bluuebunny/crossref_metadata_2025 huggingface dataset:
The Influence of Temporal Distance on Consumer Preferences for Technology‐Based Innovations*
Authors: Ziamou Paschalina (Lilia) , Veryzer Robert W.
Published: June 2005

Rapid technological developments in the computer and the telecommunications industries have spurred the introduction of technology‐based products. An important feature of these products is that they can be characterized based on improvements in the functionality and the interface. When consumers evaluate a technology‐based product, they face a trade‐off: How should they choose between a product that offers a superior functionality and another product that offers a superior interface? The present research focuses on how temporal distance (i.e., time) from the purchase or use occasion of a technology‐based innovation influences consumers' evaluations of the new product. Specifically, the present study examines how temporal distance affects the trade‐offs consumers make between improvements in the interface and improvements in the functionality of a new product. This research demonstrates that the weight consumers place on the functionality and the interface of a new product is a function of the temporal distance. Specifically, the functionality of the product is valued more in distant future events. In contrast, the interface of the product is more important in the near future. This research has direct implications for various aspects of the new product development process such as customer‐product research methods used, communication strategies, and product preannouncements.
User Toolkits for Innovation: Consumers Support Each Other
Authors: Jeppesen Lars Bo
Published: June 2005

User toolkits for innovation were recently proposed as a means to eliminate (costly) exchange of need‐related information between users and manufactures in the product development process. The method transfers certain development tasks to users and thereby empowers them to create their own desired product features. This article examines the implications of different levels of opportunities for consumer involvement (OCI) in product development to learn what happens when firms pass design tasks on to consumers. It explores this issue by studying the relation between the employment of user toolkits and the need for firms to support their consumers. An analysis of 78 computer games products and the amount of support given by firms to the consumers of these products suggests that a share of the costs firms save on information acquisition by letting consumers “do it themselves” may eventually reemerge as costs in consumer support. In other words, an increase in opportunities for consumer involvement seems to increase the need for supporting consumers. A promising solution to the problem of support costs is identified, namely, the establishment of consumer–consumer support interaction. A case study of an outlier in terms of firm support to consumers—Westwood Studios—shows that consumers who use toolkits may be willing to support each other. Such interactive problem solving in a firm‐established user community is advantageous to the firm, because the process reduces the amount of resources that the firm itself needs to dedicate to the support of consumers using toolkits. Generally, consumer‐to‐consumer interaction can facilitate problem‐solving in the consumer domain, can aid the diffusion of toolkit related knowledge, and potentially can enhance the outcomes produced by the toolkit approach.
Acute and chronic pain following craniotomy: a review
Authors: De Gray L. C. , Matta B. F.
Published: June 2005

Postoperative pain is an important clinical problem that has received increasing attention in recent years. However, pain following craniotomy has been a comparatively neglected topic; this review seeks to redress this imbalance. A brief overview of the anatomy of the skull and its linings is given, with particular reference to innervation. The various approaches for craniotomies are classified, with their association with acute and long‐term effects on analgesic requirements. A comprehensive search of the literature was undertaken to ascertain the incidence of acute pain post craniotomy and current thoughts on pharmacological management, touching briefly on pre‐emptive treatment. Also discussed is the much neglected but nevertheless real incidence of chronic pain following craniotomy and its underlying pathogenesis, prevention and treatment.
Anabolic steroid abuse: physiological and anaesthetic considerations
Authors: Kam P. C. A. , Yarrow M.
Published: June 2005

This review summarises the physiological and pharmacological effects of the anabolic steroids used to enhance performance in sports. The anabolic steroids promote muscle growth and protein synthesis. Side‐effects of anabolic steroids include cardiomyopathy, atherosclerosis, hypercoagulopathy, hepatic dysfunction, and psychiatric and behavioural disturbances. It is therefore appropriate that the anaesthetist be familiar with the abuse of anabolic steroids, their potential adverse effects, and the peri‐operative risk associated with the use of these drugs.
Anaesthesia for Caesarean section and neonatal acid‐base status: a meta‐analysis*
Authors: Reynolds F. , Seed P. T.
Published: June 2005

Spinal anaesthesia is generally preferred for Caesarean section. Its superiority for the baby is often assumed. Umbilical artery acid‐base status provides a valid index of fetal welfare. Twenty‐seven studies reporting neonatal acid‐base data with different types of anaesthesia were used to compare umbilical artery or vein pH and base deficit, using random‐effect meta‐analysis. Cord pH was significantly lower with spinal than with both general (difference: −0.015; 95% CI −0.029 to −0.001; 13 studies, 1272 subjects) and epidural anaesthesia (difference −0.013; 95% CI −0.024 to −0.002; 11 studies, 828 subjects). Larger doses of ephedrine contributed to the latter effect (p = 0.023). Sixteen studies reported a base deficit, which was significantly higher for spinal than for general (difference 1.109; 95% CI 0.434–1.784 mEq.l−1; seven studies, 695 subject) and epidural anaesthesia (difference 0.910; 95% CI 0.222–1.598 mEq.l−1; seven studies, 497 subjects). Spinal anaesthesia cannot be considered safer than epidural or general anaesthesia for the fetus.
Movement of the upper cervical spine during laryngoscopy: a comparison of the Bonfils intubation fibrescope and the Macintosh laryngoscope
Authors: Rudolph C. , Schneider J. P. , Wallenborn J. , Schaffranietz L.
Published: June 2005

The movements of the upper cervical spine were measured by fluoroscopy in 20 patients during laryngoscopy with the Bonfils intubation fibrescope and the Macintosh laryngoscope. Laryngoscopy with both the Bonfils intubation fibrescope and the Macintosh laryngoscope resulted in significant extension of the cervical spine as compared to the neutral position but this extension was significantly less with the Bonfils intubation fibrescope than with the Macintosh (p = 0.001). However, the atlanto‐occipital distance was significantly greater during laryngoscopy with the Bonfils intubation fibrescope (p = 0.002), and the angle between the occiput and C1 differed significantly between the two techniques (p = 0.001). With the Bonfils intubation fibrescope, significantly less extension was also found at the C1/C2 and C3/C4 levels (p = 0.001 and p = 0.049, respectively). There is therefore significantly less movement of the upper cervical spine during laryngoscopy with the Bonfils fibrescope compared with the Macintosh laryngoscope.
The use of the stroke risk index to predict neurological complications following coronary revascularisation on cardiopulmonary bypass*
Authors: Elahi M. , Battula N. , Swanevelder J.
Published: June 2005

The aim of this study was to investigate the validity of the stroke risk index (SRI) in identifying patients who develop a stroke following coronary artery bypass grafting on cardiopulmonary bypass. Retrospective data were analysed from 6846 patients who underwent adult coronary artery surgical procedures on cardiopulmonary bypass between 1997 and 2003. Patients were risk stratified pre‐operatively using the SRI assessment model into low (Group A ≤ 50), medium (Group B, 51–100) and high risk (Group C, > 100). A total of 217 patients (3.2%) with a mean age 65.9 ± 11.7 years developed adverse neurological events following surgery. The CNS injury risk was 4% in Group A, 23% in Group B, and 8% in Group C. Pre‐operatively, patients in Group B were older (p < 0.05), had a greater proportion of redo operations (OR 3.02; p < 0.001), diabetes mellitus (OR 2.51; p < 0.05), hypertension (OR 1.64; p < 0.01), myocardial infarction (OR 3.79; p < 0.05), ejection fraction < 30% (OR 1.46; p < 0.01) and absence of sinus rhythm (OR 2.52; p < 0.05) when compared with their counterparts. CNS events increased the patients' hospital stay by 40% in Groups A and C (p = 0.04) and 72% in Group B (p < 0.001). Only 31% returned home, compared with 85% of patients without cerebral complications (p < 0.001). These findings demonstrate that factors such as a pre‐operative history of redo procedures, myocardial infarction, ejection fraction < 30% and absence of sinus rhythm play an important role in identifying the at‐risk population. We conclude, therefore, that a further refinement and validation of the SRI is necessary.
Effects of short‐term propofol administration on pancreatic enzymes and triglyceride levels in children
Authors: Gottschling S. , Meyer S. , Krenn T. , Kleinschmidt S. , Reinhard H. , Graf N. , Shamdeen G. M.
Published: June 2005

This prospective, clinical trial evaluated the effects of short‐term propofol administration on triglyceride levels and serum pancreatic enzymes in children undergoing sedation for magnetic resonance imaging. Laboratory parameters of 40 children, mean age (SD; range) 67 (66; 4–178) months undergoing short‐term sedation were assessed before and 4 h after having received propofol. Mean (SD) propofol loading dose was 2.2 (1.1) mg.kg−1 followed by continuous propofol infusion of 6.9 (0.9) mg.kg−1.h−1. Serum lipase levels (p = 0.035) and serum triglyceride levels (p = 0.003) were raised significantly after propofol administration but remained within normal limits. No significant changes in serum pancreatic‐amylase levels were seen (p = 0.127). In two (5%) children, pancreatic enzymes and in four (10%) children triglyceride levels were raised above normal limits; however, no child showed clinical symptoms of pancreatitis. We conclude that even short‐term propofol administration with standard doses of propofol may have a significant effect on serum triglyceride and pancreatic enzyme levels in children.
Distance between the skin and the thoracic paravertebral space
Authors: Naja M. Z. , Gustafsson A. C. , Ziade M. F. , El Rajab M. , Al‐Tannir M. , Daher M. , Lönnqvist P.A.
Published: June 2005

A fundamental requirement for the safe and effective performance of paravertebral blockade is reliable estimates of the depth from skin to paravertebral space at different thoracic levels. This distance was assessed using a nerve stimulator guided paravertebral blockade technique in 527 separate blocks in 186 patients scheduled for various surgical procedures on the trunk. The median skin‐paravertebral depth was 55.0 mm. The skin–paravertebral distance at upper (T1–3) and lower (T9–12) thoracic levels were significantly greater than mid‐thoracic levels (T4–8) (p < 0.05). Body mass index significantly influences this depth at upper and lower thoracic levels (p < 0.001) but not in the mid‐thoracic region.
Patterns of genetic variation do not correlate with geographical distance in the reef‐building coral Pocillopora meandrina in the South Pacific
Authors: MAGALON H. , ADJEROUD M. , VEUILLE M.
Published: June 2005

Dispersal may be a critical factor in the ability of reef‐building corals to recover after major disturbances. We studied patterns of geographical structure using four microsatellite markers in seven South Pacific populations of Pocillopora meandrina, a major coral species from Polynesia. Variation within populations showed evidence of heterozygote deficiency. Genetic differentiation between populations was detected at a large scale (2000 km) between the Tonga and the Society Islands. Within the Society Islands, four of the five studied populations from Bora Bora, Moorea and Tahiti were not significantly different from each other. Unexpectedly, one of the three populations surveyed in Moorea was genetically different from the other two populations of this island (that were 5 and 10 km apart), and from the populations of the other two surveyed islands in this archipelago. We cannot rule out the possibility that this pattern is an equilibrium state, whereby short‐range dispersal is locally more differentiating than long‐range dispersal, as has been suggested by similar patterns reported in other studies. An alternative explanation that is globally consistent with all observations is that this is the signature of a large‐scale destruction event, as for instance a bleaching event, followed by the recent restoration of populations by new colonists.
Migration patterns among global populations of the pathogenic fungus Mycosphaerella graminicola
Authors: BANKE S. , MCDONALD B. A.
Published: June 2005

DNA sequences from five nuclear loci and data from three microsatellites were collected from 360 isolates representing 14 globally distributed populations of the plant pathogenic fungus Mycosphaerella graminicola. Haplotype networks were constructed for the five sequence loci and population subdivision was assessed using Hudson's permutation test. Migration estimates were calculated using six regional populations for both the sequence and microsatellite loci. While subdivision was detected among the six regional populations, significant gene flow was indicated among some of the populations. The European and Israeli populations contributed the majority of historical immigrants to the New World. Migration estimates for microsatellite loci were used to infer more recent migration events among specific New World populations. We conclude that gene flow was an important factor in determining the demographic history of Mycosphaerella graminicola.
Host plant‐associated genetic differentiation in the snakeweed grasshopper, Hesperotettix viridis (Orthoptera: Acrididae)
Authors: SWORD G. A. , JOERN A. , SENIOR L. B.
Published: June 2005

Studies of herbivorous insects have played a major role in understanding how ecological divergence can facilitate genetic differentiation. In contrast to the majority of herbivorous insects, grasshoppers as a group are largely polyphagous. Due to this relative lack of intimate grasshopper–plant associations, grasshopper–plant systems have not played a large part in the study of host‐associated genetic differentiation. The oligophagous grasshopper, Hesperotettix viridis (Thomas), is endemic to North America and feeds on composites (Asteraceae) within the tribe Astereae. Previous work has shown both preference and performance differences between H. viridis individuals feeding on either Solidago mollis or Gutierrezia sarothrae. Using 222 AFLP markers, we examined the genetic relationships among 38 H. viridis individuals feeding on these plants both in sympatry and allopatry. Neighbour‐joining analysis resulted in two distinct host‐associated clades with 71% bootstrap support for host‐associated monophyly. Analyses of molecular variation (amova) revealed significant genetic structuring with host plant accounting for 20% of the total genetic variance while locality accounted for 0%. Significant genetic differentiation was detected between S. mollis‐feeders and G. sarothrae‐feeders even when the two were present at the same locality. These results are consistent with observed differences in preference and performance between H. viridis grasshoppers feeding on either G. sarothrae or S. mollis and indicate that H. viridis is comprised of at least two genetically distinct host plant‐associated lineages.
Genetic entities and mating system in hermaphroditicFucus spiralisand its close dioecious relativeF. vesiculosus(Fucaceae, Phaeophyceae)
Authors: ENGEL C. R. , DAGUIN C. , SERRÃO E. A.
Published: June 2005

To date, molecular markers have not settled the question of the specific status of the closely related, but phylogenetically unresolved, brown seaweeds, hermaphroditicFucus spiralisand dioeciousFucus vesiculosus, nor their propensity for natural hybridization. To test the degree of species integrity and to assess effect of the mating system on the population genetic structure, 288 individuals coming from parapatric (discontinuous) and sympatric (contiguous) spatial configurations at two sites were genotyped with five microsatellite loci. Using a Bayesian admixture analysis, our results show thatF. spiralisandF. vesiculosuscomprise clearly distinct genetic entities (clusters) generally characterized by cosexual and unisexual individuals, respectively. Genetic diversity within each entity suggests thatF. spiralisreproduces primarily through selfing whileF. vesiculosusis characterized by an endogamous breeding regime. Nevertheless, aberrant sexual phenotypes were observed in each cluster, no diagnostic alleles were revealed and 10% of study individuals were intermediate between the two genetic entities. This pattern can be explained by recent divergence of two taxa with retention of ancestral polymorphism or asymmetrical, introgressive hybridization. However, given (i) coincident monomorphism at three loci inspiralisclusters and (ii) that significantly more intermediates were observed in sympatric stations than in parapatric stations, we argue that interspecific gene flow has occurred after divergence of the two taxa. Finally, we show that whether recently separated or recently introgressive, the divergent breeding systems probably contribute to species integrity in these two taxa.
To what extent does living in a group mean living with kin?
Authors: LUKAS D. , REYNOLDS V. , BOESCH C. , VIGILANT L.
Published: June 2005

Chimpanzees live in large groups featuring remarkable levels of gregariousness and cooperation among the males. Because males stay in their natal communities their entire lives and are hence expected to be living with male relatives, cooperation is therefore assumed to occur within one large ‘family’ group. However, we found that the average relatedness among males within several chimpanzee groups as determined by microsatellite analysis is in fact rather low, and only rarely significantly higher than average relatedness of females in the groups or of males compared across groups. To explain these findings, mathematical predictions for average relatedness according to group size, reproductive skew and sex bias in dispersal were derived. The results show that high average relatedness among the philopatric sex is only expected in very small groups, which is confirmed by a comparison with published data. Our study therefore suggests that interactions among larger number of individuals may not be primarily driven by kin relationships.
How to use molecular marker data to measure evolutionary parameters in wild populations
Authors: GARANT DANY , KRUUK LOESKE E. B.
Published: June 2005

Estimating the genetic basis of phenotypic traits and the selection pressures acting on them are central to our understanding of the evolution and conservation of wild populations. However, obtaining such evolutionary‐related parameters is not an easy task as it requires accurate information on both relatedness among individuals and their breeding success. Polymorphic molecular markers are very useful in estimating relatedness between individuals and parentage analyses are now extensively used in most taxa. The next step in the application of molecular data to wild populations is to use them to derive estimates of evolutionary‐related parameters for quantitative traits, such as quantitative genetic parameters (e.g. heritability, genetic correlations) and measures of selection (e.g. selection gradients). Despite their great appeal and potential, the optimal use of molecular tools is still debated and it remains unclear how they should best be used to obtain reliable estimates of evolutionary parameters in the wild. Here, we review the methods available for estimating quantitative genetic and selection parameters and discuss their merits and shortcomings, to provide a tool that summarizes the potential uses of molecular data to obtain such parameters in wild populations.
Potential refugia in Taiwan revealed by the phylogeographical study of Castanopsis carlesii Hayata (Fagaceae)
Authors: CHENG YU‐PIN , HWANG SHIH‐YING , LIN TSAN‐PIAO
Published: June 2005

In this study, we examined spatial patterns of chloroplast DNA (cpDNA) variation in a total of 30 populations of Castanopsis carlesii Hayata (Fagaceae), a subtropical and temperate tree species, including 201 individuals sampled throughout Taiwan. By sequencing two cpDNA fragments using universal primers (the trnL intron and the trnV‐trnM intergenic spacer), we found a total of 1663 bp and 21 polymorphic sites. These gave rise to a total of 28 cpDNA haplotypes. The level of differentiation among the populations studied was relatively high (GST = 0.723). Two ancestral haplotypes are widely distributed. The Central Mountain Ridge (CMR) of Taiwan represents an insurmountable barrier to the east–west gene flow of C. carlesii. Among the populations studied, three separated populations, at Lienhuachih, Fushan and Lichia, have high nucleotide diversity. Estimates of NST–GST for populations on both sides of the CMR indicate that no phylogeographical structure exists. According to the genealogical tree, number of rare haplotype and population genetic divergence, this study suggests that two potential refugia existed during the last glaciation: the first refugium was located in a region to the north of Hsuehshan Range (HR) and west of the CMR; the second refugium was located in south, especially southeastern Taiwan. In fact, the second refugium happens to be the same as that reported for Quercus glauca. A ‘star‐like’ genealogy is characteristic when all haplotypes rapidly coalesce and is a general outcome of population expansion. The neutrality test and mismatch distribution also suggest demographic expansion recovering from a bottleneck.
Phylogeography of the cyprinid Squalius aradensis and implications for conservation of the endemic freshwater fauna of southern Portugal
Authors: MESQUITA N. , HÄNFLING B. , CARVALHO G. R. , COELHO M. M.
Published: June 2005

The Iberian cyprinid fauna, characterized by the presence of numerous endemic species, has suffered from significant habitat degradation. The critically endangered Squalius aradensis is restricted to small drainages of southern Portugal, habitats that typically exhibit a characteristic Mediterranean‐type heterogeneous hydrological system throughout the year, including alternation of flooding events during winter and complete drought in large river sections during summer. To assess the effect of historical and recent processes on genetic diversity in S. aradensis we examined within‐ and among‐population variability in cytochrome b and six polymorphic microsatellite loci. Estimates of genetic diversity in time and space through the combined use of traditional Φ‐/F‐statistics, phylogenetic trees, ordination methods and nested clade analysis indicated significant and congruent structuring among populations. Data suggest that the Arade drainage represent the evolutionary centre of the species, with subsequent allopatric fragmentation across drainages. Factors other than isolation by distance strongly affected the within‐drainage genetic differentiation observed in these Mediterranean‐type drainages, including recent population expansion from a bottleneck event and restricted gene flow imposed by a long‐term barrier (brackish water area). Significant correlation was found between S. aradensis allelic diversity and upstream drainage area. The relevance of findings for conservation issues is discussed in relation to local intermittent hydrological conditions, the highly restricted distribution and the critically endangered status of the species.
Habitat barriers limit gene flow and illuminate historical events in a wide‐ranging carnivore, the American puma
Authors: MCRAE B. H. , BEIER P. , DEWALD L. E. , HUYNH L. Y. , KEIM P.
Published: June 2005

We examined the effects of habitat discontinuities on gene flow among puma (Puma concolor) populations across the southwestern USA. Using 16 microsatellite loci, we genotyped 540 pumas sampled throughout the states of Utah, Colorado, Arizona, and New Mexico, where a high degree of habitat heterogeneity provides for a wide range of connective habitat configurations between subpopulations. We investigated genetic structuring using complementary individual‐ and population‐based analyses, the latter employing a novel technique to geographically cluster individuals without introducing investigator bias. The analyses revealed genetic structuring at two distinct scales. First, strikingly strong differentiation between northern and southern regions within the study area suggests little migration between them. Second, within each region, gene flow appears to be strongly limited by distance, particularly in the presence of habitat barriers such as open desert and grasslands. Northern pumas showed both reduced genetic diversity and greater divergence from a hypothetical ancestral population based on Bayesian clustering analyses, possibly reflecting a post‐Pleistocene range expansion. Bayesian clustering results were sensitive to sampling density, which may complicate inference of numbers of populations when using this method. The results presented here build on those of previous studies, and begin to complete a picture of how different habitat types facilitate or impede gene flow among puma populations.
Transgene escape: what potential for crop–wild hybridization?
Authors: ARMSTRONG T. T. , FITZJOHN R. G. , NEWSTROM L. E. , WILTON A. D. , LEE W. G.
Published: June 2005

To date, regional surveys assessing the risk of transgene escape from GM crops have focused on records of spontaneous hybridization to infer the likelihood of crop transgene escape. However, reliable observations of spontaneous hybridization are lacking for most floras, particularly outside Europe. Here, we argue that evidence of interspecific reproductive compatibility derived from experimental crosses is an important component of risk assessment, and a useful first step especially where data from field observations are unavailable. We used this approach to assess the potential for transgene escape via hybridization for 123 widely grown temperate crops and their indigenous and naturalized relatives present in the New Zealand flora. We found that 66 crops (54%) are reproductively compatible with at least one other indigenous or naturalized species in the flora. Limited reproductive compatibility with wild relatives was evident for a further 12 crops (10%). Twenty‐five crops (20%) were found to be reproductively isolated from all their wild relatives in New Zealand. For the remaining 20 crops (16%), insufficient information was available to determine levels of reproductive compatibility with wild relatives. Our approach may be useful in other regions where spontaneous crop–wild hybridization has yet to be well documented.
A new method for estimating the size of small populations from genetic mark–recapture data
Authors: MILLER CRAIG R. , JOYCE PAUL , WAITS LISETTE P.
Published: June 2005

The use of non‐invasive genetic sampling to estimate population size in elusive or rare species is increasing. The data generated from this sampling differ from traditional mark–recapture data in that individuals may be captured multiple times within a session or there may only be a single sampling event. To accommodate this type of data, we develop a method, named capwire, based on a simple urn model containing individuals of two capture probabilities. The method is evaluated using simulations of an urn and of a more biologically realistic system where individuals occupy space, and display heterogeneous movement and DNA deposition patterns. We also analyse a small number of real data sets. The results indicate that when the data contain capture heterogeneity the method provides estimates with small bias and good coverage, along with high accuracy and precision. Performance is not as consistent when capture rates are homogeneous and when dealing with populations substantially larger than 100. For the few real data sets where N is approximately known, capwire's estimates are very good. We compare capwire's performance to commonly used rarefaction methods and to two heterogeneity estimators in program capture: Mh‐Chao and Mh‐jackknife. No method works best in all situations. While less precise, the Chao estimator is very robust. We also examine how large samples should be to achieve a given level of accuracy using capwire. We conclude that capwire provides an improved way to estimate N for some DNA‐based data sets. Capwire is available at http://www.cnr.uidaho.edu/lecg/.
Identification and characterization of QTL underlying whole‐plant physiology in Arabidopsis thaliana: δ13C, stomatal conductance and transpiration efficiency
Authors: JUENGER THOMAS E. , MCKAY JOHN K. , HAUSMANN NEIL , KEURENTJES JOOST J. B. , SEN SÁUNAK , STOWE KIRK A. , DAWSON TODD E. , SIMMS ELLEN L. , RICHARDS JAMES H.
Published: June 2005

Water limitation is one of the most important factors limiting crop productivity world‐wide and has likely been an important selective regime influencing the evolution of plant physiology. Understanding the genetic and physiological basis of drought adaptation is therefore important for improving crops as well as for understanding the evolution of wild species. Here, results are presented from quantitative trait loci (QTL) mapping of flowering time (a drought escape mechanism) and carbon stable isotope ratio (δ13C) (a drought‐avoidance mechanism) in Arabidopsis thaliana. Whole‐genome scans were performed using multiple‐QTL models for both additive and epistatic QTL effects. We mapped five QTL affecting flowering time and five QTL affecting δ13C, but two genomic regions contained QTL with effects on both traits, suggesting a potential pleiotropic relationship. In addition, we observed QTL–QTL interaction for both traits. Two δ13C QTL were captured in near‐isogenic lines to further characterize their physiological basis. These experiments revealed allelic effects on δ13C through the upstream trait of stomatal conductance with subsequent consequences for whole plant transpiration efficiency and water loss. Our findings document considerable natural genetic variation in whole‐plant, drought resistance physiology of Arabidopsis and highlight the value of quantitative genetic approaches for exploring functional relationships regulating physiology.
Auxin and ethylene interactions control mitotic activity of the quiescent centre, root cap size, and pattern of cap cell differentiation in maize
Authors: PONCE GEORGINA , BARLOW PETER W. , FELDMAN LEWIS J. , CASSAB GLADYS I.
Published: June 2005

Root caps (RCs) are the terminal tissues of higher plant roots. In the present study the factors controlling RC size, shape and structure were examined. It was found that this control involves interactions between the RC and an adjacent population of slowly dividing cells, the quiescent centre, QC. Using the polar auxin transport inhibitor 1‐N‐naphthylphthalamic acid (NPA), the effects of QC activation on RC gene expression and border cell release was characterized. Ethylene was found to regulate RC size and cell differentiation, since its addition, or the inhibition of its synthesis, affected RC development. The stimulation of cell division in the QC following NPA treatment was reversed by ethylene, and quiescence was re‐established. Moreover, inhibition of both ethylene synthesis and auxin polar transport triggered a new pattern of cell division in the root epidermis and led to the appearance of supernumerary epidermal cell files with cap‐like characteristics. The data suggest that the QC ensures an ordered internal distribution of auxin, and thereby regulates not only the planes of growth and division in both the root apex proper and the RC meristem, but also regulates cell fate in the RC. Ethylene appears to regulate the auxin redistribution system that resides in the RC. Experiments with Arabidopsis roots also reveal that ethylene plays an important role in regulating the auxin sink, and consequently cell fate in the RC.
Circadian regulation of leaf hydraulic conductance in sunflower (Helianthus annuus L. cv Margot)
Authors: NARDINI ANDREA , SALLEO SEBASTIANO , ANDRI SERGIO
Published: June 2005

The circadian regulation of leaf hydraulic conductance (Kleaf) was investigated in Helianthus annuus L. (sunflower). Kleaf was measured with an high pressure flow meter during the light and dark period from plants growing at a photoperiod of 12 h. Kleaf was 4.0 e−4 kg s−1 m−2 MPa−1 during the light period (LL) and 30–40% less during the dark period (DL). When photoperiod was inverted and leaves were measured for Kleaf at their subjective light or dark periods, Kleaf adjusted to the new conditions requiring 48 h for increasing from dark to light values and 4 d for the opposite transition. Plants put in continuous dark showed Kleaf oscillating from light to dark values in phase with their subjective photoperiod indicating that Kleaf changes were induced by the circadian clock. Several cuts through the minor veins reduced leaf hydraulic resistance (Rleaf) of both LL and DL to the same value (1.0 e + 3 MPa m2 s kg−1) that equalled the vascular resistance (Rv). The contribution of the non‐vascular leaf resistance (Rnv) to Rleaf was of 71.9% in DL and of 58.4% in LL. The dominant Rnv was shown to be reversibly modulated by mercurials, suggesting that aquaporins play a role in diurnal changes of Kleaf.
Uptake and assimilation of nitrogen from solutions containing multiple N sources
Authors: THORNTON BARRY , ROBINSON DAVID
Published: June 2005

We assessed the extent to which plants can acquire amino acids when supplied as single N‐sources or when plants have access to a mixture of amino‐ and inorganic N sources. Because the uptake of different N‐sources is temperature‐dependent, the effects of temperature on amino‐N uptake were also tested. Lolium perenne (perennial rye‐grass) was grown hydroponically at 11 °C or 21 °C. Uptake of N was determined using 15N tracers at the growth temperature from solutions containing either nitrate, ammonium or glycine as single N sources and from a mixture containing all three N‐forms. Estimates of the relative importance of amino acids such as glycine to the total N budget of plants will have been underestimated in studies where uptake was determined in single source solutions compared with those from solutions containing a mixture of N‐forms. The proportion of total N acquired from the mixed N source as ammonium increased as temperature was reduced. Regarding the uptake and initial metabolism of glycine, uptake was probably the rate limiting step at 11 °C whilst it was the metabolism of glycine to serine at 21 °C. Although 15N incorporation into the plant amino‐N pool was generally in proportion to the abundance of individual amino acids, its incorporation into the glycine pool was sometimes significantly less than predicted.
Contact Between Good Friends: What Limiting Dilution Analysis Taught Us
Authors: Waldmann H.
Published: June 2005

The demonstration in the 1960s that T cells collaborated with B cells in enabling antibody responses to simple protein antigens opened up the challenge of how to investigate the interactions of two rare antigen‐specific lymphocytes within a vast population. One idea was that T cells made soluble factors that could activate B cells at a distance; the other was that rare T cells and B cells came into contact. Using limiting dilution analysis, we asked the question ‘How many B cells could a single T cell collaborate with in the short term?’ Unequivocally, the answer was just one. This implied a need for cell contact, and coupled with the observation for genetic restriction in T‐cell/B‐cell co‐operation, seemed to make a watertight case for direct coupling. Claims of diffusible antigen‐specific factors undermined the importance of our findings at that time. Remarkably, those claims have not yet been retracted and our original findings that collaborating T cells and B cells must come into contact have never achieved the recognition that they deserved.
IgM Accelerates Affinity Maturation
Authors: Corley R. B. , Morehouse E. M. , Ferguson A. R.
Published: June 2005

Secreted IgM is a potent adjuvant that concentrates antigen into secondary lymphoid organs and initiates antibody responses, germinal centre formation and is crucial in resolving infections. The current studies investigated the influence of specific IgM on both the quantity and quality of antibody produced in response to T‐dependent and T‐independent antigens. The addition of IgM to either antigen had no significant effect on the titre or duration of antibody responses. However, the presence of specific IgM led to accelerated affinity maturation when mice were challenged with low doses of IgM‐containing immune complexes (IgM‐IC) of T‐dependent antigens compared with antigen alone. Interestingly, the administration of higher concentrations of IgM‐IC increased follicular deposition of antigen but did not result in accelerated affinity maturation or in higher antibody affinities. The administration of IgM complexed with T‐independent antigens had no effect on antibody titre, duration or affinity maturation, despite increased antigen deposition in lymphoid follicles. Together, these results demonstrate that IgM accelerates affinity maturation in immune responses to T‐dependent antigens and implies an antigen optimum exists for the generation of high affinity antibodies. The data also suggest IgM plays an important role in the induction of CD4 T cells, facilitating germinal centre formation and function.
Household pit latrines as a potential source of the fly Musca sorbens– a one year longitudinal study from The Gambia
Authors: Emerson Paul M. , Simms Victoria M. , Makalo Pateh , Bailey Robin L.
Published: June 2005

Objectives  To assess whether the trachoma vector Musca sorbens was breeding in household latrines in a trachoma‐endemic part of The Gambia.

Methods  Longitudinal study of flies emerging from 16 sentinel household latrines selected at random from a list of all latrines present in four Gambian villages. Latrines were surveyed and fly traps were set over the drop hole for 24 h once per month for a year.

Results  All the sentinel latrines were of the ‘Gambian improved household latrine’ design, which has a cement slab but is not ventilated or fly‐proofed. The latrines were all in regular use by a family, mean number of users per latrine 14.8 (SD 8.0, range 2–29). Of 55 351 flies caught in 192 catches 54 130 (97.8%) were Chrysomya albiceps, 690 (1.2%) Musca domestica, 466 (0.8%) Chrysomya regalis and 65 (0.1%) M. sorbens. Of the M. sorbens caught 61 (93.8%) were female.

Conclusions  Gambian improved household pit latrines cannot be considered a source of the trachoma vector M. sorbens, and the promotion of pit latrines as a method to reduce M. sorbens is warranted. A large number of C. albiceps were caught emerging from the latrines, but this species is not considered to be of medical importance.
Predictors of compliance with community‐directed ivermectin treatment in Uganda: quantitative results
Authors: Nuwaha Fred , Okware Joseph , Ndyomugyenyi Richard
Published: June 2005

In order to identify the factors influencing compliance with mass ivermectin treatment for onchocerciasis control, a cross‐sectional study was carried out in Bushenyi District, Uganda. Data were collected by interviewing 839 individuals who were randomly selected from 30 clusters where onchocerciasis is endemic. Information was collected on compliance with ivermectin treatment, socio‐demographic characteristics, perception of personal susceptibility to onchocerciasis, knowledge about cause/transmission of onchocerciasis, knowledge of signs and symptoms of onchocerciasis, treatment of onchocerciasis, benefits and dangers of taking ivermectin, organization of distribution of ivermectin, work and selections of community drug distributors (CDDs), social influence and support to take ivermectin and on barriers and supports towards compliance with ivermectin treatment. The major factors favouring compliance were: perceiving CDDs as doing their work well, believing that measuring height is the best way to determine one's dose of ivermectin, having social support from one's family, saying that ivermectin treatment costs nothing, perceiving personal risk of onchocerciasis, believing that ivermectin prevents onchocerciasis and perceiving radios as supporting treatment with ivermectin. The strongest predictor of compliance with ivermectin treatment is perceiving CDDs as doing their work well with adjusted odds ratios of 5.54 (95% CI: 3.19–9.62). In order to improve compliance with ivermectin treatment, CDDs need to be well‐facilitated and ivermectin distribution should be free. Health education is necessary so that people perceive themselves to be at risk of onchocerciasis and to understand the rationale of using height for dose determination. The health education should target the family and use radios.
Antibacterial Activity of Synthetic Peptides Against Plant Pathogenic Pectobacterium Species
Authors: Kamysz W. , Krolicka A. , Bogucka K. , Ossowski T. , Lukasiak J. , Lojkowska E.
Published: June 2005

The aim of the work was to check the antibacterial activity of three synthetic peptides: CAMEL, Iseganan and Pexiganan as well as their possible application against plant pathogenic bacteria from the species Pectobacterium carotovorum (Pc) and Pectobacterium chrysanthemi (Pch). The antibacterial activity of the three chosen synthetic peptides was evaluated with the use of two tests: minimal inhibitory concentration and minimal bactericidal concentration. The CAMEL proved to be the most effective peptide, inhibiting the growth of different species of Pectobacterium in concentrations ranging from 2 to 8 μg/ml. Iseganan and Pexiganan also demonstrated activity against Pectobacterium sp., but it was lower than CAMEL. The CAMEL was able to inhibit Pc and Pch bacterial growth and tissue maceration in pathogenicity tests performed on potato tuber slices.
Photoinhibition and Recovery of Photosynthesis in Canker‐susceptible and Resistant Needles of Cypress (Cupressus sempervirens L.)
Authors: Muthuchelian K. , Bertamini M. , La Porta N. , Nedunchezhian N.
Published: June 2005

The aim of the present investigation was to test the hypothesis that the cypress canker caused by a fungus (Seiridium cardinale) infection induced effects on photosynthesis which could be related to photoinhibition and the process of recovery in susceptible and resistant needles. Photoinhibition of photosynthesis and recovery was studied in canker‐infected susceptible and resistant needles of cypress (Cupressus sempervirens L.) under controlled conditions (irradiation of detached needles to approximately 1900 μmol/m2/s). The degree of photoinhibition was determined by means of the ratio of variable to maximum chlorophyll (Chl) fluorescence (Fv/Fm) and electron transport measurements. The potential efficiency of photosystem (PS) II, Fv/Fm declined, and Fo increased significantly in canker‐susceptible needles, while Fo did not change in resistant needles. In isolated thylakoids, high light (HL) decreased the rate of whole chain and PS II activity markedly more in susceptible than in resistant needles. A smaller reduction of PS I activity was noticed only in susceptible needles. Upon subsequent dark incubation, fast recovery was noticed in both needle types and reached maximum rates of PS II efficiency similar to those noticed in non‐photoinhibited needles. The artificial exogenous electron donors such as diphenyl carbazide (DPC), NH2OH and Mn2+ failed to restore the HL induced loss of PS II activity in susceptible needles, while DPC and NH2OH significantly restored it in resistant needles. The results suggest that HL inactivates the donor side of PS II in resistant and the acceptor side of PS II in susceptible needles. The results on the quantification of the PS II reaction centre protein D1 and 33 kDa protein of water‐splitting complex following HL exposure showed pronounced differences between susceptible and resistant needles. The marked loss of PS II activity in HL‐irradiated needles was due to the marked loss of D1 protein in susceptible and 33 kDa protein in resistant needles, respectively.
Current trends of space occupation by encrusting excavating sponges on Colombian coral reefs
Authors: López‐Victoria Mateo , Zea Sven
Published: June 2005

Some sponges of the genus Cliona (Porifera, Hadromerida, Clionidae) simultaneously excavate and encrust calcareous substratum, competing aggressively for illuminated space with corals and other organisms. To interpret current trends of reef space occupation, the patterns of distribution and size of three Caribbean species were examined at San Andrés Island and Islas del Rosario in Colombia. While Cliona aprica was ubiquitous, C. caribbaea (= C. langae) preferred deep and protected reef zones, and C. tenuis shallow and wave‐exposed settings. In contrast to the effect on other excavating sponges, chronic exposure to raw sewage did not significantly increase the abundance of the studied sponges. Substratum occupation/availability ratios showed a positive tendency of the sponges toward certain coral skeletons, and a negative or neutral tendency toward calcareous rock, indicating that establishment may be easier on clean, recently dead coral than on older, heavily incrusted substratum. High relief generally limits sponge size to that of the illuminated portions of the substratum. A generally lower proportion of small individuals than of larger ones indicates currently low recruitment rates and low subsequent mortality. Successful events of higher recruitment seem to have occurred for C. tenuis. These are related to the massive acroporid coral die‐off in the early 1980s and to asexual dispersion during storms, resulting in a current 10% substratum cover. Reefs with high coral mortality were and/or are thus more susceptible to colonization and subsequent space occupation by these sponges, although relief may prevent space monopolization.
Factors affecting habitat occupancy of fish assemblage in the Gulf of Trieste (Northern Adriatic Sea)
Authors: Bonaca Martina Orlando , Lipej Lovrenc
Published: June 2005

Species composition, richness and abundance of the fish assemblage were studied over six different inshore macrohabitats in the southern part of the Gulf of Trieste (Northern Adriatic Sea) using the visual counts technique. Fifteen environmental variables were taken into consideration in order to determine microhabitat preferences of fish species, using canonical correspondence analysis and electivity indices. The results suggest that the structure of the fish assemblage in shallow habitats is affected by a large number of interplaying factors. Depth, type of bottom and vegetation cover – incorporating both abiotic and biotic variables – are some of the factors responsible for coastal fish distribution. Microhabitat preferences for 29 fish species are presented in the depth range from 0.5 to 3 m.