bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differential Involvement of the Five RNA Helicases in Adaptation of
Bacillus cereus
ATCC 14579 to Low Growth Temperatures
Authors: Pandiani Franck , Brillard Julien , Bornard Isabelle , Michaud Caroline , Chamot Stéphanie , Nguyen-the Christophe , Broussolle Véronique 
Published: August 2010

ABSTRACT

Bacillus cereus
ATCC 14579 possesses five RNA helicase-encoding genes overexpressed under cold growth conditions. Out of the five corresponding mutants, only the
ΔcshA
,
ΔcshB
, and
ΔcshC
strains were cold sensitive. Growth of the
ΔcshA
strain was also reduced at 30°C but not at 37°C. The cold phenotype was restored with the
cshA
gene for the
ΔcshA
strain and partially for the
ΔcshB
strain but not for the
ΔcshC
strain, suggesting different functions at low temperature.
Genotype and Antibiotic Resistance Analyses of
Campylobacter
Isolates from Ceca and Carcasses of Slaughtered Broiler Flocks
Authors: Wirz Simone E. , Overesch Gudrun , Kuhnert Peter , Korczak Bożena M. 
Published: August 2010

ABSTRACT

To obtain genetic information about
Campylobacter jejuni
and
Campylobacter coli
from broilers and carcasses at slaughterhouses, we analyzed and compared 340 isolates that were collected in 2008 from the cecum right after slaughter or from the neck skin after processing. We performed
rpoB
sequence-based identification, multilocus sequence typing (MLST), and
flaB
sequence-based typing; we additionally analyzed mutations within the 23S rRNA and
gyrA
genes that confer resistance to macrolide and quinolone antibiotics, respectively. The
rpoB
-based identification resulted in a distribution of 72.0%
C. jejuni
and 28.0%
C. coli
. The MLST analysis revealed that there were 59 known sequence types (STs) and 6 newly defined STs. Most of the STs were grouped into 4 clonal complexes (CC) that are typical for poultry (CC21, CC45, CC257, and CC828), and these represented 61.8% of all of the investigated isolates. The analysis of 95 isolates from the cecum and from the corresponding carcass neck skin covered 44 different STs, and 54.7% of the pairs had matching genotypes. The data indicate that cross-contamination from various sources during slaughter may occur, although the majority of
Campylobacter
contamination on carcasses appeared to originate from the slaughtered flock itself. Mutations in the 23S rRNA gene were found in 3.1% of
C. coli
isolates, although no mutations were found in
C. jejuni
isolates. Mutations in the
gyrA
gene were observed in 18.9% of
C. jejuni
and 26.8% of
C. coli
isolates, which included two
C. coli
strains that carried mutations conferring resistance to both classes of antibiotics. A relationship between specific genotypes and antibiotic resistance/susceptibility was observed.
Hydrogen Cycling by the Unicellular Marine Diazotroph
Crocosphaera watsonii
Strain WH8501
Authors: Wilson Samuel T. , Tozzi Sasha , Foster Rachel A. , Ilikchyan Irina , Kolber Zbigniew S. , Zehr Jonathan P. , Karl David M. 
Published: August 2010

ABSTRACT

The hydrogen (H
2
) cycle associated with the dinitrogen (N
2
) fixation process was studied in laboratory cultures of the marine cyanobacterium
Crocosphaera watsonii
. The rates of H
2
production and acetylene (C
2
H
2
) reduction were continuously measured over the diel cycle with simultaneous measurements of fast repetition rate fluorometry and dissolved oxygen. The maximum rate of H
2
production was coincident with the maximum rates of C
2
H
2
reduction. Theoretical stoichiometry for N
2
fixation predicts an equimolar ratio of H
2
produced to N
2
fixed. However, the maximum rate of net H
2
production observed was 0.09 nmol H
2
μg chlorophyll
a
(chl
a
)
−1
h
−1
compared to the N
2
fixation rate of 5.5 nmol N
2
μg chl
a
−1
h
−1
, with an H
2
production/N
2
fixation ratio of 0.02. The 50-fold discrepancy between expected and observed rates of H
2
production was hypothesized to be a result of H
2
reassimilation by uptake hydrogenase. This was confirmed by the addition of carbon monoxide (CO), a potent inhibitor of hydrogenase, which increased net H
2
production rates ∼40-fold to a maximum rate of 3.5 nmol H
2
μg chl
a
−1
h
−1
. We conclude that the reassimilation of H
2
by
C. watsonii
is highly efficient (>98%) and hypothesize that the tight coupling between H
2
production and consumption is a consequence of fixing N
2
at nighttime using a finite pool of respiratory carbon and electrons acquired from daytime solar energy capture. The H
2
cycle provides unique insight into N
2
fixation and associated metabolic processes in
C. watsonii
.
The Transcriptional Regulator Nrg1p Controls Candida albicans Biofilm Formation and Dispersion
Authors: Uppuluri Priya , Pierce Christopher G. , Thomas Derek P. , Bubeck Sarah S. , Saville Stephen P. , Lopez-Ribot Jose L. 
Published: August 2010

ABSTRACT

The ability of
Candida albicans
to reversibly switch morphologies is important for biofilm formation and dispersion. In this pathogen, Nrg1p functions as a key negative regulator of the yeast-to-hypha morphogenetic transition. We have previously described a genetically engineered
C. albicans
tet-NRG1
strain in which
NRG1
expression levels can be manipulated by the presence or absence of doxycycline (DOX). Here, we have used this strain to ascertain the role of Nrg1p in regulating the different stages of the
C. albicans
biofilm developmental cycle. In an
in vitro
model of biofilm formation, the
C. albicans
tet-NRG1
strain was able to form mature biofilms only when DOX was present in the medium, but not in the absence of DOX, when high levels of
NRG1
expression blocked the yeast-to-hypha transition. However, in a biofilm cell retention assay in which biofilms were developed with mixtures of
C. albicans
tet-NRG1
and SC5314 strains,
tet-NRG1
yeast cells were still incorporated into the mixed biofilms, in which an intricate network of hyphae of the wild-type strain provided for biofilm structural integrity and adhesive interactions. Also, utilizing an
in vitro
biofilm model under conditions of flow, we demonstrated that
C. albicans
Nrg1p exerts an exquisite control of the dispersal process, as overexpression of
NRG1
leads to increases in dispersion of yeast cells from the biofilms. Our results demonstrate that manipulation of
NRG1
gene expression has a profound influence on biofilm formation and biofilm dispersal, thus identifying Nrg1p as a key regulator of the
C. albicans
biofilm life cycle.
In Vitro
Analysis of the
Staphylococcus aureus
Lipoteichoic Acid Synthase Enzyme Using Fluorescently Labeled Lipids
Authors: Karatsa-Dodgson Maria , Wörmann Mirka E. , Gründling Angelika 
Published: August 2010

ABSTRACT

Lipoteichoic acid (LTA) is an important cell wall component of Gram-positive bacteria. The key enzyme responsible for polyglycerolphosphate lipoteichoic acid synthesis in the Gram-positive pathogen
Staphylococcus aureus
is the membrane-embedded lipoteichoic acid synthase enzyme, LtaS. It is presumed that LtaS hydrolyzes the glycerolphosphate head group of the membrane lipid phosphatidylglycerol (PG) and catalyzes the formation of the polyglycerolphosphate LTA backbone chain. Here we describe an
in vitro
assay for this new class of enzyme using PG with a fluorescently labeled fatty acid chain (NBD-PG) as the substrate and the recombinant soluble C-terminal enzymatic domain of LtaS (eLtaS). Thin-layer chromatography and mass spectrometry analysis of the lipid reaction products revealed that eLtaS is sufficient to cleave the glycerolphosphate head group from NBD-PG, resulting in the formation of NBD-diacylglycerol. An excess of soluble glycerolphosphate could not compete with the hydrolysis of the fluorescently labeled PG lipid substrate, in contrast to the addition of unlabeled PG. This indicates that the enzyme recognizes and binds other parts of the lipid substrate, besides the glycerolphosphate head group. Furthermore, eLtaS activity was Mn
2+
ion dependent; Mg
2+
and Ca
2+
supported only weak enzyme activity. Addition of Zn
2+
or EDTA inhibited enzyme activity even in the presence of Mn
2+
. The pH optimum of the enzyme was 6.5, characteristic for an enzyme that functions extracellularly. Lastly, we show that the
in vitro
assay can be used to study the enzyme activities of other members of the lipoteichoic acid synthase enzyme family.
Elucidation of β-Oxidation Pathways in
Ralstonia eutropha
H16 by Examination of Global Gene Expression
Authors: Brigham Christopher J. , Budde Charles F. , Holder Jason W. , Zeng Qiandong , Mahan Alison E. , Rha ChoKyun , Sinskey Anthony J. 
Published: August 2010

ABSTRACT

Ralstonia eutropha
H16 is capable of growth and polyhydroxyalkanoate production on plant oils and fatty acids. However, little is known about the triacylglycerol and fatty acid degradation pathways of this bacterium. We compare whole-cell gene expression levels of
R. eutropha
H16 during growth and polyhydroxyalkanoate production on trioleate and fructose. Trioleate is a triacylglycerol that serves as a model for plant oils. Among the genes of note, two potential fatty acid β-oxidation operons and two putative lipase genes were shown to be upregulated in trioleate cultures. The genes of the glyoxylate bypass also exhibit increased expression during growth on trioleate. We observed that single β-oxidation operon deletion mutants of
R. eutropha
could grow using palm oil or crude palm kernel oil as the sole carbon source, regardless of which operon was present in the genome, but a double mutant was unable to grow under these conditions. A lipase deletion mutant did not exhibit a growth defect in emulsified oil cultures but did exhibit a phenotype in cultures containing nonemulsified oil. Mutants of the glyoxylate shunt gene for isocitrate lyase were able to grow in the presence of oils, while a malate synthase (
aceB
) deletion mutant grew more slowly than wild type. Gene expression under polyhydroxyalkanoate storage conditions was also examined. Many findings of this analysis confirm results from previous studies by our group and others. This work represents the first examination of global gene expression involving triacylglycerol and fatty acid catabolism genes in
R. eutropha
.
Comparative Genome Biology of a Serogroup B Carriage and Disease Strain Supports a Polygenic Nature of Meningococcal Virulence
Authors: Joseph Biju , Schneiker-Bekel Susanne , Schramm-Glück Anja , Blom Jochen , Claus Heike , Linke Burkhard , Schwarz Roland F. , Becker Anke , Goesmann Alexander , Frosch Matthias , Schoen Christoph 
Published: August 2010

ABSTRACTNeisseria meningitidisserogroup B strains are responsible for most meningococcal cases in the industrialized countries, and strains belonging to the clonal complex ST-41/44 are among the most prevalent serogroup B strains in carriage and disease. Here, we report the first genome and transcriptome comparison of a serogroup B carriage strain from the clonal complex ST-41/44 to the serogroup B disease strain MC58 from the clonal complex ST-32. Both genomes are highly colinear, with only three major genome rearrangements that are associated with the integration of mobile genetic elements. They further differ in about 10% of their gene content, with the highest variability in gene presence as well as gene sequence found for proteins involved in host cell interactions, including Opc, NadA, TonB-dependent receptors, RTX toxin, and two-partner secretion system proteins. Whereas housekeeping genes coding for metabolic functions were highly conserved, there were considerable differences in their expression pattern upon adhesion to human nasopharyngeal cells between both strains, including differences in energy metabolism and stress response. In line with these genomic and transcriptomic differences, both strains also showed marked differences in theirin vitroinfectivity and in serum resistance. Taken together, these data support the concept of a polygenic nature of meningococcal virulence comprising differences in the repertoire of adhesins as well as in the regulation of metabolic genes and suggest a prominent role for immune selection and genetic drift in shaping the meningococcal genome.
Metabolic Network Analysis of
Pseudomonas aeruginosa
during Chronic Cystic Fibrosis Lung Infection
Authors: Oberhardt Matthew A. , Goldberg Joanna B. , Hogardt Michael , Papin Jason A. 
Published: August 2010

ABSTRACT

System-level modeling is beginning to be used to decipher high throughput data in the context of disease. In this study, we present an integration of expression microarray data with a genome-scale metabolic reconstruction of
P
seudomonas
aeruginosa
in the context of a chronic cystic fibrosis (CF) lung infection. A genome-scale reconstruction of
P. aeruginosa
metabolism was tailored to represent the metabolic states of two clonally related lineages of
P. aeruginosa
isolated from the lungs of a CF patient at different points over a 44-month time course, giving a mechanistic glimpse into how the bacterial metabolism adapts over time in the CF lung. Metabolic capacities were analyzed to determine how tradeoffs between growth and other important cellular processes shift during disease progression. Genes whose knockouts were either significantly growth reducing or lethal
in silico
were also identified for each time point and serve as hypotheses for future drug targeting efforts specific to the stages of disease progression.
Anti-Sinicism: Roots in Pre-industrial Colonial Southern Africa
Authors: Harris Karen L. 
Published: August 2010

AbstractWith the Chinese presence on the African continent being perceived and portrayed as a new global phenomenon there has been a concomitant, albeit sporadic and nuanced, emergence of an aversion to things Chinese, gradually permeating popular consciousness. In a postcolonial world these anti-Sinitic or Sino-phobic sentiments are crudely reminiscent of the late nineteenth century colonial cries of the “yellow peril”, which culminated in acts of exclusion and extreme prohibition that singled out and targeted the Chinese in the various colonies across the Atlantic and Pacific including South Africa. This article, however, proposes to trace the genesis of some of anti-Sinicism to a pre-industrial period by considering developments in colonial Southern Africa. It will show how in the early Dutch settler and British colonial periods at the Cape, when the number of Chinese present in the region was miniscule, negative feelings towards the Chinese as the “other” were already apparent and evident in the reactions to them prior to the arrival of the large numbers which came to America, Australasia and Africa from the mid-nineteenth century onwards.
A Silent Invasion? African Views on the Growing Chinese Presence in Africa: The Case of Equatorial Guinea
Authors: Esteban Mario 
Published: August 2010

AbstractThe literature on African perceptions of the Chinese presence in Africa tends to present two different perspectives on this issue. The works based on opinion polls typically emphasize the positive nature of African views on China, whereas the qualitatively grounded research often point to the presence of both positive and negative perceptions in African discourses on China. Due to the traditional friendship between Beijing and Malabo, the capital of Equatorial Guinea, the Equatoguinean people seemingly have a positive image of China, but the recent fast mounting Chinese presence in the country has started to raise mixed feelings among the bulk of the population. The local political and economic privileged classes who have benefitted most from the growing Chinese presence in Equatorial Guinea tend to be more supportive of this new phenomenon, whereas a minor group of small entrepreneurs and the main opposition parties are firmly critical of China. The present paper intends to shed some light on these contradictory views through a systematic study of the Equatoguinean people’s attitudes towards China and the Chinese, which elucidate three independent variables as the basis of judgment: (1) the nature of the traditional relationship between Africa and China, (2) occupation, and (3) political affiliation.
Chinese Migrants and Society in Mali: Local Constructions of Globalization
Authors: Bourdarias Françoise 
Published: August 2010

AbstractIn this contribution, I shall consider the social perceptions of politics and economy related to the interdependences between Chinese migrants and local population in Mali. Such representations give a particular shape to a large number of identity constructions. In each specific context, the spaces and groups to which Malian and Chinese residents refer, highlight social representations of the two nation-states and societies, of their present relationships. Individual and collective strategies should then be analysed from a point of view stressing the links between economic rationalities and political constructions.
Chinese Farms in Zambia: From Socialist to “Agro-Imperialist” Engagement?
Authors: Hairong Yan , Sautman Barry 
Published: August 2010

AbstractParticipation by Chinese in Zambia’s agriculture has involved three modes of engagement. Two of these, agro-socialist cooperation until the late 1980s and agro-capitalist “win-win,” since the 1990s, can be examined. The third one, an “agro-imperialist” mode, is not an experience, but a speculation, one possible future based on the Chinese state’s potential to allow firms from China to join in the large-scale, export-oriented “land grabs” by big transnational firms that have occurred since food crises in the developing world in the late 2000s. This paper analyzes all three modes of Chinese engagement, but necessarily concentrates on the second, present-day mode, agro-capitalism. We argue that the present Chinese engagement with Zambian agriculture makes small-scale positive contributions to the domestic food market in Zambia. At the same time, its agro-capitalist production involves the exploitation of farm workers that is typically at the core of commercial farming regardless of the national origins of farm owners. We also contend that while Chinese in Zambia and Africa are not carrying out agro-imperialism, they will likely do so if Chinese leaders decide that this practice represents an international standard.
Strife for Independence in an Autocratic Regime: The Egyptian Judges' Club 2000-2007
Authors: Bentlage Björn 
Published: August 2010

AbstractThis article describes and examines a conflict between the Egyptian Judges' Club and the regime in the years 2000-2007. Due to the Club's special status, this conflict illustrates several developments in today's Egypt: It relates to the state of the judiciary, professional syndicates, national elections and overall state politics. The judges' strife for independence serves as an example of the ways and means of representation, contestation and control in an authoritarian regime.
Nijhoff in America: Booksellers from the Netherlands and the Development of American Research Libraries – Part I
Authors: Edelman Hendrik 
Published: August 2010

AbstractAmerican libraries began to be developed in the middle of the nineteenth century and were among the world's most prominent a century later. The remarkable history of the major libraries in North America, their European models and their strong and innovative leadership is reported here in more or less chronological sequence from the earliest efforts to about 1970, when the unprecedented growth came to an end. The building of the international library collections could not have been achieved without the enterprising efforts of many booksellers in England and on the European continent. Among those who made significant contributions, were three booksellers from the Netherlands: Frederik Muller, Martinus Nijhoff and Swets & Zeitlinger. This article describes their role, but concentrates on Martinus Nijhoff, publisher and bookseller of The Hague, who had by far the longest successful tenure in supplying American libraries with European books and periodicals. Between 1853 and 1971, three generations of the Nijhoff family – Martinus, Wouter and Wouter Pzn –, with their staff members, built one of the leading international publishing and bookselling houses in the Netherlands. Their legacy is permanently embedded in the collections of the great North American libraries.
Maternal investment in egg production: environmental and population-specific effects on offspring performance in the snapping shrimp Alpheus nuttingi (Schmitt, 1924) (Decapoda, Alpheidae)
Authors: Pavanelli Caio , Mossolin Emerson , Mantelatto Fernando 
Published: August 2010

Abstract
Among marine invertebrates, the overall biomass invested in egg production varies widely within populations, which can result from the interaction of endogenous and exogenous factors. Species that have constant reproduction throughout the year can be good models to study the influence of environmental factors on reproductive processes. We conducted a seasonal comparison of egg production in the intertidal snapping shrimp Alpheus nuttingi, which shows a continuous reproductive pattern, to examine the hypothesis that differences in egg production are driven by environmental conditions and population features. This population showed an uncommon strategy, characterized by females that produce eggs of varying sizes within their clutches, with reduced egg volume when the number of eggs is higher (Spring-Summer). In these seasons, higher temperatures and greater food availability may allow the production of more eggs compared to the Autumn-Winter seasons. Compared to other alpheid shrimps, this population produces small eggs, but in larger numbers. Despite the higher fecundity, the reproductive output is relatively low, this production being supported by the large size of females from the southern Atlantic region. Our findings showed that the egg production of A. nuttingi was greatly influenced by environmental factors. Therefore, this shrimp, and probably other decapods that possess continuous reproduction, adopt different reproductive strategies during the year.
Oocyte and ovary morphological observation of gray wolf (Canis lupus)
Authors: Li Feng-Yin , Tao Yong , Fang Fu-Gui , Li Yun-Sheng , Zhang Yun-Hai , Zhang Zhi-Zhong , Liu Xu-Guang 
Published: August 2010

Abstract
The present study was carried out to describe the reproductive system of a single adult female wolf, including the uterine horns, cervix, ovaries and follicles. The cumulus oocytes complexes (COCs) and oocytes were also examined. The results showed that the size of each ovary was about 9 × 6 mm with an average of weight of 461.3 mg. The uterus was Y-shaped, and the length of each uterine horn was 14 cm. The distance from the cervix to the bifurcation of the uterine horns was also 14 cm. The left ovary had two large follicles on the surface with a diameter more than 4 mm, while the right ovary had no protuberant follicles. The ovaries were covered with a lot of fat, and were well developed. The COCs derived from the antral follicles were dark, and the nuded oocytes had a dark cytoplasm. The diameter of the oocytes removed from the antral follicles was 116.8 μm on average. The ovaries had a smooth surface and all the follicles were under the surface except for two big follicles on the left ovary. Histological examination of the ovaries by haematoxylin and eosin staining demonstrated that the primordial, primary, preantral and antral follicles were scattered in the cortex, the medulla was abundant with blood vessels. This study preliminarily reveals the features of the wolf reproductive system and the structure of its oocytes and ovaries, which might be indicative for further study and the protection of the species.