogeny , Animals , Bacterial Typing Techniques , Base Composition , DNA, Bacterial/genetics , Fatty Acids/chemistry , Flavobacteriaceae/genetics , Flavobacteriaceae/isolation & purification , Germany , Phosphatidylethanolamines/chemistry , Pigmentation , RNA, Ribosomal, 16S/genetics , Sequence Analysis, DNA , Spermidine/analogs & derivatives , Spermidine/chemistry , Vitamin K 2/analogs & derivatives , Vitamin K 2/chemistry
17.
Environ Microbiol Rep ; 8(5): 851-864, 2016 Oct.
Article in English | MEDLINE | ID: mdl-27487247

ABSTRACT

We report the seasonal and single-diurnal variability of potentially active members of the prokaryote community in coastal surface waters off central Chile and the relationship between nitrifiers and solar radiation by combining 16S cDNA-based pyrosequencing, RT-qPCR of specific gene markers for nitrifiers (amoA, for general AOA, AOA-A, AOA-B, Nitrosopumilus maritimus and beta-AOB; and 16S rRNA gene for Nitrospina-like NOB), and solar irradiance measurements. We also evaluated the effects of artificial UVA-PAR and PAR spectra on nitrifiers by RT-qPCR. All nitrifiers (except AOA-B ecotype) were detected via RT-qPCR but AOA was the only group detected by pyrosequencing. Results showed high variability in their transcriptional levels during the day which could be associated to sunlight intensity thresholds in winter although AOA and Nitrospina-like NOB transcript number were also potentially related with environmental substrate availability. Only N. maritimus amoA transcripts showed a significant negative correlation with solar irradiances in both periods. During spring-summer, Nitrospina transcripts decreased at higher sunlight intensities, whereas the opposite was found during winter under natural (in situ) and artificial light experiments. In summary, a nitrifying community with variable tolerance to solar radiation is responsible for daily nitrification, and was particularly diverse during winter in the study area.

18.
PLoS One ; 9(6): e100224, 2014.
Article in English | MEDLINE | ID: mdl-24968138

ABSTRACT

We investigated the production of ammonium by the photodegradation of dissolved organic matter (DOM) in the coastal upwelling system off central Chile (36°S). The mean penetration of solar radiation (Z1%) between April 2011 and February 2012 was 9.4 m, 4.4 m and 3.2 m for Photosynthetically Active Radiation (PAR; 400-700 nm), UV-A (320-400 nm) and UV-B (280-320 nm), respectively. Ammonium photoproduction experiments were carried out using exudates of DOM obtained from cultured diatom species (Chaetoceros muelleri and Thalassiosira minuscule) as well as natural marine DOM. Diatom exudates showed net photoproduction of ammonium under exposure to UVR with a mean rate of 0.56±0.4 µmol L(-1) h(-1) and a maximum rate of 1.49 µmol L(-1) h(-1). Results from natural marine DOM showed net photoproduction of ammonium under exposure to PAR+UVR ranging between 0.06 and 0.2 µmol L(-1) h(-1). We estimated the potential contribution of photochemical ammonium production for phytoplankton ammonium demand. Photoammonification of diatom exudates could support between 117 and 453% of spring-summer NH4(+) assimilation, while rates obtained from natural samples could contribute to 50-178% of spring-summer phytoplankton NH4(+) requirements. These results have implications for local N budgets, as photochemical ammonium production can occur year-round in the first meters of the euphotic zone that are impacted by full sunlight.


Subject(s)
Ammonium Compounds/metabolism , Organic Chemicals/chemistry , Organic Chemicals/metabolism , Photolysis/radiation effects , Phytoplankton/metabolism , Seawater/chemistry , Chile , Diatoms/metabolism , Photosynthesis/radiation effects , Ultraviolet Rays
19.
P R Health Sci J ; 32(3): 113-23, 2013 Sep.
Article in English | MEDLINE | ID: mdl-24133892

ABSTRACT

Medicine's cardinal diagnostic and therapeutic resource is the clinical encounter. Over the last two centuries and particularly over the last five decades the function of the clinical encounter has been eroded to the point of near irrelevance because of the atomized and atomizing influence of technology and microspecialization. Meanwhile, over the past five decades the exceptionalist view of Homo sapiens inherent in the social and religious traditions of the West has similarly undergone radical changes. H. sapiens is now best understood as a microecosystem integrated into a much broader ecosystem: the biosphere. That human microecosystem is composed of constituents derived from the archaeal, bacterial, and eukaryan domains via endosymbiotic, commensalistic and mutualistic interactions. This amalgamation of 100 trillion cells and viral elements is regulated by a composite genome aggregated over the 3.8 billion years of evolutionary history of organic life. No component of H. sapiens or its genome can be identified as irreducibly and exclusively human. H. sapiens' humanity is an emergent property of the microecosystem. Ironically as H. sapiens is viewed by evolutionary science in a highly integrated manner medicine approaches it as a balkanized, deaggregated entity through the eye of 150 different specialties. To effectively address the needs of H sapiens in its role as patient by the same species in its role as physician the disparate views must be harmonized. Here I review some conceptual elements that would assist a physician in addressing the needs of the patient in integrum, as a microecosystem, by the former address the latter as a historical gestalt being. The optimal way to recover the harmony between patient and physician is through a revitalization of the clinical encounter via an ecological and Darwinian epistemology.


Subject(s)
Human Characteristics , Medicine , Patients , Physicians , Animals , Archaea/physiology , Bacterial Physiological Phenomena , Biological Evolution , Causality , Cultural Evolution , Endogenous Retroviruses/genetics , Genome, Human , Humans/genetics , Humans/microbiology , Humans/psychology , Humans/virology , Medicine/trends , Microbial Consortia , Microbiota , Models, Biological , Patients/psychology , Physician-Patient Relations , Physicians/psychology , Primates/classification , Primates/genetics , Professional Practice , Species Specificity , Symbiosis
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