bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Use of Ground‐Water Flow Models for Estimating Lake Seepage Rates
Authors: Munter James A. , Anderson Mary P. 
Published: July 2006

ABSTRACTGround‐water flow models developed for the flow systems around Bass Lake and Nepco Lake, Wisconsin, show that models can be useful tools for estimating lake seepage rates. A two‐dimensional profile model for Bass Lake illustrates that the ratio of horizontal to vertical hydraulic conductivity of the aquifer around the lake is related to both the magnitude of vertical hydraulic gradients near the lake and the distribution of seepage from the lake as a function of distance from shore. The model also shows that it is important to know the vertical hydraulic conductivity of littoral lake‐bed sediments to estimate lake seepage rates.A three‐dimensional model constructed for an unusual ground‐water flow system around Nepco Lake provides a more realistic simulation of the flow system than does a comparable two‐dimensional model. Both models were useful for identifying additional data that could be used to quantify the ground‐water portion of the lake's water budget more accurately. It is suggested that a combination of two‐and/or three‐dimensional models could be used to estimate seepage rates at many lakes for which sufficient data exist.
Statistical Considerations and Sampling Techniques for Ground‐Water Quality Monitoring
Authors: Nelson James D. , Ward Robert C. 
Published: July 2006

ABSTRACTRecent emphasis on the need to protect ground‐water quality has resulted in an increased interest in ground‐water quality monitoring, particularly that monitoring performed in support of a regulatory ground‐water quality management program. Such monitoring must involve intensive surveys or special studies, as well as routine trend types of sampling. In both cases, adequate monitoring strategies require careful consideration of the statistical aspects of sampling theory.The purpose of this paper is to present statistical concepts that should be incorporated in the initial planning of a ground‐water quality monitoring program.The means of incorporating statistical theory into ground‐water quality monitoring suggested in this paper involves selecting the number of samples required based on a specified confidence interval about the mean of the variable under consideration. This approach requires that the variance of the sample mean be known. The expression for Var(x̄) will depend on the correlation structure of the population in question. If the observations taken can be assumed independent in both space and time (i.e., no spatial or serial correlation exists), then the number of samples required can be determined in a very straightforward manner. However, if the samples are correlated, part of the information contained in one observation will be contained in other observations as well. As a result, the sample size must be increased in order to achieve the same level of information that would be obtained in uncorrelated observations.Various sampling techniques can be employed in a ground‐water monitoring plan, including simple random sampling, systematic sampling, and stratified random sampling. Each technique has certain advantages and disadvantages with regard to ground‐water monitoring. An overall monitoring program should incorporate the most effective sampling techniques in order to achieve optimum information content from a minimum number of samples.
Salt‐Water Intrusion in the Costa de Hermosillo, Mexico: A Numerical Analysis of Water Management Proposals
Authors: Andrews Robert W. 
Published: July 2006

ABSTRACTAs a result of anthropogenic discharges of ground water far exceeding natural recharge, the Costa de Hermosillo aquifer is being actively intruded by salt water. Because this aquifer is utilized as the sole source of irrigation water for one of Mexico's principal agricultural districts, the application of any future management scheme to control this intrusion must be closely evaluated prior to implementation. A hydrologic and water quality simulation model is applied to the Costa de Hermosillo aquifer to assess the areal and temporal variations in head, velocity, and concentration as a result of changes in the present discharge distribution. The known hydrologic conditions are reproduced as a means of calibrating the model. Only qualitative statements on the future behavior of the aquifer are possible due to the uncertainty of the magnitude of various aquifer parameters and initial conditions. The model employed in this study is found to be a useful technique for the analysis of the effects of the proposed pumping stresses.
Oestrogen status in relation to the early training responses in human thumb adductor muscles
Authors: Onambele G. N. L. , Bruce S. A. , Woledge R. C. 
Published: July 2006

AbstractAims:  The aims of this study were to identify the mechanisms for the early response to training in women of different oestrogen status and to determine whether any oestrogen and exercise effects on these would be additive.Methods:  We monitored training (ten 5‐s contractions per day for 12 weeks)‐induced changes in the size, strength, voluntary activation capacity and index of crossbridge force state (i.e. rapid stretch to isometric torque ratio), in the thumb adductor muscles of postmenopausal [eight who had never used, and 14 who were using, hormone replacement therapy (HRT)] and seven premenopausal eumenorrhoeic women. The contralateral untrained muscle was used as a control.Results:  There was a significant effect of oestrogen status on the magnitude of training‐induced strength increment, with the non‐HRT postmenopausal group exhibiting the greatest benefits (28 ± 6%, P = 0.024) from training. There were no significant or commensurate changes in either cross‐sectional area or voluntary activation capacity. The index of crossbridge force state improved most in the no‐HRT group (19 ± 7%, P < 0.05).Conclusions:  Presence, rather than absence of oestrogen, is associated with relatively higher muscle function which limits the potential for any further training‐induced increments in muscle performance, as would be expected if the muscle strengthening actions of training and oestrogen share a common, partially saturable physiological pathway. The mechanism that is involved in the early training‐induced strength increment in the three differing oestrogen groups cannot be due to increased size or recruitment. It would appear instead that increased motor unit firing frequency is involved.
Comparison of radiography and magnetic resonance imaging for evaluating the extent of nasal neoplasia in dogs
Authors: Petite A. F. B. , Dennis R. 
Published: July 2006

Objectives:Magnetic resonance imaging (MRI) is increasingly used in veterinary practice and, in some centres, is part of the diagnostic work‐up of small animals with nasal disease. However, there are no published studies which critically evaluate the use of magnetic resonance imaging for this purpose. The purpose of this work was to assess the changes seen using magnetic resonance imaging and to compare them with radiography.Methods:The study included 12 dogs that had undergone both radiography and magnetic resonance imaging of the nasal cavity and had a histopathological diagnosis of malignant nasal neoplasia. Two pairs of board‐certified radiologists scored the radiographs and the MRI scans, evaluating 10 signs of abnormality using a simple scoring system. Magnetic resonance imaging features were described in detail, and radiographic and magnetic resonance imaging scores for each sign as well as total scores were compared.Results:Magnetic resonance imaging often showed that the tumour was more extensive than it had appeared on radiography but occasionally showed that radiographs had overestimated its size. Although radiography was reliable for assessment of the presence and size of a mass and for the extent of turbinate destruction, it usually failed to show occlusion of the major airway passages that were evident on magnetic resonance imaging. Extension of the tumour into the opposite nasal cavity, frontal sinus, orbit and cranial cavity was shown much better on magnetic resonance imaging.ClinicalSignificance:Minor but significant extension beyond the nasal cavity, which is important for treatment planning and prognosis, requires magnetic resonance imaging for demonstration, although radiography shows major changes reliably.
16S rRNA Phylogenetic Investigation of the Candidate Division “
Korarchaeota
”
Authors: Auchtung Thomas A. , Takacs-Vesbach Cristina D. , Cavanaugh Colleen M. 
Published: July 2006

ABSTRACT

The environmental distribution and phylogeny of “
Korarchaeota
,” a proposed ancient archaeal division, was investigated by using the 16S rRNA gene framework.
Korarchaeota
-specific primers were designed based on previously published sequences and used to screen a variety of environments.
Korarchaeota
16S rRNA genes were amplified exclusively from high temperature Yellowstone National Park hot springs and a 9°N East Pacific Rise deep-sea hydrothermal vent. Phylogenetic analyses of these and all available sequences suggest that
Korarchaeota
exhibit a high level of endemicity.
Perpetuation of the Lyme Disease Spirochete
Borrelia lusitaniae
by Lizards
Authors: Richter Dania , Matuschka Franz-Rainer 
Published: July 2006

ABSTRACT

To determine whether the Lyme disease spirochete
Borrelia lusitaniae
is associated with lizards, we compared the prevalence and genospecies of spirochetes present in rodent- and lizard-associated ticks at a site where this spirochete frequently infects questing ticks. Whereas questing nymphal
Ixodes ricinus
ticks were infected mainly by
Borrelia afzelii
, one-half of the infected adult ticks harbored
B. lusitaniae
at our study site. Lyme disease spirochetes were more prevalent in sand lizards (
Lacerta agilis
) and common wall lizards (
Podarcis muralis
) than in small rodents. Although subadult ticks feeding on rodents acquired mainly
B. afzelii
, subadult ticks feeding on lizards became infected by
B. lusitaniae
. Genetic analysis confirmed that the spirochetes isolated from ticks feeding on lizards are members of the
B. lusitaniae
genospecies and resemble type strain PotiB2. At our central European study site, lizards, which were previously considered zooprophylactic for the agent of Lyme disease, appear to perpetuate
B. lusitaniae
.
Diversity of Microcystin-Producing Cyanobacteria in Spatially Isolated Regions of Lake Erie
Authors: Rinta-Kanto Johanna M. , Wilhelm Steven W. 
Published: July 2006

ABSTRACT

The diversity of microcystin-producing cyanobacteria in the western basin of Lake Erie was studied using sequence analysis of
mcyA
gene fragments. Distinct populations of potentially toxic
Microcystis
and
Planktothrix
were found in spatially isolated locations. This study highlights previously undocumented diversity of potentially toxic cyanobacteria.
Infection Paradox: High Abundance but Low Impact of Freshwater Benthic Viruses
Authors: Filippini Manuela , Buesing Nanna , Bettarel Yvan , Sime-Ngando Télesphore , Gessner Mark O. 
Published: July 2006

ABSTRACT
The discovery of an abundant and diverse virus community in oceans and lakes has profoundly reshaped ideas about global carbon and nutrient fluxes, food web dynamics, and maintenance of microbial biodiversity. These roles are exerted through massive viral impact on the population dynamics of heterotrophic bacterioplankton and primary producers. We took advantage of a shallow wetland system with contrasting microhabitats in close proximity to demonstrate that in marked contrast to pelagic systems, viral infection, determined directly by transmission electron microscopy, and consequently mortality of prokaryotes were surprisingly low in benthic habitats in all seasons. This was true even though free viruses were abundant throughout the year and bacterial infection and mortality rates were high in surrounding water. The habitats in which we found this pattern include sediment, decomposing plant litter, and biofilms on aquatic vegetation. Overall, we detected viruses in only 4 of a total of ∼15,000 bacterial cells inspected in these three habitats; for comparison, nearly 300 of ∼5,000 cells suspended in the water column were infected. The strikingly low incidence of impact of phages in the benthos may have important implications, since a major portion of microbial biodiversity and global carbon and nutrient turnover are associated with surfaces. Therefore, if failure to infect benthic bacteria is a widespread phenomenon, then the global role of viruses in controlling microbial diversity, food web dynamics, and biogeochemical cycles would be greatly diminished compared to predictions based on data from planktonic environments.
Sequence Diversity of theBacillus thuringiensisandB. cereusSensu Lato Flagellin (H Antigen) Protein: Comparison with H Serotype Diversity
Authors: Xu Dong , Côté Jean-Charles 
Published: July 2006

ABSTRACTWe set out to analyze the sequence diversity of theBacillus thuringiensisflagellin (H antigen [Hag]) protein and compare it with H serotype diversity. Some otherBacillus cereussensu lato species and strains were added for comparison. The internal sequences of the flagellin (hag) alleles from 80Bacillus thuringiensisstrains and 16 strains from theB. cereussensu lato group were amplified and cloned, and their nucleotide sequences were determined and translated into amino acids. The flagellin allele nucleotide sequences for 10 additional strains were retrieved from GenBank for a total of 106Bacillusspecies and strains used in this study. These included 82B. thuringiensisstrains from 67 H serotypes, 5B. cereusstrains, 3Bacillus anthracisstrains, 3Bacillus mycoidesstrains, 11Bacillus weihenstephanensisstrains, 1Bacillus haloduransstrain, and 1Bacillus subtilisstrain. The first 111 and the last 66 amino acids were conserved. They were referred to as the C1 and C2 regions, respectively. The central region, however, was highly variable and is referred to as the V region. Two bootstrapped neighbor-joining trees were generated: a first one from the alignment of the translated amino acid sequences of the amplified internal sequences of thehagalleles and a second one from the alignment of the V region amino acid sequences, respectively. Of the eight clusters revealed in the tree inferred from the entire C1-V-C2 region amino acid sequences, seven were present in corresponding clusters in the tree inferred from the V region amino acid sequences. With regard toB. thuringiensis, in most cases, different serovars had different flagellin amino acid sequences, as might have been expected. Surprisingly, however, some differentB. thuringiensisserovars shared identical flagellin amino acid sequences. Likewise, serovars from the same H serotypes were most often found clustered together, with exceptions. Indeed, some serovars from the same H serotype carried flagellins with sufficiently different amino acid sequences as to be located on distant clusters. Species-wise,B. halodurans,B. subtilis, andB. anthracisformed specific branches, whereas the other four species, all in theB. cereussensu lato group,B. mycoides,B. weihenstephanensis,B. cereus, andB. thuringiensis, did not form four specific clusters as might have been expected. Rather, strains from any of these four species were placed side by side with strains from the other species. In theB. cereussensu lato group,B. anthracisexcepted, the distribution of strains was not species specific.
Evidence for Existence of “Mesotogas,” Members of the OrderThermotogalesAdapted to Low-Temperature Environments
Authors: Nesbø Camilla L. , Dlutek Marlena , Zhaxybayeva Olga , Doolittle W. Ford 
Published: July 2006

ABSTRACTAll cultivated isolates of the bacterial orderThermotogalesare either thermophiles or hyperthermophiles, butThermotogales16S rRNA gene sequences have been detected in many mesophilic anaerobic and microaerophilic environments, particularly within communities involved in the remediation of pollutants. Here we provide metagenomic evidence for the existence ofThermotogaleslineages, which we informally call “mesotoga,” that are adapted to growth at lower temperatures. Two fosmid clones containing mesotoga DNA, originating from a low-temperature enrichment culture that degrades a polychlorinated biphenyl congener, were sequenced. Phylogenetic analysis clearly puts this bacterial lineage within theThermotogalesorder, with the rRNA gene trees and 21 of 58 open reading frames strongly supporting this relationship. An analysis of protein sequence composition showed that mesotoga proteins are adapted to function at lower temperatures than are their identifiable homologs from thermophilic and hyperthermophilic members of the orderThermotogales, supporting the notion that this bacterium lives and grows optimally at lower temperatures. The phylogenetic analysis suggests that the mesotoga lineage from which our fosmids derive has used both the acquisition of genes from its neighbors and the modification of existing thermophilic sequences to adapt to a mesophilic lifestyle.
Culture-Independent Characterization of the Digestive-Tract Microbiota of the Medicinal Leech Reveals a Tripartite Symbiosis
Authors: Worthen Paul L. , Gode Cindy J. , Graf Joerg 
Published: July 2006

ABSTRACT

Culture-based studies of the microbial community within the gut of the medicinal leech have typically been focused on various
Aeromonas
species, which were believed to be the sole symbiont of the leech digestive tract. In this study, analysis of 16S rRNA gene clone libraries confirmed the presence of
Aeromonas veronii
and revealed a second symbiont, clone PW3, a novel member of the
Rikenellaceae
, within the crop, a large compartment where ingested blood is stored prior to digestion. The diversity of the bacterial community in the leech intestinum was determined, and additional symbionts were detected, including members of the α-, γ-, and δ-
Proteobacteria
,
Fusobacteria
,
Firmicutes
, and
Bacteroidetes
. The relative abundances of the clones suggested that
A. veronii
and the novel clone, PW3, also dominate the intestinum community, while other clones, representing transient organisms, were typically present in low numbers. The identities of these transients varied greatly between individual leeches. Neither time after feeding nor feeding on defibrinated blood caused a change in identity of the dominant members of the microbial communities. Terminal restriction fragment length polymorphism analysis was used to verify that the results from the clone libraries were representative of a larger data set. The presence of a two-member bacterial community in the crop provides a unique opportunity to investigate both symbiont-symbiont and symbiont-host interactions in a natural model of digestive-tract associations.
Purification and Characterization of an Arene
cis
-Dihydrodiol Dehydrogenase Endowed with Broad Substrate Specificity toward Polycyclic Aromatic Hydrocarbon Dihydrodiols
Authors: Jouanneau Yves , Meyer Christine 
Published: July 2006

ABSTRACT

Initial reactions involved in the bacterial degradation of polycyclic aromatic hydrocarbons (PAHs) include a ring-dihydroxylation catalyzed by a dioxygenase and a subsequent oxidation of the dihydrodiol products by a dehydrogenase. In this study, the dihydrodiol dehydrogenase from the PAH-degrading
Sphingomonas
strain CHY-1 has been characterized. The
bphB
gene encoding PAH dihydrodiol dehydrogenase (PDDH) was cloned and overexpressed as a His-tagged protein. The recombinant protein was purified as a homotetramer with an apparent
M
r
of 110,000. PDDH oxidized the
cis
-dihydrodiols derived from biphenyl and eight polycyclic hydrocarbons, including chrysene, benz[
a
]anthracene, and benzo[
a
]pyene, to corresponding catechols. Remarkably, the enzyme oxidized pyrene 4,5-dihydrodiol, whereas pyrene is not metabolized by strain CHY-1. The PAH catechols produced by PDDH rapidly auto-oxidized in air but were regenerated upon reaction of the
o
-quinones formed with NADH. Kinetic analyses performed under anoxic conditions revealed that the enzyme efficiently utilized two- to four-ring dihydrodiols, with

K
m

values in the range of 1.4 to 7.1 μM, and exhibited a much higher Michaelis constant for NAD
+
(

K
m

of 160 μM). At pH 7.0, the specificity constant ranged from (1.3 ± 0.1) × 10
6
M
−1
s
−1
with benz[
a
]anthracene 1,2-dihydrodiol to (20.0 ± 0.8) × 10
6
M
−1
s
−1
with naphthalene 1,2-dihydrodiol. The catalytic activity of the enzyme was 13-fold higher at pH 9.5. PDDH was subjected to inhibition by NADH and by 3,4-dihydroxyphenanthrene, and the inhibition patterns suggested that the mechanism of the reaction was ordered Bi Bi. The regulation of PDDH activity appears as a means to prevent the accumulation of PAH catechols in bacterial cells.
Optimization of a Sampling System for Recovery and Detection of Airborne Porcine Reproductive and Respiratory Syndrome Virus and Swine Influenza Virus
Authors: Hermann J. R. , Hoff S. J. , Yoon K. J. , Burkhardt A. C. , Evans R. B. , Zimmerman J. J. 
Published: July 2006

ABSTRACTThe objective of this research was to optimize sampling parameters for increased recovery and detection of airborne porcine reproductive and respiratory syndrome virus (PRRSV) and swine influenza virus (SIV). Collection media containing antifoams, activated carbons, protectants, and ethylene glycol were evaluated for direct effects on factors impacting the detection of PRRSV and SIV, including virus infectivity, viability of continuous cell lines used for the isolation of these viruses, and performance of reverse transcriptase PCR assays. The results showed that specific compounds influenced the likelihood of detecting PRRSV and SIV in collection medium. A subsequent study evaluated the effects of collection medium, impinger model, and sampling time on the recovery of aerosolized PRRSV using a method for making direct comparisons of up to six treatments simultaneously. The results demonstrated that various components in air-sampling systems, including collection medium, impinger model, and sampling time, independently influenced the recovery and detection of PRRSV and/or SIV. Interestingly, it was demonstrated that a 20% solution of ethylene glycol collected the greatest quantity of aerosolized PRRSV, which suggests the possibility of sampling at temperatures below freezing. Based on the results of these experiments, it is recommended that air-sampling systems be optimized for the target pathogen(s) and that recovery/detection results should be interpreted in the context of the actual performance of the system.
YtjE from
Lactococcus lactis
IL1403 Is a C-S Lyase with α,γ-Elimination Activity toward Methionine
Authors: Martínez-Cuesta M. Carmen , Peláez Carmen , Eagles John , Gasson Michael J. , Requena Teresa , Hanniffy Sean B. 
Published: July 2006

ABSTRACT

Cheese microbiota and the enzymatic conversion of methionine to volatile sulfur compounds (VSCs) are important factors in flavor formation during cheese ripening and the foci in biotechnological approaches to flavor improvement. The product of
ytjE
of
Lactococcus lactis
IL1403, suggested to be a methionine-specific aminotransferase based on genome sequence analysis, was therefore investigated for its role in methionine catabolism. The
ytjE
gene from
Lactococcus lactis
IL1403 was cloned in
Escherichia coli
and overexpressed and purified as a recombinant protein. When tested, the YtjE protein did not exhibit a specific methionine aminotransferase activity. Instead, YtjE exhibited C-S lyase activity and shared homology with the MalY/PatC family of enzymes involved in the degradation of
l
-cysteine,
l
-cystine, and
l
-cystathionine. YtjE was also shown to exhibit α,γ-elimination activity toward
l
-methionine. In addition, gas chromatographic-mass spectrometry analysis showed that YtjE activity resulted in the formation of H
2
S from
l
-cysteine and methanethiol (and its oxidized derivatives dimethyl disulfide and dimethyl trisulfide) from
l
-methionine. Given their significance in cheese flavor development, VSC production by YtjE could offer an additional approach for the development of cultures with optimized aromatic properties.