bluuebunny/crossref_metadata_2025_split huggingface dataset:
Temperature‐independent diel variation in soil respiration observed from a temperate deciduous forest
Authors: LIU Q. , EDWARDS N. T. , POST W. M. , GU L. , LEDFORD J. , LENHART S. 
Published: September 2006

AbstractThe response of soil respiration (Rs) to temperature depends largely on the temporal and spatial scales of interest and how other environmental factors interact with this response. They are often represented by empirical exponential equations in many ecosystem analyses because of the difficulties in separating covarying environmental responses and in observing below ground processes. The objective of this study was to quantify a soil temperature‐independent component in Rs by examining the diel variation of an Rs time series measured in a temperate deciduous forest located at Oak Ridge, TN, USA between March and December 2003. By fitting 2 hourly, continuous automatic chamber measurements of CO2 efflux at the soil surface to a Q10 function to obtain the temperature‐dependent respiration (Rt) and plotting the diel cycles of Rt, Rs, and their difference (Ri), we found that an obvious temperature‐independent component exists in Rs during the growing season. The diel cycle of this component has a distinct day/night pattern and agrees well with diel variations in photosynthetically active radiation (PAR) and air temperature. Elevated canopy CO2 concentration resulted in similar patterns in the diel cycle of the temperature‐independent component but with different daily average rates in different stages of growing season. We speculate that photosynthesis of the stand is one of the main contributors to this temperature‐independent respiration component although more experiments are needed to draw a firm conclusion. We also found that despite its relatively small magnitude compared with the temperature‐dependent component, the diel variation in the temperature‐independent component can lead to significantly different estimates of the temperature sensitivity of soil respiration in the study forest. As a result, the common practice of using fitted temperature‐dependent function from night‐time measurements to extrapolate soil respiration during the daytime may underestimate daytime soil respiration.
Sea warming and fish distribution: the case of the small pelagic fish, Sardinella aurita, in the western Mediterranean
Authors: SABATÉS ANA , MARTÍN PALOMA , LLORET JOSEP , RAYA VANESA 
Published: September 2006

AbstractThis study analyses the temporal and spatial changes in abundance and distribution of the warm water species round sardinella (Sardinella aurita) in the western Mediterranean over the last decades in relation to sea water temperature. In the western Mediterranean basin (1950–2003), a significant positive relationship was found between round sardinella landings and temperature anomalies. Along a latitudinal gradient off the Mediterranean Iberian coast (1989–2004), a gradual increase in species abundance was observed from south to north, with a certain time lag going northwards, associated with the increase in sea water temperature. The abundance of round sardinella in the two warmest and southernmost areas was positively and significantly correlated with sea surface temperature registered during the start of gonad maturation the previous year. In addition, the positive relationship established between water temperature and abundance of round sardinella in the coldest and northernmost study area demonstrates that there is a temperature limit for the distribution of this species in the western Mediterranean. In addition, this study analyses round sardinella larvae distribution and abundance in the summers of 2003 and 2004, and conducts a comparison with the situation 20 years ago (summer 1983). Results show a marked increase in larval abundance during the last decades and the present appearance of larvae in the northernmost study areas, where they did not occur 20 years ago. This indicates the successful reproduction of round sardinella in the northern part of the Mediterranean, where the species has expanded, confirming its establishment in the area.
Effects of microflora on the neonatal development of gut mucosal T cells and myeloid cells in the mouse
Authors: Williams Amanda M. , Probert Christopher S. J. , Stepankova Renata , Tlaskalova‐Hogenova Helena , Phillips Anne , Bland Paul W. 
Published: September 2006

SummaryColonization with commensal flora in very early life may profoundly influence intestinal lymphoid development and bias later immune responses. We defined gut‐homing T cell phenotypes and the influence of flora on intestinal immune development in mice. Intestinal T cells were phenotyped and quantified in conventional (CV), germfree (GF) and conventionalized germfree (GF/CV) neonatal mice by immunohistochemistry. Mucosal adressin cell adhesion molecule 1 (MAdCAM‐1) was expressed by mucosal vessels at birth in CV and GF mice and was more prevalent in CV than GF small intestine, but was distributed similarly and did not change with age. Less MAdCAM‐1 was expressed in the colon; its distribution became restricted after weaning, with no difference between CV and GF mice. CD3+β7+ cells were present in similar numbers in CV and GF intestine at birth. They were CD62L– in CV mice and were accompanied by further CD3+β7+CD62L– T cells as development progressed, but in GF and GF/CV intestine they expressed CD62L and numbers did not change. IEL numbers increased at weaning in CV mice in both small and large intestine, but showed delayed development in GF intestine. Macrophages were present at high levels from birth in GF intestine, but dendritic cells did not develop until day 16. Thus, fetus‐derived T cells seed the intestinal lamina propria before birth via β–MadCAM interactions. Their activation status depends on the microbiological status of the dam, and without a commensal flora they remain naive. We propose that these cells regulate antigen responsiveness of the developing mucosal T cell pool.
Dendritic cells, but not macrophages or B cells, activate major histocompatibility complex class II‐restricted CD4+ T cells upon immune‐complex uptake in vivo
Authors: De Jong Judith M. H. , Schuurhuis Danita H. , Ioan‐Facsinay Andreea , Welling Mick M. , Camps Marcel G. M. , Van Der Voort Ellen I. H. , Huizinga Tom W. J. , Ossendorp Ferry , Verbeek J. Sjef , Toes René E. M. 
Published: September 2006

SummaryProfessional antigen‐presenting cells (APC) are able to process and present exogenous antigen leading to the activation of T cells. Antigen–immunoglobulin (Ig)G complexes (IC) are much more efficiently processed and presented than soluble antigen. Dendritic cells (DC) are known for their ability to take up and process immune complex (IC) via FcγR, and they have been shown to play a crucial role in IC‐processing onto major histocompatibility complex (MHC) class I as they contain a specialized cross‐presenting transport system required for MHC class I antigen‐processing. However, the MHC class II‐antigen‐processing pathway is distinct. Therefore various other professional APC, like macrophages and B cells, all displaying FcγR, are thought to present IC‐delivered antigen in MHC class II. Nonetheless, the relative contribution of these APC in IC‐facilitated antigen‐presentation for MHC class II in vivo is not known. Here we show that, in mice, both macrophages and DC, but not B cells, efficiently capture IC. However, only DC, but not macrophages, efficiently activate antigen‐specific MHC class II restricted CD4+ T cells. These results indicate that mainly DC and not other professional APC, despite expressing FcγR and MHC class II, contribute significantly to IC‐facilitated T cell activation in vivo under steady‐state conditions.
The strength of the chemotactic response to a CCR5 binding chemokine is determined by the level of cell surface CCR5 density
Authors: Desmetz Caroline , Lin Yea‐Lih , Mettling Clément , Portalès Pierre , Rabesandratana Herisoa , Clot Jacques , Corbeau Pierre 
Published: September 2006

SummaryWe have shown that the intensity of expression of the C‐C chemokine receptor CCR5 at the single CD4+ cell level strongly determines the efficiency of its function as a coreceptor for human immunodeficiency virus type 1. By analogy, we examined if the number of CCR5 molecules at the cell surface might determine its chemotactic response to CCR5 ligands. To test this hypothesis, we measured by flow cytometry the migration of primary human T cells towards the CCR5‐binding chemokine CCL5 in vitro. First, we observed a dose‐dependent blockage of this migration exerted by an anti‐CCR5 monoclonal antibody. Second, we sorted peripheral blood mononuclear cells into five subpopulations expressing various cell surface CCR5 densities, and observed a correlation between the intensity of migration towards CCL5 and the level of CCR5 expression on these subpopulations. Third, we transduced CCR5+ peripheral blood mononuclear cells with the CCR5 gene, and observed that the CCR5 over‐expression induced an over‐migration towards CCL5. Finally, we observed in healthy donors a correlation between the chemotactic response of peripheral blood CD8+ T cell to CCL5 and their level of surface CCR5 expression. T‐cell surface CCR5 density, which is constant over time for a given individual, but varies drastically among individuals, might therefore be an important personal determinant of T‐cell migration in many biological situations where CCR5‐binding chemokines play a role, such as graft rejection, T helper 1‐mediated auto‐immune diseases, and infectious diseases involving CCR5. Moreover, our data highlight the therapeutic potential of CCR5 antagonists in these situations.
The inflammation‐associated Salmonella SopA is a HECT‐like E3 ubiquitin ligase
Authors: Zhang Ying , Higashide Wendy M. , McCormick Beth A. , Chen Jue , Zhou Daoguo 
Published: September 2006

Summary Salmonella translocate a group of type III effectors into the host cells to induce entry, promote survival and cause intestinal inflammation. Although the biochemical and cellular mechanisms of how bacterial effectors function inside host cells remain largely unknown, studies have indicated that a likely strategy is to exploit host cellular pathways through functional mimicry. We report here that SopA, a Salmonella type III effector, mimics the mammalian HECT E3 ubiquitin ligase. SopA preferentially uses the host UbcH5a, UbcH5c and UbcH7 as E2s, which are involved in inflammation. Both the wild‐type SopA and the mutant SopAC753S were expressed and translocated at similar levels during the infection of HeLa cells. A Salmonella strain expressing a catalytically incompetent SopAC753S mutant had reduced Salmonella‐induced polymorphonuclear leukocytes transepithelial migration. We speculate that SopA ubiquitinate bacterial/host proteins involved in Salmonella‐induced intestinal inflammation.
Positive regulation of Bacillus subtilis ackA by CodY and CcpA: establishing a potential hierarchy in carbon flow
Authors: Shivers Robert P. , Dineen Sean S. , Sonenshein Abraham L. 
Published: September 2006

SummaryConversion of pyruvate to acetate via the phosphotransacetylase‐acetate kinase pathway generates ATP and is a major overflow pathway under conditions of carbon and nitrogen excess. In Bacillus subtilis, this pathway is positively regulated by CcpA, a global regulator of carbon metabolism genes. Transcription of the acetate kinase gene (ackA) proved to be activated as well by a second global regulatory protein, CodY. Expression of an ackA–lacZ fusion was reduced in a codY mutant strain. CodY was found to bind in vitro to two sites in the ackA promoter region and to stimulate ackA transcription in a run‐off transcription assay. This is the first known case of direct positive regulation by CodY. CodY and CcpA were found to bind to neighbouring sites and their effects were additive both in vivo and in vitro. Surprisingly, positive regulation by CodY, unlike repression, responded primarily to only one type of effector molecule. That is, branched‐chain amino acids (BCAAs) served as more potent co‐activators of CodY‐dependent ackA transcription than did GTP. Given the roles of CcpA and CodY in regulating genes whose products determine the metabolic fate of pyruvate, these two proteins may act together to mediate a hierarchical conversion of pyruvate to its many potential products.
Differentiation between electron transport sensing and proton motive force sensing by the Aer and Tsr receptors for aerotaxis
Authors: Edwards Jessica C. , Johnson Mark S. , Taylor Barry L. 
Published: September 2006

SummaryAerotaxis (oxygen‐seeking) behaviour in Escherichia coli is a response to changes in the electron transport system and not oxygen per se. Because changes in proton motive force (PMF) are coupled to respiratory electron transport, it is difficult to differentiate between PMF, electron transport or redox, all primary candidates for the signal sensed by the aerotaxis receptors, Aer and Tsr. We constructed electron transport mutants that produced different respiratory H+/e– stoichiometries. These strains expressed binary combinations of one NADH dehydrogenase and one quinol oxidase. We then introduced either an aer or tsr mutation into each mutant to create two sets of electron transport mutants. In vivo H+/e– ratios for strains grown in glycerol medium ranged from 1.46 ± 0.18–3.04 ± 0.47, but rates of respiration and growth were similar. The PMF jump in response to oxygen was proportional to the H+/e– ratio in each set of mutants (r2 = 0.986–0.996). The length of Tsr‐mediated aerotaxis responses increased with the PMF jump (r2 = 0.988), but Aer‐mediated responses did not correlate with either PMF changes (r2 = 0.297) or the rate of electron transport (r2 = 0.066). Aer‐mediated responses were linked to NADH dehydrogenase I, although there was no absolute requirement. The data indicate that Tsr responds to changes in PMF, but strong Aer responses to oxygen are associated with redox changes in NADH dehydrogenase I.
Transcriptional regulation of the Pseudomonas aeruginosa type III secretion system
Authors: Yahr Timothy L. , Wolfgang Matthew C. 
Published: September 2006

SummaryType III secretion systems (T3SS) function by translocating effector proteins into eukaryotic host cells and are important for the virulence of many Gram‐negative bacterial pathogens. Although the secretion and translocation machineries are highly conserved between different species, each pathogen translocates a unique set of effectors that subvert normal host cell physiology to promote pathogenesis. The uniqueness of each pathogen is further reflected in the diversity of mechanisms used to regulate T3SS gene expression. Pseudomonas aeruginosa utilizes a complex set of signalling pathways to modulate T3SS expression in response to extracellular and intracellular cues. Whereas some pathways are dedicated solely to regulating the T3SS, others co‐ordinately regulate expression of the T3SS with multiple virulence functions on a global scale. Emerging regulatory themes include coupling of T3SS transcription with type III secretory activity, global regulatory control through modulation of cAMP biosynthesis, repression by a variety of stresses, involvement of multiple two component regulatory systems, and an inverse relationship between T3SS expression and multicellular behaviour. Factors controlling activation of T3SS expression likely contribute to the environmental survival of the organism and to the pathogenesis of acute P. aeruginosa infections. Conversely, active repression of the T3SS might contribute to the persistence of chronic infections.
Impact of a communication programme on female genital cutting in eastern Nigeria
Authors: Babalola Stella , Brasington Angela , Agbasimalo Ada , Helland Anna , Nwanguma Edith , Onah Nkechi 
Published: September 2006

SummaryObjectives  This study describes a female genital cutting (FGC) elimination communication programme in Enugu State and assesses its impact in changing relevant knowledge, attitudes and behavioural intentions.Methods  The FGC programme combined a community mobilization component with targeted advocacy and mass media activities. Data for assessing the impact of the programme derived from baseline and follow‐up surveys in three intervention local government areas (LGA) in Enugu State and three comparison LGAs in Ebonyi State. An ideation model of behaviour change guided the analyses of the impact of the programme on personal advocacy for FGC, perceived self‐efficacy to refuse pressure to perform FGC, perceived social support for FGC discontinuation, perceived benefits of FGC, perceived health complications of FGC and intention not to perform FGC on daughters. The analytical methods include comparing change in pertinent outcome variables from baseline to follow‐up in the two study states and using logistic regression on follow‐up data for the intervention state to assess the link between programme exposure and the relevant outcome indicators.Results  The data show that while the pertinent ideational factors and the intention not to perform FGC either worsened or remained stagnant in Ebonyi State, they improved significantly in Enugu State. The logistic regression results show that programme exposure is associated with the expected improvements in all the pertinent indicators.Conclusion  The multimedia communication programme has been effective in changing FGC‐related attitudes and promoting the intention not to perform FGC.
A double‐blind randomized controlled trial of antenatal mebendazole to reduce low birthweight in a hookworm‐endemic area of Peru
Authors: Larocque Renée , Casapia Martin , Gotuzzo Eduardo , MacLean J. Dick , Soto Julio C. , Rahme Elham , Gyorkos Theresa W. 
Published: September 2006

SummaryObjective  To assess the effect on birthweight of antenatal mebendazole plus iron vs. placebo plus iron in a highly hookworm‐endemic area.Methods  Double‐blind, randomized controlled trial set in rural and peri‐urban communities in the Peruvian Amazon region. A total of 1042 second trimester pregnant women between the ages of 18 and 44 years were recruited from April to November 2003, and followed to July 2004. Women were randomly assigned to receive either mebendazole (500 mg single dose) plus iron supplements (60 mg elemental iron daily) or placebo plus iron supplements. The primary outcome was mean infant birthweight and secondary measures included proportion of low birthweight babies and maternal anaemia.Results  The prevalence of hookworm infection was 47.5%. There were no differences between intervention groups in mean birthweight (3104 g vs. 3090 g, P = 0.629), proportion of low birthweight (<2500 g; 8.1%vs. 8.7%, P = 0.755) or maternal anaemia in the third trimester [33.0% (158/479) vs. 32.3% (152/471), P = 0.815]. However, the proportion of very low birthweight (<1500 g) was significantly lower in the mebendazole group [0% (0/479) vs. 1.5% (7/471), P = 0.007].Conclusions  This trial provides additional evidence for the use of anthelmintics, over and above iron supplementation, within antenatal care programmes in hookworm‐endemic areas. Benefits of de‐worming may be higher in countries not having an antenatal iron supplementation programme or where intensity of hookworm infections is higher.Keywords mebendazole , pregnant women , hookworm , birthweight , anaemia , randomized‐controlled trial
Artesunate + amodiaquine and artesunate + sulphadoxine–pyrimethamine for treatment of uncomplicated malaria in Democratic Republic of Congo: a clinical trial with determination of sulphadoxine and pyrimethamine‐resistant haplotypes
Authors: Swarthout T. D. , Van Den Broek I. V. , Kayembe G. , Montgomery J. , Pota H. , Roper C. 
Published: September 2006

SummaryWe undertook a trial of artesunate + amodiaquine (AS + AQ) and artesunate + sulphadoxine–pyrimethamine (AS + SP) in 180 children of age 6–59 months with uncomplicated malaria in Democratic Republic of Congo. Children were randomly allocated to receive 3 days observed treatment of AS + AQ (n = 90) or 3 days of AS + SP (n = 90). Primary efficacy outcomes were 28‐day parasite recurrence rates, and recrudescence rates were adjusted by genotyping to distinguish new infection and recrudescence. In addition, we determined the prevalence of molecular markers of resistance to sulphadoxine and pyrimethamine. Day 28 parasite recurrence rates were 16.9% (14/83; 95% CI: 9.5–26.7) in the AS + AQ group and 34.6% (28/81; 95% CI: 24.3–46.0) in the AS + SP group (P = 0.009). After PCR correction, recrudescence rates were 6.7% (5/74; 95% CI: 2.2–15.1) for AS + AQ and 19.7% (13/66; 95% CI: 10.9–31.3) for AS + SP (P = 0.02). There was no significant difference between the two arms in time to parasite clearance, fever clearance and gametocyte clearance. Parasite genotyping showed high frequencies of dihydrofolate reductase (dhfr) and dihydropteroate synthase (dhps) molecular SP‐resistance markers, with 57% of the samples showing more than three mutations linked to SP resistance, and 27% with triple‐dhfr/double‐dhps haplotype, confirming that SP treatment failure rates are likely to be high. AS + AQ had significantly higher efficacy than AS + SP. These results contributed to the subsequent change to AS + AQ as first‐line regimen in the country. Efforts to properly implement the new protocol and maintain adherence at acceptable levels should include health staff and patient sensitization. The 6.8% recrudescence rate indicates that AS + AQ should be monitored closely until a more effective artemisinin combination therapy regimen is needed and can be introduced.
Carbohydrate Profiles During Cotton Floral Bud (Square) Development
Authors: Tarpley L. , Sassenrath G. F. 
Published: September 2006

AbstractCotton (Gossypium hirsutum) flower's showy corolla expands rapidly, then senesces quickly. Efficient opening of corollas is important for self‐ and cross‐pollination, and indirectly lint yield. Carbohydrate relations are integral to bud water relations and growth, although they are not well understood. Soluble sugars and starch in developing floral buds and flowers of field‐grown cotton plants were analysed. Buds contained significantly more sugar than starch. Sucrose and its hydrolysis products strongly contributed to increased sugars during corolla expansion, and contributed −0.211 MPa to osmotic potential. Water concentration was constant throughout expansion at 860 g kg−1 FW, suggesting sucrose import and hydrolysis are coordinated with other drivers of expansion. Floral sugar content declined sharply during senescence (69 % in 24 h). Although remobilization to other organs could partially explain this decline, we suggest the possibility that most sugar is broken down via respiration, resulting in the production of metabolic water and the significant 7 % increase in floral water concentration during senescence. In summary, imported sucrose and its hydrolysis products increased rapidly during cotton floral bud growth, and supported bud expansion by decreasing the water potential of bud tissue.