bluuebunny/crossref_metadata_2025 huggingface dataset:
Sexual Knowledge, Attitudes, and Risk Behaviors of Students in Turkey
Authors: Gökengin Deniz , Yamazhan Tansu , Özkaya Deniz , Aytuǧ Sebnem , Ertem Ekin , Arda Bilgin , Serter Demir
Published: October 2009

ABSTRACT: This survey produced baseline information about student knowledge of sexually transmitted diseases (STDs), their sexual attitudes, and their behavior to help establish control and education programs. The study was conducted at Ege University, Izmir, Turkey, during the 1999–2000 academic year. A total of 2,217 first‐ and fourth‐year students determined by stratified sampling constituted the study group. All students who volunteered to participate completed a questionnaire assessing sociodemographic and knowledge factors, sexual attitudes, behavior, and history of STDs. The rate of students having had sexual experience was 36.6%. Males were more sexually active than females. Most students (71.4%) began sexual activity at ages 15–19 without any difference by gender. Males reported significantly more sexual partners than females. Similarly, the rate of male students never using condoms was significantly higher than females. Condom was the most frequent contraception method, followed by oral contraceptives and withdrawal. Mean score on the knowledge questions was 16.29 (highest score 30). The most widely known STD was HIV infection and AIDS. Students' knowledge of transmission routes, signs and symptoms, and risk groups of STDs was insufficient. Main sources of knowledge were visual and print media, and friends. Most students (84.7%) viewed prevention from STDs as a person's own responsibility. Young people in Turkey are sexually active and tend to engage in high‐risk behavior. However, their knowledge on sexual health and sexually transmitted diseases is insufficient. Study results suggest a need for implementation of STD control programs and provision of school sexuality education for adolescents and young adults.
Community Needs and Strengths Assessments as an Active Learning Project
Authors: Misra Ranjita , Ballard Danny
Published: October 2009

ABSTRACT: The Community Needs and Strengths Assessment Project (CNSAP) incorporated development of needs and strengths assessment research into an undergraduate Community Health course as an active learning project — one of seven principles for effective practice in undergraduate education. Community needs and strengths assessments prove useful to health educators primarily in planning programs and promoting effective public relations. Assessments also help to identify and diagnose health problems and to evaluate programs. Through the CNSAP students completed a process health educators use to identify gaps between current and required programs and to prioritize assets and resources based on community needs and strengths. The CNSAP focused on mastery of four skills required for completing a needs and strengths assessment: identifying data sources, conducting primary data collection from a target audience, analyzing data and prioritizing identified needs and strengths, and abstracting information concisely. The project, which included substantial community involvement, helped students identify needs and strengths necessary for addressing community health problems and concerns.
Using Polvika's Model to Create a Service‐Learning Partnership
Authors: Foss Gwendolyn F. , Bonaiuto Maria M. , Johnson Z. Sue , Moreland Dee M.
Published: October 2009

ABSTRACT: Collaboration can maximize limited resources of universities, school systems, and public health departments by offering learning from experience. Polvika: s theoretical model and principles from Community‐Campus Partnerships for Health guided development of a service‐learning partnership among a university, a county health department, and an alternative school in a large public school district. Of three commonly identified patterns of service‐learning, this partnership demonstrated the pattern that equally emphasizes service to a community or agency, and mutual learning by all participants. All organizations in the partnership share a common goal to optimize the health of children in schools, and to provide quality learning for professional students. The partnership is in its fourth year. Formal interagency agreements now exist among all partners. Individuals continue to demonstrate flexibility and mutual awareness of strengths and limitations of respective organizations. Public school students receive more services, many high‐risk children achieve better learning outcomes, school nurses offer expanded services in many schools with the help of nursing students, and undergraduate and graduate nursing students gain meaningful learning experiences. Some nursing students state that school nursing has become a career goal. The partnership continues to evolve to meet changing needs of the partners. Members remain satisfied with the collaboration.
Impact of Promoting Lifestyle Activity for Youth (PLAY) on Children's Physical Activity
Authors: Pangrazi Robert P. , Beighle Aaron , Vehige Tammy , Vack Carol
Published: October 2009

ABSTRACT: This study examined effects of a school‐based intervention called PLAY (Promoting Lifestyle Activity for Youth) on physical activity levels and body mass index (BMI) of students. Participants included 606 fourth‐grade students selected from a stratified sample of 35 schools in Arizona and placed into four groups: PLAY & PE, PLAY Only, PE Only, and No Treatment. A treatment‐control, post‐measurement design assessed physical activity using the YAMAX pedometer, and height and weight data were collected following the intervention. One‐way ANOVAs were used to analyze the data. Results indicated the treatment was effective at increasing the physical activity level of children, especially girls. No significant differences between groups were found for BMI. Programs such as PLAY, which can increase the activity level of children, may have significant health implications for youth.
Assessing Prevalence of Overweight and Obesity Through Self‐Reports of Height and Weight by High School Students in Taipei, Taiwan
Authors: Page Randy M. , Lee Ching‐Mei , Miao Nae‐Fang
Published: October 2009

ABSTRACT: This study compared consistency of age‐ and gender‐specific self‐reported height and weight and calculated body mass index among a sample of high school students in Taipei County, Taiwan to reference values for Taiwanese school‐aged youth obtained through national studies. Taipei high school students provided self‐reports of height and weight that were similar to national reference values. Use of self‐reported height and weight in this sample appeared warranted and may reliably be used to calculate aggregate indices of body mass, overweight, and obesity. This study compared prevalence of overweight and obesity in the current sample with other adolescent populations using international criteria (International TaskForce on Obesity). Using these criteria, 17.6% of boys and 9.4% of girls met the definition of overweight and 3.7% of boys and 1.6% of girls met the definition of obesity. While use of self‐reported height and weight appears justified in this sample, researchers should not assume self‐report measures will always be accurate. Researchers considering use of self‐reported height and weight should compare their results to normative reference values when possible to increase confidence in using self‐report measures of height and weight.
School‐Based Health Centers and Academic Performance: Research, Challenges, and Recommendations
Authors: Geierstanger Sara Peterson , Amaral Gorette , Mansour Mona , Walters Susan Russell
Published: October 2009

ABSTRACT: School‐based health centers (SBHCs) provide physical and mental health services on school campuses to improve student health status, and thereby potentially facilitate student academic success. With a growing emphasis on school accountability and the simultaneous dwindling of resources at the federal, state, and local levels, SBHCs face increasing pressures from school administrators and funders to document their impact on student academic achievement. This article reviews the methods, findings, and limitations of studies that have examined the relationship between SBHCs and academic performance. It also describes methodological challenges of conducting and interpreting such research, and discusses factors and intermediate variables that influence student academic performance. Recommendations are offered for SBHC researchers, evaluators, and service providers in response to the pressure they are facing to document the effect of SBHC services on academic outcomes. (J Sch Health. 2004;74(9):347–352)
Implementing Evidence‐Based Substance Use Prevention Curricula in North Carolina Public School Districts
Authors: Pankratz Melinda M. , Hallfors Denise D.
Published: October 2009

ABSTRACT: The Safe and Drug‐Free Schools and Communities Act (SDFSCA) provides funding for prevention education to nearly every school district in the nation. Recent federal policy requires SDFSCA recipients to implement evidence‐based prevention programs. This paper reports the extent to which North Carolina public school districts implement evidence‐based substance use prevention curricula. Results showed that while the majority of school districts use evidence‐based prevention curricula, they are rarely the most commonly used curricula. Evidence‐based curricula are much more likely to be used at the middle school level than at the elementary or high school levels. Urbanicity, coordinator time, and coordinator experience correlated with extensive use of evidence‐based curricula in the bivariate analysis, but only time spent on prevention by the Safe and Drug‐Free Schools (SDFS) coordinator significantly predicted extensive use in the multivariate analysis. Increasing district SDFSCA coordinator time is a necessary step for diffusing evidence‐based curricula. (J Sch Health. 2004;74(9):353–358)
Reliability and Validity of a Brief Questionnaire to Assess Television Viewing and Computer Use by Middle School Children
Authors: Schmitz Kathryn H. , Harnack Lisa , Fulton Janet E. , Jacobs David R. , Gao Shujun , Lytle Leslie A. , Van Coevering Pam
Published: October 2009

ABSTRACT: Sedentary behaviors, like television viewing, are positively associated with overweight among young people. To monitor national health objectives for sedentary behaviors in young adolescents, this project developed and assessed the reliability and validity of a brief questionnaire to measure weekly television viewing, usual television viewing, and computer use by middle school children. Reliability and validity of the Youth Risk Behavior Survey (YRBS) question on weekday television viewing also were examined. A brief, five‐item television and computer use questionnaire was completed twice by 245 middle school children with one week apart. To concurrently assess validity, students also completed television and computer use logs for seven days. Among all students, Spearman correlations for test‐retest reliability for television viewing and computer use ranged from 0.55 to 0.68. Spearman correlations between the first questionnaire and the seven‐day log produced the following results: YRBS question for weekday television viewing (0.46), weekend television viewing (0.37), average television viewing over the week (0.47), and computer use (0.39). Methods comparison analysis showed a mean difference (hours/week) between answers to questionnaire items and the log of −0.04 (1.70 standard deviation [SD]) hours for weekday television, −0.21 (2.54 SD) for weekend television, −0.09 (1.75 SD) for average television over the week, and 0.68 (1.26 SD) for computer use. The YRBS weekday television viewing question, and the newly developed questions to assess weekend television viewing, average television viewing, and computer use, produced adequate reliability and validity for surveillance of middle school students. (J Sch Health. 2004;74(9):370–377)
Preconcentration/Separation of Gold and Palladium by a Microcolumn Packed with Azadirachta Indica Leaf Powder and Their Determination in Geological Samples by ICP‐OES
Authors: Jibrin Sabo Suleiman , Huang Chaozhang , Li Jia , Zhang Nan , Hu Bin
Published: October 2009

A new method using a microcolumn (20 mm length × 2.0 mm i.d.) packed with Azadirachta Indica leaf powder (Neem leaf) as an adsorbent for the preconcentration/separation of Au and Pd prior to their determination by ICP‐OES in geological samples is presented. Various factors affecting the separation and preconcentration of the target analytes such as pH, sample flow rate and volume, eluent concentration and volume and interfering ions were studied and the optimal experimental conditions were established. The adsorption capacity of Azadirachta Indica leaf for Au and Pd was found to be 39.2 and 9.8 mg g−1, respectively. The detection limits (3s) of this method for Au and Pd with an enrichment factor of 50 were 47 ng l−1 and 59 ng l−1 and the relative standard deviations were 4.8% and 5.7% (n = 7, adsorption capacity C = 5 ng ml−1), respectively. In order to validate the proposed method, the certified reference material, GBW07293, was analysed, and a good agreement was obtained between the certified and determined values.
Flood damage reduction by compartmentalization of a dike ring: comparing the effectiveness of three strategies
Authors: Oost J. , Hoekstra A.Y.
Published: October 2009

Compartmentalization of dike ring areas is currently seen as one of the promising options for managing or reducing the risk of flooding. Recently, several studies on the effectiveness of subdividing dike ring areas by means of compartmentalization dikes were published. These studies show that the total damage after a flood could indeed be smaller, but that the damage could also turn out to be larger on a local level. The available studies on compartmentalization usually consider only one dike pattern in the area concerned. This article develops, assesses and compares three fundamentally different strategies, based on different configurations of the compartmentalization dikes. Not only do we examine the effects of the most probable flood scenarios, we also look at the worst‐case scenario, whereby the water is able to flood into the dike ring area from all sides. The spatial layout of the area codetermines the effectiveness of each strategy. Dike ring area 14, which lies in the west of the Netherlands and that covers some cities, like Amsterdam, Rotterdam and The Hague, was chosen as the area of application. The results show that for this dike ring, the secondary dike strategy is most effective in reducing the number of expected victims under different flood scenarios.
Carbon sequestration under Miscanthus: a study of 13C distribution in soil aggregates
Authors: DONDINI MARTA , VAN GROENIGEN KEES‐JAN , DEL GALDO ILARIA , JONES MICHAEL B.
Published: October 2009

The growing of bioenergy crops has been widely suggested as a key strategy in mitigating anthropogenic CO2 emissions. However, the full mitigation potential of these crops cannot be assessed without taking into account their effect on soil carbon (C) dynamics. Therefore, we analyzed the C dynamics through four soil depths under a 14‐year‐old Miscanthus plantation, established on former arable land. An adjacent arable field was used as a reference site. Combining soil organic matter (SOM) fractionation with 13C natural abundance analyses, we were able to trace the fate of Miscanthus‐derived C in various physically protected soil fractions. Integrated through the whole soil profile, the total amount of soil organic carbon (SOC) was higher under Miscanthus than under arable crop, this difference was largely due to the input of new C. The C stock of the macroaggregates (M) under Miscanthus was significantly higher than those in the arable land. Additionally, the C content of the micro‐within macroaggregates (mM) were higher in the Miscanthus soil as compared with the arable soil. Analysis of the intramicroaggregates particulate organic matter (POM) suggested that the increase C storage in mM under Miscanthus was caused by a decrease in disturbance of M. Thus, the difference in C content between the two land use systems is largely caused by soil C storage in physically protected SOM fractions. We conclude that when Miscanthus is planted on former arable land, the resulting increase in soil C storage contributes considerably to its CO2 mitigation potential.
Is oxidative stress a cause or consequence of disuse muscle atrophy in mice? A proteomic approach in hindlimb‐unloaded mice
Authors: Brocca Lorenza , Pellegrino Maria Antonietta , Desaphy Jean‐François , Pierno Sabata , Camerino Diana Conte , Bottinelli Roberto
Published: October 2009

Two‐dimensional proteomic maps of soleus (Sol), a slow oxidative muscle, and gastrocnemius (Gas), a fast glycolytic muscle of control mice (CTRL), of mice hindlimb unloaded for 14 days (HU mice) and of HU mice treated with trolox (HU‐TRO), a selective and potent antioxidant, were compared. The proteomic analysis identified a large number of differentially expressed proteins in a pool of ∼800 proteins in both muscles. The protein pattern of Sol and Gas adapted very differently to hindlimb unloading. The most interesting adaptations related to the cellular defense systems against oxidative stress and energy metabolism. In HU Sol, the antioxidant defense systems and heat shock proteins were downregulated, and protein oxidation index and lipid peroxidation were higher compared with CTRL Sol. In contrast, in HU Gas the antioxidant defense systems were upregulated, and protein oxidation index and lipid peroxidation were normal. Notably, both Sol and Gas muscles and their muscle fibres were atrophic. Antioxidant administration prevented the impairment of the antioxidant defense systems in Sol and further enhanced them in Gas. Accordingly, it restored normal levels of protein oxidation and lipid peroxidation in Sol. However, muscle and muscle fibre atrophy was not prevented either in Sol or in Gas. A general downsizing of all energy production systems in Sol and a shift towards glycolytic metabolism in Gas were observed. Trolox administration did not prevent metabolic adaptations in either Sol or Gas. The present findings suggest that oxidative stress is not a major determinant of muscle atrophy in HU mice.
Endosymbiotic Bacteria in the Parasitic Ciliate
Ichthyophthirius multifiliis
Authors: Sun H. Y. , Noe J. , Barber J. , Coyne R. S. , Cassidy-Hanley D. , Clark T. G. , Findly R. C. , Dickerson H. W.
Published: October 2009

Endosymbiotic bacteria were identified in the parasitic ciliate
Ichthyophthirius multifiliis
, a common pathogen of freshwater fish. PCR amplification of DNA prepared from two isolates of
I. multifiliis
, using primers that bind conserved sequences in bacterial 16S rRNA genes, generated an ∼1,460-bp DNA product, which was cloned and sequenced. Sequence analysis demonstrated that 16S rRNA gene sequences from three classes of bacteria were present in the PCR product. These included
Alphaproteobacteria
(
Rickettsiales
),
Sphingobacteria
, and
Flavobacterium columnare
. DAPI (4′,6-diamidino-2-phenylindole) staining showed endosymbionts dispersed throughout the cytoplasm of trophonts and, in most, but not all theronts. Endosymbionts were observed by transmission electron microscopy in the cytoplasm, surrounded by a prominent, electron-translucent halo characteristic of
Rickettsia
. Fluorescence in situ hybridization demonstrated that bacteria from the
Rickettsiales
and
Sphingobacteriales
classes are endosymbionts of
I. multifiliis
, found in the cytoplasm, but not in the macronucleus or micronucleus. In contrast,
F. columnare
was not detected by fluorescence in situ hybridization. It likely adheres to
I. multifiliis
through association with cilia. The role that endosymbiotic bacteria play in the life history of
I. multifiliis
is not known.
Oligomerization of Cry11Aa from
Bacillus thuringiensis
Has an Important Role in Toxicity against
Aedes aegypti
Authors: Muñoz-Garay Carlos , Rodríguez-Almazán Claudia , Aguilar Jose N. , Portugal Leivi , Gómez Isabel , Saab-Rincon Gloria , Soberón Mario , Bravo Alejandra
Published: October 2009

Cry11Aa and Cyt1Aa of
Bacillus thuringiensis
are active against mosquitoes and show synergism. Cyt1Aa functions as a membrane receptor inducing Cry11Aa oligomerization. Here we characterized Cry11Aa helix α-3 mutants impaired in oligomerization and toxicity against
Aedes aegypti
, indicating that oligomerization of Cry11Aa is important for toxin action. Cyt1Aa did not recover the insecticidal activity of Cry11Aa mutants.
Pathogenicity of Life-Shortening
Wolbachia
in
Aedes albopictus
after Transfer from
Drosophila melanogaster
Authors: Suh Eunho , Mercer David R. , Fu Yuqing , Dobson Stephen L.
Published: October 2009

Maternally inherited
Wolbachia
bacteria have evolved mechanisms to manipulate the reproduction of their invertebrate hosts, promoting infection spread. A high fitness cost to the host is maladaptive for obligate endosymbionts, and prior studies show rapid selection of new
Wolbachia
associations toward commensal or mutualistic symbioses. Here,
w
MelPop
Wolbachia
is transferred from
Drosophila melanogaster
into the mosquito
Aedes albopictus
. Characterization of the resulting strain provides an extreme example of
Wolbachia
as a pathogen. In addition to reduced longevity and fecundity, abnormally high
Wolbachia
density is associated with embryonic mortality that masks the typical pattern of cytoplasmic incompatibility. The results are consistent with earlier reports that show unpredictable shifts in the
Wolbachia
phenotype after interspecific transfer, which can complicate proposed strategies to modify the age structure of medically important vector populations.
Cryptosporidium
spp. in Wild, Laboratory, and Pet Rodents in China: Prevalence and Molecular Characterization
Authors: Lv Chaochao , Zhang Longxian , Wang Rongjun , Jian Fuchun , Zhang Sumei , Ning Changshen , Wang Helei , Feng Chao , Wang Xinwei , Ren Xupeng , Qi Meng , Xiao Lihua
Published: October 2009

To understand the prevalence of
Cryptosporidium
infection in rodents in China and to assess the potential role of rodents as a source for human cryptosporidiosis, 723 specimens from 18 rodent species were collected from four provinces of China and examined between August 2007 and December 2008 by microscopy after using Sheather's sugar flotation and modified acid-fast staining.
Cryptosporidium
oocysts were detected in 83 specimens, with an overall prevalence of 11.5%.
Phodopus sungorus
,
Phodopus campbelli
, and
Rattus tanezumi
were new reported hosts of
Cryptosporidium
. The genotypes and subtypes of
Cryptosporidium
strains in microscopy-positive specimens were further identified by PCR and sequence analysis of the small subunit rRNA and the 60-kDa glycoprotein (gp60) genes. In addition to
Cryptosporidium parvum
,
C. muris
,
C. andersoni
,
C. wrairi
, ferret genotype, and mouse genotype I, four new
Cryptosporidium
genotypes were identified, including the hamster genotype, chipmunk genotype III, and rat genotypes II and III. Mixed
Cryptosporidium
species/genotypes were found in 10.8% of
Cryptosporidium
-positive specimens. Sequence analysis of the gp60 gene showed that
C. parvum
strains in pet Siberian chipmunks and hamsters were all of the subtype IIdA15G1, which was found previously in a human isolate in The Netherlands and lambs in Spain. The gp60 sequences of
C. wrairi
and the
Cryptosporidium
ferret genotype and mouse genotype I were also obtained. These findings suggest that pet rodents may be potential reservoirs of zoonotic
Cryptosporidium
species and subtypes.
Assessment of Dust Sampling Methods for the Study of Cultivable-Microorganism Exposure in Stables
Authors: Normand Anne-Cécile , Vacheyrou Mallory , Sudre Bertrand , Heederik Dick J. J. , Piarroux Renaud
Published: October 2009

Studies have shown a link between living on a farm, exposure to microbial components (e.g., endotoxins or β-
d
-glucans), and a lower risk for allergic diseases and asthma. Due to the lack of validated sampling methods, studies of asthma and atopy have not relied on exposure assessment based on culture techniques. Our objective was therefore to compare several dust sampling methods for the detection of cultivable-microorganism exposure in stables. Sixteen French farms were sampled using four different methods: (i) active air sampling using a pump, (ii) passive dust sampling with a plastic box, (iii) dust sampling with an electrostatic dust fall collector (wipe), and (iv) dust sampling using a spatula to collect dust already settled on a windowsill. The results showed that collection of settled dust samples with either plastic boxes or wipes was reproducible (pairwise correlations, 0.72 and 0.73, respectively) and resulted in highly correlated results (pairwise correlation between the two methods, 0.82). We also found that settled dust samples collected with a plastic box correctly reflected the composition of the samples collected in the air of the stable when there was no farmer activity. A loss of microbial diversity was observed when dust was kept for 3 months at room temperature. We therefore conclude that measurement of viable microorganisms within a reasonable time frame gives an accurate representation of the microbial composition of stable air.
Rehosting of Bacterial Chaperones for High-Quality Protein Production
Authors: Martínez-Alonso Mónica , Toledo-Rubio Verónica , Noad Rob , Unzueta Ugutz , Ferrer-Miralles Neus , Roy Polly , Villaverde Antonio
Published: October 2009

Coproduction of DnaK/DnaJ inEscherichia colienhances solubility but promotes proteolytic degradation of their substrates, minimizing the yield of unstable polypeptides. Higher eukaryotes have orthologs of DnaK/DnaJ but lack the linked bacterial proteolytic system. By coexpression of DnaK and DnaJ in insect cells with inherently misfolding-prone recombinant proteins, we demonstrate simultaneous improvement of soluble protein yield and quality and proteolytic stability. Thus, undesired side effects of bacterial folding modulators can be avoided by appropriate rehosting in heterologous cell expression systems.
Improved Production of Homo-
d
-Lactic Acid via Xylose Fermentation by Introduction of Xylose Assimilation Genes and Redirection of the Phosphoketolase Pathway to the Pentose Phosphate Pathway in
l
-Lactate Dehydrogenase Gene-Deficient
Lactobacillus plantarum
Authors: Okano Kenji , Yoshida Shogo , Yamada Ryosuke , Tanaka Tsutomu , Ogino Chiaki , Fukuda Hideki , Kondo Akihiko
Published: October 2009

The production of optically pure
d
-lactic acid via xylose fermentation was achieved by using a
Lactobacillus plantarum
NCIMB 8826 strain whose
l
-lactate dehydrogenase gene was deficient and whose phosphoketolase genes were replaced with a heterologous transketolase gene. After 60 h of fermentation, 41.2 g/liter of
d
-lactic acid was produced from 50 g/liter of xylose.
Francisella tularensisType A Strains Cause the Rapid Encystment ofAcanthamoeba castellaniiand Survive in Amoebal Cysts for Three Weeks Postinfection
Authors: El-Etr Sahar H. , Margolis Jeffrey J. , Monack Denise , Robison Richard A. , Cohen Marissa , Moore Emily , Rasley Amy
Published: October 2009

Francisella tularensis, the causative agent of the zoonotic disease tularemia, has recently gained increased attention due to the emergence of tularemia in geographical areas where the disease has been previously unknown and to the organism's potential as a bioterrorism agent. AlthoughF. tularensishas an extremely broad host range, the bacterial reservoir in nature has not been conclusively identified. In this study, the ability of virulentF. tularensisstrains to survive and replicate in the amoebaAcanthamoeba castellaniiwas explored. We observe thatA. castellaniitrophozoites rapidly encyst in response toF. tularensisinfection and that this rapid encystment phenotype is caused by factor(s) secreted by amoebae and/orF. tularensisinto the coculture medium. Further, our results indicate that in contrast to the live vaccine strain LVS, virulent strains ofF. tularensiscan survive inA. castellaniicysts for at least 3 weeks postinfection and that the induction of rapid amoeba encystment is essential for survival. In addition, our data indicate that pathogenicF. tularensisstrains block lysosomal fusion inA. castellanii. Taken together, these data suggest that interactions betweenF. tularensisstrains and amoebae may play a role in the environmental persistence ofF. tularensis.
Metabolic Engineering of the Tricarboxylic Acid Cycle for Improved Lysine Production by
Corynebacterium glutamicum
Authors: Becker Judith , Klopprogge Corinna , Schröder Hartwig , Wittmann Christoph
Published: October 2009

In the present work, lysine production by
Corynebacterium glutamicum
was improved by metabolic engineering of the tricarboxylic acid (TCA) cycle. The 70% decreased activity of isocitrate dehydrogenase, achieved by start codon exchange, resulted in a >40% improved lysine production. By flux analysis, this could be correlated to a flux shift from the TCA cycle toward anaplerotic carboxylation.
Carbohydrate Utilization Patterns for the Extremely Thermophilic Bacterium
Caldicellulosiruptor saccharolyticus
Reveal Broad Growth Substrate Preferences
Authors: VanFossen Amy L. , Verhaart Marcel R. A. , Kengen Servé M. W. , Kelly Robert M.
Published: October 2009

Coutilization of hexoses and pentoses derived from lignocellulose is an attractive trait in microorganisms considered for consolidated biomass processing to biofuels. This issue was examined for the H
2
-producing, extremely thermophilic bacterium
Caldicellulosiruptor saccharolyticus
growing on individual monosaccharides (arabinose, fructose, galactose, glucose, mannose, and xylose), mixtures of these sugars, as well as on xylan and xylogluco-oligosacchrides.
C. saccharolyticus
grew at approximately the same rate (
t
d
, ∼95 min) and to the same final cell density (1 × 10
8
to 3 × 10
8
cells/ml) on all sugars and sugar mixtures tested. In the monosaccharide mixture, although simultaneous consumption of all monosaccharides was observed, not all were utilized to the same extent (fructose > xylose/arabinose > mannose/glucose/galactose). Transcriptome contrasts for monosaccharide growth revealed minimal changes in some cases (e.g., 32 open reading frames [ORFs] changed ≥2-fold for glucose versus galactose), while substantial changes occurred for cases involving mannose (e.g., 353 ORFs changed ≥2-fold for glucose versus mannose). Evidence for catabolite repression was not noted for either growth on multisugar mixtures or the corresponding transcriptomes. Based on the whole-genome transcriptional response analysis and comparative genomics, carbohydrate specificities for transport systems could be proposed for most of the 24 putative carbohydrate ATP-binding cassette transporters and single phosphotransferase system identified in
C. saccharolyticus
. Although most transporter genes responded to individual monosaccharides and polysaccharides, the genes Csac_0692 to Csac_0694 were upregulated only in the monosaccharide mixture. The results presented here affirm the broad growth substrate preferences of
C. saccharolyticus
on carbohydrates representative of lignocellulosic biomass and suggest that this bacterium holds promise for biofuel applications.
Heterologous Expression Studies of
Saccharomyces cerevisiae
Reveal Two Distinct Trypanosomatid CaaX Protease Activities and Identify Their Potential Targets
Authors: Mokry David Z. , Manandhar Surya P. , Chicola Kristen A. , Santangelo George M. , Schmidt Walter K.
Published: October 2009

The CaaX tetrapeptide motif typically directs three sequential posttranslational modifications, namely, isoprenylation, proteolysis, and carboxyl methylation. In all eukaryotic systems evaluated to date, two CaaX proteases (Rce1 and Ste24/Afc1) have been identified. Although the
Trypanosoma brucei
genome also encodes two putative CaaX proteases, the lack of detectable
T. brucei
Ste24 activity in trypanosome cell extracts has suggested that CaaX proteolytic activity within this organism is solely attributed to
T. brucei
Rce1 (J. R. Gillespie et al., Mol. Biochem. Parasitol. 153:115-124. 2007). In this study, we demonstrate that both
T. brucei
Rce1 and
T. brucei
Ste24 are enzymatically active when heterologously expressed in yeast. Using
a
-factor and GTPase reporters, we demonstrate that
T. brucei
Rce1 and
T. brucei
Ste24 possess partially overlapping specificities much like, but not identical to, their fungal and human counterparts. Of interest, a CaaX motif found on a trypanosomal Hsp40 protein was not cleaved by either
T. brucei
CaaX protease when examined in the context of the yeast
a
-factor reporter but was cleaved by both in the context of the Hsp40 protein itself when evaluated using an in vitro radiolabeling assay. We further demonstrate that
T. brucei
Rce1 is sensitive to small molecules previously identified as inhibitors of the yeast and human CaaX proteases and that a subset of these compounds disrupt
T. brucei
Rce1-dependent localization of our GTPase reporter in yeast. Together, our results suggest the conserved presence of two CaaX proteases in trypanosomatids, identify an Hsp40 protein as a substrate of both
T. brucei
CaaX proteases, support the potential use of small molecule CaaX protease inhibitors as tools for cell biological studies on the trafficking of CaaX proteins, and provide evidence that protein context influences
T. brucei
CaaX protease specificity.
Novel Putative Glycosylphosphatidylinositol-Anchored Micronemal Antigen of
Plasmodium falciparum
That Binds to Erythrocytes
Authors: Hinds Louise , Green Judith L. , Knuepfer Ellen , Grainger Munira , Holder Anthony A.
Published: October 2009

We have identified a new
Plasmodium falciparum
erythrocyte binding protein that appears to be located in the micronemes of the merozoite stage of the parasite and membrane linked through a glycosylphosphatidylinositol (GPI) anchor. The protein is designated GPI-anchored micronemal antigen (GAMA) and was identified by applying a set of selection criteria to identify previously uncharacterized merozoite proteins that may have a role in cell invasion. The protein is also present in the proteomes of the sporozoite and ookinete micronemes and is conserved throughout the genus. GAMA contains a novel domain that may be constrained by disulfide bonds and a predicted C-terminal hydrophobic sequence that is presumably replaced by the GPI. The protein is synthesized late during schizogony, processed into two fragments that are linked by a disulfide bond, and translocated to an apical location, which is probably the micronemes. In a proportion of free merozoites GAMA can also be detected on the parasite surface. Following erythrocyte invasion the bulk of the protein is shed in a soluble form, although a short C-terminal fragment may be carried into the newly invaded red blood cell. The protein was shown to bind reversibly to erythrocytes and therefore represents a new example of a host cell binding protein.
Solution Structure, Determined by Nuclear Magnetic Resonance, of the b30-82 Domain of Subunit
b
of
Escherichia coli
F
1
F
o
ATP Synthase
Authors: Priya Ragunathan , Biuković Goran , Gayen Shovanlal , Vivekanandan Subramanian , Grüber Gerhard
Published: October 2009

Subunit
b
, the peripheral stalk of bacterial F
1
F
o
ATP synthases, is composed of a membrane-spanning and a soluble part. The soluble part is divided into tether, dimerization, and δ-binding domains. The first solution structure of b30-82, including the tether region and part of the dimerization domain, has been solved by nuclear magnetic resonance, revealing an α-helix between residues 39 and 72. In the solution structure, b30-82 has a length of 48.07 Å. The surface charge distribution of b30-82 shows one side with a hydrophobic surface pattern, formed by alanine residues. Alanine residues 61, 68, 70, and 72 were replaced by single cysteines in the soluble part of subunit
b
, b22-156. The cysteines at positions 61, 68, and 72 showed disulfide formation. In contrast, no cross-link could be formed for the A70C mutant. The patterns of disulfide bonding, together with the circular dichroism spectroscopy data, are indicative of an adjacent arrangement of residues 61, 68, and 72 in both α-helices in b22-156.
Crystal Structure of Adenylylsulfate Reductase fromDesulfovibrio gigasSuggests a Potential Self-Regulation Mechanism Involving the C Terminus of the β-Subunit
Authors: Chiang Yuan-Lan , Hsieh Yin-Cheng , Fang Jou-Yin , Liu En-Hong , Huang Yen-Chieh , Chuankhayan Phimonphan , Jeyakanthan Jeyaraman , Liu Ming-Yih , Chan Sunney I. , Chen Chun-Jung
Published: October 2009

Adenylylsulfate reductase (adenosine 5′-phosphosulfate [APS] reductase [APSR]) plays a key role in catalyzing APS to sulfite in dissimilatory sulfate reduction. Here, we report the crystal structure of APSR fromDesulfovibrio gigasat 3.1-Å resolution. Different from the α2β2-heterotetramer of theArchaeoglobus fulgidus, the overall structure of APSR fromD. gigascomprises six αβ-heterodimers that form a hexameric structure. The flavin adenine dinucleotide is noncovalently attached to the α-subunit, and two [4Fe-4S] clusters are enveloped by cluster-binding motifs. The substrate-binding channel inD. gigasis wider than that inA. fulgidusbecause of shifts in the loop (amino acid 326 to 332) and the α-helix (amino acid 289 to 299) in the α-subunit. The positively charged residue Arg160 in the structure ofD. gigaslikely replaces the role of Arg83 in that ofA. fulgidusfor the recognition of substrates. The C-terminal segment of the β-subunit wraps around the α-subunit to form a functional unit, with the C-terminal loop inserted into the active-site channel of the α-subunit from another αβ-heterodimer. Electrostatic interactions between the substrate-binding residue Arg282 in the α-subunit and Asp159 in the C terminus of the β-subunit affect the binding of the substrate. Alignment of APSR sequences fromD. gigasandA. fulgidusshows the largest differences toward the C termini of the β-subunits, and structural comparison reveals notable differences at the C termini, activity sites, and other regions. The disulfide comprising Cys156 to Cys162 stabilizes the C-terminal loop of the β-subunit and is crucial for oligomerization. Dynamic light scattering and ultracentrifugation measurements reveal multiple forms of APSR upon the addition of AMP, indicating that AMP binding dissociates the inactive hexamer into functional dimers, presumably by switching the C terminus of the β-subunit away from the active site. The crystal structure of APSR, together with its oligomerization properties, suggests that APSR from sulfate-reducing bacteria might self-regulate its activity through the C terminus of the β-subunit.
Penetration of the Blood-Brain Barrier by
Bacillus anthracis
Requires the pXO1-Encoded BslA Protein
Authors: Ebrahimi Celia M. , Kern Justin W. , Sheen Tamsin R. , Ebrahimi-Fardooee Mohammad A. , van Sorge Nina M. , Schneewind Olaf , Doran Kelly S.
Published: October 2009

Anthrax is a zoonotic disease caused by the gram-positive spore-forming bacterium
Bacillus anthracis
. Human infection occurs after the ingestion, inhalation, or cutaneous inoculation of
B. anthracis
spores. The subsequent progression of the disease is largely mediated by two native virulence plasmids, pXO1 and pXO2, and is characterized by septicemia, toxemia, and meningitis. In order to produce meningitis, blood-borne bacteria must interact with and breach the blood-brain barrier (BBB) that is composed of a specialized layer of brain microvascular endothelial cells (BMEC). We have recently shown that
B. anthracis
Sterne is capable of penetrating the BBB in vitro and in vivo, establishing the classic signs of meningitis; however, the molecular mechanisms underlying the central nervous system (CNS) tropism are not known. Here, we show that attachment to and invasion of human BMEC by
B. anthracis
Sterne is mediated by the pXO1 plasmid and an encoded envelope factor, BslA. The results of studies using complementation analysis, recombinant BslA protein, and heterologous expression demonstrate that BslA is both necessary and sufficient to promote adherence to brain endothelium. Furthermore, mice injected with the BslA-deficient strain exhibited a significant decrease in the frequency of brain infection compared to mice injected with the parental strain. In addition, BslA contributed to BBB breakdown by disrupting tight junction protein ZO-1. Our results identify the pXO1-encoded BslA adhesin as a critical mediator of CNS entry and offer new insights into the pathogenesis of anthrax meningitis.
Structure/Function Analysis of thePantoea stewartiiQuorum-Sensing Regulator EsaR as an Activator of Transcription
Authors: Schu Daniel J. , Carlier Aurelien L. , Jamison Katherine P. , von Bodman Susanne , Stevens Ann M.
Published: October 2009

InPantoea stewartiisubsp.stewartii, two regulatory proteins are key to the process of cell-cell communication known as quorum sensing: the LuxI and LuxR homologues EsaI and EsaR. Most LuxR homologues function as activators of transcription in the presence of their cognate acylated homoserine lactone (AHL) signal. However, EsaR was initially found to function as a repressor in the absence of AHL. Previous studies demonstrated that, in the absence of AHL, EsaR retains the ability to function as a weak activator of theluxoperon in recombinantEscherichia coli. Here it is shown that both the N-terminal and the C-terminal domains of EsaR are necessary for positive regulation. A site-directed mutagenesis study, guided by homology modeling to LuxR and TraR, has revealed three critical residues in EsaR that are involved in activation of RNA polymerase. In addition, a native EsaR-activated promoter has been identified, which controls expression of a putative regulatory sRNA inP. stewartii.
Cryo-Electron Tomography Elucidates the Molecular Architecture ofTreponema pallidum, the Syphilis Spirochete
Authors: Izard Jacques , Renken Christian , Hsieh Chyong-Ere , Desrosiers Daniel C. , Dunham-Ems Star , La Vake Carson , Gebhardt Linda L. , Limberger Ronald J. , Cox David L. , Marko Michael , Radolf Justin D.
Published: October 2009

Cryo-electron tomography (CET) was used to examine the native cellular organization ofTreponema pallidum, the syphilis spirochete.T. pallidumcells appeared to form flat waves, did not contain an outer coat and, except for bulges over the basal bodies and widening in the vicinity of flagellar filaments, displayed a uniform periplasmic space. Although the outer membrane (OM) generally was smooth in contour, OM extrusions and blebs frequently were observed, highlighting the structure's fluidity and lack of attachment to underlying periplasmic constituents. Cytoplasmic filaments converged from their attachment points opposite the basal bodies to form arrays that ran roughly parallel to the flagellar filaments along the inner surface of the cytoplasmic membrane (CM). Motile treponemes stably attached to rabbit epithelial cells predominantly via their tips. CET revealed thatT. pallidumcell ends have a complex morphology and assume at least four distinct morphotypes. Images of dividing treponemes and organisms shedding cell envelope-derived blebs provided evidence for the spirochete's complex membrane biology. In the regions without flagellar filaments, peptidoglycan (PG) was visualized as a thin layer that divided the periplasmic space into zones of higher and lower electron densities adjacent to the CM and OM, respectively. Flagellar filaments were observed overlying the PG layer, while image modeling placed the PG-basal body contact site in the vicinity of the stator-P-collar junction. Bioinformatics and homology modeling indicated that the MotB proteins ofT. pallidum,Treponema denticola, andBorrelia burgdorferihave membrane topologies and PG binding sites highly similar to those of their well-characterizedEscherichia coliandHelicobacter pyloriorthologs. Collectively, our results help to clarify fundamental differences in cell envelope ultrastructure between spirochetes and gram-negative bacteria. They also confirm that PG stabilizes the flagellar motor and enable us to propose that in most spirochetes motility results from rotation of the flagellar filaments against the PG.
Salmonella enterica
Serovar Typhimurium Can Detect Acyl Homoserine Lactone Production by
Yersinia enterocolitica
in Mice
Authors: Dyszel Jessica L. , Smith Jenee N. , Lucas Darren E. , Soares Jitesh A. , Swearingen Matthew C. , Vross Mathew A. , Young Glenn M. , Ahmer Brian M. M.
Published: October 2009

LuxR-type transcription factors detect acyl homoserine lactones (AHLs) and are typically used by bacteria to determine the population density of their own species.
Escherichia coli
and
Salmonella enterica
serovar Typhimurium cannot synthesize AHLs but can detect the AHLs produced by other bacterial species using the LuxR homolog, SdiA. Previously we determined that
S.
Typhimurium did not detect AHLs during transit through the gastrointestinal tract of a guinea pig, a rabbit, a cow, 5 mice, 6 pigs, or 12 chickens. However, SdiA was activated during transit through turtles colonized by
Aeromonas hydrophila
, leading to the hypothesis that SdiA is used for detecting the AHL production of other pathogens. In this report, we determined that SdiA is activated during the transit of
S.
Typhimurium through mice infected with the AHL-producing pathogen
Yersinia enterocolitica
. SdiA is not activated during transit through mice infected with a
yenI
mutant of
Y. enterocolitica
that cannot synthesize AHLs. However, activation of SdiA did not confer a fitness advantage in
Yersinia
-infected mice. We hypothesized that this is due to infrequent or short interactions between
S.
Typhimurium and
Y. enterocolitica
or that the SdiA regulon members do not function in mice. To test these hypotheses, we constructed an
S.
Typhimurium strain that synthesizes AHLs to mimic a constant interaction with
Y. enterocolitica
. In this background,
sdiA
+
S.
Typhimurium rapidly outcompetes the
sdiA
mutant in mice. All known members of the
sdiA
regulon are required for this phenotype. Thus, all members of the
sdiA
regulon are functional in mice.
Genome Sequence ofAggregatibacter actinomycetemcomitansSerotype c Strain D11S-1
Authors: Chen Casey , Kittichotirat Weerayuth , Si Yan , Bumgarner Roger
Published: October 2009

Aggregatibacter actinomycetemcomitansis a major etiological agent of periodontitis. Here we report the complete genome sequence of serotype c strain D11S-1, which was recovered from the subgingival plaque of a patient diagnosed with generalized aggressive periodontitis.