bluuebunny/crossref_metadata_2025_split huggingface dataset:
An atypical receiver domain controls the dynamic polar localization of the Myxococcus xanthus social motility protein FrzS
Authors: Fraser James S. , Merlie John P. , Echols Nathaniel , Weisfield Shellie R. , Mignot Tâm , Wemmer David E. , Zusman David R. , Alber Tom 
Published: June 2007

SummaryThe Myxococcus xanthus FrzS protein transits from pole‐to‐pole within the cell, accumulating at the pole that defines the direction of movement in social (S) motility. Here we show using atomic‐resolution crystallography and NMR that the FrzS receiver domain (RD) displays the conserved switch Tyr102 in an unusual conformation, lacks the conserved Asp phosphorylation site, and fails to bind Mg2+ or the phosphoryl analogue, Mg2+·BeF3. Mutation of Asp55, closest to the canonical site of RD phosphorylation, showed no motility phenotype in vivo, demonstrating that phosphorylation at this site is not necessary for domain function. In contrast, the Tyr102Ala and His92Phe substitutions on the canonical output face of the FrzS RD abolished S‐motility in vivo. Single‐cell fluorescence microscopy measurements revealed a striking mislocalization of these mutant FrzS proteins to the trailing cell pole in vivo. The crystal structures of the mutants suggested that the observed conformation of Tyr102 in the wild‐type FrzS RD is not sufficient for function. These results support the model that FrzS contains a novel ‘pseudo‐receiver domain’ whose function requires recognition of the RD output face but not Asp phosphorylation.
Non-adiabatic oscillations of red giants
Authors: Xiong D. R. , Deng L. 
Published: June 2007

Abstract
Using our non-local time-dependent theory of convection, the linear non-adiabatic oscillations of 10 evolutionary model series with masses of 1–3 M⊙ are calculated. The results show that there is a red giant instability strip in the lower temperature side of the Hertzsprung–Russell diagram which goes along the sequences of the red giant branch and the asymptotic giant branch. For red giants of lower luminosities, pulsation instability is found at high order overtones; the lower order modes from the fundamental to the second overtone are stable. Towards higher luminosity and lower effective temperature, instability moves to lower order modes, and the amplitude growth rate of oscillations also grows. At the high luminosity end of the strip, the fundamental and the first overtone become unstable, while all the modes above the fourth order become stable. The excitation mechanisms have been studied in detail. It is found that turbulent pressure plays a key role for excitation of red variables. The frozen convection approximation is unavailable for the low temperature stars with extended convective envelopes. In any case, this approximation can explain neither the red edge of the Cepheid instability strip, nor the blue edge of the pulsating red giant instability strip. An analytic expression of a pulsation constant as a function of stellar mass, luminosity and effective temperature is presented from this work.
A large-scale extinction map of the Galactic Anticentre from 2MASS
Authors: Froebrich D. , Murphy G. C. , Smith M. D. , Walsh J. , Del Burgo C. 
Published: June 2007

Abstract
We present a 127 × 63-deg2 extinction map of the Anticentre of the Galaxy, based on 〈J−H〉 and 〈H−K〉 colour excess maps from the Two-Micron All-Sky Survey. This 8001-deg2 map with a resolution of 4 arcmin is provided as online material. The colour excess ratio 〈J−H〉/〈H−K〉 is used to determine the power-law index of the reddening law (β) for individual regions contained in the area (e.g. Orion, Perseus, Taurus, Auriga, Monoceros, Camelopardalis, Cassiopeia). On average we find a dominant value of β= 1.8 ± 0.2 for the individual clouds, in agreement with the canonical value for the interstellar medium. We also show that there is an internal scatter of β values in these regions, and that in some areas more than one dominant β values are present. This indicates large-scale variations in the dust properties. The analysis of the AV values within individual regions shows a change in the slope of the column density distribution with distance. This can be attributed either to a change in the governing physical processes in molecular clouds on spatial scales of about 1 pc or to an AV dilution with distance in our map.
Spatially resolved kinematics and stellar populations of brightest cluster and group galaxies
Authors: Brough S. , Proctor Robert , Forbes Duncan A. , Couch Warrick J. , Collins C. A. , Burke D. J. , Mann R. G. 
Published: June 2007

AbstractWe present an examination of the kinematics and stellar populations of a sample of three brightest group galaxies (BGGs) and three brightest cluster galaxies (BCGs) in X-ray groups and clusters. We have obtained high signal-to-noise ratio Gemini/Gemini South Multi-Object Spectrograph (GMOS) long-slit spectra of these galaxies and use Lick indices to determine ages, metallicities and α-element abundance ratios out to at least their effective radii. We find that the BGGs and BCGs have very uniform masses, central ages and central metallicities. Examining the radial dependence of their stellar populations, we find no significant velocity dispersion, age, or α-enhancement gradients. However, we find a wide range of metallicity gradients, suggesting a variety of formation mechanisms. The range of metallicity gradients observed is surprising, given the homogeneous environment these galaxies probe and their uniform central stellar populations. However, our results are inconsistent with any single model of galaxy formation and emphasize the need for more theoretical understanding of both the origins of metallicity gradients and galaxy formation itself. We postulate two possible physical causes for the different formation mechanisms.
Research on recurrent pregnancy complications: a clinician's perspective
Authors: Smulian John C. 
Published: June 2007

SummaryResearch on recurrent pregnancy complications is essential to help clinicians provide appropriate counselling and guide the management of patients with a history of adverse pregnancy outcomes. However, recurrence research is complex, in both its execution and interpretation. The paucity of appropriate data sets accessible for study of recurrent pregnancy outcomes presents significant challenges in performing recurrence research. This is further compounded by the different perspectives on recurrence between epidemiologists and clinicians. The interpretation of risk, whether it is absolute risk, relative risk or population‐attributable fraction, underlies the often opposing perspectives of researchers and clinicians. Because clinicians acutely feel the need to provide appropriate counselling and management strategies when there has been a previous pregnancy complication, it is necessary that all those involved in research and care for these women work together to address gaps in our knowledge for recurrent pregnancy outcomes. In this way, we can develop a better understanding of disease processes, counsel patients better, design management plans and, ultimately, achieve better outcomes for our patients.
Stillbirth recurrence in a population of relatively low‐risk mothers
Authors: Sharma Puza P. , Salihu Hamisu M. , Kirby Russel S. 
Published: June 2007

SummaryWe sought to estimate the risk of stillbirth recurrence among relatively low‐risk women, a group defined as maternal age <35 years; absence of congenital anomalies; gestational age range of 20–44 weeks inclusive; singleton births; and non‐smokers. The Missouri maternally linked data containing births from 1978 to 1997 were used for the study. We identified the study group (low‐risk gravidae who experienced a stillbirth in the first pregnancy) and a comparison group (low‐risk gravidae who delivered a live birth in their first pregnancy) and compared the stillbirth risks in the second pregnancy between both groups. Analysis was based on 261 384 women with information on first and second pregnancies [1050 (0.5%) women with stillbirth].Of the 947 cases of stillbirth in the second pregnancy, 20 cases occurred in women with a history of stillbirth (stillbirth rate 19.0 per 1000 births) and 927 in the comparison group (stillbirth rate 3.6 per 1000 births; P < 0.001). The adjusted risk of stillbirth was almost six times higher in women with a prior stillbirth (hazard ratio [HR] 5.8, [95% CI 3.7, 9.0]). Analysis by stillbirth subtype in the second pregnancy showed that history of stillbirth conferred greater risk for subsequent early (fetal deaths between 20 and 28 weeks) (HR 10.3, [95% CI 6.1, 17.2]) than late stillbirths (fetal deaths at ≥29 weeks) (HR 2.5, [95% CI 1.0, 6.0]); and for intrapartum (HR 12.2, [95% CI 4.5, 33.3]) than antepartum (HR 4.2, [95% CI 2.3, 7.7]) stillbirths. Among relatively low‐risk women, history of stillbirth was associated with increased recurrence, with substantial heterogeneity by timing of stillbirth.
The effects and mechanisms of primiparity on the risk of pre‐eclampsia: a systematic review
Authors: Luo Zhong‐Cheng , An Na , Xu Hai‐Rong , Larante Amelie , Audibert Francois , Fraser William D. 
Published: June 2007

SummaryPre‐eclampsia has been dubbed as ‘a disease of primiparity’. However, the effects and mechanisms of the association of primiparity with pre‐eclampsia have not been clearly defined. We conducted a systematic review of studies evaluating the effect of primiparity on the risk of pre‐eclampsia, and studies (published between January 1966 and July 2005) on the mechanisms underlying such an association. A total of 26 original studies were identified and a meta‐analysis carried out for the risk of pre‐eclampsia among primiparous vs. multiparous women.Variably (1.4–5.5 times) higher risks of pre‐eclampsia were observed in primiparous women in all studies, with a summary odds ratio (OR) of 2.42 [95% CI 2.16, 2.71]. The adjusted ORs were larger than crude ORs in all but one study after various adjustments. Except for abundant epidemiological evidence in support of the immune maladaptation theory, only four original studies examined the actual mechanisms of such primiparity‐associated risk. Two (small) studies suggested differences in immunological responses in the aetiology of pre‐eclampsia in primiparous vs. multiparous women. Two recent studies indicated that differences in angiogenic factor profile or reactivity to insulin resistance in early pregnancy may explain the elevated pre‐eclampsia risk in first pregnancies. In conclusion, primiparity is associated with approximately 2.4‐fold elevated risk of pre‐eclampsia. Although immune maladaptation is generally considered as the basis to explain such an elevated risk, few data are available on immune maladaptation parameters in primiparous vs. multiparous pregnancies. Available data are insufficient to interpret the mechanisms of such primiparity‐associated excess risk of pre‐eclampsia.
Cysteine proteinase 30 (CP30) and antibody response to CP30 in serum and vaginal washes of symptomatic and asymptomatic Trichomonas vaginalis‐infected women
Authors: YADAV M. , DUBEY M. L. , GUPTA I. , MALLA N. 
Published: June 2007

SUMMARY Infection with Trichomonas vaginalis may be asymptomatic or with symptoms suggestive of vaginitis. Because cysteine proteinase 30 (CP30) of T. vaginalis is known to be a virulence marker that plays a role in cytoadherence, the aim of this study was to analyse the presence of CP30 and antibody to CP30 in clinical samples of symptomatic and asymptomatic infected women. CP30 was detected in all the serum and vaginal washes (VWs) of symptomatic women and in 65% of the serum and 80% of the VWs of asymptomatic women. This suggested that the majority of asymptomatic women also exhibit CP30 in the serum and VWs. Antibody to CP30 was detected in all the serum samples of symptomatic and asymptomatic women and in the VWs of only 54·5% of the symptomatic and 35% of the asymptomatic women. Antibody to CP30 was also detected in 3/20 of the serum samples and in none of the VWs from uninfected women. Significantly higher amounts of antibody (mean OD values) were observed in serum and VWs of symptomatic as compared to asymptomatic and healthy women (P < 0·001). These results indicate that besides CP30, other factors may also be playing a role in leading to symptomatic infection, because CP30 was detected in clinical samples from all the symptomatic and the majority of the asymptomatic women. Although anti‐CP30 antibodies do not appear to be protective, detection of antibody to CP30 antigen in serum samples may be used as a diagnostic tool.
Determining the limitations and regulation of photosynthetic energy transduction in leaves
Authors: BAKER NEIL R. , HARBINSON JEREMY , KRAMER DAVID M. 
Published: June 2007

ABSTRACTThe light‐dependent production of ATP and reductants by the photosynthetic apparatusin vivoinvolves a series of electron and proton transfers. Consideration is given as to how electron fluxes through photosystem I (PSI), using absorption spectroscopy, and through photosystem II (PSII), using chlorophyll fluorescence analyses, can be estimatedin vivo. Measurements of light‐induced electrochromic shifts using absorption spectroscopy provide a means of analyzing the proton fluxes across the thylakoid membranesin vivo. Regulation of these electron and proton fluxes is required for the thylakoids to meet the fluctuating metabolic demands of the cell. Chloroplasts exhibit a wide and flexible range of mechanisms to regulate electron and proton fluxes that enable chloroplasts to match light use for ATP and reductant production with the prevailing metabolic requirements. Non‐invasive probing of electron fluxes through PSI and PSII, and proton fluxes across the thylakoid membranes can provide insights into the operation of such regulatory processesin vivo.
Photosynthesis and resource distribution through plant canopies
Authors: NIINEMETS ÜLO 
Published: June 2007

ABSTRACTPlant canopies are characterized by dramatic gradients of light between canopy top and bottom, and interactions between light, temperature and water vapour deficits. This review summarizes current knowledge of potentials and limitations of acclimation of foliage photosynthetic capacity (Amax) and light‐harvesting efficiency to complex environmental gradients within the canopies. Acclimation of Amax to high light availability involves accumulation of rate‐limiting photosynthetic proteins per unit leaf area as the result of increases in leaf thickness in broad‐leaved species and volume : total area ratio and mesophyll thickness in species with complex geometry of leaf cross‐section. Enhancement of light‐harvesting efficiency in low light occurs through increased chlorophyll production per unit dry mass, greater leaf area per unit dry mass investment in leaves and shoot architectural modifications that improve leaf exposure and reduce within‐shoot shading. All these acclimation responses vary among species, resulting in species‐specific use efficiencies of low and high light. In fast‐growing canopies and in evergreen species, where foliage developed and acclimated to a certain light environment becomes shaded by newly developing foliage, leaf senescence, age‐dependent changes in cell wall characteristics and limited foliage re‐acclimation capacity can constrain adjustment of older leaves to modified light availabilities. The review further demonstrates that leaves in different canopy positions respond differently to dynamic fluctuations in light availability and to multiple environmental stresses. Foliage acclimated to high irradiance respond more plastically to rapid changes in leaf light environment, and is more resistant to co‐occurring heat and water stress. However, in higher light, co‐occurring stresses can more strongly curb the efficiency of foliage photosynthetic machinery through reductions in internal diffusion conductance to CO2. This review demonstrates strong foliage potential for acclimation to within‐canopy environmental gradients, but also highlights complex constraints on acclimation and foliage functioning resulting from light × foliage age interactions, multiple environmental stresses, dynamic light fluctuations and species‐specific leaf and shoot structural constraints.
Effects of inoculum potential, shading and soil temperature on root infection of oil palm seedlings by the basal stem rot pathogen Ganoderma boninense
Authors: Rees R. W. , Flood J. , Hasan Y. , Cooper R. M. 
Published: June 2007

Ganoderma boninense causes severe losses to oil palm in South East Asia. The disease typically manifests itself as basal stem rot, but there remains controversy over the route of infection and source of inoculum. Using isolates differing in aggressiveness, infection via roots was confirmed; it was also shown that large inoculum provided as Ganoderma‐infested palm‐ or rubber‐wood blocks (12 × 6 × 6 cm) is necessary for soil infection of seedlings after 6–8 months. Smaller blocks (3 × 3 × 3 cm) produced rapid (≤ 3 months) infection of roots and lower stem when physically attached to roots. Therefore fragmentation of infested palm wood from a felled, mature plantation before subsequent replanting may provide inoculum. Failure of G. boninense to grow through non‐sterile soil or organic debris from frond bases, suggests it is a poor competitor and that roots must contact inoculum directly. Severe disease occurred after 8 months on inoculated seedlings under shade, but not on seedlings exposed to sun. Soil temperatures in sunlight frequently rose above 40°C and reached 45°C, whereas in shade they never exceeded 32°C. Ganoderma boninense is probably inhibited in exposed soil since optimal growth in vitro was 25–30°C, and there was no recovery from 45°C. Soil temperature may explain why symptoms often first appear in mature plantations when canopy formation creates shade. Infection is not peculiar to senescing palms but can occur throughout the growth cycle.
Sensitivity of Phytophthora infestans to mandipropamid and the effect of enforced selection pressure in the field
Authors: Cohen Y. , Rubin E. , Hadad T. , Gotlieb D. , Sierotzki H. , Gisi U. 
Published: June 2007

Sensitivity to the new carboxylic acid amide (CAA) fungicide mandipropamid (MPD) in Phytophthora infestans was measured for isolates collected between 1989 and 2002 in Israel prior to the commercial use of MPD (baseline sensitivity, 44 isolates), and from MPD‐treated (25 isolates) and untreated fields (215 isolates) in nine European countries and Israel between 2001 and 2005. All isolates were sensitive to MPD, with EC50 values ranging between 0·02 and 2·98 µg mL−1. Plastic‐tunnel (UK), shade‐house (Israel) and field experiments (Israel) conducted during 2001–05 showed that enforced selection pressure, applied preventively or curatively, imposed by repeated sublethal (5 µg mL−1) or excessive (500–1000 µg mL−1) doses of MPD on mixed isolates of P. infestans produced no isolates resistant to the compound. The results of this study indicate that the probability of a buildup of resistant sub‐populations of P. infestans to mandipropamid in the field is low.
Widespread transport of pyroclastic density currents from a large silicic tuff ring: the Glaramara tuff, Scafell caldera, English Lake District, UK
Authors: BROWN R. J. , KOKELAAR B. P. , BRANNEY M. J. 
Published: June 2007

AbstractThe Glaramara tuff presents extensive exposures of the medial and distal deposits of a large tuff ring (original area >800 km2) that grew within an alluvial to lacustrine caldera basin. Detailed analysis and correlation of 21 sections through the tuff show that the eruption involved phreatomagmatic to magmatic explosions resulting from the interaction of dacitic magma and shallow‐aquifer water. As the eruption developed to peak intensity, numerous, powerful single‐surge pyroclastic density currents reached beyond 8 km from the vent, probably >12 km. The currents were strongly depletive and deposited coarse lapilli (>5 cm in diameter) up to 5 km from source, with only fine ash and accretionary lapilli deposited beyond this. As the eruption intensity waned, currents deposited fine ash and accretionary lapilli across both distal and medial regions. The simple wax–wane cycle of the eruption produced an overall upward coarsening to fining sequence of the vertical lithofacies succession together with a corresponding progradational to retrogradational succession of lithofacies relative to the vent. Various downcurrent facies transitions record transformations of the depositional flow‐boundary zones as the depletive currents evolved with distance, in some cases transforming from granular fluid‐based to fully dilute currents primarily as a result of loss of granular fluid by deposition. The tuff‐ring deposits share several characteristics with (larger) ignimbrite sheets formed during Plinian eruptions and this underscores some overall similarities between pyroclastic density currents that form tuff rings and those that deposit large‐volume ignimbrites. Tuff‐ring explosive activity with such a wide area of impact is not commonly recognized, but it records the possibility of such currents and this should be factored into hazard assessments.
Lake sediments deposited on the Flims rockslide mass: the key to date the largest mass movement of the Alps
Authors: Deplazes Gaudenz , Anselmetti Flavio S. , Hajdas Irka 
Published: June 2007

AbstractLong piston cores taken from the subsurface of two mountain lakes of the eastern Swiss Alps recovered sediments, which overlie the Flims rockslide deposits. These sediments provide new information on the chronology of the largest known Alpine rockslide and can be used to reconstruct the post landslide environmental evolution. The oldest 14C date of the lake sediments yields a minimum age of the rockslide at 9660–9430 cal. yr BP. In addition, the dating of a wood fragment contained in the rockslide deposits directly below the lake sediments shows a maximum age of 9480–9120 cal. yr BP. The overlap of the maximum and minimum ages, 9480–9430 cal. yr BP, approximates the age of the Flims rockslide. This early Holocene range coincides with a period of higher frequency of large mass movements observed in the Alps, which could be related to climatic changes.
Illegitimate recombination is a major evolutionary mechanism for initiating size variation in plant resistance genes
Authors: Wicker Thomas , Yahiaoui Nabila , Keller Beat 
Published: June 2007

SummaryCurrent models for the evolution of plant disease resistance (R) genes are based on mechanisms such as unequal crossing‐over, gene conversion and point mutations as sources for genetic variability and the generation of new specificities. Size variation in leucine‐rich repeat (LRR) domains was previously mainly attributed to unequal crossing‐over or template slippage between LRR units. Our analysis of 112 R genes and R gene analogs (RGAs) from 16 different gene lineages from monocots and dicots showed that individual LRR units are mostly too divergent to allow unequal crossing‐over. We found that illegitimate recombination (IR) is the major mechanism that generates quasi‐random duplications within the LRR domain. These initial duplications are required as seeds for subsequent unequal crossing‐over events which cause the observed rapid increase or decrease in LRR repeat numbers. Ten of the 16 gene lineages studied contained such duplications, and in four of them the duplications served as a template for subsequent repeat amplification. Our analysis of Pm3‐like genes from rice and three wheat species showed that such events can be traced back more than 50 million years. Thus, IR represents a major new evolutionary mechanism that is essential for the generation of molecular diversity in evolution of RGAs.