Drastic changes in aquatic bacterial populations from the Cuatro Cienegas Basin (Mexico) in response to long-term environmental stress

Understanding the changes of aquatic microbial community composition in response to changes in temperature and ultraviolet irradiation is relevant for predicting biogeochemical modifications in the functioning of natural microbial communities under global climate change scenarios. Herein we investigate shifts in the bacterioplankton composition in response to long-term changes in temperature and UV radiation. For this purpose, 15 mesocosms were seeded with composite aquatic microbial communities from natural pools within the Cuatro Cienegas Basin (Mexican Chihuahuan desert) and were subject to different temperatures and UV conditions. 16S rRNA gene clone libraries were obtained from water samples at the mid-point (4 months) and the end of the experiment (8 months). An increase in bacterial diversity over time was found in the treatment of constant temperature and UV protection, which suggests that stable environments promote the establishment of complex and diverse bacterial community. Drastic changes in the phylogenetic bacterioplankton composition and structure were observed in response to fluctuating temperature and increasing UV radiation and temperature. Fluctuating temperature induced the largest decrease of bacterial richness during the experiment, indicating that frequent temperature changes drive the reduction in abundance of several species, most notably autotrophs. The long-term impact of these environmental stresses reduced diversity and selected for generalist aquatic bacterial populations, such as Porphyrobacter. These changes at the community level occur at an ecological time scale, suggesting that under global warming scenarios cascade effects on the food web are possible if the microbial diversity is modified.     

Dentists’ Dietary Perception and Practice Patterns in a Dental Practice-Based Research Network

Background

Dental caries are largely preventable, and epidemiological evidence for a relationship between diet and oral health is abundant. To date, however, dentists’ perceptions about the role of diet and dentists’ practice patterns regarding diet counseling have not been clarified.

Objective

The purposes of this study were to: (1) examine discordance between dentists’ perception of the importance of diet in caries treatment planning and their actual provision of diet counseling to patients, and (2) identify dentists’ characteristics associated with their provision of diet counseling.

Design

The study used a cross-sectional study design consisting of a questionnaire survey in Japan.

Participants

The study queried dentists working in outpatient dental practices who were affiliated with the Dental Practice-Based Research Network Japan (JDPBRN), which aims to allow dentists to investigate research questions and share experiences and expertise (n = 282).

Measurement

Dentists were asked about their perceptions on the importance of diet and their practice patterns regarding diet counseling, as well as patient, practice, and dentist background data.

Results

The majority of participants (n = 116, 63%) recognized that diet is “more important” to oral health. However, among participants who think diet is “more important” (n = 116), only 48% (n = 56) provide diet counseling to more than 20% of their patients. Multiple logistic regression analysis suggested that several variables were associated with providing diet counseling; dentist gender, practice busyness, percentage of patients interested in caries prevention, caries risk assessment, and percentage of patients who receive blood pressure screening.

Conclusions

Some discordance exists between dentists’ perception of the importance of diet in caries treatment planning and their actual practice pattern regarding diet counseling to patients. Reducing this discordance may require additional dentist education, including nutritional and systemic disease concepts; patient education to increase perception of the importance of caries prevention; or removing barriers to practices’ implementation of counseling.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01680848","term_id":"NCT01680848"}}NCT01680848     

Effects of Warm Ischemic Time on Gene Expression Profiling in Colorectal Cancer Tissues and Normal Mucosa

Background

Genome-wide gene expression analyses of tumors are a powerful tool to identify gene signatures associated with biologically and clinically relevant characteristics and for several tumor types are under clinical validation by prospective trials. However, handling and processing of clinical specimens may significantly affect the molecular data obtained from their analysis. We studied the effects of tissue handling time on gene expression in human normal and tumor colon tissues undergoing routine surgical procedures.

Methods

RNA extracted from specimens of 15 patients at four time points (for a total of 180 samples) after surgery was analyzed for gene expression on high-density oligonucleotide microarrays. A mixed-effects model was used to identify probes with different expression means across the four different time points. The p-values of the model were adjusted with the Bonferroni method.

Results

Thirty-two probe sets associated with tissue handling time in the tumor specimens, and thirty-one in the normal tissues, were identified. Most genes exhibited moderate changes in expression over the time points analyzed; however four of them were oncogenes, and two confirmed the effect of tissue handling by independent validation.

Conclusions

Our results suggest that a critical time point for tissue handling in colon seems to be 60 minutes at room temperature. Although the number of time-dependent genes we identified was low, the three genes that already showed changes at this time point in tumor samples were all oncogenes, hence recommending standardization of tissue-handling protocols and effort to reduce the time from specimen removal to snap freezing accounting for warm ischemia in this tumor type.     

Reduction of apoptosis and preservation of mitochondrial integrity under ischemia/reperfusion injury is mediated by estrogen receptor β

Background

Estrogen improves cardiac recovery after ischemia/reperfusion (I/R) by yet incompletely understood mechanisms. Mitochondria play a crucial role in I/R injury through cytochrome c-dependent apoptosis activation. We tested the hypothesis that 17β-estradiol (E2) as well as a specific ERβ agonist improve cardiac recovery through estrogen receptor (ER)β-mediated mechanisms by reducing mitochondria-induced apoptosis and preserving mitochondrial integrity.

Methods

We randomized ovariectomized C57BL/6N mice 24h before I/R to pre-treatment with E2 or a specific ERβ agonist (ERβA). Isolated hearts were perfused for 20min prior to 30min global ischemia followed by 40min reperfusion.

Results

Compared with controls, ERβA and E2 treated groups showed a significant improvement in cardiac recovery, i.e. an increase in left ventricular developed pressure, dP/dtmax and dP/dtmin. ERβA and E2 pre-treatment led to a significant reduction in apoptosis with decreased cytochrome c release from the mitochondria and increased mitochondrial levels of anti-apoptotic Bcl2 and ACAA2. Protein levels of mitochondrial translocase inner membrane (TIM23) and mitochondrial complex I of respiratory chain were increased by ERβA and E2 pre-treatment. Furthermore, we found a significant increase of myosin light chain 2 (MLC2) phosphorylation together with ERK1/2 activation in E2, but not in ERβA treated groups.

Conclusions

Activation of ERβ is essential for the improvement of cardiac recovery after I/R through the inhibition of apoptosis and preservation of mitochondrial integrity and can be a achieved by a specific ERβ agonist. Furthermore, E2 modulates MLC2 activation after I/R independent of ERβ.

     

Integrated Taxonomy and DNA Barcoding of Alpine Midges (Diptera: Chironomidae)

Rapid and efficient DNA-based tools are recommended for the evaluation of the insect biodiversity of high-altitude streams. In the present study, focused principally on larvae of the genus Diamesa Meigen 1835 (Diptera: Chironomidae), the congruence between morphological/molecular delimitation of species as well as performances in taxonomic assignments were evaluated. A fragment of the mitochondrial cox1 gene was obtained from 112 larvae, pupae and adults (Diamesinae, Orthocladiinae and Tanypodinae) that were collected in different mountain regions of the Alps and Apennines. On the basis of morphological characters 102 specimens were attributed to 16 species, and the remaining ten specimens were identified to the genus level. Molecular species delimitation was performed using: i) distance-based Automatic Barcode Gap Discovery (ABGD), with no a priori assumptions on species identification; and ii) coalescent tree-based approaches as the Generalized Mixed Yule Coalescent model, its Bayesian implementation and Bayesian Poisson Tree Processes. The ABGD analysis, estimating an optimal intra/interspecific nucleotide distance threshold of 0.7%-1.4%, identified 23 putative species; the tree-based approaches, identified between 25–26 entities, provided nearly identical results. All species belonging to zernyi, steinboecki, latitarsis, bertrami, dampfi and incallida groups, as well as outgroup species, are recovered as separate entities, perfectly matching the identified morphospecies. In contrast, within the cinerella group, cases of discrepancy arose: i) the two morphologically separate species D. cinerella and D. tonsa are neither monophyletic nor diagnosable exhibiting low values of between-taxa nucleotide mean divergence (0.94%); ii) few cases of larvae morphological misidentification were observed. Head capsule color is confirmed to be a valid character able to discriminate larvae of D. zernyi, D. tonsa and D. cinerella, but it is here better defined as a color gradient between the setae submenti and genal setae. DNA barcodes performances were high: average accuracy was ~89% and precision of ~99%. On the basis of the present data, we can thus conclude that molecular identification represents a promising tool that could be effectively adopted in evaluating biodiversity of high-altitude streams.     

Associations of Whole Blood n-3 and n-6 Polyunsaturated Fatty Acids with Blood Pressure in Children and Adolescents – Results from the IDEFICS/I.Family Cohort

BackgroundPolyunsaturated n-3 and n-6 polyunsaturated fatty acids (PUFA) are precursors of biologically active metabolites that affect blood pressure (BP) regulation. This study investigated the association of n-3 and n-6 PUFA and BP in children and adolescents.MethodsIn a subsample of 1267 children aged 2–9 years at baseline of the European IDEFICS (Identification and prevention of dietary- and lifestyle-induced health effects in children and infants) cohort whole blood fatty acids were measured by a validated gas chromatographic method. Systolic and diastolic BP was measured at baseline and after two and six years. Mixed-effects models were used to assess the associations between fatty acids at baseline and BP z-scores over time adjusting for relevant covariables. Models were further estimated stratified by sex and weight status.ResultsThe baseline level of arachidonic acid was positively associated with subsequent systolic BP (β = 0.08, P = 0.002) and diastolic BP (β = 0.07, P<0.001). In thin/normal weight children, baseline alpha-linolenic (β = -1.13, P = 0.003) and eicosapentaenoic acid (β = -0.85, P = 0.003) levels were inversely related to baseline and also to subsequent systolic BP and alpha-linolenic acid to subsequent diastolic BP. In overweight/obese children, baseline eicosapentaenoic acid level was positively associated with baseline diastolic BP (β = 0.54, P = 0.005).ConclusionsLow blood arachidonic acid levels in the whole sample and high n-3 PUFA levels in thin/normal weight children are associated with lower and therefore healthier BP. The beneficial effects of high n-3 PUFA on BP were not observed in overweight/obese children, suggesting that they may have been overlaid by the unfavorable effects of excess weight.     

Plasmid Characterization and Chromosome Analysis of Two netF+ Clostridium perfringens Isolates Associated with Foal and Canine Necrotizing Enteritis

The recent discovery of a novel beta-pore-forming toxin, NetF, which is strongly associated with canine and foal necrotizing enteritis should improve our understanding of the role of type A Clostridium perfringens associated disease in these animals. The current study presents the complete genome sequence of two netF-positive strains, JFP55 and JFP838, which were recovered from cases of foal necrotizing enteritis and canine hemorrhagic gastroenteritis, respectively. Genome sequencing was done using Single Molecule, Real-Time (SMRT) technology-PacBio and Illumina Hiseq2000. The JFP55 and JFP838 genomes include a single 3.34 Mb and 3.53 Mb chromosome, respectively, and both genomes include five circular plasmids. Plasmid annotation revealed that three plasmids were shared by the two newly sequenced genomes, including a NetF/NetE toxins-encoding tcp-conjugative plasmid, a CPE/CPB2 toxins-encoding tcp-conjugative plasmid and a putative bacteriocin-encoding plasmid. The putative beta-pore-forming toxin genes, netF, netE and netG, were located in unique pathogenicity loci on tcp-conjugative plasmids. The C. perfringens JFP55 chromosome carries 2,825 protein-coding genes whereas the chromosome of JFP838 contains 3,014 protein-encoding genes. Comparison of these two chromosomes with three available reference C. perfringens chromosome sequences identified 48 (~247 kb) and 81 (~430 kb) regions unique to JFP55 and JFP838, respectively. Some of these divergent genomic regions in both chromosomes are phage- and plasmid-related segments. Sixteen of these unique chromosomal regions (~69 kb) were shared between the two isolates. Five of these shared regions formed a mosaic of plasmid-integrated segments, suggesting that these elements were acquired early in a clonal lineage of netF-positive C. perfringens strains. These results provide significant insight into the basis of canine and foal necrotizing enteritis and are the first to demonstrate that netF resides on a large and unique plasmid-encoded locus.