bluuebunny/crossref_metadata_2025_split huggingface dataset:
Apolipoprotein E3Basel: new insights into a highly conserved protein region
Authors: Miserez A. R. , Scharnagl H. , Muller P. Y. , Mirsaidi R. , Stähelin H. B. , Monsch A. , März W. , Hoffmann M. M. 
Published: July 2003

AbstractBackground Apolipoprotein E is important for the receptor‐mediated uptake of triglyceride‐rich lipoproteins. Mutations in the gene encoding apolipoprotein E may cause a reduced uptake of these lipoproteins. Particular apolipoprotein E mutations have been also found to be associated with nephrologic, neurologic, and even ophthalmologic diseases. Hence, a continuously expanding role in biology is being attributed to this protein.Design Randomly selected volunteers from of a large Swiss cohort were genotyped for the common apolipoprotein E isoforms (apolipoprotein E2, apolipoprotein E3, apolipoprotein E4).Results In one of the volunteers, a novel C‐to‐T mutation causing an alanine‐to‐valine substitution (A106V, designated apolipoprotein E3Basel) was discovered. Alanine at residue 106 is highly conserved between mammalian species and is located in the immediate vicinity of the 112C/R polymorphism (apolipoprotein E4). Recombinant apolipoprotein E3Basel, expressed in the baculovirus system, displayed no detectable reduction in its low density lipoprotein (LDL) receptor‐ and heparin‐binding activities. Despite normal binding functions, apolipoprotein E3Basel might cause modifications in the lipoprotein pattern. In the index case, plasma triglycerides were elevated and in two further apolipoprotein E3Basel‐carriers, cholesterol, phospholipid, apolipoprotein CIII levels, LDL‐cholesterol/apoB‐100‐ and VLDL‐triglyceride/VLDL‐cholesterol‐ratios were higher compared with apolipoprotein E3Basel‐noncarriers when pair‐matched for age and gender. One of the four apolipoprotein E3Basel‐carriers from the index family had a personal history of Alzheimer's disease.Conclusions Alanine at amino acid position 106 is highly conserved but not crucial in the receptor‐mediated uptake of lipoprotein particles. Nevertheless, amino acid position 106 might be involved in the apolipoprotein E‐dependent regulation of the lipoprotein lipase that hydrolyzes triglycerides and in the development of Alzheimer's disease.
Acute‐phase response of human hepatocytes after infection with Chlamydia pneumoniae and cytomegalovirus
Authors: Verkerk M. S. A. , Visseren F. L. J. , Paul Bouter K. , Diepersloot R. J. A. 
Published: July 2003

AbstractBackground There is increasing evidence that chronic inflammation plays a pivotal role in the development of atherosclerosis. Whether inflammation is the cause or consequence of vascular damage is unclear. Also, the source of inflammation is unknown, but may well be infection by Cytomegalovirus (CMV) or Chlamydia pneumoniae (C. pneumoniae). Infection of the liver by CMV or C. pneumoniae may induce a general inflammatory reaction contributing to accelerated atherogenesis.In this study we investigated the production of interleukin‐6 (IL‐6), fibrinogen and plasminogen activator inhibitor‐1 (PAI‐1) by hepatocytes after infection with CMV or C. pneumoniae.Methods HepG2 cell monolayers were grown to confluence in 48‐well tissue culture plates. Hepatocytes were infected with 50 µL or 100 µL of suspension of CMV (102·70 TCID50 mL−1) and C. pneumoniae (104·75 TCID50 mL−1). The medium of the inoculated cells was collected every 24 h, from day 1 to day 4, for determination of IL‐6, PAI‐1 and fibrinogen concentrations.Results Fibrinogen production was increased significantly in a dose‐dependent manner after infection with CMV (50 µL: P = 0·022 and 100 µL: P < 0·001) and C. pneumoniae (P = 0·012). Cytomegalovirus infection resulted in an increase of IL‐6 production compared with uninfected cells (P = 0·048). Cytomegalovirus and C. pneumoniae infection did not result in a significantly increase of PAI‐1 production by hepatocytes.Conclusion We conclude that in addition to direct vascular wall infection by C. pneumoniae and CMV, virus‐related development of atherosclerosis might also be initiated by chronic liver infection and subsequent production of inflammatory and procoagulant mediators released in the circulation. This may be another pathophysiological link for the observed relation between infections and the development of atherosclerosis.
Relation between insulin kinetics and insulin sensitivity in pregnancy
Authors: Jolly M. C. , Hovorka R. , Godsland I. , Amin R. , Lawrence N. , Anyaoku V. , Johnston D. , Robinson S. 
Published: July 2003

AbstractBackground Different time‐concentration profiles of plasma insulin following insulin modification of a frequently sampled intravenous glucose‐tolerance‐test (FSIVGTT) were observed in a study investigating maternal metabolism and fetal macrosomia. We aimed to investigate whether these differences were related to the volume of distribution of insulin, insulin clearance, or both.Design Forty‐four women were studied between 33 and 35 weeks’ gestation using an insulin‐modified FSIVGTT. Specific insulin was assayed with an enzyme‐linked immunosorbent assay. Insulin sensitivity was calculated using the minimal model and the homeostasis model assessment (HOMA). The volume of distribution and clearance of insulin were calculated from measurements between 2 and 155 min after insulin modification using a one‐compartment model.Results In accordance with the method for deriving the volume of distribution, there was a significant negative correlation between the increment in insulin concentration and the volume of distribution (rho = −0·92, P < 0·0001). The insulin increment was also related negatively to the clearance of insulin (rho = −0·88, P < 0·0001). There was a significant correlation between the volume of distribution and both the insulin sensitivity index (rho = 0·56, P < 0·0001) and HOMA‐%S (rho = 0·30, P= 0·048), and between the clearance of insulin and both the insulin sensitivity index (rho = 0·83, P < 0·0001)) and HOMA‐%S (rho = 0·34, P= 0·025).Conclusion The different time‐concentration profiles of plasma insulin resulted from differences in the volume of distribution and clearance of insulin. There was a correlation between insulin kinetics and the insulin sensitivity index. Further research is required to investigate possible mechanisms by which insulin kinetics may be related to insulin sensitivity.
Predictors of lipoprotein(a) levels in a European and South Asian population in the Newcastle Heart Project
Authors: Tavridou A. , Unwin N. , Bhopal R. , Laker M. F. 
Published: July 2003

AbstractBackground Understanding of the higher susceptibility of South Asians to coronary heart disease is limited. One explanation is the combination of high prevalence of insulin resistance with higher lipoprotein(a) levels.Materials and methods Lipoprotein(a) levels and genotypes in three South Asian groups aged 25–74 years (Indian, Pakistani, Bangladeshi) were compared with a European population in a cross‐sectional study. Biochemical measurements included lipids, apolipoprotein A1 and B, glucose, insulin and fibrinogen. Insulin sensitivity was calculated using the homoeostasis model assessment method (HOMA).Results There was no significant difference in lipoprotein(a) levels between South Asian and European men. South Asian women combined had higher lipoprotein(a) levels than European women, a difference probably resulting from higher lipoprotein(a) levels in Pakistani women compared with Indian and Bangladeshi women. Fasting insulin and HOMA were negatively associated with Lp(a) in South Asians though the associations were statistically significant only in men. There were only modest associations between most cardiovascular risk factors and Lp(a). Twenty‐seven apolipoprotein(a) size alleles were detected in the three South Asian groups ranging from 16 to 43 kringle‐IV repeats. The apolipoprotein(a) size polymorphism explained 23% of the variability in lipoprotein(a) levels in South Asians.Conclusions There were few nongenetic predictors of lipoprotein(a) levels in South Asians and Europeans. The lack of difference in Lp(a) between the South Asian and European men and the fact that differences between the women seemed to be confined to the Pakistani group offer little support to the hypothesis that higher Lp(a) levels contribute to the increased risk of heart disease in South Asians. Our findings do not support the hypothesis that susceptibility to heart disease in South Asians results from a combination of high insulin resistance and high Lp(a) levels.
The evolution of HOM‐C homeoboxes in the Dipteran family Drosophilidae
Authors: DeSalle R. , Branham M. A. , O'Grady P. , Gatesy J. 
Published: July 2003

AbstractForty‐five new Homeotic Complex (HOM‐C) homeobox sequences from six species of Drosophilidae (Drosophila heteroneura, D. adiastola, Zaprionus vittiger, Chymomyza amoena, Scaptodrosophila pattersoni and Hirtodrosophila pictiventris) were obtained using a PCR‐cloning method. These new homeoboxes are from the labial, proboscipedia, Deformed, Sex combs reduced, fushi tarazu, Antennapedia, Ultrabithorax, abdominal‐A and Abdominal‐B genes. Phylogenetic signal in the homeobox sequences was assessed and several aspects of sequence evolution were examined. In particular, codon bias was examined and found to exist between the drosophilid species examined here and Anopheles gambiae outgroup sequences. In addition, different patterns of codon bias were detected in homeoboxes interrupted with introns when compared to homeoboxes that are uninterrupted.
Stress response in a juvenile hormone‐deficient Drosophila melanogaster mutant apterous56f
Authors: Gruntenko N. E. , Chentsova N. A. , Andreenkova E. V. , Bownes M. , Segal D. , Adonyeva N. V. , Rauschenbach I. Yu 
Published: July 2003

AbstractThe apterous56f (ap56f) mutation leads to increases in juvenile hormone (JH) degradation levels and JH‐esterase makes a greater contribution to the increase than JH‐epoxide hydrolase. Dopamine levels in ap56f females, but not males, are higher than in wild‐type. JH treatment of ap56f and wild‐type females decreases their dopamine levels. ap56f females, but not males, produce less progeny. Survival under heat stress is dramatically decreased in ap56f females, but not males. ap56f flies show a stress reaction, as judged by changes in tyrosine decarboxylase and JH‐hydrolysing activities, dopamine levels and fertility, but its intensity in the mutant females, but not males, differs significantly from wild‐type. Thus, the ap56f mutation causes dramatic changes in female, but not male, metabolism and fitness.
Characterization of an intestinal mucin from the peritrophic matrix of the diamondback moth, Plutella xylostella
Authors: Sarauer B. L. , Gillott C. , Hegedus Dwayne 
Published: July 2003

AbstractThe peritrophic matrix (PM) of Plutella xylostella larvae was found to contain twelve integral and eighteen loosely associated proteins. An antiserum against Mamestra configurata integral PM proteins cross‐reacted with several P. xylostella PM proteins and was used to isolate a partial cDNA encoding an insect intestinal mucin (PxIIM). PxIIM was expressed primarily in the larval midgut. The deduced protein sequence of the partial cDNA contained three potentially glycosylated, mucin‐like domains and six cysteine‐rich chitin‐binding domains (CBDs). An additional chitin‐binding domain was proposed to reside at the amino terminus of the protein based on comparison with other IIM. The organization of mucin domains and CBDs exhibited features, including an internal triplet of regularly spaced CBDs and a carboxyl terminal CBD with two additional conserved cysteine residues, that were found to be common to other lepidopteran IIMs.
Fat body expressed yolk protein genes in Hyphantria cunea are related to the YP4 follicular epithelium yolk protein subunit gene of pyralid moths
Authors: Cheon H. M. , Kim H. J. , Yun C. Y. , Lee H. J. , Lee I. H. , Shirk P. D. , Seo S. J. 
Published: July 2003

AbstractcDNA clones for two of the yolk proteins, YP1 and YP2, produced by the fat body of the moth, Hyphantria cunea, were sequenced and found to be homologous to the follicular epithelium yolk proteins of pyralid moths. Both cDNA clones coded for polypeptides of 290 residues and the deduced amino acid sequence identity between YP1 and YP2 was very high (79.0%). Analysis of the secondary structure of the predicted polypeptides suggests that YP1 and YP2 do not form heteromeric proteins because of differences in secondary structure due to the lack of alpha helices in YP1. Northern blot analysis showed that the transcripts for YP1 (1.2 kb) and YP2 (1.1 kb) were present primarily in the female fat body with only trace levels detectable in the ovary of the adult female. In a developmental study, the YP1 and YP2 transcripts were first detectable in 10‐day‐old pupae and increased into the adult stage. These results suggest that the YP1 and YP2 genes in H. cunea have been recruited to replace the vitellogenin gene as the primary source of yolk proteins. During this process they have acquired a modified pattern of expression that is different from homologous genes reported in pyralid moths. The assessment of the evolution of proteinaceous yolk in these moths should serve as an excellent model for the evolution of gene recruitment.
Heat stress affects oogenesis differently in wild‐type Drosophila virilis and a mutant with altered juvenile hormone and 20‐hydroxyecdysone levels
Authors: Gruntenko N. E. , Bownes M. , Terashima J. , Sukhanova M. Zh. , Raushenbach I. Yu 
Published: July 2003

AbstractThe link between reproduction and environmental signals is poorly understood at the physiological, genetic and molecular levels. We describe a mutant strain of Drosophila virilis that has altered responses to heat stress. Heat stress in wild‐type females results in oocyte maturation delays, degradation of early vitellogenic egg chambers, inhibition of yolk protein gene expression in follicle cells and accumulation of mature oocytes. The mutant females have increased levels of ecdysteroids and decreased juvenile hormone degradation, and show all of the heat‐stress‐induced reproductive effects observed in wild‐type flies, without exposure to heat stress. During oogenesis in mutant females following heat stress there is an increase in early vitellogenic oocyte degradation and some degradation of late egg chambers. 20‐Hydroxyecdysone levels, but not juvenile hormone degradation, change following heat stress in mutant females.
Swarming motility in undomesticated Bacillus subtilis
Authors: Kearns Daniel B. , Losick Richard 
Published: July 2003

SummarySwarming motility was identified and characterized in an undomesticated strain of Bacillus subtilis. Rapid surface migration was preceded by a cell density‐dependent lag period, which could be eliminated if actively swarming cells were used as the inoculum. The leading edge of the swarm was characterized by multicellular rafts of highly flagellated cells. Flagellum biosynthesis and surfactant production were required for swarming. Swarming was not found in any of several standard laboratory strains. Laboratory strains are characteristically unable to produce surfactant, but such a strain remained unable to swarm even when surfactant was provided by extracellular complementation. We conclude that robust swarming is a feature of undomesticated B. subtilis and that this behaviour has been lost or attenuated in laboratory strains through the accumulation of multiple genetic defects.
MxiK and MxiN interact with the Spa47 ATPase and are required for transit of the needle components MxiH and MxiI, but not of Ipa proteins, through the type III secretion apparatus of Shigella flexneri
Authors: Jouihri Noureddine , Sory Marie‐Paule , Page Anne‐Laure , Gounon Pierre , Parsot Claude , Allaoui Abdelmounaaïm 
Published: July 2003

SummaryThe type III secretion (TTS) pathway is used by numerous Gram‐negative pathogens to inject virulence factors into eukaryotic cells. The Shigella flexneri TTS apparatus (TTSA) spans the bacterial enveloppe and its assembly requires the products of approximately 20 mxi and spa genes. We present a functional analysis of the mxiK, mxiN and mxiL genes. Inactivation of mxiK and mxiN, but not mxiL, resulted in the assembly of a non‐functional TTSA that lacked the outer needle. The amounts of needle components MxiH and MxiI were drastically reduced in mxiK and mxiN mutants and in the secretion defective spa47 mutant, indicating that MxiH and MxiI are degraded if they do not transit through the TTSA. Remarkably, expression of MxiH‐His in the mxiN mutant and MxiI‐His in the mxiK mutant restored assembly of a functional TTSA, as shown by the ability of these strains to enter into epithelial cells and to secrete Ipa proteins in response to activation by Congo red. Using a two‐hybrid screen in yeast and immunoprecipitation assays from S. flexneri extracts, we identified interactions between MxiK and Spa33 and Spa47 and between MxiN and Spa33 and Spa47. These results suggest that transit of the needle components MxiH and MxiI through the TTSA involves the concerted action of the cytoplasmic proteins Spa47, Spa33, MxiK and MxiN. They also show that neither MxiK nor MxiN are absolutely required for secretion of Ipa proteins, provided that the TTSA is correctly assembled.
LexA‐independent DNA damage‐mediated induction of gene expression in Myxococcus xanthus
Authors: Campoy Susana , Fontes Marta , Padmanabhan S. , Cortés Pilar , Llagostera Montserrat , Barbé Jordi 
Published: July 2003

Summary Myxococcus xanthus, a member of the Proteobacteria delta‐class, has two independent recA genes, recA1 and recA2, but only recA2 is DNA damage‐inducible. The lexA gene has been isolated from M. xanthus by PCR amplification with oligonucleotides designed after sequence identification by tblastn analysis of its genome at the Cereon Microbial Sequence Database. The M. xanthus purified LexA protein is shown to bind specifically to the consensus sequence CTRHAMRYBYGTTCAGS present upstream of lexA and recA2. A degenerate copy of this motif but with important differences can be identified in the region upstream of the recA1 gene. A knock‐out lexA(Def) mutant that has been generated does not differ significantly from wild type in morphology, growth rate, light‐induced carotenogenesis or development. Using transcriptional lacZ fusions and quantitative RT‐PCR analysis, it has been demonstrated that expression of both lexA and recA2 genes is constitutive in the lexA(Def) mutant, whereas the transcription of the DNA damage non‐inducible recA1 gene is not affected in this strain. recN and ssb, whose expression in Escherichia coli are LexA‐regulated, are induced by DNA damage in the M. xanthus lexA(Def) mutant. These data reveal the existence of different regulatory mechanisms for DNA damage‐inducible genes in bacteria belonging to different phyla.
Regulation of the expression of gas vesicle genes in Haloferax mediterranei: interaction of the two regulatory proteins GvpD and GvpE
Authors: Zimmermann Peter , Pfeifer Felicitas 
Published: July 2003

SummaryThe gas vesicle formation in Haloferax mediterranei occurs in the stationary growth phase and involves the 14 genes mc‐gvpACNO and mc‐gvpDEFGHIJKLM. The appearance of the two regulatory proteins GvpD and GvpE, and also of GvpF, was investigated during the growth of H. mediterranei. GvpD was only found during the stationary growth phase, GvpE was present from the late exponential to stationary growth phase, and GvpF was present only during the exponential growth, although the three genes were co‐transcribed. The impact of GvpD and GvpE on the activity of the promoter of the mc‐gvpACNO gene cluster encoding the gas vesicle structural proteins was analysed in H. volcanii transformants containing the mc‐gvpA gene or a fusion of the mcA promoter with the bgaH reading frame encoding a halobacterial β‐galactosidase as reporter. The experiments proved that GvpE is a transcriptional activator, whereas GvpD is involved in the repression. Protein–protein affinity chromatography was used to search for putative binding partners of GvpD and GvpE. Both proteins were synthesized in Escherichia coli as his‐tagged proteins, isolated under denaturing conditions and refolded by dialysis against buffers containing decreasing urea and increasing KCl concentrations up to 2.5 M. The Ni‐NTA matrix tagged with GvpD‐his or GvpE‐his was incubated with soluble proteins of gas vesicle producing H. mediterranei cells. A 21 kDa protein was purified using the matrix tagged with GvpD‐his which proved to be GvpE by Western analysis. Vice versa, GvpD was purified using the GvpE‐his‐Ni‐NTA matrix. These results strongly suggested that GvpD and GvpE were able to interact and might constitute a regulatory system.
Salmonella type III effectors PipB and PipB2 are targeted to detergent‐resistant microdomains on internal host cell membranes
Authors: Knodler Leigh A. , Vallance Bruce A. , Hensel Michael , Jäckel Daniela , Finlay B. Brett , Steele‐Mortimer Olivia 
Published: July 2003

SummaryThe intracellular pathogen, Salmonella enterica, translocates type III effectors across its vacuolar membrane into host cells. Herein we describe a new Salmonella effector, PipB2, which has sequence similarity to another type III effector, PipB. In phagocytic cells, PipB2 localizes to the Salmonella‐containing vacuole (SCV) and tubular extensions from the SCV, Salmonella‐induced filaments (Sifs). We used the specific targeting of PipB2 in macrophages to characterize Sifs in phagocytic cells for the first time. In epithelial cells, PipB2 has a unique localization pattern, localizing to SCVs and Sifs and additionally to vesicles at the periphery of infected cells. We further show that the N‐terminal 225‐amino‐acid residues of PipB2 are sufficient for type III translocation and association with SCVs and Sifs, but not peripheral vesicles. Subcellular fractionation demonstrated that both PipB and PipB2 associate with host cell membranes and resist extraction by high salt, high pH and to a significant extent, non‐ionic detergent. Furthermore, PipB and PipB2 are enriched in detergent‐resistant microdomains (DRMs), also known as lipid rafts, present on membranes of SCVs and Sifs. The enrichment of Salmonella effectors in DRMs on these intracellular membranes probably permits specific interactions with host cell molecules that are concentrated in these signalling platforms.
The fimbrial adhesin F17‐G of enterotoxigenic Escherichia coli has an immunoglobulin‐like lectin domain that binds N‐acetylglucosamine
Authors: Buts Lieven , Bouckaert Julie , De Genst Erwin , Loris Remy , Oscarson Stefan , Lahmann Martina , Messens Joris , Brosens Elke , Wyns Lode , De Greve Henri 
Published: July 2003

SummaryThe F17‐G adhesin at the tip of flexible F17 fimbriae of enterotoxigenic Escherichia coli mediates binding to N‐acetyl‐β‐d‐glucosamine‐presenting receptors on the microvilli of the intestinal epithelium of ruminants. We report the 1.7 Å resolution crystal structure of the lectin domain of F17‐G, both free and in complex with N‐acetylglucosamine. The monosaccharide is bound on the side of the ellipsoid‐shaped protein in a conserved site around which all natural variations of F17‐G are clustered. A model is proposed for the interaction between F17‐fimbriated E. coli and microvilli with enhanced affinity compared with the binding constant we determined for F17‐G binding to N‐acetylglucosamine (0.85 mM−1). Unexpectedly, the F17‐G structure reveals that the lectin domains of the F17‐G, PapGII and FimH fimbrial adhesins all share the immunoglobulin‐like fold of the structural components (pilins) of their fimbriae, despite lack of any sequence identity. Fold comparisons with pilin and chaperone structures of the chaperone/usher pathway highlight the central role of the C‐terminal β‐strand G of the immunoglobulin‐like fold and provides new insights into pilus assembly, function and adhesion.