bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enhanced UV Inactivation of Adenoviruses under Polychromatic UV Lamps
Authors: Linden Karl G. , Thurston Jeanette , Schaefer Raymond , Malley James P. 
Published: October 2007

ABSTRACT

Adenovirus is recognized as the most UV-resistant waterborne pathogen of concern to public health microbiologists. The U.S. EPA has stipulated that a UV fluence (dose) of 186 mJ cm
−2
is required for 4-log inactivation credit in water treatment. However, all adenovirus inactivation data to date published in the peer-reviewed literature have been based on UV disinfection experiments using UV irradiation at 253.7 nm produced from a conventional low-pressure UV source. The work reported here presents inactivation data for adenovirus based on polychromatic UV sources and details the significant enhancement in inactivation achieved using these polychromatic sources. When full-spectrum, medium-pressure UV lamps were used, 4-log inactivation of adenovirus type 40 is achieved at a UV fluence of less than 60 mJ cm
−2
and a surface discharge pulsed UV source required a UV fluence of less than 40 mJ cm
−2
. The action spectrum for adenovirus type 2 was also developed and partially explains the improved inactivation based on enhancements at wavelengths below 230 nm. Implications for water treatment, public health, and the future of UV regulations for virus disinfection are discussed.
Hydrogen Peroxide-Dependent Uptake of Iodine by Marine
Flavobacteriaceae
Bacterium Strain C-21
Authors: Amachi Seigo , Kimura Koh , Muramatsu Yasuyuki , Shinoyama Hirofumi , Fujii Takaaki 
Published: October 2007

ABSTRACT

The cells of the marine bacterium strain C-21, which is phylogenetically closely related to
Arenibacter troitsensis
, accumulate iodine in the presence of glucose and iodide (I
−
). In this study, the detailed mechanism of iodine uptake by C-21 was determined using a radioactive iodide tracer,
125
I
−
. In addition to glucose, oxygen and calcium ions were also required for the uptake of iodine. The uptake was not inhibited or was only partially inhibited by various metabolic inhibitors, whereas reducing agents and catalase strongly inhibited the uptake. When exogenous glucose oxidase was added to the cell suspension, enhanced uptake of iodine was observed. The uptake occurred even in the absence of glucose and oxygen if hydrogen peroxide was added to the cell suspension. Significant activity of glucose oxidase was found in the crude extracts of C-21, and it was located mainly in the membrane fraction. These findings indicate that hydrogen peroxide produced by glucose oxidase plays a key role in the uptake of iodine. Furthermore, enzymatic oxidation of iodide strongly stimulated iodine uptake in the absence of glucose. Based on these results, the mechanism was considered to consist of oxidation of iodide to hypoiodous acid by hydrogen peroxide, followed by passive translocation of this uncharged iodine species across the cell membrane. Interestingly, such a mechanism of iodine uptake is similar to that observed in iodine-accumulating marine algae.
Identification of a Chlorobenzene Reductive Dehalogenase in
Dehalococcoides
sp. Strain CBDB1
Authors: Adrian Lorenz , Rahnenführer Jan , Gobom Johan , Hölscher Tina 
Published: October 2007

ABSTRACT

A chlorobenzene reductive dehalogenase of the anaerobic dehalorespiring bacterium
Dehalococcoides
sp. strain CBDB1 was identified. Due to poor biomass yields, standard protein isolation procedures were not applicable. Therefore, cell extracts from cultures grown on trichlorobenzenes were separated by native polyacrylamide gel electrophoresis and analyzed directly for chlorobenzene reductive dehalogenase activity within gel fragments. Activity was found in a single band, even though electrophoretic separation was performed under aerobic conditions. Matrix-assisted laser desorption ionization mass spectrometry (MALDI MS) and nano-liquid chromatography-MALDI MS analysis of silver-stained replicas of the active band on native polyacrylamide gels identified a protein product of the cbdbA84 gene, now called
cbrA
. The cbdbA84 gene is one of 32 reductive dehalogenase homologous genes present in the genome of strain CBDB1. The chlorobenzene reductive dehalogenase identified in our study represents a member of the family of corrinoid/iron-sulfur cluster-containing reductive dehalogenases. No orthologs of cbdbA84 were found in the completely sequenced genomes of
Dehalococcoides
sp. strains 195 and BAV1 nor among the genes amplified from
Dehalococcoides
sp. strain FL2 or mixed cultures containing
Dehalococcoides
. Another dehalogenase homologue (cbdbA80) was expressed in cultures that contained 1,2,4-trichlorobenzene, but its role is unclear. Other highly expressed proteins identified with our approach included the major subunit of a protein annotated as formate dehydrogenase, transporter subunits, and a putative S-layer protein.
Frequency of Secondary Symbiont Infection in an Invasive Psyllid Relates to Parasitism Pressure on a Geographic Scale in California
Authors: Hansen A. K. , Jeong G. , Paine T. D. , Stouthamer R. 
Published: October 2007

ABSTRACT

Two endosymbionts, an obligate primary symbiont and a facultative secondary symbiont, are harbored within the invasive red gum (eucalyptus) lerp psyllid,
Glycaspis brimblecombei
, in California. An extensive survey of diversity and frequency of
G. brimblecombei
's secondary symbiont in multiple populations throughout the state of California was conducted using PCR detection, restriction enzymes, cloning, and sequencing. A total of 380
G. brimblecombei
individuals in 19 populations were screened for secondary symbionts. Based on molecular screening results, only one type of secondary symbiont was present in
G. brimblecombei
populations in California. Overall, 40% of the 380 psyllids screened were infected with the secondary symbiont. Interestingly, secondary symbiont infection frequencies in
G. brimblecombei
populations varied dramatically from 0 to 75% and were significantly related to parasitism pressure by
Psyllaphaegus bliteus
, a solitary endoparasitoid of the psyllid.
Genetic and Immunological Comparison of the Cladoceran Parasite
Pasteuria ramosa
with the Nematode Parasite
Pasteuria penetrans
Authors: Schmidt Liesbeth M. , Mouton Laurence , Nong Guang , Ebert Dieter , Preston James F. 
Published: October 2007

ABSTRACT

Pasteuria penetrans
, an obligate endospore-forming parasite of
Meloidogyne
spp. (root knot nematodes), has been identified as a promising agent for biocontrol of these destructive agricultural crop pests.
Pasteuria ramosa
, an obligate parasite of water fleas (
Daphnia
spp.), has been shown to modulate cladoceran populations in natural ecosystems. Selected sporulation genes and an epitope associated with the spore envelope of these related species were compared. The
sigE
and
spoIIAA
/
spoIIAB
genes differentiate the two species to a greater extent than 16S rRNA and may serve as probes to differentiate the species. Single-nucleotide variations were observed in several conserved genes of five distinct populations of
P. ramosa
, and while most of these variations are silent single-nucleotide polymorphisms, a few result in conservative amino acid substitutions. A monoclonal antibody directed against an adhesin epitope present on
P. penetrans
P20 endospores, previously determined to be specific for
Pasteuria
spp. associated with several phytopathogenic nematodes, also detects an epitope associated with
P. ramosa
endospores. Immunoblotting provided patterns that differentiate
P. ramosa
from other
Pasteuria
spp. This monoclonal antibody thus provides a probe with which to detect and discriminate endospores of different
Pasteuria
spp. The presence of a shared adhesin epitope in two species with such ecologically distant hosts suggests that there is an ancient and ecologically significant recognition process in these endospore-forming bacilli that contributes to the virulence of both species in their respective hosts.
Ubericin A, a Class IIa Bacteriocin Produced by
Streptococcus uberis
Authors: Heng Nicholas C. K. , Burtenshaw Grace A. , Jack Ralph W. , Tagg John R. 
Published: October 2007

ABSTRACT

Streptococcus uberis
, a causal agent of bovine mastitis, produces ubericin A, a 5.3-kDa class IIa (pediocin-like) bacteriocin, which was purified and characterized. The
uba
locus comprises two overlapping genes:
ubaA
(ubericin A precursor peptide) and
ubaI
(putative immunity protein). Ubericin A is the first streptococcal class IIa bacteriocin to be characterized.
Expression of
Mycoplasma
Proteins Carrying an Affinity Tag in
M. pneumoniae
Allows Rapid Purification and Circumvents Problems Related to the Aberrant Genetic Code
Authors: Schmidl Sebastian R. , Hames Claudine , Stülke Jörg 
Published: October 2007

ABSTRACT

In
Mycoplasma pneumoniae
and several other mollicutes, the UGA opal codon specifies tryptophan rather than a translation stop. This often makes it difficult to express
Mycoplasma
proteins in heterologous hosts. In this work, we demonstrate that mollicute proteins can be fused to an affinity tag and be expressed directly in
M. pneumoniae
. The protein can then be purified by affinity chromatography and be used for biochemical or any other desired analysis.
Identification of a Malate Chemoreceptor in
Pseudomonas aeruginosa
by Screening for Chemotaxis Defects in an Energy Taxis-Deficient Mutant
Authors: Alvarez-Ortega Carolina , Harwood Caroline S. 
Published: October 2007

ABSTRACT

We found that a robust energy taxis response mediated by the Aer receptor can sometimes mask chemotaxis mediated by other methyl-accepting chemotaxis proteins (MCPs) in
Pseudomonas aeruginosa
. We identified PA2652 as a chemoreceptor for malate by screening
aer mcp
double mutants by using swarm plate assays.
PaTrx1 and PaTrx3, Two Cytosolic Thioredoxins of the Filamentous Ascomycete
Podospora anserina
Involved in Sexual Development and Cell Degeneration
Authors: Malagnac Fabienne , Klapholz Benjamin , Silar Philippe 
Published: October 2007

ABSTRACT

In various organisms, thioredoxins are known to be involved in the reduction of protein disulfide bonds and in protecting the cell from oxidative stress. Genes encoding thioredoxins were found by searching the complete genome sequence of the filamentous ascomycete
Podospora anserina
. Among them, PaTrx1, PaTrx2, and PaTrx3 are predicted to be canonical cytosolic proteins without additional domains. Targeted disruption of Pa
Trx1
, Pa
Trx2
, and Pa
Trx3
shows that PaTrx1 is the major thioredoxin involved in sulfur metabolism. Deletions have no effect on peroxide resistance; however, data show that either PaTrx1 or PaTrx3 is necessary for sexual reproduction and for the development of the crippled growth cell degeneration (CG), processes that also required the PaMpk1 mitogen-activated protein kinase (MAPK) pathway. Since Pa
Trx1
Pa
Trx3
mutants show not an enhancement but rather an impairment in CG, it seems unlikely that PaTrx1 and PaTrx3 thioredoxins participate in the inhibition of this MAPK pathway. Altogether, these results underscore a role for thioredoxins in fungal development.
A Rho3 Homolog Is Essential for Appressorium Development and Pathogenicity of
Magnaporthe grisea
Authors: Zheng Wu , Chen Jisheng , Liu Wende , Zheng Shiqin , Zhou Jie , Lu Guodong , Wang Zonghua 
Published: October 2007

ABSTRACT

The small GTPase Rho3 is conserved in fungi and plays a key role in the control of cell polarity and exocytosis in yeast. In this report, we show that a Rho3 homolog, MgRho3, is dispensable for polarized hyphal growth in the rice blast fungus
Magnaporthe grisea
. However, MgRho3 is required for plant infection. Appressoria formed by the Mg
rho3
deletion mutants are morphologically abnormal and defective in plant penetration. Conidia of the Mg
rho3
deletion mutants are narrower than those of the wild-type strain and delayed in germination. Transformants expressing a dominant negative Mg
rho3
allele exhibit similar phenotypes as the Mg
rho3
deletion mutant, while transformants expressing a constitutively active allele of Mg
Rho3
can produce normal conidia but remain defective in appressorium formation and plant infection. In contrast, overexpression of wild-type Mg
Rho3
increases the infectivity of
M. grisea
. Our results reveal a new role for the conserved Rho3 as a critical regulator of developmental processes and pathogenicity of
M. grisea
.
Formation of Atroviridin by
Hypocrea atroviridis
Is Conidiation Associated and Positively Regulated by Blue Light and the G Protein GNA3
Authors: Komon-Zelazowska Monika , Neuhof Torsten , Dieckmann Ralf , von Döhren Hans , Herrera-Estrella Alfredo , Kubicek Christian P. , Druzhinina Irina S. 
Published: October 2007

ABSTRACT

Species of the mycoparasitic fungal genus
Hypocrea/Trichoderma
are prominent producers of peptaibols, a class of small linear peptides of fungal origin. Some of these peptaibols have been shown to act synergistically with cell-wall-degrading enzymes in the inhibition of the growth of other fungi in vitro and in vivo. Here we present the structure of the
Hypocrea atroviridis
peptaibol synthetase gene (
pbs1
), deduced from the genome sequence of
H. atroviridis
. It consists of 19 typical peptide synthetase modules with the required additional modifying domains at the N and C termini. Phylogenetic and similarity analyses of the individual amino acid-activating modules is consistent with its ability to synthesize atroviridins. Matrix-assisted laser desorption ionization-time of flight mass spectrometry of surface-grown cultures of
H. atroviridis
showed that no peptaibols were formed during vegetative growth, but a microheterogenous mixture of atroviridins accumulated when the colonies started to sporulate. This correlation between sporulation and atroviridin formation was shown to be independent of the pathway inducing sporulation (i.e., light, mechanical injury and carbon starvation, respectively). Atroviridin formation was dependent on the function of the two blue light regulators, BLR1 and BLR2, under some but not all conditions of sporulation and was repressed in a
pkr1
(regulatory subunit of protein kinase A) antisense strain with constitutively active protein kinase A. Conversely, however, loss of function of the Gα-protein GNA3, which is a negative regulator of sporulation and leads to a hypersporulating phenotype, fully impairs atroviridin formation. Our data show that formation of atroviridin by
H. atroviridis
occurs in a sporulation-associated manner but is uncoupled from it at the stage of GNA3.
Endoplasmic Reticulum α-Glycosidases of
Candida albicans
Are Required for N Glycosylation, Cell Wall Integrity, and Normal Host-Fungus Interaction
Authors: Mora-Montes Héctor M. , Bates Steven , Netea Mihai G. , Díaz-Jiménez Diana F. , López-Romero Everardo , Zinker Samuel , Ponce-Noyola Patricia , Kullberg Bart Jan , Brown Alistair J. P. , Odds Frank C. , Flores-Carreón Arturo , Gow Neil A. R. 
Published: October 2007

ABSTRACT

The cell surface of
Candida albicans
is enriched in highly glycosylated mannoproteins that are involved in the interaction with the host tissues. N glycosylation is a posttranslational modification that is initiated in the endoplasmic reticulum (ER), where the Glc
3
Man
9
GlcNAc
2
N-glycan is processed by α-glucosidases I and II and α1,2-mannosidase to generate Man
8
GlcNAc
2
. This N-oligosaccharide is then elaborated in the Golgi to form N-glycans with highly branched outer chains rich in mannose. In
Saccharomyces cerevisiae, CWH41, ROT2
, and
MNS1
encode for α-glucosidase I, α-glucosidase II catalytic subunit, and α1,2-mannosidase, respectively. We disrupted the
C. albicans CWH41, ROT2
, and
MNS1
homologs to determine the importance of N-oligosaccharide processing on the N-glycan outer-chain elongation and the host-fungus interaction. Yeast cells of Ca
cwh41
Δ, Ca
rot2
Δ, and Ca
mns1
Δ null mutants tended to aggregate, displayed reduced growth rates, had a lower content of cell wall phosphomannan and other changes in cell wall composition, underglycosylated β-
N
-acetylhexosaminidase, and had a constitutively activated PKC-Mkc1 cell wall integrity pathway. They were also attenuated in virulence in a murine model of systemic infection and stimulated an altered pro- and anti-inflammatory cytokine profile from human monocytes. Therefore, N-oligosaccharide processing by ER glycosidases is required for cell wall integrity and for host-fungus interactions.
Burkholderia cenocepacia
C5424 Produces a Pigment with Antioxidant Properties Using a Homogentisate Intermediate
Authors: Keith Karen E. , Killip Lauren , He Panqing , Moran Graham R. , Valvano Miguel A. 
Published: October 2007

ABSTRACT

Burkholderia cenocepacia
is a gram-negative opportunistic pathogen that belongs to the
Burkholderia cepacia
complex.
B. cenocepacia
can survive intracellularly within phagocytic cells, and some epidemic strains produce a brown melanin-like pigment that can scavenge free radicals, resulting in the attenuation of the host cell oxidative burst. In this work, we demonstrate that the brown pigment produced by
B. cenocepacia
C5424 is synthesized from a homogentisate (HGA) precursor. The disruption of BCAL0207 (
hppD
) by insertional inactivation resulted in loss of pigmentation. Steady-state kinetic analysis of the BCAL0207 gene product demonstrated that it has 4-hydroxyphenylpyruvic acid dioxygenase (HppD) activity. Pigmentation could be restored by complementation providing
hppD
in
trans
. The
hppD
mutant was resistant to paraquat challenge but sensitive to H
2
O
2
and to extracellularly generated superoxide anions. Infection experiments in RAW 264.7 murine macrophages showed that the nonpigmented bacteria colocalized in a dextran-positive vacuole, suggesting that they are being trafficked to the lysosome. In contrast, the wild-type strain did not localize with dextran. Colocalization of the nonpigmented strain with dextran was reduced in the presence of the NADPH oxidase inhibitor diphenyleneiodonium, and also the inducible nitric oxide inhibitor aminoguanidine. Together, these observations suggest that the brown pigment produced by
B. cenocepacia
C5424 is a pyomelanin synthesized from an HGA intermediate that is capable of protecting the organism from in vitro and in vivo sources of oxidative stress.
Molecular Basis of the Defective Heat Stress Response inMycobacterium leprae
Authors: Williams Diana L. , Pittman Tana L. , Deshotel Mike , Oby-Robinson Sandra , Smith Issar , Husson Robert 
Published: October 2007

ABSTRACTMycobacterium leprae, a major human pathogen, grows poorly at 37°C. The basis for its inability to survive at elevated temperatures was investigated. We determined thatM. lepraelacks a protective heat shock response as a result of the lack of transcriptional induction of the alternative sigma factor genessigEandsigBand the major heat shock operons, HSP70 and HSP60, even though heat shock promoters and regulatory circuits for these genes appear to be intact.M. leprae sigEwas found to be capable of complementing the defective heat shock response of mycobacterialsigEknockout mutants only in the presence of a functional mycobacterialsigH, which orchestrates the mycobacterial heat shock response. Since thesigHofM. lepraeis a pseudogene, these data support the conclusion that a key aspect of the defective heat shock response inM. lepraeis the absence of a functionalsigH. In addition, 68% of the genes induced during heat shock inM. tuberculosiswere shown to be either absent from theM. lepraegenome or were present as pseudogenes. Among these is thehsp/acr2gene, whose product is essential forM. tuberculosissurvival during heat shock. Taken together, these results suggest that the reduced ability ofM. lepraeto survive at elevated temperatures results from the lack of a functional transcriptional response to heat shock and the absence of a full repertoire of heat stress response genes, includingsigH.
Direct Transcriptional Control of the Plasminogen Activator Gene of
Yersinia pestis
by the Cyclic AMP Receptor Protein
Authors: Kim Tae-Jong , Chauhan Sadhana , Motin Vladimir L. , Goh Ee-Been , Igo Michele M. , Young Glenn M. 
Published: October 2007

ABSTRACT

Horizontal gene transfer events followed by proper regulatory integration of a gene drive rapid evolution of bacterial pathogens. A key event in the evolution of the highly virulent plague bacterium
Yersinia pestis
was the acquisition of plasmid pPCP1, which carries the plasminogen activator gene,
pla
. This promoted the bubonic form of the disease by increasing bacterial dissemination from flea bite sites and incidentally enhanced replication in respiratory airways during pneumonic infection. We determined that expression of
pla
is controlled by the global regulator cyclic AMP (cAMP) receptor protein (Crp). This transcription factor is well conserved among distantly related bacteria, where it acts as a soluble receptor for the ubiquitous signaling molecule cAMP and controls a global network of metabolic and stress-protective genes. Crp has a similar physiological role in
Y. pestis
since loss of its function resulted in an inability to metabolize a variety of nonglucose substrates. Activation of
pla
expression requires a transcription activation element of the
pla
promoter that serves as a Crp binding site. Crp interaction with this site was demonstrated to occur only in the presence of cAMP. Alteration of the Crp binding site nucleotide sequence prevented in vitro formation of Crp-DNA complexes and inhibited in vivo expression of
pla
. The placement of
pla
under direct regulatory control of Crp highlights how highly adapted pathogens integrate laterally acquired genes to coordinate virulence factor expression with global gene networks to maintain homeostasis through the infectious life cycle.
Regulation of Multidrug Efflux Systems Involved in Multidrug and Metal Resistance of
Salmonella enterica
Serovar Typhimurium
Authors: Nishino Kunihiko , Nikaido Eiji , Yamaguchi Akihito 
Published: October 2007

ABSTRACT

Multidrug-resistant strains of
Salmonella
are now encountered frequently, and the rates of multidrug resistance have increased considerably in recent years. Here, we report that the two-component regulatory system BaeSR increases multidrug and metal resistance in
Salmonella
through the induction of drug efflux systems. Screening of random fragments of genomic DNA for the ability to increase β-lactam resistance in
Salmonella enterica
led to the isolation of a plasmid containing
baeR
, which codes for the response regulator of BaeSR. When overexpressed,
baeR
significantly increased the resistance of the Δ
acrB
strain to oxacillin, cloxacillin, and nafcillin.
baeR
overexpression conferred resistance to novobiocin and deoxycholate, as well as to β-lactams in
Salmonella
. The increase in drug resistance caused by
baeR
overexpression was completely suppressed by deletion of the multifunctional outer membrane channel gene
tolC
. TolC interacts with different drug efflux systems. Among the nine drug efflux systems in
Salmonella
, quantitative real-time PCR analysis showed that BaeR induced the expression of
acrD
and
mdtABC
. Double deletion of these two genes completely suppressed BaeR-mediated multidrug resistance, whereas single deletion of either gene did not. The promoter regions of
acrD
and
mdtABC
harbor binding sites for the response regulator BaeR, which activates
acrD
and
mdtABC
transcription in response to indole, copper, and zinc. In addition to their role in multidrug resistance, we found that BaeSR, AcrD, and MdtABC contribute to copper and zinc resistance in
Salmonella
. Our results indicate that the BaeSR system increases multidrug and metal resistance in
Salmonella
by inducing the AcrD and MdtABC drug efflux systems. We found a previously uncharacterized physiological role for the AcrD and MdtABC multidrug efflux systems in metal resistance.