bluuebunny/crossref_metadata_2025_split huggingface dataset:
CesT is a multi‐effector chaperone and recruitment factor required for the efficient type III secretion of both LEE‐ and non‐LEE‐encoded effectors of enteropathogenic Escherichia coli
Authors: Thomas Nikhil A. , Deng Wanyin , Puente Jose L. , Frey Elizabeth A. , Yip Calvin K. , Strynadka Natalie C. J. , Finlay B. Brett 
Published: August 2005

SummaryEnteropathogenic Escherichia coli (EPEC) is an intestinal attaching and effacing pathogen that utilizes a type III secretion system (T3SS) for the delivery of effectors into host cells. The chaperone CesT has been shown to bind and stabilize the type III translocated effectors Tir and Map in the bacterial cytoplasm prior to their delivery into host cells. In this study we demonstrate  a  role  for  CesT  in  effector  recruitment  to the membrane embedded T3SS. CesT‐mediated effector recruitment was dependent on the presence of the T3SS membrane‐associated ATPase EscN. EPEC ΔcesT carrying a C‐terminal CesT variant, CesT(E142G), exhibited normal cytoplasmic Tir stability function, but was less efficient in secreting Tir, further implicating CesT in type III secretion. In vivo co‐immunoprecipitation studies using CesT‐FLAG containing EPEC lysates demonstrated that CesT interacts with Tir and EscN, consistent with the notion of CesT recruiting Tir to the T3SS. CesT was also shown to be required for the efficient secretion of several type III effectors encoded within and outside the locus of enterocyte effacement (LEE) in addition to Tir and Map. Furthermore, a CesT affinity column was shown to specifically retain multiple effector proteins from EPEC culture supernatants. These findings indicate that CesT is centrally involved in recruiting multiple type III effectors to the T3SS via EscN for efficient secretion, and functionally redefine the role of CesT in multiple type III effector interactions.
The fungal hydrophobin RolA recruits polyesterase and laterally moves on hydrophobic surfaces
Authors: Takahashi Toru , Maeda Hiroshi , Yoneda Sachiyo , Ohtaki Shinsaku , Yamagata Yohei , Hasegawa Fumihiko , Gomi Katsuya , Nakajima Tasuku , Abe Keietsu 
Published: August 2005

SummaryWhen fungi grow on plant or insect surfaces coated with wax polyesters that protect against pathogens, the fungi generally form aerial hyphae to contact the surfaces. Aerial structures such as hyphae and conidiophores are coated with hydrophobins, which are surface‐active proteins involved in adhesion to hydrophobic surfaces. When the industrial fungus Aspergillus oryzae was cultivated in a liquid medium containing the biodegradable polyester polybutylene succinate‐coadipate (PBSA), the rolA gene encoding hydrophobin RolA was highly transcribed. High levels of RolA and its localization on the cell surface in the presence of PBSA were confirmed by immunostaining. Under these conditions, A. oryzae simultaneously produced the cutinase CutL1, which hydrolyses PBSA. Pre‐incubation of PBSA with RolA stimulated PBSA degradation by CutL1, suggesting that RolA bound to the PBSA surface was required for the stimulation. Immunostaining revealed that PBSA films coated with RolA specifically adsorbed CutL1. Quartz crystal microbalance analyses further demonstrated that RolA attached to a hydrophobic sensor chip specifically adsorbed CutL1. Circular dichroism spectra of soluble‐state RolA and bound RolA suggested that RolA underwent a conformational change after its adsorption to hydrophobic surfaces. These results suggest that RolA adsorbed to the hydrophobic surface of PBSA recruits CutL1, resulting in condensation of CutL1 on the PBSA surface and consequent stimulation of PBSA hydrolysis. A fluorescence recovery after photobleaching experiment on PBSA films coated with FITC‐labelled RolA suggested that RolA moves laterally on the film. We discuss the novel molecular functions of RolA with regard to plastic degradation.
TrmB, a sugar sensing regulator of ABC transporter genes in Pyrococcus furiosus exhibits dual promoter specificity and is controlled by different inducers
Authors: Lee Sung‐Jae , Moulakakis Christina , Koning Sonja M. , Hausner Winfried , Thomm Michael , Boos Winfried 
Published: August 2005

SummaryTrmB is the transcriptional repressor for the gene cluster of the trehalose/maltose ABC transporter of the hyperthermophilic archaea Thermococcus litoralis and Pyrococcus furiosus (malE or TM operon), with maltose and trehalose acting as inducers. We found that TrmB (the protein is identical in both organisms) also regulated the transcription of genes encoding a separate maltodextrin ABC transporter in P. furiosus (mdxE or MD operon) with maltotriose, longer maltodextrins and sucrose acting as inducers, but not with maltose or trehalose. In vitro transcription of the malE and the mdxE operons was inhibited by TrmB binding to the different operator sequences. Inhibition of the TM operon was released by maltose and trehalose whereas inhibition of the MD operon was released by maltotriose and larger maltodextrins as well as by sucrose. Scanning mutagenesis of the TM operator revealed the role of the palindromic TACTNNNAGTA sequence for TrmB recognition. TrmB exhibits a broad spectrum of sugar‐binding specificity, binding maltose, sucrose, maltotriose and trehalose in decreasing order of affinity, half‐maximal binding occurring at 20, 60, 250 and 500 µM substrate concentration respectively. Of all substrates, only maltose shows sigmoidal binding characteristics with a Hill coefficient of 2. As measured by molecular sieve chromatography and cross‐linking TrmB behaved as dimer in dilute buffer solution at room temperature. We conclude that TrmB acts as a bifunctional transcriptional regulator acting on two different promoters and being differentially controlled by binding to different sugars. We believe this to represent a novel strategy of prokaryotic transcription regulation.
Transcriptional autoregulation by quorum sensing Escherichia coli regulators B and C (QseBC) in enterohaemorrhagic E. coli (EHEC)
Authors: Clarke Marcie B. , Sperandio Vanessa 
Published: August 2005

SummaryThe cell‐to‐cell communication system referred to as quorum sensing (QS) is based on the principle that bacteria secrete hormone‐like compounds referred to as autoinducers. Upon reaching a threshold concentration, these autoinducers interact with transcription factors to regulate gene expression. We previously reported that enterohaemorrhagic Escherichia coli (EHEC), which is responsible for outbreaks of bloody diarrhoea, utilizes a QS system to regulate gene transcription. We have also previously shown that the quorum sensing E. coli regulators B and C (QseBC) may act as a two‐component system to transcriptionally regulate the expression of flagella and motility. Here, using a reverse transcription polymerase chain reaction (RT‐PCR), we show that qseBC are transcribed in an operon. Furthermore, using a qseBC::lacZ transcriptional fusion, we observed that QseB autoactivates its own transcription. In addition, the transcriptional start site of the qseBC promoter responsive to QseBC was mapped, and single‐copy and multicopy deletion analyses were performed to determine the minimal region necessary for QseB transcriptional activation. These data allowed us to map an additional transcriptional start site for the qseBC promoter which may allow for a basal level of QseBC expression. Finally, electrophoretic mobility shift assays, competition experiments and DNase I footprints were performed and demonstrated that QseB directly binds to two sites in its own promoter. These results indicate that QseB may act to autoregulate its own transcription through binding to low‐ and high‐affinity sites found in its promoter.
Priming of the immune response by schistosome eggs
Authors: PEARCE E. J. 
Published: August 2005

SUMMARY Schistosomiasis mansoni is a chronic disease caused by infection with helminths of the genus Schistosoma mansoni. Adult schistosomes live intravascularly, and for transmission of this infection it is necessary for parasite eggs to traverse the endothelium, and migrate to the intestinal lumen, from where they can exit the body to continue the lifecycle. This process is dependent on an intact host CD4 T helper (Th) cell response to egg antigens. Perhaps because of this, eggs have evolved to be highly immunogenic and capable of inducing potent Th responses. The egg‐induced Th response is unusual in that it is highly Th2‐polarized. The selective pressure on the host to mount a Th2 response against eggs is apparent in the fact that Th2 response‐defective mice develop acutely lethal disease when infected with schistosomes. In this review I will focus on the underlying basis for the Th2 bias in the immune response to egg antigens.
Immunity to schistosomiasis in animals: an update
Authors: VERCRUYSSE J. , GABRIEL S. 
Published: August 2005

SUMMARY The present paper reviews the available literature on the development of immunity to animal Schistosoma infections. The majority of the studies on animal schistosomiasis were performed in cattle and pigs and only Schistosoma mattheei, S. bovis and S. japonicum received particular attention, mainly because of their recognized veterinary significance or zoonotic aspect. Although it is an accepted fact that acquired resistance to Schistosoma is of major importance in the regulation of infection intensity in the field, almost nothing is yet known of either the nature of the antigens or of the immune mechanisms involved. The recent studies on immunity development focus in particular on the occurrence of maternal to foetal transfer of immunological substances related to animal Schistosoma infections and possible effects of these transfers on the immunity development of the foetus/newborn. Since congenital infections for Schistosoma species other than S. japonicum are extremely rare, the most plausible route for foetal contact is the transplacental or postnatal transfer of immunological substances. Prenatal transfers of specific antibodies and antigens via placental lesions and postnatal transfers via the colostrum were observed in cattle and pigs, and subsequent modifications of the immune response of the newborn were observed. Placental lesions induced by Schistosoma eggs could allow other pathogens to cross the placenta.
Schistosome glycans and innate immunity
Authors: HOKKE C. H. , YAZDANBAKHSH M. 
Published: August 2005

SUMMARY Schistosome glycans induce characteristic innate immune responses in the infected host. The molecular aspects of these responses, the pathways and receptors as well as the schistosome glycans and glycoconjugates involved, form an area of intense research. The relevant schistosome glycan elements and the possible mechanisms through which they act on the innate immune system are discussed in this review.
Resistance to re‐infection after exposure to normal and attenuated schistosome parasites in the baboon model
Authors: KARIUKI T. M. , FARAH I. O. 
Published: August 2005

SUMMARY The baboon model of schistosomiasis has been used extensively to study parasite biology, immune responses and pathological manifestations after natural and experimental infections. The body of knowledge accumulated so far has placed this animal model at the pinnacle in the continuing search for new interventions and might hold the key to the development of new anti‐schistosome vaccines. In this review paper, we highlight previous and recent studies that have elevated the baboon to be the model of choice for schistosomiasis research. In particular, the long‐term studies of re‐infection after chemotherapy as well as the interaction between vaccination, chemotherapy and infection are highlighted.
Origins, genetic organization and transcription of a family of non‐autonomous helitron elements in maize
Authors: Brunner Stephan , Pea Giorgio , Rafalski Antoni 
Published: September 2005

SummaryHelitron transposable elements carrying gene fragments were recently discovered in maize. These elements are frequently specific to certain maize lineages. Here we report evidence supporting the involvement of helitrons in the rapid evolution of the maize genome, in particular in the multiplication of related genic fragments across the genome. We describe a family of four closely related, non‐autonomous maize helitrons and their insertion sites at four non‐allelic genetic loci across the maize genome: two specific to the B73 inbred, and two to the Mo17 inbred. We propose the phylogeny of this helitron family and provide an approximate timeline of their genomic insertions. One of these elements, the Mo17‐specific helitron on chromosome 1 (bin 1.07), is transcriptionally active, probably as a result of insertion in the vicinity of a promoter. Significantly, it produces an alternatively spliced and chimeric transcript joining together genic segments of different chromosomal origin contained within the helitron. This transcript potentially encodes up to four open reading frames. During the course of evolution, transcribed helitrons containing multiple gene fragments may occasionally give rise to new genes with novel biochemical functions by a combinatorial assembly of exons. Thus helitrons not only constantly reshape the genomic organization of maize and profoundly affect its genetic diversity, but also may be involved in the evolution of gene function.
Arabidopsis RecQl4A suppresses homologous recombination and modulates DNA damage responses
Authors: Bagherieh‐Najjar Mohammad B. , de Vries Onno M.H. , Hille Jacques , Dijkwel Paul P. 
Published: September 2005

SummaryThe DNA damage response and DNA recombination are two interrelated mechanisms involved in maintaining the integrity of the genome, but in plants they are poorly understood. RecQ is a family of genes with conserved roles in the regulation of DNA recombination in eukaryotes; there are seven members in Arabidopsis. Here we report on the functional analysis of the Arabidopsis RecQl4A gene. Ectopic expression of Arabidopsis RecQl4A in yeast RecQ‐deficient cells suppressed their hypersensitivity to the DNA‐damaging drug methyl methanesulfonate (MMS) and enhanced their rate of homologous recombination (HR). Analysis of three recQl4A mutant alleles revealed no obvious developmental defects or telomere deregulation in plants grown under standard growth conditions. Compared with wild‐type Arabidopsis, the recQl4A mutant seedlings were found to be hypersensitive to UV light and MMS, and more resistant to mitomycin C. The average frequency of intrachromosomal HR in recQl4A mutant plants was increased 7.5‐fold over that observed in wild‐type plants. The data reveal roles for Arabidopsis RecQl4A in maintenance of genome stability by modulation of the DNA damage response and suppression of HR.
Arabidopsis peroxisomes possess functionally redundant membrane and matrix isoforms of monodehydroascorbate reductase
Authors: Lisenbee Cayle S. , Lingard Matthew J. , Trelease Richard N. 
Published: September 2005

SummaryThe H2O2 byproduct of fatty acid catabolism in plant peroxisomes is removed in part by a membrane‐associated antioxidant system that involves both an ascorbate peroxidase and a monodehydroascorbate reductase (MDAR). Despite descriptions of 32‐kDa MDAR polypeptides in pea and castor peroxisomal membranes and cDNA sequences for several ‘cytosolic’ MDARs, the genetic and protein factors responsible for peroxisomal MDAR function have yet to be elucidated. Of the six MDAR polypeptides in the Arabidopsis proteome, named AtMDAR1 to AtMDAR6 in this study, 47‐kDa AtMDAR1 and 54‐kDa AtMDAR4 possess amino acid sequences that resemble matrix (PTS1) and membrane peroxisomal targeting signals, respectively. Epitope‐tagged versions of these two MDARs and a pea 47‐kDa MDAR (PsMDAR) sorted in vivo directly from the cytosol to peroxisomes in Arabidopsis and BY‐2 suspension cells, whereas AtMDAR2 and AtMDAR3 accumulated in the cytosol. The PTS1‐dependent sorting of AtMDAR1 and PsMDAR to peroxisomes was incomplete (inefficient?), but was improved for PsMDAR after changing its PTS1 sequence from –SKI to the canonical tripeptide –SKL. A C‐terminal transmembrane domain and basic cluster of AtMDAR4 were necessary and sufficient for targeting directly to peroxisomes. MDAR activity in isolated Arabidopsis peroxisomes was distributed among both water‐soluble matrix and KCl‐insoluble membrane subfractions that contained respectively 47‐ and 54‐kDa MDAR polypeptides. Notably, a 32‐kDa MDAR was not identified. Combined with membrane association and topological orientation findings, these results indicate that ascorbate recycling in Arabidopsis (and probably other plant) peroxisomes is coordinated through functionally redundant MDARs that reside in the membrane and the matrix of the organelle.
A community‐based study to examine the effect of a youth HIV prevention intervention on young people aged 15–24 in South Africa: results of the baseline survey
Authors: Pettifor Audrey E. , Kleinschmidt Immo , Levin Jonathan , Rees Helen V. , MacPhail Catherine , Madikizela‐Hlongwa Lindiwe , Vermaak Kerry , Napier Grant , Stevens Wendy , Padian Nancy S. 
Published: August 2005

SummaryObjectives  To determine whether South African youths living in communities that had either of two youth human immunodeficiency virus (HIV) prevention interventions [(a) loveLife Youth Centre or (b) loveLife National Adolescent Friendly Clinic Initiative] would have a lower prevalence of HIV, sexually transmitted infections (STIs), and high risk sexual behaviours than communities without either of these interventions.Methods  In 2002 the baseline survey of a quasi‐experimental, community‐based study was conducted in South Africa. In total 33 communities were included in three study arms (11 communities per study arm). The final sample included 8735 youths aged 15–24 years. All participants took part in a behavioural interview and were tested for HIV, gonorrhoea (Neisseria gonorrhoeae) and Chlamydia (Chlamydia trachomatis).Results  HIV prevalence was 20.0% among females and 7.5% among males (OR 3.93 95% CI 2.51–6.15). There were no significant differences between study arms for HIV, NG or CT prevalence at baseline. In multiple regression analyses, HIV was significantly associated with NG infection (OR 1.96 95% CI 1.24–3.12) but not with CT infection. Youths who reported >1 lifetime partner were also significantly more likely to be infected with HIV (OR 1.98 95% CI 1.55–2.52), as were those who reported ever having engaged in transactional sex (OR 1.86 P = 0.02) or having had genital ulcers in the past 12 months (OR 1.71 P ≤ 0.001).Conclusions  HIV prevention programmes must ensure that gender inequities that place young women at greater risk for HIV infection are urgently addressed and they must continue to emphasize the importance of reducing the number of sexual partners and STI treatment.
Birth month and sensitization to house dust mites in asthmatic children
Authors: Yoo Y. , Yu J. , Kang H. , Kim D. K. , Koh Y. Y. , Kim C. K. 
Published: August 2005

Background:  Early exposure to high quantities of allergen has an important role in the incidence of atopic sensitization. In fact, subjects sensitized to house dust mites (HDMs) have a significantly higher proportion of births in the season when HDMs are most abundant.Objective:  The aim of this study was to investigate whether birth month patterns differ for asthmatic patients sensitized only to HDMs and for those sensitized to HDMs and other allergen(s).Methods:  Among 2225 patients with asthma, aged 10–16 years, 1642 sensitized to HDMs were identified by skin prick testing. This group was composed of patients sensitized only to HDMs (n = 715) and patients sensitized to HDMs and other allergen(s) (n = 927). The birth month distributions of the group of HDM‐sensitive asthmatics or its subgroups were compared with that of a reference population (total live births in the same years as the studied subjects). The risk ratio of a given birth month in relation to all the other months was calculated as an odds ratio (OR) with the corresponding 95% confidence interval (CI).Results:  A significant difference in birth month distribution was observed for HDM‐sensitive asthmatics (χ2 = 23.6, P = 0.015), with higher rates of birth in August (OR: 1.23, 95% CI: 1.04–1.46) and September (1.24, 1.04–1.46). When the two subgroups were analyzed separately, significantly more births were noted in August (1.34, 1.06–1.71) and September (1.34, 1.05–1.70) for those sensitized only to HDMs, whereas no such birth month preference was observed for those sensitized to HDMs and other allergen(s).Conclusions:  The HDM‐positive asthmatics showed a greater proportion of births in August and September, which correspond to high HDM exposure. However, this birth month pattern was evident in asthmatic‐sensitive only to HDMs, but was not observed in those sensitive to HDMs and other allergen(s).
Detection of differentiation‐ and activation‐linked cell surface antigens on cultured mast cell progenitors
Authors: Schernthaner G.‐H. , Hauswirth A. W. , Baghestanian M. , Agis H. , Ghannadan M. , Worda C. , Krauth M.‐T. , Printz D. , Fritsch G. , Sperr W. R. , Valent P. 
Published: August 2005

Background:  Mast cells (MC) are multifunctional effector cells of the immune system. They derive from uncommitted CD34+ hemopoietic progenitor cells (HPC). Depending on the stage of maturation and the environment, MC variably express differentiation‐ and activation‐linked antigens. Little is known, however, about the regulation of expression of such antigens in immature human MC.Methods:  We analyzed expression of CD antigens on human MC grown from cord blood‐derived CD34+ HPC. The HPC were isolated by magnetic cell sorting (MACS) and FACS to >97% purity, and were cultured in stem cell factor (SCF) and interleukin (IL)‐6 with or without additional cytokines (IL‐4 or IL‐10) in serum‐free medium. The cell surface phenotype of MC was determined by monoclonal antibodies and flow cytometry.Results:  Cultured MC progenitors were found to react with antibodies against various CD antigens including CD58, CD63, CD117, CD147, CD151, CD203c, and CD172a, independent of the growth factors used and time‐point investigated (days 14–42). CD116 [granulocyte–macrophage colony‐stimulating factor receptor α (GM‐CSFRα)] and CD123 (IL‐3Rα) were expressed on MC precursors on day 14, but disappeared thereafter. Cultured MC did not express CD2, CD3, CD5, CD10, CD19, or CD25. Addition of IL‐10 to MC cultures showed no effect on expression of CD antigens. However, IL‐4 was found to promote expression of CD35 and CD88 on cultured MC without changing expression of other CD antigens.Conclusions:  Most MC antigens may already be expressed at an early stage of mastopoiesis. Whereas IL‐3R and GM‐CSFRs are lost during differentiation of MC, these cells may acquire complement receptors (CD35, CD88) under the influence of distinct cytokines.