bluuebunny/crossref_metadata_2025 huggingface dataset:
Chemical Composition and Antimicrobial and Antioxidant Activities of Mentha (longifolia L. and viridis) Essential Oils
Authors: Mkaddem Mounira , Bouajila Jalloul , Ennajar Monia , Lebrihi Ahmed , Mathieu Florence , Romdhane Mehrez
Published: August 2009

ABSTRACT:  The study was aimed to investigate essential oil chemical composition (gas chromatography/flame ionization detection [GC‐FID] and gas chromatography/mass spectrometry [GC‐MS]) and antioxidant (1,1‐diphenyl‐2‐picrylhydrazyl free radical (DPPH) and 2,2’‐azinobis‐3‐ethylbenzothiazoline‐6‐sulphonate [ABTS] assays) and antimicrobial (Gram‐positive and Gram‐negative bacteria, fungi, and yeast) activities of essential oils extracted from leaves of Mentha longifolia L. and Mentha viridis. GC‐MS analysis revealed that M. longifolia was constituted by pulegone (54.41%) as a major component followed by isomenthone (12.02%), 1,8‐cineole (7.41%), borneol (6.85%), and piperitenone oxide (3.19%). M. viridis was rich in carvone (50.47%), 1,8‐cineole (9.14%), and limonene (4.87%). The antioxidant activity by ABTS assay showed IC50 values of 476.3 ± 11.7 and 195.1 ± 4.2 mg/L for M. longifolia and M. viridis, respectively, the DPPH assays have resulted in a moderate IC50 (>8000 mg/L and 3476.3 ± 133 mg/L for M. longifolia and M. viridis, respectively). Antimicrobial activity showed that Listeria monocytogenes and Klebsiella pneumoniae bacteria were more inhibited by the 2 essential oils tested. Escherichia coli was least susceptible. A strong activity was also observed on fungi and yeasts. Carvone, thymol, and piperitone oxide have not been detected in Tunisian M. longifolia. Camphor is reported for the 1st time for M. viridis. Antioxidant and antibacterial activities were correlated to chemical composition.
Antitumor and Antiangiogenic Activity of Soy Phytoestrogen on 7,12‐Dimethylbenz[α]anthracene‐Induced Mammary Tumors Following Ovariectomy in Sprague–Dawley Rats
Authors: Kang Xinmei , Jin Shi , Zhang Qingyuan
Published: August 2009

ABSTRACT:  Soy phytoestrogen is often used as hormone replacement therapy to alleviate the symptoms of menopause in postmenopausal women. Since estrogen has been considered as an important risk factor for the development of breast carcinoma, we need to know whether it is safe for these postmenopausal women with breast cancer to take soy foods that are rich in phytoestrogen. In the present study, we investigated the efficacy of soy phytoestrogen on tumor proliferation, apoptosis, and angiogenesis in mammary tumors that had already formed in ovariectomized rats. We found that soy phytochemical extraction inhibited proliferation and induced apoptosis in vitro and in vivo, and it demonstrated better antitumor effects than single phytoestrogen. Soy phytochemical extraction also produced surprisingly good antiangiogenic effects, which were evidenced by lower microvascular density, reduced plasma vascular endothelial growth factor, and increased plasma endostatin levels. Our findings suggest that soy phytochemical extraction exerts significant antitumor and antiangiogenic activity in a postmenopausal animal model with breast cancer.
Is Left Ventricular Hypertrophy Regression Important? Does the Tool Used to Detect It Matter?
Authors: Nadour Wadih , Biederman Robert W. W.
Published: August 2009

Left ventricular hypertrophy (LVH) has been demonstrated to define an adverse cardiovascular prognosis. However, due to poor noninvasive tools in which to accurately define LVH, the clinical manifestations dictate an inexact manner in which to either initiate therapy or to gauge the success of LVH regression. Herein, the authors define the current state of imaging modalities available to interrogate LVH and its regression, but concentrating chiefly on the “gold standard” of cardiovascular magnetic resonance imaging (CMR). The authors review the data demonstrating the importance of LVH regression. Additionally, they highlight the strengths and weaknesses of CMR via several pinnacle studies that demonstrate the ease, efficiency, and accuracy of this new noninvasive reproducible and available tool to relatively inexpensively delineate LVH. Finally, upon pharmacologic administration of an antihypertensive regimen, the authors, for the first time, define a goal of left ventricular mass reduction (in grams) for echocardiography and CMR based in part on Framingham data aiming at improving cardiovascular risk.
The mammalian mineralocorticoid receptor: tying down a promiscuous receptor
Authors: Gomez‐Sanchez Elise P.
Published: August 2009

The mineralocorticoid receptor (MR) has been called a promiscuous receptor because its intrinsic affinity for aldosterone, cortisol and corticosterone is similar. Since glucocorticoids circulate in concentrations 100‐ to 1000‐fold those of aldosterone, stoichiometry dictates that MR should be activated by glucocorticoids, not aldosterone, yet MRs are expressed in many tissues and regulate diverse functions, many of them under the regulation of the renin–angiotensin–aldosterone system. A relatively small number of brain MRs are aldosterone selective and modulate blood pressure. Evidence for possible mechanisms conferring ligand specificity in the context of mineralocorticoid‐induced hypertension and the brain are discussed. These include factors (or mechanisms) intrinsic to the receptor, such as alternative splice variants and translation start sites, and extrinsic to the MR, including differential access through the blood–brain barrier, differential recruitment of co‐regulators and scaffolding proteins, 11β‐steroid dehydrogenase activity, synthesis of potent acylated aldosterone derivatives and the synthesis of relevant amounts of aldosterone in areas of the brain that modulate blood pressure.
Mineralocorticoid receptors, inflammation and sympathetic drive in a rat model of systolic heart failure
Authors: Felder Robert B.
Published: August 2009

Appreciation for the role of aldosterone and mineralocorticoid receptors in cardiovascular disease is accelerating rapidly. Recent experimental work has unveiled a strong relationship between brain mineralocorticoid receptors and sympathetic drive, an important determinant of outcome in heart failure and hypertension. Two putative mechanisms are explored in this manuscript. First, brain mineralocorticoid receptors may influence sympathetic discharge by regulating the release of pro‐inflammatory cytokines into the circulation. Blood‐borne pro‐inflammatory cytokines act upon receptors in the microvasculature of the brain to induce cyclooxygenase‐2 activity and the production of prostaglandin E2, which penetrates the blood–brain barrier to activate the sympathetic nervous system. Second, brain mineralocorticoid receptors may influence sympathetic drive by upregulating the activity of the brain renin–angiotensin system, resulting in NAD(P)H oxidase‐dependent superoxide production. A potential role for superoxide‐dependent mitogen‐activated protein kinase signalling pathways in the regulation of sympathetic nerve activity is also considered. Other potential downstream signalling mechanisms contributing to mineralocorticoid receptor‐mediated sympathetic excitation are under investigation.
Influence of central command on cerebral blood flow at the onset of exercise in women
Authors: Sato Kohei , Moriyama Mayumi , Sadamoto Tomoko
Published: August 2009

This study evaluated the role of central command in the regulation of common carotid artery blood flow
and middle cerebral artery mean flow velocity (VMCA) at the onset of arm exercise. Eleven young women performed 2 min voluntary elbow flexion and extension exercise with no load (VOL) that was considered to activate both central command and the muscle mechanoreflex, and 2 min passive elbow flexion and extension exercise (PAS) that was considered to activate only the muscle mechanoreflex. Immediately before the onset of VOL,
and VMCA began to increase from the baseline and peaked 5 s thereafter (mean ±s.d.; 20 ± 5 and 14 ± 5%, respectively; P < 0.05). Also, VOL increased heart rate (9 ± 2%; P < 0.05) and cardiac output (16 ± 3%; P < 0.05). Indexes of the cerebrovascular resistance (MAP/
and MAP/VMCA) were reduced at the onset of VOL (−13 ± 4 and −12 ± 4%, respectively; P < 0.05). However, there were no significant changes in these parameters during PAS. These results suggest that central command plays an important role in the increase of cerebral blood flow at the onset of voluntary exercise.
Central command and the increase in middle cerebral artery blood flow velocity during static arm exercise in women
Authors: Sato Kohei , Sadamoto Tomoko , Ueda‐Sasahara Chihoko , Shibuya Kenichi , Shimizu‐Okuyama Shizuyo , Osada Takuya , Kamo Mifuyu , Saito Mitsuru , Kagaya Atsuko
Published: August 2009

We examined the role of central command in static exercise‐induced increase in middle cerebral artery mean blood flow velocity (VMCA). Eleven young female subjects performed static elbow flexion for 2 min at 30% maximal voluntary contraction without (control exercise; CONT) and with vibrations to the biceps brachii tendon (EX+VIB) in order to reduce the effort needed to maintain the set contraction intensity. The rating of perceived exertion in exercising muscle (Arm RPE) at the end of EX+VIB was lower than that of CONT (mean ±s.d.; 4.8 ± 1.1 for CONT versus 3.5 ± 1.0 for EX+VIB; P < 0.05). The increases in mean arterial pressure (36 ± 8 versus 22 ± 7%; P < 0.05), heart rate (36 ± 16 versus 21 ± 7%; P < 0.05) and cardiac output (56 ± 26 versus 39 ± 14%; P < 0.05) during EX+VIB were also lower than those during CONT. Similarly, the increase in the VMCA during EX+VIB was lower than that during CONT (29 ± 5 versus 17 ± 14%; P < 0.05). These results suggest that the influence of central command contributes to cerebral blood flow regulation during static exercise and the decrease in VMCA is likely to be caused by attenuated brain activation in the central command network and/or by the reduction in cardiac output.
Digital Soil Map of the World
Authors: Sanchez Pedro A. , Ahamed Sonya , Carré Florence , Hartemink Alfred E. , Hempel Jonathan , Huising Jeroen , Lagacherie Philippe , McBratney Alex B. , McKenzie Neil J. , Mendonça-Santos Maria de Lourdes , Minasny Budiman , Montanarella Luca , Okoth Peter , Palm Cheryl A. , Sachs Jeffrey D. , Shepherd Keith D. , Vågen Tor-Gunnar , Vanlauwe Bernard , Walsh Markus G. , Winowiecki Leigh A. , Zhang Gan-Lin
Published: August 2009

Increased demand and advanced techniques could lead to more refined mapping and management of soils.
The Biofuels Landscape Through the Lens of Industrial Chemistry
Authors: Willems Paul A.
Published: August 2009

Replacing petroleum feedstock with biomass in the production of fuels and value-added chemicals carries considerable appeal. As in industrial chemistry more broadly, high-throughput experimentation has greatly facilitated innovation in small-scale exploration of biomass production and processing. Yet biomass is hard to transport, potentially hindering the integration of manufacturing-scale processes. Moreover, the path from laboratory breakthrough to commercial production remains as tortuous as ever.
An Alternative DNA Structure Is Necessary for Pilin Antigenic Variation in
Neisseria gonorrhoeae
Authors: Cahoon Laty A. , Seifert H. Steven
Published: August 2009

Taking Shape

DNA recombination mechanisms enable certain pathogens to modify the proteins on their outer surfaces by rearranging their genes and so avoid repeated detection by the immune system.
Cahoon and Seifert
(p.
764
) have found that antigenic variation of a single genetic locus in the human pathogen
Neisseria gonorrhoeae
is triggered by a specific cis-acting DNA element. This 16–base pair DNA sequence formed an unusual DNA structure in vitro; a guanine quartet (G4), which has been implicated in only a few other biological processes. The G4 forming sequence is required for processing the gene conversion reaction leading to antigenic variation. These findings have implications both for understanding mechanisms of DNA recombination and its role in microbial pathogenesis.
Bridging an Ocean

Re:Design
by Craig Baxter; directed by Paul Bourne

Menagerie Theatre Company, ADC Theatre, University of Cambridge, UK. July 2009. Darwin Festival Fringe Programme.
Authors: Thomas Claire
Published: August 2009

Baxter constructed his play from correspondence between Darwin and the devoutly Christian American botanist Asa Gray.
Worries About Africa as Pandemic Marches On
Authors: Enserink Martin
Published: August 2009

With its poor health infrastructure and lack of surveillance, experts fear that Africa—especially south of the Sahara—might be harder hit by the 2009 H1N1 pandemic virus than any other continent.
Drug Metabolite Patents Prompt Legal Battle
Authors: Marshall Eliot
Published: August 2009

U.S. medical groups are lining up this week against a biotech company in a rare federal court battle over whether a specific drug test can be patented.
Evidence for Vertical Transmission of Bacterial Symbionts from Adult to Embryo in the Caribbean SpongeSvenzea zeai
Authors: Lee On On , Chui Pui Yi , Wong Yue Him , Pawlik Joseph R. , Qian Pei-Yuan
Published: August 2009

The Caribbean reef spongeSvenzea zeaiwas previously found to contain substantial quantities of unicellular photosynthetic and autotrophic microbes in its tissues, but the identities of these symbionts and their method of transfer from adult to progeny are largely unknown. In this study, both a 16S rRNA gene-based fingerprinting technique (denaturing gradient gel electrophoresis [DGGE]) and clone library analysis were applied to compare the bacterial communities associated with adults and embryos ofS. zeaito test the hypothesis of vertical transfer across generations. In addition, the same techniques were applied to the bacterial community from the seawater adjacent to adult sponges to test the hypothesis that water column bacteria could be transferred horizontally as sponge symbionts. Results of both DGGE and clone library analysis support the vertical transfer hypothesis in that the bacterial communities associated with sponge adults and embryos were highly similar to each other but completely different from those in the surrounding seawater. Sequencing of prominent DGGE bands and of clones from the libraries revealed that the bacterial communities associated with the sponge, whether adult or embryo, consisted of a large proportion of bacteria in the phylaChloroflexiandAcidobacteria, while most of the sequences recovered from the community in the adjacent water column belonged to the classAlphaproteobacteria. Altogether, 21 monophyletic sequence clusters, comprising sequences from both sponge adults and embryos but not from the seawater, were identified. More than half of the sponge-derived sequences fell into these clusters. Comparison of sequences recovered in this study with those deposited in GenBank revealed that more than 75% ofS. zeai-derived sequences were closely related to sequences derived from other sponge species, but none of the sequences recovered from the seawater column overlapped with those from adults or embryos ofS. zeai. In conclusion, there is strong evidence that a dominant proportion of sponge-specific bacteria present in the tissues ofS. zeaiare maintained through vertical transfer during embryogenesis rather than through acquisition from the environment (horizontal transfer).
Microbial Biogeography of Six Salt Lakes in Inner Mongolia, China, and a Salt Lake in Argentina
Authors: Pagaling Eulyn , Wang Huanzhi , Venables Madeleine , Wallace Andrew , Grant William D. , Cowan Don A. , Jones Brian E. , Ma Yanhe , Ventosa Antonio , Heaphy Shaun
Published: August 2009

We used cultivation-independent methods to investigate the prokaryotic biogeography of the water column in six salt lakes in Inner Mongolia, China, and a salt lake in Argentina. These lakes had different salt compositions and pH values and were at variable geographic distances, on both local and intercontinental scales, which allowed us to explore the microbial community composition within the context of both contemporary environmental conditions and geographic distance. Fourteen 16S rRNA gene clone libraries were constructed, and over 200 16S rRNA gene sequences were obtained. These sequences were used to construct biotic similarity matrices, which were used in combination with environmental similarity matrices and a distance matrix in the Mantel test to discover which factors significantly influenced biotic similarity. We showed that archaeal biogeography was influenced by contemporary environmental factors alone (Na
+
, CO
3
2−
, and HCO
3
−
ion concentrations; pH; and temperature). Bacterial biogeography was influenced both by contemporary environmental factors (Na
+
, Mg
2+
, and HCO
3
−
ion concentrations and pH) and by geographic distance.
N
-Acetylglucosamine Utilization by
Saccharomyces cerevisiae
Based on Expression of
Candida albicans NAG
Genes
Authors: Wendland Jürgen , Schaub Yvonne , Walther Andrea
Published: August 2009

Synthesis of chitin de novo from glucose involves a linear pathway in
Saccharomyces cerevisiae
. Several of the pathway genes, including
GNA1
, are essential. Genes for chitin catabolism are absent in
S. cerevisiae
. Therefore,
S. cerevisiae
cannot use chitin as a carbon source. Chitin is the second most abundant polysaccharide after cellulose and consists of
N
-acetylglucosamine (GlcNAc) moieties. Here, we have generated
S. cerevisiae
strains that are able to use GlcNAc as a carbon source by expressing four
Candida albicans
genes (
NAG3
or its
NAG4
paralog,
NAG5
,
NAG2
, and
NAG1
) encoding a GlcNAc permease, a GlcNAc kinase, a GlcNAc-6-phosphate deacetylase, and a glucosamine-6-phosphate deaminase, respectively. Expression of
NAG3
and
NAG5
or
NAG4
and
NAG5
in
S. cerevisiae
resulted in strains in which the otherwise-essential Sc
GNA1
could be deleted. These strains required the presence of GlcNAc in the medium, indicating that uptake of GlcNAc and its phosphorylation were achieved. Expression of all four
NAG
genes produced strains that could use GlcNAc as the sole carbon source for growth. Utilization of a GlcNAc catabolic pathway for bioethanol production using these strains was tested. However, fermentation was slow and yielded only minor amounts of ethanol (approximately 3.0 g/liter), suggesting that fructose-6-phosphate produced from GlcNAc under these conditions is largely consumed to maintain cellular functions and promote growth. Our results present the first step toward tapping a novel, renewable carbon source for biofuel production.
Evolution of Diversity in Spatially Structured
Escherichia coli
Populations
Authors: Ponciano José Miguel , La Hyun-Joon , Joyce Paul , Forney Larry J.
Published: August 2009

The stochastic Ricker population model was used to investigate the generation and maintenance of genetic diversity in a bacterial population grown in a spatially structured environment. In particular, we showed that
Escherichia coli
undergoes dramatic genetic diversification when grown as a biofilm. Using a novel biofilm entrapment method, we retrieved 64 clones from each of six different depths of a mature biofilm, and after subculturing for ∼30 generations, we measured their growth kinetics in three different media. We fit a stochastic Ricker population growth model to the recorded growth curves. The growth kinetics of clonal lineages descendant from cells sampled at different biofilm depths varied as a function of both the depth in the biofilm and the growth medium used. We concluded that differences in the growth dynamics of clones were heritable and arose during adaptive evolution under local conditions in a spatially heterogeneous environment. We postulate that under nutrient-limited conditions, selective sweeps would be protracted and would be insufficient to purge less-fit variants, a phenomenon that would allow the coexistence of genetically distinct clones. These findings contribute to the current understanding of biofilm ecology and complement current hypotheses for the maintenance and generation of microbial diversity in spatially structured environments.
DNA-Stable Isotope Probing Integrated with Metagenomics for Retrieval of Biphenyl Dioxygenase Genes from Polychlorinated Biphenyl-Contaminated River Sediment
Authors: Sul Woo Jun , Park Joonhong , Quensen John F. , Rodrigues Jorge L. M. , Seliger Laurie , Tsoi Tamara V. , Zylstra Gerben J. , Tiedje James M.
Published: August 2009

Stable isotope probing with [
13
C]biphenyl was used to explore the genetic properties of indigenous bacteria able to grow on biphenyl in PCB-contaminated River Raisin sediment. A bacterial 16S rRNA gene clone library generated from [
13
C]DNA after a 14-day incubation with [
13
C]biphenyl revealed the dominant organisms to be members of the genera
Achromobacter
and
Pseudomonas
. A library built from PCR amplification of genes for aromatic-ring-hydroxylating dioxygenases from the [
13
C]DNA fraction revealed two sequence groups similar to
bphA
(encoding biphenyl dioxygenase) of
Comamonas testosteroni
strain B-356 and of
Rhodococcus
sp. RHA1. A library of 1,568 cosmid clones was produced from the [
13
C]DNA fraction. A 31.8-kb cosmid clone, detected by aromatic dioxygenase primers, contained genes of biphenyl dioxygenase subunits
bphAE
, while the rest of the clone's sequence was similar to that of an unknown member of the
Gammaproteobacteria
. A discrepancy in G+C content near the
bphAE
genes implies their recent acquisition, possibly by horizontal transfer. The biphenyl dioxygenase from the cosmid clone oxidized biphenyl and unsubstituted and
para
-only-substituted rings of polychlorinated biphenyl (PCB) congeners. A DNA-stable isotope probing-based cosmid library enabled the retrieval of functional genes from an uncultivated organism capable of PCB metabolism and suggest dispersed dioxygenase gene organization in nature.
Biofilm Formation and Cell Surface Properties among Pathogenic and Nonpathogenic Strains of the
Bacillus cereus
Group
Authors: Auger Sandrine , Ramarao Nalini , Faille Christine , Fouet Agnès , Aymerich Stéphane , Gohar Michel
Published: August 2009

Biofilm formation by 102
Bacillus cereus
and
B. thuringiensis
strains was determined. Strains isolated from soil or involved in digestive tract infections were efficient biofilm formers, whereas strains isolated from other diseases were poor biofilm formers. Cell surface hydrophobicity, the presence of an S layer, and adhesion to epithelial cells were also examined.
Identification of
Brevibacteriaceae
by Multilocus Sequence Typing and Comparative Genomic Hybridization Analyses
Authors: Forquin Marie-Pierre , Duvergey Hugo , Proux Caroline , Loux Valentin , Mounier Jerome , Landaud Sophie , Coppée Jean-Yves , Gibrat Jean-François , Bonnarme Pascal , Martin-Verstraete Isabelle , Vallaeys Tatiana
Published: August 2009

Multilocus sequence typing with nine selected genes is shown to be a promising new tool for accurate identifications of
Brevibacteriaceae
at the species level. A developed microarray also allows intraspecific diversity investigations of
Brevibacterium aurantiacum
showing that 13% to 15% of the genes of strain ATCC 9174 were absent or divergent in strain BL2 or ATCC 9175.
Implications of Limits of Detection of Various Methods for
Bacillus anthracis
in Computing Risks to Human Health
Authors: Herzog Amanda B. , McLennan S. Devin , Pandey Alok K. , Gerba Charles P. , Haas Charles N. , Rose Joan B. , Hashsham Syed A.
Published: August 2009

Used for decades for biological warfare,
Bacillus anthracis
(category A agent) has proven to be highly stable and lethal. Quantitative risk assessment modeling requires descriptive statistics of the limit of detection to assist in defining the exposure. Furthermore, the sensitivities of various detection methods in environmental matrices are vital information for first responders. A literature review of peer-reviewed journal articles related to methods for detection of
B. anthracis
was undertaken. Articles focused on the development or evaluation of various detection approaches, such as PCR, real-time PCR, immunoassay, etc. Real-time PCR and PCR were the most sensitive methods for the detection of
B. anthracis
, with median instrument limits of detection of 430 and 440 cells/ml, respectively. There were very few peer-reviewed articles on the detection methods for
B. anthracis
in the environment. The most sensitive limits of detection for the environmental samples were 0.1 CFU/g for soil using PCR-enzyme-linked immunosorbent assay (ELISA), 17 CFU/liter for air using an ELISA-biochip system, 1 CFU/liter for water using cultivation, and 1 CFU/cm
2
for stainless steel fomites using cultivation. An exponential dose-response model for the inhalation of
B. anthracis
estimates of risk at concentrations equal to the environmental limit of detection determined the probability of death if untreated to be as high as 0.520. Though more data on the environmental limit of detection would improve the assumptions made for the risk assessment, this study's quantification of the risk posed by current limitations in the knowledge of detection methods should be considered when employing those methods in environmental monitoring and cleanup strategies.
Improved Detection of F-Specific RNA Coliphages in Fecal Material by Extraction and Polyethylene Glycol Precipitation
Authors: Jones Tineke H. , Johns Michael W.
Published: August 2009

Male-specific RNA coliphages (F-RNA coliphages) have been proposed as a potential viral indicator of fecal contamination in water and foods because they are easy to culture and are a normal component of the mammalian gut flora. F-RNA coliphage plaque numbers are typically obtained by directly plating a 10-fold dilution of 1 g of fecal material, but the numbers of F-RNA coliphages shed by animals and humans may be too low for direct enumeration. Therefore, the sensitivity of detecting F-RNA coliphages in fecal material was improved by extracting and precipitating F-RNA coliphage from a 10-g fecal sample by use of polyethylene glycol (PEG). The highest recovery of F-RNA coliphage with 10% beef extract, pH 7.2, was obtained in the presence of 1 M NaCl and 10% PEG after 16 h of precipitation, but a pellet was not obtained after a short precipitation time of 2 h. There was no significant difference between eluant-to-fecal-material ratios of 4:1 and 9:1 or homogenization with a stomacher or pulsifier. F-RNA coliphage were detected in 64% (16 of 25 samples) of fecal samples from various sources when the sample size was 10 g but in 36% (9 of 25 samples) of samples when the sample size was 1 g. When F-RNA coliphage were detected in 1-g samples, they were also detected in 10-g samples. When F-RNA coliphage were detected in 10-g samples but not in 1-g samples, the levels were <100 PFU/g.
Estimating Risk from Small Inocula by Using Population Growth Parameters
Authors: Malakar P. K. , Barker G. C.
Published: August 2009

Risk from an uncertain small inoculum depends on variability of single-cell lag times. However, quantifying single-cell variability is technically challenging. It is possible to estimate this variability using population growth parameters. We demonstrate this possibility using data from literature and show a Bayesian scheme for performing this task.
Novel and Unique Diagnostic Biomarkers forBacillus anthracisInfection
Authors: Sela-Abramovich Sagit , Chitlaru Theodor , Gat Orit , Grosfeld Haim , Cohen Ofer , Shafferman Avigdor
Published: August 2009

A search for bacterium-specific biomarkers in peripheral blood following infection withBacillus anthraciswas carried out with rabbits, using a battery of specific antibodies generated by DNA vaccination against 10 preselected highly immunogenic bacterial antigens which were identified previously by a genomic/proteomic/serologic screen of theB. anthracissecretome. Detection of infection biomarkers in the circulation of infected rabbits could be achieved only after removal of highly abundant serum proteins by chromatography using a random-ligand affinity column. Besides the toxin component protective antigen, the following three secreted proteins were detected in the circulation of infected animals: the chaperone and protease HtrA (BA3660), an NlpC/P60 endopeptidase (BA1952), and a protein of unknown function harboring two SH3 (Src homology 3) domains (BA0796). The three proteins could be detected in plasma samples from infected animals exhibiting 103to 105CFU/ml blood and also in standard blood cultures at 3 to 6 h post-bacterial inoculation at a bacteremic level as low as 103CFU/ml. Furthermore, the three biomarkers appear to be present only in the secretome ofB. anthracis, not in those of the related pathogensB. thuringiensisandB. cereus. To the best of our knowledge, this is the first report of direct detection ofB. anthracis-specific proteins, other than the toxin components, in the circulation of infected animals.
Antimicrobial Resistance-Conferring Plasmids with Similarity to Virulence Plasmids from Avian Pathogenic
Escherichia coli
Strains in
Salmonella enterica
Serovar Kentucky Isolates from Poultry
Authors: Fricke W. Florian , McDermott Patrick F. , Mammel Mark K. , Zhao Shaohua , Johnson Timothy J. , Rasko David A. , Fedorka-Cray Paula J. , Pedroso Adriana , Whichard Jean M. , LeClerc J. Eugene , White David G. , Cebula Thomas A. , Ravel Jacques
Published: August 2009

Salmonella enterica
, a leading cause of food-borne gastroenteritis worldwide, may be found in any raw food of animal, vegetable, or fruit origin.
Salmonella
serovars differ in distribution, virulence, and host specificity.
S
almonella enterica
serovar Kentucky, though often found in the food supply, is less commonly isolated from ill humans. The multidrug-resistant isolate
S
. Kentucky CVM29188, isolated from a chicken breast sample in 2003, contains three plasmids (146,811 bp, 101,461 bp, and 46,121 bp), two of which carry resistance determinants (pCVM29188_146 [
strAB
and
tetRA
] and pCVM29188_101 [
bla
CMY-2
and
sugE
]). Both resistance plasmids were transferable by conjugation, alone or in combination, to
S.
Kentucky,
S
almonella enterica
serovar Newport, and
E
scherichia coli
recipients. pCVM29188_146 shares a highly conserved plasmid backbone of 106 kb (>90% nucleotide identity) with two virulence plasmids from
a
vian
p
athogenic
E
scherichia c
oli
strains (pAPEC-O1-ColBM and pAPEC-O2-ColV). Shared avian pathogenic
E. coli
(APEC) virulence factors include
iutA iucABCD
,
sitABCD
,
etsABC
,
iss
, and
iroBCDEN.
PCR analyses of recent (1997 to 2005)
S.
Kentucky isolates from food animal, retail meat, and human sources revealed that 172 (60%) contained similar APEC-like plasmid backbones. Notably, though rare in human- and cattle-derived isolates, this plasmid backbone was found at a high frequency (50 to 100%) among
S.
Kentucky isolates from chickens within the same time span. Ninety-four percent of the APEC-positive isolates showed resistance to tetracycline and streptomycin. Together, our findings of a resistance-conferring APEC virulence plasmid in a poultry-derived
S.
Kentucky isolate and of similar resistance/virulence plasmids in most recent
S.
Kentucky isolates from chickens and, to lesser degree, from humans and cattle highlight the need for additional research in order to examine the prevalence and spread of combined virulence and resistance plasmids in bacteria in agricultural, environmental, and clinical settings.
Competition of
Listeria monocytogenes
Serotype 1/2a and 4b Strains in Mixed-Culture Biofilms
Authors: Pan Youwen , Breidt Frederick , Kathariou Sophia
Published: August 2009

The majority of
Listeria monocytogenes
isolates recovered from foods and the environment are strains of serogroup 1/2, especially serotypes 1/2a and 1/2b. However, serotype 4b strains cause the majority of human listeriosis outbreaks. Our investigation of
L. monocytogenes
biofilms used a simulated food-processing system that consisted of repeated cycles of growth, sanitation treatment, and starvation to determine the competitive fitness of strains of serotypes 1/2a and 4b in pure and mixed-culture biofilms. Selective enumeration of strains of a certain serotype in mixed-culture biofilms on stainless steel coupons was accomplished by using serotype-specific quantitative PCR and propidium monoazide treatment to prevent amplification of extracellular DNA or DNA from dead cells. The results showed that the serotype 1/2a strains tested were generally more efficient at forming biofilms and predominated in the mixed-culture biofilms. The growth and survival of strains of one serotype were not inhibited by strains of the other serotype in mixed-culture biofilms. However, we found that a cocktail of serotype 4b strains survived and grew significantly better in mixed-culture biofilms containing a specific strain of serotype 1/2a (strain SK1387), with final cell densities averaging 0.5 log
10
CFU/cm
2
higher than without the serotype 1/2a strain. The methodology used in this study contributed to our understanding of how environmental stresses and microbial competition influence the survival and growth of
L. monocytogenes
in pure and mixed-culture biofilms.
Glyphosate Resistance as a Novel Select-Agent-Compliant, Non-Antibiotic-Selectable Marker in Chromosomal Mutagenesis of the Essential Genes
asd
and
dapB
of
Burkholderia pseudomallei
Authors: Norris Michael H. , Kang Yun , Lu Diana , Wilcox Bruce A. , Hoang Tung T.
Published: August 2009

Genetic manipulation of the category B select agents
Burkholderia pseudomallei
and
Burkholderia mallei
has been stifled due to the lack of compliant selectable markers. Hence, there is a need for additional select-agent-compliant selectable markers. We engineered a selectable marker based on the
gat
gene (encoding glyphosate acetyltransferase), which confers resistance to the common herbicide glyphosate (GS). To show the ability of GS to inhibit bacterial growth, we determined the effective concentrations of GS against
Escherichia coli
and several
Burkholderia
species. Plasmids based on
gat
, flanked by unique flip recombination target (
FRT
) sequences, were constructed for allelic-replacement. Both allelic-replacement approaches, one using the counterselectable marker
pheS
and the
gat-FRT
cassette and one using the DNA incubation method with the
gat-FRT
cassette, were successfully utilized to create deletions in the
asd
and
dapB
genes of wild-type
B. pseudomallei
strains. The
asd
and
dapB
genes encode an aspartate-semialdehyde dehydrogenase (BPSS1704, chromosome 2) and dihydrodipicolinate reductase (BPSL2941, chromosome 1), respectively. Mutants unable to grow on media without diaminopimelate (DAP) and other amino acids of this pathway were PCR verified. These mutants displayed cellular morphologies consistent with the inability to cross-link peptidoglycan in the absence of DAP. The
B. pseudomallei
1026b Δ
asd
::
gat-FRT
mutant was complemented with the
B. pseudomallei asd
gene on a site-specific transposon, mini-Tn
7
-
bar
, by selecting for the
bar
gene (encoding bialaphos/PPT resistance) with PPT. We conclude that the
gat
gene is one of very few appropriate, effective, and beneficial compliant markers available for
Burkholderia
select-agent species. Together with the
bar
gene, the
gat
cassette will facilitate various genetic manipulations of
Burkholderia
select-agent species.
Identification of the Polyhydroxyalkanoate (PHA)-Specific Acetoacetyl Coenzyme A Reductase among Multiple FabG Paralogs in
Haloarcula hispanica
and Reconstruction of the PHA Biosynthetic Pathway in
Haloferax volcanii
Authors: Han Jing , Lu Qiuhe , Zhou Ligang , Liu Hailong , Xiang Hua
Published: August 2009

Genome-wide analysis has revealed abundant FabG (β-ketoacyl-ACP reductase) paralogs, with uncharacterized biological functions, in several halophilic archaea. In this study, we identified for the first time that the
fabG1
gene, but not the other five
fabG
paralogs, encodes the polyhydroxyalkanoate (PHA)-specific acetoacetyl coenzyme A (acetoacetyl-CoA) reductase in
Haloarcula hispanica
. Although all of the paralogous
fabG
genes were actively transcribed, only disruption or knockout of
fabG1
abolished PHA synthesis, and complementation of the Δ
fabG1
mutant with the
fabG1
gene restored both PHA synthesis capability and the NADPH-dependent acetoacetyl-CoA reductase activity. In addition, heterologous coexpression of the PHA synthase genes (
phaEC
) together with
fabG1
, but not its five paralogs, reconstructed the PHA biosynthetic pathway in
Haloferax volcanii
, a PHA-defective haloarchaeon. Taken together, our results indicate that FabG1 in
H. hispanica
, and possibly its counterpart in
Haloarcula marismortui
, has evolved the distinct function of supplying precursors for PHA biosynthesis, like PhaB in bacteria. Hence, we suggest the renaming of FabG1 in both genomes as PhaB, the PHA-specific acetoacetyl-CoA reductase of halophilic archaea.
Genetic Basis for Alkaline Activation of Germination in
Bacillus thuringiensis
subsp.
israelensis
Authors: Abdoarrahem M. M. , Gammon K. , Dancer B. N. , Berry C.
Published: August 2009

Differences in activation between spores from strains of
Bacillus thuringiensis
subsp.
israelensis
with and without the toxin-encoding plasmid pBtoxis are demonstrated. Following alkaline activation, the strain bearing pBtoxis shows a significantly greater germination rate. Expression of just three genes constituting a previously identified, putative
ger
operon from this plasmid is sufficient to produce the same phenotype and characterizes this operon as a genetic determinant of alkaline activation.
Microbial Decomposer Communities Are Mainly Structured by Trophic Status in Circumneutral and Alkaline Streams
Authors: Duarte Sofia , Pascoal Cláudia , Garabétian Frédéric , Cássio Fernanda , Charcosset Jean-Yves
Published: August 2009

In streams, the release of nitrogen and phosphorus is reported to affect microbial communities and the ecological processes they govern. Moreover, the type of inorganic nitrogen (NO3, NO2, or NH4) may differently impact microbial communities. We aimed to identify the environmental factors that structure aquatic microbial communities and drive leaf litter decomposition along a gradient of eutrophication. We selected five circumneutral (Portuguese) and five alkaline (French) streams differing in nutrient concentrations to monitor mass loss of alder leaves, bacterial and fungal diversity by PCR-denaturing gradient gel electrophoresis, fungal biomass and reproduction, and bacterial biomass during 11 weeks of leaf immersion. The concentrations of inorganic nutrients in the stream water ranged from 5 to 300 μg liter−1soluble reactive phosphorus, 0.30 to 5.50 mg liter−1NO3-N, 2 to 103 μg liter−1NO2-N, and <4 to 7,100 μg liter−1NH4-N. Species richness was maximum in moderately anthropized (eutrophic) streams but decreased in the most anthropized (hypertrophic) streams. Different species assemblages were found in subsets of streams with different trophic statuses. In both geographic areas, the limiting nutrient, either nitrate or phosphate, stimulated the microbial activity in streams of intermediate trophic status. In the hypertrophic streams, fungal biomass and reproduction were significantly lower, and bacterial biomass dramatically decreased at the site with the highest ammonium concentration. The limiting nutrients that defined the trophic status were the main factor structuring fungal and bacterial communities, whatever the geographic area. A very high ammonium concentration in stream water most probably has negative impacts on microbial decomposer communities.
The Response ofCampylobacter jejunito Low Temperature Differs from That ofEscherichia coli
Authors: Hughes Rebecca-Ayme , Hallett Kathy , Cogan Tristan , Enser Mike , Humphrey Tom
Published: August 2009

Human infection withCampylobacter jejuniis often associated with the consumption of foods that have been exposed to both chilling and high temperatures. Despite the public health importance of this pathogen, little is known about the effects of cold exposure on its ability to survive a subsequent heat challenge. This work examined the effect of rapid exposure to chilling, as would occur in poultry processing, on the heat resistance at 56°C of twoC. jejunistrains, 11168 and 2097e48, and ofEscherichia coliK-12. UnlikeE. coliK-12, whose cold-exposed cells showed increased sensitivity to 56°C, such exposure had only a marginal effect on subsequent heat resistance inC. jejuni. This may be explained by the finding that during rapid chilling, unlikeE. colicells,C. jejunicells are unable to alter their fatty acid composition and do not adapt to cold exposure. However, their unaltered fatty acid composition is more suited to survival when cells are exposed to high temperatures. This hypothesis is supported by the fact that inC. jejuni, the ratio of unsaturated to saturated fatty acids was not significantly different after cold exposure, but it was inE. coli. The low-temperature response ofC. jejuniis very different from that of other food-borne pathogens, and this may contribute to its tolerance to further heat stresses.
Mobilization of a Tn
402
-Like Class 1 Integron with a Novel Cassette Array via Flanking Miniature Inverted-Repeat Transposable Element-Like Structures
Authors: Gillings Michael R. , Labbate Maurizio , Sajjad Ammara , Giguère Nellie J. , Holley Marita P. , Stokes H. W.
Published: August 2009

A Tn
402
-like class 1 integron was recovered from a prawn-associated bacterium. One of its cassettes included methionine sulfoxide reductase genes, the first example of such genes being captured by an integron. The integron was flanked by direct repeats that resemble miniature inverted-repeat transposable element sequences. Excision of the integron by homologous recombination through these sequences was demonstrated.
Isolation, Diversity, and Antimicrobial Activity of Rare Actinobacteria from Medicinal Plants of Tropical Rain Forests in Xishuangbanna, China
Authors: Qin Sheng , Li Jie , Chen Hua-Hong , Zhao Guo-Zhen , Zhu Wen-Yong , Jiang Cheng-Lin , Xu Li-Hua , Li Wen-Jun
Published: August 2009

Endophytic actinobacteria are relatively unexplored as potential sources of novel species and novel natural products for medical and commercial exploitation. Xishuangbanna is recognized throughout the world for its diverse flora, especially the rain forest plants, many of which have indigenous pharmaceutical histories. However, little is known about the endophytic actinobacteria of this tropical area. In this work, we studied the diversity of actinobacteria isolated from medicinal plants collected from tropical rain forests in Xishuangbanna. By the use of different selective isolation media and methods, a total of 2,174 actinobacteria were isolated. Forty-six isolates were selected on the basis of their morphologies on different media and were further characterized by 16S rRNA gene sequencing. The results showed an unexpected level of diversity, with 32 different genera. To our knowledge, this is the first report describing the isolation of
Saccharopolyspora
,
Dietzia
,
Blastococcus
,
Dactylosporangium
,
Promicromonospora
,
Oerskovia
,
Actinocorallia
, and
Jiangella
species from endophytic environments. At least 19 isolates are considered novel taxa by our current research. In addition, all 46 isolates were tested for antimicrobial activity and were screened for the presence of genes encoding polyketide synthetases and nonribosomal peptide synthetases. The results confirm that the medicinal plants of Xishuangbanna represent an extremely rich reservoir for the isolation of a significant diversity of actinobacteria, including novel species, that are potential sources for the discovery of biologically active compounds.
Novel Clonal Complexes with an Unknown Animal Reservoir Dominate
Campylobacter jejuni
Isolates from River Water in New Zealand
Authors: Carter P. E. , McTavish S. M. , Brooks H. J. L. , Campbell D. , Collins-Emerson J. M. , Midwinter A. C. , French N. P.
Published: August 2009

Campylobacter jejuni
is widely distributed in the environment, and river water has been shown to carry high levels of the organism. In this study, 244
C. jejuni
isolates from three river catchment areas in New Zealand were characterized using multilocus sequence typing. Forty-nine of the 88 sequence types identified were new. The most common sequence types identified were ST-2381 (30 isolates), ST-45 (25 isolates), and ST-1225 (23 isolates). The majority of the sequence types identified in the river water could be attributed to wild bird fecal contamination. Two novel clonal complexes (CC) were identified, namely, CC ST-2381 (11 sequence types, 46 isolates) and CC ST-3640 (6 sequence types, 12 isolates), in which all of the sequence types were new. CC ST-2381 was the largest complex identified among the isolates and was present in two of the three rivers. None of the sequence types associated with the novel complexes has been identified among human isolates. The ST-2381 complex is not related to complexes associated with cattle, sheep, or poultry. The source of the novel complexes has yet to be identified.
Impact of Alginate Overproduction on Attachment and Biofilm Architecture of a Supermucoid
Pseudomonas aeruginosa
Strain
Authors: Hay Iain D. , Gatland Kali , Campisano Andrea , Jordens J. Zoe , Rehm Bernd H. A.
Published: August 2009

The supermucoid
Pseudomonas aeruginosa
strain PDO300Δ
alg8
(pBBR1MCS-5:
alg8
) showed strongly impaired attachment compared with the respective mucoid or nonmucoid strains and formed a thicker biofilm with large extended mushroom-like microcolonies. Alginate lyase treatment dissolved microcolonies. The data suggested that alginate overproduction impairs attachment but plays a structural role in microcolony formation.
Internalization of
Salmonella enterica
in Leaves Is Induced by Light and Involves Chemotaxis and Penetration through Open Stomata
Authors: Kroupitski Yulia , Golberg Dana , Belausov Eduard , Pinto Riky , Swartzberg Dvora , Granot David , Sela Shlomo
Published: August 2009

Outbreaks of salmonellosis related to consumption of fresh produce have raised interest in
Salmonella-
plant interactions leading to plant colonization. Incubation of
gfp
-tagged
Salmonella enterica
with iceberg lettuce leaves in the light resulted in aggregation of bacteria near open stomata and invasion into the inner leaf tissue. In contrast, incubation in the dark resulted in a scattered attachment pattern and very poor stomatal internalization. Forcing stomatal opening in the dark by fusicoccin had no significant effect on
Salmonella
internalization. These results imply that the pathogen is attracted to nutrients produced de novo by photosynthetically active cells. Indeed, mutations affecting
Salmonella
motility and chemotaxis significantly inhibited bacterial internalization. These findings suggest a mechanistic account for entry of
Salmonella
into the plant's apoplast and imply that either
Salmonella
antigens are not well recognized by the stoma-based innate immunity or that this pathogen has evolved means to evade it. Internalization of leaves may provide a partial explanation for the failure of sanitizers to efficiently eradicate food-borne pathogens in leafy greens.
Symbiont Succession during Embryonic Development of the European Medicinal Leech,
Hirudo verbana
Authors: Rio Rita V. M. , Maltz Michele , McCormick Benjamin , Reiss Alexander , Graf Joerg
Published: August 2009

The European medicinal leech,
Hirudo verbana
, harbors simple microbial communities in the digestive tract and bladder. The colonization history, infection frequency, and growth dynamics of symbionts through host embryogenesis are described using diagnostic PCR and quantitative PCR. Symbiont species displayed diversity in temporal establishment and proliferation through leech development.