bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Limits of Kinship Mobilizations and the (A)politics of Human Rights inArgentina
Authors: Gandsman Ari 
Published: July 2012

ResúmenOrganismos de derechos humanos como Las Madres y Las Abuelas de Plaza de Mayo constituyen modelos importantes de activismo ciudadanía en América Latina. Como revelan sus nombres, son modelos particulares de activismo organizado en categorías de parentesco y en gran medida biológicamente definido con lazos afectivos. En lugar de ver a estas organizaciones como la politización de lo que convencionalmente se entiende como el terreno apolítico de la maternidad, en este artículo muestro que lo contrario también puede ocurrir. Movimientos que enfatizan los lazos biológicos y las identidades adquiridas también tienen efectos de despolitización. Porque se percibe que sus actividades radican fuera de la política. Privilegiar las relaciones afectivas como un modo de organización – un evento necesario en la evolución de estos grupos durante la dictadura – ha dado lugar a una paradoja en el desarrollo de estos grupos, los cuales por un lado evitan ser percibidos como participantes de la actividad política, a pesar de desarrollar explícitamente una actividad política.
Night Becomes Day: Carnival, Contested Spaces, and the Black Movement in Bahia
Authors: Williamson Kenneth 
Published: July 2012

AbstractThis article details the cultural politics surrounding carnival in Salvador, Bahia, Brazil, between 1995 and 1999, including the experiences and meanings of carnival, the struggle over Afro‐Brazilian culture, and wealth generated from carnival. The black movement utilizes carnival as a highly visible site of contestation and protest against racism in Brazil. However, the movement simultaneously struggles with issues of co‐optation, especially by African carnival groups, demonstrating the tensions in the interrelationship between culture and politics. Black movement activists’ stories and experiences reveal the micropolitics of the movement and individuals engaged in politics and identity.
High-Salt Stress Conditions Increase the pAW63 Transfer Frequency in Bacillus thuringiensis
Authors: Beuls Elise , Modrie Pauline , Deserranno Cï¿½dric , Mahillon Jacques 
Published: July 2012

ABSTRACT

Conjugation experiments with
Bacillus thuringiensis
and transfer kinetics demonstrated that salt stress has a positive impact on plasmid transfer efficiency. Compared to standard osmotic conditions (0.5% NaCl), plasmid transfer occurred more rapidly, and at higher frequencies (>100-fold), when bacteria were exposed to a high-salt stress (5% NaCl) in liquid brain heart infusion (BHI). Under milder salt conditions (2.5% NaCl), only a 10-fold effect was observed in Luria-Bertani broth and no difference was detected in BHI. These observations are particularly relevant in the scope of potential gene exchanges among members of the
Bacillus cereus
group, which includes food-borne contaminants and pathogens.
Regulatable Vectors for Environmental Gene Expression in Alphaproteobacteria
Authors: Tett Adrian J. , Rudder Steven J. , Bourdï¿½s Alexandre , Karunakaran Ramakrishnan , Poole Philip S. 
Published: July 2012

ABSTRACT

Two expression vectors utilizing the inducible taurine promoter (
tauAp
) were developed. Plasmid pLMB51 is a stable low-copy vector enabling expression in the environment and
in planta
. The higher copy number pLMB509 enables BD restriction-independent cloning, expression, and purification of polyhistidine-tagged proteins.
Roles of Four Putative DEAD-Box RNA Helicase Genes in Growth of Listeria monocytogenes EGD-e under Heat, pH, Osmotic, Ethanol, and Oxidative Stress Conditions
Authors: Markkula Annukka , Lindstrï¿½m Miia , Johansson Per , Bjï¿½rkroth Johanna , Korkeala Hannu 
Published: July 2012

ABSTRACTTo examine the role of the four putative DEAD-box RNA helicase genes ofListeria monocytogenesEGD-e in stress tolerance, the growth of the Δlmo0866, Δlmo1246, Δlmo1450, and Δlmo1722deletion mutant strains at 42.5ï¿½C, at pH 5.6 or pH 9.4, in 6% NaCl, in 3.5% ethanol, and in 5 mM H2O2was studied. Restricted growth of the Δlmo0866deletion mutant strain in 3.5% ethanol suggests that Lmo0866 contributes to ethanol stress tolerance ofL. monocytogenesEGD-e. The Δlmo1450mutant strain showed negligible growth at 42.5ï¿½C, at pH 9.4, and in 5 mM H2O2and a lower maximum growth temperature than the wild-type EGD-e, suggesting that Lmo1450 is involved in the tolerance ofL. monocytogenesEGD-e to heat, alkali, and oxidative stresses. The altered stress tolerance of the Δlmo0866and Δlmo1450deletion mutant strains did not correlate with changes in relative expression levels oflmo0866andlmo1450genes under corresponding stresses, suggesting that Lmo0866- and Lmo1450-dependent tolerance to heat, alkali, ethanol, or oxidative stress is not regulated at the transcriptional level. Growth of the Δlmo1246and Δlmo1722deletion mutant strains did not differ from that of the wild-type EGD-e under any of the conditions tested, suggesting that Lmo1246 and Lmo1722 have no roles in the growth ofL. monocytogenesEGD-e under heat, pH, osmotic, ethanol, or oxidative stress. This study shows that the putative DEAD-box RNA helicase geneslmo0866andlmo1450play important roles in tolerance ofL. monocytogenesEGD-e to ethanol, heat, alkali, and oxidative stresses.
Biological Role of Pigment Production for the Bacterial Phytopathogen Pantoea stewartii subsp. stewartii
Authors: Mohammadi Mojtaba , Burbank Lindsey , Roper M. Caroline 
Published: July 2012

ABSTRACT

Pantoea stewartii
subsp.
stewartii
, the causal agent of Stewart's wilt of sweet corn, produces a yellow carotenoid pigment. A nonpigmented mutant was selected from a bank of mutants generated by random transposon mutagenesis. The transposon insertion site was mapped to the
crtB
gene, encoding a putative phytoene synthase, an enzyme involved in the early steps of carotenoid biosynthesis. We demonstrate here that the carotenoid pigment imparts protection against UV radiation and also contributes to the complete antioxidant pathway of
P. stewartii
. Moreover, production of this pigment is regulated by the EsaI/EsaR quorum-sensing system and significantly contributes to the virulence of the pathogen
in planta
.
Isolated Microbial Single Cells and Resulting Micropopulations Grow Faster in Controlled Environments
Authors: Dusny Christian , Fritzsch Frederik Sven Ole , Frick Oliver , Schmid Andreas 
Published: July 2012

ABSTRACT

Singularized cells of
Pichia pastoris
,
Hansenula polymorpha
, and
Corynebacterium glutamicum
displayed specific growth rates under chemically and physically constant conditions that were consistently higher than those obtained in populations. This highlights the importance of single-cell analyses by uncoupling physiology and the extracellular environment, which is now possible using the Envirostat 2.0 concept.
Mechanisms by Which Ambient Humidity May Affect Viruses in Aerosols
Authors: Yang Wan , Marr Linsey C. 
Published: July 2012

ABSTRACT
Many airborne viruses have been shown to be sensitive to ambient humidity, yet the mechanisms responsible for this phenomenon remain elusive. We review multiple hypotheses, including water activity, surface inactivation, and salt toxicity, that may account for the association between humidity and viability of viruses in aerosols. We assess the evidence and limitations for each hypothesis based on findings from virology, aerosol science, chemistry, and physics. In addition, we hypothesize that changes in pH within the aerosol that are induced by evaporation may trigger conformational changes of the surface glycoproteins of enveloped viruses and subsequently compromise their infectivity. This hypothesis may explain the differing responses of enveloped viruses to humidity. The precise mechanisms underlying the relationship remain largely unverified, and attaining a complete understanding of them will require an interdisciplinary approach.
Mycobacterial Shuttle Vectors Designed for High-Level Protein Expression in Infected Macrophages
Authors: Eitson Jennifer L. , Medeiros Jennifer J. , Hoover Ashley R. , Srivastava Shashikant , Roybal Kole T. , Aï¿½nsa Josï¿½ A. , Hansen Eric J. , Gumbo Tawanda , van Oers Nicolai S. C. 
Published: July 2012

ABSTRACT

Mycobacterial shuttle vectors contain dual origins of replication for growth in both
Escherichia coli
and mycobacteria. One such vector, pSUM36, was re-engineered for high-level protein expression in diverse bacterial species. The modified vector (pSUM-
kan
-MCS2) enabled green fluorescent protein expression in
E. coli
,
Mycobacterium smegmatis
, and
M. avium
at levels up to 50-fold higher than that detected with the parental vector, which was originally developed with a
lacZ
α promoter. This high-level fluorescent protein expression allowed easy visualization of
M. smegmatis
and
M. avium
in infected macrophages. The
M. tuberculosis
gene
esat-6
was cloned in place of the green fluorescence protein gene (
gfp
) to determine the impact of ESAT-6 on the innate inflammatory response. The modified vector (pSUM-
kan
-MCS2) yielded high levels of ESAT-6 expression in
M. smegmatis
. The ability of ESAT-6 to suppress innate inflammatory pathways was assayed with a novel macrophage reporter cell line, designed with an interleukin-6 (IL-6) promoter-driven GFP cassette. This stable cell line fluoresces in response to diverse mycobacterial strains and stimuli, such as lipopolysaccharide.
M. smegmatis
clones expressing high levels of ESAT-6 failed to attenuate IL-6-driven GFP expression. Pure ESAT-6, produced in
E. coli
, was insufficient to suppress a strong inflammatory response elicited by
M. smegmatis
or lipopolysaccharide, with ESAT-6 itself directly activating the IL-6 pathway. In summary, a pSUM-protein expression vector and a mammalian IL-6 reporter cell line provide new tools for understanding the pathogenic mechanisms deployed by various mycobacterial species.
TetR-Based Gene Regulation Systems for Francisella tularensis
Authors: LoVullo Eric D. , Miller Cheryl N. , Pavelka Martin S. , Kawula Thomas H. 
Published: July 2012

ABSTRACT

There are a number of genetic tools available for studying
Francisella tularensis
, the etiological agent of tularemia; however, there is no effective inducible or repressible gene expression system. Here, we describe inducible and repressible gene expression systems for
F. tularensis
based on the Tet repressor, TetR. For the inducible system, a
tet
operator sequence was cloned into a modified
F. tularensis groESL
promoter sequence and carried in a plasmid that constitutively expressed TetR. To monitor regulation the luminescence operon,
luxCDABE
, was cloned under the hybrid
Francisella
tetracycline-regulated promoter (
FTRp
), and transcription was initiated with addition of anhydrotetracycline (ATc), which binds TetR and alleviates TetR association with
tetO.
Expression levels measured by luminescence correlated with ATc inducer concentrations ranging from 20 to 250 ng ml
−1
. In the absence of ATc, luminescence was below the level of detection. The inducible system was also functional during the infection of J774A.1 macrophages, as determined by both luminescence and rescue of a mutant strain with an intracellular growth defect. The repressible system consists of
FTRp
regulated by a reverse TetR mutant (revTetR), TetR r1.7. Using this system with the
lux
reporter, the addition of ATc resulted in decreased luminescence, while in the absence of ATc the level of luminescence was not significantly different from that of a construct lacking TetR r1.7. Utilizing both systems, the essentiality of SecA, the protein translocase ATPase, was confirmed, establishing that they can effectively regulate gene expression. These two systems will be invaluable in exploring
F. tularensis
protein function.
Intact Polar and Core Glycerol Dibiphytanyl Glycerol Tetraether Lipids of Group I.1a and I.1b Thaumarchaeota in Soil
Authors: Sinninghe Damstï¿½ Jaap S. , Rijpstra W. Irene C. , Hopmans Ellen C. , Jung Man-Young , Kim Jong-Geol , Rhee Sung-Keun , Stieglmeier Michaela , Schleper Christa 
Published: July 2012

ABSTRACT

Ecological studies of thaumarchaeota often apply glycerol dibiphytanyl glycerol tetraether (GDGT)-based intact membrane lipids. However, these components have only been characterized for thaumarchaeota from aquatic environments. Thaumarchaeota have been shown to play an important role in the nitrogen cycle in soil as ammonium oxidizers, and GDGTs are common lipids encountered in soil. We report the core and intact polar lipid (IPL) GDGTs produced by three newly available thaumarchaeota isolated from grassland soil in Austria (“
Nitrososphaera viennensis
,” group I.1b) and enriched from agricultural soils in South Korea (“
Candidatus
Nitrosoarchaeum koreensis” MY1, group I.1a; and “
Candidatus
Nitrososphaera” strain JG1, group I.1b). The soil thaumarchaeota all synthesize crenarchaeol as their major core GDGT, in agreement with the fact that crenarchaeol has also been detected in thaumarchaeota from aquatic environments. The crenarchaeol regioisomer apparently is produced in significant quantities only by soil thaumarchaeota of the I.1b subgroup. In addition, GDGTs with 0 to 4 cyclopentane moieties and GDGTs containing an additional hydroxyl group were detected. The IPL head groups of their membrane lipids comprised mainly monohexose, dihexose, trihexose, phosphohexose, and hexose-phosphohexose moieties. The hexose-phosphohexose head group bound to crenarchaeol occurred in all soil thaumarchaeota, and this IPL is at present the only lipid that is detected in all thaumarchaeota analyzed so far. This specificity and its lability indicate that it is the most suitable biomarker lipid to trace living thaumarchaeota. This study, in combination with previous studies, also suggests that hydroxylated GDGTs occur in the I.1a, but not in the I.1b, subgroup of the thaumarchaeota.
Involvement of the Major Capsid Protein and Two Early-Expressed Phage Genes in the Activity of the Lactococcal Abortive Infection Mechanism AbiT
Authors: Labrie Simon J. , Tremblay Denise M. , Moisan Maxim , Villion Manuela , Magadï¿½n Alfonso H. , Campanacci Valï¿½rie , Cambillau Christian , Moineau Sylvain 
Published: July 2012

ABSTRACT

The dairy industry uses the mesophilic, Gram-positive, lactic acid bacterium (LAB)
Lactococcus lactis
to produce an array of fermented milk products. Milk fermentation processes are susceptible to contamination by virulent phages, but a plethora of phage control strategies are available. One of the most efficient is to use LAB strains carrying phage resistance systems such as abortive infection (Abi) mechanisms. Yet, the mode of action of most Abi systems remains poorly documented. Here, we shed further light on the antiviral activity of the lactococcal AbiT system. Twenty-eight AbiT-resistant phage mutants derived from the wild-type AbiT-sensitive lactococcal phages p2, bIL170, and P008 were isolated and characterized. Comparative genomic analyses identified three different genes that were mutated in these virulent AbiT-insensitive phage derivatives:
e14
(bIL170 [
e14
bIL170
]),
orf41
(P008 [
orf41
P008
]), and
orf6
(p2 [
orf6
p2
] and P008 [
orf6
P008
]). The genes
e14
bIL170
and
orf41
P008
are part of the early-expressed genomic region, but bioinformatic analyses did not identify their putative function.
orf6
is found in the phage morphogenesis module. Antibodies were raised against purified recombinant ORF6, and immunoelectron microscopy revealed that it is the major capsid protein (MCP). Coexpression in
L. lactis
of ORF6
p2
and ORF5
p2
, a protease, led to the formation of procapsids. To our knowledge, AbiT is the first Abi system involving distinct phage genes.
Chemotaxis of Marinobacter adhaerens and Its Impact on Attachment to the Diatom Thalassiosira weissflogii
Authors: Sonnenschein Eva C. , Syit Desalegne Abebew , Grossart Hans-Peter , Ullrich Matthias S. 
Published: July 2012

ABSTRACT

Alga-bacterium interactions are crucial for aggregate formation and carbon cycling in aquatic systems. To understand the initiation of these interactions, we investigated bacterial chemotaxis within a bilateral model system.
Marinobacter adhaerens
HP15 has been demonstrated to attach to the diatom
Thalassiosira weissflogii
and induce transparent exopolymeric particle and aggregate formation.
M. adhaerens
possesses one polar flagellum and is highly motile. Bacterial cells were attracted to diatom cells, as demonstrated by addition of diatom cell homogenate or diatom culture supernatant to soft agar, suggesting that chemotaxis might be important for the interaction of
M. adhaerens
with diatoms. Three distinct chemotaxis-associated gene clusters were identified in the genome sequence of
M. adhaerens
, with the clusters showing significant sequence similarities to those of
Pseudomonas aeruginosa
PAO1. Mutations in the genes
cheA
,
cheB
,
chpA
, and
chpB
, which encode histidine kinases and methylesterases and which are putatively involved in either flagellum-associated chemotaxis or pilus-mediated twitching motility, were generated and mutants with the mutations were phenotypically analyzed. Δ
cheA
and Δ
cheB
mutants were found to be swimming deficient, and all four mutants were impaired in biofilm formation on abiotic surfaces. Comparison of the HP15 wild type and its chemotaxis mutants in cocultures with the diatom revealed that the fraction of bacteria attaching to the diatom decreased significantly for mutants in comparison to that for the wild type. Our results highlight the importance of
M. adhaerens
chemotaxis in initiation of its interaction with the diatom. In-depth knowledge of these basic processes in interspecies interactions is pivotal to obtain a systematic understanding of organic matter flux and nutrient cycling in marine ecosystems.
Heat Shock Protein 90 Is Required for Conidiation and Cell Wall Integrity in Aspergillus fumigatus
Authors: Lamoth Frédéric , Juvvadi Praveen R. , Fortwendel Jarrod R. , Steinbach William J. 
Published: July 2012

ABSTRACT

Heat shock protein 90 (Hsp90) is a eukaryotic molecular chaperone. Its involvement in the resistance of
Candida albicans
to azole and echinocandin antifungals is well established. However, little is known about Hsp90's function in the filamentous fungal pathogen
Aspergillus fumigatus
. We investigated the role of Hsp90 in
A. fumigatus
by genetic repression and examined its cellular localization under various stress conditions. Failure to generate a deletion strain of
hsp90
suggested that it is essential. Genetic repression of Hsp90 was achieved by an inducible nitrogen-dependent promoter (
pniiA
-Hsp90) and led to decreased spore viability, decreased hyphal growth, and severe defects in germination and conidiation concomitant with the downregulation of the conidiation-specific transcription factors
brlA
,
wetA
, and
abaA
. Hsp90 repression potentiated the effect of cell wall inhibitors affecting the β-glucan structure of the cell wall (caspofungin, Congo red) and of the calcineurin inhibitor FK506, supporting a role in regulating cell wall integrity pathways. Moreover, compromising Hsp90 abolished the paradoxical effect of caspofungin. Pharmacological inhibition of Hsp90 by geldanamycin and its derivatives (17-AAG and 17-DMAG) resulted in similar effects. C-terminal green fluorescent protein (GFP) tagging of Hsp90 revealed mainly cytosolic distribution under standard growth conditions. However, treatment with caspofungin resulted in Hsp90 accumulation at the cell wall and at sites of septum formation, further highlighting its role in cell wall stress compensatory mechanisms. Targeting Hsp90 with fungal-specific inhibitors to cripple stress response compensatory pathways represents an attractive new antifungal strategy.
Hfq Influences Multiple Transport Systems and Virulence in the Plant Pathogen Agrobacterium tumefaciens
Authors: Wilms Ina , Möller Philip , Stock Anna-Maria , Gurski Rosemarie , Lai Erh-Min , Narberhaus Franz 
Published: July 2012

ABSTRACTThe Hfq protein mediates gene regulation by small RNAs (sRNAs) in about 50% of all bacteria. Depending on the species, phenotypic defects of anhfqmutant range from mild to severe. Here, we document that the purified Hfq protein of the plant pathogen and natural genetic engineerAgrobacterium tumefaciensbinds to the previously described sRNA AbcR1 and its target mRNAatu2422, which codes for the substrate binding protein of an ABC transporter taking up proline and γ-aminobutyric acid (GABA). Several other ABC transporter components were overproduced in anhfqmutant compared to their levels in the parental strain, suggesting that Hfq plays a major role in controlling the uptake systems and metabolic versatility ofA. tumefaciens. Thehfqmutant showed delayed growth, altered cell morphology, and reduced motility. Although the DNA-transferring type IV secretion system was produced, tumor formation by the mutant strain was attenuated, demonstrating an important contribution of Hfq to plant transformation byA. tumefaciens.
Seventeen Sxy-Dependent Cyclic AMP Receptor Protein Site-Regulated Genes Are Needed for Natural Transformation in Haemophilus influenzae
Authors: Sinha Sunita , Mell Joshua C. , Redfield Rosemary J. 
Published: July 2012

ABSTRACTNatural competence is the ability of bacteria to actively take up extracellular DNA. This DNA can recombine with the host chromosome, transforming the host cell and altering its genotype. InHaemophilus influenzae, natural competence is induced by energy starvation and the depletion of nucleotide pools. This induces a 26-gene competence regulon (Sxy-dependent cyclic AMP receptor protein [CRP-S] regulon) whose expression is controlled by two regulators, CRP and Sxy. The role of most of the CRP-S genes in DNA uptake and transformation is not known. We have therefore created in-frame deletions of each CRP-S gene and studied their competence phenotypes. All but one gene (ssb) could be deleted. Although none of the remaining CRP-S genes were required for growth in rich medium or survival under starvation conditions, DNA uptake and transformation were abolished or reduced in most of the mutants. Seventeen genes were absolutely required for transformation, with 14 of these genes being specifically required for the assembly and function of the type IV pilus DNA uptake machinery. Only five genes were dispensable for both competence and transformation. This is the first competence regulon for which all genes have been mutationally characterized.
Cellulose Degradation by Sulfolobus solfataricus Requires a Cell-Anchored Endo-β-1-4-Glucanase
Authors: Girfoglio Michele , Rossi Mosé , Cannio Raffaele 
Published: July 2012

ABSTRACTA sequence encoding a putative extracellular endoglucanase (sso1354) was identified in the complete genome sequence ofSulfolobus solfataricus. The encoded protein shares signature motifs with members of glycoside hydrolases family 12. After an unsuccessful first attempt at cloning the full-length coding sequences inEscherichia coli, an active but unstable recombinant enzyme lacking a 27-residue N-terminal sequence was generated. This 27-amino-acid sequence shows significant similarity with corresponding regions in the sugar binding proteins AraS, GlcS, and TreS ofS. solfataricusthat are responsible for anchoring them to the plasma membrane. A strategy based on an effective vector/host genetic system forSulfolobusand on expression control by the promoter of theS. solfataricusgene which encodes the glucose binding protein allowed production of the enzyme in sufficient quantities for study. In fact, the enzyme expressed inS. solfataricuswas stable and highly thermoresistant and showed optimal activity at low pH and high temperature. The protein was detected mainly in the plasma membrane fraction, confirming the structural similarity to the sugar binding proteins. The results of the protein expression in the two different hosts showed that the SSO1354 enzyme is endowed with an endo-β-1-4-glucanase activity and specifically hydrolyzes cellulose. Moreover, it also shows significant but distinguishable specificity toward several other sugar polymers, such as lichenan, xylan, debranched arabinan, pachyman, and curdlan.