bluuebunny/crossref_metadata_2025 huggingface dataset:
Symptomatic improvement with one‐year cisapride treatment in neuropathic chronic intestinal dysmotility.
Authors: Camilleri M , Balm RK , Zinsmeister AR
Published: June 2006

AIM: To assess the efficacy of a prokinetic agent in the long‐term treatment of chronic intestinal dysmotility and the influence of extrinsic denervation. METHODS: We assessed symptoms, compliance and untoward effects in an open, 1‐year trial of cisapride, 20 mg t.d.s., in 37 patients with neuropathic forms of chronic intestinal dysmotility. Patients' autonomic function had previously been characterized; effects of cisapride at 12 weeks in a placebo‐controlled trial were previously reported. RESULTS: Seventeen patients had idiopathic dysmotility, 11 had diabetes mellitus with autonomic dysfunction, five had had previous gastric surgery and four had neurological syndromes. Median medication compliance was 98.9% for the study period completed by each individual. Median duration of follow‐up was 9.5 months; 20 patients completed 1 year of treatment, and 27 of 37 at least 6 months of treatment; seven dropped out because of lack of benefit. Mean total symptom score was significantly reduced at the last observation relative to the entry into the trial; this was particularly the case in those patients without abdominal vagal dysfunction. One patient withdrew because of aggravation of abdominal pain. CONCLUSIONS: During an open, long‐term trial, cisapride, 20 mg t.d.s., provided continued symptomatic relief to patients with chronic intestinal dysmotility, particularly those without vagal neuropathy.
Prescribed doses of inhaled steroids in Dutch children: too little or too much, for too short a time
Authors: Schirm Eric , De Vries Tjalling W. , Tobi Hilde , Van Den Berg Paul B. , De Jong‐van den Berg Lolkje T. W.
Published: June 2006

Aims

To investigate the dosage and duration of inhaled steroids prescribed to children and to compare the prescribed doses with recommended doses for the treatment of asthma in children.

Methods

For 2514 Dutch children aged 0–12 years who had used inhaled steroids in 2002, pharmacy dispensing data were obtained from the InterAction database, type of steroid (beclomethason, budesonide, fluticasone) and type of user (first time or existing) and the average prescribed doses according to age were determined and compared with the doses as recommended in the national Dutch Nederlands Huisartsen Genootschap (NHG) guideline. Furthermore, for all first‐time users the duration of therapy with inhaled steroids was determined using a Kaplan–Meier analysis.

Results

The major findings were that: (i) overall 43% of children starting inhaled steroids were prescribed doses that are half the recommended dose or less; (ii) overall 8% of the children starting inhaled steroids were prescribed doses that were twice the recommended dose or more, up to 50% in the 12‐year‐olds fluticasone group; and (iii) only 8% of the children who started with inhaled steroids used them continuously for a full year.

Conclusions

Doses of inhaled steroids for many children deviate from those recommended, with lower doses more frequently occurring than higher doses. Less than 10% of the children receive prescriptions for a prolonged period of time.
Different inflammatory cell pattern and macrophage phenotype in chronic obstructive pulmonary disease patients, smokers and non-smokers
Authors: Löfdahl J M , Wahlström J , Sköld C M
Published: June 2006

Smokers exhibit airway inflammation and increased number of alveolar macrophages (AM), but not all develop chronic obstructive pulmonary disease (COPD). We hypothesized that AMs in COPD patients have an altered functional capacity mirrored in a different phenotype. Sixteen steroid-naive COPD patients [forced expiratory volume in 1 s (FEV1) < 70% of predicted] underwent bronchoalveolar lavage (BAL). Age- and smoking-matched non-obstructive smokers (n = 10) and healthy non-smokers (n = 9) served as controls. Nine COPD patients had a BAL cell yield sufficient for flow cytometry analysis, where expression of AM cell surface markers reflecting various functions was determined. AMs from COPD patients showed decreased expression of CD86 (co-stimulation) and CD11a (adhesion) compared to smokers’ AMs (P < 0·05). Furthermore, smokers’ AMs showed lower (P < 0·05) expression of CD11a compared to non-smokers. AM expression of CD11c was higher in the COPD and smokers groups compared to non-smokers (P < 0·05). The expression of CD54 (adhesion) was lower in smokers’ AMs compared to non-smokers (P < 0·05), whereas CD16 was lower (P < 0·05) in COPD patients compared to non-smokers. The AM expression of CD11b, CD14, CD58, CD71, CD80 and human leucocyte antigen (HLA) Class II did not differ between the three groups. The AM phenotype is altered in COPD and further research may develop disease markers. The lower AM expression of CD86 and CD11a in COPD implies a reduced antigen-presenting function. Some alterations were found in smokers compared to non-smokers, thus indicating that changes in AM phenotype may be associated with smoking per se. The functional relevance of our findings remains to be elucidated.
The historic man‐made soils of the Generalife garden (La Alhambra, Granada, Spain)
Authors: Delgado R. , Martín‐García J. M. , Calero J. , Casares‐Porcel M. , Tito‐Rojo J. , Delgado G.
Published: June 2006

We studied the soils of the Patio de la Acequia garden of the Generalife, a palatial villa forming part of La Alhambra, a World Heritage Site in Granada, Spain. This garden, which is estimated to be around 700 years old, is the oldest historical garden in the Western World. The soils are man‐made cumulimollihumic‐calcaric (hypereutric, anthric) Regosols. Noteworthy amongst the main pedogenic processes, in relation to the human activities of cultivation, irrigation and tillage, are horizonation, melanization (the contents of organic carbon varied between 0.59% and 8.87%, and those of P205 extracted with citric acid between 723 mg kg−1 and 7333 mg kg−1, with maximae in the Ap horizons) and structure formation. The soil fabric, studied at the ultramicroscopic level using scanning electron microscopy, is of laminar and partition‐walls’ type in the lower horizons, depending on the microped zones. The partition‐walls’ fabrics found are different to those of the possible pre‐existing sedimentary fabrics. These are numerous lithological discontinuities and at least two burials, leading us to deduce that there have been two main stages of filling with materials in the formation of these soils. The first is Arabic‐Medieval (13th century), when the garden was created, its surface being some 50 cm below the level of the paved area of the present patio. In the deeper parts, the materials employed in the fill are similar to the in situ soils of the zone, unaffected by the buildings. The second stage is Christian (15th century to the present day). During this period the Medieval garden was gradually buried under a layer of materials from the nearby soils and/or sediments mixed with manure until the surface was only just below the level of the paved area of the patio. In this work we discuss the difficult classification of these relatively little studied soils. In spite of their being clearly related to human activity, they are not classified as Anthrosols in the FAO system (1998) because soil materials cannot be classified as anthropopedogenic or as anthropogeomorphic.
Vertical distribution and behaviour of shrimp Pandalus borealis larval stages in thermally stratified water columns: laboratory experiment and field observations
Authors: OUELLET PATRICK , ALLARD JEAN‐PIERRE
Published: June 2006

By combining field data and laboratory observations of larvae in a simulated thermal gradient, we described the ontogenetic changes in vertical distribution and behaviour of early stages of shrimp Pandalus borealis in thermally stratified water columns. Both in the laboratory and at stations in the north‐western Gulf of St Lawrence, the first two larval stages appear to actively select and maintain a position in the upper layer of warmer temperatures, within the thermocline and above the cold (<1°C) intermediate layer. Stage III larvae were distributed deeper in the water column and in colder waters than the previous two stages. Stage IV and V larvae showed the highest degree of swimming activity in the laboratory and a much wider range (from surface to ∼200 m) in vertical distribution in the field. The shift to deeper waters and settlement to the bottom habitat appears to happen after the fifth moult, at stage VI. We propose that the pattern of vertical distribution in the field reflects the adjustment of the different developmental stages to the distribution of preferred prey. The description of the ontogenetic change in the vertical distributions and movements of early stages of P. borealis should be valuable information for future attempts to model larval transport and dispersion, and for detecting settlement/recruitment areas using 3D ocean circulation models. The identification of the thermal habitat of the different larval stages and the timing for settlement at the bottom also provides important information for the development of temperature‐dependent growth models up to the first juvenile stages.
Actin‐capping protein is involved in controlling organization of actin cytoskeleton together with ADF/cofilin, profilin and F‐actin crosslinking proteins in fission yeast
Authors: Nakano Kentaro , Mabuchi Issei
Published: June 2006

Actin‐capping protein (CP) is a heterodimeric protein which is expressed in various eukaryotic cells. CP binds to the barbed end of the actin filamentsin vitroand inhibits both the association and dissociation of actin monomers at this end. However, the cellular role of CP has not been uncovered. Here we investigated the function of CP in fission yeast cells. The fission yeast CP is composed of Acp1 and Acp2. It was found that Acp2 accumulated as cortical dots at the cell ends during interphase and the mid‐region of mitotic cells, which disappeared in the absence of Acp1 or F‐actin. Acp1 and Acp2, when co‐over‐expressed, decreased F‐actin structures in cells, and cytokinesis was often interrupted in these cells. On the other hand, disruption of one of the CP genes affected the distribution of F‐actin patches at cell ends and decreased the rate of actin depolymerizationin vivo. Moreover, genetic analysis showed that CP controls actin dynamics together with ADF/cofilin and profilin. In addition, CP is likely involved in assembling the F‐actin contractile ring and F‐actin patch with F‐actin‐crosslinking proteins.
Bayesian correlation between temperature and blossom onset data
Authors: DOSE VOLKER , MENZEL ANNETTE
Published: June 2006

The recent quantification of changes in time series of phenology data with Bayesian methods has provided compelling evidence for changes during the last 20 years. In this paper we correlate the phenological observations with spring temperature time series. We provide quantitative answers to the question whether changes in temperature and phenological time series should be regarded as coherent or independent. For the three considered species snowdrops, cherry and lime tree we find factors of 1.05, 2.19 and 3.26, respectively, in favor of coherence. The functional behavior and the trend in the temperature time series are presented. They amount to 0.15°C yr−1 for the January–March average, 0.09°C yr−1 for February–April and 0.1°C yr−1 for March–May in 2002. In addition, we compare blossom trends for the coherent and independent hypotheses and find that the transition from trend values slightly positive before 1970 to strongly negative at present becomes sharper as the temperature data are included in the analysis.
Fingerprints of environmental change on the rare mediterranean flora: a 115‐year study
Authors: LAVERGNE SÉBASTIEN , MOLINA JAMES , DEBUSSCHE MAX
Published: June 2006

We empirically assessed the long‐term changes in the rare species assemblage of a Mediterranean flora, in terms of species life history traits, niche and biogeographic features, and taxonomic groups. We used a 115‐year historical record of ca. 2100 plant species occurrences in a 6250 km2region in Mediterranean France. Species were assigned to two classes of regional abundance for the years 1886 and 2001 (rare species, i.e. exhibiting one or two occurrences vs. nonrare species), and to three classes of abundance changes during 1886–2001 (decreasing/extinct, stable, increasing/immigrant). Then, we tested whether species regional abundance and species abundance change were related to their morphological and life‐history traits (life form, perenniality, height, dispersal agent, pollination mode), niche and biogeographic features (habitat specialization, level of endemism, biogeographic origin) and taxonomic group. The regional assemblage of rare species was not biologically random and significantly changed between 1886 and 2001. Species classified as rare in 1886 had a significantly higher rate of extinction in the study region during 1886–2001. The highest rate of regression/extinction was found among hydrophyte and/or water‐dispersed rare species, and among annual rare species. However, herbaceous perennial, tree and wind‐dispersed rare species significantly increased in abundance during 1886–2001. Rare species with Eurosiberian distributions, occurring at the southern margin of their range in the study region, dramatically declined or went extinct in the region during 1886–2001; whereas rare species with Mediterranean affinities remained significantly stable. We also found strong evidence for taxonomic patterns in species abundance and abundance changes from 1886 to 2001. The long‐term biological changes documented here in the rare species assemblage of a Mediterranean flora are consistent with the predicted consequences of climate and land use changes currently occurring in the Mediterranean Basin. With the potential decline or even extinction of entire taxa and the loss of southern ecotypes of widespread Eurosiberian species, both evolutionary history and speciation potential of the Mediterranean Region could be strongly altered in future decades.
Increasing CO2 from subambient to elevated concentrations increases grassland respiration per unit of net carbon fixation
Authors: WAYNE POLLEY H. , MIELNICK PATRICIA C. , DUGAS WILLIAM A. , JOHNSON HYRUM B. , SANABRIA JOAQUIN
Published: June 2006

Respiration (carbon efflux) by terrestrial ecosystems is a major component of the global carbon (C) cycle, but the response of C efflux to atmospheric CO2 enrichment remains uncertain. Respiration may respond directly to an increase in the availability of C substrates at high CO2, but also may be affected indirectly by a CO2‐mediated alteration in the amount by which respiration changes per unit of change in temperature or C uptake (sensitivity of respiration to temperature or C uptake). We measured CO2 fluxes continuously during the final 2 years of a 4‐year experiment on C3/C4 grassland that was exposed to a 200–560 μmol mol−1 CO2 gradient. Flux measurements were used to determine whether CO2 treatment affected nighttime respiration rates and the response of ecosystem respiration to seasonal changes in net C uptake and air temperature. Increasing CO2 from subambient to elevated concentrations stimulated grassland respiration at night by increasing the net amount of C fixed during daylight and by increasing either the sensitivity of C efflux to daily changes in C fixation or the respiration rate in the absence of C uptake (basal ecosystem respiration rate). These latter two changes contributed to a 30–47% increase in the ratio of nighttime respiration to daytime net C influx as CO2 increased from subamient to elevated concentrations. Daily changes in net C uptake were highly correlated with variation in temperature, meaning that the shared contribution of C uptake and temperature in explaining variance in respiration rates was large. Statistically controlling for collinearity between temperature and C uptake reduced the effect of a given change in C influx on respiration. Conversely, CO2 treatment did not affect the response of grassland respiration to seasonal variation in temperature. Elevating CO2 concentration increased grassland respiration rates by increasing both net C input and respiration per unit of C input. A better understanding of how C efflux varies with substrate supply thus may be required to accurately assess the C balance of terrestrial ecosystems.
Arterial and venous thrombosis in rare congenital bleeding disorders: a critical review
Authors: GIROLAMI A. , RUZZON E. , TEZZA F. , SCANDELLARI R. , VETTORE S. , GIROLAMI B.
Published: June 2006

Summary.  A thorough review of the literature and of personal files has allowed the gathering of 81 patients with rare congenital bleeding disorders and thrombotic phenomena. Sixteen of these patients had congenital afibrinogenemia, eight involved factor V deficiency, 20 factor VII defects, 33 factor XI deficiencies and only one, a factor XIII defect. Altogether 42 patients showed arterial thrombosis (myocardial infarction [MI] in 28 cases; ischemic stroke in 4; arterial occlusion in 8; 2 patients with disseminated intravascular coagulation (DIC)). Ages varied between 13 and 74. Twenty‐two patients were males and 16 females. In four cases, sex was not reported. There were three fatalities: two after a MI and one because of heart failure. With regard to venous thrombosis: 9 patients had pulmonary embolism, 15 patients had deep vein thrombosis, 9 patients had both pulmonary embolism and deep vein thrombosis; 1 patient had superficial vein thrombosis, whereas, 5 cases had an unusual site venous thrombosis (two portal systems, two cerebral sinuses, one inferior vena cava) for a total of 39 cases. Age varied between 3 and 86. In this case, 20 patients were males and 17 were females. In two cases, sex was not reported. There were three fatalities: two because of pulmonary embolism and one because of inferior vena cava thrombosis. The fact that thrombosis has never been described in patients with factor II or factor X seems to underscore the central antithrombotic role that these two factors have in the coagulation system.
A T2 cytokine environment may not limit T1 responses in human immunodeficiency virus patients with a favourable response to antiretroviral therapy
Authors: Price Patricia , Keane Niamh M. , Lee Silvia , Lim Andrew F. Y. , McKinnon Elizabeth J. , French Martyn A.
Published: June 2006

Low‐level production of interferon‐γ (IFN‐γ) marks human immunodeficiency virus (HIV)‐induced immunodeficiency and has been ascribed to a bias towards T2 cytokines. This was investigated in two cross‐sectional studies of HIV patients who were immunodeficient when they began antiretroviral therapy (ART) and had stable increases in CD4 T‐cell counts. Blood leucocytes were assessed unstimulated or after stimulation with cytomegalovirus (CMV), anti‐CD3 or mitogen. IFN‐γ and interleukin (IL)‐5 responses were initially assessed by enzyme‐linked immunosorbent spot‐forming cell assay (ELISPOT) and enzyme‐linked immunosorbent assay (ELISA). We then adopted a sensitive reverse transcription–polymerase chain reaction (RT–PCR) system to assess IFN‐γ, IL‐5, IL‐4 and IL‐4δ2 (an inhibitory splice variant of IL‐4) mRNA. The results were correlated with putative serological markers of a T1 [lymphocyte activation gene‐3 (LAG‐3), CD26] or a T2 [CD30, immunoglobulin E (IgE)] cytokine environment. IL‐5 production and IgE levels were elevated in patients. IgE levels did not correlate with IFN‐γ, but showed an inverse correlation with IL‐5 released in culture (P = 0·05). The levels of IL‐4, IFN‐γ, IL‐5 and IL‐4δ2 mRNA were correlated after anti‐CD3 stimulation, where IL‐5 was the best predictor of IFN‐γ mRNA (P = 0·006). Weak positive correlations were evident between CD30 and cytokine mRNA levels, whilst IgE correlated inversely with IL‐4, IL‐4δ2, IL‐5 and IFN‐γ mRNA levels. These analyses provide no evidence for an inverse relationship between T1 and T2 cytokine responses in HIV patients, but suggest that the elevation of IgE marks low cytokine responses.
T cells developing in fetal thymus of T‐cell receptor α‐chain transgenic mice colonize γδ T‐cell‐specific epithelial niches but lack long‐term reconstituting potential
Authors: Leandersson Karin , Jaensson Elin , Ivars Fredrik
Published: June 2006

The γδ T cells generated during mouse fetal development are absolutely dependent on their invariant T‐cell receptors (TCRs) for their function. However, there is little information on whether the epithelial homing properties of fetal T cells might also be developmentally induced by factors unrelated to TCR specificity. We have previously described TCR α‐chain transgenic (2B4 TCR‐α TG) mice, in which the transgenic TCR α‐chain is expressed early, already at embryonic day 14 (E14). These mice have a large population of ‘γδ T‐cell‐like’ CD4– CD8– (double‐negative; DN) αβ T cells, some of which develop during E14–E18 contemporarily to intraepithelial lymphocytes (IELs) expressing invariant TCR‐γδ. Using the 2B4 TCR‐α TG mouse model we have been able to more precisely study the impact of a variant TCR expression on IEL development and homing. In this study we show that TCR‐α TG and TCR‐α TG crossed to TCR‐δ‐deficient mice (TCR‐α TG × TCR‐δ–/–) carry TG TCR‐α+ dendritic epidermal T cells (DETCs) and TCR‐α TG+ IELs in the small intestine. The TG+ DETCs develop and seed the epidermis with similar kinetics as Vγ5+ DETCs of normal mice, in contrast to the TCR‐αβ+ DETCs found in TCR‐δ–/– mice. However, whereas the intestinal TCR‐α TG+ IELs persist in old mice (> 20 months), the TCR‐α TG+ DETCs do not. The data in this study indicate that the timing of TCR expression and thereby development during ontogeny regulates the specific homing potential for fetal T cells but not their subsequent functions and properties.
Hepatitis C – contamination of toothbrushes: myth or reality?
Authors: Lock G. , Dirscherl M. , Obermeier F. , Gelbmann C. M. , Hellerbrand C. , Knöll A. , Schölmerich J. , Jilg W.
Published: June 2006

Summary.  Chronic hepatitis C patients are advised not to share toothbrushes, razors, nail‐scissors or other personal articles that potentially may have been in contact with blood, with others. This study examines the contamination of toothbrushes in patients with chronic hepatitis C as a model for a possible unconventional way of transmission. In 30 patients with chronic hepatitis C, 2 mL of saliva (before and after toothbrushing) and the toothbrush rinsing water after toothbrushing were tested for HCV‐RNA. Saliva before and after toothbrushing was positive for HCV‐RNA in nine (30%) and 11 patients (36.7%), respectively. Twelve of the toothbrush rinsing water specimens (40%) tested HCV‐RNA‐positive. In six of these 12 patients, the ‘native’ saliva had been negative for HCV‐RNA. Patients with HCV‐RNA‐positive toothbrush rinsing water showed no significant differences from those with negative rinsing water with respect to certain clinical, biochemical and virological parameters. In conclusion, our study demonstrates a contamination with HCV‐RNA of a considerable portion of toothbrushes used by hepatitis C patients, suggesting at least a theoretical risk of infection by sharing these objects and strengthening the recommendations to take care of a clear separation of these personal care objects between patients and their household members.
Detection of a 5′ end subgenome of hepatitis C virus terminating at nucleotide 384 in patients’ plasma and liver tissues
Authors: Shimizu Y. K. , Hijikata M. , Oshima M. , Shimizu K. , Yoshikura H.
Published: June 2006

Summary.  Quadri and Negro [Dig Liver Dis 2001; 33: 480] reported greater distribution of 5′ end genomic RNA of hepatitis C virus (HCV) over its 3′ end in the liver of patients with recurrent hepatitis C after liver transplantation. We not only confirmed their results by quantifying the 5′ end subgenomes in various specimens by using dilution and real‐time polymerase chain reaction methods, but also discovered that such subgenomes terminated at nucleotide (nt) 384 of the viral genome or in its immediate upstream. The subgenomes in the plasma uniformly, with a few exceptions, ended at this position, while those in the liver more heterogeneously at various points upstream of nt 384. Subgenome populations ending some points in the downstream of nt 384 were not detected. The amount of the 5′ end subgenome, while fluctuating during the clinical course of the patients, exceeded that of the longer sized HCV genomes which included the intact genome, and, when the relative ratio of the 5′ end subgenome increased, the amount of longer sized HCV RNA tended to decrease, suggesting a suppressive effect of the 5′ end subgenome on viral replication.
Improved outcome of chronic hepatitis B after heart transplantation by long‐term antiviral therapy
Authors: Potthoff A. , Tillmann H. L. , Bara C. , Deterding K. , Pethig K. , Meyer S. , Haverich A. , Böker K. H. W. , Manns M. P. , Wedemeyer H.
Published: June 2006

Summary.  Chronic hepatitis B progresses to cirrhosis in the majority of immunosuppressed patients. The outcome of long‐term antiviral therapy in HBV‐infected organ transplant recipients is unknown. In 1996, we included 20 heart transplant (HT) recipients in a pilot trial to treat chronic hepatitis B with famciclovir. At that time, bridging fibrosis or cirrhosis was evident in 15 individuals (75%). From 1998 onwards, patients were switched to lamivudine in case of primary or secondary virological nonresponse to famciclovir. Adefovir or tenofovir became available at our centre for HT recipients in 2002. After 103 months, one patient was still on famciclovir showing a complete virological response. Sixteen patients were switched to lamivudine after 0.5–4 years of famciclovir therapy. Six of those showed a long‐term response to lamivudine therapy lasting for up to 7 years. Lamivudine resistance developed in the remaining 10 patients (63%), in 4 of them successful rescue therapy (adefovir n = 3, tenofovir n = 1) could be initiated. Only one hepatocellular carcinoma developed, which was successfully treated by locoregional ablative therapy. Nine patients died (45%), with lamivudine‐resistance‐related liver failure as the cause of death in five cases. Significant improvement of Ishak fibrosis scores could be demonstrated in six of the seven patients with more than two sequential liver biopsies available. Long‐term antiviral therapy of chronic hepatitis B can lead to regression of liver cirrhosis in patients after organ transplantation, unless viral resistance occurs. This study demonstrates the urgent need for further antivirals to overcome antiviral resistance.
Global migration patterns in the fungal wheat pathogen Phaeosphaeria nodorum
Authors: STUKENBROCK EVA H. , BANKE SØREN , McDONALD BRUCE A.
Published: June 2006

The global migration patterns of the fungal wheat pathogen Phaeosphaeria nodorum were analysed using 12 microsatellite loci. Analysis of 693 isolates from nine populations indicated that the population structure of P. nodorum is characterized by high levels of genetic diversity and a low degree of subdivision between continents. To determine whether genetic similarity of populations was a result of recent divergence or extensive gene flow, the microsatellite data were analysed using an isolation‐with‐migration model. We found that the continental P. nodorum populations diverged recently, but that enough migration occurred to reduce population differentiation. The migration patterns of the pathogen indicate that immigrants originated mainly from populations in Europe, China and North America.
Role of pathogenicity island‐associated integrases in the genome plasticity of uropathogenic Escherichia coli strain 536
Authors: Hochhut Bianca , Wilde Caroline , Balling Gudrun , Middendorf Barbara , Dobrindt Ulrich , Brzuszkiewicz Elzbieta , Gottschalk Gerhard , Carniel Elisabeth , Hacker Jörg
Published: June 2006

The genome of uropathogenic Escherichia coli isolate 536 contains five well‐characterized pathogenicity islands (PAIs) encoding key virulence factors of this strain. Except PAI IV536, the four other PAIs of strain 536 are flanked by direct repeats (DRs), carry intact integrase genes and are able to excise site‐specifically from the chromosome. Genome screening of strain 536 identified a sixth putative asnW‐associated PAI. Despite the presence of DRs and an intact integrase gene, excision of this island was not detected. To investigate the role of PAI‐encoded integrases for the recombination process the int genes of each unstable island of strain 536 were inactivated. For PAI I536 and PAI II536, their respective P4‐like integrase was required for their excision. PAI III536 carries two integrase genes, intA, encoding an SfX‐like integrase, and intB, coding for an integrase with weak similarity to P4‐like integrases. Only intB was required for site‐specific excision of this island. For PAI V536, excision could not be abolished after deleting its P4‐like integrase gene but additional deletion of the PAI II536‐specific integrase gene was required. Therefore, although all mediated by P4‐like integrases, the activity of the PAI excision machinery is most often restricted to its cognate island. This work also demonstrates for the first time the existence of a cross‐talk between integrases of different PAIs and shows that this cross‐talk is unidirectional.
Pathogenicity island integrase cross‐talk: a potential new tool for virulence modulation
Authors: Manson Janet M. , Gilmore Michael S.
Published: June 2006

Instability and excision of pathogenicity islands (PAIs) have already been described in Escherichia coli 536. In this edition of Molecular Microbiology, Bianca Hochhut and colleagues from the University of Würzburg in Germany have shown that the instability of four of the E. coli 536 PAIs is mediated by a P4‐type integrase encoded within the specific PAI by a site‐specific recombination mechanism. The integrase encoded on PAI II536 is able to mediate excision and integration of both PAI II536, and also PAI V536. The att sites of both these PAIs have a region of sequence similarity, which is also found in several other PAIs and in tRNA genes in several bacterial species. The cross‐PAI activity of this integrase (IntPAI II) suggests that it plays an important role in both genome evolution and horizontal transfer of pathogenicity elements, possibly even across species barriers. Deletion of PAIs that carry genes for adhesins and other traits might lead to a phase variation‐like phenomenon. Differential regulation of integrase activity or production might add a further level of fine‐tuning during bacterial infection.
Different genetic programmes within identical bacteria under identical conditions: the phenomenon of bistability greatly modifies our view on bacterial populations
Authors: Graumann Peter L.
Published: June 2006

Two different behavioural or developmental patters can operate within a single bacterial population in which all of the cells are exposed to the same environmental conditions. Investigations of single cells using green fluorescent protein reveal that a bacterial population can be composed of two distinct fractions in different physiological states, and that cells can even switch between states. Such behaviour, termed ‘bistability’, can occur even in exponentially growing populations, in which cells have always been regarded as behaving almost identically and having the same pattern of gene expression. In this issue of Molecular Microbiology, Dubnau and Losick review four examples of such bistable populations found in two different bacterial species, and explain why this behaviour makes sense. These investigations have established the new concept of genetically identical cells that behave differently, which will profoundly change how we view bacterial populations.
A putative novel role for plant defensins: a defensin from the zinc hyper‐accumulating plant, Arabidopsis halleri, confers zinc tolerance
Authors: Mirouze Marie , Sels Jan , Richard Odile , Czernic Pierre , Loubet Stéphanie , Jacquier Amaury , François Isabelle E.J.A. , Cammue Bruno P.A. , Lebrun Michel , Berthomieu Pierre , Marquès Laurence
Published: June 2006

The metal tolerance of metal hyper‐accumulating plants is a poorly understood mechanism. In order to unravel the molecular basis of zinc (Zn) tolerance in the Zn hyper‐accumulating plant Arabidopsis halleri ssp. halleri, we carried out a functional screening of an A. halleri cDNA library in the yeast Saccharomyces cerevisiae to search for genes conferring Zn tolerance to yeast cells. The screening revealed four A. halleri defensin genes (AhPDFs), which induced Zn but not cadmium (Cd) tolerance in yeast. The expression of AhPDF1.1 under the control of the 35S promoter in A. thaliana made the transgenic plants more tolerant to Zn than wild‐type plants, but did not change the tolerance to Cd, copper (Cu), cobalt (Co), iron (Fe) or sodium (Na). Thus, AhPDF1.1 is able to confer Zn tolerance both to yeast and plants. In A. halleri, defensins are constitutively accumulated at a higher level in shoots than in A. thaliana. A. halleri defensin pools are Zn‐responsive, both at the mRNA and protein levels. In A. thaliana, some but not all defensin genes are induced by ZnCl2 treatment, and these genes are not induced by NaCl treatment. Defensins, found in a very large number of organisms, are known to be involved in the innate immune system but have never been found to play any role in metal physiology. Our results support the proposition that defensins could be involved in Zn tolerance in A. halleri, and that a role for plant defensins in metal physiology should be considered.
Cloning of two splice variants of the rice PTS1 receptor, OsPex5pL and OsPex5pS, and their functional characterization using pex5‐deficient yeast and Arabidopsis
Authors: Lee Jung Ro , Jang Ho Hee , Park Jin Ho , Jung Ji Hyun , Lee Seung Sik , Park Soo Kwon , Chi Yong Hun , Moon Jeong Chan , Lee Young Mee , Kim Sun Young , Kim Jae‐Yean , Yun Dae‐Jin , Cho Moo Je , Lee Kyun Oh , Lee Sang Yeol
Published: June 2006

Using the rice PEX14 cDNA as a bait in a yeast two‐hybrid assay, two splice variants of the type I peroxisomal targeting signal (PTS1) receptor, OsPex5pL and OsPex5pS, were cloned from a pathogen‐treated rice leaf cDNA library. The proteins were produced from a single gene by alternative splicing, which generated a full‐length variant, OsPEX5L, and a variant that lacked exon 7, OsPEX5S. OsPex5pL contained 11 copies of the pentapeptide motif WXXXF/Y in its N‐terminus, and seven tetratricopeptide repeats in its C‐terminus. Expression of OsPEX5L and OsPEX5S predominantly occurred in leaf tissues, and was induced by various stresses, such as exposure to the pathogen Magnaporthe grisea, and treatment with fungal elicitor, methyl viologen, NaCl or hydrogen peroxide. The Arabidopsis T‐DNA insertional pex5 mutant, Atpex5, which does not germinate in the absence of sucrose and was resistant to indole‐3‐butyric acid (IBA), was perfectly rescued by over‐expression of OsPex5pL, but not by OsPex5pS. Using transient expression of OsPex5pL and OsPex5pS in the Atpex5 mutant, we show that OsPex5pL translocates both PTS1‐ and PTS2‐containing proteins into the peroxisome by interacting with OsPex7p, whereas OsPex5pS is involved only in PTS1‐dependent import in Arabidopsis.
Pseudomonas syringae effector AvrPtoB suppresses basal defence in Arabidopsis
Authors: De Torres Marta , Mansfield John W. , Grabov Nina , Brown Ian R. , Ammouneh Hassan , Tsiamis George , Forsyth Alec , Robatzek Silke , Grant Murray , Boch Jens
Published: June 2006

The virulence and avirulence activities of members of the Pseudomonas syringae HopAB family of effectors and AvrPto were examined in bean, tomato and Arabidopsis. Proteins were delivered by the RW60 strain of P. syringae pv. phaseolicola. RW60 causes a hypersensitive reaction (HR) in bean and tomato but is restricted without the HR in Arabidopsis. Dual avirulence and virulence functions in tomato and bean, respectively, were identified in virPphA homologues but only avrPtoB strongly enhanced virulence to Arabidopsis, overcoming basal defences operating against RW60. Virulence activity in both bean and Arabidopsis required regions of the C‐terminus of the AvrPtoB protein, whereas elicitation of the rapid HR in tomato, with the matching Pto resistance gene, did not. The effect of AvrPtoB on Arabidopsis was accession‐specific; most obvious in Wassilewskija (Ws‐3), intermediate in Columbia and not detectable in Niedersenz (Nd‐1) after inoculation with RW60 + avrPtoB. Analysis of crosses between Ws‐3 and Nd‐1 indicated co‐segregation for the AvrPtoB virulence function with the absence of the Nd‐1 FLS2 gene which mediates recognition of bacterial flagellin. In planta expression of AvrPtoB did not prevent the HR activated by P. syringae pv. tomato DC3000 + avrB, avrRpm1, avrRps4 or avrRpt2, but suppressed cell wall alterations, including callose deposition, characteristic of basal defence and was associated with reprogramming of the plant's transcriptional response. The success or failure of AvrPtoB in suppressing basal defences in Nd‐1 depended on the timing of exposure of plant cells to the effector and the flagellin flg22 peptide.
CUL4 associates with DDB1 and DET1 and its downregulation affects diverse aspects of development in Arabidopsis thaliana
Authors: Bernhardt Anne , Lechner Esther , Hano Perdita , Schade Verena , Dieterle Monika , Anders Marco , Dubin Manu Jody , Benvenuto Giovanna , Bowler Chris , Genschik Pascal , Hellmann Hanjo
Published: June 2006

Cullins are central scaffolding subunits in eukaryotic E3 ligases that facilitate the ubiquitination of target proteins. Arabidopsis contains at least 11 cullin proteins but only a few of them have been assigned biological roles. In this work Arabidopsis cullin 4 is shown to assemble with DDB1, RBX1, DET1 and DDB2 in vitro and in planta. In addition, by using T‐DNA insertion and CUL4 antisense lines we demonstrate that corresponding mutants are severely affected in different aspects of development. Reduced CUL4 expression leads to a reduced number of lateral roots, and to abnormal vascular tissue and stomatal development. Furthermore, cul4 mutants display a weak constitutive photomorphogenic phenotype. These results therefore assign an important function to CUL4 during plant development and provide strong evidence that CUL4 assembles together with RBX1 and DDB1 proteins to form a functional E3 ligase in Arabidopsis.
High genetic divergences indicate ancient separation of parthenogenetic lineages of the oribatid mite Platynothrus peltifer (Acari, Oribatida)
Authors: Heethoff M. , Domes K. , Laumann M. , Maraun M. , Norton R. A. , Scheu S.
Published: June 2006

Theories on the evolution and maintenance of sex are challenged by the existence of ancient parthenogenetic lineages such as bdelloid rotifers and darwinulid ostracods. It has been proposed that several parthenogenetic and speciose taxa of oribatid mites (Acari) also have an ancient origin. We used nucleotide sequences of the mitochondrial gene cytochrome oxidase I to estimate the age of the parthenogenetic oribatid mite species Platynothrus peltifer. Sixty-five specimens from 16 sites in North America, Europe and Asia were analysed. Seven major clades were identified. Within-clade genetic distances were below 2 % similar to the total intraspecific genetic diversity of most organisms. However, distances between clades averaged 56 % with a maximum of 125 %. We conclude that P. peltifer, as it is currently conceived, has existed for perhaps 100 million years, has an extant distribution that results from continental drift rather than dispersal and was subject to several cryptic speciations.
Biphonation May Function to Enhance Individual Recognition in the Dhole, Cuon alpinus
Authors: Volodina Elena V. , Volodin Ilya A. , Isaeva Irina V. , Unck Carolyn
Published: June 2006

Biphonation (two independent fundamental frequencies in a call spectrum) represents one of the most widespread nonlinear phenomena in mammalian vocalizations. Recently, the structure of biphonations was described in detail; however, their functions are poorly understood. For the dhole (Cuon alpinus), biphonic calls represent a prominent feature of vocal activity. In this species, the biphonic call is composed of two frequency components – the high‐frequency squeak and the low‐frequency yap, which also occur alone as separate calls. In this study, we test the hypothesis that the complication of call structure, resulting from the joining of these calls into the biphonic yap–squeak may enhance the potential for individual recognition in the dhole. We randomly selected for analysis 30 high‐frequency squeaks, 30 low‐frequency yaps and 30 biphonic yap–squeaks per animal from five subadult captive dholes (450 calls in total). Discriminant analysis, based on 10 squeak parameter values, showed 80.7% correct assignment to a predicted individual. For 10 yap parameters, the correct assignment was only 44.7%. However, the analysis based on 10 parameters of the biphonic yap–squeak, selected as best contributing to discrimination, showed 96.7% correct assignment to a predicted individual. The results provide strong support for the hypothesis tested showing that the joining of two independent calls into a common vocalization may function to enhance individual recognition in the dhole.
Signal Interception and the Use of Soft Song in Aggressive Interactions
Authors: Searcy William A. , Nowicki Stephen
Published: June 2006

Song sparrows, like many species of songbirds, produce songs of especially low amplitude during aggressive contests. Such ‘soft songs’ have been shown to be reliable signals of intention to attack in song sparrows. Low intensity is a paradoxical feature in a highly aggressive signal, in that it seems likely to make the signal less intimidating to an opponent. A hypothesis that resolves this paradox is that use of soft songs benefits a signaler by limiting the interception of his signals by third party receivers. Here, we test this hypothesis with respect to song sparrows and two classes of third party receivers, predators and conspecific males. We tested whether selection to avoid predation is responsible for use of soft song by examining whether male song sparrows increase production of soft song in an aggressive context when they also receive signals (alarm calls) that indicate a predator is present. We found that the proportion of soft song produced by male song sparrows was actually significantly lower in the predator context than in a control context, directly contradicting the prediction. We tested whether avoiding eavesdropping by conspecific males is a benefit of soft song by removing territory owners and simulating interactions on their territories using playback from two loudspeakers. We found that intrusions by third party males were more likely in trials in which the simulated owner countered an intruder's songs using soft songs than in trials in which the simulated owner countered with loud song, again directly contradicting the hypothesis. We conclude that limiting interception by predators and conspecific males does not provide an explanation for use of soft song by song sparrows.
Phenotypic Correlates of Scrounging Behavior in Zebra Finches: Role of Foraging Efficiency and Dominance
Authors: Beauchamp G.
Published: June 2006

In flocks, individuals can search for their own food using the producer tactic or exploit the discoveries of companions using the scrounger tactic. Models of the producer–scrounger game usually assume that tactic payoffs are independent of individual phenotypic traits. However, factors such as dominance status or foraging efficiency may constrain the use of tactics and lead to asymmetric tactic use among individuals. For instance, in flocks composed of foragers with unequal foraging efficiency, foragers that are less efficient at obtaining food are expected to rely on the scrounger tactic to a greater extent. I examined the role of foraging efficiency and dominance status as potential correlates of scrounging behavior in small aviary flocks of zebra finches (Taenopygia guttata). Individual foraging efficiency was documented in each flock in a treatment that prevented scrounging. In a subsequent treatment that allowed scrounging, higher levels of scrounging occurred as predicted in foragers with lower foraging efficiency. Dominance status was a poor predictor of tactic choice. Birds that arrived later on the foraging grid foraged less efficiently when scrounging was prevented and used scrounging to a greater extent when allowed, suggesting a link between boldness, foraging efficiency and the choice of foraging tactics in small flocks of zebra finches.
Vigilance and Collective Detection of Predators in Degus (Octodon degus)
Authors: Ebensperger Luis A. , Hurtado María José , Ramos‐Jiliberto Rodrigo
Published: June 2006

Individuals of social and partially social species typically reduce their vigilance activity when foraging in groups. As a result, per capita risk of predation decreases and individuals allocate more time to foraging and other fitness rewarding activities. Reduction of per capita risk is hypothesized to occur because there are more individuals to detect potential predators. If so, collective (i.e. total) vigilance is expected to increase with foraging group size. Increased surveillance during group foraging may occur if group members scan independently of one another, or sequentially to avoid the overlapping of their vigilance bouts. Intriguingly, such coordinated vigilance assumes that individuals monitor not only the presence, but the vigilance behaviour of group mates. We used seasonal records on time budget and grouping patterns of individually marked degus (Octodon degus), a social rodent, to examine if (a) individual vigilance decreases and/or foraging increases with group size, (b) collective vigilance increases with group size and (c) foraging degus coordinate their vigilance. When foraging, degus decreased their individual vigilance and increased their foraging time when in larger groups. Despite this, degus in larger groups increased their collective vigilance, supporting the hypothesis that socially foraging degus decrease predation risk through an improved ability to detect and escape potential predators. Additionally, patterns of collective vigilance suggested that degus scan independently of each other and so, they do not coordinate their vigilance to prevent its temporal overlapping. This finding does not support that foraging degus monitor the vigilance activity of group mates.
RENAL PREGLOMERULAR ARTERIAL–VENOUS O2 SHUNTING IS A STRUCTURAL ANTI‐OXIDANT DEFENCE MECHANISM OF THE RENAL CORTEX
Authors: O’Connor Paul M , Anderson Warwick P , Kett Michelle M , Evans Roger G
Published: June 2006

High blood flow to the kidney facilitates a high glomerular filtration rate, but total renal O2 delivery greatly exceeds renal metabolic requirements. However, tissue Po2 in much of the renal cortex is lower than may be expected, being similar to that of other organs in which perfusion is closely matched to metabolic demand.

The lower than expected renal cortical Po2 is now attributed largely to diffusional shunting of as much as 50% of inflowing O2 from blood within preglomerular arterial vessels to post‐glomerular venous vessels. However, the functional significance of this O2 shunting remains unclear. Indeed, this mechanism may appear maladaptive, given the kidney's susceptibility to hypoxic insults.

We hypothesize that renal preglomerular arterial–venous O2 shunting acts to protect the kidney from the potentially damaging consequences of tissue hyperoxia. The diffusion of O2 from arteries to veins within the kidney acts to reduce the O2 content of the blood before it is distributed to the renal microcirculation. Because high tissue Po2 may increase the production of reactive oxygen species, we suggest that renal arterial–venous O2 shunting may provide a physiological benefit to the organism by limiting O2 delivery to renal tissue, thereby reducing the risk of cellular oxidation.