bluuebunny/crossref_metadata_2025_split huggingface dataset:
Role of Multiple HLR1 Sequences in the Regulation of the Dual Promoters of thepsaABGenes inSynechocystissp. PCC 6803
Authors: Takahashi Tomoko , Nakai Nanako , Muramatsu Masayuki , Hihara Yukako 
Published: May 2010

ABSTRACTPreviously, we analyzed the promoter architecture of thepsaABgenes encoding reaction center subunits of photosystem I (PSI) in the cyanobacteriumSynechocystissp. PCC 6803. There exist two promoters, P1 and P2, both of which show typical high-light (HL) response of PSI genes; their activities are high under low-light (LL) conditions but rapidly downregulated upon the shift to HL conditions. In this study, it was suggested that a response regulator RpaB binds to multiple high-light regulatory 1 (HLR1) sequences in the upstream region of thepsaABgenes. We explored the regulatory role ofcis-elements, including these HLR1 sequences on the individual activity of P1 and P2. Under LL conditions, the most influentialcis-element is HLR1C (−62 to −45, relative to the transcriptional starting point of P1) working for positive regulation of P1. The other HLR1 sequences also affect the promoter activity under LL conditions; HLR1A (−255 to −238) is involved in repression of P1, whereas HLR1B (−153 to −126) works for activation of P2. Upon the shift to HL conditions, regulation via HNE2 located within the region from −271 to −177 becomes active in order to downregulate both P1 and P2 activities. A positive effect of HLR1B on P2 may persist under HL. These results suggest thatcis-elements, including multiple HLR1 sequences, differently regulate the activities of dual promoters of thepsaABgenes to achieve the fine-tuning of the gene expression.
Evidence for Widespread Gene Control Function by the
ydaO
Riboswitch Candidate
Authors: Block Kirsten F. , Hammond Ming C. , Breaker Ronald R. 
Published: May 2010

ABSTRACT

Nearly all representatives of experimentally validated riboswitch classes in bacteria control the expression of genes for the transport or synthesis of key metabolic compounds. Recent findings have revealed that some riboswitches also regulate genes involved in physiological changes, virulence, and stress responses. Many novel RNA motifs are being identified by using bioinformatics algorithms that search for conserved sequence and structural features located in intergenic regions. Some of these RNAs are likely to function as riboswitches for metabolites or signaling compounds, and confirmation of this function would reveal the basis of the genetic control of new regulons. Herein we describe the analysis of the
ydaO
riboswitch candidate, which represents one of the most widespread candidates remaining to be validated. These RNAs are common in Gram-positive bacteria, and their genomic associations with diverse genes suggest that they sense a compound that signals broader physiological changes. We determined that the
ydaO
motif exhibits sequence- and structure-dependent gene control, and reporter assays indicate that its natural ligand is present even when cells are grown in defined media. A transposon-mediated knockout screen resulted in mutants with a dysregulated expression of genes controlled by the RNA motif. The mutations disrupt genes that drastically modulate energy-generating pathways, suggesting that the intracellular concentration of the ligand sensed by the
ydaO
motif is altered under these stress conditions.
The Threshold Level of the Sensor Histidine Kinase KinA Governs Entry into Sporulation in
Bacillus subtilis
Authors: Eswaramoorthy Prahathees , Duan Daniel , Dinh Jeffrey , Dravis Ashlee , Devi Seram Nganbiton , Fujita Masaya 
Published: May 2010

ABSTRACT

Sporulation in
Bacillus subtilis
is controlled by a complex gene regulatory circuit that is activated upon nutrient deprivation. The initial process is directed by the phosphorelay, involving the major sporulation histidine kinase (KinA) and two additional phosphotransferases (Spo0F and Spo0B), that activates the master transcription factor Spo0A. Little is known about the initial event and mechanisms that trigger sporulation. Using a strain in which the synthesis of KinA is under the control of an IPTG (isopropyl-β-
d
-thiogalactopyranoside)-inducible promoter, here we demonstrate that inducing the synthesis of the KinA beyond a certain level leads to the entry of the irreversible process of sporulation irrespective of nutrient availability. Moreover, the engineered cells expressing KinA under a σ
H
-dependent promoter that is similar to but stronger than the endogenous
kinA
promoter induce sporulation during growth. These cells, which we designated COS (
co
nstitutive
s
porulation) cells, exhibit the morphology and properties of sporulating cells and express sporulation marker genes under nutrient-rich conditions. Thus, we created an engineered strain displaying two cell cycles (growth and sporulation) integrated into one cycle irrespective of culture conditions, while in the wild type, the appropriate cell fate decision is made depending on nutrient availability. These results suggest that the threshold level of the major sporulation kinase acts as a molecular switch to determine cell fate and may rule out the possibility that the activity of KinA is regulated in response to the unknown signal(s).
Mutations Affecting Export and Activity of Cytolysin A from
Escherichia coli
Authors: Ludwig Albrecht , Völkerink Guido , von Rhein Christine , Bauer Susanne , Maier Elke , Bergmann Birgit , Goebel Werner , Benz Roland 
Published: May 2010

ABSTRACT

Cytolysin A (known as ClyA, HlyE, and SheA) is a cytolytic pore-forming protein toxin found in several
Escherichia coli
and
Salmonella enterica
strains. The structure of its water-soluble monomeric form and that of dodecameric ClyA pores is known, but the mechanisms of ClyA export from bacterial cells and of pore assembly are only partially understood. Here we used site-directed mutagenesis to study the importance of different regions of the
E. coli
ClyA protein for export and activity. The data indicate that ClyA translocation to the periplasm requires several protein segments located closely adjacent to each other in the “tail” domain of the ClyA monomer, namely, the N- and C-terminal regions and the hydrophobic sequence ranging from residues 89 to 101. Deletion of most of the “head” domain of the monomer (residues 181 to 203), on the other hand, did not strongly affect ClyA secretion, suggesting that the tail domain plays a particular role in export. Furthermore, we found that the N-terminal amphipathic helix αA1 of ClyA is crucial for the formation and the properties of the transmembrane channel, and hence for hemolytic activity. Several mutations affecting the C-terminal helix αG, the “β-tongue” region in the head domain, or the hydrophobic region in the tail domain of the ClyA monomer strongly impaired the hemolytic activity and reduced the activity toward planar lipid bilayer membranes but did not totally prevent formation of wild-type-like channels in these artificial membranes. The latter regions thus apparently promote membrane interaction without being directly required for pore formation in a lipid bilayer.
Characterization of Energy-Conserving Hydrogenase B in
Methanococcus maripaludis
Authors: Major Tiffany A. , Liu Yuchen , Whitman William B. 
Published: May 2010

ABSTRACT

The
Methanococcus maripaludis
energy-conserving hydrogenase B (Ehb) generates low potential electrons required for autotrophic CO
2
assimilation. To analyze the importance of individual subunits in Ehb structure and function, markerless in-frame deletions were constructed in a number of
M. maripaludis ehb
genes. These genes encode the large and small hydrogenase subunits (
ehbN
and
ehbM
, respectively), a polyferredoxin and ferredoxin (
ehbK
and
ehbL
, respectively), and an ion translocator (
ehbF
). In addition, a gene replacement mutation was constructed for a gene encoding a putative membrane-spanning subunit (
ehbO
). When grown in minimal medium plus acetate (McA), all
ehb
mutants had severe growth deficiencies except the Δ
ehbO
::
pac
strain. The membrane-spanning ion translocator (Δ
ehbF
) and the large hydrogenase subunit (Δ
ehbN
) deletion strains displayed the severest growth defects. Deletion of the
ehbN
gene was of particular interest because this gene was not contiguous to the
ehb
operon. In-gel activity assays and Western blots confirmed that EhbN was part of the membrane-bound Ehb hydrogenase complex. The Δ
ehbN
strain was also sensitive to growth inhibition by aryl acids, indicating that Ehb was coupled to the indolepyruvate oxidoreductase (Ior), further supporting the hypothesis that Ehb provides low potential reductants for the anabolic oxidoreductases in
M. maripaludis
.
Fragmented QRS and Mortality Risk in Patients With Left Ventricular Dysfunction
Authors: Cheema Aamir , Khalid Adnan , Wimmer Alan , Bartone Cheryl , Chow Theodore , Spertus John A. , Chan Paul S. 
Published: May 2010

Background—
Fragmented QRS (fQRS) has been shown to predict cardiac events in select patient populations. Whether fQRS improves patient selection for primary prevention patients eligible for implantable cardioverter-defibrillator (ICD) therapy remains unknown.

Methods and Results—

In a prospective, multisite cohort of 842 patients with left ventricular dysfunction (ejection fraction ≤35%) representing both ischemic and nonischemic etiology, the presence of fQRS on ECG was assessed using standardized criteria. The association between fQRS and all-cause and arrhythmic mortality was evaluated overall and stratified by ICD status using multivariable Cox regression models, adjusted for demographic, clinical, and treatment variables. Fragmented QRS was present in 274 (32.5%) patients, and there were 191 (22.7%) deaths during a mean follow-up of 40±17 months. Rates of all-cause mortality did not differ between the fQRS+ (19.7%) and fQRS− (24.1%) groups; adjusted hazard ratio, 0.88; 95% confidence interval, 0.63–1.22;
P
=0.43. Additionally, rates of arrhythmic mortality were similar between the fQRS+ (9.9%) and fQRS− (12.7%) groups: adjusted hazard ratio, 0.77; 95% confidence interval, 0.49–1.31;
P
=0.38. Subgroup analyses found no association between fQRS and mortality when the cohort was further stratified by ICD status, etiology of left ventricular dysfunction, wide (≥120 ms) versus narrow (<120 ms) QRS duration, or fQRS myocardial territory.

Conclusions—
In this prospective, multisite cohort of primary prevention patients with left ventricular dysfunction, the presence of fQRS on ECG was not associated with a higher risk of either all-cause or arrhythmic mortality. These findings do not provide evidence that fQRS would be effective in risk stratifying primary prevention patients eligible for ICD therapy.
Atrial Fibrillation Cycle Length Is a Sole Independent Predictor of a Substrate for Consecutive Arrhythmias in Patients With Persistent Atrial Fibrillation
Authors: Drewitz Imke , Willems Stephan , Salukhe Tushar V. , Steven Daniel , Hoffmann Boris A. , Servatius Helge , Bock Karsten , Aydin Muhammet Ali , Wegscheider Karl , Meinertz Thomas , Rostock Thomas 
Published: May 2010

Background—
Termination of persistent atrial fibrillation (AF) can be achieved through ablation, with the majority of patients terminating to an atrial tachycardia (AT) and fewer directly to sinus rhythm (SR). We aimed to identify potential predictors for the existence of a substrate for AT on termination to SR.

Methods and Results—

We assessed 95 persistent AF patients (age, 60±10 years) who underwent catheter ablation to the end point of AF termination. Forty patients terminated directly to SR (SRterm) and 55 to ATs (ATterm). Compared with the ATterm group, the SRterm group were younger (56±10 versus 63±9 years,
P
=0.001), had shorter durations of AF before ablation (9±26 versus 14±20 months,
P
<0.001), smaller left atrial diameters (41±5 versus 45±5 mm,
P
=0.015), and longer baseline AF cycle lengths (178±23 versus 159±31 ms,
P
=0.005). However, AF cycle length was the sole independent predictor of direct termination to SR. The most frequent AF termination site in SRterm patients was the pulmonary veins (53%), whereas in ATterm patients this was within the left atrium (58%). After follow-up of 12±6 months, there was a trend toward a greater proportion of patients in SR among those who terminated directly to SR after a single procedure. The most frequent type of recurrence was paroxysmal AF in SRterm patients and AT in ATterm patients.

Conclusions—
Patients who terminate to SR through ablation without an intermediate AT are characterized by a less altered arrhythmogenic substrate. Baseline AF cycle lengths emerged as a sole independent predictor of a substrate for consecutive arrhythmias.
J Wave, QRS Slurring, and ST Elevation in Athletes With Cardiac Arrest in the Absence of Heart Disease
Authors: Cappato Riccardo , Furlanello Francesco , Giovinazzo Valerio , Infusino Tommaso , Lupo Pierpaolo , Pittalis Mario , Foresti Sara , De Ambroggi Guido , Ali Hussam , Bianco Elisabetta , Riccamboni Roberto , Butera Gianfranco , Ricci Cristian , Ranucci Marco , Pelliccia Antonio , De Ambroggi Luigi 
Published: May 2010

Background—
QRS-ST changes in the inferior and lateral ECG leads are frequently observed in athletes. Recent studies have suggested a potential arrhythmogenic significance of these findings in the general population. The aim of our study was to investigate whether QRS-ST changes are markers of cardiac arrest (CA) of unexplained cause or sudden death in athletes.

Methods and Results—

In 21 athletes (mean age, 27 years; 5 women) with cardiac arrest or sudden death, the ECG recorded before or immediately after the clinical event was compared with the ECG of 365 healthy athletes eligible for competitive sport activity. We measured the height of the J wave and ST elevation and searched for the presence of QRS slurring in the terminal portion of QRS. QRS slurring in any lead was present in 28.6% of cases and in 7.6% of control athletes (
P
=0.006). A J wave and/or QRS slurring without ST elevation in the inferior (II, III, and aVF) and lateral leads (V
4
to V
6
) were more frequently recorded in cases than in control athletes (28.6% versus 7.9%,
P
=0.007). Among those with cardiac arrest, arrhythmia recurrences did not differ between the subgroups with and without J wave or QRS slurring during a median 36-month follow-up of sport discontinuation.

Conclusions—
J wave and/or QRS slurring was found more frequently among athletes with cardiac arrest/sudden death than in control athletes. Nevertheless, the presence of this ECG pattern appears not to confer a higher risk for recurrent malignant ventricular arrhythmias.
Community engagement for health promotion
Authors: Tse Samson , Laverack Glenn , Nayar Shoba , Foroughian Shirin 
Published: May 2010

Objectives and Settings: A growing Asian population currently resides in New Zealand, yet under half of this population claim the support they are entitled to in the face of an accident and injury. This research is focused on identifying ways of effectively engaging the Chinese community in health-promotion programmes to prevent and/or reduce injuries. Methods: Research field work was conducted based on a qualitative approach. Interviews were carried out with 32 members of the Chinese community and six experts from six different organizations working with the Chinese community in Auckland, New Zealand. Results: Interviews revealed that issues of resettlement and relocation, lack of communication, community readiness and community capacity all impacted on the delivery of health-promotion activities within the Chinese community. Conclusion: The findings led to a series of seven steps as guidelines to engage the Chinese community to prevent and/or reduce injuries towards improving the quality of their lives. The underlying principles of the guidelines helped in the development of a community engagement approach for Chinese communities in Auckland, New Zealand.
Examining differences between light and heavier smoking vocational students
Authors: de Araújo Vanessa A , Loukas Alexandra , Gottlieb Nell H 
Published: May 2010

Objective: To examine differences between light and heavier smoking vocational/technical students in tobacco use, related behaviors, and cessation. Design: Cross-sectional. Setting and Methods: Two hundred and four smokers attending two vocational/technical colleges in east Texas, USA, completed an anonymous survey during a regularly scheduled class in Fall, 2004 or Spring, 2005. Results: Heavier smokers (39.7 per cent of the sample) were more likely than light smokers to be European American, to be dependent on cigarettes, to use cigarettes in a variety of situations, to use medication to quit smoking, and to be less likely to report a desire to quit on their own. The two groups did not differ on gender or the use of cigars and chewing tobacco. Conclusion: Given the disproportionately high rates of tobacco use among vocational/technical students, results from this study indicate that salient anti-tobacco programs that can be implemented at the vocational school and that target light and heavier smoking students are needed.
The critical roles of platelet activation and reduced NO bioavailability in fatal pulmonary arterial hypertension in a murine hemolysis model
Authors: Hu Weiguo , Jin Richard , Zhang Jinyan , You Tao , Peng Zhihai , Ge Xiaowen , Bronson Roderick T. , Halperin Jose A. , Loscalzo Joseph , Qin Xuebin 
Published: May 2010

AbstractPulmonary arterial hypertension (PAH) is suspected to be a strong mortality determinant of hemolytic disorders. However, direct contribution of acute intravascular hemolysis to fatal PAH has not been investigated. The roles of nitric oxide (NO) insufficiency and platelet activation in hemolysis-associated fatal PAH have been suspected but not been experimentally studied. We recently generated a unique intravascular hemolysis mouse model in which the membrane toxin, intermedilysin (ILY), exclusively lyses the erythrocytes of transgenically expressing human CD59 mice (ThCD59RBC), thereby inducing ILY-dose–dependent massive hemolysis. Using this murine hemolysis model, we found that the acute increase in pulmonary arterial pressure leading to right ventricle failure caused sudden death. Reduced NO bioavailability and massive platelet activation/aggregation leading to the formation of massive thrombosis specifically in the pulmonary microvasculature played the critical roles in pathogenesis of acute hemolysis-associated fatal PAH. Therapeutic interventions enhancing NO bioactivity or inhibiting platelet activation prevented sudden death or prolonged survival time via the suppression of the acute increase in pulmonary arterial pressure and improvement of right ventricle function. These findings further highlight the importance of the inhibition of platelet activation and the enhancement of NO bioavailability for the treatment and prevention of hemolysis-associated (fatal) PAH.
Adenovirus capsid-display of the retro-oriented human complement inhibitor DAF reduces Ad vector–triggered immune responses in vitro and in vivo
Authors: Seregin Sergey S. , Aldhamen Yasser A. , Appledorn Daniel M. , Hartman Zachary C. , Schuldt Nathaniel J. , Scott Jeannine , Godbehere Sarah , Jiang Haixiang , Frank Michael M. , Amalfitano Andrea 
Published: May 2010

Abstract
Adenovirus (Ad) vectors are widely used in human clinical trials. However, at higher dosages, Ad vector–triggered innate toxicities remain a major obstacle to many applications. Ad interactions with the complement system significantly contribute to innate immune responses in several models of Ad-mediated gene transfer. We constructed a novel class of Ad vectors, genetically engineered to “capsid-display” native and retro-oriented versions of the human complement inhibitor decay-accelerating factor (DAF), as a fusion protein from the C-terminus of the Ad capsid protein IX. In contrast to conventional Ad vectors, DAF-displaying Ads dramatically minimized complement activation in vitro and complement-dependent immune responses in vivo. DAF-displaying Ads did not trigger thrombocytopenia, minimized endothelial cell activation, and had diminished inductions of proinflammatory cytokine and chemokine responses. The retro-oriented display of DAF facilitated the greatest improvements in vivo, with diminished activation of innate immune cells, such as dendritic and natural killer cells. In conclusion, Ad vectors can capsid-display proteins in a manner that not only retains the functionality of the displayed proteins but also potentially can be harnessed to improve the efficacy of this important gene transfer platform for numerous gene transfer applications.
Regulation of the cardiomyocyte transcriptome vs translatome by endothelin-1 and insulin: translational regulation of 5' terminal oligopyrimidine tract (TOP) mRNAs by insulin
Authors: Markou Thomais , Marshall Andrew K , Cullingford Timothy E , Tham El L , Sugden Peter H , Clerk Angela 
Published: May 2010

Abstract

Background
Changes in cellular phenotype result from underlying changes in mRNA transcription and translation. Endothelin-1 stimulates cardiomyocyte hypertrophy with associated changes in mRNA/protein expression and an increase in the rate of protein synthesis. Insulin also increases the rate of translation but does not promote overt cardiomyocyte hypertrophy. One mechanism of translational regulation is through 5' terminal oligopyrimidine tracts (TOPs) that, in response to growth stimuli, promote mRNA recruitment to polysomes for increased translation. TOP mRNAs include those encoding ribosomal proteins, but the full panoply remains to be established. Here, we used microarrays to compare the effects of endothelin-1 and insulin on the global transcriptome of neonatal rat cardiomyocytes, and on mRNA recruitment to polysomes (i.e. the translatome).

Results
Globally, endothelin-1 and insulin (1 h) promoted >1.5-fold significant (false discovery rate < 0.05) changes in expression of 341 and 38 RNAs, respectively. For these transcripts with this level of change there was little evidence of translational regulation. However, 1336 and 712 RNAs had >1.25-fold significant changes in expression in total and/or polysomal RNA induced by endothelin-1 or insulin, respectively, of which ~35% of endothelin-1-responsive and ~56% of insulin-responsive transcripts were translationally regulated. Of mRNAs for established proteins recruited to polysomes in response to insulin, 49 were known TOP mRNAs with a further 15 probable/possible TOP mRNAs, but 49 had no identifiable TOP sequences or other consistent features in the 5' untranslated region.

Conclusions
Endothelin-1, rather than insulin, substantially affects global transcript expression to promote cardiomyocyte hypertrophy. Effects on RNA recruitment to polysomes are subtle, with differential effects of endothelin-1 and insulin on specific transcripts. Furthermore, although insulin promotes recruitment of TOP mRNAs to cardiomyocyte polysomes, not all recruited mRNAs are TOP mRNAs.