bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of soluble glass bolus administration on the blood selenium concentration in grazing Philippine goats under backyard conditions
Authors: HAYASHIDA Maki , ORDEN Edgar A. , CRUZ Emilio M. , CRUZ Libertado C. , FUJIHARA Tsutomu 
Published: December 2006

ABSTRACTThe present study was conducted to determine the effects of selenium (Se) soluble glass bolus (SGB) on blood Se concentrations of mixed‐bred (native × Anglo Nubian) pregnant does weighing between 15 and 52 kg and grazing on natural pastures in the Philippines. The control group, consisting of 28 does, was not administered with SGB, while 23 does were administered with SGB every 6 months for a period of 12 months. Forage and blood samples in both groups were collected every 2 months. Their Se, sulfur, calcium, phosphorus, magnesium, copper and zinc concentrations were analyzed using the wet digestion method. The results showed that the grazed forage had concentrations of all these minerals that were far higher than the accepted critical lower levels. The Se concentration was higher (P < 0.05) in the dry season than in the rainy season, especially in the whole blood collected from the does and newborn kids. In both groups the Se concentration in the kids tended to increase during the suckling period but decreased after weaning. Kids born to the SGB does had higher whole blood Se concentrations (P < 0.05) than those born to the control does. However, the administration of SGB to the does did not affect any blood mineral concentrations except for Se in the grazing does and their kids. The animals did not exhibit any clinical signs of mineral deficiencies or toxicities during the experimental period.
Effect of recombinant bovine tumor necrosis factor‐α on hormone release in lactating cows
Authors: KUSHIBIKI Shiro , SHINGU Hiroyuki , KOMATSU Tokushi , ITOH Fumiaki , KASUYA Etsuko , ASO Hisashi , HODATE Koichi 
Published: December 2006

ABSTRACTTumor necrosis factor (TNF)‐α is a powerful macrophage cytokine released during infection, circulating in the blood to produce diverse effects in the organism. We examined the effect of recombinant bovine TNF‐α (rbTNF‐α) administration on hormone release in dairy cows during early lactation. Twelve non‐pregnant Holstein cows were treated subcutaneously with rbTNF‐α (2.5 µg/kg) or saline twice (at 11.00 and 23.00 hours). At 11.00 hours the next day, the cows were given growth hormone‐releasing hormone (GHRH, 0.25 µg/kg), thyrotrophin‐releasing hormone (TRH, 1.0 µg/kg), thyroid‐stimulating hormone (TSH, 10 µg/kg) or adrenocorticotropic hormone (500 µg/head) via the jugular vein. In the growth hormone‐releasing hormone challenge, the plasma growth hormone concentration was lower in the rbTNF‐α group than in the control (saline) group. The growth hormone and TSH responses to TRH were also smaller in the rbTNF‐α group than in the control. The plasma prolactin response to TRH was not affected by the rbTNF‐α treatment. In the TSH challenge, the rbTNF‐α‐treated cows had lower responses, as measured by plasma triiodothyronine and thyroxine, than the control cows. The rbTNF‐α treatment produced an increase in the basal plasma cortisol level, but the cortisol response to adrenocorticotropic hormone was the same level in both groups. The plasma concentrations of TNF‐α and interleukin‐1β in the cows were elevated by the rbTNF‐α treatment. The milk yield was reduced by the rbTNF‐α administration during 4 days. These data demonstrate that TNF‐α alters the secretion of pituitary and thyroid hormones in lactating cows. This effect may contribute to the suppression of the lactogenic function of the mammary gland observed in cases of coliform mastitis with high circulating TNF‐α levels.
Cre-
lox
-Based System for Multiple Gene Deletions and Selectable-Marker Removal in
Lactobacillus plantarum
Authors: Lambert Jolanda M. , Bongers Roger S. , Kleerebezem Michiel 
Published: December 2006

ABSTRACT

The classic strategy to achieve gene deletion variants is based on double-crossover integration of nonreplicating vectors into the genome. In addition, recombination systems such as Cre-
lox
have been used extensively, mainly for eukaryotic organisms. This study presents the construction of a Cre-
lox
-based system for multiple gene deletions in
Lactobacillus plantarum
that could be adapted for use on gram-positive bacteria. First, an effective mutagenesis vector (pNZ5319) was constructed that allows direct cloning of blunt-end PCR products representing homologous recombination target regions. Using this mutagenesis vector, double-crossover gene replacement mutants could be readily selected based on their antibiotic resistance phenotype. In the resulting mutants, the target gene is replaced by a
lox66
-P
32
-
cat-lox71
cassette, where
lox66
and
lox71
are mutant variants of
loxP
and P
32
-
cat
is a chloramphenicol resistance cassette. The
lox
sites serve as recognition sites for the Cre enzyme, a protein that belongs to the integrase family of site-specific recombinases. Thus, transient Cre recombinase expression in double-crossover mutants leads to recombination of the
lox66
-P
32
-
cat-lox71
cassette into a double-mutant
loxP
site, called
lox72
, which displays strongly reduced recognition by Cre. The effectiveness of the Cre-
lox
-based strategy for multiple gene deletions was demonstrated by construction of both single and double gene deletions at the
melA
and
bsh1
loci on the chromosome of the gram-positive model organism
Lactobacillus plantarum
WCFS1. Furthermore, the efficiency of the Cre-
lox
-based system in multiple gene replacements was determined by successive mutagenesis of the genetically closely linked loci
melA
and
lacS2
in
L. plantarum
WCFS1. The fact that 99.4% of the clones that were analyzed had undergone correct Cre-
lox
resolution emphasizes the suitability of the system described here for multiple gene replacement and deletion strategies in a single genetic background.
Physiological, Ecological, and Phylogenetic Characterization of
Stappia
, a Marine CO-Oxidizing Bacterial Genus
Authors: Weber Carolyn F. , King Gary M. 
Published: December 2006

ABSTRACT

Bacteria play a major role in marine CO cycling, yet very little is known about the microbes involved. Thirteen CO-oxidizing
Stappia
isolates obtained from existing cultures, macroalgae, or surf samples representing geographically and ecologically diverse habitats were characterized using biochemical, physiological, and phylogenetic approaches. All isolates were aerobic chemoorganotrophs that oxidized CO at elevated (1,000 ppm) and ambient-to-subambient concentrations (<0.3 ppm). All contained the form I (OMP)
coxL
gene for aerobic CO dehydrogenase and also the form II (BMS) putative
coxL
gene. In addition, some strains possessed
cbbL
, the large subunit gene for ribulose-1,5-bisphosphate carboxylase/oxygenase, suggesting the possibility of lithotrophic or mixotrophic metabolism. All isolates used a wide range of sugars, organic acids, amino acids, and aromatics for growth and grew at salinities from 5 to 45 ppt. All but one isolate denitrified or respired nitrate. Phylogenetic analyses based on 16S rRNA gene sequences indicated that several isolates could not be distinguished from
Stappia aggregata
and contributed to a widely distributed species complex. Four isolates (of strains GA15, HI, MIO, and M4) were phylogenetically distinct from validly described
Stappia
species and closely related genera (e.g.,
Ahrensia
,
Pannonibacter
,
Pseudovibrio
, and
Roseibium
). Substrate utilization profiles, enzymatic activity, and membrane lipid composition further distinguished these isolates and supported their designations as new
Stappia
species. The observed metabolic versatility of
Stappia
likely accounts for its cosmopolitan distribution and its ability to contribute to CO cycling as well as other important biogeochemical cycles.
Induction by Hypoxia of Heterologous-Protein Production with the Kl
PDC1
Promoter in Yeasts
Authors: Camattari Andrea , Bianchi Michele M. , Branduardi Paola , Porro Danilo , Brambilla Luca 
Published: December 2006

ABSTRACT

The control of promoter activity by oxygen availability appears to be an intriguing system for heterologous protein production. In fact, during cell growth in a bioreactor, an oxygen shortage is easily obtained simply by interrupting the air supply. The purpose of our work was to explore the possible use of hypoxic induction of the Kl
PDC1
promoter to direct heterologous gene expression in yeast. In the present study, an expression system based on the Kl
PDC1
promoter was developed and characterized. Several heterologous proteins, differing in size, origin, localization, and posttranslational modification, were successfully expressed in
Kluyveromyces lactis
under the control of the wild type or a modified promoter sequence, with a production ratio between 4 and more than 100. Yields were further optimized by a more accurate control of hypoxic physiological conditions. Production of as high as 180 mg/liter of human interleukin-1β was obtained, representing the highest value obtained with yeasts in a lab-scale bioreactor to date. Moreover, the transferability of our system to related yeasts was assessed. The
l
ac
Z
gene from
Escherichia coli
was cloned downstream of the Kl
PDC1
promoter in order to get β-galactosidase activity in response to induction of the promoter. A centromeric vector harboring this expression cassette was introduced in
Saccharomyces cerevisiae
and in
Zygosaccharomyces bailii
, and effects of hypoxic induction were measured and compared to those already observed in
K. lactis
cells. Interestingly, we found that the induction still worked in
Z. bailii
; thus, this promotor constitutes a possible inducible system for this new nonconventional host.
The Presence of N-Terminal Secretion Signal Sequences Leads to Strong Stimulation of the Total Expression Levels of Three Tested Medically Important Proteins during High-Cell-Density Cultivations of
Escherichia coli
Authors: Sletta H. , Tøndervik A. , Hakvåg S. , Aune T. E. Vee , Nedal A. , Aune R. , Evensen G. , Valla S. , Ellingsen T. E. , Brautaset T. 
Published: December 2006

ABSTRACT

Genetic optimizations to achieve high-level production of three different proteins of medical importance for humans, granulocyte-macrophage colony-stimulating factor (GM-CSF), interferon alpha 2b (IFN-α2b), and single-chain antibody variable fragment (scFv-phOx), were investigated during high-cell-density cultivations of
Escherichia coli
. All three proteins were poorly expressed when put under control of the strong
Pm/xylS
promoter/regulator system, but high volumetric yields of GM-CSF and scFv-phOx (up to 1.7 and 2.3 g/liter, respectively) were achieved when the respective genes were fused to a translocation signal sequence. The choice of signal sequence,
pelB
,
ompA
, or synthetic signal sequence CSP, displayed a high and specific impact on the total expression levels for these two proteins. Data obtained by quantitative PCR confirmed relatively high in vivo transcript levels without using a fused signal sequence, suggesting that the signal sequences mainly stimulate translation. IFN-α2b expression remained poor even when fused to a signal sequence, and an alternative IFN-α2b coding sequence that was optimized for effective expression in
Escherichia coli
was therefore synthesized. The total expression level of this optimized gene remained low, while high-level production (0.6 g/liter) was achieved when the gene was fused to a signal sequence. Together, our results demonstrate a critical role of signal sequences for achieving industrial level expression of three human proteins in
E. coli
under the conditions tested, and this effect has to our knowledge not previously been systematically investigated.
Role of Cytochrome
bd
Oxidase from
Corynebacterium glutamicum
in Growth and Lysine Production
Authors: Kabus Armin , Niebisch Axel , Bott Michael 
Published: December 2006

ABSTRACT

Corynebacterium glutamicum
possesses two terminal oxidases, cytochrome
aa
3
and cytochrome
bd
. Cytochrome
aa
3
forms a supercomplex with the cytochrome
bc
1
complex, which contains an unusual diheme cytochrome
c
1
. Both the
bc
1
-
aa
3
supercomplex and cytochrome
bd
transfer reducing equivalents from menaquinol to oxygen; however, they differ in their proton translocation efficiency by a factor of three. Here, we analyzed the role of cytochrome
bd
for growth and lysine production. When cultivated in glucose minimal medium, a
cydAB
deletion mutant of
C. glutamicum
ATCC 13032 grew like the wild type in the exponential phase, but growth thereafter was inhibited, leading to a biomass formation 40% less than that of the wild type. Constitutive overproduction of functional cytochrome
bd
oxidase in ATCC 13032 led to a reduction of the growth rate by ∼45% and of the maximal biomass by ∼35%, presumably as a consequence of increased electron flow through the inefficient cytochrome
bd
oxidase. In the
l
-lysine-producing
C. glutamicum
strain MH20-22B, deletion of the
cydAB
genes had only minor effects on growth rate and biomass formation, but lysine production was increased by ∼12%. Thus, the respiratory chain was shown to be a target for improving amino acid production by
C. glutamicum
.
Induction of a Global Stress Response during the First Step of
Escherichia coli
Plate Growth
Authors: Cuny Caroline , Lesbats Maïalène , Dukan Sam 
Published: December 2006

ABSTRACT

We have investigated the first events that occur when exponentially grown cells are transferred from a liquid medium (Luria-Bertani [LB]) to a solid medium (LB agar [LBA]). We observed an initial lag phase of 180 min for the wild type MG1655 without any apparent growth. This lack of growth was independent of the bacterial physiological state (either the stationary or the exponential phase), the solid medium composition, or the number of cells on the plate, but it was dependent on the bacterial genotype. Using
lacZ
-reporter fusions and two-dimensional electrophoresis analysis, we observed that when cells from exponential-phase cultures were plated on LBA, several global regulons, like heat shock regulons (RpoH, RpoE, CpxAR) and oxidative-stress regulons (SoxRS, OxyR, Fur), were immediately induced. Our results indicate that in order to grow on plates, bacteria must not only adapt to new conditions but also perceive a real stress.
Coupling ofMethanothermobacter thermautotrophicusMethane Formation and Growth in Fed-Batch and Continuous Cultures under Different H2Gassing Regimens
Authors: de Poorter Linda M. I. , Geerts Wim J. , Keltjens Jan T. 
Published: December 2006

ABSTRACTIn nature, H2- and CO2-utilizing methanogenic archaea have to couple the processes of methanogenesis and autotrophic growth under highly variable conditions with respect to the supply and concentration of their energy source, hydrogen. To study the hydrogen-dependent coupling between methanogenesis and growth,Methanothermobacter thermautotrophicuswas cultured in a fed-batch fermentor and in a chemostat under different 80% H2-20% CO2gassing regimens while we continuously monitored the dissolved hydrogen partial pressures (pH2). In the fed-batch system, in which the conditions continuously changed the uptake rates by the growing biomass, the organism displayed a complex and yet defined growth behavior, comprising the consecutive lag, exponential, and linear growth phases. It was found that the in situ hydrogen concentration affected the coupling between methanogenesis and growth in at least two respects. (i) The microorganism could adopt two distinct theoretical maximal growth yields (YCH4max), notably approximately 3 and 7 g (dry weight) of methane formed mol−1, for growth under low (pH2< 12 kPa)- and high-hydrogen conditions, respectively. The distinct values can be understood from a theoretical analysis of the process of methanogenesis presented in the supplemental material associated with this study. (ii) The in situ hydrogen concentration affected the “specific maintenance” requirements or, more likely, the degree of proton leakage and proton slippage processes. At lowpH2values, the “specific maintenance” diminished and the specific growth yields approachedYCH4max, indicating that growth and methanogenesis became fully coupled.
Characterization of a Large, Stable, High-Copy-Number
Streptomyces
Plasmid That Requires Stability and Transfer Functions for Heterologous Polyketide Overproduction
Authors: Fong Ryan , Hu Zhihao , Hutchinson C. Richard , Huang Jianqiang , Cohen Stanley , Kao Camilla 
Published: December 2006

ABSTRACT

A major limitation to improving small-molecule pharmaceutical production in streptomycetes is the inability of high-copy-number plasmids to tolerate large biosynthetic gene cluster inserts. A recent finding has overcome this barrier. In 2003, Hu et al. discovered a stable, high-copy-number, 81-kb plasmid that significantly elevated production of the polyketide precursor to the antibiotic erythromycin in a heterologous
Streptomyces
host (J. Ind. Microbiol. Biotechnol. 30:516-522, 2003). Here, we have identified mechanisms by which this SCP2*-derived plasmid achieves increased levels of metabolite production and examined how the 45-bp deletion mutation in the plasmid replication origin increased plasmid copy number. A plasmid intramycelial transfer gene,
spd
, and a partition gene,
parAB
, enhance metabolite production by increasing the stable inheritance of large plasmids containing biosynthetic genes. Additionally, high product titers required both activator (
actII-ORF4
) and biosynthetic genes (
eryA
) at high copy numbers. DNA gel shift experiments revealed that the 45-bp deletion abolished replication protein (RepI) binding to a plasmid site which, in part, supports an iteron model for plasmid replication and copy number control. Using the new information, we constructed a large high-copy-number plasmid capable of overproducing the polyketide 6-deoxyerythronolide B. However, this plasmid was unstable over multiple culture generations, suggesting that other SCP2* genes may be required for long-term, stable plasmid inheritance.
Recovery of
Mycobacterium bovis
from Soft Fresh Cheese Originating in Mexico
Authors: Harris N. Beth , Payeur Janet , Bravo Doris , Osorio Ruben , Stuber Tod , Farrell David , Paulson Debra , Treviso Scarlett , Mikolon Andrea , Rodriguez-Lainz Alfonso , Cernek-Hoskins Shannon , Rast Robert , Ginsberg Michele , Kinde Hailu 
Published: December 2006

ABSTRACT

Recent outbreaks of human tuberculosis in the United States caused by
Mycobacterium bovis
have implicated cheese originating in Mexico as a source of these infections. A total of 203 samples of cheese originating in Mexico were cultured, and
M. bovis
was recovered from one specimen. Therefore,
M. bovis
can be recovered from cheese and may be a source of human infections.
Differentiation of
Listeria monocytogenes
Serovars by Using Artificial Neural Network Analysis of Fourier-Transformed Infrared Spectra
Authors: Rebuffo-Scheer Cecilia A. , Schmitt Jürgen , Scherer Siegfried 
Published: December 2006

ABSTRACT

A classification system based on Fourier transform infrared (FTIR) spectroscopy combined with artificial neural network analysis was designed to differentiate 12 serovars of
Listeria monocytogenes
using a reference database of 106 well-defined strains. External validation was performed using a test set of another 166
L. monocytogenes
strains. The O antigens (serogroup) of 164 strains (98.8%) could be identified correctly, and H antigens were correctly determined in 152 (91.6%) of the test strains. Importantly, 40 out of 41 potentially epidemic serovar 4b strains were unambiguously identified. FTIR analysis is superior to PCR-based systems for serovar differentiation and has potential for the rapid, simultaneous identification of both species and serovar of an unknown
Listeria
isolate by simply measuring a whole-cell infrared spectrum.
Isolation of
Rickettsia rhipicephali
and
Rickettsia bellii
from
Haemaphysalis juxtakochi
Ticks in the State of São Paulo, Brazil
Authors: Labruna Marcelo B. , Pacheco Richard C. , Richtzenhain Leonardo J. , Szabó Matias P. J. 
Published: December 2006

ABSTRACT

In the present study, attempts to isolate
Rickettsia
in cell culture were performed individually in seven specimens of
Haemaphysalis juxtakochi
ticks collected in the state of São Paulo (southeastern Brazil).
Rickettsia
was successfully isolated by the shell vial technique and established in Vero cell culture from six ticks (six isolates). DNA extracted from infected cells of these isolates was tested by PCR and DNA sequencing, using genus-specific
Rickettsia
primers targeting the genes
gltA
,
htrA
,
ompA
, and
ompB
. After the generated sequences were compared with available sequences in GenBank, five out of the six isolates were identified as
Rickettsia bellii
(isolates HJ#1, HJ#2, HJ#3, HJ#4, and HJ#7). The sixth isolate (HJ#5) was closest to
Rickettsia
sp. strain R300, previously detected in
H. juxtakochi
in northern Brazil, and to
Rickettsia rhipicephali
, isolated from ticks in the United States. Following recent gene sequence-based criteria proposed for the identification of
Rickettsia
isolates, both isolate HJ#5 and strain R300 were identified as South American strains of
R. rhipicephali
, which was confirmed in this continent for the first time. Isolation of
R. bellii
from
H. juxtakochi
ticks, added to eight other tick species that have been reported to be infected with this bacterium in Brazil, indicates that
R. bellii
is indeed the most frequent
Rickettsia
species infecting ticks in Brazil. Currently, the role of both
R. rhipicephali
and
R. bellii
as human pathogens is regarded as unknown.
A Two-Component System Regulates the Expression of an ABC Transporter for Xylo-Oligosaccharides inGeobacillus stearothermophilus
Authors: Shulami Smadar , Zaide Galia , Zolotnitsky Gennady , Langut Yael , Feld Geoff , Sonenshein Abraham L. , Shoham Yuval 
Published: December 2006

ABSTRACTGeobacillus stearothermophilusT-6 utilizes an extensive and highly regulated hemicellulolytic system. The genes comprising the xylanolytic system are clustered in a 39.7-kb chromosomal segment. This segment contains a 6-kb transcriptional unit (xynDCEFG) coding for a potential two-component system (xynDC) and an ATP-binding cassette (ABC) transport system (xynEFG). ThexynDpromoter region contains a 16-bp inverted repeat resembling the operator site for the xylose repressor, XylR. XylR was found to bind specifically to this sequence, and binding was efficiently prevented in vitro in the presence of xylose. The ABC transport system was shown to comprise an operon of three genes (xynEFG) that is transcribed from its own promoter. The nonphosphorylated fused response regulator, His6-XynC, bound to a 220-bp fragment corresponding to thexynEoperator. DNase I footprinting analysis showed four protected zones that cover the −53 and the +34 regions and revealed direct repeat sequences of a GAAA-like motif. In vitro transcriptional assays and quantitative reverse transcription-PCR demonstrated thatxynEtranscription is activated 140-fold in the presence of 1.5 μM XynC. The His6-tagged sugar-binding lipoprotein (XynE) of the ABC transporter interacted with different xylosaccharides, as demonstrated by isothermal titration calorimetry. The change in the heat capacity of binding (ΔCp) for XynE with xylotriose suggests a stacking interaction in the binding site that can be provided by a single Trp residue and a sugar moiety. Taken together, our data show that XynEFG constitutes an ABC transport system for xylo-oligosaccharides and that its transcription is negatively regulated by XylR and activated by the response regulator XynC, which is part of a two-component sensing system.