bluuebunny/crossref_metadata_2025 huggingface dataset:
Practitioner Review: Assessment and Management of Somatisation in Childhood and Adolescence: A Practical Perspective
Authors: Garralda M. Elena
Published: August 2003

The assessment and treatment of somatisation in childhood require explicit recognition that many families frequently hold strong belief in the presence of physical disorders. Engaging the family, recognising and focusing on their beliefs and concerns, and paediatric/psychiatric liaison are usually required. Our knowledge on the management of children with somatisation is largely based on clinical reports but a number of open trials and methodologically increasingly stronger studies show that somatisation can respond to family treatments involving cognitive‐behavioural techniques as well as to sensitive, psychologically sound advice by paediatricians. Antidepressants should be considered when there are comorbid mood disorders.
Attention‐Deficit/Hyperactivity Disorder and Scholastic Achievement: A Model of Dual Developmental Pathways
Authors: Rapport Mark D. , Scanlan Sean W. , Denney Colin B.
Published: August 2003

A conceptual model has recently been hypothesized in which parallel but correlated developmental pathways exist for attention deficit behaviors and conduct problems. An important component of this model suggests that attention deficit behaviors are related to later scholastic underachievement, whereas conduct problems are unrelated to scholastic underachievement except by their common correlation with attention deficit and intelligence. The present study replicated the general model using a cross‐sectional sample of 325 children, and examined whether hypothesized dual pathways (behavioral and cognitive) better account for the relationship between attention deficit, intelligence, and later scholastic achievement. Results of the structural equation modeling analysis were consistent with the hypothesized dual pathway model and suggest that school behavior and select cognitive abilities serve as important mediators between attention deficit, intelligence, and later scholastic achievement. Implications of these results for understanding the developmental trajectory of children with attention deficit and general theoretical models of ADHD are discussed.
Parents Anticipating Misbehaviour: An Observational Study of Strategies Parents Use to Prevent Conflict with Behaviour Problem Children
Authors: Gardner Frances E. M. , Sonuga‐Barke Edmund J. S. , Sayal Kapil
Published: August 2003

Research on the role of parenting styles in the development of disruptive behaviour problems has focused primarily on how parents handle conflict once it has occurred. This home observational study examined strategies used by 52 mothers to prevent conflict with 3‐year‐olds. It was predicted that mothers of children with behaviour problems would use fewer “positive” strategies to resolve conflict, and would use reactive rather than pre‐emptive strategies. Results showed frequency of positive strategies did not differ between the groups. Mothers of children with behaviour problems were less likely to use pre‐emptive, and more likely to use reactive, strategies. Further analysis showed child conduct problems, rather than other characteristics, best discriminated pre‐emptive from reactive strategy users. Follow‐up of a subsample found that reactive strategies at age 3 predicted age 5 behaviour problems, even after controlling for age 3 behaviour problems.
Executive Functions and Physical Aggression after Controlling for Attention Deficit Hyperactivity Disorder, General Memory, and IQ
Authors: Séguin Jean R. , Boulerice Bernard , Harden Philip W. , Tremblay Richard E. , Pihl Robert O.
Published: August 2003

This study examined the role of ADHD in the association between physical aggression and two types of executive functions. Boys received a cognitive‐neuropsychological test battery over the ages of 13, 14, and 15 years. Diagnostic Interview Schedule for Children (DISC 2.25) data were collected from the boys and one parent between ages 14 and 16, and an IQ estimate was obtained at age 15. Three groups, differing in stability and level of physical aggression since kindergarten, were formed: Stable Aggressive, Unstable Aggressive, and Nonaggressive. Composite scores of validated executive function tests of working memory representing subjective ordering and conditional association learning were formed. A MANCOVA (N= 149) using ADHD status, teacher‐rated negative emotionality, general memory abilities, and IQ as covariates was performed on the two composite scores. ADHD and teacher‐rated emotionality did not provide significant adjustment to the dependent variables. Number of ADHD symptoms was negatively associated only with general memory and IQ. General memory contributed significantly to adjusting for conditional association test scores. Group differences indicated lower conditional association scores for Unstable Aggressive boys relative to the other groups. Both IQ and general memory abilities interacted with subjective ordering within the groups. Specifically, Stable Aggressive boys performed poorly on this measure and did not benefit from increases in IQ whereas Nonaggressive boys performed best and were not disadvantaged by lower general memory abilities. This suggests a relationship exists between aspects of working memory and a history of physical aggression regardless of ADHD and IQ.
Effects of Poverty on Academic Failure and Delinquency in Boys: A Change and Process Model Approach
Authors: Pagani Linda , Boulerice Bernard , Vitaro Frank , Tremblay Richard E.
Published: August 2003

Using data from the Montreal Longitudinal‐Experimental Study, we examined the impact of poverty (and its correlate, family configuration status) on academic placement and self‐reported delinquency in boys at age 16. We then investigated whether the relation between family economic hardship and antisocial behaviour is direct or indirect by considering the value of parenting practices and academic failure as process variables in the model. Data included official records, and parent, teacher, and self‐reports. The temporal intensity of poverty was classified into five categories: never‐poor; always‐poor; poor‐earlier ; poor‐later ; and transitory‐poverty. Family configuration status was classified by both temporal characteristics and number of marital transitions: intact‐family ; short‐term‐single; long‐term‐single; short‐term‐remarried; long‐term‐remarried; and multiple‐marital‐transitions. Results revealed that when maternal education and early childhood behaviour were controlled, poverty had an effect on both academic failure and extreme delinquency. This effect was independent of family configuration status. Although they both significantly predicted extreme delinquency on their own, academic failure and parental supervision did not mediate the relationship between poverty and delinquency. Divorce increased the risk of theft and fighting at age 16, regardless of financial hardship. Parental supervision only helped explain the effects of divorce on boys' fighting.
Behavior Problems and Mental Health Contacts in Adopted, Foster, and Nonadopted Children
Authors: Brand Ann E. , Brinich Paul M.
Published: August 2003

The implications of adoption for the emotional and behavioral adjustment of children have been an issue in child welfare for many years. Past research has suggested that adopted children are over‐represented in mental health settings. In addition, some studies have suggested that adopted and nonadopted children differ on measures of social, emotional, behavioral, and cognitive functioning. The current study used data from a large, representative sample in the United States to examine whether adopted children are more likely to have had mental health contacts or emotional or behavioral problems than nonadopted children. Age of placement in the adoptive home was examined as a variable contributing to the adjustment of adopted children. Results suggest that adopted and foster children are more likely to have mental health contacts than nonadopted children. Results are mixed regarding whether adopted and foster children have more behavior problems than nonadopted children. However, significant differences between adopted, foster, and nonadopted children disappeared when a small group of influential cases were removed. This suggests that the differences seen between the groups reflect a small number of cases and are not representative of the groups of adoptees and foster children as a whole. The vast majority of adopted children showed patterns of behavior problems similar to those of nonadopted children. These results are discussed in relation to the past literature and areas for future research.
The Orphans of Eritrea: A Five‐year Follow‐up Study
Authors: Wolff Peter H. , Fesseha Gebremeskel
Published: August 2003

A group of 4–7‐year‐old war orphans were examined for the first time while living in an institution (the Solomuna Orphanage) during a protracted war between Eritrea and Ethiopia. At that time, they were compared to a group of refugee children living in a nearby camp with one or both parents. The orphans exhibited significantly more behavioral symptoms than the refugee children, but performed the cognitive tests at a more advanced level. Five years later, the orphans were re‐examined; and they were compared to unaccompanied 9–12‐year‐children living in one of two residential settings that differed qualitatively in their social climate, principles of child care, and patterns of staff‐child interactions. Although the severity of their behavioral symptoms had diminished, the orphans still exhibited many symptoms of emotional distress. On the other hand, they performed the cognitive measures as well as, or better than, unaccompanied children who had been protected from the terrors of war. The cross‐sectional comparisons indicated that a residential setting that respects the individuality of children and promotes their close personal ties with at least one staff member can ameliorate many of the more serious psychological sequelae of having lost both parents and being exposed to the physical dangers of the war. The implications for war orphans in other Third World countries are discussed.
Mental Health in International Adoptees as Teenagers and Young Adults. An Epidemiological Study
Authors: Cederblad Marianne , Höök Börje , Irhammar Malin , Mercke Ann‐Mari
Published: August 2003

Sweden has now around 38,000 individuals who have been adopted from other countries. Most often they are transracially adopted and have a different appearance from their new parents—“visible ” adoptions. This study was made to explore the mental health of a teenager/young adult group that arrived with their families in the southernmost county of Sweden between 1970 and 1977. They were placed through the largest Swedish adoption agency at that time. One hundred and forty‐seven families and their 211 adopted children, who were 13 years of age or older at the time of the investigation, were interviewed in their homes. CBCL, SCL‐90, a self‐esteem questionnaire, and two family relations inventories were also completed. Compared to nonadopted Swedish young persons of the same ages, who had been investigated with the same inventories in earlier epidemiological studies, the adoptees had as good mental health. The adoptees also reported good self‐esteem. The pre‐adoption conditions were more important than the age of arrival in itself for the risk of later maladaptation. Family relations, various aspects of identity, and peer relations explained much of the variance of mental health and self‐esteem. Those who were most engaged in questions about their identity and felt mostly non‐Swedish had more behaviour problems. The association, however, between the factor “ Identity ” and the mental health variables approached zero for the older subjects (18–27 years of age). The majority (about 90%) of the adoptees felt mostly Swedish. Seventy per cent didn't feel any connection to their country of origin.
Parents' Judgements About Young Children's Problems: Why Mothers and Fathers Might Disagree Yet Still Predict Later Outcomes
Authors: Hay Dale F. , Pawlby Susan , Sharp Deborah , Schmücker Gesine , Mills Alice , Allen Helen , Kumar R.
Published: August 2003

Correlates of parents' ratings of behavioural problems were explored in a sample of 93 British families, in which mothers and fathers rated their children at the time of the fourth birthday on the Achenbach Child Behavior Checklist. As in other samples, there was moderate convergence in mothers' and fathers' total problem scores, but also signs that they were reporting different sorts of problems linked to different influences. The father's rating was primarily associated with the child's cognitive ability. The mother's rating was primarily affected by her own mental state and view of her marriage. The father's but not the mother's rating provided unique information that predicted teachers' reports of the children's problems 7 years later. In general, parents' ratings of preschool children's problems reflect particular informants' perspectives on family life.
The Socioemotional Development of 5‐year‐old Children of Postnatally Depressed Mothers
Authors: Murray Lynne , Sinclair Dana , Cooper Peter , Ducournau Pierre , Turner Patricia , Stein Alan
Published: August 2003

A community sample of depressed and well mothers, recruited at 2 months postpartum and assessed through to 18 months, was followed up at 5 years. The quality of mother‐child interactions was assessed, as was the children's behavioural and social adjustment, using maternal reports and observations of child behaviour during free play at school. Several aspects of child outcome were found to be associated with postnatal depression, even when taking account of current adverse circumstances (maternal depression and parental conflict). These included the child's behaviour with the mother, the presence of behavioural disturbance at home, and the content and social patterning of play at school. These associations with postnatal depression were independent of the child's gender. The child's relationship with the mother appeared to be mediated by the quality of infant attachment at 18 months. The mother's behaviour with her child was more affected by current difficulties, in particular by conflict with the child's father. Together these findings suggest that, while maternal behaviour varies with changing circumstances, exposure to maternal depression in the early postpartum months may have an enduring influence on child psychological adjustment.
Exploring the Covariation between Anxiety and Depression Symptoms: A Genetic Analysis of the Effects of Age and Sex
Authors: Eley Thalia C. , Stevenson Jim
Published: August 2003

Self‐reported anxiety and depression symptoms in children and adolescents have been shown to be heritable, and are also highly correlated. Furthermore, there have been indications in the literature of sex and age differences in the aetiologies of these two types of symptoms. This study set out to ascertain to what extent the genetic and environmental factors that influence anxiety symptoms also influence depression symptoms, and whether these are the same in children and adolescents, and males and females. Four hundred and ninety pairs of twins aged 8 to 16 years completed the Children's Depression Inventory and the Trait scale of the State‐Trait Anxiety Inventory for Children. There were significant effects of age and sex on the variance in and covariance between these two types of symptom. Bivariate genetic analyses of the measures indicated that the genetic influences on anxiety and depression were shared for all four groups, a finding that has been consistently demonstrated for adults.
Are Individuals with Autism and Asperger's Syndrome Susceptible to Visual Illusions ?
Authors: Ropar Danielle , Mitchell Peter
Published: August 2003

A recent finding that individuals with autism are not susceptible to illusions has been explained by Happé (1996) as a sign of “weak central coherence” at lower levels of processing. We investigated the phenomenon with a more sophisticated measure. In Experiment 1, individuals with autism, Asperger's syndrome, moderate learning difficulties, and typical development adjusted certain comparison lines and circles to make them appear to be the same size in four visual illusions. With a minor exception, the participants with autism and Asperger's syndrome evinced a systematic bias in their judgements in the illusion condition. The extent of this was no different from control participants. In a second experiment, a similar finding was obtained in a task where participants made verbal judgements about the stimuli. The results suggest that lower‐level coherence in visual processing in autism is intact.
Proteomic Analysis of Wild-Type
Sinorhizobium meliloti
Responses to
N
-Acyl Homoserine Lactone Quorum-Sensing Signals and the Transition to Stationary Phase
Authors: Chen Hancai , Teplitski Max , Robinson Jayne B. , Rolfe Barry G. , Bauer Wolfgang D.
Published: August 2003

Proteome analysis revealed that two long-chain
N
-acyl homoserine lactones (AHLs) produced by
Sinorhizobium meliloti
1021 induced significant differences in the accumulation of more than 100 polypeptides in early-log-phase cultures of the wild type. Fifty-six of the corresponding proteins have been identified by peptide mass fingerprinting. The proteins affected by addition of these two AHLs had diverse functions in carbon and nitrogen metabolism, energy cycles, metabolite transport, DNA synthesis, and protein turnover. Two hours of exposure to 3-oxo-C
16:1
-homoserine lactone (3-oxo-C
16:1
-HL) affected the accumulation of 40 of the 56 identified proteins, whereas comparable exposure to C
14
-HL affected 13 of the 56 proteins. Levels of four proteins were affected by both AHLs. Exposure to 3-oxo-C
16:1
-HL for 8 h affected the accumulation of 17 proteins, 12 of which had reduced accumulation. Of the 80 proteins identified as differing in accumulation between early-log- and early-stationary-phase cultures, only 13 were affected by exposure to 3-oxo-C
16:1
-HL or C
14
-HL. These results provide a foundation for future studies of the functions regulated by AHL quorum sensing in
S. meliloti
and help to establish proteomic analysis as a powerful global approach to the identification of quorum-sensing regulatory patterns in wild-type bacteria.
Open Reading Frame
all0601
from
Anabaena
sp. Strain PCC 7120 Represents a Novel Gene,
cnaT
, Required for Expression of the Nitrate Assimilation
nir
Operon
Authors: Frías José E. , Herrero Antonia , Flores Enrique
Published: August 2003

Expression of the nitrate assimilation
nir
operon in the filamentous, heterocyst-forming cyanobacterium
Anabaena
sp. strain PCC 7120 requires the action of both the global nitrogen control transcription factor NtcA and the pathway-specific transcriptional regulator NtcB. In the genome of this cyanobacterium, the
ntcB
gene is found in a cluster of genes located in the complementary strand, upstream from the
nir
operon. Just downstream of
ntcB
, there is an open reading frame,
all0601
(previously designated
orf356
and now designated the
cnaT
gene), that putatively encodes a protein similar to proteins with glycosyl transferase activity and that is also present clustered together with
ntcB
homologues or nitrate assimilation structural genes in other cyanobacterial genomes. An insertional mutant of
cnaT
was generated and found to be unable to assimilate nitrate, although it could use ammonium or dinitrogen as a source of nitrogen for growth. In the mutant, under derepression conditions,
nir
operon mRNA (as determined by RNA-DNA hybridization and primer extension analysis) and enzymes of the nitrate reduction system (i.e., nitrate reductase and nitrite reductase) were expressed at low or undetectable levels. Inactivation of
cnaT
did not impair expression of
ntcB
, and expression of
cnaT
itself was constitutive and regulated by neither NtcA nor NtcB. Regulation of expression of the
nir
operon in
Anabaena
sp. strain PCC 7120 by CnaT and the previously described regulatory elements, NtcA and NtcB, is discussed.
Control of SXT Integration and Excision
Authors: Burrus Vincent , Waldor Matthew K.
Published: August 2003

The
Vibrio cholerae
SXT element is a conjugative self-transmissible chromosomally integrating element that encodes resistance to multiple antibiotics. SXT integrates in a site-specific fashion at
prfC
and excises from the chromosome to form a circular but nonreplicative extrachromosomal form. Both chromosomal integration and excision depend on an SXT-encoded recombinase, Int. Here we found that Int is necessary and sufficient for SXT integration and that
int
expression in recipient cells requires the SXT activators SetC and SetD. Although no
xis
-like gene was annotated in the SXT genome, Int was not sufficient to mediate efficient SXT chromosomal excision. We identified a novel SXT Xis that seems to function as a recombination directionality factor (RDF), facilitating SXT excision and inhibiting SXT integration. Although unrelated to any previously characterized RDF, Xis is similar to five hypothetical proteins that together may constitute a new family of RDFs. Using real-time quantitative PCR assays to study SXT excision from the chromosome, we determined that while SXT excision is required for SXT transfer, the percentage of cells containing an excised circular SXT does not appear to be a major factor limiting SXT transfer; i.e., we found that most cells harboring an excised circular SXT molecule do not act as SXT donors. In the absence of
prfC
, SXT integrated into several secondary attachment sites but preferentially into the 5′ end of
pntB
. SXT excision and transfer from a donor containing
pntB
::SXT were reduced, suggesting that the SXT integration site may also influence the element's transmissibility.
Composition, Acquisition, and Distribution of the Vi Exopolysaccharide-Encoding
Salmonella enterica
Pathogenicity Island SPI-7
Authors: Pickard Derek , Wain John , Baker Stephen , Line Alexandra , Chohan Sonia , Fookes Maria , Barron Andrew , Ó Gaora Peadar , Chabalgoity José A. , Thanky Niren , Scholes Christoph , Thomson Nicholas , Quail Michael , Parkhill Julian , Dougan Gordon
Published: August 2003

Vi capsular polysaccharide production is encoded by the
viaB
locus, which has a limited distribution in
Salmonella enterica
serovars. In
S. enterica
serovar Typhi,
viaB
is encoded on a 134-kb pathogenicity island known as SPI-7 that is located between partially duplicated tRNA

pheU

sites. Functional and bioinformatic analysis suggests that SPI-7 has a mosaic structure and may have evolved as a consequence of several independent insertion events. Analysis of
viaB
-associated DNA in Vi-positive
S. enterica
serovar Paratyphi C and
S. enterica
serovar Dublin isolates revealed the presence of similar SPI-7 islands. In
S. enterica
serovars Paratyphi C and Dublin, the SopE bacteriophage and a 15-kb fragment adjacent to the intact tRNA

pheU

site were absent. In
S. enterica
serovar Paratyphi C only, a region encoding a type IV pilus involved in the adherence of
S. enterica
serovar Typhi to host cells was missing. The remainder of the SPI-7 islands investigated exhibited over 99% DNA sequence identity in the three serovars. Of 30 other
Salmonella
serovars examined, 24 contained no insertions at the equivalent tRNA

pheU

site, 2 had a 3.7-kb insertion, and 4 showed sequence variation at the tRNA

pheU

-
phoN
junction, which was not analyzed further. Sequence analysis of the SPI-7 region from
S. enterica
serovar Typhi strain CT18 revealed significant synteny with clusters of genes from a variety of saprophytic bacteria and phytobacteria, including
Pseudomonas aeruginosa
and
Xanthomonas axonopodis
pv. citri. This analysis suggested that SPI-7 may be a mobile element, such as a conjugative transposon or an integrated plasmid remnant.
Membrane Localization of Motility, Signaling, and Polyketide Synthetase Proteins in
Myxococcus xanthus
Authors: Simunovic Vesna , Gherardini Frank C. , Shimkets Lawrence J.
Published: August 2003

Myxococcus xanthus
cells coordinate cellular motility, biofilm formation, and development through the use of cell signaling pathways. In an effort to understand the mechanisms underlying these processes, the inner membrane (IM) and outer membrane (OM) of strain DK1622 were fractionated to examine protein localization. Membranes were enriched from spheroplasts of vegetative cells and then separated into three peaks on a three-step sucrose gradient. The high-density fraction corresponded to the putative IM, the medium-density fraction corresponded to a putative hybrid membrane (HM), and the low-density fraction corresponded to the putative OM. Each fraction was subjected to further separation on discontinuous sucrose gradients, which resulted in discrete protein peaks for each major fraction. The purity and origin of each peak were assessed by using succinate dehydrogenase (SDH) activity as the IM marker and reactivities to lipopolysaccharide core and O-antigen monoclonal antibodies as the OM markers. As previously reported, the OM markers localized to the low-density membrane fractions, while SDH localized to high-density fractions. Immunoblotting was used to localize important motility and signaling proteins within the protein peaks. CsgA, the C-signal-producing protein, and FibA, a fibril-associated protease, were localized in the IM (density, 1.17 to 1.24 g cm
−3
). Tgl and Cgl lipoproteins were localized in the OM, which contained areas of high buoyant density (1.21 to 1.24 g cm
−3
) and low buoyant density (1.169 to 1.171 g cm
−3
). FrzCD, a methyl-accepting chemotaxis protein, was predominantly located in the IM, although smaller amounts were found in the OM. The HM peaks showed twofold enrichment for the type IV pilin protein PilA, suggesting that this fraction contained cell poles. Two-dimensional polyacrylamide gel electrophoresis revealed the presence of proteins that were unique to the IM and OM. Characterization of proteins in an unusually low-density membrane peak (1.072 to 1.094 g cm
−3
) showed the presence of Ta-1 polyketide synthetase, which synthesizes the antibiotic myxovirescin A.
Coordinate Regulation of the
Escherichia coli
Formate Dehydrogenase
fdnGHI
and
fdhF
Genes in Response to Nitrate, Nitrite, and Formate: Roles for NarL and NarP
Authors: Wang Henian , Gunsalus Robert P.
Published: August 2003

Escherichia coli
possesses three distinct formate dehydrogenase enzymes encoded by the
fdnGHI
,
fdhF
, and
fdoGHI
operons. To examine how two of the formate dehyrogenase operons (
fdnGHI
and
fdhF
) are expressed anaerobically in the presence of low, intermediate, and high levels of nitrate, nitrite, and formate, chemostat culture techniques were employed with
fdnG-lacZ
and
fdhF-lacZ
reporter fusions. Complementary patterns of gene expression were seen. Optimal
fdhF-lacZ
expression occurred only at low to intermediate levels of nitrate, while high nitrate levels caused up to 10-fold inhibition of gene expression. In contrast,
fdnG-lacZ
expression was induced 25-fold in the presence of intermediate to high nitrate concentrations. Consistent with prior reports, NarL was able to induce
fdnG-lacZ
expression. However, NarP could not induce expression; rather, it functioned as an antagonist of
fdnG-lacZ
expression under low-nitrate conditions (i.e., it was a negative regulator). Nitrite, a reported signal for the Nar sensory system, was unable to stimulate or suppress expression of either formate dehydrogenase operon via NarL and NarP. The different gene expression profiles of the alternative formate dehydrogenase operons suggest that the two enzymes have complementary physiological roles under environmental conditions when nitrate and formate levels are changing. Revised regulatory schemes for NarL- and NarP-dependent nitrate control are presented for each operon.
Protein Content of Polyhedral Organelles Involved in Coenzyme B
12
-Dependent Degradation of 1,2-Propanediol in
Salmonella enterica
Serovar Typhimurium LT2
Authors: Havemann Gregory D. , Bobik Thomas A.
Published: August 2003

Salmonella enterica
forms polyhedral organelles during coenzyme B
12
-dependent growth on 1,2-propanediol (1,2-PD). Previously, these organelles were shown to consist of a protein shell partly composed of the PduA protein, the majority of the cell's B
12
-dependent diol dehydratase, and additional unidentified proteins. In this report, the polyhedral organelles involved in B
12
-dependent 1,2-PD degradation by
S. enterica
were purified by a combination of detergent extraction and differential and density gradient centrifugation. The course of the purification was monitored by electron microscopy and gel electrophoresis, as well as enzymatic assay of B
12
-dependent diol dehydratase. Following one- and two-dimensional gel electrophoresis of purified organelles, the identities and relative abundance of their constituent proteins were determined by N-terminal sequencing, protein mass fingerprinting, Western blotting, and densitometry. These analyses indicated that the organelles consisted of at least 15 proteins, including PduABB′CDEGHJKOPTU and one unidentified protein. Seven of the proteins identified (PduABB′JKTU) have some sequence similarity to the shell proteins of carboxysomes (a polyhedral organelle involved in autotrophic CO
2
fixation), suggesting that the
S. enterica
organelles and carboxysomes have a related multiprotein shell. In addition,
S. enterica
organelles contained four enzymes: B
12
-dependent diol dehydratase, its putative reactivating factor, aldehyde dehydrogenase, and ATP cob(I)alamin adenosyltransferase. This complement of enzymes indicates that the primary catalytic function of the
S. enterica
organelles is the conversion of 1,2-PD to propionyl coenzyme A (which is consistent with our prior proposal that the
S. enterica
organelles function to minimize aldehyde toxicity during growth on 1,2-PD). The possibility that similar protein-bound organelles may be more widespread in nature than currently recognized is discussed.
RtsA and RtsB Coordinately Regulate Expression of the Invasion and Flagellar Genes inSalmonella entericaSerovar Typhimurium
Authors: Ellermeier Craig D. , Slauch James M.
Published: August 2003

Salmonella entericaserovar Typhimurium encounters numerous host environments and defense mechanisms during the infection process. The bacterium responds by tightly regulating the expression of virulence genes. We identified two regulatory proteins, termed RtsA and RtsB, which are encoded in an operon located on an island integrated at tRNAPheUinS. entericaserovar Typhimurium. RtsA belongs to the AraC/XylS family of regulators, and RtsB is a helix-turn-helix DNA binding protein. In a random screen, we identified five RtsA-regulated fusions, all belonging to theSalmonellapathogenicity island 1 (SPI1) regulon, which encodes a type III secretion system (TTSS) required for invasion of epithelial cells. We show that RtsA increases expression of the invasion genes by inducinghilAexpression. RtsA also induces expression ofhilD,hilC, and theinvFoperon. However, induction ofhilAis independent of HilC and HilD and is mediated by direct binding of RtsA to thehilApromoter. The phenotype of anrtsAnull mutation is similar to the phenotype of ahilCmutation, both of which decrease expression of SPI1 genes approximately twofold. We also show that RtsA can induce expression of a SPI1 TTSS effector,slrP, independent of any SPI1 regulatory protein. RtsB represses expression of the flagellar genes by binding to theflhDCpromoter region. Repression of the positive activatorsflhDCdecreases expression of the entire flagellar regulon. We propose that RtsA and RtsB coordinate induction of invasion and repression of motility in the small intestine.
Regulation of Expression of Scaffoldin-Related Genes in
Clostridium thermocellum
Authors: Dror Tali W. , Rolider Adi , Bayer Edward A. , Lamed Raphael , Shoham Yuval
Published: August 2003

Clostridium thermocellum
produces an extracellular multienzyme complex, termed the cellulosome, that allows efficient solubilization of crystalline cellulose. The complex is organized around a large noncatalytic protein subunit, termed CipA or scaffoldin, and is found either free in the supernatant or cell bound. The binding of the complex to the cell is mediated by three cell surface anchoring proteins, OlpB, Orf2p, and SdbA, that interact with the CipA scaffoldin. The transcriptional level of the
olpB
,
orf2
,
sdbA
, and
cipA
genes was determined quantitatively by RNase protection assays in batch and continuous cultures, under carbon and nitrogen limitation. The mRNA level of
olpB
,
orf2
, and
cipA
varied with growth rate, reaching 40 to 60 transcripts per cell under carbon limitation at a low growth rate of 0.04 h
−1
and 2 to 10 transcripts per cell at a growth rate of 0.35 h
−1
in batch culture. The mRNA level of
sdbA
was about three transcripts per cell and was not influenced by growth rate. Primer extension analysis revealed two major transcriptional start sites, at −81 and −50 bp, upstream of the translational start site of the
cipA
gene. The potential promoters exhibited homology to the known sigma factors σ
A
and σ
L
(σ
54
) of
Bacillus subtilis
. Transcription from the σ
L
-like promoter was found under all growth conditions, whereas transcription from the σ
A
-like promoter was significant only under carbon limitation. The overall expression level obtained in the primer extension analysis was in good agreement with the results of the RNase-protection assays.
ClpE from
Lactococcus lactis
Promotes Repression of CtsR-Dependent Gene Expression
Authors: Varmanen Pekka , Vogensen Finn K. , Hammer Karin , Palva Airi , Ingmer Hanne
Published: August 2003

The heat shock response in bacterial cells is characterized by rapid induction of heat shock protein expression, followed by an adaptation period during which heat shock protein synthesis decreases to a new steady-state level. In this study we found that after a shift to a high temperature the Clp ATPase (ClpE) in
Lactococcus lactis
is required for such a decrease in expression of a gene negatively regulated by the heat shock regulator (CtsR). Northern blot analysis showed that while a shift to a high temperature in wild-type cells resulted in a temporal increase followed by a decrease in expression of
clpP
encoding the proteolytic component of the Clp protease complex, this decrease was delayed in the absence of ClpE. Site-directed mutagenesis of the zinc-binding motif conserved in ClpE ATPases interfered with the ability to repress CtsR-dependent expression. Quantification of ClpE by Western blot analysis revealed that at a high temperature ClpE is subjected to ClpP-dependent processing and that disruption of the zinc finger domain renders ClpE more susceptible. Interestingly, this domain resembles the N-terminal region of McsA, which was recently reported to interact with the CtsR homologue in
Bacillus subtilis
. Thus, our data point to a regulatory role of ClpE in turning off
clpP
gene expression following temporal heat shock induction, and we propose that this effect is mediated through CtsR.
Anthranilate Synthase Can Generate Sufficient Phosphoribosyl Amine for Thiamine Synthesis in
Salmonella enterica
Authors: Ramos I. , Downs Diana M.
Published: August 2003

In bacteria, the biosynthetic pathway for the hydroxymethyl pyrimidine moiety of thiamine shares metabolic intermediates with purine biosynthesis. The two pathways branch after the compound aminoimidazole ribotide. Past work has shown that the first common metabolite, phosphoribosyl amine (PRA), can be generated in the absence of the first enzyme in purine biosynthesis, PurF. PurF-independent PRA synthesis is dependent on both strain background and growth conditions. Standard genetic approaches have not identified a gene product singly responsible for PurF-independent PRA formation. This result has led to the hypothesis that multiple enzymes contribute to PRA synthesis, possibly as the result of side products from their dedicated reaction. A mutation that was able to restore PRA synthesis in a
purF gnd
mutant strain was identified and found to map in the gene coding for the TrpD subunit of the anthranilate synthase (AS)-phosphoribosyl transferase (PRT) complex. Genetic analyses indicated that wild-type AS-PRT was able to generate PRA in vivo and that the P362L mutant of TrpD facilitated this synthesis. In vitro activity assays showed that the mutant AS was able to generate PRA from ammonia and phosphoribosyl pyrophosphate. This work identifies a new reaction catalyzed by AS-PRT and considers it in the context of cellular thiamine synthesis and metabolic flexibility.
Mutational Loss of a K
+
and NH
4
+
Transporter Affects the Growth and Endospore Formation of Alkaliphilic
Bacillus pseudofirmus
OF4
Authors: Wei Yi , Southworth Thomas W. , Kloster Hilde , Ito Masahiro , Guffanti Arthur A. , Moir Anne , Krulwich Terry A.
Published: August 2003

A putative transport protein (Orf9) of alkaliphilic
Bacillus pseudofirmus
OF4 belongs to a transporter family (CPA-2) of diverse K
+
efflux proteins and cation antiporters. Orf9 greatly increased the concentration of K
+
required for growth of a K
+
uptake mutant of
Escherichia coli
. The cytoplasmic K
+
content of the cells was reduced, consistent with an efflux mechanism. Orf9-dependent translocation of K
+
in
E. coli
is apparently bidirectional, since ammonium-sensitive uptake of K
+
could be shown in K
+
-depleted cells. The upstream gene product Orf8 has sequence similarity to a subdomain of KTN proteins that are associated with potassium-translocating channels and transporters; Orf8 modulated the transport capacities of Orf9. No Orf9-dependent K
+
(Na
+
)/H
+
antiport activity was found in membrane vesicles. Nonpolar deletion mutants in the
orf9
locus of the alkaliphile chromosome exhibited no K
+
-related phenotype but showed profound phenotypes in medium containing high levels of amine-nitrogen. Their patterns of growth and ammonium content suggested a physiological role for the
orf9
locus in bidirectional ammonium transport. Orf9-dependent ammonium uptake was observed in right-side-out membrane vesicles of the alkaliphile wild type and the mutant with an
orf8
deletion. Uptake was proton motive force dependent and was inhibited by K
+
. Orf9 is proposed to be designated AmhT (ammonium homeostasis). Ammonium homeostasis is important in high-amine-nitrogen settings and is particularly crucial at high pH since cytosolic ammonium accumulation interferes with cytoplasmic pH regulation. Endospore formation in amino-acid-rich medium was significantly defective and germination was modestly defective in the
orf9
and
orf7
-
orf10
deletion mutants.
Cyclic AMP Receptor Protein-Dependent Activation of the
Escherichia coli acs
P2 Promoter by a Synergistic Class III Mechanism
Authors: Beatty Christine M. , Browning Douglas F. , Busby Stephen J. W. , Wolfe Alan J.
Published: August 2003

The cyclic AMP receptor protein (CRP) activates transcription of the
Escherichia coli acs
gene, which encodes an acetate-scavenging enzyme required for fitness during periods of carbon starvation. Two promoters direct transcription of
acs
, the distal
acs
P1 and the proximal
acs
P2. In this study, we demonstrated that
acs
P2 can function as the major promoter and showed by in vitro studies that CRP facilitates transcription by “focusing” RNA polymerase to
acs
P2. We proposed that CRP activates transcription from
acs
P2 by a synergistic class III mechanism. Consistent with this proposal, we showed that CRP binds two sites, CRP I and CRP II. Induction of
acs
expression absolutely required CRP I, while optimal expression required both CRP I and CRP II. The locations of these DNA sites for CRP (centered at positions −69.5 and −122.5, respectively) suggest that CRP interacts with RNA polymerase through class I interactions. In support of this hypothesis, we demonstrated that
acs
transcription requires the surfaces of CRP and the C-terminal domain of the α subunit of RNA polymerase holoenzyme (α-CTD), which is known to participate in class I interactions: activating region 1 of CRP and the 287, 265, and 261 determinants of the α-CTD. Other surface-exposed residues in the α-CTD contributed to
acs
transcription, suggesting that the α-CTD may interact with at least one protein other than CRP.
Determination of the InvE Binding Site Required for Expression of IpaB of the
Shigella sonnei
Virulence Plasmid: Involvement of a ParB BoxA-Like Sequence
Authors: Taniya Takayuki , Mitobe Jiro , Nakayama Shu-ichi , Mingshan Qi , Okuda Kenji , Watanabe Haruo
Published: August 2003

The InvE protein positively regulates the expression of virulence genes
ipaBCD
in
Shigella sonnei
. The InvE has significant homology with ParB of plasmid P1, which is known as a plasmid partitioning factor with DNA binding ability. Although the DNA binding activity of InvE has been predicted, it is not known whether the DNA binding activity is necessary for type III secretion system-associated gene expression. In this study, we determined the transcription start site of the
icsB-ipaBCD
operon (
ipa
operon) and constructed a series of deletions of the
icsB
promoter region in the
Escherichia coli
K-12 background. The deletion study revealed that an 86-bp region upstream of the
icsB
transcription start site was essential for expression of the
ipa
operon, where the ParB binding motif (ParB BoxA-like sequence) was observed. Purified glutathione
S
-transferase-InvE fusion protein bound directly to the −93 to −54 region (designating the
icsB
transcription start site as nucleotide +1) containing the ParB BoxA-like sequence. These results indicated that InvE bound directly to the promoter region.
Role of RopB in Growth Phase Expression of the SpeB Cysteine Protease ofStreptococcus pyogenes
Authors: Neely Melody N. , Lyon William R. , Runft Donna L. , Caparon Michael
Published: August 2003

The Rgg family of transcription regulators is widely distributed among gram-positive bacteria; however, how the members of this family control transcription is poorly understood. In the pathogenStreptococcus pyogenes, the Rgg family member RopB is required for transcription of the gene that encodes the secreted SpeB cysteine protease. Expression of the protease follows distinct kinetics that involves control of transcription in response to the growth phase. In this study, the contribution of RopB to growth phase control was examined. The gene encoding the protease (speB) andropBare transcribed divergently from a 940-bp intergenic region. Primer extension analyses, in conjunction with reporter fusion studies, revealed that the major region controlling the transcription of bothspeBandropBis adjacent toropBand that the promoters for the two genes likely overlap. Furthermore, it was found that RopB is a DNA-binding protein that specifically binds to sequences in this control region. The interrelationship betweenropBandspeBexpression was further reflected in the observation that transcription ofropBitself is subject to growth phase control. However, while expression ofropBfrom a promoter expressed during the early logarithmic phase of growth could complement aropBdeletion mutant, ectopic expression ofropBdid not uncouple the expression ofspeBfrom its growth phase signal. These data implicate other factors in growth phase control and suggest that regulation ofropBexpression itself is not the central mechanism of control.
Characterization of an Exo-β-
d
-Glucosaminidase Involved in a Novel Chitinolytic Pathway from the Hyperthermophilic Archaeon
Thermococcus kodakaraensis
KOD1
Authors: Tanaka Takeshi , Fukui Toshiaki , Atomi Haruyuki , Imanaka Tadayuki
Published: August 2003

We previously clarified that the chitinase from the hyperthermophilic archaeon
Thermococcus kodakaraensis
KOD1 produces diacetylchitobiose (GlcNAc
2
) as an end product from chitin. Here we sought to identify enzymes in
T. kodakaraensis
that were involved in the further degradation of GlcNAc
2
. Through a search of the
T. kodakaraensis
genome, one candidate gene identified as a putative β-glycosyl hydrolase was found in the near vicinity of the chitinase gene. The primary structure of the candidate protein was homologous to the β-galactosidases in family 35 of glycosyl hydrolases at the N-terminal region, whereas the central region was homologous to β-galactosidases in family 42. The purified protein from recombinant
Escherichia coli
clearly showed an exo-β-
d
-glucosaminidase (GlcNase) activity but not β-galactosidase activity. This GlcNase (GlmA

Tk

), a homodimer of 90-kDa subunits, exhibited highest activity toward reduced chitobiose at pH 6.0 and 80°C and specifically cleaved the nonreducing terminal glycosidic bond of chitooligosaccharides. The GlcNase activity was also detected in
T. kodakaraensis
cells, and the expression of GlmA

Tk

was induced by GlcNAc
2
and chitin, strongly suggesting that GlmA

Tk

is involved in chitin catabolism in
T. kodakaraensis.
These results suggest that
T. kodakaraensis
, unlike other organisms, possesses a novel chitinolytic pathway where GlcNAc
2
from chitin is first deacetylated and successively hydrolyzed to glucosamine. This is the first report that reveals the primary structure of GlcNase not only from an archaeon but also from any organism.
The SopEΦ Phage Integrates into thessrAGeneof Salmonella entericaSerovar Typhimurium A36 and Is Closely Related to the Fels-2 Prophage
Authors: Pelludat Cosima , Mirold Susanne , Hardt Wolf-Dietrich
Published: August 2003

Salmonellaspp. are enteropathogenic gram-negative bacteria that use a large array of virulence factors to colonize the host, manipulate host cells, and resist the host's defense mechanisms. Even closely relatedSalmonellastrains have different repertoires of virulence factors. Bacteriophages contribute substantially to this diversity. There is increasing evidence that the reassortment of virulence factor repertoires by converting phages like the GIFSY phages and SopEΦ may represent an important mechanism in the adaptation ofSalmonellaspp. to specific hosts and to the emergence of new epidemic strains. Here, we have analyzed in more detail SopEΦ, a P2-like phage fromSalmonella entericaserovar Typhimurium DT204 that encodes the virulence factor SopE. We have cloned and characterized the attachment site (att) of SopEΦ and found that its 47-bp core sequence overlaps the 3′ terminus of thessrAgene of serovar Typhimurium. Furthermore, we have demonstrated integration of SopEΦ into the clonedattBsite of serovar Typhimurium A36. Sequence analysis of the plasmid-borne prophage revealed that SopEΦ is closely related to (60 to 100% identity over 80% of the genome) but clearly distinct from the Fels-2 prophage of serovar Typhimurium LT2 and from P2-like phages in the serovar Typhi CT18 genome. Our results demonstrate that there is considerable variation among the P2-like phages present in closely relatedSalmonellaspp.