bluuebunny/crossref_metadata_2025 huggingface dataset:
Antibiotic administration alleviates the aggravating effect of orthodontic force on ligature‐induced experimental periodontitis bone loss in mice
Authors: Shi J. , Liu Z. , Kawai T. , Zhou Y. , Han X.
Published: February 2017

Background and Objectives

It is recognized that orthodontic force (OF) has an aggravating effect on the progression of destructive periodontitis if periodontitis have not been well controlled. However, the underlying mechanism is not completely clear. This study was to investigate the effect of antibiotic administration on OF‐aggravated, ligature‐induced experimental periodontitis in mice.

Material and Methods

C57BL/6 mice (male, 8 wk old) were divided into three groups (n = 8). Silk ligatures (SL) were tied around the maxillary right (group 1) or both (groups 2 and 3) first molars on day 0, removed on day 8 and systemic antibiotics was administered through drinking water (group 3) since day 8. OF was applied on the maxillary right first molars since day 13 (groups 2 and 3). All mice were killed on day 20.

Results

Total oral bacteria load was significantly higher in group 2 when compared to group 1 on day 20, whereas such count was greatly reduced in group 3 when antibiotics were administered. Periodontal bone loss was significantly increased on SL side vs. control side in group 1. Periodontal bone loss was significantly increased on OF + SL side vs. SL side in group 2 (p < 0.05) but not in group 3 when systemic antibiotics were administered. Gingival mRNA and protein expressions of receptor activator of nuclear factor kappa‐B ligand/osteoprotegerin were significantly increased on OF + SL side vs. SL side in group 2 (p < 0.01) but not in group 3. However, comparable levels of tartrate‐resistant acid phosphatase‐positive cell formation within periodontal space and tooth movement were observed on OF + SL side in groups 2 and 3.

Conclusion

Our results suggest that reduction of oral bacterial load by antibiotic administration alleviate orthodontic force‐aggravated periodontitis bone loss.
The extrusion test and sensory perception revisited: Some comments on generality and the effect of measurement temperature
Authors: Brenner Tom , Tomczyńska‐Mleko Marta , Mleko Stanisław , Nishinari Katsuyoshi
Published: February 2017

Relations between sensory perception, extrusion and fracture in shear, extension and compression are examined. Gelatin‐based gels are perceived as less firm and less hard than expected based on their mechanical properties compared to polysaccharide gels that have the same mechanical properties at room temperature but melt well above body temperature, underlying the importance of the measurement temperature for gels that melt during mastication. Correlations between parameters from extrusion and compression, extension and shear are verified using mixed polysaccharide gels.

Practical applications

We previously reported a high correlation between several sensory attributes and parameters from an extrusion test. The extrusion test showed the most robust correlation, and could be used to assess samples at both extremes of the texture range with respect to elasticity, for example, both samples that could not be extended as their very low elasticity led to their fracture during handling, as well as samples that could not be fractured in compression. Here, we reexamine the validity of the relations reported. We demonstrate the generality of the relations between large deformation tests and extrusion, but the findings underscore the need to take into account the measurement temperature for samples that melt during mastication when correlating instrumental parameters with sensory perception.
Association of Hypercalcemia Before Treatment With Hypocalcemia After Treatment in Dogs With Primary Hyperparathyroidism
Authors: Dear J.D. , Kass P.H. , Della Maggiore A.M. , Feldman E.C.
Published: February 2017

Background

Development of hypocalcemia after treatment of hyperparathyroidism results in increased costs and risk of poorer outcomes. Previous studies have shown conflicting data about predictors of hypocalcemia after these procedures.

Hypothesis/Objectives

The objective of this study was to investigate whether ionized calcium (iCa) concentrations before treatment are predictive of hypocalcemia or its clinical signs after surgical removal or heat ablation in dogs with primary hyperparathyroidism.

Animals

Fifty‐four dogs with primary hyperparathyroidism (29 female, 25 male; 49 retrospective, 5 prospective).

Methods

Dogs were enrolled if they met the inclusion criteria: persistent hypercalcemia (iCa >1.41 mmol/L) due to primary hyperparathyroidism and absence of preemptive calcitriol treatment. All dogs were treated with parathyroidectomy (n = 37) or percutaneous ultrasound‐guided heat ablation (n = 17). After treatment,iCa was monitored twice daily until plateau or intervention.

Results

There was a moderate correlation between before‐treatment hypercalcemia and after‐treatment hypocalcemia. The prospective study was terminated due to ethical concerns given findings in the retrospective section. All dogs were placed into groups according to their pretreatmentiCa: 1.46–1.61 mmol/L, 1.62–1.71 mmol/L,iCa 1.72–1.81 mmol/L, or >1.81 mmol/L. After treatment, the mean lowestiCa for each group, respectively, was 1.19, 1.18, 1.13, and 1.01 mmol/L. There was a significant association between higher group and proportion of dogs withiCa <1.00 mmol/L (P= .014).

Conclusions and Clinical Importance

This study demonstrates a moderate correlation betweeniCa concentration before treatment and hypocalcemia after treatment. Dogs with higher initialiCa concentrations should be treated to prevent rapid decline and development of clinical hypocalcemia.
Management and prognosis of hepatocellular carcinoma in the elderly: Results of an in‐field multicenter cohort study
Authors: Borzio Mauro , Dionigi Elena , Vitale Alessandro , Rossini Angelo , Marignani Massimo , Fornari Fabio , Vicari Susanna , De Sio Ilario , Farinati Fabio , Bertolini Emanuela , Oliveri Filippo , Leandro Gioacchino , Francica Giampiero , Mitra Mario , Omazzi Barbara , Boccia Sergio , Salmi Andrea , Toldi Anna , Sacco Rodolfo
Published: February 2017

Aims

This multicentre cohort study evaluated the role of ageing on clinical characteristics, treatment allocation and outcome of new hepatocellular carcinomas (HCCs), in clinical practice.

Material & Methods

From September 2008, 541 patients >70 years old (elderly group), and 527 ≤70 years old (non‐elderly group) with newly diagnosed HCC were consecutively enrolled in 30 Italian centres. Differences in clinical characteristics and treatment allocation between groups were described by a multivariable logistic regression model measuring the inverse probability weight to meet the elderly group. Survival differences were measured by unadjusted and adjusted (by inverse probability weight) survival analysis.

Results

Elderly patients were mainly females, hepatitis C virus infected and with better conserved liver function (P<.001). At presentation, HCC median size was similar in both groups while, in youngers, HCC was more frequently multinodular (P=.001), and associated with neoplastic thrombosis (P=.009). Adjusted survival analysis showed that age did not predict short–mid‐term survival (within 24 months), while it was a significant independent predictor of long‐term survival. Moreover, age had a significant long‐term survival impact mainly on early HCC stages (Barcelona Clinic for Liver Cancer [BCLC] 0‐A), its impact on BCLC B stage was lower, while it was negligible for advanced‐terminal stages.

Conclusions

Age per se does not impact on short–mid‐term prognosis (≤24 months) of HCC patients, and should not represent a limitation to its management.
“The First Intervention Is Leaving Home”: Reasons for Electing an Out‐of‐hospital Birth among Minnesotan Mothers
Authors: Hazen Helen
Published: February 2017

The Twin Cities (Minneapolis–St. Paul), Minnesota, has seen a recent increase in the number of mothers seeking an out‐of‐hospital birth. This research uses in‐depth interviews with 24 mothers who intended an out‐of‐hospital birth in the previous two years, exploring their reasons for pursuing an alternative approach to birth. For many women, an out‐of‐hospital birth fits within a philosophy that rejects the pathologizing of birth. Escaping rigid hospital protocols is seen as critical to avoiding what many mothers described as unnecessary interventions. In addition, homebirth midwives are perceived as offering more holistic care for the expectant and new mother. Home itself is seen as providing a more pleasant and calm, family‐friendly atmosphere than a hospital, helping the mother relax, with the expectation that this will expedite labor. Many of the recommendations developed here have applicability to improving hospital birth experiences as well as furthering our understanding of out‐of‐hospital birth.
Reciprocal translocation of small numbers of inbred individuals rescues immunogenetic diversity
Authors: Grueber Catherine E. , Sutton Jolene T. , Heber Sol , Briskie James V. , Jamieson Ian G. , Robertson Bruce C.
Published: February 2017

Genetic rescue can reduce inbreeding depression and increase fitness of small populations, even when the donor populations are highly inbred. In a recent experiment involving two inbred island populations of the New Zealand South Island robin, Petroica australis, reciprocal translocations improved microsatellite diversity and individual fitness. While microsatellite loci may reflect patterns of genome‐wide diversity, they generally do not indicate the specific genetic regions responsible for increased fitness. We tested the effectiveness of this reciprocal translocation for rescuing diversity of two immunogenetic regions: Toll‐like receptor (TLR) and major histocompatibility complex (MHC) genes. We found that the relatively small number of migrants (seven and ten per island) effectively brought the characteristic TLR gene diversity of each source population into the recipient population. However, when migrants transmitted TLR alleles that were already present at high frequency in the recipient population, it was possible for offspring of mixed heritage to have decreased gene diversity compared to recipient population diversity prior to translocation. In contrast to TLRs, we did not observe substantial changes in MHC allelic diversity following translocation, with limited evidence of a decrease in differentiation, perhaps because most MHC alleles were observed at both sites prior to the translocation. Overall, we conclude that small numbers of migrants may successfully restore the diversity of immunogenetic loci with few alleles, but that translocating larger numbers of animals would provide additional opportunity for the genetic rescue of highly polymorphic immunity regions, such as the MHC, even when the source population is inbred.
Nesting habits influence population genetic structure of a bee living in anthropogenic disturbance
Authors: Vickruck J. L. , Richards M. H.
Published: February 2017

While most organisms are negatively affected by anthropogenic disturbance, a few species thrive in landscapes altered by humans. Typically, native bees are negatively impacted by anthropogenic environmental change, including habitat alteration and climate change. Here, we investigate the population structure of the eastern carpenter bee Xylocopa virginica, a generalist pollinator with a broad geographic range spanning eastern North America. Eastern carpenter bees now nest almost exclusively in artificial wooden structures, linking their geographic distribution and population structure to human activities and disturbance. To investigate the population structure of these bees, we sampled females from 16 different populations from across their range. Nine species‐specific microsatellite loci showed that almost all populations are genetically distinct, but with high levels of genetic diversity and low levels of inbreeding overall. Broadly speaking, populations clustered into three distinct genetic groups: a northern group, a western group and a core group. The northern group had low effective population sizes, decreased genetic variability and the highest levels of inbreeding in the data set, suggesting that carpenter bees may be expanding their range northward. The western group was genetically distinct, but lacked signals of a recent range expansion. Climatic data showed that summer and winter temperatures explained a significant amount of the genetic differentiation seen among populations, while precipitation did not. Our results indicate that X. virginica may be one of the rare ‘anthrophilic’ species that thrive in the face of anthropogenic disturbance.
Population genetic structure and adaptation of malaria parasites on the edge of endemic distribution
Authors: Duffy Craig W. , Ba Hampate , Assefa Samuel , Ahouidi Ambroise D. , Deh Yacine B. , Tandia Abderahmane , Kirsebom Freja C. M. , Kwiatkowski Dominic P. , Conway David J.
Published: February 2017

To determine whether the major human malaria parasitePlasmodium falciparumexhibits fragmented population structure or local adaptation at the northern limit of its African distribution where the dry Sahel zone meets the Sahara, samples were collected from diverse locations within Mauritania over a range of ~1000 km. Microsatellite genotypes were obtained for 203 clinical infection samples from eight locations, and Illumina paired‐end sequences were obtained to yield high coverage genomewide single nucleotide polymorphism (SNP) data for 65 clinical infection samples from four locations. Most infections contained single parasite genotypes, reflecting low rates of transmission and superinfection locally, in contrast to the situation seen in population samples from countries further south. A minority of infections shared related or identical genotypes locally, indicating some repeated transmission of parasite clones without recombination. This caused some multilocus linkage disequilibrium and local divergence, but aside from the effect of repeated genotypes there was minimal differentiation between locations. Several chromosomal regions had elevated integrated haplotype scores (|iHS|) indicating recent selection, including those containing drug resistance genes. A genomewideFSTscan comparison with previous sequence data from an area in West Africa with higher infection endemicity indicates that regional gene flow prevents genetic isolation, but revealed allele frequency differentiation at three drug resistance loci and an erythrocyte invasion ligand gene. Contrast of extended haplotype signatures revealed none to be unique to Mauritania. Discrete foci of infection on the edge of the Sahara are genetically highly connected to the wider continental parasite population, and local elimination would be difficult to achieve without very substantial reduction in malaria throughout the region.
Comparative analysis of the transcriptional responses to low and high temperatures in three rice planthopper species
Authors: Huang Hai‐Jian , Xue Jian , Zhuo Ji‐Chong , Cheng Ruo‐Lin , Xu Hai‐Jun , Zhang Chuan‐Xi
Published: February 2017

The brown planthopper (Nilaparvata lugens, BPH), white‐backed planthopper (Sogatella furcifera, WBPH) and small brown planthopper (Laodelphax striatellus, SBPH) are important rice pests in Asia. These three species differ in thermal tolerance and exhibit quite different migration and overwintering strategies. To understand the underlying mechanisms, we sequenced and compared the transcriptome of the three species under different temperature treatments. We found that metabolism‐, exoskeleton‐ and chemosensory‐related genes were modulated. In high temperature (37 °C), heat shock protein (HSP) genes were the most co‐regulated; other genes related with fatty acid metabolism, amino acid metabolism and transportation were also differentially expressed. In low temperature (5 °C), the differences in gene expression of the genes for fatty acid synthesis, transport proteins and cytochrome P450 might explain why SBPH can overwinter in high latitudes, while BPH and WBPH cannot. In addition, other genes related with moulting, and membrane lipid composition might also play roles in resistance to low and high temperatures. Our study illustrates the common responses and different tolerance mechanisms of three rice planthoppers in coping with temperature change, and provides a potential strategy for pest management.
Nuclear localization of a putative Phytophthora sojae bZIP1 transcription factor is mediated by multiple targeting motifs
Authors: Fang Yufeng , Tyler Brett M.
Published: February 2017

Oomycetes are fungal‐like eukaryotic microbes in the kingdom Stramenopila. We recently found that the oomycete plant pathogen Phytophthora sojae uses nuclear localization signals (NLSs) for translocation of proteins into the nucleus that differ from conventional well‐characterized NLSs from mammals and yeast. Here, we have characterized in depth the NLSs of a P. sojae basic leucine zipper transcription factor, PsbZIP1. Nuclear localization of PsbZIP1 was determined by a central conserved region overlapping the DNA binding domain. Mutational analysis of this region identified four distinct elements that contributed multiplicatively to nuclear localization, but the conserved DNA binding residues were not required. Three of the elements showed autonomous NLS activity and the fourth served as a nuclear localization enhancer. Sequences within two of the nuclear localization elements defined a new form of bipartite NLS consisting of a triplet of basic residues followed by a tail of scattered basic amino acids.
Machiavellian flexibility in negative mate retention
Authors: JONES DANIEL N. , DE ROOS MELISSA S.
Published: February 2017

Among the Dark Triad traits (psychopathy, narcissism, and Machiavellianism), Machiavellianism is uniquely associated with flexibility. This flexibility should result in the use of aggressive short‐term tactics only when they do not interfere with long‐term goals. Study 1 found that individuals high in Machiavellianism differed from those high in psychopathy with respect to retrospective accounts of negative mate retention tactics. Study 2 found an interaction between Machiavellianism and relationship type such that individuals high in Machiavellianism tempered the use of negative tactics for long‐term (but not short‐term) relationships. The findings highlight the flexibility of the Machiavellianism construct and its relevance to mating strategies among the Dark Triad.
Successful resumption of peritoneal dialysis following living donor liver transplantation in children with end‐stage renal disease
Authors: Kanazawa Hiroyuki , Fukuda Akinari , Sato Mai , Ishimori Shingo , Sasaki Kengo , Uchida Hajime , Shigeta Takanobu , Mali Vidyadhar Padmakar , Sakamoto Seisuke , Ishikura Kenji , Kasahara Mureo
Published: February 2017

Children with ESRD in need of RRT are commonly managed by PD due to difficulty with vascular access for HD and the relatively large extracorporeal blood volume required. Major abdominal surgery may result in injury to the peritoneum and consequent adhesion, thereby resulting in a reduction in the anatomical capacity and transport capability across the peritoneal membrane. Here, we report successful resumption of PD after LDLT in two pediatric patients. The causes of ESRD were PH1 and juvenile nephronophthisis, respectively. Both patients were managed by PD prior to LDLT. PD was converted to HD starting three days before LDLT and was continued postoperatively until resumption of PD on days 13 and 28, respectively. The PD weekly Kt/V urea was maintained before and after LDLT. The patients continued to do well on PD without complications. Meticulous intra‐operative techniques during LDLT allow postoperative PD resumption by preservation of peritoneal integrity with effective transport capability and without added risk of peritonitis.
Blaming a Few Bad Apples to Save a Threatened Barrel: The System‐Justifying Function of Conspiracy Theories
Authors: Jolley Daniel , Douglas Karen M. , Sutton Robbie M.
Published: February 2017

This research demonstrates that conspiracy theories—often represented as subversive alternatives to establishment narratives—may bolster, rather than undermine, support for the social status quo when its legitimacy is under threat. A pilot study (N = 98) found a positive relationship between conspiracy belief and satisfaction with the status quo. In Study 1 (N = 120), threatening (vs. affirming) the status quo in British society caused participants to endorse conspiracy theories. In Study 2 (N = 159), exposure to conspiracy theories increased satisfaction with the British social system after this had been experimentally threatened. In Study 3 (N = 109), this effect was mediated by the tendency for participants exposed (vs. not exposed) to conspiracy theories to attribute societal problems relatively more strongly to small groups of people rather than systemic causes. By blaming tragedies, disasters, and social problems on the actions of a malign few, conspiracy theories can divert attention from the inherent limitations of social systems.
Placental pathology in HIV infection at term: a comparison with HIV‐uninfected women
Authors: Kalk Emma , Schubert Pawel , Bettinger Julie A. , Cotton Mark F. , Esser Monika , Slogrove Amy , Wright Colleen A.
Published: February 2017

Objectives

To describe and correlate placental characteristics from pregnancies in HIV‐infected and HIV‐negative women with maternal and infant clinical and immunological data.

Methods

Prospective descriptive study of placentas from term, uncomplicated vaginal births in a cohort of HIV‐infected (n = 120) and HIV‐negative (n = 103) women in Cape Town, South Africa. Microscopic and macroscopic features were used to determine pathological cluster diagnoses. The majority of HIV‐infected women received some form of drug treatment for the prevention of vertical transmission of HIV. Data were analysed using logistic regression.

Results

HIV‐infected women were older (median [IQR] 27.4 years [24–31] vs. 25.8 [23–30]), more likely to be multiparous (81.7% vs. 71.8%) and had lower CD4 counts (median [IQR] 323.5 cells/ml [235–442] vs. 467 [370–656]). There were no differences in gestational age at first antenatal visit or at delivery. The proportion of specimens with placental lesions was similar in both groups (39.2% vs. 44.7%). Half of all samples were below the tenth percentile expected‐weight‐for‐gestation regardless of HIV status. This was unaffected by adjustment for confounding variables. Maternal vascular malperfusion (MVM) was more frequent in HIV infection (24.2% vs. 12.6%; P = 0.028), an association which strengthened after adjustment (aOR 2.90 [95% confidence interval 1.11–7.57]). Otherwise the frequency of individual diagnoses did not differ between the groups on multivariate analysis.

Conclusions

In this cohort of term, uncomplicated pregnant women, few differences were observed between the HIV‐infected and uninfected groups apart from MVM. This lesion may underlie the development of hypertensive disorders of pregnancy, which have been observed at higher rates in some HIV‐infected women on ART.
Diuretic‐sensitive electroneutral Na+ movement and temperature effects on central axons
Authors: Kanagaratnam Meneka , Pendleton Christopher , Souza Danilo Almeida , Pettit Joseph , Howells James , Baker Mark D.
Published: February 2017

Key points

Optic nerve axons get less excitable with warming.

F‐fibre latency does not shorten at temperatures above 30°C.

Action potential amplitude falls when the Na+‐pump is blocked, an effect speeded by warming.

Diuretics reduce the rate of action potential fall in the presence of ouabain.

Our data are consistent with electroneutral entry of Na+ occurring in axons and contributing to setting the resting potential.

Raising the temperature of optic nerve from room temperature to near physiological has effects on the threshold, refractoriness and superexcitability of the shortest latency (fast, F) nerve fibres, consistent with hyperpolarization. The temperature dependence of peak impulse latency was weakened at temperatures above 30°C suggesting a temperature‐sensitive process that slows impulse propagation. The amplitude of the supramaximal compound action potential gets larger on warming, whereas in the presence of bumetanide and amiloride (blockers of electroneutral Na+ movement), the action potential amplitude consistently falls. This suggests a warming‐induced hyperpolarization that is reduced by blocking electroneutral Na+ movement. In the presence of ouabain, the action potential collapses. This collapse is speeded by warming, and exposure to bumetanide and amiloride slows the temperature‐dependent amplitude decline, consistent with a warming‐induced increase in electroneutral Na+ entry. Blocking electroneutral Na+ movement is predicted to be useful in the treatment of temperature‐dependent symptoms under conditions with reduced safety factor (Uhthoff's phenomenon) and provide a route to neuroprotection.
A new eriophyoid mite species, Diptilomiopus floridanus (Acari: Eriophyoidea: Diptilomiopidae), from citrus in Florida, USA
Authors: Craemer Charnie , Amrine James W Jr , Childers Carl C , Rogers Michael E. , Achor Diann S.
Published: February 2017

A new eriophyoid mite species, Diptilomiopus floridanus sp. nov., (Eriophyoidea: Diptilomiopidae) is described and illustrated from various Citrus spp. in Florida, USA. This is the second Diptilomiopus sp. known on citrus worldwide and the third on plants of Rutaceae. A key is provided for six Diptilomiopus spp. including the new species.
Age-associated molecular changes are deleterious and may modulate life span through diet
Authors: Lee Sang-Goo , Kaya Alaattin , Avanesov Andrei S. , Podolskiy Dmitriy I. , Song Eun Ju , Go Du-Min , Jin Gwi-Deuk , Hwang Jae Yeon , Kim Eun Bae , Kim Dae-Yong , Gladyshev Vadim N.
Published: February 2017

Age-associated molecular changes are deleterious and causally linked with aging and may affect life span through diet.
Combining contact tracing with targeted indoor residual spraying significantly reduces dengue transmission
Authors: Vazquez-Prokopec Gonzalo M. , Montgomery Brian L. , Horne Peter , Clennon Julie A. , Ritchie Scott A.
Published: February 2017

Pairing location-based contact tracing and targeted indoor insecticide applications can effectively prevent dengue transmission.
Scaffolding bacterial genomes and probing host-virus interactions in gut microbiome by proximity ligation (chromosome capture) assay
Authors: Marbouty Martial , Baudry Lyam , Cournac Axel , Koszul Romain
Published: February 2017

Two proximity ligation approaches are used to probe the gut’s phage-bacteria infection network using Meta3C and GRAAL scaffolding.
Impact of surface roughness on liquid-liquid transition
Authors: Murata Ken-ichiro , Tanaka Hajime
Published: February 2017

A surface rubbing treatment is found to accelerate liquid-liquid transition in a single-component molecular liquid.
Successive annual influenza vaccination induces a recurrent oligoclonotypic memory response in circulating T follicular helper cells
Authors: Herati Ramin Sedaghat , Muselman Alexander , Vella Laura , Bengsch Bertram , Parkhouse Kaela , Del Alcazar Daniel , Kotzin Jonathan , Doyle Susan A. , Tebas Pablo , Hensley Scott E. , Su Laura F. , Schmader Kenneth E. , Wherry E. John
Published: February 2017

Influenza vaccination induced a circulating T
FH
response involving influenza-specific memory T cell receptor clonotypes.
Functional Characterization of a 28-Kilobase Catabolic Island from Pseudomonas sp. Strain M1 Involved in Biotransformation of β-Myrcene and Related Plant-Derived Volatiles
Authors: Soares-Castro Pedro , Montenegro-Silva Pedro , Heipieper Hermann J. , Santos Pedro M.
Published: February 2017

Pseudomonas
sp. strain M1 is able to mineralize highly hydrophobic and recalcitrant compounds, such as benzene, phenol, and their methylated/halogenated derivatives, as well as the backbone of several monoterpenes. The ability to use such a spectrum of compounds as the sole carbon source is, most probably, associated with a genetic background evolved under different environmental constraints. The outstanding performance of strain M1 regarding β-myrcene catabolism was elucidated in this work, with a focus on the biocatalytical potential of the β-myrcene-associated core code, comprised in a 28-kb genomic island (GI), predicted to be organized in 8 transcriptional units. Functional characterization of this locus with promoter probes and analytical approaches validated the genetic organization predicted
in silico
and associated the β-myrcene-induced promoter activity to the production of β-myrcene derivatives. Notably, by using a whole-genome mutagenesis strategy, different genotypes of the 28-kb GI were generated, resulting in the identification of a novel putative β-myrcene hydroxylase, responsible for the initial oxidation of β-myrcene into myrcen-8-ol, and a sensor-like regulatory protein, whose inactivation abolished the
myr

+

trait of M1 cells. Moreover, it was demonstrated that the range of monoterpene substrates of the M1 enzymatic repertoire, besides β-myrcene, also includes other acyclic (e.g., β-linalool) and cyclic [e.g.,
R
-(+)-limonene and (−)-β-pinene] molecules. Our findings are the cornerstone for following metabolic engineering approaches and hint at a major role of the 28-kb GI in the biotransformation of a broad monoterpene backbone spectrum for its future biotechnological applications.

IMPORTANCE
Information regarding microbial systems able to biotransform monoterpenes, especially β-myrcene, is limited and focused mainly on nonsystematic metabolite identification. Complete and detailed knowledge at the genetic, protein, metabolite, and regulatory levels is essential in order to set a model organism or a catabolic system as a biotechnology tool. Moreover, molecular characterization of reported systems is scarce, almost nonexistent, limiting advances in the development of optimized cell factories with strategies based on the new generation of metabolic engineering platforms. This study provides new insights into the intricate molecular functionalities associated with β-myrcene catabolism in
Pseudomonas
, envisaging the production of a molecular knowledge base about the underlying catalytic and regulatory mechanisms of plant-derived volatile catabolic pathways.
Ketoacylsynthase Domains of a Polyunsaturated Fatty Acid Synthase in Thraustochytrium sp. Strain ATCC 26185 Can Effectively Function as Stand-Alone Enzymes in Escherichia coli
Authors: Xie Xi , Meesapyodsuk Dauenpen , Qiu Xiao
Published: February 2017

Thraustochytriumsp. strain ATCC 26185 accumulates a high level of docosahexaenoic acid (DHA), a nutritionally important ω-3 very-long-chain polyunsaturated fatty acid (VLCPUFA) synthesized primarily by polyunsaturated fatty acid (PUFA) synthase, a type I polyketide synthase-like megaenzyme. The PUFA synthase in this species comprises three large subunits, each with multiple catalytic domains. It was hypothesized that among these domains, ketoacylsynthase (KS) domains might be critical for catalyzing the condensation of specific unsaturated acyl-acyl carrier proteins (ACPs) with malonyl-ACP, thereby retaining double bonds in an extended acyl chain. To investigate the functions of these putative KS domains, two segment sequences from subunit A (KS-A) and subunit B (KS-B) of the PUFA synthase were dissected and then expressed as stand-alone enzymes inEscherichia coli. The results showed that both KS-A and KS-B domains could complement the defective phenotypes of bothE. colifabBandfabFmutants. Overexpression of these domains in wild-typeE. coliled to increases in total fatty acid production. KS-B produced a higher ratio of unsaturated fatty acids (UFAs) to saturated fatty acids (SFAs), while KS-A could improve the overall production of fatty acids more effectively, particularly for the production of SFAs, implying that KS-A is more comparable to FabF, while KS-B is more similar to FabB in catalytic functions. Successful complementation and functional expression of the embedded KS domains inE. coliare the first step forward in studying the molecular mechanism of the PUFA synthase for the biosynthesis of VLCPUFAs inThraustochytrium.

IMPORTANCEVery-long-chain polyunsaturated fatty acids (VLCPUFAs) are important for human health. They can be biosynthesized in either an aerobic pathway or an anaerobic pathway in nature. However, abundant VLCPUFAs in marine microorganisms are primarily synthesized by polyunsaturated fatty acid (PUFA) synthase, a megaenzyme with multiple subunits, each with multiple catalytic domains. Furthermore, the fundamental mechanism for this enzyme to synthesize these fatty acids still remains unknown. This report started with dissecting the embedded KS domains of the PUFA synthase from marine protistThraustochytriumsp. strain ATCC 26185 and then expressing them in wild-typeE. coliand mutants defective in condensation of acyl-ACP with malonyl-ACP. Successful complementation of the mutants and improved fatty acid production in the overexpression experiments indicate that these KS domains can effectively function as stand-alone enzymes inE. coli. This result has paved the way for further studying of molecular mechanisms of the PUFA synthase for the biosynthesis of VLCPUFAs.
Physical and Functional Interplay between MazF
1
Bif
and Its Noncognate Antitoxins from Bifidobacterium longum
Authors: Wei Yanxia , Li Yang , Yang Fan , Wu Qiong , Liu Dianbin , Li Xiangyang , Hua Hui , Liu Xiaomei , Wang Yugang , Zheng Kuiyang , Tang Renxian
Published: February 2017

Bifidobacterium longum
strain JDM301, a widely used commercial strain in China, encodes at least two MazEF-like modules and one RelBE-like toxin-antitoxin (TA) system in its chromosome, designated MazE
1
F
1
Bif
, MazE
2
F
2
Bif
, and RelBE
Bif
, respectively. Bacterial TA systems play an important role in several stress responses, but the relationship between these TA systems is largely unknown. In this study, the interactions between MazF
1
Bif
and MazE
2
Bif
or RelB
Bif
were assessed in
B. longum
strain JDM301. MazF
1
Bif
caused the degradation of
tufA
Bif
mRNA, and its toxicity was inhibited by forming a protein complex with its cognate antitoxin, MazE
1
Bif
. Notably, MazF
1
Bif
toxicity was also partially neutralized when jointly expressed with noncognate antitoxin MazE
2
Bif
or RelB
Bif
. Our results show that the two noncognate antitoxins also inhibited mRNA degradation caused by MazF
1
Bif
toxin. Furthermore, the physical interplay between MazF
1
Bif
and its noncognate antitoxins was confirmed by immunoprecipitation. These results suggest that MazF
1
Bif
can arrest cell growth and that MazF
1
Bif
toxicity can be neutralized by its cognate and noncognate antitoxins. These results imply that JDM301 uses a sophisticated toxin-antitoxin interaction network to alter its physiology when coping with environmental stress.

IMPORTANCE
Although toxin-antitoxin (TA) systems play an important role in several stress responses, the regulatory mechanisms of multiple TA system homologs in the bacterial genome remain largely unclear. In this study, the relationships between MazE
1
F
1
Bif
and the other two TA systems of
Bifidobacterium longum
strain JDM301 were explored, and the interactions between MazF
1
Bif
and MazE
2
Bif
or RelB
Bif
were characterized. In addition, the mRNA degradation activity of MazF
1
Bif
was demonstrated. In particular, the interaction of the toxin with noncognate antitoxins was shown, even between different TA families (MazF
1
Bif
toxin and RelB
Bif
antitoxin) in JDM301. This work provides insight into the regulatory mechanisms of TA systems implicated in the stress responses of bifidobacteria.
Accurate Quantification of Laminarin in Marine Organic Matter with Enzymes from Marine Microbes
Authors: Becker Stefan , Scheffel André , Polz Martin F. , Hehemann Jan-Hendrik
Published: February 2017

Marine algae produce a variety of glycans, which fulfill diverse biological functions and fuel the carbon and energy demands of heterotrophic microbes. A common approach to analysis of marine organic matter uses acid to hydrolyze the glycans into measurable monosaccharides. The monosaccharides may be derived from different glycans that are built with the same monosaccharides, however, and this approach does not distinguish between glycans in natural samples. Here we use enzymes to digest selectively and thereby quantify laminarin in particulate organic matter. Environmental metaproteome data revealed carbohydrate-active enzymes from marine flavobacteria as tools for selective hydrolysis of the algal β-glucan laminarin. The enzymes digested laminarin into glucose and oligosaccharides, which we measured with standard methods to establish the amounts of laminarin in the samples. We cloned, expressed, purified, and characterized three new glycoside hydrolases (GHs) of
Formosa
bacteria: two are endo-β-1,3-glucanases, of the GH16 and GH17 families, and the other is a GH30 exo-β-1,6-glucanase.
Formosa
sp. nov strain Hel1_33_131 GH30 (FbGH30) removed the β-1,6-glucose side chains, and
Formosa agariphila
GH17A (FaGH17A) and FaGH16A hydrolyzed the β-1,3-glucose backbone of laminarin. Specificity profiling with a library of glucan oligosaccharides and polysaccharides revealed that FaGH17A and FbGH30 were highly specific enzymes, while FaGH16A also hydrolyzed mixed-linked glucans with β-1,4-glucose. Therefore, we chose the more specific FaGH17A and FbGH30 to quantify laminarin in two cultured diatoms, namely,
Thalassiosira weissflogii
and
Thalassiosira pseudonana
, and in seawater samples from the North Sea and the Arctic Ocean. Combined, these results demonstrate the potential of enzymes for faster, stereospecific, and sequence-specific analysis of select glycans in marine organic matter.

IMPORTANCE
Marine algae synthesize substantial amounts of the glucose polymer laminarin for energy and carbon storage. Its concentrations, rates of production by autotrophic organisms, and rates of digestion by heterotrophic organisms remain unknown. Here we present a method based on enzymes that hydrolyze laminarin and enable its quantification even in crude substrate mixtures, without purification. Compared to the commonly used acid hydrolysis, the enzymatic method presented here is faster and stereospecific and selectively cleaves laminarin in mixtures of glycans, releasing only glucose and oligosaccharides, which can be easily quantified with reducing sugar assays.
Environmental Surveillance of Norovirus Genogroups I and II for Sensitive Detection of Epidemic Variants
Authors: Kazama Shinobu , Miura Takayuki , Masago Yoshifumi , Konta Yoshimitsu , Tohma Kentaro , Manaka Takafumi , Liu Xiaofang , Nakayama Daisuke , Tanno Takashi , Saito Mayuko , Oshitani Hitoshi , Omura Tatsuo
Published: February 2017

Sewage samples have been investigated to study the norovirus concentrations in sewage or the genotypes of noroviruses circulating in human populations. However, the statistical relationship between the concentration of the virus and the number of infected individuals and the clinical importance of genotypes or strains detected in sewage are unclear. In this study, we carried out both environmental and clinical surveillance of noroviruses for 3 years, 2013 to 2016. We performed cross-correlation analysis of the concentrations of norovirus GI or GII in sewage samples collected weekly and the reported number of gastroenteritis cases. Norovirus genotypes in sewage were also analyzed by pyrosequencing and compared with those identified in stool samples. The cross-correlation analysis found the peak coefficient (
R
= 0.51) at a lag of zero, indicating that the variation in the GII concentration, expressed as the log
10
number of copies per milliliter, was coincident with that in the gastroenteritis cases. A total of 15 norovirus genotypes and up to 8 genotypes per sample were detected in sewage, which included all of the 13 genotypes identified in the stool samples except 2. GII.4 was most frequently detected in both sample types, followed by GII.17. Phylogenetic analysis revealed that a strain belonging to the GII.17 Kawasaki 2014 lineage had been introduced into the study area in the 2012-2013 season. An increase in GI.3 cases was observed in the 2015-2016 season, and sewage monitoring identified the presence of GI.3 in the previous season (2014-2015). Our results demonstrated that monitoring of noroviruses in sewage is useful for sensitive detection of epidemic variants in human populations.

IMPORTANCE
We obtained statistical evidence of the relationship between the variation in the norovirus GII concentration in sewage and that of gastroenteritis cases during the 3-year study period. Sewage sample analysis by a pyrosequencing approach enabled us to understand the temporal variation in the norovirus genotypes circulating in human populations. We found that a strain closely related to the GII.17 Kawasaki 2014 lineage had been introduced into the study area at least 1 year before its appearance and identification in clinical cases. A similar pattern was observed for GI.3; cases were reported in the 2015-2016 season, and closely related strains were found in sewage in the previous season. Our observation indicates that monitoring of noroviruses in sewage is useful for the rapid detection of an epidemic and is also sensitive enough to study the molecular epidemiology of noroviruses. Applying this approach to other enteric pathogens in sewage will enhance our understanding of their ecology.
Unique Strain of Rickettsia parkeri Associated with the Hard Tick Dermacentor parumapertus Neumann in the Western United States
Authors: Paddock Christopher D. , Allerdice Michelle E. J. , Karpathy Sandor E. , Nicholson William L. , Levin Michael L. , Smith Travis C. , Becker Tom , Delph Robert J. , Knight Robert N. , Ritter Jana M. , Sanders Jeanine H. , Goddard Jerome
Published: February 2017

In 1953, investigators at the Rocky Mountain Laboratories in Hamilton, MT, described the isolation of a spotted fever groupRickettsia(SFGR) species fromDermacentor parumapertusticks collected from black-tailed jackrabbits (Lepus californicus) in northern Nevada. Several decades later, investigators characterized this SFGR (designated the parumapertus agent) by using mouse serotyping methods and determined that it represented a distinct rickettsial serotype closely related toRickettsia parkeri; nonetheless, the parumapertus agent was not further characterized or studied. To our knowledge, no isolates of the parumapertus agent remain in any rickettsial culture collection, which precludes contemporary phylogenetic placement of this enigmatic SFGR. To rediscover the parumapertus agent, adult-stageD. parumapertusticks were collected from black-tailed jackrabbits shot or encountered as roadkills in Arizona, Utah, or Texas from 2011 to 2016. A total of 339 ticks were collected and evaluated for infection withRickettsiaspecies. Of 112D. parumapertusticks collected in south Texas, 16 (14.3%) contained partialompAsequences with the closest identity (99.6%) toRickettsiasp. strain Atlantic rainforest Aa46, an SFGR that is closely related or identical to an SFGR species that causes a mild rickettsiosis in several states of Brazil. A pure isolate, designated strain Black Gap, was cultivated in Vero E6 cells, and sequence analysis of therrs,gltA,sca0,sca5, andsca4genes also revealed the closest genetic identity toRickettsiasp. Atlantic rainforest Aa46. Phylogenetic analysis of the five concatenated rickettsial genes placeRickettsiasp. strain Black Gap andRickettsiasp. Atlantic rainforest Aa46 withR. parkeriin a distinct and well-supported clade.

IMPORTANCEWe suggest thatRickettsiasp. Black Gap andRickettsiasp. Atlantic rainforest Aa46 represent nearly identical strains ofR. parkeriand thatRickettsiasp. Black Gap or a very similar strain ofR. parkerirepresents the parumapertus agent. The close genetic relatedness among these taxa, as well as the response of guinea pigs infected with the Black Gap strain, suggests thatR. parkeriBlack Gap could cause disease in humans. The identification of this organism could also account, at least in part, for the remarkable differences in severity ascribed to Rocky Mountain spotted fever (RMSF) among various regions of the American West during the early 20th century. We suggest that the wide variation in case fatality rates attributed to RMSF could have occurred by the inadvertent inclusion of cases of milder disease caused byR. parkeriBlack Gap.
Critical Concentration of Lecithin Enhances the Antimicrobial Activity of Eugenol against Escherichia coli
Authors: Zhang Haoshu , Dudley Edward G. , Davidson P. Michael , Harte Federico
Published: February 2017

Lecithin is a natural emulsifier used in a wide range of food and nonfood applications to improve physical stability, with no known bioactive effects. In this study, the effect of lecithin on the antimicrobial performance of a constant eugenol concentration was tested against three
Escherichia coli
strains (C600, 0.1229, and O157:H7 strain ATCC 700728). This is the first study, to our knowledge, focusing on lecithin at concentrations below those commonly used in foods to improve the stability of oil in water emulsions (≤10 mg/100 ml). For all three cultures, significant synergistic antimicrobial effects were observed when
E. coli
cultures were exposed to a constant eugenol concentration (ranging from 0.043 to 0.050% [wt/wt]) together with critical lecithin concentrations ranging from 0.5 to 1 mg/100 ml. Increasing the concentration of lecithin above 1 mg/100 ml (up to 10 mg/100 ml lecithin) diminished the antibacterial effect to values similar to those with eugenol-only treatments. The formation of aggregates (<100 nm) at the critical lecithin concentration was observed using cryo-transmission electron microscopy (cryo-TEM), together with a reduction in light absorbance at 284 nm. At critically low concentrations of lecithin, the formation of nanoscale aggregates is responsible for improving eugenol antimicrobial effects.

IMPORTANCE
Essential oils (EOs) are effective natural antimicrobials. However, their hydrophobicity and strong aromatic character limit the use of essential oils in food systems. Emulsifiers (e.g., lecithin) increase the stability of EOs in water-based systems but fail to consistently improve antimicrobial effects. We demonstrate that lecithin, within a narrow critical concentration window, can enhance the antimicrobial properties of eugenol. This study highlights the potential bioactivity of lecithin when utilized to effectively control foodborne pathogens.