bluuebunny/crossref_metadata_2025 huggingface dataset:
Examining Congruence Between Partners' Perceived Infertility‐Related Stress and Its Relationship to Marital Adjustment and Depression in Infertile Couples
Authors: Peterson Brennan D. , Newton Christopher R. , Rosen Karen H.
Published: August 2004

Because studies examining the emotional impact of infertility‐related stress generally focus on individuals, there has been little research examining how relationship and individual Variables are linked. The purpose of this study was to explore the impact of congruence (e.g., agreement) between partner's perceived infertility‐related stress and its effects on depression and marital adjustment in infertile men and women. Couples referred for infertility treatments at a University‐affiliated teaching hospital completed the Fertility Problem Inventory (FPI), the Beck Depression Inventory (BDI), and the Dyadic Adjustment Scale (DAS) 3 months prior to their first treatment cycle. Study findings show that men and women in couples who perceived equal levels of social infertility stress reported higher levels of marital adjustment when compared to men and women in couples who perceived the stress differently. In addition, women in couples who felt a similar need for parenthood reported significantly higher levels of marital satisfaction when compared to women in couples where the males reported a greater need for parenthood. While couple incongruence was unrelated to depression in males, incongruence over relationship concerns and the need for parenthood was related to female depression. These findings provide initial support for the theory that high levels of agreement between partners related to the stresses they experience help them successfully manage the impact of these stressful life events. Possibilities for future research examining the construct of couple congruence are discussed.
Burden in Schizophrenia Caregivers: Impact of Family Psychoeducation and Awareness of Patient Suicidality
Authors: McDonell Michael G. , Short Robert A. , Berry Christopher M. , Dyck Dennis G.
Published: August 2004

Family caregivers of persons with schizophrenia and other psychotic disorders experience high levels of burden. Although a number of patient and caregiver predictors of burden have been identified, little research has investigated the contributions of patient depression, suicidal ideation, and substance abuse. In addition, family psychoeducation interventions have reduced patient symptoms, as well as inpatient treatment utilization; however, it is not known whether or not these interventions reduce family burden. This study‐ investigated predictors of family burden and tested to what degree multiple family group treatment (MFGT), relative to a standard‐care condition, was associated with reduced family burden. Participants were 90 outpatients with a diagnosis of schizophrenia or other psychotic disorders, and their caregivers who were enrolled in a 2 year psychoeducation intervention. The best set of predictors of burden, identified by stepwise linear regression, was young patient age, awareness of patient's suicidal ideation, and family resources. These variables accounted for 32% of the total variance in burden. Findings suggest that caregiver's awareness of patient's suicidal ideation; not patient's report of suicidal ideation; and that patient age not duration of the illness, were significant, independent predictors of burden. When compared to a standard‐care condition over 2 years, MFGT did not reduce family caregiver burden. Discussions focus on the relationship between burden and its predictors, and possible reasons why MFGT did not decrease burden. Modifications are proposed that may increase the impact of MFGT.
Parental Values and Ethnic Identity in Indigenous Sami Families: A Qualitative Study
Authors: Javo Cecilie , Alapack Richard , Heyerdahl Sonja , Røsnning John A.
Published: August 2004

The qualitative study reported in this article is part of a larger multimethod investigation of child‐rearing practices and child‐behavior problems in indigenous Sami and majority Norwegian populations in the Sami core area in Northern Norway. In the primary quantitative study we found significant ethnic differences between Sami and Norwegian parents in various areas of child rearing and family structure. Seeking the deeper cultural meaning underlying the parental practices and attitudes that had emerged in the indigenous Sami group, we performed additional in depth interviews. Four parents, selected from the sample of 134 Sami parents, served as subjects. Giorgi's descriptive phenomenological method was used. Data analysis of the interviews identified seven key constituents of Sami child rearing, which in their interrelationships formed a common structure that constitutes the results of this study. These constituents were: (1) Independence, (2) Hardiness, (3) Autonomy, (4) Closeness/Love, (5) Sami Language, (6) Sami Traditions, and (7) Extended Family. The first four constituents are constituents pertaining to child‐rearing values, while the latter three are contextual constituents, related to the promotion of ethnic identity. The study discusses the contemporary dilemmas and challenges that face Sami families in raising their children. It highlights the phenomenon of cultural transition in minority families as an important topic in family research.
Solution‐Focused Family Therapy With Three Aggressive and Oppositional‐Acting Children: An N = 1 Empirical Study
Authors: CONOLEY COLLIE. W. , GRAHAM JAMES M. , NEU TODD , CRAIG MARLA C. , O'PRY AMY , CARDIN SCOTT A. , BROSSART DANIEL F. , PARKER RICHARD I.
Published: August 2004

The efficacy of Solution‐Focused Family Therapy (SFFT)for helping three families with aggressive and oppositional‐acting children (aged 8–9). was examined. The N = 1 multiple‐baseline design with three replications used validated measures, a treatment integrity measure. The interventions lasted from four to five sessions. SFFT appeared to be effective with the families at post‐treatment and 3‐month follow up.
Family Predictors of Disease Management Over One year in Latino and European American Patients with Type 2 Diabetes*
Authors: CHESLA CATHERINE A. , FISHER LAWRENCE , SKAFF MARILYN M. , MULLAN JOSEPH T. , GILLISS CATHERINE L. , KANTER RICHARD
Published: August 2004

Family context is thought to influence chronic disease management but few studies have longitudinally examined these relationships. Research on families and chronic illness has focused almost exclusively on European American families. In this prospective study we tested a multidimensional model of family influence on disease management in type 2 diabetes in a bi‐ethnic sample of European Americans and Latinos. Specifically, we tested how baseline family characteristics (structure, world view, and emotion management) predicted change in disease management over one year in 104 European American and 57 Latino patients with type 2 diabetes. We found that emotion management predicted change in disease management in both groups of patients as hypothesized while family world view predicted change in both ethnic groups but in the predicted direction only for European Americans Examining family context within ethnic groups is required to elucidate unique cultural patterns. Attending to culturally unique interpretations of constructs and measures is warranted. The import of family emotion management specifically conflict resolution in disease management deserves further study to support clinical intervention development. Examining multiple domains of family life and multidimensional health outcomes strengthens out capacity to develop theory about family contexts and individual health.
Relationships Between Adult Attachment Representations and Family Ritual Quality: A Prospective, Longitudinal Study
Authors: LEON KIM , JACOBVITZ DEBORAH B.
Published: August 2004

Meaningful family rituals have been associated with positive outcomes for families and children. No studies, however, have investigated predictors of family ritual quality, the identification of which would be important for understanding why some families create and enact meaningful family rituals while others lack rituals or have problematic rituals. We propose that adult attachment security may be an important predictor of family ritual quality because family rituals may provide a sense of stability and cohesiveness for the family. The purpose of this study was to examine relationships between adult attachment representations and the quality of family rituals, using a prospective, longitudinal design. Prior to the birth of their first child, 125 couples completed the Adult Attachment Interview, and a subsample of 70 mothers and 62 fathers completed the Family Rituals Questionnaire when their first child was 7 years old. Different patterns of relationships between attachment representations and family rituals were found for mothers and fathers. Maternal Insecure Attachment was associated with higher routinization of family rituals. Being in a couple with mixed attachment classifications (e.g., one Secure partner and one Insecure partner) was related to a pattern of low routinization and low meaning for family rituals. The results of this study are interpreted in terms of two patterns of rituals that have been described by clinicians‐rigid ritualization and underritualization, and suggestions for working with these ritual patterns in families with Insecure attachment are provided.
Family Members' Knowledge about Borderline Personality Disorder: Correspondence with their Levels of Depression, Burden, Distress, and Expressed Emotion
Authors: HOFFMAN PERRY D. , BUTEAU ELLIE , HOOLEY JILL M. , FRUZZETO ALAN E. , BRUCE MARTHA L.
Published: August 2004

Borderline personality disorder (BPD) is a severe and generally chronic disorder that presents patients and their family members with multiple challenges. Little is currently known about how much family members of patients with BPD know about this disorder. Thirty‐two family members of BPD patients were assessed for their level of knowledge about BPD. Knowledge level was then correlated with family members' burden, depression, distress, and expressed emotion. Contrary to expectation, greater knowledge about BPD was associated with higher levels of family members' burden, distress, depression, and greater hostility toward patients. These findings raise concerns about (a) the value of information family members receive about BPD and (b) the importance of the source and accuracy of the information they receive. Further research is warranted and may provide additional information to this understudied area.
The Psychological Effects of Parental Mental Health on Children Experiencing Disaster: The Experience of Bolu Earthquake in Turkey
Authors: KILIÇ EMINE ZINNUR , ÖZGÜVEN HALISE DEVRIMCI , SAYIL IAIK
Published: August 2004

Disasters affect families as a whole, and symptoms displayed by a family member may lead to secondary traumatizations for other members of the family, especially the children. This study examines the effects of parental psychopathology and family functioning on children's psychological problems six months after the earthquake in Bolu, Turkey. Forty‐nine children aged between 7 and 14 and their parents were randomly chosen from among 800 families living in a survivor camp in Bolu. Both the children and parents were assessed by trained psychiatrists and psychologists using self‐report measures for posttraumatic stress disorder (PTSD), depression, and anxiety symptoms six months after the earthquake. Family functioning in survivor families was also assessed using the Family Assessment Device (FAD). The results showed that the severity of PTSD in children was mainly affected by the presence of PTSD and the severity of depression in the father. State and. trait anxiety scores of children were related to general family functioning. The constellation of PTSD symptomatology was different in fathers than in mothers: the most common type of symptoms was “externalizing” in fathers with PTSD. This study supports the notion that the mere presence of PTSD in parents may not be enough to explain the relational process in families experiencing trauma. Our findings with earthquake survivors suggest that when fathers become more irritable and detached because of PTSD symptoms, their symptoms may affect children more significantly.
On Relevant Ramberg-Osgood Fit to Engineering Nonlinear Fracture Mechanics Analysis
Authors: Kim Yun-Jae , Huh Nam-Su , Kim Young-Jin , Choi Young-Hwan , Yang Jun-Seok
Published: August 2004

The present paper proposes a robust method for the Ramberg-Osgood (R-O) fit to accurately estimate elastic-plastic J from the engineering fracture mechanics analysis based on deformation plasticity. The proposal is based on engineering stress-strain data to determine the R-O parameters, instead of true stress-strain data. Moreover, for practical applications, the method is given not only for the case when full stress-strain data are available but also for the case when only yield and tensile strengths are available. The reliability of the proposed method for the R-O fit is validated against detailed three-dimensional FE analyses for through-wall cracked pipes under global bending using five different materials, three stainless steels and two ferritic steels. Taking the FE J results based on incremental plasticity using actual stress-strain data as the reference, the FE J results based on deformation plasticity using various R-O fits are compared with reference J values. Comparisons show that the proposed R-O fit provides more accurate J values for all cases, compared to existing methods for the R-O fit. Advantages of the proposed R-O fit in practical applications are discussed, together with its accuracy.
C-Specimen Fracture Toughness Testing: Effect of Side Grooves and η Factor
Authors: Kim Y. , Chao Y. J. , Pechersky M. J. , Morgan M. J.
Published: August 2004

Elastic-plastic crack front fields in arc-shaped tension specimens (C-specimens) were analyzed by a three-dimensional finite element method. The effect of side grooves on the ductile fracture behavior was investigated by studying the J-integral distribution, plane-strain constraint parameter, and development of plastic zones and comparing to experimental data. The applicability of the η factor (derived for use with compact tension specimens) for the calculation of J-integral values for the C-specimen was also investigated. The results show that side grooves promote and establish near plane strain conditions at the crack front in sub-size specimens. It was also found that a two-dimensional plane-strain analysis in conjunction with the standard American Society for Testing and Materials (ASTM) tests was sufficient to determine the fracture toughness values from side-grooved C-specimen. The results indicate the η factor for compact tension specimen as specified in the ASTM standards appears to produce reliable results for the calculation of J of C-specimens.
Determination of Discharge Coefficients for Hydraulic Sparger Design
Authors: Gregg Walter Boyd , Werth David E. , Frizzell Carl
Published: August 2004

This paper provides design examples and summarizes a study on the determination of multiple free discharge orifice coefficients in a circular walled manifold for a variety of shapes and area projections. A simplified design procedure is presented which allows engineers to accurately maintain a given pressure and flow at the entrance to the sparger. The design provides for uniform flow across the cooling tower basin, and prevents an increase in back pressure or open channel flow within the sparger, minimizing the effect of surging or pressure fluctuations on upstream performance.
Comments on Design Methods of Penstocks
Authors: Jian-Guo Hou , Xu-Wen An , Ying-Min He
Published: August 2004

This paper selects several representative penstocks codes of hydropower stations in China and foreign countries including USBR Standards (1970), ASCE Steel Penstocks (1993), Japanese Technical Standards for Gates and Penstocks (1993), the former USSR’s code My 34 747-76 and Π 780-83, and Chinese code DL/T 5141-2001; analyzes and compares their different design methods and corresponding safety levels. In addition, the probabilistic limit state design method adopted in DL/T 5141-2001 is described emphatically. What are described can be taken as reference by the engineering technicians who are engaged in the research, design and construction of steel penstocks for hydropower stations at home and abroad.
A Modified Power Law for Creep Analysis
Authors: Katcher Michael
Published: August 2004

The creep strengths for an annealed Ni-33Fe-25Cr alloy, UNS N08120 (HAYNES® HR-120® alloy) are presented from 593°C to 1204°C at every 56°C for lives up to 30,000 hours. The creep data are used as a basis for converting the power law method (log stress versus log time at a defined temperature) to the usefulness of the Larson-Miller method for design creep analysis. A new empirical relationship was developed between stress, temperature and creep rupture life. Power Law equations were generated at each temperature using linear regression of the transformed data to obtain the best-fit constants. The constants were then plotted and a best-fit polynomial of the constants as a function of temperature was determined. The polynomial then replaced the constants in the original power law equation to obtain a single expression of stress as a function of time and temperature. Using this new Modified Power Law (MPL) equation, interpolation or extrapolation to obtain stress becomes possible for any temperature and time.
Surface and Bulk Residual Stress in Ti6Al4V Welded Aerospace Tanks
Authors: Bruno G. , Dunn B. D.
Published: August 2004

The residual stress (RS) in two curved plates cut from a large welded propellant tank for spacecrafts was investigated nondestructively by neutron and laboratory x-ray diffraction. Each plate had two weld beads symmetric to a central monoblock reinforcement. One plate had received a post-weld heat-treatment. The two nondestructive test techniques successfully determined both the bulk (thickness averaged) and the surface stress state, due to the highly different penetration of these radiations in metals. In the as-welded tank, both neutrons and x-rays show a stress level (both in the axial and hoop directions) higher in the heat affected zone (HAZ) than in the weld pool (300 against 160 MPa). A considerable degree of relaxation annealing was observed by neutron diffraction after the application of the heat treatment. In this case, the hoop stress in the HAZ relaxes from about 300 to about 100 MPa. X-rays also permitted the separate determination of the α and β-phase stresses and the calculation of the macro-RS. The latter showed the bending deformation resulting from the cut of the plates from the original tank. The average stress measured by x-rays was found to be very similar to the RS obtained by neutron diffraction technique.
Validation of the Isis-3D Computer Code for Simulating Large Pool Fires Under a Variety of Wind Conditions
Authors: Greiner Miles , Suo-Anttila Ahti
Published: August 2004

The Isis-3D computational fluid dynamics/radiation heat transfer computer code was developed to simulate heat transfer from large fires to engulfed packages for transportation risk studies. These studies require accurate estimates of the total heat transfer to an object and the general characteristics of the object temperature distribution for a variety of fire environments. Since risk studies require multiple simulations, analysis tools must be rapid as well as accurate. In order to meet these needs Isis-3D employs fuel evaporation reaction rate and radiation heat transfer models that allow it to accurately model large-fire heat transfer even when relatively coarse computational grids are employed. Reaction rate and soot radiation model parameters in Isis-3D have been selected based on experimental data. In this work, Isis-3D calculations were performed to simulate the conditions of three experiments that measured the temperature response of a 4.66 m diameter culvert pipe located at the leeward edge of 18.9 m and 9.45 m diameter pool fires in crosswinds with average speeds of 2.0, 4.6, and 9.5 m/s. Isis-3D accurately calculated the time-dependent temperatures in all three experiments. Accelerated simulations were performed in which the pipe specific heat was reduced compared to the measured value by a factor of four. This artificially increased the speed at which the pipe temperature rose and allowed the simulated fire duration to be reduced by a factor of four. A 700 sec fire with moderately unsteady wind conditions was accurately simulated in 10 hours on a standard workstation.
Two-Dimensional Finite Element Analysis for Large Diameter Steel Flanges
Authors: Alghamdi Abdulmalik A. , Al-Sannaa Muhsen S.
Published: August 2004

This paper presents numerical results obtained using Finite Element Analysis (FEA) in studying large diameter welded neck steel flanges under different loading conditions. Obtained FEA results show the effect of the clamping pressure, internal pressure, axial end load, temperature effect, gasket elasticity modulus on the contact pressure between the gasket and the steel flange. As expected clamping pressure is a determinate factor for the sealing condition. Gasket material is another primary factor in designing flanged joints.
Residual Stress Induced by Waterjet Peening: A Finite Element Analysis
Authors: Kunaporn S. , Ramulu M. , Jenkins M. G. , Hashish M.
Published: August 2004

The concept of multiple droplet impacts resulting from ultra high-pressure waterjet (UHPWJ) was used to develop a mathematical model to describe the effect of interfacial pressure on the underlying workpiece material. A non-linear elastic-plastic finite element analysis (FEA) was carried out in this study using the interfacial pressure model to predict residual compressive stresses. This three-dimensional FEA model was based on quasi-static considerations to provide prediction of both magnitude and depth of residual stress fields in a 7075-T6 aluminum alloy (A17075-T6). Results of the FEA modeling were in good agreement with experimental measurements. Effects of applied pressures on the residual stress fields are also presented and discussed as a method of estimating high-pressure waterjet induced compressive stresses under varying process conditions for peening.
Appropriate Correlations for Assessing Expanded Tube-to-Tubesheet Joint Strength
Authors: Yokell Stanley
Published: August 2004

This paper advocates correlating rolling torque or hydraulic expanding pressure with shear load strength instead of percent wall reduction as the criterion of expanding adequacy for thin-walled tubes. It compares magnitudes of measurements required to estimate wall reduction with cumulative hole-drilling and tube-manufacturing tolerances and graphically illustrates data scatter increase with ratio of tube diameter to wall thickness. As background it discusses expanding theory. It covers hydraulic, roller and hybrid expanding. It describes appropriate annular groove widths for hydraulic and hybrid expanding and concludes with comments on tube rolling procedure specifications and recommendations for two-stage and hybrid expanding.
Closed-Form Collapse Moment Equations of Throughwall Circumferentially Cracked Elbows Subjected to In-Plane Bending Moment
Authors: Chattopadhyay J. , Tomar A. K. S. , Dutta B. K. , Kushwaha H. S.
Published: August 2004

A large throughwall circumferential crack in an elbow subjected to in-plane bending moment can significantly reduce its collapse load. Therefore, it is very important to know the collapse moment of an elbow in the presence of a throughwall circumferential crack. The existing closed-form collapse moment equations of throughwall circumferentially cracked elbows are either too conservative or inadequate to correctly quantify the weakening effect due to the presence of the crack, especially for opening mode of bending moment. Therefore, the present study has been carried out to investigate through elastic-plastic finite element analysis the effect of a throughwall circumferential crack on the collapse moment of an elbow under in-plane bending moment. A total of 72 cases of elbows with various sizes of circumferential cracks (2θ=0–150 deg), different wall thickness (R/t=5–20), different elbow bend radii Rb/R=2,3 and two different bending modes, namely closing and opening have been considered in the analysis. Elastic-perfectly plastic stress-strain response of material has been assumed. Collapse moments have been evaluated from moment-end rotation curves by twice-elastic slope method. From these results, closed-form expressions have been proposed to evaluate collapse moments of elbows under closing and opening mode of bending moment. The predictions of these proposed equations have been compared with 8 published elbow test data and are found to be within ±11% variation except for one case.
The Application of Physically Based CDM Modeling in Prediction of Materials Properties and Component Lifetime
Authors: Yang J. , Hsiao J. S. , Fong M. , Gibbons T. B.
Published: August 2004

Since the early empirically based work of Kachanov and Robotnov substantial progress has been made in developing the concept of Continuum Damage Mechanics (CDM) as a tool for predicting material and component behavior in the creep regime. The key element in this process has been the progress that has been made in understanding and quantifying the physics of deformation and fracture in engineering alloys for high temperature service. In this paper, the application of the CDM methodology has been demonstrated in the prediction of the creep behavior of alloy steels for boiler pressure parts and for predicting the life to failure of model components and tubular testpieces operating in creep conditions. A model incorporating two damage state variables formed the basis of the methodology for creep behavior and a multi-axial variant of the model was used for the component life prediction. The important development described in this work has been the use of a simplifying procedure in dealing with damaged elements in the finite-element model, so that the analysis for component life prediction can be carried out on a personal computer rather than the large mainframe computers used previously. This greatly increases the usefulness of the procedure for practical design applications. The results show that the CDM methodology can be applied successfully in these important applications and will give much more satisfactory agreement with experiment than existing less robust methods. In addition the failure profile of the tubular testpieces can be accurately represented and this is a feature unique to the CDM approach.
Stability of Vertically Bent Pipelines Buried in Sand
Authors: Abduljauwad Sahel N. , Al-Ghamedy Hamdan N. , Siddiqui Junaid A. , Asi Ibrahim M. , Al-Shayea Naser A.
Published: August 2004

This paper discusses the stability of underground pipelines with preformed vertical bends buried in sandy soil. More specifically, the minimum cover height required to prevent the pipe from bowing under the action of forces due to temperature change and internal pressure is estimated. The variables considered include the pipe and soil materials, diameter, thickness, overburden height, bend radius, bend angle, internal pressure, fluid specific weight, and temperature variation. A comprehensive three-dimensional finite element analysis is carried out. The results are extracted from the output obtained. These results are put in a database which is used to develop general regression models to determine the relationships among the different variables. Different buckling modes are also considered. All of these results and models are entered into a computer software program for ready access.
Genetic Recombination inBacillus subtilis168: Contribution of Holliday Junction Processing Functions in Chromosome Segregation
Authors: Carrasco Begoña , Cozar M. Castillo , Lurz Rudi , Alonso Juan C. , Ayora Silvia
Published: August 2004

Bacillus subtilismutants classified within the ε (ruvA, ΔruvB, ΔrecU, andrecD) and η (ΔrecG) epistatic groups, in an otherwiserec+background, render cells impaired in chromosomal segregation. A less-pronounced segregation defect in ΔrecAand Δsms(ΔradA) cells was observed. The repair deficiency ofaddAB, ΔrecO, ΔrecR,recH, ΔrecS, and ΔsubAcells did not correlate with a chromosomal segregation defect. The sensitivity of ε epistatic group mutants to DNA-damaging agents correlates with ongoing DNA replication at the time of exposure to the agents. The Δsms(ΔradA) and ΔsubAmutations partially suppress the DNA repair defect inruvAandrecDcells and the segregation defect inruvAand ΔrecGcells. The Δsms(ΔradA) and ΔsubAmutations partially suppress the DNA repair defect of ΔrecUcells but do not suppress the segregation defect in these cells. The ΔrecAmutation suppresses the segregation defect but does not suppress the DNA repair defect in ΔrecUcells. These results result suggest that (i) the RuvAB and RecG branch migrating DNA helicases, the RecU Holliday junction (HJ) resolvase, and RecD bias HJ resolution towards noncrossovers and that (ii) Sms (RadA) and SubA proteins might play a role in the stabilization and or processing of HJ intermediates.
Transglutaminase-Mediated Cross-Linking of GerQ in the Coats of
Bacillus subtilis
Spores
Authors: Ragkousi Katerina , Setlow Peter
Published: August 2004

The spores of
Bacillus subtilis
show remarkable resistance to many environmental stresses, due in part to the presence of an outer proteinaceous structure known as the spore coat. GerQ is a spore coat protein essential for the presence of CwlJ, an enzyme involved in the hydrolysis of the cortex during spore germination, in the spore coat. Here we show that GerQ is cross-linked into higher-molecular-mass forms due in large part to a transglutaminase. GerQ is the only substrate for this transglutaminase identified to date. In addition, we show that cross-linking of GerQ into high-molecular-mass forms occurs only very late in sporulation, after mother cell lysis. These findings, as well as studies of GerQ cross-linking in mutant strains where spore coat assembly is perturbed, lead us to suggest that coat proteins must assemble first and that their cross-linking follows as a final step in the spore coat formation pathway.
The LysR-Type Transcriptional Regulator VirR Is Required for Expression of the Virulence GenevapAofRhodococcus equiATCC 33701
Authors: Russell Dean A. , Byrne Gavin A. , O'Connell Enda P. , Boland Clara A. , Meijer Wim G.
Published: August 2004

The virulence of the intracellular pathogenRhodococcus equiin foals is dependent on the presence of an 81-kb virulence plasmid encoding the virulence protein VapA. Expression of this protein is induced by exposure to oxidative stress, high temperatures, and low pHs, which reflect the conditions encountered byR. equiwhen it enters the host environment. The aim of this study was to determine whether the LysR-type transcriptional regulator VirR, which is encoded by the virulence plasmid, is required for the expression ofvapA. It was shown that thevirRgene is cotranscribed with four downstream genes, one of which encodes a two-component response regulator. The expression of VapA, as monitored by Western blotting, was completely dependent on the presence ofvirR. Maximal expression was observed whenvapAwas present together with the completevirRoperon, suggesting that at least one of the virR operon genes, in addition tovirR, is required for the expression ofvapAto wild-type levels. The transcriptional start site ofvapAwas determined to be a cytidine located 226 bp upstream from thevapAinitiation codon. His-tagged VirR protein was expressed inEscherichia coliand purified by nickel affinity chromatography. DNA binding studies showed that purified VirR binds to a DNA fragment containing thevapApromoter. We therefore conclude that VirR is required for the activation ofvapAtranscription.
Identification and Transcriptional Control of
Caulobacter crescentus
Genes Encoding Proteins Containing a Cold Shock Domain
Authors: Lang Elza A. S. , Marques Marilis V.
Published: August 2004

The cold shock proteins are small peptides that share a conserved domain, called the cold shock domain (CSD), that is important for nucleic acid binding. The
Caulobacter crescentus
genome has four
csp
genes that encode proteins containing CSDs. Three of these (
cspA
,
cspB
, and
cspC
) encode peptides of about 7 kDa and are very similar to the cold shock proteins of other bacteria. Analysis by reverse transcription-PCR of the fourth gene (
cspD
), which was previously annotated as encoding a 7-kDa protein, revealed that the mRNA is larger and probably encodes a putative 21-kDa protein, containing two CSDs. A search in protein sequences databases revealed that this new domain arrangement has thus far only been found among deduced peptides of α-proteobacteria. Expression of each
Caulobacter csp
gene was studied both in response to cold shock and to growth phase, and we have found that only
cspA
and
cspB
are induced by cold shock, whereas
cspC
and
cspD
are induced at stationary phase, with different induction rates. The transcription start sites were determined for each gene, and a deletion mapping of the
cspD
promoter region defined a sequence required for maximal levels of expression, indicating that regulation of this gene occurs at the transcriptional level. Deletion of
cspA
, but not
cspD
, caused a reduction in viability when cells were incubated at 10°C for prolonged times, suggesting that
cspA
is important for adaptation to a low temperature.
A Regulatory Trade-Off as a Source of Strain Variation in the Species
Escherichia coli
Authors: King Thea , Ishihama Akira , Kori Ayako , Ferenci Thomas
Published: August 2004

There are few existing indications that strain variation in prokaryotic gene regulation is common or has evolutionary advantage. In this study, we report on isolates of
Escherichia coli
with distinct ratios of sigma factors (RpoD, σ
D
, or σ
70
and RpoS or σ
S
) that affect transcription initiated by RNA polymerase. Both laboratory
E. coli
K-12 lineages and nondomesticated isolates exhibit strain-specific endogenous levels of RpoS protein. We demonstrate that variation in genome usage underpins intraspecific variability in transcription patterns, resistance to external stresses, and the choice of beneficial mutations under nutrient limitation. Most unexpectedly, RpoS also controlled strain variation with respect to the metabolic capability of bacteria with more than a dozen carbon sources. Strains with higher σ
S
levels were more resistant to external stress but metabolized fewer substrates and poorly competed for low concentrations of nutrients. On the other hand, strains with lower σ
S
levels had broader nutritional capabilities and better competitive ability with low nutrient concentrations but low resistance to external stress. In other words, RpoS influenced both
r
and
K
strategist functions of bacteria simultaneously. The evolutionary principle driving strain variation is proposed to be a conceptually novel trade-off that we term SPANC (for “self-preservation and nutritional competence”). The availability of multiple SPANC settings potentially broadens the niche occupied by a species consisting of individuals with narrow specialization and reveals an evolutionary advantage offered by polymorphic regulation. Regulatory diversity is likely to be a significant contributor to complexity in a bacterial world in which multiple sigma factors are a universal feature.
Slr1293 in
Synechocystis
sp. Strain PCC 6803 Is the C-3′,4′ Desaturase (CrtD) Involved in Myxoxanthophyll Biosynthesis
Authors: Mohamed Hatem E. , Vermaas Wim
Published: August 2004

When grown at high light intensity, more than a quarter of the total carotenoids in the unicellular cyanobacterium
Synechocystis
consists of myxoxanthophyll, a polar carotenoid glycoside. The biosynthetic pathway of myxoxanthophyll is unknown but is presumed to involve a number of enzymes, including a C-3′,4′ desaturase required to add one double bond to generate 11 conjugated double bonds in the monocyclic myxoxanthophyll. A candidate for this desaturase is Slr1293, which was identified by genome similarity searching. To determine whether Slr1293 is a desaturase recognizing neurosporene and lycopene,
slr1293
was expressed in
Escherichia coli
strains accumulating neurosporene or lycopene. Confirming such a desaturase function for Slr1293, these
E. coli
strains accumulated 3′,4′-didehydroneurosporene and 3′,4′-didehydrolycopene, respectively. Indeed, deletion of
slr1293
in
Synechocystis
provides further evidence that Slr1293 is a desaturase recognizing neurosporene: In the
slr1293
deletion mutant, neurosporene was found to accumulate and was further processed to produce neurosporene glycoside. Neurosporene hereby becomes a primary candidate to be the branch point molecule between carotene and myxoxanthophyll biosynthesis in this cyanobacterium. The
slr1293
gene was concluded to encode a C-3′,4′ desaturase that is essential for myxoxanthophyll biosynthesis, and thus it was designated as
crtD
. Furthermore, as Slr1293 appears to recognize neurosporene and to catalyze the first committed step on the myxoxanthophyll biosynthesis pathway, Slr1293 plays a pivotal role in directing a portion of the precursor pool for carotenoid biosynthesis toward myxoxanthophyll biosynthesis in
Synechocystis
sp. strain PCC 6803.
Bacillus subtilisLmrA Is a Repressor of thelmrABandyxaGHOperons: Identification of Its Binding Site and Functional Analysis oflmrBandyxaGH
Authors: Yoshida Ken-ichi , Ohki Yo-hei , Murata Makiko , Kinehara Masaki , Matsuoka Hiroshi , Satomura Takenori , Ohki Reiko , Kumano Miyuki , Yamane Kunio , Fujita Yasutaro
Published: August 2004

TheBacillus subtilis lmrABoperon is involved in multidrug resistance. LmrA is a repressor of its own operon, while LmrB acts as a multidrug efflux transporter. LmrA was produced inEscherichia colicells and was shown to bind to thelmrpromoter region, in which an LmrA-binding site was identified. Genome-wide screening involving DNA microarray analysis allowed us to conclude that LmrA also repressedyxaGH, which was not likely to contribute to the multidrug resistance. LmrA bound to a putativeyxaGHpromoter region, in which two tandem LmrA-binding sites were identified. The LmrA regulon was thus determined to compriselmrABandyxaGH. All three LmrA-binding sites contained an 18-bp consensus sequence, TAGACCRKTCWMTATAWT, which could play an important role in LmrA binding.
Acid-Inducible Transcription of the Operon Encoding the Citrate Lyase Complex of
Lactococcus lactis
Biovar diacetylactis CRL264
Authors: Martín Mauricio G. , Sender Pablo D. , Peirú Salvador , de Mendoza Diego , Magni Christian
Published: August 2004

Although
Lactococcus
is one of the most extensively studied lactic acid bacteria and is the paradigm for biochemical studies of citrate metabolism, little information is available on the regulation of the citrate lyase complex. In order to fill this gap, we characterized the genes encoding the subunits of the citrate lyase of
Lactococcus lactis
CRL264, which are located on an 11.4-kb chromosomal DNA region. Nucleotide sequence analysis revealed a cluster of eight genes in a new type of genetic organization. The
citM-citCDEFXG
operon (
cit
operon) is transcribed as a single polycistronic mRNA of 8.6 kb. This operon carries a gene encoding a malic enzyme (CitM, a putative oxaloacetate decarboxylase), the structural genes coding for the citrate lyase subunits (
citD
,
citE
, and
citF
), and the accessory genes required for the synthesis of an active citrate lyase complex (
citC
,
citX
, and
citG
). We have found that the
cit
operon is induced by natural acidification of the medium during cell growth or by a shift to media buffered at acidic pHs. Between the
citM
and
citC
genes is a divergent open reading frame whose expression was also increased at acidic pH, which was designated
citI
. This inducible response to acid stress takes place at the transcriptional level and correlates with increased activity of citrate lyase. It is suggested that coordinated induction of the citrate transporter, CitP, and citrate lyase by acid stress provides a mechanism to make the cells (more) resistant to the inhibitory effects of the fermentation product (lactate) that accumulates under these conditions.
Cloning and Expression of
afpA
, a Gene Encoding an Antifreeze Protein from the Arctic Plant Growth-Promoting Rhizobacterium
Pseudomonas putida
GR12-2
Authors: Muryoi Naomi , Sato Mika , Kaneko Shoji , Kawahara Hidehisa , Obata Hitoshi , Yaish Mahmoud W. F. , Griffith Marilyn , Glick Bernard R.
Published: August 2004

The Arctic plant growth-promoting rhizobacterium
Pseudomonas putida
GR12-2 secretes an antifreeze protein (AFP) that promotes survival at subzero temperatures. The AFP is unusual in that it also exhibits a low level of ice nucleation activity. A DNA fragment with an open reading frame encoding 473 amino acids was cloned by PCR and inverse PCR using primers designed from partial amino acid sequences of the isolated AFP. The predicted gene product, AfpA, had a molecular mass of 47.3 kDa, a pI of 3.51, and no previously known function. Although AfpA is a secreted protein, it lacked an N-terminal signal peptide and was shown by sequence analysis to have two possible secretion systems: a hemolysin-like, calcium-binding secretion domain and a type V autotransporter domain found in gram-negative bacteria. Expression of
afpA
in
Escherichia coli
yielded an intracellular 72-kDa protein modified with both sugars and lipids that exhibited lower levels of antifreeze and ice nucleation activities than the native protein. The 164-kDa AFP previously purified from
P. putida
GR12-2 was a lipoglycoprotein, and the carbohydrate was required for ice nucleation activity. Therefore, the recombinant protein may not have been properly posttranslationally modified. The AfpA sequence was most similar to cell wall-associated proteins and less similar to ice nucleation proteins (INPs). Hydropathy plots revealed that the amino acid sequence of AfpA was more hydrophobic than those of the INPs in the domain that forms the ice template, thus suggesting that AFPs and INPs interact differently with ice. To our knowledge, this is the first gene encoding a protein with both antifreeze and ice nucleation activities to be isolated and characterized.
Identification of AlgR-Regulated Genes in
Pseudomonas aeruginosa
by Use of Microarray Analysis
Authors: Lizewski Stephen E. , Schurr Jill R. , Jackson Debra W. , Frisk Anders , Carterson Alexander J. , Schurr Michael J.
Published: August 2004

The
Pseudomonas aeruginosa
transcriptional regulator AlgR controls a variety of different processes, including alginate production, type IV pilus function, and virulence, indicating that AlgR plays a pivotal role in the regulation of gene expression. In order to characterize the AlgR regulon,
Pseudomonas
Affymetrix GeneChips were used to generate the transcriptional profiles of (i)
P. aeruginosa
PAO1 versus its
algR
mutant in mid-logarithmic phase, (ii)
P. aeruginosa
PAO1 versus its
algR
mutant in stationary growth phase, and (iii) PAO1 versus PAO1 harboring an
algR
overexpression plasmid. Expression analysis revealed that, during mid-logarithmic growth, AlgR activated the expression of 58 genes while it repressed the expression of 37 others, while during stationary phase, it activated expression of 45 genes and repression of 14 genes. Confirmatory experiments were performed on two genes found to be AlgR repressed (
hcnA
and
PA1557
) and one AlgR-activated operon (
fimU
-
pilVWXY1Y2
). An S1 nuclease protection assay demonstrated that AlgR repressed both known
hcnA
promoters in PAO1. Additionally, direct measurement of hydrogen cyanide (HCN) production showed that
P. aeruginosa
PAO1 produced threefold-less HCN than did its
algR
deletion strain. AlgR also repressed transcription of two promoters of the uncharacterized open reading frame
PA1557
. Further, the twitching motility defect of an
algR
mutant was complemented by the
fimTU-pilVWXY1Y2E
operon, thus identifying the AlgR-controlled genes responsible for this defect in an
algR
mutant. This study identified four new roles for AlgR: (i) AlgR can repress gene transcription, (ii) AlgR activates the
fimTU-pilVWXY1Y2E
operon, (iii) AlgR regulates HCN production, and (iv) AlgR controls transcription of the putative
cbb
3
-type cytochrome PA1557.
CO
2
-Responsive Expression and Gene Organization of Three Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase Enzymes and Carboxysomes in
Hydrogenovibrio marinus
Strain MH-110
Authors: Yoshizawa Yoichi , Toyoda Koichi , Arai Hiroyuki , Ishii Masaharu , Igarashi Yasuo
Published: August 2004

Hydrogenovibrio marinus
strain MH-110, an obligately lithoautotrophic hydrogen-oxidizing bacterium, fixes CO
2
by the Calvin-Benson-Bassham cycle. Strain MH-110 possesses three different sets of genes for ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO): CbbLS-1 and CbbLS-2, which belong to form I (L
8
S
8
), and CbbM, which belongs to form II (L
x
). In this paper, we report that the genes for CbbLS-1 (
cbbLS-1
) and CbbM (
cbbM
) are both followed by the
cbbQO
genes and preceded by the
cbbR
genes encoding LysR-type regulators. In contrast, the gene for CbbLS-2 (
cbbLS-2
) is followed by genes encoding carboxysome shell peptides. We also characterized the three RubisCOs in vivo by examining their expression profiles in environments with different CO
2
availabilities. Immunoblot analyses revealed that when strain MH-110 was cultivated in 15% CO
2
, only the form II RubisCO, CbbM, was expressed. When strain MH-110 was cultivated in 2% CO
2
, CbbLS-1 was expressed in addition to CbbM. In the 0.15% CO
2
culture, the expression of CbbM decreased and that of CbbLS-1 disappeared, and CbbLS-2 was expressed. In the atmospheric CO
2
concentration of approximately 0.03%, all three RubisCOs were expressed. Transcriptional analyses of mRNA by reverse transcription-PCR showed that the regulation was at the transcriptional level. Electron microscopic observation of MH-110 cells revealed the formation of carboxysomes in the 0.15% CO
2
concentration. The results obtained here indicate that strain MH-110 adapts well to various CO
2
concentrations by using different types of RubisCO enzymes.
Identification ofLactobacillus plantarumGenes That Are Induced in the Gastrointestinal Tract of Mice
Authors: Bron Peter A. , Grangette Corinne , Mercenier Annick , de Vos Willem M. , Kleerebezem Michiel
Published: August 2004

Lactobacillus plantarumis a flexible and versatile microorganism that inhabits a variety of environmental niches, including the human gastrointestinal (GI) tract. Moreover, this lactic acid bacterium can survive passage through the human or mouse stomach in an active form. To investigate the genetic background of this persistence, resolvase-based in vivo expression technology (R-IVET) was performed inL. plantarumWCFS1 by using the mouse GI tract as a model system. This approach identified 72L. plantarumgenes whose expression was induced during passage through the GI tract as compared to laboratory media. Nine of these genes encode sugar-related functions, including ribose, cellobiose, sucrose, and sorbitol transporter genes. Another nine genes encode functions involved in acquisition and synthesis of amino acids, nucleotides, cofactors, and vitamins, indicating their limited availability in the GI tract. Four genes involved in stress-related functions were identified, reflecting the harsh conditions thatL. plantarumencounters in the GI tract. The four extracellular protein encoding genes identified could potentially be involved in interaction with host specific factors. The rest of the genes are part of several functionally unrelated pathways or encode (conserved) hypothetical proteins. Remarkably, a large number of the functions or pathways identified here have previously been identified in pathogens as being important in vivo during infection, strongly suggesting that survival rather than virulence is the explanation for the importance of these genes during host residence.