bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxidative Stressors Modify the Response of Streptococcus mutans to Its Competence Signal Peptides
Authors: De Furio Matthew , Ahn Sang Joon , Burne Robert A. , Hagen Stephen J. 
Published: September 2017

ABSTRACT

The dental caries pathogen
Streptococcus mutans
is continually exposed to several types of stress in the oral biofilm environment. Oxidative stress generated by reactive oxygen species has a major impact on the establishment, persistence, and virulence of
S. mutans
. Here, we combined fluorescent reporter-promoter fusions with single-cell imaging to study the effects of reactive oxygen species on activation of genetic competence in
S. mutans
. Exposure to paraquat, which generates superoxide anion, produced a qualitatively different effect on activation of expression of the gene for the master competence regulator, ComX, than did treatment with hydrogen peroxide (H
2
O
2
), which can yield hydroxyl radical. Paraquat suppressed peptide-mediated induction of
comX
in a progressive and cumulative fashion, whereas the response to H
2
O
2
displayed a strong threshold behavior. Low concentrations of H
2
O
2
had little effect on induction of
comX
or the bacteriocin gene
cipB
, but expression of these genes declined sharply if extracellular H
2
O
2
exceeded a threshold concentration. These effects were not due to decreased reporter gene fluorescence. Two different threshold concentrations were observed in the response to H
2
O
2
, depending on the gene promoter that was analyzed and the pathway by which the competence regulon was stimulated. The results show that paraquat and H
2
O
2
affect the
S. mutans
competence signaling pathway differently, and that some portions of the competence signaling pathway are more sensitive to oxidative stress than others.

IMPORTANCE
Streptococcus mutans
inhabits the oral biofilm, where it plays an important role in the development of dental caries. Environmental stresses such as oxidative stress influence the growth of
S. mutans
and its important virulence-associated behaviors, such as genetic competence.
S. mutans
competence development is a complex behavior that involves two different signaling peptides and can exhibit cell-to-cell heterogeneity. Although oxidative stress is known to influence
S. mutans
competence, it is not understood how oxidative stress interacts with the peptide signaling or affects heterogeneity. In this study, we used fluorescent reporters to probe the effect of reactive oxygen species on competence signaling at the single-cell level. Our data show that different reactive oxygen species have different effects on
S. mutans
competence, and that some portions of the signaling pathway are more acutely sensitive to oxidative stress than others.
Acyl-Homoserine Lactone Production in Nitrifying Bacteria of the Genera Nitrosospira, Nitrobacter, and Nitrospira Identified via a Survey of Putative Quorum-Sensing Genes
Authors: Mellbye Brett L. , Spieck Eva , Bottomley Peter J. , Sayavedra-Soto Luis A. 
Published: September 2017

ABSTRACT

The genomes of many bacteria that participate in nitrogen cycling through the process of nitrification contain putative genes associated with acyl-homoserine lactone (AHL) quorum sensing (QS). AHL QS or bacterial cell-cell signaling is a method of bacterial communication and gene regulation and may be involved in nitrogen oxide fluxes or other important phenotypes in nitrifying bacteria. Here, we carried out a broad survey of AHL production in nitrifying bacteria in three steps. First, we analyzed the evolutionary history of AHL synthase and AHL receptor homologs in sequenced genomes and metagenomes of nitrifying bacteria to identify AHL synthase homologs in ammonia-oxidizing bacteria (AOB) of the genus
Nitrosospira
and nitrite-oxidizing bacteria (NOB) of the genera
Nitrococcus
,
Nitrobacter
, and
Nitrospira
. Next, we screened cultures of both AOB and NOB with uncharacterized AHL synthase genes and AHL synthase-negative nitrifiers by a bioassay. Our results suggest that an AHL synthase gene is required for, but does not guarantee, cell density-dependent AHL production under the conditions tested. Finally, we utilized mass spectrometry to identify the AHLs produced by the AOB
Nitrosospira multiformis
and
Nitrosospira briensis
and the NOB
Nitrobacter vulgaris
and
Nitrospira moscoviensis
as
N
-decanoyl-
l
-homoserine lactone (C
10
-HSL),
N
-3-hydroxy-tetradecanoyl-
l
-homoserine lactone (3-OH-C
14
-HSL), a monounsaturated AHL (C
10:1
-HSL), and
N
-octanoyl-
l
-homoserine lactone (C
8
-HSL), respectively. Our survey expands the list of AHL-producing nitrifiers to include a representative of
Nitrospira
lineage II and suggests that AHL production is widespread in nitrifying bacteria.

IMPORTANCE
Nitrification, the aerobic oxidation of ammonia to nitrate via nitrite by nitrifying microorganisms, plays an important role in environmental nitrogen cycling from agricultural fertilization to wastewater treatment. The genomes of many nitrifying bacteria contain genes associated with bacterial cell-cell signaling or quorum sensing (QS). QS is a method of bacterial communication and gene regulation that is well studied in bacterial pathogens, but less is known about QS in environmental systems. Our previous work suggested that QS might be involved in the regulation of nitrogen oxide gas production during nitrite metabolism. This study characterized putative QS signals produced by different genera and species of nitrifiers. Our work lays the foundation for future experiments investigating communication between nitrifying bacteria, the purpose of QS in these microorganisms, and the manipulation of QS during nitrification.
High Substrate Uptake Rates Empower Vibrio natriegens as Production Host for Industrial Biotechnology
Authors: Hoffart Eugenia , Grenz Sebastian , Lange Julian , Nitschel Robert , Müller Felix , Schwentner Andreas , Feith André , Lenfers-Lücker Mira , Takors Ralf , Blombach Bastian 
Published: September 2017

ABSTRACT

The productivity of industrial fermentation processes is essentially limited by the biomass-specific substrate consumption rate (

q
S

) of the applied microbial production system. Since

q
S

depends on the growth rate (μ), we highlight the potential of the fastest-growing nonpathogenic bacterium,
Vibrio natriegens
, as a novel candidate for future biotechnological processes.
V. natriegens
grows rapidly in BHIN complex medium with a μ of up to 4.43 h
−1
(doubling time of 9.4 min) as well as in minimal medium supplemented with various industrially relevant substrates. Bioreactor cultivations in minimal medium with glucose showed that
V. natriegens
possesses an exceptionally high

q
S

under aerobic (3.90 ± 0.08 g g
−1
h
−1
) and anaerobic (7.81 ± 0.71 g g
−1
h
−1
) conditions. Fermentations with resting cells of genetically engineered
V. natriegens
under anaerobic conditions yielded an overall volumetric productivity of 0.56 ± 0.10 g alanine liter
−1
min
−1
(i.e., 34 g liter
−1
h
−1
). These inherent properties render
V. natriegens
a promising new microbial platform for future industrial fermentation processes operating with high productivity.

IMPORTANCE
Low conversion rates are one major challenge to realizing microbial fermentation processes for the production of commodities operating competitively with existing petrochemical approaches. For this reason, we screened for a novel platform organism possessing characteristics superior to those of traditionally employed microbial systems. We identified the fast-growing
V. natriegens
, which exhibits a versatile metabolism and shows striking growth and conversion rates, as a solid candidate to reach outstanding productivities. Due to these inherent characteristics,
V. natriegens
can speed up common laboratory routines, is suitable for already existing production procedures, and forms an excellent foundation for engineering next-generation bioprocesses.
Impact of “Raised without Antibiotics” Beef Cattle Production Practices on Occurrences of Antimicrobial Resistance
Authors: Vikram Amit , Rovira Pablo , Agga Getahun E. , Arthur Terrance M. , Bosilevac Joseph M. , Wheeler Tommy L. , Morley Paul S. , Belk Keith E. , Schmidt John W. 
Published: September 2017

ABSTRACT

The specific antimicrobial resistance (AMR) decreases that can be expected from reducing antimicrobial (AM) use in U.S. beef production have not been defined. To address this data gap, feces were recovered from 36 lots of “raised without antibiotics” (RWA) and 36 lots of “conventional” (CONV) beef cattle. Samples (
n
= 719) were collected during harvest and distributed over a year. AMR was assessed by (i) the culture of six AM-resistant bacteria (ARB), (ii) quantitative PCR (qPCR) for 10 AMR genes (ARGs), (iii) a qPCR array of 84 ARGs, and (iv) metagenomic sequencing. Generally, AMR levels were similar, but some were higher in CONV beef cattle. The prevalence of third-generation cephalosporin-resistant (3GC
r
)
Escherichia coli
was marginally different between production systems (CONV, 47.5%; RWA, 34.8%;
P
= 0.04), but the seasonal effect (summer, 92.8%; winter, 48.3%;
P
< 0.01) was greater. Erythromycin-resistant (ERY
r
)
Enterococcus
sp. concentrations significantly differed between production systems (CONV, 1.91 log
10
CFU/g; RWA, 0.73 log
10
CFU/g;
P
< 0.01). Levels of
aadA1
,
ant
(
6
)-
I
,
bla
ACI
,
erm
(A),
erm
(B),
erm
(C),
erm
(F),
erm
(Q),
tet
(A),
tet
(B),
tet
(M), and
tet
(X) ARGs were higher (
P
< 0.05) in the CONV system. Aggregate abundances of all 43 ARGs detected by metagenomic sequencing and the aggregate abundances of ARGs in the aminoglycoside, β-lactam, macrolide-lincosamide-streptogramin B (MLS), and tetracycline AM classes did not differ (log
2
fold change < 1.0) between CONV and RWA systems. These results suggest that further reductions of AM use in U.S. beef cattle production may not yield significant AMR reductions beyond MLS and tetracycline resistance.

IMPORTANCE
The majority of antimicrobial (AM) use in the United States is for food-animal production, leading to concerns that typical AM use patterns during “conventional” (CONV) beef cattle production in the United States contribute broadly to antimicrobial resistance (AMR) occurrence. In the present study, levels of AMR were generally similar between CONV and “raised without antibiotics” (RWA) cattle. Only a limited number of modest AMR increases was observed in CONV cattle, primarily involving macrolide-lincosamide-streptogramin B (MLS) and tetracycline resistance. Macrolides (tylosin) and tetracyclines (chlortetracycline) are administered in-feed for relatively long durations to reduce liver abscesses. To ensure judicious AM use, the animal health, economic, and AMR impacts of shorter duration in-feed administration of these AMs should be examined. However, given the modest AMR reductions observed, further reductions of AM use in U.S. beef cattle production may not yield significant AMR reductions beyond MLS and tetracycline resistance.
Identifying the Active Microbiome Associated with Roots and Rhizosphere Soil of Oilseed Rape
Authors: Gkarmiri Konstantia , Mahmood Shahid , Ekblad Alf , Alström Sadhna , Högberg Nils , Finlay Roger 
Published: September 2017

ABSTRACT

RNA stable isotope probing and high-throughput sequencing were used to characterize the active microbiomes of bacteria and fungi colonizing the roots and rhizosphere soil of oilseed rape to identify taxa assimilating plant-derived carbon following
13
CO
2
labeling. Root- and rhizosphere soil-associated communities of both bacteria and fungi differed from each other, and there were highly significant differences between their DNA- and RNA-based community profiles.
Verrucomicrobia
,
Proteobacteria
,
Planctomycetes
,
Acidobacteria
,
Gemmatimonadetes
,
Actinobacteria
, and
Chloroflexi
were the most active bacterial phyla in the rhizosphere soil.
Bacteroidetes
were more active in roots. The most abundant bacterial genera were well represented in both the
13
C- and
12
C-RNA fractions, while the fungal taxa were more differentiated.
Streptomyces
,
Rhizobium
, and
Flavobacterium
were dominant in roots, whereas
Rhodoplanes
and
Sphingomonas
(
Kaistobacter
) were dominant in rhizosphere soil. “
Candidatus
Nitrososphaera” was enriched in
13
C in rhizosphere soil.
Olpidium
and
Dendryphion
were abundant in the
12
C-RNA fraction of roots;
Clonostachys
was abundant in both roots and rhizosphere soil and heavily
13
C enriched.
Cryptococcus
was dominant in rhizosphere soil and less abundant, but was
13
C enriched in roots. The patterns of colonization and C acquisition revealed in this study assist in identifying microbial taxa that may be superior competitors for plant-derived carbon in the rhizosphere of
Brassica napus
.

IMPORTANCE
This microbiome study characterizes the active bacteria and fungi colonizing the roots and rhizosphere soil of
Brassica napus
using high-throughput sequencing and RNA-stable isotope probing. It identifies taxa assimilating plant-derived carbon following
13
CO
2
labeling and compares these with other less active groups not incorporating a plant assimilate.
Brassica napus
is an economically and globally important oilseed crop, cultivated for edible oil, biofuel production, and phytoextraction of heavy metals; however, it is susceptible to several diseases. The identification of the fungal and bacterial species successfully competing for plant-derived carbon, enabling them to colonize the roots and rhizosphere soil of this plant, should enable the identification of microorganisms that can be evaluated in more detailed functional studies and ultimately be used to improve plant health and productivity in sustainable agriculture.
Striatal molecular alterations in HD gene carriers: a systematic review and meta-analysis of PET studies
Authors: Niccolini Flavia , Pagano Gennaro , Fusar-Poli Paolo , Wood Andrew , Mrzljak Ladislav , Sampaio Cristina , Politis Marios 
Published: September 2017

BackgroundOver the past years, positron emission tomography (PET) imaging studies have investigated striatal molecular changes in premanifest and manifest Huntington’s disease (HD) gene expansion carriers (HDGECs), but they have yielded inconsistent results.ObjectiveTo systematically examine the evidence of striatal molecular alterations in manifest and premanifest HDGECs as measured by PET imaging studies.MethodsMEDLINE, ISI Web of Science, Cochrane Library and Scopus databases were searched for articles published until 7 June 2017 that included PET studies in manifest and premanifest HDGECs. Meta-analyses were conducted with random effect models, and heterogeneity was addressed with I2 index, controlling for publication bias and quality of study. The primary outcome was the standardised mean difference (SMD) of PET uptakes in the whole striatum, caudate and putamen in manifest and premanifest HDGECs compared with healthy controls (HCs).ResultsTwenty-four out of 63 PET studies in premanifest (n=158) and manifest (n=191) HDGECs and HCs (n=333) were included in the meta-analysis. Premanifest and manifest HDGECs showed significant decreases in dopamine D2 receptors in caudate (SMD=−1.233, 95% CI −1.753 to −0.713, p<0.0001; SMD=−5.792, 95% CI −7.695 to −3.890, p<0.0001) and putamen (SMD=−1.479, 95% CI −1.965 to −0.992, p<0.0001; SMD=−5.053, 95% CI −6.558 to −3.549, p<0.0001), in glucose metabolism in caudate (SMD=−0.758, 95% CI −1.139 to −0.376, p<0.0001; SMD=−3.738, 95% CI −4.880 to −2.597, p<0.0001) and putamen (SMD=−2.462, 95% CI −4.208 to −0.717, p=0.006; SMD=−1.650, 95% CI −2.842 to −0.458, p<0.001) and in striatal PDE10A binding (SMD=−1.663, 95% CI −2.603 to −0.723, p=0.001; SMD=−2.445, 95% CI −3.371 to −1.519, p<0.001).ConclusionsPET imaging has the potential to detect striatal molecular changes even at the early premanifest stage of HD, which are relevant to the neuropathological mechanisms underlying the development of the disease.
Analysis of known amyotrophic lateral sclerosis and frontotemporal dementia genes reveals a substantial genetic burden in patients manifesting both diseases not carrying the C9orf72 expansion mutation
Authors: Dols-Icardo Oriol , García-Redondo Alberto , Rojas-García Ricardo , Borrego-Hernández Daniel , Illán-Gala Ignacio , Muñoz-Blanco José Luís , Rábano Alberto , Cervera-Carles Laura , Juárez-Rufián Alexandra , Spataro Nino , De Luna Noemí , Galán Lucía , Cortes-Vicente Elena , Fortea Juan , Blesa Rafael , Grau-Rivera Oriol , Lleó Alberto , Esteban-Pérez Jesús , Gelpi Ellen , Clarimón Jordi 
Published: September 2017

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are part of a clinical, pathological and genetic continuum.ObjectivesThe purpose of the present study was to assess the mutation burden that is present in patients with concurrent ALS and FTD (ALS/FTD) not carrying the chromosome 9 open reading frame 72 (C9orf72) hexanucleotide repeat expansion, the most important genetic cause in both diseases.MethodsFrom an initial group of 973 patients with ALS, we retrospectively selected those patients fulfilling diagnostic criteria of concomitant ALS and FTD lacking the repeat expansion mutation in C9orf72. Our final study group consisted of 54 patients clinically diagnosed with ALS/FTD (16 with available postmortem neuropathological diagnosis). Data from whole exome sequencing were used to screen for mutations in known ALS and/or FTD genes.ResultsWe identified 11 patients carrying a probable pathogenic mutation, representing an overall mutation frequency of 20.4%. TBK1 was the most important genetic cause of ALS/FTD (n=5; 9.3%). The second most common mutated gene was SQSTM1, with three mutation carriers (one of them also harboured a TBK1 mutation). We also detected probable pathogenic genetic alterations in TAF15, VCP and TARDBP and possible pathogenic mutations in FIG4 and ERBB4.ConclusionOur results indicate a high genetic burden underlying the co-occurrence of ALS and FTD and expand the phenotype associated with TAF15, FIG4 and ERBB4 to FTD. A systematic screening of ALS and FTD genes could be indicated in patients manifesting both diseases without the C9orf72 expansion mutation, regardless of family history of disease.
Impact of plain packaging of cigarettes on the risk perception of Uruguayan smokers: an experimental study
Authors: Harris Jeffrey E , Ares Gastón , Gerstenblüth Mariana , Machin Leandro , Triunfo Patricia 
Published: September 2017

BackgroundUruguay, a South American country of 3.4 million inhabitants that has already banned tobacco advertising, prohibited such terms as light, mild and low-tar and required graphic warnings covering 80% of cigarette packs, is considering the imposition of plain, standardised packaging.MethodsWe conducted an experimental choice-based conjoint analysis of the impact of alternative cigarette package designs on the risk perceptions of 180 adult current Uruguayan smokers. We compared plain packaging, with a standardised brand description and the dark brown background colour required on Australian cigarette packages, to two controls: the current package design with distinctive brand elements and colours; and a modified package design, with distinctive brand elements and the dark brown background colour. Graphic warnings were also varied.ResultsPlain packaging significantly reduced the probability of perceiving the stimulus cigarettes as less harmful in comparison to the current package design (OR 0.398, 95% CI 0.333 to 0.476, p<0.001) and the modified package design (OR 0.729, 95% CI 0.626 to 0.849, p<0.001).ConclusionsPlain packaging enhanced the perceived risk of cigarette products even in a highly regulated setting such as Uruguay. Both the elimination of distinctive brand elements and the use of Australia’s dark brown background colour contributed to the observed effect.
To what extent and why adolescents do or do not support future tobacco control measures: a multimethod study in the Netherlands
Authors: Schreuders Michael , Lagerweij Naomi A , van den Putte Bas , Kunst Anton E 
Published: September 2017

BackgroundIn the Netherlands, the adoption of new tobacco control measures is needed to further reduce rates of adolescent smoking. Adolescents’ support for future measures could increase the likelihood of adoption as this provides political leverage for tobacco control advocates. There is, however, scant evidence about to what extent and why adolescents support future measures. We therefore assessed adolescents’ support for a range of future measures and explored the criteria that adolescents use to underpin their support.MethodsA mixed-method design involved surveys and group interviews with fourth-year students (predominantly 15–16 years). The survey, completed by 345 adolescents, included statements about future tobacco control measures and a smoke-free future where nobody starts or continues smoking. Thereafter, 15 adolescents participated in five group interviews to discuss their support for future measures.ResultsThe survey showed that adolescents generally support a smoke-free future. They expressed most support for product measures, mixed support for smoke-free areas, ambivalent support for price increases and least support for sales restrictions. The group interviews revealed that differences in support were explained by adolescents’ criteria that future measures should: have the potential to be effective, not violate individuals’ right to smoke, protect children from pro-smoking social influences and protect non-smokers from secondhand smoke.ConclusionAdolescents’ high support for a smoke-free future does not lead to categorical support for any measure. Addressing the underlying criteria may increase adolescents’ support and therewith provide political leverage for the adoption of future measures.
Rapid estrogen receptor-α signaling mediated by ERK activation regulates vascular tone in male and ovary-intact female mice
Authors: Kim Seong Chul , Boese Austin C. , Moore Matthew H. , Cleland Rea M. , Chang Lin , Delafontaine Patrice , Yin Ke-Jie , Lee Jean-Pyo , Hamblin Milton H. 
Published: September 2017

Estrogen has been shown to affect vascular reactivity. Here, we assessed the estrogen receptor-α (ERα) dependency of estrogenic effects on vasorelaxation via a rapid nongenomic pathway in both male and ovary-intact female mice. We compared the effect of a primary estrogen, 17β-estradiol (E2) or 4,4′,4″-(4-propyl-[1H]pyrazole-1,3,5-triyl)tris-phenol (PPT; selective ERα agonist). We found that E2and PPT induced greater aortic relaxation in female mice than in male mice, indicating ERα mediation, which was further validated by using ERα antagonism. Treatment with 1,3-bis(4-hydroxyphenyl)-4-methyl-5-[4-(2-piperidinylethoxy)phenol]-1H-pyrazole dihydrochloride (MPP dihydrochloride; ERα antagonist) attenuated PPT-mediated vessel relaxation in both sexes. ERα-mediated vessel relaxation was further validated by the absence of significant PPT-mediated relaxation in aortas isolated from ERα knockout mice. Treatment with a specific ERK inhibitor, PD-98059, reduced E2-induced vessel relaxation in both sexes but to a lesser extent in female mice. Furthermore, PD-98059 prevented PPT-induced vessel relaxation in both sexes. Both E2and PPT treatment activated ERK as early as 5–10 min, which was attenuated by PD-98059 in aortic tissue, cultured primary vascular smooth muscle cells (VSMCs), and endothelial cells (ECs). Aortic rings denuded of endothelium showed no differences in vessel relaxation after E2or PPT treatment, implicating a role of ECs in the observed sex differences. Here, our results are unique to show estrogen-stimulated rapid ERα signaling mediated by ERK activation in aortic tissue, as well as VSMCs and ECs in vitro, in regulating vascular function by using side-by-side comparisons in male and ovary-intact female mice in response to E2or PPT.NEW & NOTEWORTHY Here, we assessed the estrogen receptor-α dependency of estrogenic effects in vasorelaxation of both male and ovary-intact female mice by performing side-by-side comparisons. Also, we describe the connection between estrogen-stimulated rapid estrogen receptor-α signaling and downstream ERK activation in regulating vascular function in male and ovary-intact female mice.