bluuebunny/crossref_metadata_2025 huggingface dataset:
Cognitive control and conflict adaptation in youth with high‐functioning autism
Authors: Larson Michael J. , South Mikle , Clayson Peter E. , Clawson Ann
Published: December 2011

Background:  Youth diagnosed with autism spectrum disorders (ASD) often show deficits in cognitive control processes, potentially contributing to characteristic difficulties monitoring and regulating behavior. Modification of performance following conflict can be measured by examining conflict adaptation, the adjustment of cognitive resources based on previous‐trial conflict. The electrophysiological correlates of these processes can be measured using the N2, a stimulus‐locked component of the event‐related potential (ERP).

Methods:  High‐density ERPs and behavioral data [i.e. response times (RTs) and error rates] were acquired while 28 youth with ASD and 36 typically developing controls completed a modified Eriksen flanker task.

Results:  Behaviorally, groups showed similar conflict adaptation effects; youth with ASD showed larger RT slowing on switch trials. For electrophysiology, controls demonstrated larger N2 amplitudes for incongruent (high‐conflict) trials following congruent (low‐conflict) trials than for incongruent trials following incongruent trials. Importantly, youth with ASD showed no such differences in N2 amplitude based on previous‐trial conflict.

Conclusions:  Lack of electrophysiological conflict adaptation effects in youth with ASD indicates irregular neural processing associated with conflict adaptation. Individuals with ASD show declines in level of conflict evaluation and adaptation. Future research is necessary to accurately characterize and understand the behavioral implications of these cognitive control deficits relative to diagnostic severity, anxiety, and personality.
Understanding desisting and persisting forms of delinquency: the unique contributions of disruptive behavior disorders and interpersonal callousness
Authors: Byrd Amy L. , Loeber Rolf , Pardini Dustin A.
Published: December 2011

Background:  While associations between conduct disorder (CD), oppositional defiant disorder (ODD), attention deficit hyperactivity disorder (ADHD), and interpersonal callousness (IC) symptoms and delinquency onset are well established, less is known about whether these characteristics differentiate desisting and persisting delinquency. The current study examined whether childhood and adolescent CD, ODD, ADHD, and IC symptoms uniquely distinguished boys who exhibited persisting versus desisting delinquency from adolescence into adulthood.

Methods:  Participants were 503 boys (57% African American) repeatedly assessed from ages 7 to 25. Associations between childhood and adolescent CD, ODD, ADHD, and IC symptoms and desisting and persisting delinquency were examined independently and after controlling for their co‐occurrence and multiple covariates.

Results:  Conduct disorder and IC symptoms in childhood and adolescence were higher among boys whose delinquency persisted into adulthood relative to those boys whose delinquency desisted across time. After controlling for the overlap between symptoms of ADHD, ODD, CD and IC, only adolescent CD and IC symptoms emerged as unique predictors of the differentiation between persisters and desisters. Moreover, adolescent CD and IC symptoms continued to contribute unique variance even after childhood levels of these characteristics were accounted for.

Conclusions:  Boys with elevated levels of CD and IC symptoms in childhood and adolescence are at risk for exhibiting a pattern of delinquency that persists from adolescence into adulthood. Intervention efforts designed to prevent chronic delinquency should target youth with co‐occurring CD and IC symptoms in childhood and adolescence.
Journalists’ views about reporting avian influenza and a potential pandemic: a qualitative study
Authors: Hooker Claire , King Catherine , Leask Julie
Published: December 2011

Please cite this paper as: Hooker et al. (20XX) Journalists’ views about reporting avian influenza and a potential pandemic: a qualitative study. Influenza and Other Respiratory Viruses 6(3), 224–229.

Background  The mass media is a key component of any public communication strategy for influenza or other respiratory illnesses, but coverage can be variable. In this study, we explored the factors that influenced journalists’ coverage of avian influenza as a model for coverage of a potential influenza pandemic.

Methods  This study involved semi‐structured interviews with 16 journalists from major Australian print, radio and television media organisations reporting on avian influenza and pandemic planning. Journalists, including reporters, editors and producers, were interviewed between October 2006 and August 2007. Thematic analysis was used to draw out major lessons for health communicators.

Results  Coverage of avian influenza was influenced by a small set of news values: catastrophic potential, cultural and geographical proximity, unfamiliarity and uncertainty. Lack of novelty and the absence of compelling images led to a decline in coverage. Journalists expressed concerns about the accuracy and impacts of reporting, but saw as critically important, their primary role as informants. They hence emphasised the importance of journalistic independence. Journalists all intended to continue working in a pandemic.

Conclusions  Health experts need to adapt their timetables and resources to journalists’ needs to improve their mutual communication. In crisis situations, journalists communicate with the public efficiently and effectively, but expert and journalistic views on the role and content of coverage may diverge in the post‐acute, reflective phase of a crisis.
Your work is interfering with our life! The influence of a significant other on employee job search activity
Authors: Baskerville Watkins Marla , Ren Run , Boswell Wendy R. , Umphress Elizabeth E. , Triana María del Carmen , Zardkoohi Asghar
Published: December 2011

This research draws on family systems theory to examine the influence of the significant other on employees’ job search behaviours. Data from 102 matched pairs of employees and their significant others showed that significant others’ perception of the employee's work‐to‐family conflict was positively related to the employee's job search activity after controlling for employee self‐reported work‐to‐family conflict. Contributions and implications are discussed.
Vascular adaptation in athletes: is there an ‘athlete's artery’?
Authors: Green Daniel J. , Spence Angela , Rowley Nicola , Thijssen Dick H. J. , Naylor Louise H.
Published: December 2011

Whilst the existence of a specific phenotype characterized as ‘athlete's heart’ is generally acknowledged, the question of whether athletes exhibit characteristic vascular adaptations has not been specifically addressed. To do so in this symposium, studies which have assessed the size, wall thickness and function of elastic, large muscular and smaller resistance arteries in athletes have been reviewed. Notwithstanding the caveats pertaining to cross‐sectional comparisons between athletes and ‘matched’ control subjects, these studies reveal increased conduit artery size, including enlargement of epicardial arteries and those supplying skeletal muscle. Evidence that peak limb blood flow responses are enhanced in athletes further suggests that resistance arteries undergo increases in total cross‐sectional area. Such increases can be localized to those arteries supplying active muscle leading to speculation, supported by exercise training studies in humans and animal and cellular data, that arterial enlargement is associated with repetitive episodic increases in arterial shear stress which elicit endothelium‐mediated remodelling. Such structural remodelling at conduit and resistance artery level may play a role in accommodating the substantial increase in cardiac output apparent in endurance athletes; arterial pressure is not increased at rest or during exercise in athletes (versus control subjects). Arterial wall remodelling also occurs in athletes but, in contrast to the impact of shear stress on remodelling of arterial lumenal dimensions, the impact of endurance athletic status on wall thickness may be a systemic, rather than localized, phenomenon. Finally, the question of whether the arteries of athletes exhibit enhanced function is moot. Somewhat paradoxically, measures of conduit and resistance artery endothelial function may not be enhanced, compared with healthy control subjects. This may relate to the inherent difficulty of improving arterial function which is already normal, or the time course and transient nature of functional change. It may also relate to the impact of compensatory structural remodelling, as arterial lumen size and wall thickness both affect functional responsiveness. In summary, there is clear evidence for an impact of athletic status on arterial structure and function, at least with respect to the impact of endurance training. Arterial adaptation may, to some extent, emulate that evident in the hearts of endurance athletes, and it is tempting to speculate that similar mechanisms may be at play.
Lateral septal area α1‐ and α2‐adrenoceptors differently modulate baroreflex activity in unanaesthetized rats
Authors: Scopinho América A. , Alves Fernando H. F. , Resstel Leonardo B. M. , Correa Fernando M. A. , Crestani Carlos C.
Published: December 2011

The lateral septal area (LSA) is a limbic structure involved in autonomic, neuroendocrine and behavioural responses. An inhibitory influence of the LSA on baroreflex activity has been reported; however, the local neurotransmitter involved in this modulation is still unclear. In the present study, we verified the involvement of local LSA adrenoceptors in modulating cardiac baroreflex activity in unanaesthetized rats. Bilateral microinjection of the selective α1‐adrenoceptor antagonist WB4101 (10 nmol in a volume of 100 nl) into the LSA decreased baroreflex bradycardia evoked by blood pressure increases, but had no effect on reflex tachycardia evoked by blood pressure decreases. Nevertheless, bilateral administration of the selective α2‐adrenoceptor antagonist RX821002 (10 nmol in 100 nl) increased baroreflex tachycardia without affecting reflex bradycardia. Treatment of the LSA with a cocktail containing WB4101 and RX821002 decreased baroreflex bradycardia and increased reflex tachycardia. The non‐selective β‐adrenoceptor antagonist propranolol (10 nmol in 100 nl) did not affect either reflex bradycardia or tachycardia. Microinjection of noradrenaline into the LSA increased reflex bradycardia and decreased the baroreflex tachycardic response, an opposite effect compared with those observed after double blockade of α1‐ and α2‐adrenoceptors, and this effect of noradrenaline was blocked by local LSA pretreatment with the cocktail containing WB4101 and RX821002. The present results provide advances in our understanding of the baroreflex neural circuitry. Taken together, data suggest that local LSA α1‐ and α2‐adrenoceptors modulate baroreflex control of heart rate differently. Data indicate that LSA α1‐adrenoceptors exert a facilitatory modulation on baroreflex bradycardia, whereas local α2‐adrenoceptors exert an inhibitory modulation on reflex tachycardia.
Heavy and moderate interval exercise training alters low‐flow‐mediated constriction but does not increase circulating progenitor cells in healthy humans
Authors: Rakobowchuk Mark , Harris Emma , Taylor Annabelle , Baliga Vivek , Cubbon Richard M. , Rossiter Harry B. , Birch Karen M.
Published: December 2011

Moderate‐intensity endurance exercise training improves vascular endothelial vasomotor function; however, the impact of high‐intensity exercise training has been equivocal. Thus, the effect of the physiological stress of the exercise remains poorly understood. Furthermore, enhanced vascular repair mediated by circulating progenitor cells may also be improved. To address whether the physiological stress of exercise training is an important factor contributing to these adaptations, 20 healthy participants trained for 6 weeks. Training involved either moderate (MSIT; n= 9) or heavy metabolic stress (HSIT; n= 11) interval exercise training programmes matched for total work and duration of exercise. Before and after training, flow‐mediated dilatation, low‐flow‐mediated constriction and total vessel reactivity were measured at the brachial artery using Doppler ultrasound. Circulating progenitor cells (CD34+, CD133+ and CD309/KDR+) were measured by flow cytometry (means ± SD). Relative (MSIT pre‐ 5.5 ± 3.4 versus post‐training 6.6 ± 2.5%; HSIT pre‐ 6.6 ± 4.1 versus post‐training 7.0 ± 3.4%, P= 0.33) and normalized (P= 0.16) flow‐mediated dilatation did not increase with either training programme. However, low‐flow‐mediated constriction was greater after training in both groups (MSIT pre‐ −0.5 ± 3.2 versus post‐training −1.9 ± 3.1%; HSIT pre‐ −1.0 ± 1.7 versus post‐training −2.9 ± 3.0%, P= 0.04) and contributed to greater total vessel reactivity (MSIT pre‐ 7.4 ± 3.3 versus post‐training 10.1 ± 3.7%; HSIT pre‐ 10.9 ± 5.9 versus post‐training 12.7 ± 6.2%, P= 0.01). Peak reactive hyperaemia and the area under the shear rate curve were not different between groups, either before or after training. Although circulating progenitor cell numbers increased following heavy‐intensity interval exercise training, variability was great amongst participants [MSIT pre‐ 16 ± 18 versus post‐training 14 ± 12 cells (ml whole blood)−1; HSIT pre‐ 8 ± 6 versus post‐training 19 ± 23 cells (ml whole blood)−1, P= 0.50]. Overall, vasoconstrictor function may be augmented by moderate‐ and heavy‐intensity interval exercise training in young adults. However, circulating progenitor cell numbers were not increased, suggesting that these cells are not likely to be upregulated as a result of training.
Association of Different Genetic Types of Francisella-Like Organisms with the Rocky Mountain Wood Tick (Dermacentor andersoni) and the American Dog Tick (Dermacentor variabilis) in Localities Near Their Northern Distributional Limits
Authors: Dergousoff Shaun J. , Chilton Neil B.
Published: December 2011

Dermacentor andersoniandDermacentor variabilisfrom allopatric and sympatric populations near their northern distributional limits were examined for the presence ofFrancisellaspecies using molecular techniques that targeted 373 bp of the 16S rRNA gene. Although there was no evidence for the presence ofFrancisella tularensisin any tick,Francisella-like endosymbionts (FLEs) were common inD. andersoniandD. variabilisadults and immatures. A significantly greater proportion of female ticks contained FLEs compared to male ticks. In addition, significantly moreD. variabilisadult individuals contained multiple FLE sequence types than didD. andersoniadults. Ten different types of FLEs were identified based on the sequence data, which has implications for diagnostic tests and epidemiological studies ofF. tularensisin tick populations in Canada. The three most prevalent types of FLEs have been detected previously inD. andersoniorD. variabilisfrom other parts of their distributional ranges, whereas the other seven FLE types have not been reported previously. A comparison of the FLEs from both allopatric and sympatric populations of these two tick species provided insight into the relative host-specificity and the modes of transmission of these tick-borne bacteria. In general, each FLE type was specific for one tick species, suggesting vertical transmission of each bacterium. However, there were a few instances of potential cross-transfer of two FLE types to the other tick species at locations whereD. andersoniandD. variabilisoccurred in sympatry, suggesting that there may be occasional horizontal transmission of some FLEs.
AnagrQuorum Sensing System That Regulates Granulose Formation and Sporulation in Clostridium acetobutylicum
Authors: Steiner Elisabeth , Scott Jamie , Minton Nigel P. , Winzer Klaus
Published: December 2011

The Gram-positive, anaerobic, endospore-forming bacteriumClostridium acetobutylicumhas considerable biotechnological potential due to its ability to produce solvents as fermentation products, in particular the biofuel butanol. Its genome contains a putativeagrlocus,agrBDCA, known in staphylococci to constitute a cyclic peptide-based quorum sensing system. In staphylococci,agrBDis required for the generation of a peptide signal that, upon extracellular accumulation, is sensed by anagrCA-encoded two-component system. Using ClosTron technology,agrB,agrC, andagrAmutants ofC. acetobutylicumATCC 824 were generated and phenotypically characterized. Mutants and wild type displayed similar growth kinetics and no apparent differences in solvent formation under the conditions tested. However, the number of heat-resistant endospores formed by the mutants in liquid culture was reduced by about one order of magnitude. On agar-solidified medium, spore formation was more strongly affected, particularly inagrAandagrCmutants. Similarly, accumulation of the starch-like storage compound granulose was almost undetectable in colonies ofagrB,agrA, andagrCmutants. Importantly, these defects could be genetically complemented, demonstrating that they were directly linked toagrinactivation. A diffusible factor produced byagrBD-expressing strains was found to restore granulose and spore formation in theagrBmutant. Furthermore, a synthetic cyclic peptide, designed on the basis of theC. acetobutylicumAgrD sequence, was also capable of complementing the defects of theagrBmutant when added exogenously to the culture. Together, these findings support the hypothesis thatagr-dependent quorum sensing is involved in the regulation of sporulation and granulose formation inC. acetobutylicum.
Transcriptional Analysis of a Dehalococcoides-Containing Microbial Consortium Reveals Prophage Activation
Authors: Waller Alison S. , Hug Laura A. , Mo Kaiguo , Radford Devon R. , Maxwell Karen L. , Edwards Elizabeth A.
Published: December 2011

Chlorinated solvents are among the most prevalent groundwater contaminants in the industrialized world. Biodegradation with
Dehalococcoides
-containing mixed cultures is an effective remediation technology. To elucidate transcribed genes in a
Dehalococcoides
-containing mixed culture, a shotgun metagenome microarray was created and used to investigate gene transcription during vinyl chloride (VC) dechlorination and during starvation (no chlorinated compounds) by a microbial enrichment culture called KB-1. In both treatment conditions, methanol was amended as an electron donor. Subsequently, spots were sequenced that contained the genes most differentially transcribed between the VC-degrading and methanol-only conditions, as well as spots with the highest intensities. Sequencing revealed that during VC degradation
Dehalococcoides
genes involved in transcription, translation, metabolic energy generation, and amino acid and lipid metabolism and transport were overrepresented in the transcripts compared to the average
Dehalococcoides
genome. KB-1
rdh
A14
(
vcrA
) was the only reductive dehalogenase homologous (RDH) gene with higher transcript levels during VC degradation, while multiple RDH genes had higher transcript levels in the absence of VC. Numerous hypothetical genes from
Dehalococcoides
also had higher transcript levels in methanol-only treatments, indicating that many uncharacterized proteins are involved in cell maintenance in the absence of chlorinated substrates. In addition, microarray results prompted biological experiments confirming that electron acceptor limiting conditions activated a
Dehalococcoides
prophage. Transcripts from
Spirochaetes
,
Chloroflexi
,
Geobacter
, and methanogens demonstrate the importance of non-
Dehalococcoides
organisms to the culture, and sequencing of identified shotgun clones of interest provided information for follow-on targeted studies.
Denitrifying Bacteria from the Genus Rhodanobacter Dominate Bacterial Communities in the Highly Contaminated Subsurface of a Nuclear Legacy Waste Site
Authors: Green Stefan J. , Prakash Om , Jasrotia Puja , Overholt Will A. , Cardenas Erick , Hubbard Daniela , Tiedje James M. , Watson David B. , Schadt Christopher W. , Brooks Scott C. , Kostka Joel E.
Published: December 2011

The effect of long-term mixed-waste contamination, particularly uranium and nitrate, on the microbial community in the terrestrial subsurface was investigated at the field scale at the Oak Ridge Integrated Field Research Challenge (ORIFRC) site in Oak Ridge, TN. The abundance, community composition, and distribution of groundwater microorganisms were examined across the site during two seasonal sampling events. At representative locations, subsurface sediment was also examined from two boreholes, one sampled from the most heavily contaminated area of the site and another from an area with low contamination. A suite of DNA- and RNA-based molecular tools were employed for community characterization, including quantitative PCR of rRNA and nitrite reductase genes, community composition fingerprinting analysis, and high-throughput pyrotag sequencing of rRNA genes. The results demonstrate that pH is a major driver of the subsurface microbial community structure and that denitrifying bacteria from the genus
Rhodanobacter
(class
Gammaproteobacteria
) dominate at low pH. The relative abundance of bacteria from this genus was positively correlated with lower-pH conditions, and these bacteria were abundant and active in the most highly contaminated areas. Other factors, such as the concentration of nitrogen species, oxygen level, and sampling season, did not appear to strongly influence the distribution of
Rhodanobacter
bacteria. The results indicate that these organisms are acid-tolerant denitrifiers, well suited to the acidic, nitrate-rich subsurface conditions, and pH is confirmed as a dominant driver of bacterial community structure in this contaminated subsurface environment.
Dead or Alive: Deformed Wing Virus and Varroa destructor Reduce the Life Span of Winter Honeybees
Authors: Dainat Benjamin , Evans Jay D. , Chen Yan Ping , Gauthier Laurent , Neumann Peter
Published: December 2011

Elevated winter losses of managed honeybee colonies are a major concern, but the underlying mechanisms remain controversial. Among the suspects are the parasitic mite
Varroa destructor
, the microsporidian
Nosema ceranae
, and associated viruses. Here we hypothesize that pathogens reduce the life expectancy of winter bees, thereby constituting a proximate mechanism for colony losses. A monitoring of colonies was performed over 6 months in Switzerland from summer 2007 to winter 2007/2008. Individual dead workers were collected daily and quantitatively analyzed for deformed wing virus (DWV), acute bee paralysis virus (ABPV),
N. ceranae
, and expression levels of the
vitellogenin
gene as a biomarker for honeybee longevity. Workers from colonies that failed to survive winter had a reduced life span beginning in late fall, were more likely to be infected with DWV, and had higher DWV loads. Colony levels of infection with the parasitic mite
Varroa destructor
and individual infections with DWV were also associated with reduced honeybee life expectancy. In sharp contrast, the level of
N. ceranae
infection was not correlated with longevity. In addition,
vitellogenin
gene expression was significantly positively correlated with ABPV and
N. ceranae
loads. The findings strongly suggest that
V. destructor
and DWV (but neither
N. ceranae
nor ABPV) reduce the life span of winter bees, thereby constituting a parsimonious possible mechanism for honeybee colony losses.
Anaerobic Degradation of 4-Methylbenzoate by a Newly Isolated Denitrifying Bacterium, Strain pMbN1
Authors: Lahme Sven , Harder Jens , Rabus Ralf
Published: December 2011

A novel alphaproteobacterium isolated from freshwater sediments, strain pMbN1, degrades 4-methylbenzoate to CO
2
under nitrate-reducing conditions. While strain pMbN1 utilizes several benzoate derivatives and other polar aromatic compounds, it cannot degrade
p
-xylene or other hydrocarbons. Based on 16S rRNA gene sequence analysis, strain pMbN1 is affiliated with the genus
Magnetospirillum
.
Calcite Biomineralization by Bacterial Isolates from the Recently Discovered Pristine Karstic Herrenberg Cave
Authors: Rusznyák Anna , Akob Denise M. , Nietzsche Sándor , Eusterhues Karin , Totsche Kai Uwe , Neu Thomas R. , Frosch Torsten , Popp Jürgen , Keiner Robert , Geletneky Jörn , Katzschmann Lutz , Schulze Ernst-Detlef , Küsel Kirsten
Published: December 2011

Karstic caves represent one of the most important subterranean carbon storages on Earth and provide windows into the subsurface. The recent discovery of the Herrenberg Cave, Germany, gave us the opportunity to investigate the diversity and potential role of bacteria in carbonate mineral formation. Calcite was the only mineral observed by Raman spectroscopy to precipitate as stalactites from seepage water. Bacterial cells were found on the surface and interior of stalactites by confocal laser scanning microscopy. Proteobacteria dominated the microbial communities inhabiting stalactites, representing more than 70% of total 16S rRNA gene clones. Proteobacteria formed 22 to 34% of the detected communities in fluvial sediments, and a large fraction of these bacteria were also metabolically active. A total of 9 isolates, belonging to the genera
Arthrobacter
,
Flavobacterium
,
Pseudomonas
,
Rhodococcus
,
Serratia
, and
Stenotrophomonas
, grew on alkaline carbonate-precipitating medium. Two cultures with the most intense precipitate formation,
Arthrobacter sulfonivorans
and
Rhodococcus globerulus
, grew as aggregates, produced extracellular polymeric substances (EPS), and formed mixtures of calcite, vaterite, and monohydrocalcite.
R. globerulus
formed idiomorphous crystals with rhombohedral morphology, whereas
A. sulfonivorans
formed xenomorphous globular crystals, evidence for taxon-specific crystal morphologies. The results of this study highlighted the importance of combining various techniques in order to understand the geomicrobiology of karstic caves, but further studies are needed to determine whether the mineralogical biosignatures found in nutrient-rich media can also be found in oligotrophic caves.
Listeria monocytogenes Mutants with Altered Growth Phenotypes at Refrigeration Temperature and High Salt Concentrations
Authors: Burall Laurel S. , Laksanalamai Pongpan , Datta Atin R.
Published: December 2011

Listeria monocytogenes
can survive and grow in refrigerated temperatures and high-salt environments. In an effort to better understand the associated mechanisms, a library of ∼ 5,200 transposon mutants of LS411, a food isolate from the Jalisco cheese outbreak, were screened for their ability to grow in brain heart infusion (BHI) broth at 5°C or in the presence of 7% NaCl and two mutants with altered growth profiles were identified. The LS522 mutant has a transposon insertion between
secA2
and
iap
and showed a significant reduction in growth in BHI broth at 5°C and in the presence of 7% NaCl. Reverse transcriptase quantitative PCR (RT-qPCR) revealed a substantial reduction in the expression of
iap
. Additionally, a hypothetical gene (
met
), containing a putative
S
-adenosylmethionine-dependent methyltransferase domain, downstream of
iap
had downregulated expression. In-frame deletion mutants of
iap
and
met
were created in LS411. The LS560 (LS411
Δiap
) mutant showed reduced growth at 5°C and in the presence of 7% salt, confirming its role in cold and salt growth attenuation. Surprisingly, the LS655 (LS411 Δ
met
) mutant showed slightly increased growth during refrigeration, though no alteration was seen in salt growth relative to the wild-type strain. The LS527 mutant, containing an insertion 36 bp upstream of the
gbu
operon, showed reduced expression of the
gbu
transcript by RT-qPCR and also showed growth reduction at 5°C and in the presence of 7% salt. This attenuation was severely exacerbated when the mutant was grown under the combined stresses. Analysis of the
gbu
operon deletion mutant showed decreased growth in 7% salt and refrigeration, supporting the previously characterized role for this gene in cold and salt adaptation. These studies indicate the potential for an intricate relationship between environmental stress regulation and virulence in
L. monocytogenes
.
Characteristics of Spoilage-Associated Secondary Cucumber Fermentation
Authors: Franco Wendy , Pérez-Díaz Ilenys M. , Johanningsmeier Suzanne D. , McFeeters Roger F.
Published: December 2011

Secondary fermentations during the bulk storage of fermented cucumbers can result in spoilage that causes a total loss of the fermented product, at an estimated cost of $6,000 to $15,000 per affected tank. Previous research has suggested that such fermentations are the result of microbiological utilization of lactic acid and the formation of acetic, butyric, and propionic acids. The objectives of this study were to characterize the chemical and environmental conditions associated with secondary cucumber fermentations and to isolate and characterize potential causative microorganisms. Both commercial spoilage samples and laboratory-reproduced secondary fermentations were evaluated. Potential causative agents were isolated based on morphological characteristics. Two yeasts,
Pichia manshurica
and
Issatchenkia occidentalis
, were identified and detected most commonly concomitantly with lactic acid utilization. In the presence of oxygen, yeast metabolic activities lead to lactic acid degradation, a small decline in the redox potential (E
h
, Ag/AgCl, 3 M KCl) of the fermentation brines, and an increase in pH to levels at which bacteria other than the lactic acid bacteria responsible for the primary fermentation can grow and produce acetic, butyric, and propionic acids. Inhibition of these yeasts by allyl isothiocyanate (AITC) resulted in stabilization of the fermented medium, while the absence of the preservative resulted in the disappearance of lactic and acetic acids in a model system. Additionally, three Gram-positive bacteria,
Lactobacillus buchneri
, a
Clostridium
sp., and
Pediococcus ethanolidurans
, were identified as potentially relevant to different stages of the secondary fermentation. The unique opportunity to study commercial spoilage samples generated a better understanding of the microbiota and environmental conditions associated with secondary cucumber fermentations.
Validating Thermal Inactivation of Salmonella spp. in Fresh and Aged Chicken Litter
Authors: Kim Jinkyung , Diao Junshu , Shepherd Marion W. , Singh Randhir , Heringa Spencer D. , Gong Chao , Jiang Xiuping
Published: December 2011

Our results revealed that a 7-log reduction of
Salmonella
can be achieved by exposing fresh chicken litter for 80.5 to 100.8, 78.4 to 93.1, and 44.1 to 63 min at 70, 75, and 80°C, respectively, depending on initial moisture contents. However, the aged chicken litter requires more heat treatment.
Identification of an Enzyme System for Daidzein-to-Equol Conversion in Slackia sp. Strain NATTS
Authors: Tsuji Hirokazu , Moriyama Kaoru , Nomoto Koji , Akaza Hideyuki
Published: December 2011

An
Escherichia coli
library comprising 8,424 strains incorporating gene fragments of the equol-producing bacterium
Slackia
sp. strain NATTS was constructed and screened for
E. coli
strains having daidzein- and dihydrodaidzein (DHD)- metabolizing activity. We obtained 3 clones that functioned to convert daidzein to DHD and 2 clones that converted DHD to equol. We then sequenced the gene fragments inserted into plasmids contained by these 5 clones. All of the gene fragments were contiguous, encoding three open reading frames (ORF-1, -2, and -3). Analysis of
E. coli
strains containing an expression vector incorporating one of the
orf-1
,
-2
, or
-3
genes revealed that (i) the protein encoded by
orf
-
1
was involved in the conversion of
cis/trans-
tetrahydrodaidzein (
cis/trans-
THD) to equol, (ii) the protein encoded by
orf
-
2
was involved in the conversion of DHD to
cis/trans-
THD, and (iii) the protein encoded by
orf
-
3
was involved in the conversion of daidzein to DHD. ORF-1 had a primary amino acid structure similar to that of succinate dehydrogenase. ORF-2 was presumed to be an enzyme belonging to the short-chain dehydrogenase/reductase superfamily. ORF-3 was predicted to have 42% identity to the daidzein reductase of
Lactococcus
strain 20-92 and belonged to the NADH:flavin oxidoreductase family. These findings showed that the daidzein-to-equol conversion reaction in the
Slackia
sp. NATTS strain proceeds by the action of these three enzymes.
Global Transcriptomic and Proteomic Responses of Dehalococcoides ethenogenes Strain 195 to Fixed Nitrogen Limitation
Authors: Lee Patrick K. H. , Dill Brian D. , Louie Tiffany S. , Shah Manesh , VerBerkmoes Nathan C. , Andersen Gary L. , Zinder Stephen H. , Alvarez-Cohen Lisa
Published: December 2011

Bacteria of the genus
Dehalococcoides
play an important role in the reductive dechlorination of chlorinated ethenes. A systems-level approach was taken in this study to examine the global transcriptomic and proteomic responses of exponentially growing cells of
Dehalococcoides ethenogenes
strain 195 to fixed nitrogen limitation (FNL), as dechlorination activity and cell yield both decrease during FNL. As expected, the nitrogen-fixing (
nif
) genes were differentially upregulated in the transcriptome and proteome of strain 195 during FNL. Aside from the
nif
operon, a putative methylglyoxal synthase-encoding gene (DET1576), the product of which is predicted to catalyze the formation of the toxic electrophile methylglyoxal and is implicated in the uncoupling of anabolism from catabolism in bacteria, was strongly upregulated in the transcriptome and could potentially play a role in the observed growth inhibition during FNL. Carbon catabolism genes were generally downregulated in response to FNL, and a number of transporters were differentially regulated in response to nitrogen limitation, with some playing apparent roles in nitrogen acquisition, while others were associated with general stress responses. A number of genes related to the functions of nucleotide synthesis, replication, transcription, translation, and posttranslational modifications were also differentially expressed. One gene coding for a putative reductive dehalogenase (DET1545) and a number of genes coding for oxidoreductases, which have implications in energy generation and redox reactions, were also differentially regulated. Interestingly, most of the genes within the multiple integrated elements were not differentially expressed. Overall, this study elucidates the molecular responses of strain 195 to FNL and identifies differentially expressed genes that are potential biomarkers to evaluate environmental cellular nitrogen status.
Dissimilatory Reduction of Extracellular Electron Acceptors in Anaerobic Respiration
Authors: Richter Katrin , Schicklberger Marcus , Gescher Johannes
Published: December 2011

An extension of the respiratory chain to the cell surface is necessary to reduce extracellular electron acceptors like ferric iron or manganese oxides. In the past few years, more and more compounds were revealed to be reduced at the surface of the outer membrane of Gram-negative bacteria, and the list does not seem to have an end so far.Shewanellaas well asGeobacterstrains are model organisms to discover the biochemistry that enables the dissimilatory reduction of extracellular electron acceptors. In both cases,c-type cytochromes are essential electron-transferring proteins. They make the journey of respiratory electrons from the cytoplasmic membrane through periplasm and over the outer membrane possible. Outer membrane cytochromes have the ability to catalyze the last step of the respiratory chains. Still, recent discoveries provided evidence that they are accompanied by further factors that allow or at least facilitate extracellular reduction. This review gives a condensed overview of our current knowledge of extracellular respiration, highlights recent discoveries, and discusses critically the influence of different strategies for terminal electron transfer reactions.
Suspicion of Mycobacterium avium subsp. paratuberculosis Transmission between Cattle and Wild-Living Red Deer (Cervus elaphus) by Multitarget Genotyping
Authors: Fritsch Isabel , Luyven Gabriele , Köhler Heike , Lutz Walburga , Möbius Petra
Published: December 2011

Multitarget genotyping of the etiologic agent
Mycobacterium avium
subsp.
paratuberculosis
is necessary for epidemiological tracing of paratuberculosis (Johne's disease). The study was undertaken to assess the informative value of different typing techniques and individual genome markers by investigation of
M. avium
subsp.
paratuberculosis
transmission between wild-living red deer and farmed cattle with known shared habitats. Fifty-three
M. avium
subsp.
paratuberculosis
type II isolates were differentiated by short sequence repeat analysis (SSR; 4 loci), mycobacterial interspersed repetitive-unit–variable-number tandem-repeat analysis (MIRU-VNTR; 8 loci), and restriction fragment length polymorphism analysis based on IS
900
(IS
900
-RFLP) using BstEII and PstI digestion. Isolates originated from free-living red deer (
Cervus elaphus
) from Eifel National Park (
n
= 13), six cattle herds living in the area of this park (
n
= 23), and five cattle herds without any contact with these red deer (
n
= 17). Data based on individual herds and genotypes verified that SSR G2 repeats did not exhibit sufficient stability for epidemiological studies. Two common SSR profiles (without G2 repeats), nine MIRU-VNTR patterns, and nine IS
900
-RFLP patterns were detected, resulting in 17 genotypes when combined. A high genetic variability was found for red deer and cattle isolates within and outside Eifel National Park, but it was revealed only by combination of different typing techniques. Results imply that within this restricted area, wild-living and farmed animals maintain a reservoir for specific
M. avium
subsp.
paratuberculosis
genotypes. No host relation of genotypes was obtained. Results suggested that four genotypes had been transmitted between and within species and that one genotype had been transmitted between cattle herds only. Use of multitarget genotyping for
M. avium
subsp.
paratuberculosis
type II strains and sufficiently stable genetic markers is essential for reliable interpretations of epidemiological studies on paratuberculosis.
Mutation of the NADH Oxidase Gene (
nox
) Reveals an Overlap of the Oxygen- and Acid-Mediated Stress Responses in Streptococcus mutans
Authors: Derr Adam M. , Faustoferri Roberta C. , Betzenhauser Matthew J. , Gonzalez Kaisha , Marquis Robert E. , Quivey Robert G.
Published: December 2011

NADH oxidase (Nox) is a flavin-containing enzyme used by
Streptococcus mutans
to reduce dissolved oxygen encountered during growth in the oral cavity. In this study, we characterized the role of the NADH oxidase in the oxidative and acid stress responses of
S. mutans
. A
nox
-defective mutant strain of
S. mutans
and its parental strain, the genomic type strain UA159, were exposed to various oxygen concentrations at pH values of 5 and 7 to better understand the adaptive mechanisms used by the organism to withstand environmental pressures. With the loss of
nox
, the activities of oxygen stress response enzymes such as superoxide dismutase and glutathione oxidoreductase were elevated compared to those in controls, resulting in a greater adaptation to oxygen stress. In contrast, the loss of
nox
led to a decreased ability to grow in a low-pH environment despite an increased resistance to severe acid challenge. Analysis of the membrane fatty acid composition revealed that for both the
nox
mutant and UA159 parent strain, growth in an oxygen-rich environment resulted in high proportions of unsaturated membrane fatty acids, independent of external pH. The data indicate that
S. mutans
membrane fatty acid composition is responsive to oxidative stress, as well as changes in environmental pH, as previously reported (E. M. Fozo and R. G. Quivey, Jr., Appl. Environ. Microbiol.
70
:929–936, 2004). The heightened ability of the
nox
strain to survive acidic and oxidative environmental stress suggests a multifaceted response system that is partially dependent on oxygen metabolites.
Quantifying the Reduction in Potential Health Risks by Determining the Sensitivity of Poliovirus Type 1 Chat Strain and Rotavirus SA-11 to Electron Beam Irradiation of Iceberg Lettuce and Spinach
Authors: Espinosa Ana Cecilia , Jesudhasan Palmy , Arredondo René , Cepeda Martha , Mazari-Hiriart Marisa , Mena Kristi D. , Pillai Suresh D.
Published: December 2011

Fresh produce, such as lettuce and spinach, serves as a route of food-borne illnesses. The U.S. FDA has approved the use of ionizing irradiation up to 4 kGy as a pathogen kill step for fresh-cut lettuce and spinach. The focus of this study was to determine the inactivation of poliovirus and rotavirus on lettuce and spinach when exposed to various doses of high-energy electron beam (E-beam) irradiation and to calculate the theoretical reduction in infection risks that can be achieved under different contamination scenarios and E-beam dose applications. The D
10
value (dose required to reduce virus titers by 90%) (standard error) of rotavirus on spinach and lettuce was 1.29 (± 0.64) kGy and 1.03 (± 0.05) kGy, respectively. The D
10
value (standard error) of poliovirus on spinach and lettuce was 2.35 (± 0.20) kGy and 2.32 (± 0.08) kGy, respectively. Risk assessment of data showed that if a serving (∼14 g) of lettuce was contaminated with 10 PFU/g of poliovirus, E-beam irradiation at 3 kGy will reduce the risk of infection from >2 in 10 persons to approximately 6 in 100 persons. Similarly, if a serving size (∼0.8 g) of spinach is contaminated with 10 PFU/g of rotavirus, E-beam irradiation at 3 kGy will reduce infection risks from >3 in 10 persons to approximately 5 in 100 persons. The results highlight the value of employing E-beam irradiation to reduce public health risks but also the critical importance of adhering to good agricultural practices that limit enteric virus contamination at the farm and in packing houses.
Differential Targeting of the E-Cadherin/β-Catenin Complex by Gram-Positive Probiotic Lactobacilli Improves Epithelial Barrier Function
Authors: Hummel Stephanie , Veltman Katharina , Cichon Christoph , Sonnenborn Ulrich , Schmidt M. Alexander
Published: December 2011

The intestinal ecosystem is balanced by dynamic interactions between resident and incoming microbes, the gastrointestinal barrier, and the mucosal immune system. However, in the context of inflammatory bowel diseases (IBD), where the integrity of the gastrointestinal barrier is compromised, resident microbes contribute to the development and perpetuation of inflammation and disease. Probiotic bacteria have been shown to exert beneficial effects, e.g., enhancing epithelial barrier integrity. However, the mechanisms underlying these beneficial effects are only poorly understood. Here, we comparatively investigated the effects of four probiotic lactobacilli, namely,
Lactobacillus acidophilus
,
L. fermentum
,
L. gasseri
, and
L. rhamnosus
, in a T84 cell epithelial barrier model. Results of DNA microarray experiments indicating that lactobacilli modulate the regulation of genes encoding in particular adherence junction proteins such as E-cadherin and β-catenin were confirmed by quantitative reverse transcription-PCR (qRT-PCR). Furthermore, we show that epithelial barrier function is modulated by Gram-positive probiotic lactobacilli via their effect on adherence junction protein expression and complex formation. In addition, incubation with lactobacilli differentially influences the phosphorylation of adherence junction proteins and the abundance of protein kinase C (PKC) isoforms such as PKCδ that thereby positively modulates epithelial barrier function. Further insight into the underlying molecular mechanisms triggered by these probiotics might also foster the development of novel strategies for the treatment of gastrointestinal diseases (e.g., IBD).
Role of (p)ppGpp in Biofilm Formation by Enterococcus faecalis
Authors: Chávez de Paz Luis E. , Lemos José A. , Wickström Claes , Sedgley Christine M.
Published: December 2011

Enterococcus faecalis
strain OG1RF and its (p)ppGpp-deficient Δ
relA
, Δ
relQ
, and Δ
relA
Δ
relQ
mutants were grown in biofilms and evaluated for growth profiles, biofilm morphology, cell viability, and proteolytic activity.
E. faecalis
lacking (p)ppGpp had a diminished capacity to sustain biofilm formation over an extended period of time and expressed abundant proteolytic activity.
Correlation between Quantitative PCR and Culture-Based Methods for Measuring Enterococcus spp. over Various Temporal Scales at Three California Marine Beaches
Authors: Converse Reagan R. , Griffith John F. , Noble Rachel T. , Haugland Richard A. , Schiff Kenneth C. , Weisberg Stephen B.
Published: December 2011

Several studies have examined how fecal indicator bacteria (FIB) measurements compare between quantitative PCR (qPCR) and the culture methods it is intended to replace. Here, we extend those studies by examining the stability of that relationship within a beach, as affected by time of day and seasonal variations in source.
Enterococcus
spp. were quantified at three southern California beaches in the morning and afternoon using two qPCR assays, membrane filtration, and defined-substrate testing. While qPCR and culture-based measurements were consistently and significantly correlated, strength of the correlation varied both among and within beaches. Correlations were higher in the morning (0.45 < ρ < 0.74 [
P
< 0.002]) than in the afternoon (0.18 < ρ < 0.45 [
P
< 0.021]) and higher when the fecal contamination was concentrated (0.38 < ρ < 0.83 [
P
< 0.001]) than when it was diffuse (0.19 < ρ < 0.34 [
P
< 0.003]). The ratios of culture-based and qPCR results (CFU or most probable number [MPN] per calibrator cell equivalents [CCE]) also varied spatially and temporally. Ratios ranged between 0.04 and 0.85 CFU or MPN per CCE and were lowest at the beach affected by diffuse pollution. Patterns in the ratios over the course of the day were dissimilar across beaches, increasing with time at one beach and decreasing at another. The spatial and temporal variability we observed indicate that the empirical relationship between culture-based and qPCR results is not universal, even within a beach.
Dichloromethane Fermentation by a Dehalobacter sp. in an Enrichment Culture Derived from Pristine River Sediment
Authors: Justicia-Leon Shandra D. , Ritalahti Kirsti M. , Mack E. Erin , Löffler Frank E.
Published: December 2011

Dichloromethane (DCM) as the sole substrate supported growth of a
Dehalobacter
sp. in an enrichment culture derived from noncontaminated river sediment. DCM was not reductively dechlorinated, and acetate was produced, indicating DCM fermentation and further suggesting
Dehalobacter
growth is not limited to organohalide respiration.