bluuebunny/crossref_metadata_2025_split huggingface dataset:
Isolation of a Spotted Fever Group Rickettsia,
Rickettsia peacockii
, in a Rocky Mountain Wood Tick,
Dermacentor andersoni
, Cell Line
Authors: Simser Jason A. , Palmer Ann T. , Munderloh Ulrike G. , Kurtti Timothy J. 
Published: July 2002

ABSTRACT

An embryonic cell line (DAE100) of the Rocky Mountain wood tick,
Dermacentor andersoni
, was observed by microscopy to be chronically infected with a rickettsialike organism. The organism was identified as a spotted fever group (SFG) rickettsia by PCR amplification and sequencing of portions of the 16S rRNA, citrate synthase,
Rickettsia
genus-specific 17-kDa antigen, and SFG-specific 190-kDa outer membrane protein A (rOmpA) genes. Sequence analysis of a partial
rompA
gene PCR fragment and indirect fluorescent antibody data for rOmpA and rOmpB indicated that this rickettsia was a strain (DaE100R) of
Rickettsia peacockii
, an SFG species presumed to be avirulent for both ticks and mammals.
R. peacockii
was successfully maintained in a continuous culture of DAE100 cells without apparent adverse effects on the host cells. Establishing cell lines from embryonic tissues of ticks offers an alternative technique for isolation of rickettsiae that are transovarially transmitted.
Identification of Fecal
Escherichia coli
from Humans and Animals by Ribotyping
Authors: Carson C. Andrew , Shear Brian L. , Ellersieck Mark R. , Asfaw Amha 
Published: July 2002

ABSTRACT

Fecal pollution of water resources is an environmental problem of increasing importance. Identification of individual host sources of fecal
Escherichia coli
, such as humans, pets, production animals, and wild animals, is prerequisite to formulation of remediation plans. Ribotyping has been used to distinguish fecal
E. coli
of human origin from pooled fecal
E. coli
isolates of nonhuman origin. We have extended application of this technique to distinguishing fecal
E. coli
ribotype patterns from human and seven individual nonhuman hosts. Classification accuracy was best when the analysis was limited to three host sources. Application of this technique to identification of host sources of fecal coliforms in water could assist in formulation of pollution reduction plans.
Physiological Properties of
Saccharomyces cerevisiae
from Which Hexokinase II Has Been Deleted
Authors: Diderich Jasper A. , Raamsdonk Léonie M. , Kruckeberg Arthur L. , Berden Jan A. , Van Dam Karel 
Published: July 2002

ABSTRACT

Hexokinase II is an enzyme central to glucose metabolism and glucose repression in the yeast
Saccharomyces cerevisiae
. Deletion of
HXK2
, the gene which encodes hexokinase II, dramatically changed the physiology of
S. cerevisiae
. The
hxk2
-null mutant strain displayed fully oxidative growth at high glucose concentrations in early exponential batch cultures, resulting in an initial absence of fermentative products such as ethanol, a postponed and shortened diauxic shift, and higher biomass yields. Several intracellular changes were associated with the deletion of hexokinase II. The
hxk2
mutant had a higher mitochondrial H
+
-ATPase activity and a lower pyruvate decarboxylase activity, which coincided with an intracellular accumulation of pyruvate in the
hxk2
mutant. The concentrations of adenine nucleotides, glucose-6-phosphate, and fructose-6-phosphate are comparable in the wild type and the
hxk2
mutant. In contrast, the concentration of fructose-1,6-bisphosphate, an allosteric activator of pyruvate kinase, is clearly lower in the
hxk2
mutant than in the wild type. The results suggest a redirection of carbon flux in the
hxk2
mutant to the production of biomass as a consequence of reduced glucose repression.
Varied Diazotrophies, Morphologies, and Toxicities of Genetically Similar Isolates of
Cylindrospermopsis raciborskii
(Nostocales, Cyanophyceae) from Northern Australia
Authors: Saker Martin L. , Neilan Brett A. 
Published: July 2002

ABSTRACT

The potentially toxic freshwater cyanobacterium
Cylindrospermopsis raciborskii
has become increasingly prevalent in tropical and temperate water bodies worldwide. This paper investigates the effects of different nitrogen sources (NO
3
−
, NH
4
+
, and omission of a fixed form of nitrogen) on the growth rates, morphologies, and cylindrospermopsin (CYL) concentrations (expressed as a percentage of the freeze-dried weight) of seven
C. raciborskii
isolates obtained from a range of water bodies in northern Australia and grown in batch culture. In general, growth rates were lowest in the absence of a fixed-nitrogen source and highest with NH
4
+
as the nitrogen source. Conversely, the highest concentrations of CYL were recorded in cultures grown in the absence of a fixed-nitrogen source and the lowest were found in cultures supplied with NH
4
+
. Cultures supplied with NO
3
−
were intermediate with respect to both CYL concentration and growth rate. Different nitrogen sources resulted in significant differences in the morphology of
C. raciborskii
trichomes. Most notable were the loss of heterocysts and the tapering of end cells in cultures supplied with NH
4
+
and the statistically significant increase in vegetative cell length (nitrogen depleted < NO
3
−
< NH
4
+
). The morphological changes induced by different nitrogen sources were consistent for all isolates, despite measurable differences in vegetative-cell and heterocyst dimensions among isolates. Such induced morphological variation has implications for
Cylindrospermopsis
taxonomy, given that distinctions between species are based on minor and overlapping differences in cell lengths and widths. The close phylogenetic association among all seven isolates was confirmed by the high level (>99.8%) of similarity of their 16S rRNA gene sequences. Another genetic technique, analysis of the HIP1 octameric-palindrome repeated sequence, showed greater heterogeneity among the isolates and appears to be a useful method for distinguishing among isolates of
C. raciborskii
.
Rapid Identification and Differentiation of the Soft Rot Erwinias by 16S-23S Intergenic Transcribed Spacer-PCR and Restriction Fragment Length Polymorphism Analyses
Authors: Toth I. K. , Avrova A. O. , Hyman L. J. 
Published: July 2002

ABSTRACT

Current identification methods for the soft rot erwinias are both imprecise and time-consuming. We have used the 16S-23S rRNA intergenic transcribed spacer (ITS) to aid in their identification. Analysis by ITS-PCR and ITS-restriction fragment length polymorphism was found to be a simple, precise, and rapid method compared to current molecular and phenotypic techniques. The ITS was amplified from
Erwinia
and other genera using universal PCR primers. After PCR, the banding patterns generated allowed the soft rot erwinias to be differentiated from all other
Erwinia
and non-
Erwinia
species and placed into one of three groups (I to III). Group I comprised all
Erwinia carotovora
subsp.
atroseptica
and subsp.
betavasculorum
isolates. Group II comprised all
E. carotovora
subsp.
carotovora,
subsp.
odorifera
, and subsp.
wasabiae
and
E. cacticida
isolates, and group III comprised all
E. chrysanthemi
isolates. To increase the level of discrimination further, the ITS-PCR products were digested with one of two restriction enzymes. Digestion with
Cfo
I identified
E. carotovora
subsp.
atroseptica
and subsp.
betavasculorum
(group I) and
E. chrysanthemi
(group III) isolates, while digestion with
Rsa
I identified
E. carotovora
subsp.
wasabiae, subsp. carotovora
, and subsp.
odorifera/carotovora
and
E. cacticida
isolates (group II). In the latter case, it was necessary to distinguish
E. carotovora
subsp.
odorifera
and subsp.
carotovora
using the α-methyl glucoside test. Sixty suspected soft rot erwinia isolates from Australia were identified as
E. carotovora
subsp.
atroseptica
,
E. chrysanthemi
,
E. carotovora
subsp.
carotovora
, and non-soft rot species. Ten “atypical”
E. carotovora
subsp.
atroseptica
isolates were identified as
E. carotovora
subsp.
atroseptica
, subsp.
carotovora
, and subsp.
betavasculorum
and non-soft rot species, and two “atypical”
E. carotovora
subsp.
carotovora
isolates were identified as
E. carotovora
subsp.
carotovora
and subsp.
atroseptica
.
Characterization of the Single Superoxide Dismutase of
Staphylococcus xylosus
Authors: Barrière Charlotte , Brückner Reinhold , Talon Régine 
Published: July 2002

ABSTRACT

Staphylococcus xylosus
is a facultative anaerobic bacterium used as a starter culture for fermented meat products. In an attempt to analyze the antioxidant capacities of this organism, the superoxide dismutase (SOD) was characterized.
S. xylosus
contains a single cytoplasmic SOD, which was not inhibited by H
2
O
2
. The SOD activity in crude extracts was completely lost upon metal depletion, but it could be recovered by manganese and very weakly by iron. It is therefore suggested that the
S. xylosus
SOD is a manganese-preferring enzyme. The corresponding gene,
sod
, was isolated from a genomic library of
S. xylosus
DNA and complemented the growth defect of an
Escherichia coli
SOD-deficient mutant. As deduced from the nucleotide sequence,
sod
encodes a protein of 199 amino acids with a molecular mass of 22.5 kDa. Two transcriptional start sites 25 and 120 bp upstream of the
sod
start codon were identified. A terminator-like structure downstream of the gene suggested a monocistronic
sod
mRNA. Regulation of
sod
expression was studied using fusions of the
sod
promoters to a genomic promoterless β-galactosidase gene. The
sod
expression was not affected by manganese and increased slightly with paraquat. It was induced during stationary phase in a complex medium but not in a chemically defined medium. To investigate the physiological role of SOD, a mutant devoid of SOD activity was constructed. Growth experiments showed that
sod
is not essential for aerobic growth in complex medium. However, in chemically defined medium without leucine, isoleucine, and valine, the
sod
mutant hardly grew, in contrast to the wild-type strain. In addition, the mutant was sensitive to hyperbaric oxygen and to paraquat. Therefore,
sod
plays an important role in the protection of
S. xylosus
from oxidative stress.
Lytic and Lysogenic Infection of Diverse
Escherichia coli
and
Shigella
Strains with a Verocytotoxigenic Bacteriophage
Authors: James Chloe E. , Stanley Karen N. , Allison Heather E. , Flint Harry J. , Stewart Colin S. , Sharp Richard J. , Saunders Jon R. , McCarthy Alan J. 
Published: July 2002

ABSTRACT

A verocytotoxigenic bacteriophage isolated from a strain of enterohemorrhagic
Escherichia coli
O157, into which a kanamycin resistance gene (
aph3
) had been inserted to inactivate the verocytotoxin gene (

vt
2

), was used to infect
Enterobacteriaceae
strains. A number of
Shigella
and
E. coli
strains were susceptible to lysogenic infection, and a smooth
E. coli
isolate (O107) was also susceptible to lytic infection. The lysogenized strains included different smooth
E. coli
serotypes of both human and animal origin, indicating that this bacteriophage has a substantial capacity to disseminate verocytotoxin genes. A novel indirect plaque assay utilizing an
E. coli recA441
mutant in which phage-infected cells can enter only the lytic cycle, enabling detection of all infective phage, was developed.
Chimeric
Vitreoscilla
Hemoglobin (VHb) Carrying a Flavoreductase Domain Relieves Nitrosative Stress in
Escherichia coli
: New Insight into the Functional Role of VHb
Authors: Kaur Ramandeep , Pathania Ranjana , Sharma Vishwamitra , Mande Shekhar C. , Dikshit Kanak L. 
Published: July 2002

ABSTRACT

Dimeric hemoglobin (VHb) from the bacterium
Vitreoscilla
sp. strain C1 displays 30 to 53% sequence identity with the heme-binding domain of flavohemoglobins (flavoHbs) and exhibits the presence of potential sites for the interaction with its FAD/NADH reductase partner. The intersubunit contact region of VHb indicates a small interface between two monomers of the homodimer, suggesting that the VHb dimers may dissociate easily. Gel filtration chromatography of VHb exhibited a 25 to 30% monomeric population of VHb, at a low protein concentration (0.05 mg/ml), whereas dimeric VHb remained dominant at a high protein concentration (10 mg/ml). The structural characteristics of VHb suggest that the flavoreductase can also associate and interact with VHb in a manner analogous to flavoHbs and could yield a flavo-VHb complex. To unravel the functional relevance of the VHb-reductase association, the reductase domain of flavoHb from
Ralstonia eutropha
(formerly
Alcaligenes eutrophus
) was genetically engineered to generate a VHb-reductase chimera (VHb-R). The physiological implications of VHb and VHb-R were studied in an
hmp
mutant of
Escherichia coli
, incapable of producing any flavoHb. Cellular respiration the of the
hmp
mutant was instantaneously inhibited in the presence of 10 μM nitric oxide (NO) but remained insensitive to NO inhibition when these cells produced VHb-R. In addition,
E. coli
overproducing VHb-R exhibited NO consumption activity that was two to three times slower in cells overexpressing only VHb and totally undetectable in the control cells. A purified preparation of VHb-R exhibited a three- to fourfold-higher NADH-dependent NO uptake activity than that of VHb alone. Overproduction of VHb-R in the
hmp
mutant of
E. coli
conferred relief from the toxicity of sodium nitroprusside, whereas VHb alone provided only partial benefit under similar condition, suggesting that the association of VHb with reductase improves its capability to relieve the deleterious effect of nitrosative stress. Based on these results, it has been proposed that the unique structural features of VHb may allow it to acquire two functional states in vivo, namely, a single-domain homodimer that may participate in facilitated oxygen transfer or a two-domain heterodimer in association with its partner reductase that may be involved in modulating the cellular response under different environmental conditions. Due to this inherent structural flexibility, it may perform multiple functions in the cellular metabolism of its host. Separation of the oxidoreductase domain from VHb may thus provide a physiological advantage to its host.
Comparison of Soil Bacterial Communities in Rhizospheres of Three Plant Species and the Interspaces in an Arid Grassland
Authors: Kuske Cheryl R. , Ticknor Lawrence O. , Miller Mark E. , Dunbar John M. , Davis Jody A. , Barns Susan M. , Belnap Jayne 
Published: July 2002

ABSTRACT

Soil bacteria are important contributors to primary productivity and nutrient cycling in arid land ecosystems, and their populations may be greatly affected by changes in environmental conditions. In parallel studies, the composition of the total bacterial community and of members of the
Acidobacterium
division were assessed in arid grassland soils using terminal restriction fragment length polymorphism (TRF, also known as T-RFLP) analysis of 16S rRNA genes amplified from soil DNA. Bacterial communities associated with the rhizospheres of the native bunchgrasses
Stipa hymenoides
and
Hilaria jamesii
, the invading annual grass
Bromus tectorum
, and the interspaces colonized by cyanobacterial soil crusts were compared at three depths. When used in a replicated field-scale study, TRF analysis was useful for identifying broad-scale, consistent differences in the bacterial communities in different soil locations, over the natural microscale heterogeneity of the soil. The compositions of the total bacterial community and
Acidobacterium
division in the soil crust interspaces were significantly different from those of the plant rhizospheres. Major differences were also observed in the rhizospheres of the three plant species and were most apparent with analysis of the
Acidobacterium
division. The total bacterial community and the
Acidobacterium
division bacteria were affected by soil depth in both the interspaces and plant rhizospheres. This study provides a baseline for monitoring bacterial community structure and dynamics with changes in plant cover and environmental conditions in the arid grasslands.
Physiological Function of Alcohol Dehydrogenases and Long-Chain (C
30
) Fatty Acids in Alcohol Tolerance of
Thermoanaerobacter ethanolicus
Authors: Burdette D. S. , Jung S.-H. , Shen G.-J. , Hollingsworth R. I. , Zeikus J. G. 
Published: July 2002

ABSTRACT

A mutant strain (39E H8) of
Thermoanaerobacter ethanolicus
that displayed high (8% [vol/vol]) ethanol tolerance for growth was developed and characterized in comparison to the wild-type strain (39E), which lacks alcohol tolerance (<1.5% [vol/vol]). The mutant strain, unlike the wild type, lacked primary alcohol dehydrogenase and was able to increase the percentage of transmembrane fatty acids (i.e., long-chain C
30
fatty acids) in response to increasing levels of ethanol. The data support the hypothesis that primary alcohol dehydrogenase functions primarily in ethanol consumption, whereas secondary alcohol dehydrogenase functions in ethanol production. These results suggest that improved thermophilic ethanol fermentations at high alcohol levels can be developed by altering both cell membrane composition (e.g., increasing transmembrane fatty acids) and the metabolic machinery (e.g., altering primary alcohol dehydrogenase and lactate dehydrogenase activities).
Propionate Formation by
Opitutus terrae
in Pure Culture and in Mixed Culture with a Hydrogenotrophic Methanogen and Implications for Carbon Fluxes in Anoxic Rice Paddy Soil
Authors: Chin Kuk-Jeong , Janssen Peter H. 
Published: July 2002

ABSTRACT

Propionate-forming bacteria seem to be abundant in anoxic rice paddy soil, but biogeochemical investigations show that propionate is not a correspondingly important intermediate in carbon flux in this system. Mixed cultures of
Opitutus terrae
strain PB90-1, a representative propionate-producing bacterium from rice paddy soil, and the hydrogenotrophic
Methanospirillum hungatei
strain SK maintained hydrogen partial pressures similar to those in the soil. The associated shift away from propionate formation observed in these cultures helps to reconcile the disparity between microbiological and biogeochemical studies.
Apoptosis of Primary-Culture Rat Microglial Cells Induced by PathogenicAcanthamoebaspp
Authors: Shin Ho-Joon , Cho Myung-Soo , Kim Hyung-Il , Lee Millina , Park Sun , Sohn Seonghyang , Im Kyung-Il 
Published: July 2002

ABSTRACTTo determine whether trophozoites and lysates of pathogenicAcanthamoebaspp. induce apoptosis in primary-culture microglial cells, transmission electron microscopic (TEM) examinations, assessment of DNA fragmentation by agarose gel electrophoresis, and the TdT-mediated dUTP nick-end labeling assay were performed. When a trophozoite of pathogenicAcanthamoeba culbertsonicame in contact with a microglial cell, the digipodium was observed by TEM. Nuclear chromatin condensation was observed in 10% of microglial cells, while it was not revealed when they were cocultured with weakly pathogenicAcanthamoeba royrebatrophozoites. DNA fragmentation in microglial cells cocultured with theA. culbertsonilysate was detected by electrophoresis, showing DNA ladder formation, whereas it was hardly observed in microglial cells cocultured withA. royreba. DNA fragmentation of microglial cells was also confirmed by flow cytometry analysis. The fluorescence of TdT-stained apoptotic bodies became intensely visible with microglial cells cocultured with theA. culbertsonilysate. In contrast, with microglial cells cocultured with theA. royrebalysate, only a background level of fluorescence of TdT-stained apoptotic bodies was detected. These results suggest that some rat microglial cells cocultured with pathogenicA. culbertsoniundergo cytopathic changes which show the characteristics of the apoptotic process, such as nuclear condensation and DNA fragmentation.
Prevalence of
Chlamydia pneumoniae
and
Mycoplasma pneumoniae
Immunoglobulin G and A Antibodies in a Healthy Finnish Population as Analyzed by Quantitative Enzyme Immunoassays
Authors: Tuuminen Tamara , Varjo Sirpa , Ingman Heidi , Weber Theodor , Oksi Jarmo , Viljanen Matti 
Published: July 2002

ABSTRACT

Chlamydia pneumoniae
and
Mycoplasma pneumoniae
immunoglobulin G (IgG) and IgA antibody seroprevalence rates and antibody levels related to age and gender were studied. The samples (
n
= 742) were collected during a nonepidemic period and analyzed by quantitative enzyme immunoassays (EIAs). Seroprevalence to
C. pneumoniae
was found to increase sharply in young children, and in the 15- to 19-year-old group it reached levels as high as 70 and 60% for IgG and IgA, respectively. After adolescence, seroprevalence showed a transient decrease and then continued to increase, although less dramatically than in early childhood. In the elderly the seroprevalence of IgG antibodies reached 75 and 100% in women and men, respectively. The corresponding rates of IgA antibodies were 73 and 100%. When a randomly selected subgroup of samples (
n
= 66) was analyzed in parallel by a microimmunofluorescence test and an EIA for
C. pneumoniae
IgA antibodies, similar seroprevalence rates were obtained (36 versus 35%). Seroprevalence to
M. pneumoniae
was already found to increase very sharply in 2- to 4-year-old children, reaching 16% for IgG and 8% for IgA. Seroprevalence to
M. pneumoniae
also continued to increase in adolescence, but in contrast to that to
C. pneumoniae
, the increase leveled off at about 40 to 50% in adulthood. In subjects aged over 65 years, prevalence did not exceed 60% for IgG or 35% for IgA. The seroprevalence patterns as well as the medians and variations of levels of
C. pneumoniae
and
M. pneumoniae
IgG antibodies were similar to those of corresponding IgA antibodies. Compared to IgG antibodies, IgA antibodies do not seem to be of additional value in the diagnosis of infections caused by these pathogens when single serum specimens are studied.
Human Dengue Antibodies against Structural and Nonstructural Proteins
Authors: Valdés Katia , Alvarez Mayling , Pupo Maritza , Vázquez Susana , Rodríguez Rayner , Guzmán María G. 
Published: July 2002

ABSTRACT
Antibodies against dengue virus type 2 and 4 proteins in acute-phase sera of 10 primary and 10 secondary dengue fever and dengue hemorrhagic fever patients were studied by Western blotting. In the first group the immune response was barely detectable, while in the second group more proteins were detected, with a very strong reaction. Anti-NS1 and -NS3 antibodies were detected mainly in secondary cases. Anti-E, -NS3, and -NS5 antibodies were detected in a high number of cases. The possibility of implementing early diagnostic assays for antigen detection is suggested.
Genomic Characterization of Porcine Rotaviruses in Italy
Authors: Martella Vito , Pratelli Annamaria , Greco Grazia , Tempesta Maria , Ferrari Maura , Losio Marina Nadia , Buonavoglia Canio 
Published: July 2002

ABSTRACT
A total of 23 rotavirus strains isolated from pigs were analyzed. Twenty strains had been isolated from diarrheic piglets from an outbreak that occurred in northern Italy in 1983. Three strains had been isolated in 1984 from swine herds located in distinct areas of northern Italy. All 23 strains were characterized as type G6P[5] by PCR. The isolation from piglets of rotaviruses displaying typical bovine G- and P-type specificities points out the high frequency of rotavirus transmission between cattle and pigs.