Coleoptera and microbe biomass in Antarctic Dry Valley paleosols adjacent to the Inland Ice: Implications for Mars

Bulk paleosol samples collected from a Middle to Early Miocene moraine in the New Mountain area of the Dry Valleys, Antarctica, yielded Coleoptera exoskeletons and occasional endoskeletons showing considerable diagenetic effects along with several species of bacteria, all lodged in a dry-frozen but salt-rich horizon at shallow depth to the land surface. The till is at the older end of a chronologic sequence of glacial deposits, thought to have been deposited before the transition from wet-based to cold-based ice (similar to 15 Ma), and hence, entirely weathered in contact with the subaerial atmosphere. It is possible, though not absolutely verifiable, that the skeletons date from this early stage of emplacement having undergone modifications whenever light snowmelt occurred or salt concentrations lowered the freezing temperature to maintain water as liquid. Correlation of the Coleoptera species with cultured bacteria in the sample and the likelihood of co-habitation with Beauveria bassiani found in two adjacent, although younger paleosols, leads to new questions about the antiquity of the Coleoptera and the source of N and glucose from chitinase derived from the insects. The skeletons in the 831 section may date close to the oldest preserved chitin (Oligocene) yet found on Earth. While harsh Martian conditions make it seemingly intolerable for complex, multicellular organisms such as insects to exist in the near-surface and subaerially, life within similar cold, dry paleosol microenvironments (Cryosols) of Antarctica point to life potential for the Red Planet, especially when considering the relatively diverse microbe (bacteria and fungi) population. (C) 2011 Elsevier Ltd. All rights reserved.

Weathering rinds as mirror images of palaeosols: Examples from the Western Alps with correlation to Antarctica and Mars

Weathering rinds have been used for decades as relative age indicators to differentiate glacial deposits in long Quaternary sequences, but only recently has it been shown that rinds contain long and extensive palaeoenvironmental records that often extend far beyond mere repositories of chemical weathering on both Earth and Mars. When compared with associated palaeosols in deposits of the same age, rinds often carry a zonal weathering record that can be correlated with palaeosol horizon characteristics, with respect to both abiotic and biotic parameters. As demonstrated with examples from the French and Italian Alps, rinds in coarse clastic sediment contain weathering zones that correlate closely with horizon development in associated palaeosols of presumed Late Glacial age. In addition to weathering histories in both rinds and palaeosols, considerable evidence exists to indicate that the black mat impact (12.8 ka) reached the European Alps, a connection with the Younger Dryas readvance supported by both mineral and chemical composition. Preliminary metagenomic microbial analysis using density gradient gel electrophoresis suggests that the eubacterial microbial population found in at least one Ah palaeosol horizon associated with a rind impact site is different from that in other Late Glacial and Younger Dryas surface palaeosol horizons. © 2013 The Geological Society of London.

Investigation of the impact of feeding Lactobacillus plantarum CRL 1815 encapsulated in microbially derived polymers on the rat faecal microbiota

AIMS: The aim of this study was to evaluate the impact of the administration of microencapsulated Lactobacillus plantarum CRL 1815 with two combinations of microbially derived polysaccharides, xanthan : gellan gum (1%:0·75%) and jamilan : gellan gum (1%:1%), on the rat faecal microbiota. METHODS AND RESULTS: A 10-day feeding study was performed for each polymer combination in groups of 16 rats fed either with placebo capsules, free or encapsulated Lact. plantarum or water. The composition of the faecal microbiota was analysed by fluorescence in situ hybridization and temporal temperature gradient gel electrophoresis. Degradation of placebo capsules was detected, with increased levels of polysaccharide-degrading bacteria. Xanthan : gellan gum capsules were shown to reduce the Bifidobacterium population and increase the Clostridium histolyticum group levels, but not jamilan : gellan gum capsules. Only after administration of jamilan : gellan gum-probiotic capsules was detected a significant increase in Lactobacillus-Enterococcus group levels compared to controls (capsules and probiotic) as well as two bands were identified as Lact. plantarum in two profiles of ileum samples. CONCLUSIONS: Exopolysaccharides constitute an interesting approach for colon-targeted delivery of probiotics, where jamilan : gellan gum capsules present better biocompatibility and promising results as a probiotic carrier. SIGNIFICANCE AND IMPACT OF STUDY: This study introduces and highlights the importance of biological compatibility in the encapsulating material election, as they can modulate the gut microbiota by themselves, and the use of bacterial exopolysaccharides as a powerful source of new targeted-delivery coating material.

Efficacité d'espèces ligneuses en symbiose mycorhizienne arbusculaire pour la phytoremédiation d'un site urbain contaminé

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Estabilitat conformacional de variants de la ribonucleasa A: pressió i temperatura com a inductors dels desplegament proteic

A fi d'analitzar la contribució de la regió C-terminal proposada com a iniciadora del plegament (CFIS 106-118) a l'estabilitat de l'RNasa A, els residus alifàtics d'aquesta regió es van substituir, mitjançant mutagènesi dirigida, per altres residus en els quals la cadena lateral alifàtica era rogressivament escurçada. La major part de les substitucions projectades suposaven delecions no disruptives de grups metil(è). A més, es va reemplaçar la Tyr115 per un Trp, de manera que, potencialment, s'introduïa una única sonda fluorescent, no desestabilitzant, per tal de seguir els canvis conformacionals que es poguessin generar en la regió durant el procés de legament/desplegament de la proteïna. Tant els paràmetres cinètics, com els espectres d'FTIR i CD, determinats per cadascuna de les ribonucleases variants, indiquen que els reemplaçaments aminoacídics efectuats presenten, en general, poc o cap efecte en l'estructura nativa i en l'activitat de l'enzim. Es va emprar l'espectroscòpia d'absorció a l'ultraviolat de quarta derivada, la fluorescència (per la variant amb Trp) i l'espectroscòpia d'infraroig per transformada de Fourier, per tal de seguir i caracteritzar, en condicions d'equilibri, les transicions conformacionals de cada variant en funció de la pressió i de la temperatura. Els resultats es van comparar amb els que es van obtenir per la proteïna salvatge. Per determinar més a fons les característiques del procés de desplegament de la variant Y115W, les transicions de desnaturalització induïdes per urea d'aquesta variant i de la proteïna salvatge, van ésser examinades per mitjà d'electroforesi en gradient d'urea i espectroscòpia de fluorescència. Curiosament, els canvis conformacionals que resulten de la desnaturalització per pressió són molt semblants als que s'obtenen per temperatura. Enfront d'un augment gradual tant de pressió com de temperatura, l'estructura terciària i els elements d'estructura secundària de les proteïnes estudiades es perden de manera conjunta i reversible. Aquestes variacions estructurals que es promouen descriuen un procés de desplegament molt cooperatiu i en dos estats. Atès que ambdues tècniques (UV i FTIR) utilitzen cadascuna un règim de concentració proteica molt diferent, els resultats indiquen que el procés de desplegament per pressió i per temperatura és intramolecular. Els resultats obtinguts suggereixen que la hidrofobicitat i el volum de les cadenes laterals del CFIS, juntament amb les interaccions de van der Waals entre elements d'estructura secundària intervenen de manera molt notable en l'estabilització de la proteïna. Entre els diferents aminoàcids alifàtics que pertanyen al CFIS C-terminal, la Val108 és el residu més important per tal de preservar la integritat estructural de l'estat natiu. Els reemplaçaments en aquesta posició causen petites alteracions conformacionals i una gran desestabilització de la proteïna (per exemple, el punt mig de la transició de desnaturalització per pressió i per temperatura de la variant V108G disminueix uns 592 MPa i 25ºC, respectivament, respecte a la proteïna salvatge). D'acord amb els resultats obtinguts, la variant Y115W ofereix una sonda útil per tal de seguir la cinètica de plegament/desplegament de l'RNasa A.

Rifaximin modulates the colonic microbiota of patients with Crohn's disease: an in vitro approach using a continuous culture colonic model system.

Rifaximin, a rifamycin derivative, has been reported to induce clinical remission of active Crohn's disease (CD), a chronic inflammatory bowel disorder. In order to understand how rifaximin affects the colonic microbiota and its metabolism, an in vitro human colonic model system was used in this study. We investigated the impact of the administration of 1800 mg/day of rifaximin on the faecal microbiota of four patients affected by colonic active CD [Crohn's disease activity index (CDAI > 200)] using a continuous culture colonic model system. We studied the effect of rifaximin on the human gut microbiota using fluorescence in situ hybridization, quantitative PCR and PCR–denaturing gradient gel electrophoresis. Furthermore, we investigated the effect of the antibiotic on microbial metabolic profiles, using 1H-NMR and solid phase microextraction coupled with gas chromatography/mass spectrometry, and its potential genotoxicity and cytotoxicity, using Comet and growth curve assays. Rifaximin did not affect the overall composition of the gut microbiota, whereas it caused an increase in concentration of Bifidobacterium, Atopobium and Faecalibacterium prausnitzii. A shift in microbial metabolism was observed, as shown by increases in short-chain fatty acids, propanol, decanol, nonanone and aromatic organic compounds, and decreases in ethanol, methanol and glutamate. No genotoxicity or cytotoxicity was attributed to rifaximin, and conversely rifaximin was shown to have a chemopreventive role by protecting against hydrogen peroxide-induced DNA damage. We demonstrated that rifaximin, while not altering the overall structure of the human colonic microbiota, increased bifidobacteria and led to variation of metabolic profiles associated with potential beneficial effects on the host.

Investigation of the impact of feeding Lactobacillus plantarum CRL 1815 encapsulated in microbially derived polymers on the rat faecal microbiota

AIMS: The aim of this study was to evaluate the impact of the administration of microencapsulated Lactobacillus plantarum CRL 1815 with two combinations of microbially derived polysaccharides, xanthan : gellan gum (1%:0·75%) and jamilan : gellan gum (1%:1%), on the rat faecal microbiota. METHODS AND RESULTS: A 10-day feeding study was performed for each polymer combination in groups of 16 rats fed either with placebo capsules, free or encapsulated Lact. plantarum or water. The composition of the faecal microbiota was analysed by fluorescence in situ hybridization and temporal temperature gradient gel electrophoresis. Degradation of placebo capsules was detected, with increased levels of polysaccharide-degrading bacteria. Xanthan : gellan gum capsules were shown to reduce the Bifidobacterium population and increase the Clostridium histolyticum group levels, but not jamilan : gellan gum capsules. Only after administration of jamilan : gellan gum-probiotic capsules was detected a significant increase in Lactobacillus-Enterococcus group levels compared to controls (capsules and probiotic) as well as two bands were identified as Lact. plantarum in two profiles of ileum samples. CONCLUSIONS: Exopolysaccharides constitute an interesting approach for colon-targeted delivery of probiotics, where jamilan : gellan gum capsules present better biocompatibility and promising results as a probiotic carrier. SIGNIFICANCE AND IMPACT OF STUDY: This study introduces and highlights the importance of biological compatibility in the encapsulating material election, as they can modulate the gut microbiota by themselves, and the use of bacterial exopolysaccharides as a powerful source of new targeted-delivery coating material.

Investigation of the Europium Emission Spectra of the Europium-Oxytetracycline Complex in the Presence of Human Low-Density Lipoproteins

Low-Density Lipoprotein (LDL), often known as ""bad cholesterol"" is one of the responsible to increase the risk of coronary arterial diseases. For this reason, the cholesterol present in the LDL particle has become one of the main parameters to be quantified in routine clinical diagnosis. A number of tools are available to assess LDL particles and estimate the cholesterol concentration in the blood. The most common methods to quantify the LDL in the plasma are the density gradient ultracentrifugation and nuclear magnetic resonance (NMR). However, these techniques require special equipments and can take a long time to provide the results. In this paper, we report on the increase of the Europium emission in Europium-oxytetracycline complex aqueous solutions in the presence of LDL. This increase is proportional to the LDL concentration in the solution. This phenomenum can be used to develop a method to quantify the number of LDL particles in a sample. A comparison between the performances of the oxytetracycline and the tetracycline in the complexes is also made.

Epichlorohydrin Cross-Linking of Synthetic DNA Oligomers

Epichlorohydrin (ECH), an important chemical in the synthetic polymer industry, is a bifunctional alkylating agent with the potential to form DNA interstrand crosslinks. Occupational exposure to this suspect carcinogen leads to chromosomal aberrations, and ECH has been shown to undergo reaction with DNA in vivo and in vitro. We are using denaturing polyacrylamide gel electrophoresis to assess cross-linking of synthetic DNA oligomers by both ECH and the related compound, epibromohydrin (EBH). Both epihalohydrins produce a low-mobility band on denaturing gels consistent with an interstrand cross-link. Moreover, the efficiencies, sequence preferences, reaction kinetics, and pH dependence differ for the two compounds, suggesting different mechanisms of reaction. Understanding these alkylation reactions may help explain the role of the epihalohydrins in cancer development.

Esterase enzymes involved in pyrethroid and organophosphate resistance in a Brazilian population of Riphicephallus (Boophilus) microplus (Acari, Ixodidae)

Esterases are a group of enzymes that are reportedly associated with acaricide resistance in Riphicephallus (Boophilus) microplus. A comparative analysis was made of the esterase patterns in malathion and deltamethrin-sensitive, tolerant and resistant tick groups, using non-denaturing polyacrylamide gel electrophoresis. Electrophoretical profiles revealed four bands of esterase activity against alpha-naphthyl acetate; which were dubbed EST-1 to EST-4. The EST-3 and EST-4 were detected in all strains and were classified as carboxylesterases (CaEs). The EST-2, classified as an acetylcholinesterase (AChE), was detected in all groups, but its staining intensity increased from susceptible to resistant groups, indicating an altered production according to the degree of resistance. EST-1, which was also classified as an AChE, was detected exclusively in tolerant and resistant groups to both acaricides, but displayed greater activity in the malathion-resistant group. These data suggest that these AChEs may represent an important detoxification strategy developed to overcome the effects of acaricides. (C) 2008 Elsevier B.V. All rights reserved.

Spatial and Temporal Variation of Archaeal, Bacterial and Fungal Communities in Agricultural Soils

Background: Soil microbial communities are in constant change at many different temporal and spatial scales. However, the importance of these changes to the turnover of the soil microbial communities has been rarely studied simultaneously in space and time. Methodology/Principal Findings: In this study, we explored the temporal and spatial responses of soil bacterial, archaeal and fungal beta-diversities to abiotic parameters. Taking into account data from a 3-year sampling period, we analyzed the abundances and community structures of Archaea, Bacteria and Fungi along with key soil chemical parameters. We questioned how these abiotic variables influence the turnover of bacterial, archaeal and fungal communities and how they impact the long-term patterns of changes of the aforementioned soil communities. Interestingly, we found that the bacterial and fungal b-diversities are quite stable over time, whereas archaeal diversity showed significantly higher fluctuations. These fluctuations were reflected in temporal turnover caused by soil management through addition of N-fertilizers. Conclusions: Our study showed that management practices applied to agricultural soils might not significantly affect the bacterial and fungal communities, but cause slow and long-term changes in the abundance and structure of the archaeal community. Moreover, the results suggest that, to different extents, abiotic and biotic factors determine the community assembly of archaeal, bacterial and fungal communities.

EX-SITU BIOREMEDIATION OF BRAZILIAN SOIL CONTAMINATED WITH PLASTICIZERS PROCESS WASTES

The aim of this research was to evaluate the bioremediation of a soil contaminated with wastes from a plasticizers industry, located in Sao Paulo, Brazil. A 100-kg soil sample containing alcohols, adipates and phthalates was treated in an aerobic slurry-phase reactor using indigenous and acclimated microorganisms from the sludge of a wastewater treatment plant of the plasticizers industry (11gVSS kg(-1) dry soil), during 120 days. The soil pH and temperature were not corrected during bioremediation; soil humidity was corrected weekly to maintain 40%. The biodegradation of the pollutants followed first-order kinetics; the removal efficiencies were above 61% and, among the analyzed plasticizers, adipate was removed to below the detection limit. Biological molecular analysis during bioremediation revealed a significant change in the dominant populations initially present in the reactor.

Physical-chemical and microbiological changes in Cerrado Soil under differing sugarcane harvest management systems

Background: Sugarcane cultivation plays an important role in Brazilian economy, and it is expanding fast, mainly due to the increasing demand for ethanol production. In order to understand the impact of sugarcane cultivation and management, we studied sugarcane under different management regimes (pre-harvest burn and mechanical, unburnt harvest, or green cane), next to a control treatment with native vegetation. The soil bacterial community structure (including an evaluation of the diversity of the ammonia oxidizing (amoA) and denitrifying (nirK) genes), greenhouse gas flow and several soil physicochemical properties were evaluated. Results: Our results indicate that sugarcane cultivation in this region resulted in changes in several soil properties. Moreover, such changes are reflected in the soil microbiota. No significant influence of soil management on greenhouse gas fluxes was found. However, we did find a relationship between the biological changes and the dynamics of soil nutrients. In particular, the burnt cane and green cane treatments had distinct modifications. There were significant differences in the structure of the total bacterial, the ammonia oxidizing and the denitrifying bacterial communities, being that these groups responded differently to the changes in the soil. A combination of physical and chemical factors was correlated to the changes in the structures of the total bacterial communities of the soil. The changes in the structures of the functional groups follow a different pattern than the physicochemical variables. The latter might indicate a strong influence of interactions among different bacterial groups in the N cycle, emphasizing the importance of biological factors in the structuring of these communities. Conclusion: Sugarcane land use significantly impacted the structure of total selected soil bacterial communities and ammonia oxidizing and denitrifier gene diversities in a Cerrado field site in Central Brazil. A high impact of land use was observed in soil under the common burnt cane management. The green cane soil also presented different profiles compared to the control soil, but to at a lesser degree.

Circulating oxidized low-density lipoprotein (LDL) is associated with risk factors of the metabolic syndrome and LDL size in clinically healthy 58-year-old men (AIR study).

OBJECTIVES Hypothetically the atherogenic effect of the metabolic syndrome may be mediated through the increased occurrence of small LDL-particles which are easily modified to atherogenic oxidized LDL (ox-LDL). The aim of this study was to test this concept by examining the association between circulating ox-LDL, LDL-particle size, and the metabolic syndrome. DESIGN AND RESULTS A population-based sample of clinically healthy 58-year-old men (n = 391) was recruited. Ox-LDL was measured by ELISA (specific monoclonal antibody, mAb-4E6) and LDL-particle size by gradient gel electrophoresis. The results showed that ox-LDL significantly correlated to factors constituting the metabolic syndrome; triglycerides (r = 0.43), plasma insulin (r = 0.20), body mass index (r = 0.20), waist-to-hip ratio (r = 0.21) and HDL (r = -0.24); (P < 0.001). Ox-LDL correlated also to LDL-particle size (r = -0.42), Apo-B (r = 0.70), LDL (r = 0.65); (P < 0.001) and, furthermore, with Apo A-1 (r = -0.13) and heart rate (r = 0.13); (P < 0.01). CONCLUSION The metabolic syndrome was accompanied by high plasma ox-LDL concentrations compared with those without the syndrome. Ox-LDL levels were associated with most of the risk factors constituting the metabolic syndrome and was, in addition related to small LDL-particle size. To our knowledge the present study is the first one to demonstrate that circulating ox-LDL levels are associated with small LDL-particle size in a population representative sample of clinically healthy middle-aged men. The high degree of intercorrelation amongst several factors makes it difficult to clarify the independent role of any specific factor.

Molecular investigation of the microbial populations of the pink sugarcane mealybug, Saccharicoccus sacchari

In an attempt to better understand the microbial diversity and endosymbiotic microbiota of the pink sugarcane mealybug (PSMB) Saccharicoccus sacchari Cockerell (Homoptera: Pseudococcidae), culture-independent approaches, namely PCR, a 16S rDNA clone library, and temperature gradient gel electrophoresis (TGGE) were used. Previous work has indicated that the acetic acid bacteria Gluconacetobacter sacchari, Gluconacetobacter diazotrophicus, and Gluconacetobacter liquefaciens represent only a small proportion of the microbial community of the PSMB. These findings were supported in this study by TGGE, where no bands representing G. sacchari, G. diazotrophicus, and G. liquefaciens on the acrylamide gel could be observed following electrophoresis, and by a 16S rDNA clone library study, where no clones with the sequence of an acetic acid bacterium were found. Instead, TGGE revealed that the mealybug microbial community was dominated by beta- and gamma-Proteobacteria. The dominant band in TGGE gels found in a majority of the mealybug samples was most similar, according to BLAST analysis, to the beta-symbiont of the craw mealybug Antonina crawii and to Candidatus Tremblaya princeps, an endosymbiont from the mealybug Paracoccus nothofagicola. The sequences of other dominant bands were identified as gamma-Proteobacteria, and were most closely related to uncultured bacterial clones obtained from soil samples. Mealybugs collected from different areas in Queensland, Australia, were found to produce similar TGGE profiles, although there were a few exceptions. A 16S rDNA clone library based on DNA extracted from a mealybug collected from sugarcane in the Burdekin region in Queensland, Australia, indicated very low levels of diversity among mealybug microbial populations. All sequenced clones were most closely related to the same members of the gamma-Proteobacteria, according to BLAST analysis.