bluuebunny/crossref_metadata_2025 huggingface dataset:
Regulation of the Tryptophan Biosynthetic Genes in
Bacillus halodurans
: Common Elements but Different Strategies than Those Used by
Bacillus subtilis
Authors: Szigeti Reka , Milescu Mirela , Gollnick Paul
Published: January 2004

In
Bacillus subtilis
, an RNA binding protein called TRAP regulates both transcription and translation of the tryptophan biosynthetic genes.
Bacillus halodurans
is an alkaliphilic
Bacillus
species that grows at high pHs. Previous studies of this bacterium have focused on mechanisms of adaptation for growth in alkaline environments. We have characterized the regulation of the tryptophan biosynthetic genes in
B. halodurans
and compared it to that in
B. subtilis. B. halodurans
encodes a TRAP protein with 71% sequence identity to the
B. subtilis
protein. Expression of anthranilate synthetase, the first enzyme in the pathway to tryptophan, is regulated significantly less in
B. halodurans
than in
B. subtilis
. Examination of the control of the
B. halodurans trpEDCFBA
operon both in vivo and in vitro shows that only transcription is regulated, whereas in
B. subtilis
both transcription of the operon and translation of
trpE
are controlled. The attenuation mechanism that controls transcription in
B. halodurans
is similar to that in
B. subtilis
, but there are some differences in the predicted RNA secondary structures in the
B. halodurans trp
leader region, including the presence of a potential anti-antiterminator structure. Translation of
trpG
, which is within the folate operon in both bacilli, is regulated similarly in the two species.
Binding of SycH Chaperone to YscM1 and YscM2 Activates Effector
yop
Expression in
Yersinia enterocolitica
Authors: Cambronne Eric D. , Sorg Joseph A. , Schneewind Olaf
Published: January 2004

Yersinia enterocolitica
transports YscM1 and YscM2 via the type III pathway, a mechanism that is required for the establishment of bacterial infections. Prior to host cell contact, YscM1 and YscM2 exert posttranscriptional regulation to inhibit expression of effector
yop
genes, which encode virulence factors that travel the type III pathway into the cytoplasm of macrophages. Relief from repression has been predicted to occur via the type III secretion of YscM1 and YscM2 into the extracellular medium, resulting in the depletion of regulatory molecules from the bacterial cytoplasm. Using digitonin fractionation and fluorescence microscopy of FlAsH-labeled polypeptides in
Yersinia
-infected cells, we have localized YscM1 and YscM2 within the host cell cytoplasm. Type III injection of YscM1 and YscM2 required the SycH chaperone. Expression of C-terminal fusions of YscM1 and YscM2 to the neomycin phosphotransferase reporter revealed sequences required for regulatory activity and for secretion in the absence of SycH. Coexpression of SycH and glutathione
S
-transferase (GST)-YscM1 or GST-YscM2, hybrid GST variants that cannot be transported by the type III apparatus, also relieved repression of Yop synthesis. GST-SycH bound to YscM1 and YscM2 and activated effector
yop
expression without initiation of the bound regulatory molecules into the type III pathway. Further, regulation of
yop
expression by YscM1, YscM2, and SycH is shown to act independently of factors that regulate secretion, and gel filtration chromotography revealed populations of YscM1 and YscM2 that are not bound to SycH under conditions where Yop synthesis is repressed. Taken together, these results suggest that YscM1- and YscM2-mediated repression may be relieved through binding to the cytoplasmic chaperone SycH prior to their type III injection into host cells.
Regulation ofl-Alanine Dehydrogenase inRhizobium leguminosarumbv.viciaeand Its Role in Pea Nodules
Authors: Lodwig Emma , Kumar Shalini , Allaway David , Bourdes Alex , Prell Jürgen , Priefer Ursula , Poole Philip
Published: January 2004

Alanine dehydrogenase (AldA) is the principal enzyme with which pea bacteroids synthesize alanine de novo. In free-living culture, AldA activity is induced by carboxylic acids (succinate, malate, and pyruvate), although the best inducer is alanine. Measurement of the intracellular concentration of alanine showed that AldA contributes to net alanine synthesis in laboratory cultures. Divergently transcribed fromaldAis an AsnC type regulator,aldR.Mutation ofaldRprevents induction of AldA activity. Plasmid-bornegusAfusions showed thataldRis required for transcription of bothaldAandaldR; hence, AldR is autoregulatory. However, plasmid fusions containing thealdA-aldRintergenic region could apparently titrate out AldR, sometimes resulting in a complete loss of AldA enzyme activity. Therefore, integratedaldR::gusAandaldA::gusAfusions, as well as Northern blotting, were used to confirm the induction ofaldAactivity. BothaldAandaldRwere expressed in the II/III interzone and zone III of pea nodules. Overexpression ofaldAin bacteroids did not alter the ability of pea plants to fix nitrogen, as measured by acetylene reduction, but caused a large reduction in the size and dry weight of plants. This suggests that overexpression ofaldAimpairs the ability of bacteroids to donate fixed nitrogen that the plant can productively assimilate. We propose that the role of AldA may be to balance the alanine level for optimal functioning of bacteroid metabolism rather than to synthesize alanine as the sole product of N2reduction.
The Left End of IS
2
: a Compromise between Transpositional Activity and an Essential Promoter Function That Regulates the Transposition Pathway
Authors: Lewis Leslie A. , Cylin Edruge , Lee Ho Kyung , Saby Robert , Wong Wilson , Grindley Nigel D. F.
Published: January 2004

Cut-and-paste (simple insertion) and replicative transposition pathways are the two classical paradigms by which transposable elements are mobilized. A novel variation of cut and paste, a two-step transposition cycle, has recently been proposed for insertion sequences of the IS
3
family. In IS
2
this variation involves the formation of a circular, putative transposition intermediate (the minicircle) in the first step. Two aspects of the minicircle may involve its proposed role in the second step (integration into the target). The first is the presence of a highly reactive junction formed by the two abutted ends of the element. The second is the assembly at the minicircle junction of a strong hybrid promoter which generates higher levels of transposase. In this report we show that IS
2
possesses a highly reactive minicircle junction at which a strong promoter is assembled and that the promoter is needed for the efficient completion of the pathway. We show that the sequence diversions which characterize the imperfect inverted repeats or ends of this element have evolved specifically to permit the formation and optimal function of this promoter. While these sequence diversions eliminate catalytic activity of the left end (IRL) in the linear element, sufficient sequence information essential for catalysis is retained by the IRL in the context of the minicircle junction. These data confirm that the minicircle is an essential intermediate in the two-step transposition pathway of IS
2
.
Transcriptional Profiling of Colicin-Induced Cell Death ofEscherichia coliMG1655 Identifies Potential Mechanisms by Which Bacteriocins Promote Bacterial Diversity
Authors: Walker Daniel , Rolfe Matthew , Thompson Arthur , Moore Geoffrey R. , James Richard , Hinton Jay C. D. , Kleanthous Colin
Published: January 2004

We report the transcriptional response ofEscherichia coliMG1655 to damage induced by colicins E3 and E9, bacteriocins that kill cells through inactivation of the ribosome and degradation of chromosomal DNA, respectively. Colicin E9 strongly induced the LexA-regulated SOS response, while colicin E3 elicited a broad response that included the induction of cold shock genes, symptomatic of translational arrest. Colicin E3 also increased the transcription of cryptic prophage genes and other laterally acquired mobile elements. The transcriptional responses to both these toxins suggest mechanisms that may promote genetic diversity inE. colipopulations, pointing to a more general role for colicins in adaptive bacterial physiology than has hitherto been realized.
DNA Binding by the Meningococcal RdgC Protein, Associated with Pilin Antigenic Variation
Authors: Moore Timothy , Sharples Gary J. , Lloyd Robert G.
Published: January 2004

The RdgC protein of
Neisseria gonorrhoeae
is required for efficient pilin antigenic variation, although its precise role has yet to be established. We demonstrate that the nearly identical RdgC from
Neisseria meningitidis
binds DNA with little specificity for sequence or structure, like the
Escherichia coli
protein. We also show that neither protein is able to constrain torsional tension in relaxed DNA. These data exclude several possible roles for RdgC in pilin antigenic variation and suggest that RdgC performs a similar function in both
E. coli
and the
Neisseria
spp.
Inhibiting Cell Division in
Escherichia coli
Has Little If Any Effect on Gene Expression
Authors: Arends S. J. Ryan , Weiss David S.
Published: January 2004

DNA microarrays were used to compare gene expression in dividing and nondividing (filamentous) cultures of
Escherichia coli
. Although cells from these cultures differed profoundly in morphology, their gene expression profiles were nearly identical. These results extend previous evidence that there is no division checkpoint in
E. coli
, and progression through the cell cycle is not regulated by the transcription of different genes during different parts of the cell cycle.
Expression of
Vibrio vulnificus
Capsular Polysaccharide Inhibits Biofilm Formation
Authors: Joseph Lavin A. , Wright Anita C.
Published: January 2004

Vibrio vulnificus
is a human pathogen that produces lethal septicemia in susceptible persons, and the primary virulence factor for this organism is capsular polysaccharide (CPS). The role of the capsule in
V. vulnificus
biofilms was examined under a variety of conditions, by using either defined CPS mutants or spontaneous CPS expression phase variants derived from multiple strains. CPS expression was shown to inhibit attachment and biofilm formation, which contrasted with other studies describing polysaccharides as integral to biofilms in related species.
Has2 is required upstream of Rac1 to govern dorsal migration of lateral cells during zebrafish gastrulation
Authors: Bakkers Jeroen , Kramer Carina , Pothof Joris , Quaedvlieg Nicolette E. M. , Spaink Herman P. , Hammerschmidt Matthias
Published: January 2004

The large extracellular polysaccharide Hyaluronan (HA) and its synthesizing enzymes (Has) have been implicated in regulating the migratory potential of metastatic cancer cells. Here, we analyze the roles of zebrafish Has2 in normal development. Antisense morpholino oligonucleotide (MO)-mediated knockdown of zebrafish Has2 leads to the loss of HA, and severe migratory defects during gastrulation, somite morphogenesis and primordial germ cell migration. During gastrulation, ventrolateral cells of has2 morphant embryos fail to develop lamellipodia and to migrate dorsally, resulting in a blockage of dorsal convergence, whereas extension of the dorsal axis is normal. The effect is cell autonomous, suggesting that HA acts as an autocrine signal to stimulate the migration of HA-generating cells. Upon ectopic expression in axial cells, has2 causes the formation of supernumerary lamellipodia and a blockage of axis extension. Epistasis analyses with constitutively active and dominant-negative versions of the small GTPase Rac1 suggest that HA acts by Rac1 activation, rather than as an essential structural component of the extracellular matrix. Together, our data provide evidence that convergence and extension are separate morphogenetic movements of gastrulation. In addition, they suggest that the same HA pathways are active to auto-stimulate cell migration during tumor invasion and vertebrate embryogenesis.
Drosophilaglypicans control the cell-to-cell movement of Hedgehog by a dynamin-independent process
Authors: Han Chun , Belenkaya Tatyana Y. , Wang Bei , Lin Xinhua
Published: January 2004

The signalling molecule Hedgehog (Hh) functions as a morphogen to pattern a field of cells in animal development. Previous studies in Drosophilahave demonstrated that Tout-velu (Ttv), a heparan sulphate polymerase, is required for Hh movement across receiving cells. However, the molecular mechanism of Ttv- mediated Hh movement is poorly defined. We show that Dally and Dally-like (Dly), two Drosophila glypican members of the heparan sulphate proteoglycan (HSPG) family, are the substrates of Ttv and are essential for Hh movement. We show that embryos lacking dly activity exhibit defects in Hh distribution and its subsequent signalling. However,both Dally and Dly are involved and are functionally redundant in Hh movement during wing development. We further demonstrate that Hh movement in its receiving cells is regulated by a cell-to-cell mechanism that is independent of dynamin-mediated endocytosis. We propose that glypicans transfer Hh along the cell membrane to pattern a field of cells.
SCL interacts with VEGF to suppress apoptosis at the onset of hematopoiesis
Authors: Martin Richard , Lahlil Rachid , Damert Annette , Miquerol Lucile , Nagy Andras , Keller Gordon , Hoang Trang
Published: January 2004

During development, hematopoiesis initiates in the yolk sac through a process that depends on VEGF/Flk1 signaling and on the function of the SCL/Tal1 transcription factor. Here we show that VEGF modifies the developmental potential of primitive erythroid progenitors and prolongs their life span. Furthermore, the survival of yolk sac erythrocytes in vivo depends on the dose of VEGF. Interestingly, in Vegflo/lo embryos carrying a hypomorph allele, Flk1-positive cells reach the yolk sac at E8.5,but are severely compromised in their ability to generate primitive erythroid precursors. These observations indicate that during embryonic development,different thresholds of VEGF are required for the migration and clonal expansion of hematopoietic precursors. The near absence of primitive erythroid precursors in Vegflo/lo embryos correlates with low levels of Scl in the yolk sac. Strikingly, gain-of-function of SCL partially complements the hematopoietic defect caused by the hypomorph Vegflo allele, and re-establishes the survival of erythroid cells and the expression of erythroid genes (Gata1 andβH1). This indicates that SCL functions downstream of VEGF to ensure an expansion of the hematopoietic compartment.
Missense mutations in the globular tail of myosin-Va indilutemice partially impair binding of Slac2-a/melanophilin
Authors: Fukuda Mitsunori , Kuroda Taruho S.
Published: January 2004

The well-known coat-color mutant mouse dilute exhibits a defect in melanosome transport, and although various mutations in the myosin-Va gene, which encodes an actin-based motor protein, have been identified in dilute mice, why missense mutations in the globular tail of myosin-Va, a putative cargo-binding site, cause the dilute phenotype (i.e. lighter coat color) has never been elucidated. In this study we discovered that missense mutations (I1510N, M1513K and D1519G) in the globular tail (GT) of myosin-Va partially impair the binding of Slac2-a/melanophilin, a linker protein between myosin-Va and Rab27A on the melanosome. The myosin-Va-GT-binding site in Slac2-a was mapped to the region (amino acids 147-240) adjacent to the N-terminal Rab27A-binding site, but it is distinct from the myosin-Va-exon-F-binding site (amino acids 320-406). The myosin-Va-GT·Slac2-a interaction was much weaker than the myosin-Va-exon-F·Slac2-a interaction. The missense mutations in the GT found in dilute mice abrogated only the myosin-Va-GT·Slac2-a interaction and had no effect on the myosin-Va-exon-F·Slac2-a interaction. We further showed that expression of green fluorescence protein-tagged Slac2-a lacking the myosin-Va-GT-binding site (ΔGT), but not the wild-type Slac2-a, severely inhibits melanosome transport in melan-a cells, especially at the melanosome transfer step from microtubles to actin filaments (i.e. perinuclear aggregation of melanosomes). On the basis of our findings, we propose that myosin-Va interacts with Slac2-a·Rab27A complex on the melanosome via two distinct domains, both of which are essential for melanosome transport in melanocytes.
Mevalonate kinase is a cytosolic enzyme in humans
Authors: Hogenboom Sietske , Tuyp John J. M. , Espeel Marc , Koster Janet , Wanders Ronald J. A. , Waterham Hans R.
Published: January 2004

In the past decade several reports have appeared which suggest that peroxisomes play a central role in isoprenoid/cholesterol biosynthesis. These suggestions were based primarily on the reported finding of several of the enzymes of the presqualene segment of the biosynthetic pathway in peroxisomes. More recently, however, conflicting results have been reported raising doubt about the postulated role of peroxisomes in isoprenoid biosynthesis, at least in humans. In this study we have studied the subcellular localisation of human mevalonate kinase (MK) using a variety of biochemical and microscopical techniques. These include conventional subcellular fractionation studies, digitonin permeabilisation studies, immunofluorescence microscopy and immunocytochemistry. We exclusively found a cytosolic localisation of both endogenous human MK (human fibroblasts, liver and HEK293 cells) and overexpressed human MK (human fibroblasts, HEK293 cells and CV1 cells). No indication of a peroxisomal localisation was obtained. Our results do not support a central role for peroxisomes in isoprenoid biosynthesis.
Planar polarity from flies to vertebrates
Authors: Fanto Manolis , McNeill Helen
Published: January 2004

Planar cell polarity (PCP) has been demonstrated in the epithelium of organisms from flies to humans. Recent research has revealed that the planar organization of cells requires a conserved set of genes, known as the PCP genes. Tbe PCP proteins Frizzled (Fz) and Dishevelled (Dsh) function as key players in PCP signalling. Although Fz and Dsh are also involved in Wingless (Wg)/Wnt signalling, these proteins have independent functions in a non-canonical pathway dedicated to PCP. Reorganization of the cell surface and cytoskeleton is required, and recent work has focused on how cell adhesion molecules (such as Fat, Dachsous and Flamingo) function in this process.
Definition of a spliceosome interaction domain in yeast Prp2 ATPase
Authors: EDWALDS-GILBERT GRETCHEN , KIM DONG-HO , SILVERMAN EDWARD , LIN REN-JANG
Published: January 2004

TheSaccharomyces cerevisiaesplicing factor Prp2 is an RNA-dependent ATPase required before the first transesterification reaction in pre-mRNA splicing. Prp2 binds to the spliceosome in the absence of ATP and is released following ATP hydrolysis. It contains three domains: a unique N-terminal domain, a helicase domain that is highly conserved in the DExD/H protein family, and a C-terminal domain that is conserved in spliceosomal DEAH proteins Prp2, Prp16, Prp22, and Prp43. We examined the role of each domain of Prp2 by deletion mutagenesis. Whereas deletions of either the helicase or C-terminal domain are lethal, deletions in the N-terminal domain have no detectable effect on Prp2 activity. Overexpression of the C-terminal domain of Prp2 exacerbates the temperature-sensitive phenotype of aprp2Tsstrain, suggesting that the C-domain interferes with the activity of the Prp2Tsprotein. A genetic approach was then taken to study interactions between Prp2 and the spliceosome. Previously, we isolated dominant negative mutants in the helicase domain of Prp2 that inhibit the activity of wild-type Prp2 when the mutant protein is overexpressed. We mutagenized oneprp2release mutant gene and screened for loss of dominant negative function. Several weak binding mutants were isolated and mapped to the C terminus of Prp2, further indicating the importance of the C terminus in spliceosome binding. This study is the first to indicate that amino acid substitutions outside the helicase domain can abolish spliceosome contact and splicing activity of a spliceosomal DEAH protein.
New directions for flashbulb memories: comments on the ACP Special Issue
Authors: Neisser Ulric
Published: January 2004

This commentary briefly addresses each of the ten papers in the special issue. The commentator's assessment is mixed: some of the papers seem to represent little or no advance, while others open up whole new areas of research. A number of concepts new to this area are introduced, including event memory (which was probably biased by extensive media coverage), expressive writing (which may have helped at least some participants deal with the stresses of 9/11), and the subjective probabilities of success and failure (which may have been temporarily shifted across whole populations). Copyright © 2003 John Wiley & Sons, Ltd.
Evidence for the differential impact of time and emotion on personal and event memories for September 11, 2001
Authors: Smith Marilyn C. , Bibi Uri , Sheard D. Erin
Published: January 2004

One week and six months following 9/11, University of Toronto students completed a questionnaire that assessed memory for that day's events. Questions assessed personal autobiographical information and event‐related information. Recently, Pezdek (2003) reported that ‘flash‐bulb memories’ for event and autobiographical information varied with the extent of participant involvement: as emotional involvement increased, event memory improved whereas autobiographical memory declined. This dichotomy was further explored in this study with a Canadian sample, a group expected to be less personally involved in the events. In accordance with Pezdek's hypothesis, the consistency of recall was better for autobiographical information than for event information. The two types of memories were also differentially affected by (1) emotion: event memory was better for those who experienced higher levels of emotion, whereas autobiographical memory was unaffected by emotion; and (2) the passage of time: over the six‐month interval, the accuracy of event memory declined, whereas the number of personal information details actually increased. Copyright © 2003 John Wiley & Sons, Ltd.
Delay related changes in personal memories for September 11, 2001
Authors: Lee Peter James , Brown Norman R.
Published: January 2004

This study examined delay related changes of people's recollections for 11th September 2001. 1481 participants were surveyed 4–24 hours or 10 days after the event. 142 participants were re‐tested in April, 2002. Test‐retest consistency was low after seven months (66.5%). Word counts for open ended descriptions revealed that people wrote significantly more contextual information 10 days after the event than respondents had on 11th or 12th September although no difference was found for retest participants 7 months later. Ratings for emotional reaction decreased monotonically over time. These results suggest early indexing may be a critical factor if the amount of information reported, type of information reported, or level of affect is a research issue. However, test‐retest consistency was not influenced by the ten day delay in indexing. Copyright © 2003 John Wiley & Sons, Ltd.
Comparing flashbulb memories of September 11 and the death of Princess Diana: effects of time delays and nationality
Authors: Kvavilashvili Lia , Mirani Jennifer , Schlagman Simone , Kornbrot Diana E.
Published: January 2004

This study examines flashbulb memories of a salient recent and a distant public event to assess patterns of forgetting in the formal characteristics of these memories. Memories of a recent event (September 11) were compared to memories of a distant event (the death of Princess Diana) in several samples of British and one sample of Italian participants. In British participants, the 51‐month old memories of the death of Princess Diana were as detailed and specific as their memories of a 3‐month old event, September 11. Moreover, their memories of Princess Diana were not different from memories of September 11 collected immediately or very soon after September 11 in two other groups of British participants. Results suggest that flashbulb memories of a distant public event can be as detailed, specific and vivid as memories of a very recent event. For Italian participants, however, flashbulb memory scores for September 11 were reliably higher than for the death of Princess Diana. There was also a small albeit reliable loss of specificity in British participants' memories of September 11 over the subsequent three months. Copyright © 2003 John Wiley & Sons, Ltd.
Event memory and autobiographical memory for the events of September 11, 2001
Authors: Pezdek Kathy
Published: January 2004

This research compares event memory and autobiographical memory for an event that was experienced to be more distressing, with more significant and widespread consequences than was any other event for which memory has been studied in a large sample. Memory for the events of September 11 was assessed seven weeks later in three samples: (a) 275 college students from Manhattan; (b) 167 college students from California; and (c) 127 college students from Hawaii. Whereas event memory was most accurate in the New York sample most involved in and most distressed by the events, autobiographical memory was reported with the least detail in this sample. This finding is consistent with the prediction that it is the synergy of arousal and rehearsal that affects memory for stressful events. Constructive memory distortions are also evident in the data; 73% of the respondents reported (incorrectly) that on September 11, they saw on television, the videotape of the first plane striking the first World Trade Center tower. Copyright © 2003 John Wiley & Sons, Ltd.
Autobiographical and event memory for 9/11: changes across one year
Authors: Tekcan Ali İ. , Ece Berivan , Gülgöz Sami , Er Nurhan
Published: January 2004

We tested Turkish participants' (n=483) autobiographical and event memory for the events of September 11, 2001 3 days, 6 months, and 1 year after the event. The amount of autobiographical detail participants reported was very high after one year. The accuracy of event memory was moderate at 3 days, and declined sharply by 6 months. The consistency of autobiographical memory was higher than that of event memory at all time lags; however, there was no interaction between time lag and memory type. The data also provided partial support for Pezdek's (2003) conceptualization that the degree of involvement has different effects on event and autobiographical memory. Copyright © 2003 John Wiley & Sons, Ltd.
Reconstructing the serial order of events: a case study of September 11, 2001
Authors: Altmann Erik M.
Published: January 2004

Participants reconstructed the serial order of events associated with the terrorist attacks of September 11, 2001. Accuracy was stable as the retention interval doubled from 9 weeks to 18 weeks, but most participants (63%) made errors sequencing even the ‘unforgettable’ events of that day, with most errors (72%) falling within one position of being correct. This positional gradient (near misses more common than far misses) mirrored that found in laboratory studies of order memory, despite basic differences in how ordinal information was presented to observers, suggesting that the positional gradient may generalize across many different circumstances of serial‐order reconstruction. Monte Carlo simulations illustrate this possibility by showing that simple constraints on pairs of events explain substantial variance in the data. Copyright © 2003 John Wiley & Sons, Ltd.
Reactions to and memories for the September 11, 2001 terrorist attacks in adults with posttraumatic stress disorder
Authors: Qin Jianjian , Mitchell Karen J. , Johnson Marcia K. , Krystal John H. , Southwick Steven M. , Rasmusson Ann M. , Allen Elizabeth S.
Published: January 2004

We examined emotional reactions to and subsequent memory for the September 11, 2001 terrorist attacks in individuals with a history of posttraumatic stress disorder (PTSD). Surveys were conducted among clients, staff, and visitors of a Veterans Administration Hospital approximately one month and again 10 months after the attacks. As compared to a trauma‐control group matched on age, sex, education, and veteran status, PTSD participants reported being more negatively affected by the attacks in the follow‐up, but not in the initial survey. PTSD and matched trauma control participants were similar in various measures of their initial autobiographical memory and event memory for factual details of the attacks. However, within‐subject comparison revealed significant forgetting over the 9 months in event memory only for the PTSD participants. Furthermore, PTSD participants exhibited a tendency to inflate the emotional aspects of their memory over time. Finally, only in the PTSD group, age was negatively correlated with event memory, suggesting an accelerated memory decline with age associated with PTSD. Copyright © 2003 John Wiley & Sons, Ltd.
Narratives of 9/11: relations among personal involvement, narrative content and memory of the emotional impact over time
Authors: Fivush Robyn , Edwards Valerie J. , Mennuti‐Washburn Jean
Published: January 2004

Previous research has documented the beneficial effects of expressive narrative writing, and especially the inclusion of cognitive processing and emotion words, for alleviating stress. In this study, 65 mostly white Emory University undergraduates of Judeo‐Christian backgrounds recalled their emotional reaction upon hearing the news of 9/11 within 2 months of the event, and again one month and 6 months later. Between the initial and one month assessment, participants engaged in expressive writing for 20 minutes a day for 5 consecutive days. Individuals who had higher personal involvement in the events of 9/11, through knowing someone who was killed or having lived in the affected areas, recalled being more shocked and upset upon hearing the news across time, and used fewer cognitive processing and positive emotion words in their narratives, than those with no direct involvement. Individuals who used more cognitive processing and emotion words in their narratives subsequently recalled being less shocked and upset upon hearing the news. Implications of these finding for emotional memory and emotional regulation are discussed. Copyright © 2003 John Wiley & Sons, Ltd.
How has the 9/11 terrorist attack influenced decision making?
Authors: Sacco Katiuscia , Galletto Valentina , Blanzieri Enrico
Published: January 2004

This paper investigates the effects of September 11, 2001 terrorists' attack on decision making. It was hypothesized that after terrorists' attacks people would make more conservative and less risky decisions, as a way of compensating for the feelings of insecurity caused by the disaster. Prospect Theory is used as theoretical framework. This theory has successfully accounted for decision making under normal circumstances. To verify whether and how the terrorists' attack against the USA influenced individual decision making processes, two samples of Italian university students were tested, one month and six months after the disaster. The results show the emergence of two tendencies, which are absent during ‘normal’ historical periods: a strong, long‐term lasting search for security when the outcome of a decision is perceived as a gain, and a medium‐term risk avoiding behavior in the loss domain. Copyright © 2003 John Wiley & Sons, Ltd.
Isaac, Ishmael, and Janus: past and future lessons regarding the ethnic categorization of faces
Authors: Rice Diana R. , Mullen Brian
Published: January 2004

The events of 9/11/2001 have stimulated an unprecedented degree of attention to, and efforts to identify, individuals of Arab descent. Following the Holocaust, social psychologists studied the extent to which Jewish and Non‐Jewish people could accurately categorize faces as Jewish vs. Non‐Jewish. This study provides a systematic analysis of the results of these earlier studies of the categorization of Jewish faces, with an eye toward informing the current cultural fixation upon the categorization of Arab faces. A meta‐analysis was conducted upon all available tests of the accuracy of categorization of Jewish and Non‐Jewish faces, allowing the empirical scrutiny of three models of facial perception. Judges can categorize Jewish faces to a significant, albeit extremely small degree; judges can categorize Non‐Jewish faces to a much greater degree. Results are most consistent with a model of facial perception that incorporates variations of cognitive representations of groups as a function of group size. These results suggest that training protocols for airport security guards should engage exemplar cognitive representations, emphasizing distinguishing features (rather than ethnic category membership) of faces. Copyright © 2003 John Wiley & Sons, Ltd.
Prader–Willi syndrome: Causes of death in an international series of 27 cases
Authors: Schrander‐Stumpel Constance Th.R.M. , Curfs Leopold M.G. , Sastrowijoto Prapto , Cassidy Suzanne B. , Schrander Jaap J.P. , Fryns Jean‐Pierre
Published: January 2004

Prader–Willi syndrome (PWS) is a complex condition with many medical and psychological features. In individuals with this syndrome, causes of death were studied. Data of 27 case reports were collected. Ages at death ranged from neonatal to 68 years. None of the individuals were treated with growth hormone (GH). Most cases were not completely documented and autopsy was performed in a minority of cases only. In five cases, death was considered not to be causally related to PWS. Hypotonia with hypoventilation was noted in the babies, and acute respiratory illness with unexpected sudden death was experienced in young children with PWS. Two young children died after a short period of fever and gastroenteritis. Obesity and its complications leading to death were pronounced in the adult group. One (possibly two) adult(s) died from gastric dilatation and shock. Based on these data, some cautious conclusions can be drawn. In babies with PWS hypoventilation is a risk factor; upper airway infection may be more serious than anticipated and any other clinical features pointing to an infection should be taken very seriously. Therefore, young infants with PWS hospitalized with an upper airway infection and/or hypoventilation or gastroenteritis symptoms, should be closely monitored. Early diagnosis and prevention of overweight is a major factor in preventing early causes of death in individuals with PWS. In the adult group, weight reduction is important but difficult to manage. Sleep apnea should be recognized and treated. Pain in the upper stomach and/or vomiting should be taken as a possible sign of acute intestinal dilatation; intravenous support may be life saving. © 2003 Wiley‐Liss, Inc.
Two cases of tetrasomy 9p syndrome with tissue limited mosaicism
Authors: Lloveras Elisabet , Pérez C. , Solé F. , Zamora L. , Lladonosa A. , Espinet B. , Silvestre E. , Serra J. , Vendrell T. , Fernández B. , Salido M. , Plaja A.
Published: January 2004

Tetrasomy of short arm of chromosome 9 constitutes a clinically recognizable chromosomal syndrome. Isochromosome 9p shows a strong propensity to tissue‐limited mosaicism. It occurs predominantly in peripheral blood cultures, often at a lower frequency or even absent in skin, amniotic fluid or chorionic villous cell cultures. Tissue‐limited nature of mosaicism may render prenatal detection of this condition very difficult. Herein, we report two new cases of mosaic tetrasomy 9p. Conventional cytogenetics (CC) and FISH studies demonstrated a differential expression of the mosaicism in several tissues. We review the literature and discuss the implications of these findings in cytogenetic prenatal diagnosis. © 2003 Wiley‐Liss, Inc.
Distinguishing Copper d8 and d10 Configurations in a Highly Ionic Complex; A Nonformal Metal Oxidation State
Authors: Snyder James P.
Published: January 2004

Copper(III) or copper(I)? The interpretation of the copper center in the anionic complex 1 as Cu1 by Snyder in the first issue of this year stimulated a spontaneous reply by Kaupp et al., which is published here with Snyder's response. The question whether the oxidation state in general is a purely formal concept has apparently not yet been answered to the satisfaction of all.
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Silicon Analogues of Grignard Compounds: Synthesis and Structure of Amine‐Stabilized Trimethylsilylmagnesium Halides
Authors: Goddard Richard , Krüger Carl , Ramadan Nazmi A. , Ritter Alfred
Published: January 2004

A SiMg bond replaces the CMg bond of standard Grignard reagents in the title compounds 1 and 2. They are synthesized from Me3SiHal and pyrophoric magnesium in the presence of complexing amine ligands. The crystal structures of 1 and 2 reveal that 1 exists in the solid state as an associated complex, whereas 2 is monomeric and has a pentacoordinate Mg atom.
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1,5‐Anhydrohexitol Nucleic Acids, a New Promising Antisense Construct
Authors: Aerschot Van Arthur , Verheggen Ilse , Hendrix Chris , Herdewijn Piet
Published: January 2004

For corrigendum see DOI:10.1002/anie.199521651
Synthesis of Hexagonally Packed Mesoporous TiO2 by a Modified Sol–Gel Method
Authors: Antonelli David M. , Ying Jackie Y.
Published: January 2004

Stable to surfactant removal by calcination, Ti‐TMS1 is the first hexagonally packed, mesoporous transition metal oxide. The synthesis of this new material was achieved by a modified sol–gel technique from titanium alkoxides and phosphate surfactants. The large internal surface area, narrow and controllable pore size, thermal stability, and variable oxidation states of the metal give this new material great potential as a catalyst and sorbent.
Aluminum(I) and Gallium(I) Compounds: Syntheses, Structures, and Reactions
Authors: Dohmeier Carsten , Loos Dagmar , Schnöckel Hansgeorg
Published: January 2004

By the end of the last century there were already the first indications of the possible existence of Al1 halides. However, it was only through the pioneering works of W. Klemm, who would have celebrated his 100th birthday on January 6, 1996, that detailed spectroscopic investigations became possible. Since the end of the 1970s the reactivity of AlX and GaX species in solid noble gases has been confirmed by numerous examples. In recent years formally monovalent Al and Ga species have been successfully synthesized on a preparative scale. In addition to the first halides, organometallic compounds with metal–metal bonds have been isolated and investigated with regard to their chemical properties. The fundamental importance of such species has been documented in this journal among others in the form of two highlight articles in which experimental and theoretical aspects have been examined with examples, and parallels and differences with respect to boron chemistry have been illustrated. This review is intended to give an account of the chronological development of this research area over the last few years, but an attempt is also made to categorize the experimental results achieved not only with respect to structure, thermodynamics, and reactivity, but also with the aid of quantum chemical calculations and by comparative considerations.
Nonstabilized Alkyl Complexes and Alkyl‐Cyano‐Ate Complexes of Iron(II) and Cobalt(II) as New Reagents in Organic Synthesis
Authors: Kauffmann Thomas
Published: January 2004

Alkyl transition metal reagents are being increasingly used for alkylations in organic synthesis. They have various advantages over alkyllithium and alkyl‐magnesium reagents including higher selectivity, lower basicity, and—as long as the transition metal is not in its highest oxidation state—their willingness to undergo oxidative addition with electrophiles. Alkyl derivatives of FeII and CoII, which are not stabilized by special ligands but still can be easily handled, are in many cases superior to the well‐known alkyl–CuI and ‐MnII reagents and can also undergo unexpected reactions. The introduction of alkyl‐cyanoate complexes of FeII and CoII, the cyanide ligands of which (in contrast to neutral π‐acidic ligands) do not reduce the reactivity, has led to further advances. Reaction mechanisms will be discussed and comparisons will be made with alkylating reagents containing CuI, MnII, NiII, or TiIV as well as with Pd‐catalyzed coupling reactions. Furthermore, it will be shown that super‐ate FeII complexes are almost certainly the reactive species in highly selective catalytic alkylations.
Self‐Assembly in Natural and Unnatural Systems
Authors: Philp Douglas , Stoddart J. Fraser
Published: January 2004

Although there are no fundamental factors hindering the development of nanoscale structures, there is a growing realization that “engineering down” approaches, in other words a reduction in the size of structures generated by lithographic techniques below the present lower limit of roughly 1 μm, may become impractical. It has, therefore, become increasingly clear that only by the development of a fundamental understanding of the self‐assembly of large‐scale biological structures, which exist and function at and beyond the nanoscale, downwards, and the extension of our knowledge regarding the chemical syntheses of small‐scale structures upwards, can the gap between the promise and the reality of nanosystems be closed. This kind of construction of nanoscale structures and nanosystems represents the so‐called “bottom up” or “engineering up” approach to device fabrication. Significant progress can be made in the development of nanoscience by transferring concepts found in the biological world into the chemical arena. Central to this mission is the development of simple chemical systems capable of instructing their own organization into large aggregates of molecules through their mutual recognition properties. The precise programming of these recognition events, and hence the correct assembly of the growing superstructure, relies on a fundamental understanding and the practical exploitation of non‐covalent bonding interactions between and within molecules. The science of supramolecular chemistry—chemistry beyond the molecule in its very broadest sense—has started to bridge the yawning gap between molecular and macro‐molecular structures. By utilizing inter‐actions as diverse as aromatic π–π stacking and metal–ligand coordination for the information source for assembly processes, chemists have, in the last decade, begun to use biological concepts such as self‐assembly to construct nanoscale structures and superstructures with a variety of forms and functions. Here, we provide a flavor of how self‐assembly operates in natural systems and can be harnessed in unnatural ones.
Synthesis of New Dialkylmagnesium Compounds by Living Transfer Ethylene Oligo‐ and Polymerization with Lanthanocene Catalysts
Authors: Pelletier Jean‐François , Mortreux André , Olonde Xavier , Bujadoux Karel
Published: January 2004

Useful intermediates for the synthesis of functionalized, linear alkyl chains by classical Grignard reactions or reactants for the synthesis of biblock copolymers by further reaction with polar monomers—the dialkylmagnesium compounds described herein are accessible in a living transfer polymerization under very mild conditions with [CpLnCl2Li(OEt2)2] (Ln = Nd, Sm) as catalysts and simple dialkylmagnesium compounds RMgR′ (R = Et, R′ = Bu or R = R′ = n‐hexyl) using ethylene as substrate.
What Can We Learn from Molecular Recognition in Protein–Ligand Complexes for the Design of New Drugs?
Authors: Böhm Hans‐Joachim , Klebe Gerhard
Published: January 2004

The understanding of noncovalent interactions in protein–ligand complexes is essential in modern biochemistry and should contribute toward the discovery of new drugs. In the present review, we summarize recent work aimed at a better understanding of the physical nature of molecular recognition in protein–ligand complexes and also at the development and application of new computational tools that exploit our current knowledge on structural and energetic aspects of protein–ligand interactions in the design of novel ligands. These approaches are based on the exponentially growing amount of information about the geometry of protein structures and the properties of small organic molecules exposed to a structured molecular environment. The various contributions that determine the binding affinity of ligands toward a particular receptor are discussed. Their putative binding site conformations are analyzed, and some predictions are attempted. The similarity of ligands is examined with respect to their recognition properties. This information is used to understand and propose binding modes. In addition, an overview of the existing methods for the design and selection of novel protein ligands is given.
Carbenoid Complexes of Electron‐Deficient Transition Metals—Syntheses of and with Short‐Lived Building Blocks
Authors: Beckhaus Rüdiger
Published: January 2004

The relation of thermodynamic stability and kinetic lability of σ‐organometallic compounds of transition metals, together with an improved understanding of the subtle interactions between central metal, ligands, and substrates, has increased the chemist's ability to plan organometallic syntheses. This article presents new results on intermediary and isolable synthetic building blocks incorporating metal–ligand multiple bonds of electron‐deficient transition metals; the main emphasis will be placed on compounds with titanium–carbon double bonds. This particular class of compounds is mainly generated by H‐transfer reactions starting from readily accessible alkyl and alkenyl derivatives. The preparative use of [L2Ti(CHR2)R′] derivatives as sources for [L2TiCR2] intermediates will be discussed, as well as the nature of these intermediates. Application of the same approach to vinyltitanium compounds [L2Ti(CHCH2)R] opens up an access to a short‐lived metallaallene derivative [L2TiCCH2] of an electron‐deficient transition metal. The reactivity of these synthetic building blocks is mainly characterized by the nucleophilic properties of the α‐C atoms as well as by the spatial orientation of the π‐bonding planes. Numerous cycloaddition products with unsaturated substrates could be isolated and characterized for the first time by using [L2TiCCH2] intermediates. Hence it is possible to compare the properties of a multitude of metallacyclic ring systems with those obtained from “Tebbe–Grubbs chemistry”, and in this context, the dependence of the properties of metallacyclic four‐membered rings on the substitution pattern is discussed. This class of compounds includes the metallaoxetanes, which have been obtained for the first time by the cycloaddition of the [CpTiCCH2] intermediate with cumulenes and metal carbonyls. The differing cycloreversion behavior of these metallaoxetanes enables the differentiation of species exhibiting classical and nonclassical reactivity. The number and position of the exocyclic double bonds are the determining factors of the reactivity of the formed metallacycles. The discussion of the products obtained from titanium methylene and vinylidene building blocks is an up‐to‐date report on the formation and applications of carbene complexes and carbene intermediates of group 4 metals.