AIMS: Due to their antimicrobial activity, silver nanoparticles (Ag‐NPs) are being increasingly used in a number of industrial products. The accumulation of Ag‐NPs in the soil might affect plant ...growth‐promoting rhizobacteria and, in turn, the plants. We describe the effects of Ag‐NPs on the soil bacteria Azotobacter vinelandii and Bacillus subtilis. METHODS AND RESULTS: In growth‐inhibition studies, A. vinelandii showed extreme sensitivity to Ag‐NPs, compared to B. subtilis. We investigated the effects of Ag‐NPs at subinhibitory concentrations, both on planktonic and sessile B. subtilis cells. As determined by 2,7‐dichlorofluorescein‐diacetate assays, Ag‐NPs increase the formation of reactive oxygen species in planktonic cells, but not in sessile cells, suggesting the activation of scavenging systems in biofilms. Consistently, proteomic analysis in B. subtilis Ag‐NPs‐treated biofilms showed increased production of proteins related to quorum sensing and involved in stress responses and redox sensing. Extracellular polysaccharides production and inorganic phosphate solubilization were also increased, possibly as part of a coordinated response to stress. CONCLUSIONS: At low concentrations, Ag‐NPs killed A. vinelandii and affected cellular processes in planktonic and sessile B. subtilis cells. SIGNIFICANCE AND IMPACT OF THE STUDY: Re‐direction of gene expression, linked to selective toxicity, suggests a strong impact of Ag‐NPs on soil bacterial communities.
The molecular details of local plant response against Xanthomonas translucens infection is largely unknown. Moreover, there is no knowledge about effects of the pathogen on the root's transcriptome ...and proteome. Therefore, we investigated the global gene and protein expression changes both in leaves and roots of wheat (Triticum aestivum) 24 h post leaf infection of X. translucens. This simultaneous analysis allowed us to obtain insight into possible metabolic rearrangements in above- and belowground tissues and to identify common responses as well as specific alterations. At the site of infection, we observed the implication of various components of the recognition, signaling, and amplification mechanisms in plant response to the pathogen. Moreover, data indicate a massive down-regulation of photosynthesis and confirm the chloroplast as crucial signaling hub during pathogen attack. Notably, roots responded as well to foliar attack and their response significantly differed from that locally triggered in infected leaves. Data indicate that roots as a site of energy production and synthesis of various secondary metabolites may actively influence the composition and colonisation level of root-associated microbes. Finally, our results emphasize the accumulation of jasmonic acid, pipecolic acid and/or the downstream mediator of hydrogen peroxide as long distal signals from infected leaves to roots.
Ammonium and nitrite oxidizing biomasses (AOB and NOB) were investigated in parallel pilot plants: a membrane bioreactor (MBR) and a conventional activated sludge process (CASP) fed with domestic ...wastewater. The kinetics of AOB and NOB were monitored through titrimetric tests. The maximum specific growth rate of the AOB (µ
max,AOB
) was affected by the solids' retention time (SRT) maintained during the start up: by varying the start up SRT from 20 d to 8 d, µ
max,AOB
in the CASP varied from 0.45 d
−1
±0.04 to 0.72 d
−1
± 0.2 respectively; the mean value of µ
max,AOB
in the MBR samples (always maintained at SRT = 20 d) was in the range 0.45-0.49 d
−1
. The endogenous decay coefficients of the NOB and AOB and the maximum specific growth rates of the NOB were similar in both MBR and CASP. Inhibition tests with different concentrations of allylthiourea (ATU) were carried out on samples from both activated sludge systems: the MBR sludge exhibited higher sensitivity to a low ATU concentration; however, the maximum nitrification activity recovered more rapidly than the CASP sludge.
Cardiovascular disease (CVD) is the main cause of death in hemodialysis (HD) patients. Vascular calcification (VC) is common in these patients. The main objective of this study was to evaluate if a ...semiquantitative radiographic method is able to detect VC progression in a prospective cohort of patients and predict the risk of cardiovascular events. Secondarily, we intend to identify predictors of the presence and progression of VC.
49 patients undergoing HD for ≥ 90 days were included. At the beginning and after 12 months, the VC score (VCS) was determined by the Kauppila method, and clinical, nutritional, and laboratory markers were measured. The rates of fatal and nonfatal cardiovascular events were analyzed from months 13 to 24.
Of 49 patients, 55.1% were male, 46.9% diabetic, and the mean age was 59.5 ± 14.4 years. At the beginning of the follow-up, 65.3% of the patients exhibited VC with a median VCS of 4 points. The intracellular water was negatively associated with VC and its intensity. The presence of VC was the only independent predictor of VC progression. Among patients with VC, 17 showed rapid progression, and 15 showed slow progression. The VCS was independently associated with rapid progression, while ΔCS (final VCS - initial VCS) was an independent predictor of cardiovascular events.
The Kauppila method was able to detect VC, its progression, and predict cardiovascular events. These results suggest an association of VC with nutritional status.
Purpose
Malnutrition is a strong predictor of mortality in hemodialysis patients. Several scoring systems for evaluating nutritional status have been proposed. However, they rely on different sets of ...anthropometric and laboratory markers to make a diagnosis of malnutrition and assess its impact on prognosis. To validate them, nutritional scores should be compared with clinical outcomes. Thus, the purpose of this study was to assess malnutrition by three different nutrition scoring systems and determine which best predicts mortality in hemodialysis patients.
Methods
This prospective study included 106 adult chronic hemodialysis patients. Their mean age was 56.3 ± 14.9 years and mean body mass index 24.8 (21.8–28.9); 52 % were men and they had been on dialysis for 24 (5–55) months. Nutritional status was classified according to the diagnostic systems proposed by Wolfson et al. (Am J Clin Nutr 39(4):547–555,
1984
), International Society of Renal Nutrition and Metabolism (ISRNM) (Fouque et al. in Kidney Int 73(4):391–398,
2008
), and Beberashvili et al. (Nephrol Dial Transplant 25(8):2662–2671,
2010
). During about 2 years of follow-up, mortality was assessed by Kaplan–Meier curves, log-rank, and Cox’s models adjusted for diabetes, sex, C-reactive protein, time on dialysis, age, and fractional urea clearance.
Results
Twenty-three deaths (21.5 %) occurred during the study period. According to the systems of Wolfson, Beberashvili, and the ISRNM, 54, 32, and 20 % of patients, respectively, had malnutrition. Both univariate and multivariate analyses showed that the ISRNM system was the only one that predicted poorer survival (fourfold higher death risk) in malnourished patients.
Conclusions
The scoring system proposed by the ISRNM most accurately identifies patients at higher risk of death.
This paper reports the identification of bacterial endosymbionts that inhabit the cytoplasm of the marine ciliated protozoon Euplotes magnicirratus. Ultrastructural and full-cycle rRNA approaches ...were used to reveal the identity of these bacteria. Based on analysis of 16S rRNA gene sequences, evolutionary trees were constructed; these placed the endosymbiont in the genus Devosia in the alpha-Proteobacteria. The validity of this finding was also shown by fluorescence in situ hybridization with a Devosia-specific oligonucleotide probe. Differences at the 16S rRNA gene level (which allowed the construction of a species-specific oligonucleotide probe) and the peculiar habitat indicate that the endosymbiont represents a novel species. As its cultivation has not been successful to date, the provisional name 'Candidatus Devosia euplotis' is proposed. The species- and group-specific probes designed in this study could represent convenient tools for the detection of 'Candidatus Devosia euplotis' and Devosia-like bacteria in the environment.
Abstract
The correlation between environmental stress and DNA methylation has been studied by following the methylation status of cytosine residues in the DNA of pea root tips exposed to water ...deficit. DNA methylation was evaluated by two complementary approaches: (I) immunolabelling by means of a monoclonal antibody against 5-methylcytosine; (II) MSAP (Methylation-Sensitive Amplified Polymorphism) to verify if methylation and de-methylation in response to water deficit may be related to specific DNA sequences. Immunolabelling showed that water stress induces cytosine hypermethylation in the pea genome. Regarding the CCGG target sequence, an increase in methylation specifically in the second cytosine (about 40 % of total site investigated) was revealed by MSAP analyses. In addition, MSAP band profile detected in three independent repetitions was highly reproducible suggesting that, at least for the CCGG target sequence, methylation was addressed to specific DNA sequences.
Bacteria of the family Rickettsiaceae (order Rickettsiales, α-Proteobacteria) are mainly known to be endosymbionts of arthropods with the capability to infect also vertebrate cells. Recently, they ...have also been found as leech endocytobionts. In the present paper, we report the first finding of a bacterium belonging to the family Rickettsiaceae in a natural population of a marine ciliate protozoan, namely Diophrys appendiculata, collected in the Baltic Sea. Bacteria were unambiguously identified through morphological characterization and the "full-cycle rRNA approach" (i.e., 16S rRNA gene characterization and use of specifically designed oligonucleotide probes for in situ detection). Symbionts are rod-shaped bacteria that grow freely in the cytoplasm of the host cell. They present two different morphotypes, similar in size, but different in cytoplasmic density. These are typical morphological features of members of the family Rickettsiaceae. 16S rRNA gene sequence showed that Diophrys symbionts share a high similarity value (>92%) with bacteria belonging to the genus Rickettsia. Phylogenetic analysis revealed that these new endosymbionts are clearly included in the clade of the family Rickettsiaceae, but they occupy an independent phylogenetic position with respect to members of the genus Rickettsia. This is the first report of a member of this family from a host protozoan and from a marine habitat. This result shows that this bacterial group is more diversified and widespread than supposed so far, and that its ecological relevance could until now have been underestimated. In light of these considerations, the two 16S rRNA oligonucleotide probes here presented, specific for members of the Rickettsiaceae, can represent useful tools for further researches on the presence and the spread of these microorganisms in the natural environment.
Cr(III) and Cr(VI) exposition induces in germinating kiwifruit pollen a metabolic impairment due to a proteome alteration but not to a genotoxic effect.
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► Cr(III) and Cr(VI) do not ...induce DNA laddering in kiwifruit pollen at the doses used. ► Cr alters proteins involved in mitochondrial oxidative phosphorylation and the ATP content. ► Both Cr species affect the ubiquitin proteolytic pathway through different mechanisms.
The present study is aimed at identifying molecular changes elicited by Cr(III) and Cr(VI) on germinating kiwifruit pollen. To address this question, comparative proteomic and DNA laddering analyses were performed. While no genotoxic effect was detected, a number of proteins whose accumulation levels were altered by treatments were identified. In particular, the upregulation of some proteins involved in the scavenging response, cell redox homeostasis and lipid synthesis could be interpreted as an oxidative stress response induced by Cr treatment. The strong reduction of two proteins involved in mitochondrial oxidative phosphorylation and a decline in ATP levels were also observed. The decrease of pollen energy availability could be one of the causes of the severe inhibition of the pollen germination observed upon exposure to both Cr(III) and Cr(VI). Finally, proteomic and biochemical data indicate proteasome impairment: the consequential accumulation of misfolded/damaged proteins could be an important molecular mechanism of Cr(III) toxicity in pollen.
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