bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dissociation between blood pressure and heart rate response to hypoxia after bilateral carotid body removal in men with systolic heart failure
Authors: Niewinski Piotr , Janczak Dariusz , Rucinski Artur , Tubek Stanislaw , Engelman Zoar J. , Jazwiec Przemyslaw , Banasiak Waldemar , Sobotka Paul A. , Hart Emma C. J. , Paton Julian F. R. , Ponikowski Piotr 
Published: November 2013

New Findings
What is the central question of this study?
Carotid body denervation removes the ventilatory response to acute hypoxia, although haemodynamic responses to acute hypoxia after carotid body removal have not been described conclusively in humans.
What is the main finding and its importance?
Carotid body removal results in dissociation of heart rate and blood pressure responses to hypoxia in human subjects. While the heart rate response (tachycardia) is maintained, there is a significant attenuation of the blood pressure response (hypertension), which indicates the existence of different sensory afferent pathways in the haemodynamic response to hypoxia that has important clinical implications for this novel therapeutic modality.
While the ventilatory response to hypoxia is known to be mediated by the carotid bodies, the origin of the haemodynamic alterations evoked by hypoxia is less certain. Bilateral carotid body removal (CBR) performed to treat congestive heart failure may serve as a model to improve our understanding of haemodynamic responses to hypoxia in humans. We studied six congestive heart failure patients before and 1 month after CBR [median (interquartile range): age, 58.5 (56–61) years old; and ejection fraction, 32 (25–34)%]. Peripheral chemosensitivity (hypoxic ventilatory response) was equated to the slope relating lowest oxygen saturation to highest minute ventilation following exposures to hypoxia. Likewise, systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) slopes were calculated as slopes relating the lowest oxygen saturations to the highest SBP, DBP and HR responses. We found that CBR reduces the hypoxic ventilatory response (∆91%, P < 0.05), SBP (∆71%, P < 0.05) and DBP slopes (∆59%, P = 0.07). In contrast, the HR slope remained unchanged. The dissociation between the blood pressure and HR responses after CBR shows involvement of a different chemoreceptive site(s) maintaining the response to acute hypoxia. We conclude that carotid bodies are responsible for ventilatory and blood pressure responses, while the HR response might be mediated by the aortic bodies. The significant reduction of the blood pressure response to hypoxia after CBR suggests a decrease in sympathetic tone, which is of particular clinical relevance in congestive heart failure.
Differential visceral pain sensitivity and colonic morphology in four common laboratory rat strains
Authors: O'Malley Dervla , Julio‐Pieper Marcela , O'Mahony Siobhain M. , Dinan Timothy G. , Cryan John F. 
Published: November 2013

New Findings
What is the central question of this study?
Does stress sensitivity and susceptibility to inflammation innate to certain rat strains make them vulnerable to bowel dysfunction?
What is the main finding and its importance?
Of four different rat strains, the Lewis rat, which displays both susceptibility to gastrointestinal inflammation and sensitivity to stress, exhibits the most aberrant gastrointestinal morphology and visceral pain sensitivity. Given the similarities to human functional bowel disorders, such as irritable bowel syndrome, this may make it a good model of this disease.
Irritable bowel syndrome is a common, debilitating gastrointestinal (GI) disorder characterized by episodic exacerbations of symptoms such as abdominal pain, bloating and altered bowel habit. Contributory factors for the development of irritable bowel syndrome include genetics, childhood trauma and prior GI infection leading to chronic low‐grade inflammation or immune activation. Additional considerations in comprehending the chronic relapsing pattern that typifies irritable bowel syndrome symptoms are the effects of both psychosocial and infection‐related stresses. Background stress and immune profiles can influence gut permeability and visceral pain sensitivity. This study examined whether innate susceptibility to inflammation and stress sensitivity in four rat strains is associated with bowel dysfunction. The pain threshold to colorectal distension was assessed in Lewis, Fischer (F344) and spontaneously hypertensive rats and compared with Sprague–Dawley control animals. Colons were subsequently excised and morphologically assessed for total length, goblet cell hyperplasia and muscle and mucosal thickness. Lewis rats displayed visceral hypersensitivity compared with other strains. At a morphological level, the gastrointestinal tract from these rats displayed mucosal goblet cell hyperplasia and alterations in muscle layer thickness. The Lewis rat strain, which is reported to have increased susceptibility to GI inflammation in addition to stress sensitivity, had the most prominent features of physiological and morphological GI dysfunction. These data support the hypothesis that background strain is a key factor in the development and exacerbation of bowel dysfunction in rodent models.
Competition for Ammonia Influences the Structure of Chemotrophic Communities in Geothermal Springs
Authors: Hamilton Trinity L. , Koonce Evangeline , Howells Alta , Havig Jeff R. , Jewell Talia , de la Torre José R. , Peters John W. , Boyd Eric S. 
Published: November 2013

ABSTRACT

Source waters sampled from Perpetual Spouter hot spring (pH 7.03, 86.4°C), Yellowstone National Park, WY, have low concentrations of total ammonia, nitrite, and nitrate, suggesting nitrogen (N) limitation and/or tight coupling of N cycling processes. Dominant small-subunit rRNA sequences in Perpetual Spouter source sediments are closely affiliated with the ammonia-oxidizing archaeon “
Candidatus
Nitrosocaldus yellowstonii” and the putatively nitrogen-fixing (diazotrophic) bacterium
Thermocrinis albus
, respectively, suggesting that these populations may interact at the level of the bioavailable N pool, specifically, ammonia. This hypothesis was evaluated by using a combination of geochemical, physiological, and transcriptomic analyses of sediment microcosms. Amendment of microcosms with allylthiourea, an inhibitor of ammonia oxidation, decreased rates of acetylene reduction (a proxy for N
2
fixation) and nitrite production (a proxy for ammonia oxidation) and decreased transcript levels of structural genes involved in both nitrogen fixation (
nifH
) and ammonia oxidation (
amoA
). In contrast, amendment of microcosms with ammonia stimulated nitrite production and increased
amoA
transcript levels while it suppressed rates of acetylene reduction and decreased
nifH
transcript levels. Sequencing of amplified
nifH
and
amoA
transcripts from native sediments, as well as microcosms, at 2 and 4 h postamendment, indicates that the dominant and responsive populations involved in ammonia oxidation and N
2
fixation are closely affiliated with
Ca
. Nitrosocaldus yellowstonii and
T. albus
, respectively. Collectively, these results suggest that ammonia-oxidizing archaea, such as
Ca
. Nitrosocaldus yellowstonii, have an apparent affinity for ammonia that is higher than that of the diazotrophs present in this ecosystem. Depletion of the bioavailable N pool through the activity of ammonia-oxidizing archaea likely represents a strong selective pressure for the inclusion of organisms capable of nitrogen fixation in geothermal communities. These observations help to explain the strong pattern in the codistribution of ammonia-oxidizing archaea and diazotrophs in circumneutral-to-alkaline geothermal springs.
Interspecies Interactions Determine the Impact of the Gut Microbiota on Nutrient Allocation in Drosophila melanogaster
Authors: Newell Peter D. , Douglas Angela E. 
Published: November 2013

ABSTRACT

The animal gut is perpetually exposed to microorganisms, and this microbiota affects development, nutrient allocation, and immune homeostasis. A major challenge is to understand the contribution of individual microbial species and interactions among species in shaping these microbe-dependent traits. Using the
Drosophila melanogaster
gut microbiota, we tested whether microbe-dependent performance and nutritional traits of
Drosophila
are functionally modular, i.e., whether the impact of each microbial taxon on host traits is independent of the presence of other microbial taxa. Gnotobiotic flies were constructed with one or a set of five of the
Acetobacter
and
Lactobacillus
species which dominate the gut microbiota of conventional flies (
Drosophila
with untreated microbiota). Axenic (microbiota-free) flies exhibited prolonged development time and elevated glucose and triglyceride contents. The low glucose content of conventional flies was recapitulated in gnotobiotic
Drosophila
flies colonized with any of the 5 bacterial taxa tested. In contrast, the development rates and triglyceride levels in monocolonized flies varied depending on the taxon present:
Acetobacter
species supported the largest reductions, while most
Lactobacillus
species had no effect. Only flies with both
Acetobacter
and
Lactobacillus
had triglyceride contents restored to the level in conventional flies. This could be attributed to two processes:
Lactobacillus
-mediated promotion of
Acetobacter
abundance in the fly and a significant negative correlation between fly triglyceride content and
Acetobacter
abundance. We conclude that the microbial basis of host traits varies in both specificity and modularity; microbe-mediated reduction in glucose is relatively nonspecific and modular, while triglyceride content is influenced by interactions among microbes.
pH-Dependent Activation of Streptomyces hygroscopicus Transglutaminase Mediated by Intein
Authors: Du Kun , Liu Zhongmei , Cui Wenjing , Zhou Li , Liu Yi , Du Guocheng , Chen Jian , Zhou Zhemin 
Published: November 2013

ABSTRACT

Microbial transglutaminase (MTG) from
Streptomyces
is naturally secreted as a zymogen (pro-MTG), which is then activated by the removal of its N-terminal proregion by additional proteases. Inteins are protein-intervening sequences that catalyze protein splicing without cofactors. In this study, a pH-dependent
Synechocystis
sp. strain PCC6803 DnaB mini-intein (SDB) was introduced into pro-MTG to simplify its activation process by controlling pH. The recombinant protein (pro-SDB-MTG) was obtained, and the activation process was determined to take 24 h at pH 7
in vitro
. To investigate the effect of the first residue in MTG on the activity and the cleavage time, two variants, pro-SDB-MTG(D1S) and pro-SDB-MTG(ΔD1), were expressed, and the activation time was found to be 6 h and 30 h, respectively. The enzymatic property and secondary structure of the recombinant MTG and two variants were similar to those of the wild type, indicating that the insertion of mini-intein did not affect the function of MTG. This insignificant effect was further illustrated by molecular dynamics simulations. This study revealed a controllable and effective strategy to regulate the activation process of pro-MTG mediated by a mini-intein, and it may have great potential for industrial MTG production.
Oral Bacterial Communities in Individuals with Type 2 Diabetes Who Live in Southern Thailand
Authors: Kampoo Kanokporn , Teanpaisan Rawee , Ledder Ruth G. , McBain Andrew J. 
Published: November 2013

ABSTRACT

Type 2 diabetes mellitus is increasingly common in Thailand and elsewhere. In the present investigation, the bacteriological composition of saliva and supragingival plaque in Thai diabetics with and without active dental caries and in nondiabetics was determined by differential culture and eubacterial DNA profiling. Potential associations between fasting blood sugar and glycosylated hemoglobin (biomarkers of current and historical glucose control, respectively) with decayed, missing, and filled teeth and with salivary
Streptococcus
and
Lactobacillus
counts were also investigated. The incidence of active dental caries was greater in the Thai diabetics than in nondiabetics, and the numbers of total streptococci and lactobacilli were significantly higher in supragingival plaque from diabetics than in nondiabetics.
Lactobacillus
counts in the saliva and supragingival plaque of diabetics with active caries were significantly higher than those in diabetics without active caries. Oral eubacterial DNA profiles of diabetic versus nondiabetic individuals and of diabetics with active caries versus those without active caries could not be readily differentiated through cluster analysis or multidimensional scaling. The elevated caries incidence in the Thai diabetics was positively associated with numbers of bacteria of the acidogenic/acid-tolerant genera
Streptococcus
and
Lactobacillus. Lactobacillus
bacterial numbers were further elevated in diabetics with active caries, although salivary eubacterial DNA profiles were not significantly altered.
Expression and Characterization of
CYP52
Genes Involved in the Biosynthesis of Sophorolipid and Alkane Metabolism from Starmerella bombicola
Authors: Huang Fong-Chin , Peter Alyssa , Schwab Wilfried 
Published: November 2013

ABSTRACT

Three cytochrome P450 monooxygenase
CYP52
gene family members were isolated from the sophorolipid-producing yeast
Starmerella bombicola
(former
Candida bombicola
), namely,
CYP52E3
,
CYP52M1
, and
CYP52N1
, and their open reading frames were cloned into the pYES2 vector for expression in
Saccharomyces cerevisiae
. The functions of the recombinant proteins were analyzed with a variety of alkane and fatty acid substrates using microsome proteins or a whole-cell system. CYP52M1 was found to oxidize C
16
to C
20
fatty acids preferentially. It converted oleic acid (C
18:1
) more efficiently than stearic acid (C
18:0
) and linoleic acid (C
18:2
) and much more effectively than α-linolenic acid (C
18:3
). No products were detected when C
10
to C
12
fatty acids were used as the substrates. Moreover, CYP52M1 hydroxylated fatty acids at their ω- and ω-1 positions. CYP52N1 oxidized C
14
to C
20
saturated and unsaturated fatty acids and preferentially oxidized palmitic acid, oleic acid, and linoleic acid. It only catalyzed ω-hydroxylation of fatty acids. Minor ω-hydroxylation activity against myristic acid, palmitic acid, palmitoleic acid, and oleic acid was shown for CYP52E3. Furthermore, the three P450s were coassayed with glucosyltransferase UGTA1. UGTA1 glycosylated all hydroxyl fatty acids generated by CYP52E3, CYP52M1, and CYP52N1. The transformation efficiency of fatty acids into glucolipids by CYP52M1/UGTA1 was much higher than those by CYP52N1/UGTA1 and CYP52E3/UGTA1. Taken together, CYP52M1 is demonstrated to be involved in the biosynthesis of sophorolipid, whereas CYP52E3 and CYP52N1 might be involved in alkane metabolism in
S. bombicola
but downstream of the initial oxidation steps.
From Genus to Phylum: Large-Subunit and Internal Transcribed Spacer rRNA Operon Regions Show Similar Classification Accuracies Influenced by Database Composition
Authors: Porras-Alfaro Andrea , Liu Kuan-Liang , Kuske Cheryl R. , Xie Gary 
Published: November 2013

ABSTRACT
We compared the classification accuracy of two sections of the fungal internal transcribed spacer (ITS) region, individually and combined, and the 5′ section (about 600 bp) of the large-subunit rRNA (LSU), using a naive Bayesian classifier and BLASTN. A hand-curated ITS-LSU training set of 1,091 sequences and a larger training set of 8,967 ITS region sequences were used. Of the factors evaluated, database composition and quality had the largest effect on classification accuracy, followed by fragment size and use of a bootstrap cutoff to improve classification confidence. The naive Bayesian classifier and BLASTN gave similar results at higher taxonomic levels, but the classifier was faster and more accurate at the genus level when a bootstrap cutoff was used. All of the ITS and LSU sections performed well (>97.7% accuracy) at higher taxonomic ranks from kingdom to family, and differences between them were small at the genus level (within 0.66 to 1.23%). When full-length sequence sections were used, the LSU outperformed the ITS1 and ITS2 fragments at the genus level, but the ITS1 and ITS2 showed higher accuracy when smaller fragment sizes of the same length and a 50% bootstrap cutoff were used. In a comparison using the larger ITS training set, ITS1 and ITS2 had very similar accuracy classification for fragments between 100 and 200 bp. Collectively, the results show that any of the ITS or LSU sections we tested provided comparable classification accuracy to the genus level and underscore the need for larger and more diverse classification training sets.
A Moderately Thermophilic Mixed Microbial Culture for Bioleaching of Chalcopyrite Concentrate at High Pulp Density
Authors: Wang Yuguang , Zeng Weimin , Qiu Guanzhou , Chen Xinhua , Zhou Hongbo 
Published: November 2013

ABSTRACT

Three kinds of samples (acid mine drainage, coal mine wastewater, and thermal spring) derived from different sites were collected in China. Thereafter, these samples were combined and then inoculated into a basal salts solution in which different substrates (ferrous sulfate, elemental sulfur, and chalcopyrite) served as energy sources. After that, the mixed cultures growing on different substrates were pooled equally, resulting in a final mixed culture. After being adapted to gradually increasing pulp densities of chalcopyrite concentrate by serial subculturing for more than 2 years, the final culture was able to efficiently leach the chalcopyrite at a pulp density of 20% (wt/vol). At that pulp density, the culture extracted 60.4% of copper from the chalcopyrite in 25 days. The bacterial and archaeal diversities during adaptation were analyzed by denaturing gradient gel electrophoresis and constructing clone libraries of the 16S rRNA gene. The results show that the culture consisted mainly of four species, including
Leptospirillum ferriphilum
,
Acidithiobacillus caldus
,
Sulfobacillus acidophilus
, and
Ferroplasma thermophilum
, before adapting to a pulp density of 4%. However,
L. ferriphilum
could not be detected when the pulp density was greater than 4%. Real-time quantitative PCR was employed to monitor the microbial dynamics during bioleaching at a pulp density of 20%. The results show that
A. caldus
was the predominant species in the initial stage, while
S. acidophilus
rather than
A. caldus
became the predominant species in the middle stage.
F. thermophilum
accounted for the greatest proportion in the final stage.
Identification and Environmental Distribution ofdcpA, Which Encodes the Reductive Dehalogenase Catalyzing the Dichloroelimination of 1,2-Dichloropropane to Propene in Organohalide-Respiring Chloroflexi
Authors: Padilla-Crespo Elizabeth , Yan Jun , Swift Cynthia , Wagner Darlene D. , Chourey Karuna , Hettich Robert L. , Ritalahti Kirsti M. , Löffler Frank E. 
Published: November 2013

ABSTRACTDehalococcoides mccartyistrains KS and RC grow with 1,2-dichloropropane (1,2-D) as an electron acceptor in enrichment cultures derived from hydrocarbon-contaminated and pristine river sediments, respectively. Transcription, expression, enzymatic, and PCR analyses implicated the reductive dehalogenase genedcpAin 1,2-D dichloroelimination to propene and inorganic chloride. Quantitative real-time PCR (qPCR) analyses demonstrated aD. mccartyicell increase during growth with 1,2-D and suggested that bothD. mccartyistrains carried a singledcpAgene copy per genome.D. mccartyistrain RC and strain KS produced 1.8 × 107± 0.1 × 107and 1.4 × 107± 0.5 × 107cells per μmol of propene formed, respectively. ThedcpAgene was identified in 1,2-D-to-propene-dechlorinating microcosms established with sediment samples collected from different geographical locations in Europe and North and South America. Clone library analysis revealed two distinctdcpAphylogenetic clusters, both of which were captured by thedcpAgene-targeted qPCR assay, suggesting that the qPCR assay is useful for site assessment and bioremediation monitoring at 1,2-D-contaminated sites.
New Model for Electron Flow for Sulfate Reduction in Desulfovibrio alaskensis G20
Authors: Keller Kimberly L. , Rapp-Giles Barbara J. , Semkiw Elizabeth S. , Porat Iris , Brown Steven D. , Wall Judy D. 
Published: November 2013

ABSTRACT

To understand the energy conversion activities of the anaerobic sulfate-reducing bacteria, it is necessary to identify the components involved in electron flow. The importance of the abundant type I tetraheme cytochrome
c
3
(TpI
c
3
) as an electron carrier during sulfate respiration was questioned by the previous isolation of a null mutation in the gene encoding TpI
c
3
,
cycA
, in
Desulfovibrio alaskensis
G20. Whereas respiratory growth of the CycA mutant with lactate and sulfate was little affected, growth with pyruvate and sulfate was significantly impaired. We have explored the phenotype of the CycA mutant through physiological tests and transcriptomic and proteomic analyses. Data reported here show that electrons from pyruvate oxidation do not reach adenylyl sulfate reductase, the enzyme catalyzing the first redox reaction during sulfate reduction, in the absence of either CycA or the type I cytochrome
c
3
:menaquinone oxidoreductase transmembrane complex, QrcABCD. In contrast to the wild type, the CycA and QrcA mutants did not grow with H
2
or formate and sulfate as the electron acceptor. Transcriptomic and proteomic analyses of the CycA mutant showed that transcripts and enzymes for the pathway from pyruvate to succinate were strongly decreased in the CycA mutant regardless of the growth mode. Neither the CycA nor the QrcA mutant grew on fumarate alone, consistent with the omics results and a redox regulation of gene expression. We conclude that TpI
c
3
and the Qrc complex are
D. alaskensis
components essential for the transfer of electrons released in the periplasm to reach the cytoplasmic adenylyl sulfate reductase and present a model that may explain the CycA phenotype through confurcation of electrons.
UV Light Inactivation of Human and Plant Pathogens in Unfiltered Surface Irrigation Water
Authors: Jones Lisa A. , Worobo Randy W. , Smart Christine D. 
Published: November 2013

ABSTRACT

Fruit and vegetable growers continually battle plant diseases and food safety concerns. Surface water is commonly used in the production of fruits and vegetables and can harbor both human- and plant-pathogenic microorganisms that can contaminate crops when used for irrigation or other agricultural purposes. Treatment methods for surface water are currently limited, and there is a need for suitable treatment options. A liquid-processing unit that uses UV light for the decontamination of turbid juices was analyzed for its efficacy in the treatment of surface waters contaminated with bacterial or oomycete pathogens, i.e.,
Escherichia coli
,
Salmonella enterica
,
Listeria monocytogenes
,
Clavibacter michiganensis
subsp.
michiganensis
,
Pseudomonas syringae
pv. tomato, and
Phytophthora capsici
. Five-strain cocktails of each pathogen, containing approximately 10
8
or 10
9
CFU/liter for bacteria or 10
4
or 10
5
zoospores/liter for
Ph. capsici
, were inoculated into aliquots of two turbid surface water irrigation sources and processed with the UV unit. Pathogens were enumerated before and after treatment. In general, as the turbidity of the water source increased, the effectiveness of the UV treatment decreased, but in all cases, 99.9% or higher inactivation was achieved. Log reductions ranged from 10.0 to 6.1 and from 5.0 to 4.2 for bacterial pathogens and
Ph. capsici
, respectively.