bluuebunny/crossref_metadata_2025_split huggingface dataset:
Autonomic control of the heart during exercise in humans: role of skeletal muscle afferents
Authors: Fisher James P. 
Published: August 2013

New findings
What is the topic of this review?
The autonomic nervous system plays a key role in bringing about the cardiovascular responses to exercise necessitated by the increased metabolic requirements of the active skeletal muscle. The complex interaction of central and peripheral neural control mechanisms evokes a decrease in parasympathetic activity and an increase sympathetic activity to the heart during exercise.
What advances does it highlight?
This review presents some of the recent insights provided by human studies into the role of mechanically and metabolically sensitive skeletal muscle afferents in the regulation of cardiac autonomic control during exercise.
The autonomic responses to exercise are orchestrated by the interactions of several central and peripheral neural mechanisms. This report focuses on the role of peripheral feedback from skeletal muscle afferents in the autonomic control of the heart during exercise in humans. Heart rate responses to passive calf stretch are abolished with cardiac parasympathetic blockade, indicating that the activation of mechanically sensitive skeletal muscle afferents (muscle mechanoreceptors) can inhibit cardiac parasympathetic activity and is likely to contribute to the increase in heart rate at the onset of exercise. Recent experiments show that the partial restriction of blood flow to the exercising skeletal muscles, to augment the activation of metabolically sensitive skeletal muscle afferents (muscle metaboreceptors) in humans, evokes an increase in heart rate that is attenuated with β1‐adrenergic blockade, thus suggesting that this response is principally mediated via an increase in cardiac sympathetic activity. Heart rate remains at resting levels during isolated activation of muscle metaboreceptors with postexercise ischaemia following hand grip, unless cardiac parasympathetic activity is inhibited, whereupon a sympathetically mediated increase in heart rate is unmasked. During postexercise ischaemia following leg cycling exercise, heart rate appears to remain elevated due to withdrawal of parasympathetic tone and/or the activation of sympathetic activity to the heart. Although the importance of skeletal muscle afferent feedback to the autonomic control of the heart during exercise is incontrovertible, the complexity of cardiac sympathetic–parasympathetic interactions and the absence of direct intraneural recordings in humans mean that it remains incompletely understood.
Impact of Land Use on Arbuscular Mycorrhizal Fungal Communities in Rural Canada
Authors: Dai Mulan , Bainard Luke D. , Hamel Chantal , Gan Yantai , Lynch Derek 
Published: August 2013

ABSTRACTThe influence of land use on soil bio-resources is largely unknown. We examined the communities of arbuscular mycorrhizal (AM) fungi in wheat-growing cropland, natural areas, and seminatural areas along roads. We sampled the Canadian prairie extensively (317 sites) and sampled 20 sites in the Atlantic maritime ecozone for comparison. The proportions of the different AM fungal taxa in the communities found at these sites varied with land use type and ecozones, based on pyrosequencing of 18S rRNA gene (rDNA) amplicons, but the lists of AM fungal taxa obtained from the different land use types and ecozones were very similar. In the prairie, the Glomeraceae family was the most abundant and diverse family of Glomeromycota, followed by the Claroideoglomeraceae, but in the Atlantic maritime ecozone, the Claroideoglomeraceae family was most abundant. In the prairie, species richness and Shannon's diversity index were highest in roadsides, whereas cropland had a higher degree of species richness than roadsides in the Atlantic maritime ecozone. The frequencies of occurrence of the different AM fungal taxa in croplands in the prairie and Atlantic maritime ecozones were highly correlated, but the AM fungal communities in these ecozones had different structures. We conclude that the AM fungal resources of soils are resilient to disturbance and that the richness of AM fungi under cropland management has been maintained, despite evidence of a structural shift imposed by this type of land use. Roadsides in the Canadian prairie are a good repository for the conservation of AM fungal diversity.
Gains of Bacterial Flagellar Motility in a Fungal World
Authors: Pion Martin , Bshary Redouan , Bindschedler Saskia , Filippidou Sevasti , Wick Lukas Y. , Job Daniel , Junier Pilar 
Published: August 2013

ABSTRACTThe maintenance of energetically costly flagella by bacteria in non-water-saturated media, such as soil, still presents an evolutionary conundrum. Potential explanations have focused on rare flooding events allowing dispersal. Such scenarios, however, overlook bacterial dispersal along mycelia as a possible transport mechanism in soils. The hypothesis tested in this study is that dispersal along fungal hyphae may lead to an increase in the fitness of flagellated bacteria and thus offer an alternative explanation for the maintenance of flagella even in unsaturated soils. Dispersal along fungal hyphae was shown for a diverse array of motile bacteria. To measure the fitness effect of dispersal, additional experiments were conducted in a model system mimicking limited dispersal, usingPseudomonas putidaKT2440 and its nonflagellated (ΔfliM) isogenic mutant in the absence or presence ofMorchella crassipesmycelia. In the absence of the fungus, flagellar motility was beneficial solely under conditions of water saturation allowing dispersal, while under conditions limiting dispersal, the nonflagellated mutant exhibited a higher level of fitness than the wild-type strain. In contrast, in the presence of a mycelial network under conditions limiting dispersal, the flagellated strain was able to disperse using the mycelial network and had a higher level of fitness than the mutant. On the basis of these results, we propose that the benefit of mycelium-associated dispersal helps explain the persistence of flagellar motility in non-water-saturated environments.
From Green to Red: Horizontal Gene Transfer of the Phycoerythrin Gene Cluster between Planktothrix Strains
Authors: Tooming-Klunderud Ave , Sogge Hanne , Rounge Trine Ballestad , Nederbragt Alexander J. , Lagesen Karin , Glöckner Gernot , Hayes Paul K. , Rohrlack Thomas , Jakobsen Kjetill S. 
Published: August 2013

ABSTRACT

Horizontal gene transfer is common in cyanobacteria, and transfer of large gene clusters may lead to acquisition of new functions and conceivably niche adaption. In the present study, we demonstrate that horizontal gene transfer between closely related
Planktothrix
strains can explain the production of the same oligopeptide isoforms by strains of different colors. Comparison of the genomes of eight
Planktothrix
strains revealed that strains producing the same oligopeptide isoforms are closely related, regardless of color. We have investigated genes involved in the synthesis of the photosynthetic pigments phycocyanin and phycoerythrin, which are responsible for green and red appearance, respectively. Sequence comparisons suggest the transfer of a functional phycoerythrin gene cluster generating a red phenotype in a strain that is otherwise more closely related to green strains. Our data show that the insertion of a DNA fragment containing the 19.7-kb phycoerythrin gene cluster has been facilitated by homologous recombination, also replacing a region of the phycocyanin operon. These findings demonstrate that large DNA fragments spanning entire functional gene clusters can be effectively transferred between closely related cyanobacterial strains and result in a changed phenotype. Further, the results shed new light on the discussion of the role of horizontal gene transfer in the sporadic distribution of large gene clusters in cyanobacteria, as well as the appearance of red and green strains.
Bifidobacterium animalis subsp. lactis ATCC 27673 Is a Genomically Unique Strain within Its Conserved Subspecies
Authors: Loquasto Joseph R. , Barrangou Rodolphe , Dudley Edward G. , Stahl Buffy , Chen Chun , Roberts Robert F. 
Published: August 2013

ABSTRACT

Many strains of
Bifidobacterium animalis
subsp.
lactis
are considered health-promoting probiotic microorganisms and are commonly formulated into fermented dairy foods. Analyses of previously sequenced genomes of
B. animalis
subsp.
lactis
have revealed little genetic diversity, suggesting that it is a monomorphic subspecies. However, during a multilocus sequence typing survey of
Bifidobacterium
, it was revealed that
B. animalis
subsp.
lactis
ATCC 27673 gave a profile distinct from that of the other strains of the subspecies. As part of an ongoing study designed to understand the genetic diversity of this subspecies, the genome of this strain was sequenced and compared to other sequenced genomes of
B. animalis
subsp.
lactis
and
B. animalis
subsp.
animalis
. The complete genome of ATCC 27673 was 1,963,012 bp, contained 1,616 genes and 4 rRNA operons, and had a G+C content of 61.55%. Comparative analyses revealed that the genome of ATCC 27673 contained six distinct genomic islands encoding 83 open reading frames not found in other strains of the same subspecies. In four islands, either phage or mobile genetic elements were identified. In island 6, a novel clustered regularly interspaced short palindromic repeat (CRISPR) locus which contained 81 unique spacers was identified. This type I-E CRISPR-
cas
system differs from the type I-C systems previously identified in this subspecies, representing the first identification of a different system in
B. animalis
subsp.
lactis
. This study revealed that ATCC 27673 is a strain of
B. animalis
subsp.
lactis
with novel genetic content and suggests that the lack of genetic variability observed is likely due to the repeated sequencing of a limited number of widely distributed commercial strains.
Visualization of Imbalances in Sulfur Assimilation and Synthesis of Sulfur-Containing Amino Acids at the Single-Cell Level
Authors: Hoffmann Kristina , Grünberger Alexander , Lausberg Frank , Bott Michael , Eggeling Lothar 
Published: August 2013

ABSTRACT

We describe genetically encoded sensors which transmit elevated cytosolic concentrations of O-acetyl serine (OAS) and O-acetyl homoserine (OAH)—intermediates of
l
-cysteine and
l
-methionine synthesis—into an optical output. The sensor pSenOAS3 elicits 7.5-fold-increased fluorescence in cultures of a
Corynebacterium glutamicum
strain that excrete
l
-cysteine. Determination of the cytosolic OAS concentration revealed an increase to 0.13 mM, whereas the concentration in the reference strain was below the detection limit, indicating that incorporation of assimilatory sulfur is limited in the strain studied. In another strain, overexpression of
metX
encoding homoserine acetyltransferase resulted in an 8-fold increase in culture fluorescence at a cytosolic OAH concentration of 0.76 mM. We also assayed for consequences of extracellular sulfur supply and observed a graded fluorescence increase at decreasing sulfur concentrations below 400 μM. Overall, this demonstrates the usefulness of the sensors for monitoring intracellular sulfur availability. The sensors also enable monitoring at the single-cell level, and since related and close homologs of the transcription factor used in the constructed sensors are widespread among bacteria, this technology offers a new possibility of assaying
in vivo
for sulfur limitation and of doing this at the single-cell level.
Phylogenetic and Chemical Diversity of a Hybrid-Isoprenoid-Producing Streptomycete Lineage
Authors: Gallagher Kelley A. , Rauscher Kristin , Pavan Ioca Laura , Jensen Paul R. 
Published: August 2013

ABSTRACT

Streptomyces
species dedicate a large portion of their genomes to secondary metabolite biosynthesis. A diverse and largely marine-derived lineage within this genus has been designated MAR4 and identified as a prolific source of hybrid isoprenoid (HI) secondary metabolites. These terpenoid-containing compounds are common in nature but rarely observed as bacterial secondary metabolites. To assess the phylogenetic diversity of the MAR4 lineage, complementary culture-based and culture-independent techniques were applied to marine sediment samples collected off the Channel Islands, CA. The results, including those from an analysis of publically available sequence data and strains isolated as part of prior studies, placed 40 new strains in the MAR4 clade, of which 32 originated from marine sources. When combined with sequences cloned from environmental DNA, 28 MAR4 operational taxonomic units (0.01% genetic distance) were identified. Of these, 82% consisted exclusively of either cloned sequences or cultured strains, supporting the complementarity of these two approaches. Chemical analyses of diverse MAR4 strains revealed the production of five different HI structure classes. All 21 MAR4 strains tested produced at least one HI class, with most strains producing from two to four classes. The two major clades within the MAR4 lineage displayed distinct patterns in the structural classes and the number and amount of HIs produced, suggesting a relationship between taxonomy and secondary metabolite production. The production of HI secondary metabolites appears to be a phenotypic trait of the MAR4 lineage, which represents an emerging model with which to study the ecology and evolution of HI biosynthesis.
Effect of Electropermeabilization by Ohmic Heating for Inactivation of Escherichia coli O157:H7, Salmonella enterica Serovar Typhimurium, and Listeria monocytogenes in Buffered Peptone Water and Apple Juice
Authors: Park Il-Kyu , Kang Dong-Hyun 
Published: August 2013

ABSTRACT

The effect of electric field-induced ohmic heating for inactivation of
Escherichia coli
O157:H7,
Salmonella enterica
serovar Typhimurium, and
Listeria monocytogenes
in buffered peptone water (BPW) (pH 7.2) and apple juice (pH 3.5; 11.8 °Brix) was investigated in this study. BPW and apple juice were treated at different temperatures (55°C, 58°C, and 60°C) and for different times (0, 10, 20, 25, and 30 s) by ohmic heating compared with conventional heating. The electric field strength was fixed at 30 V/cm and 60 V/cm for BPW and apple juice, respectively. Bacterial reduction resulting from ohmic heating was significantly different (
P
< 0.05) from that resulting from conventional heating at 58°C and 60°C in BPW and at 55°C, 58°C, and 60°C in apple juice for intervals of 0, 10, 20, 25, and 30 s. These results show that electric field-induced ohmic heating led to additional bacterial inactivation at sublethal temperatures. Transmission electron microscopy (TEM) observations and the propidium iodide (PI) uptake test were conducted after treatment at 60°C for 0, 10, 20, 25 and 30 s in BPW to observe the effects on cell permeability due to electroporation-caused cell damage. PI values when ohmic and conventional heating were compared were significantly different (
P
< 0.05), and these differences increased with increasing levels of inactivation of three food-borne pathogens. These results demonstrate that ohmic heating can more effectively reduce bacterial populations at reduced temperatures and shorter time intervals, especially in acidic fruit juices such as apple juice. Therefore, loss of quality can be minimized in a pasteurization process incorporating ohmic heating.
Probing the Functional Diversity of Global Pristine Soil Communities with 3-Chlorobenzoate Reveals that Communities of Generalists Dominate Catabolic Transformation
Authors: Rhodes Albert N. , Fulthorpe Roberta R. , Tiedje James M. 
Published: August 2013

ABSTRACT
Understanding of functional diversity of microbial populations has lagged description of their molecular diversity. Differences in substrate specificity, kinetics, products, and regulation can dramatically influence phenotypic variation among closely related strains, features that are missed when the strains studied are the fastest-growing and most easily isolated from serial enrichments. To investigate the broader bacterial diversity underlying degradation of anthropogenic chemicals in nature, we studied the 3-chlorobenzoate (3-CBA) degradation rate in a collection of aerobic 3-CBA degraders previously isolated from undisturbed soils in two representative ecosystems: (i) Mediterranean sclerophyllous woodlands in California, Chile, South Africa, and Australia and (ii) boreal forests in Canada and Russia. The majority of isolates degraded 3-CBA slowly and did not completely mineralize 1.0 mM 3-CBA within 1 week. Those with intermediate degradation rates had incomplete degradation pathways and produced colored intermediates indicative of chlorocatechol, a product likely metabolized by other members of the community. About 10% of the isolates grew rapidly and mineralized greater than 90% of the 3-CBA, but because of population heterogeneity in soil, they are likely not large contributors to a soil's total transformation capacity. This suggests that xenobiotic degradation in nature is carried out by a community of cometabolic generalists and not by the efficient specialists that have been traditionally studied in the laboratory. A subset of 58 genotypically distinct strains able to degrade >80% of the 3-CBA was examined for their catabolic versatility using 45 different compounds: mono- and dichlorinated benzoates, phenols, anilines, toluenes, nitrobenzenes, chlorobenzenes, and 2,4-dichlorophenoxyacetic acid. The isolates degraded from 2 to more than 30 compounds with a median of 7, but there was no correlation to habitat of isolation or 3-CBA activity. However, these findings were indicative of finer-scale functional diversity.
The Genome of the Alga-Associated Marine Flavobacterium Formosa agariphila KMM 3901
T
Reveals a Broad Potential for Degradation of Algal Polysaccharides
Authors: Mann Alexander J. , Hahnke Richard L. , Huang Sixing , Werner Johannes , Xing Peng , Barbeyron Tristan , Huettel Bruno , Stüber Kurt , Reinhardt Richard , Harder Jens , Glöckner Frank Oliver , Amann Rudolf I. , Teeling Hanno 
Published: August 2013

ABSTRACT

In recent years, representatives of the
Bacteroidetes
have been increasingly recognized as specialists for the degradation of macromolecules.
Formosa
constitutes a
Bacteroidetes
genus within the class
Flavobacteria
, and the members of this genus have been found in marine habitats with high levels of organic matter, such as in association with algae, invertebrates, and fecal pellets. Here we report on the generation and analysis of the genome of the type strain of
Formosa agariphila
(KMM 3901
T
), an isolate from the green alga
Acrosiphonia sonderi
.
F. agariphila
is a facultative anaerobe with the capacity for mixed acid fermentation and denitrification. Its genome harbors 129 proteases and 88 glycoside hydrolases, indicating a pronounced specialization for the degradation of proteins, polysaccharides, and glycoproteins. Sixty-five of the glycoside hydrolases are organized in at least 13 distinct polysaccharide utilization loci, where they are clustered with TonB-dependent receptors, SusD-like proteins, sensors/transcription factors, transporters, and often sulfatases. These loci play a pivotal role in bacteroidetal polysaccharide biodegradation and in the case of
F. agariphila
revealed the capacity to degrade a wide range of algal polysaccharides from green, red, and brown algae and thus a strong specialization of toward an alga-associated lifestyle. This was corroborated by growth experiments, which confirmed usage particularly of those monosaccharides that constitute the building blocks of abundant algal polysaccharides, as well as distinct algal polysaccharides, such as laminarins, xylans, and κ-carrageenans.
Cloning and Heterologous Expression of the Thioviridamide Biosynthesis Gene Cluster from Streptomyces olivoviridis
Authors: Izawa Masumi , Kawasaki Takashi , Hayakawa Yoichi 
Published: August 2013

ABSTRACT

Thioviridamide is a unique peptide antibiotic containing five thioamide bonds from
Streptomyces olivoviridis
. Draft genome sequencing revealed a gene (the
tvaA
gene) encoding the thioviridamide precursor peptide. The thioviridamide biosynthesis gene cluster was identified by heterologous production of thioviridamide in
Streptomyces lividans
.
An Improved PCR-Restriction Fragment Length Polymorphism (RFLP) Method for the Identification of
cry1
-Type Genes
Authors: Shu Changlong , Liu Dongming , Zhou Zishan , Cai Jilin , Peng Qi , Gao Jiguo , Song Fuping , Zhang Jie 
Published: August 2013

ABSTRACT

The
cry1
-type genes of
Bacillus thuringiensis
represent the largest
cry
gene family, which contains 50 distinct holotypes. It is becoming more and more difficult to identify
cry1
-type genes using current methods because of the increasing number of
cry1
-type genes. In the present study, an improved PCR-restriction fragment length polymorphism (PCR-RFLP) method which can distinguish 41 holotypes of
cry1
-type genes was developed. This improved method was used to identify
cry1
-type genes in 20
B. thuringiensis
strains that are toxic to lepidoptera. The results showed that the improved method can efficiently identify single and clustered
cry1
-type genes and can be used to evaluate
cry1
-type genes in novel strain collections of
B. thuringiensis
. Among the detected
cry1
-type genes, we identified four novel genes,
cry1Ai
,
cry1Bb
,
cry1Ja
, and
cry1La
. The bioassay results from the expressed products of the four novel
cry
genes showed that Cry1Ai2, Cry1Bb2, and Cry1Ja2 were highly toxic against
Plutella xylostella
, whereas Cry1La2 exhibited no activity. Moreover, Cry1Ai2 had good lethal activity against
Ostrinia furnacalis
,
Hyphantria cunea
,
Chilo suppressalis
, and
Bombyx mori
larvae and considerable weight loss activity against
Helicoverpa armigera
.
Pseudoalteromonas spp. Serve as Initial Bacterial Attractants in Mesocosms of Coastal Waters but Have Subsequent Antifouling Capacity in Mesocosms and when Embedded in Paint
Authors: Bernbom Nete , Ng Yoke Yin , Olsen Stefan Møller , Gram Lone 
Published: August 2013

ABSTRACT

The purpose of the present study was to determine if the monoculture antifouling effect of several pigmented pseudoalteromonads was retained in
in vitro
mesocosm systems using natural coastal seawater and when the bacteria were embedded in paint used on surfaces submerged in coastal waters.
Pseudoalteromonas piscicida
survived on a steel surface and retained antifouling activity for at least 53 days in sterile seawater, whereas
P. tunicata
survived and had antifouling activity for only 1 week. However, during the first week, all
Pseudoalteromonas
strains facilitated rather than prevented bacterial attachment when used to coat stainless steel surfaces and submerged in mesocosms with natural seawater. The bacterial density on surfaces coated with sterile growth medium was 10
5
cells/cm
2
after 7 days, whereas counts on surfaces precoated with
Pseudoalteromonas
were significantly higher, at 10
6
to 10
8
cells/cm
2
. However, after 53 days, seven of eight
Pseudoalteromonas
strains had reduced total bacterial adhesion compared to the control.
P. piscicida
,
P. antarctica
, and
P. ulvae
remained on the surface, at levels similar to those in the initial coating, whereas
P. tunicata
could not be detected. Larger fouling organisms were observed on all plates precoated with
Pseudoalteromonas
; however, plates coated only with sterile growth medium were dominated by a bacterial biofilm. Suspensions of a
P. piscicida
strain and a
P. tunicata
strain were incorporated into ship paints (Hempasil x3 87500 and Hempasil 77500) used on plates that were placed at the Hempel A/S test site in Jyllinge Harbor. For the first 4 months, no differences were observed between control plates and treated plates, but after 5 to 6 months, the control plates were more fouled than the plates with pseudoalteromonad-based paint. Our study demonstrates that no single laboratory assay can predict antifouling effects and that a combination of laboratory and real-life methods must be used to determine the potential antifouling capability of new agents or organisms.