bluuebunny/crossref_metadata_2025_split huggingface dataset:
Leaf senescence is delayed in maize expressing the Agrobacterium IPT gene under the control of a novel maize senescence‐enhanced promoter
Authors: Robson Paul R. H. , Donnison Iain S. , Wang Kan , Frame Bronwyn , Pegg Sue Ellen , Thomas Ann , Thomas Howard 
Published: December 2004

SummaryWe have genetically modified maize plants to delay leaf senescence. A senescence‐enhanced promoter from maize (PSEE1) was used to drive expression of the Agrobacterium cytokinin biosynthesis gene IPT in senescing leaf tissue. Three maize lines expressing IPT from PSEE1, Sg1, Sg2 and Sg3, were analysed in detail, representing mild, intermediate and extreme expression, respectively, of the delayed‐senescence phenotype. Backcross populations segregating for the presence or absence of the PSEE1XbaIPTNOS transgene also simultaneously segregated for the senescence phenotype. At the time of ear leaf emergence, individuals of lines Sg1 and Sg2 segregating for the presence of the transgene carried about three fewer senescing leaves than control (transgene‐minus) segregants, and IPT transcript levels were higher in leaves at incipient senescence than in young leaves. Leaves of transgenic Sg3 plants were significantly greener than controls and progressed directly from fully green to bleached and dead without an intervening yellowing phase. IPT transcript abundance in this line was not related to the initiation of senescence. Extended greenness was accompanied by a delay in the loss of photosynthetic capacity with leaf age. The delayed‐senescence trait was associated with relatively minor changes in morphology and development. The phenotype was particularly emphasized in plants grown in low soil nitrogen. The reduced ability of the extreme transgenic line Sg3 to recycle internal nitrogen from senescing lower leaves accounted for significant chlorosis in emerging younger leaves when plants were grown in low nutrient conditions. This study demonstrates that the agronomically important delayed‐senescence (‘stay‐green’) trait can be engineered into a monocot crop, and is the first example outside Arabidopsis of senescence modification using a homologous senescence‐enhanced promoter.
Transgenic analysis of sugar beet xyloglucan endo‐transglucosylase/hydrolase Bv‐XTH1 and Bv‐XTH2 promoters reveals overlapping tissue‐specific and wound‐inducible expression profiles
Authors: Dimmer Emily , Roden Laura , Cai Daguang , Kingsnorth Crawford , Mutasa‐Göttgens Effie 
Published: December 2004

SummaryThe identification and analysis of tissue‐specific gene regulatory elements will improve our knowledge of the molecular mechanisms that control the growth and development of different plant tissues and offer potentially useful tools for the genetic engineering of plants. A polymerase chain reaction (PCR)‐based 5′‐genome walk from sequences of an isolated sugar beet xyloglucan endo‐transglucosylase hydrolase (XTH) gene led to the isolation of two independent upstream fragments. They were 1332 and 2163 base pairs upstream of the XTH ATG start site, respectively. In vivo transgenic assays in sugar beet hairy roots and Arabidopsis thaliana revealed that both fragments had promoter function and, in A. thaliana, directed expression in vascular tissues within the root, leaves and petals. Promoter activity was also observed in the leaf trichomes and within rapidly expanding stem internodes. Expression driven by both promoters was found to be wound inducible. Overall, the spatial and temporal expression pattern of these promoters suggested that the corresponding Bv‐XTH genes (designated Bv‐XTH1 and Bv‐XTH2) may be involved in secondary cell wall formation. This work provides new insights on molecular mechanisms that could be exploited for the genetic engineering of sugar beet crops.
Multivariate Outlier Detection in Incomplete Survey Data: The Epidemic Algorithm and Transformed Rank Correlations
Authors: Béguin Cédric , Hulliger Beat 
Published: December 2004

SummaryAs a part of the EUREDIT project new methods to detect multivariate outliers in incomplete survey data have been developed. These methods are the first to work with sampling weights and to be able to cope with missing values. Two of these methods are presented here. The epidemic algorithm simulates the propagation of a disease through a population and uses extreme infection times to find outlying observations. Transformed rank correlations are robust estimates of the centre and the scatter of the data. They use a geometric transformation that is based on the rank correlation matrix. The estimates are used to define a Mahalanobis distance that reveals outliers. The two methods are applied to a small data set and to one of the evaluation data sets of the EUREDIT project.
Combining Editing and Imputation Methods: An Experimental Application on Population Census Data
Authors: Manzari Antonia 
Published: December 2004

SummaryFeatures of census data make the editing and imputation phase a complex matter. Complex editing and imputation tasks can be tackled by dividing the editing and imputation process into subphases characterized by different problems, and finding appropriate solutions for each of them. An experimental application of the approach of combining different currently used methods for the editing and imputation of population census data is presented.
Defining new roles for plant and rhizobial molecules in sole and mixed plant cultures involving symbiotic legumes
Authors: Dakora Felix D. 
Published: December 2004

SummaryThe view that symbiotic legumes benefit companion and subsequent plant species in intercrop and rotation systems is well accepted. However, the major contributions made separately by legumes and their microsymbionts that do not relate to root‐nodule N2 fixation have been largely ignored. Rhizobia (species of Rhizobium, Bradyrhizobium, Azorhizobium, Allorhizobium, Sinorhizobium and Mesorhizobium) produce chemical molecules that can influence plant development, including phytohormones, lipo‐chito‐oligosaccharide Nod factors, lumichrome, riboflavin and H2 evolved by nitrogenase. When present in soil, Nod factors can stimulate seed germination, promote plant growth and increase grain yields of legume and nonlegume crops, as well as stimulate increased photosynthetic rates following plant leaf spraying. Very low concentrations of lumichrome and H2 released by bacteroids also promote plant growth and increase biomass in a number of plant species grown under field and glasshouse conditions. Rhizobia are known to suppress the population of soil pathogens in agricultural and natural ecosystems and, in addition to forming nodule symbioses with rhizobia, the legume itself releases phenolics that can suppress pathogens and herbivores, solubilize nutrients, and promote growth of mutualistic microbes. Phytosiderophores and organic acid anions exuded by the host plant can further enhance mineral nutrition in the system. This review explores new insights into sole and mixed plant cultures with the aim of identifying novel roles for molecules of legume and microbial origin in natural and agricultural ecosystems.
Ectomycorrhizas and retarded decomposition in aPinus resinosaplantation
Authors: Koide R. T. , Wu T. 
Published: December 2004

SummaryEctomycorrhizas may interact with saprotrophic microorganisms to influence decomposition. These interactions are poorly understood.We buried mesh envelopes filled with either litter or F‐layer material in the forest floor of aPinus resinosaplantation. After 16 months we characterized decomposition, C : N ratio, water content, and the density of four ectomycorrhiza morphotypes.For both substrates there were negative correlations between ectomycorrhiza density and decomposition, and between ectomycorrhiza density and water content. The relative proportion of morphotypes was significantly different in litter and F‐layer material buried at the same depth in the forest floor.We conclude that the negative effect of ectomycorrhizas on decomposition could be mediated by extraction of water, particularly in relatively dry years. The ‘Gadgil effect’ may be explained by this phenomenon. In wetter years, water extraction may be less consequential. Also, variation in substrate quality may influence the structure of ectomycorrhizal fungal communities.
Phytochelatin‐based complexes bind various amounts of cadmium in maize seedlings depending on the time of exposure, the concentration of cadmium and the tissue
Authors: Rauser Wilfried E. 
Published: December 2004

Summary

The aims were to determine the quantities of tissue cadmium (Cd) bound in maize (Zea mays) roots through phytochelatin‐based complexes with changes in time of exposure, the concentration of Cd, the part of the primary root system, and the status of the complexes in shoots.
Six buffer extractions solubilized most tissue Cd and a rapid small‐scale gel filtration resolved the buffer soluble Cd into high and low molecular weight Cd‐binding complexes.
Six buffer extractions, rather than one, effectively represented high and low molecular weight phytochelatin‐based Cd‐binding complexes. The low molecular weight complex predominated in root apices and after 1 d of 3 µm Cd; the high molecular weight complex predominated in mature root parts and after 2 d of exposure. More tissue Cd was bound by both complexes with increasing time of exposure and concentration of Cd. Buffer extracted less Cd from shoots than roots and phytochelatin‐based complexes bound less shoot Cd (29% vs 88%).
The phytochelatin‐based complexes are in a dynamic state dependent on the treatment and they function to bind variable amounts of tissue Cd.
Hybridization as a mechanism of invasion in oaks
Authors: Petit Rémy J. , Bodénès Catherine , Ducousso Alexis , Roussel Guy , Kremer Antoine 
Published: December 2004

SummaryWe review here our own research and related work on hybridization between two widespread and largely sympatric European oak species (Quercus petraeaandQ. robur). There is a near total lack of local differentiation in chloroplast DNA markers between them. A model is proposed to account for this lack of differentiation: invasion by one species of the range occupied by the other through pollen swamping. In support of this model, ecological, palaeoecological and population genetic studies indicate that one species (Q. robur) disperses its seeds better than the other one, that pollen flow is much more efficient than seed flow in oaks and that hybridization and introgression are asymmetric, hence reinforcing the ecological dynamics by facilitating the dispersal ofQ. petraeain regions already colonized byQ. robur. ‘Resurrection’ ofQ. petraeafollowing this wave of hybridization appears to be rapid. More generally, available evidence indicates that hybridization could constitute an important mechanism of dispersal in both natural and human‐induced plant invasions.
Historical inferences from the self‐incompatibility locus
Authors: Igic Boris , Bohs Lynn , Kohn Joshua R. 
Published: December 2004

SummaryAncient polymorphism preserved at the self‐incompatibility locus facilitates investigation of historical occurrences far older than extant species. We outline two ways in which studies of the S‐locus can provide insights into patterns of speciation. First, we review evidence concerning the prevalence of founder events in speciation. A dramatic population size reduction is expected to reduce sequence diversity at the S‐locus for millions of years. Only one potential bottleneck is preserved at the S‐locus of the Solanaceae, suggesting that severe population size restrictions rarely occur in successful lineages. This must be interpreted with caution because of the restrictive conditions under which bottlenecks at the S‐locus will be preserved. Second, S‐locus polymorphism provides a novel opportunity to reconstruct, with considerable certainty, the presence or absence of self‐incompatibility among ancestral taxa. We demonstrate this approach using a phylogenetic analysis and find that transitions from self‐incompatibility to self‐compatibility are common and essentially irreversible in the Solanaceae. Self‐incompatibility is ancestral, but self‐compatible taxa currently outnumber self‐incompatible ones. Either self‐incompatibility is going extinct, or the presence of incompatibility increases the diversification rate, maintaining a mixture of self‐incompatible and self‐compatible species in equilibrium. We outline how phylogenetic approaches can be used to determine the effect of incompatibility on diversification.
Respiratory sinus arrhythmia as an index of emotional response in young adults
Authors: Frazier Thomas W. , Strauss Milton E. , Steinhauer Stuart R. 
Published: December 2004

AbstractThe relationship between respiratory sinus arrhythmia (RSA) and valence and arousal remains unclear. In the present study, the associations between emotion responses and tonic or task‐related changes in RSA were assessed. Specifically, the sensitivities of changes in interbeat interval, RSA, and skin conductance to the valence and arousal values of emotional stimuli were examined. This study also explored the association between tonic RSA and subjective, expressive, and physiological emotional responses. Response measures were collected from 56 adults during baseline and film‐viewing periods. Tonic RSA was not significantly related to any of the response measures. Increased skin conductance and decreased RSA were associated with arousal independent of valence. Interbeat interval was related to affective valence and not arousal. These findings suggest that RSA may be a useful adjunct to skin conductance measures in assessing emotional arousal.
Role of Legumes in Release of Successionally Arrested Grasslands in the Central Hills of Sri Lanka
Authors: Ashton P. M. S. , Samarasinghe S. J. , Gunatilleke I. A. U. N. , Gunatilleke C. V. S. 
Published: December 2004

AbstractMost of the world's forest has been cleared, cultivated, and then often abandoned. In many instances these areas have changed to successionally arrested grasslands, shrublands, or fernlands maintained by frequent fires and high herbivore populations. Many studies have shown that various herbaceous, nitrogen‐fixing legumes can protect soil surfaces, retain soil moisture, improve soil fertility, and retard ground fires. Our objective was to ascertain if some of these species can potentially inhibit herbivory and satisfactorily establish in these arrested grassland areas to serve as sites for reforestation. We evaluated the potential for four species of nitrogen‐fixing legumes (Calapogonium mucunoides, Centrosema pubescens, Desmodium ovalifolium, andPueraria phaseoloides) to establish on exposed soil within successionally arrested grasslands ofPanicum maximumandCymbopogon nardusin the central hills of Sri Lanka. Four different sites within rectangular grassland areas were cleared of graminoids and sown with seed of each legume. Half of each clearing was protected from browsing rabbits and porcupines, and half was not protected. After 6 months, certain plots were destructively sampled to determine dry biomass gain for each species and treatment. Analyses of variance were performed to test for differences among sites, treatments, and species. All three factors revealed differences, indicating that species must be matched to site. On sites with high amounts of herbivory,D. ovalifoliumhad the greatest dry biomass gain after 6 months of growth, possibly because of its relatively low nitrogen and moisture content. Where herbivory was absent,P. phaseoloidesandC. muconoideshad the greatest dry biomass gain. Dry biomass gain of all four legume ground covers was low on sites with lowest pH and nutrient concentrations. Under conditions of low relative fertility and low pH, establishment of the tested legumes failed. Though soil moisture availability was not measured, we speculate that these low fertility sites were also prone to drought. Findings support the site‐specific establishment of legume species for purposes of reforestation and watershed protection in central Sri Lanka. This work is applicable to other regions particularly dominated by successionally arrested grasslands with similar circumstances in other parts of south and southeast Asia.
Stabilization and Erosion Control Value of Oyster Cultch for Intertidal Marsh
Authors: Meyer David L. , Townsend Edward C. , Thayer Gordon W. 
Published: December 2004

AbstractOyster cultch was added to the lower intertidal fringe of three created Spartina alterniflora marshes to examine its value in protecting the marsh from erosion. Twelve 5‐m‐wide plots were established at each site, with six randomly selected plots unaltered (non‐cultched) and cultch added to the remaining (cultched) plots. Within each cultched plot, cultch was placed along the low tide fringe of the marsh during July 1992, in a band 1.5 m wide by 0.25 m deep. Marsh‐edge vegetation stability and sediment erosion were measured for each plot from September 1992 to April 1994. Significant differences (p < 0.05) in marsh‐edge vegetation change were detected at the only south‐facing site after a major southwester storm. Significantly different rates of sediment erosion and accretion also were observed at this same site. Areas upland of the marsh edge in the cultched areas showed an average accretion of 6.3 cm, while noncultched treatment areas showed an average loss of 3.2 cm. A second site, with a northern orientation, also experienced differential sediment accretion and erosion between treatment type, caused instead by boat wakes that were magnified by the abutment of a dredge effluent pipe across the entire front fringe of the site. During this period we observed significant differences in sediment accumulation, with the areas upland of the marsh edge in the cultched treatment having an average accretion of 2.9 cm and the noncultched an average loss of 1.3 cm.
The Possible Role of Natural Idiotopes in Immune Memory
Authors: Dimitrijević Ljiljana , Živanević-Simonović Snezana , Stojanović Marijana , Inić-Kanada Aleksandra , Živković Irena 
Published: December 2004

In this paper we report on the generation of Abs possessing specificities
similar to those of Abs used in immunization, and on the generation of Id and
anti‐Id
specificities in the sera of mice immunized with commensal bacterial antigens.The human monoclonal antibody IgM DJ (VH3/VL2) expresses natural
antibody properties, natural idiotope (Y7), and specificity towards Lactic acid
bacteria (LAB). When used in immunization it generates LAB‐specific antibodies.
Immunization with LAB, as detected in the presence of biotin‐labelled mouse
monoclonal anti‐idiotopic antibodies Y7 and IgM DJ generates Abs1 and Abs2,
respectively. These findings may imply that the recognition of bacterial motifs
accords with the rules of idiotypic network theory. This theory, first proposed by
Jerne in 1974 and often overlooked since, has been subject to change during the
course of immunological research. Recent experiments concerning the recognition
of bacterial motifs and natural memory in the immune system have inspired us in
our attempt at explaining the possible role of natural Id in immune memory.
Early Appearance of TNF‐α and Other Cytokines in Bronchus Associated Lymphoid Tissues (BALT) from Growing Wistar Rats. What is the Role of TNF‐α?
Authors: Delettieres Dreanina , Frecha Cecilia A. , Roux Maria E. 
Published: December 2004

Several different cytokines trigger the development of determined cell subsets
in BALT of growing Wistar rats. Early appearance (4 days post partum) of γδT cells in
BALT has been shown, as well as its role in up‐regulating TNF‐α production. In the
present report, we studied in the BALT: (1) the profile of the cytokines, TNF‐α, INF‐γ
and IL‐10 and (2) in TCR γδ+ cells, the existence of a colocalization with TNF‐α as well
as with INF‐γ. All the cytokines studied were observed at an early stage of BALT
development by immunohistochemistry and in bronchoalveolar cells (BAL cells) by
flow cytometry and western blot. (1) The principal cytokine found at 4 days of age in
BALT cells was TNF‐α that increases along BALT development. The same behavior
was found for cells containing IL‐10 and INF‐γ. (2) TCR γδ+ cells colocalize mainly with
TNF‐α as it has been shown by immunohistochemistry in BALT and by flow cytometry
when we studied BAL.The early appearance of TNF‐α concomitant with TCR γδ+ cell suggests
an important role for this cytokine along BALT development. Moreover, mutual
regulation between them exists taking
part in the immune surveillance and repair of damaged epithelia.
Levels of Reality
Authors: Heil John 
Published: December 2004

AbstractPhilosophers and non‐philosophers have been attracted to the idea that the world incorporates levels of being: higher‐level items – ordinary objects, artifacts, human beings – depend on, but are not in any sense reducible to, items at lower levels. I argue that the motivation for levels stems from an implicit acceptance of a Picture Theory of language according to which we can ‘read off’ features of the world from ways we describe the world. Abandonment of the Picture Theory opens the way to a ‘no levels’ conception of reality, a conception that honors anti‐reductionist sentiments and preserves the status of the special sciences without the ontological baggage.
Intentionality and Self‐Awareness
Authors: Perrett Roy W. 
Published: December 2004

AbstractIn this essay I defend both the individual plausibility and conjoint consistency of two theses. One is the Intentionality Thesis: that all mental states are intentional (object‐directed, exhibit ‘aboutness’). The other is the Self‐Awareness Thesis: that if a subject is aware of an object, then the subject is also aware of being aware of that object. I begin by arguing for the individual prima facie plausibility of both theses. I then go on to consider a regress argument to the effect that the two theses are incompatible. I discuss three responses to that argument, and defend one of them.
Minimum and maximum entitlements: literature at Key Stage 2
Authors: Martin Tony 
Published: December 2004

AbstractHow far does the difference between a child's minimum reading entitlement (“I can read different types of text for different purposes – and I've got level 4 to prove it”) and maximum entitlement (“I recognise the power of literature and want to read it for the rest of my life”) encapsulate a tension present in many primary classrooms? In England, literature (poetry, narrative, plays) is taught as part of the National Literacy Strategy and a child's knowledge of how it works may be assessed if literary texts are included in the end of Key Stage 2 reading test. The requirements of the Strategy and especially the reading test may well impact on the maximum entitlement of a child to become a reader for life. This article explores some of the dangers which result from viewing the minimum entitlement as the maximum being aimed at in the classroom.
Using Difference-Based Methods for Inference in Nonparametric Regression with Time Series Errors
Authors: Hall Peter , Keilegom Ingrid Van 
Published: December 2004

SummaryWe show that difference-based methods can be used to construct simple and explicit estimators of error covariance and autoregressive parameters in nonparametric regression with time series errors. When the error process is Gaussian our estimators are efficient, but they are available well beyond the Gaussian case. As an illustration of their usefulness we show that difference-based estimators can be used to produce a simplified version of time series cross-validation. This new approach produces a bandwidth selector that is equivalent, to both first and second orders, to that given by the full time series cross-validation algorithm. Other applications of difference-based methods are to variance estimation and construction of confidence bands in nonparametric regression.