bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plant litter chemistry and mycorrhizal roots promote a nitrogen feedback in a temperate forest
Authors: Wurzburger Nina , Hendrick Ronald L. 
Published: March 2009

Summary

Relationships between mycorrhizal plants and soil nitrogen (N) have led to the speculation that the chemistry of plant litter and the saprotrophy of mycorrhizal symbionts can function together to closely couple the N cycle between plants and soils. We hypothesized that a tannin‐rich, ericoid mycorrhizal (ERM) plant promotes the retention of protein–tannin N in soil, and that this N source is accessible to saprotrophic ERM symbionts and their hosts, but remains less available to co‐occurring ectomycorrhizal (ECM) and arbuscular mycorrhizal (AM) symbionts and their hosts.
We tested this feedback hypothesis in a southern Appalachian forest community composed of two microsites: a hardwood microsite with ECM and AM trees in the overstorey and understorey, and an AM herb layer; and a rhododendron microsite where the understorey and herb layer are replaced by ERM rhododendron. We synthesized 15N‐enriched protein–tannin complexes from leaf litter extracts representing each forest microsite and examined the fate of 15N in soil volumes 3 months and 1 year after the complexes were placed in the field.
Protein–tannin complexes derived from the rhododendron microsite led to a higher retention of 15N in soil organic matter and a lower recovery in dissolved N pools than those from the hardwood microsite, supporting the hypothesis that rhododendron tannins create stable complexes that increase organic N retention in soils.
Rhododendron complexes led to greater 15N‐enrichment in ERM roots than in AM and ECM roots, supporting the hypothesis that rhododendron can better access the N complexed by its own litter tannins than can co‐occurring forest trees and plants. Our results suggest that both fungal saprotrophy and a high specific root length contribute to the ability of ERM roots to acquire N from complex organic sources.
Synthesis. This study provides evidence of an intricate N feedback where plant litter chemistry influences the cycle of N to maximize N acquisition by the host's mycorrhizal roots, while hindering N acquisition by mycorrhizal roots of co‐occurring plants. Feedback processes such as these have the potential to drive patterns in nitrogen cycling and productivity in many terrestrial ecosystems.
Biodiversity in microbial communities: system scale patterns and mechanisms
Authors: PARNELL J. JACOB , CROWL TODD A. , WEIMER BART C. , PFRENDER MICHAEL E. 
Published: March 2009

AbstractThe relationship between anthropogenic impact and the maintenance of biodiversity is a fundamental question in ecology. The emphasis on the organizational level of biodiversity responsible for ecosystem processes is shifting from a species‐centred focus to include genotypic diversity. The relationship between biodiversity measures at these two scales remains largely unknown. By stratifying anthropogenic effects between scales of biodiversity of bacterial communities, we show a statistically significant difference in diversity based on taxonomic scale. Communities with intermediate species richness show high genotypic diversity while speciose and species‐poor communities do not. We propose that in species‐poor communities, generally comprising stable yet harsh conditions, physiological tolerance and competitive trade‐offs limit both the number of species that occur and the loss of genotypes due to decreases in already constrained fitness. In species‐rich communities, natural environmental conditions result in well‐defined community structure and resource partitioning. Disturbance of these communities disrupts niche space, resulting in lower genotypic diversity despite the maintenance of species diversity. Our work provides a model to inform future research about relationships between species and genotypic biodiversity based on determining the biodiversity consequences of changing environmental context.
Contribution of cyclic parthenogenesis and colonization history to population structure in Daphnia
Authors: THIELSCH ANNE , BREDE NORA , PETRUSEK ADAM , DE MEESTER LUC , SCHWENK KLAUS 
Published: March 2009

AbstractCyclic parthenogenesis, the alternation of parthenogenetic and sexual reproduction, can lead to a wide scope of population structures, ranging from almost monoclonal to genetically highly diverse populations. In addition, sexual reproduction in aquatic cyclic parthenogens is associated with the production of dormant stages, which both enhance potential gene flow among populations as well as impact local evolutionary rates through the formation of dormant egg banks. Members of the cladoceran genus Daphnia are widely distributed key organisms in freshwater habitats, which mostly exhibit this reproduction mode. We assessed patterns of genetic variation within and among populations in the eurytopic and morphologically variable species Daphnia longispina, using data from both nuclear (13 microsatellite loci) and mitochondrial (partial sequencing of the 12S rRNA gene) markers from a set of populations sampled across Europe. Most populations were characterized by very high clonal diversity, reflecting an important impact of sexual reproduction and low levels of clonal selection. Among‐population genetic differentiation was very high for both nuclear and mitochondrial markers, and no strong pattern of isolation by distance was observed. We also did not observe any substantial genetic differentiation among traditionally recognized morphotypes of D. longispina. Our findings of high levels of within‐population genetic variation combined with high among‐population genetic differentiation are in line with predictions of the monopolization hypothesis, which suggests that in species with rapid population growth and potential for local adaptation, strong priority effects due to monopolization of resources lead to reduced levels of gene flow.
Peroxule extension over ER‐defined paths constitutes a rapid subcellular response to hydroxyl stress
Authors: Sinclair Alison M. , Trobacher Chris P. , Mathur Neeta , Greenwood John S. , Mathur Jaideep 
Published: March 2009

SummaryPlants survive against myriad environmental odds while remaining rooted to a single spot. The time scale over which plant cells can respond to environmental cues is seldom appreciated. Fluorescent protein‐assisted live imaging of peroxisomes reveals that they respond within seconds of exposure to hydrogen peroxide and hydroxyl radicals by producing dynamic extensions called peroxules. Observations of the Arabidopsis flu mutant and treatments with xenobiotics eliciting singlet oxygen and superoxide reactive oxygen species suggest that the observed responses are specific for hydroxyl radicals. Prolonged exposure to hydroxyl radicals inhibits peroxule extension, and instead causes motile and spherical peroxisomes in a cell to become immotile and elongate several‐fold. Expression of photo‐convertible EosFP–PTS1 demonstrates that vermiform peroxisomes result from rapid stretching of individual peroxisomes, while the subsequent ‘beads‐on‐a‐string’ morphology results from differential protein distribution within an elongated tubule. Over time, the beads in elongated peroxisomes also extend peroxules randomly before undergoing asynchronous, asymmetrical fission. Peroxule extension does not appear to involve cytoskeletal elements directly, but is closely aligned with and reflects the dynamics of ER tubules. Peroxisomal responses reveal a rapidly invoked subcellular machinery that is involved in recognition of hydroxyl stress thresholds, and its possible remediation locally through extension of peroxules or globally by increasing peroxisome numbers. A matrix protein retro‐flow mechanism that supports peroxisome–ER connectivity in plant cells is suggested.
Which model species for weed seedbank and emergence studies? A review
Authors: GARDARIN A , DÜRR C , COLBACH N 
Published: March 2009

Gardarin A, Dürr C & Colbach N (2009). Which model species for weed seedbank and emergence studies? A review. Weed Research49, 117–130.SummaryModels predicting the effects of cropping systems on weed demography are important tools for testing new rules for integrated weed management that may reduce the use of herbicides and preserve the biodiversity of agro‐ecosystems. Such models already exist for a few species and should now be extended to a larger flora, in order to predict and understand the effects of agricultural practices on the evolution of weed communities. This review analysed the literature from 1973 to 2006, focusing on 45 species, to identify past reasons for choosing particular species when modelling the effects of cropping systems on the processes leading to seedling emergence. The frequency or harmfulness of the species were the main reason for studying them. It appears that the studied species were mainly autumn‐emerging in north‐western Europe cropping systems and summer‐emerging in North America; the effects of deep soil tillage were studied mainly in Europe, as simplified sowing techniques are more often practised in North America. A voluminous literature exists on seed persistence in the soil, dormancy, germination and emergence, but rarely with the attempt of establishing generic relationships between species characteristics and model parameters. Until now, such an approach has been mostly developed in ecological studies. Taxa, as well as ecological preferences, seed size and the relationships of these characteristics with weed emergence model parameters should be considered when selecting a range of species for multi‐specific modelling purposes.
A novel strain of Fusarium oxysporum from Germany and its potential for biocontrol of Orobanche ramosa
Authors: MÜLLER‐STÖVER D , KOHLSCHMID E , SAUERBORN J 
Published: March 2009

Müller‐stöver D, Kohlschmid E & Sauerborn J (2009). A novel strain of Fusarium oxysporum from Germany and its potential for biocontrol of Orobanche ramosa. Weed Research.49, 175–182.SummaryA newly isolated Fusarium oxysporum strain was investigated for its biocontrol potential against the root parasitic weed Orobanche ramosa (branched broomrape). The fungus was found to affect all developmental stages of the parasite. Orobanche seed germination was reduced by 40% in the presence of fungal conidia in vitro. The number of underground tubercles and shoots of the weed was reduced by the fungus by 55% compared with the control and 92% of tubercles were recorded as diseased in root chambers. In pot experiments, soil application of a granular formulation of the fungus resulted in a reduction of number and dry matter of Orobanche shoots by more than 90%. Spraying of a conidial suspension on aboveground Orobanche shoots caused the death of 75% of them within 2 weeks. Data from initial host‐range experiments indicate that the isolate is very host‐specific, not even attacking shoots of other Orobanche species. Because of these promising results, we conclude that the fungal isolate should be investigated under field conditions and be compared with other Fusarium isolates proposed for biocontrol of O. ramosa.
Investigating genetic diversity and habitat dynamics in Plantago brutia (Plantaginaceae), implications for the management of narrow endemics in Mediterranean mountain pastures
Authors: De Vita A. , Bernardo L. , Gargano D. , Palermo A. M. , Peruzzi L. , Musacchio A. 
Published: March 2009

AbstractMany factors have contributed to the richness of narrow endemics in the Mediterranean, including long‐lasting human impact on pristine landscapes. The abandonment of traditional land‐use practices is causing forest recovery throughout the Mediterranean mountains, by increasing reduction and fragmentation of open habitats. We investigated the population genetic structure and habitat dynamics of Plantago brutia Ten., a narrow endemic in mountain pastures of S Italy. Some plants were cultivated in the botanical garden to explore the species’ breeding system. Genetic diversity was evaluated based on inter‐simple sequence repeat (ISSR) polymorphisms in 150 individuals from most of known stands. Recent dynamics in the species habitat were checked over a 14‐year period. Flower phenology, stigma receptivity and experimental pollinations revealed protogyny and self‐incompatibility. With the exception of very small and isolated populations, high genetic diversity was found at the species and population level. amova revealed weak differentiation among populations, and the Mantel test suggested absence of isolation‐by‐distance. Multivariate analysis of population and genetic data distinguished the populations based on genetic richness, size and isolation. Landscape analyses confirmed recent reduction and isolation of potentially suitable habitats. Low selfing, recent isolation and probable seed exchange may have preserved P. brutia populations from higher loss of genetic diversity. Nonetheless, data related to very small populations suggest that this species may suffer further fragmentation and isolation. To preserve most of the species’ genetic richness, future management efforts should consider the large and isolated populations recognised in our analyses.
Comparison of the guaranteed analysis with the measured nutrient composition of commercial pet foods
Authors: Choate C. J. , Hill R. C. , Scott K. C. , Molenberghs G. 
Published: March 2009

The purpose of this study was to compare the guaranteed analysis of commercial pet foods to their measured nutrient concentrations. Data were collected regarding the guaranteed and measured concentrations of crude protein, crude fat, crude fibre, moisture and ash of pet foods from annual feed inspection reports from South Dakota (2003–2005), Indiana (2004–2005), Rhode Island, New York and New Jersey (2005–2006). The difference for each nutrient was compared among types of food (dry, canned or treat), intended species, target life‐stages, manufacturers and reporting laboratories.Significant differences between the guaranteed and measured nutrient concentrations were found. For all foods, the mean ± one standard deviation of the difference was 1.5 ± 2.0% for crude protein, 1.0 ± 1.7% for crude fat, ‐0.7 ± 1.3% for crude fibre, ‐4.0 ± 3.3% for moisture, and ‐0.5 ± 1.0% for ash. The difference in crude protein was significantly greater for treats than for other food types. The difference in crude fat was significantly less for dry foods than for other food types. The differences in crude fibre and moisture were significantly less for canned foods than for other food types. Only the differences in crude fibre differed significantly among target species, life‐stages, manufacturers or laboratories.More accurate estimations of the nutrient composition and calculated metabolizable energy content of commercial pet foods can be obtained by making adjustments to the guaranteed analysis. This includes adding 1.5% and 1% to the guaranteed minimums for crude protein and crude fat, respectively, and subtracting 0.7%, 4% and 0.5% from the guaranteed maximums for crude fibre, moisture and ash, respectively.
Olfactory response of Stenotus rubrovittatus to rice and paddy weed, Scirpus juncoides
Authors: Hori M. 
Published: March 2009

AbstractThe olfactory response of the sorghum plant bug, Stenotus rubrovittatus (Matsumura) (Het., Miridae), to rice, Oryza sativa L., and paddy weed, Scirpus juncoides Roxb. var. ohwianus T. Koyama, was investigated with an olfactometer to clarify the mechanism of the invasion of the bugs in paddy fields. Both adult females and males were significantly attracted to panicles of rice in the flowering and full‐ripe stages. Whole plants (aboveground parts) of rice in the panicle‐formation stage, and stems and leaves of rice in the flowering stage significantly attracted only adult females. Other rice structures tested did not attract males or females. Both males and females were attracted to the flowering spikelets of S. juncoides. Although females showed no olfactory response to stems of S. juncoides in the flowering stage, males were repelled by them. Only females were attracted to whole plants of flowering S. juncoides. Whole plants of S. juncoides in the spikelet‐formation stage significantly attracted only females. The findings suggest that the invasions of S. rubrovittatus into paddy fields are caused by their olfactory responses to the volatiles emitted from rice and some paddy weeds such as S. juncoides.
The changing face of epidemiology of invasive fungal disease in Europe
Authors: Lass‐Flörl Cornelia 
Published: March 2009

SummaryInvasive fungal diseases (IFDs) are an increasingly common complication in critically ill patients in Europe and are frequently fatal. Because of changes in treatment strategies and the increased use of antifungal prophylaxis, the epidemiology of IFDs has changed substantially in recent years and infections due to Candida species are no longer the majority in many institutions. In contrast, the emergence of non‐Candida IFDs such as aspergillosis, zygomycosis and fusariosis has increased. European surveys indicate that Candida albicans is responsible for more than half the cases of invasive candidaemia; however, the occurrence of non‐albicans‐related IFDs appears to be increasing. Rates of IFD‐related mortality in Europe depend on the pathogen, geographical location and underlying patient characteristics, with rates ranging from 28 to 59% for Candida infections and from 38 to 80% for invasive aspergillosis. Early initiation of antifungal therapy is critical for improving outcomes; however, this is complicated by the difficulty in diagnosing IFDs rapidly and accurately. The introduction of new extended‐spectrum azole antifungal agents (e.g. voriconazole, posaconazole) and echinocandins (e.g. micafungin, caspofungin, anidulafungin) has increased the number of therapeutic options for early therapy. Choice between agents should be based on a variety of factors, including spectrum of activity, adverse events, drug interactions, route of administration, clinical efficacy of individual agents and local epidemiology.
Continuity of nursing and the time of sickness
Authors: Elstad Ingunn , Torjuul Kirsti 
Published: March 2009

AbstractThis paper explores the relationship between temporal continuity in nursing and temporal features of sickness. It is based on phenomenological and hermeneutical philosophy, empirical studies of sickness time, and the nursing theories of Nightingale, of Benner and of Benner and Wrubel. In the first part, temporal continuity is defined as distinct from interpersonal continuity. Tensions between temporal continuity and discontinuity are discussed in the contexts of care management, of conceptualisations of disease and of time itself. Temporal limitations to the methodological concept of situation are discussed. The main part of this paper explores nurses’ possibilities to relate to their patients’ time, and how temporal features of sickness may warrant temporal continuity of nursing. Three temporal characteristics of sickness are discussed: the immediacy of patients’ suffering, the basic continuity of life through sickness and health care, and the indeterminism and precariousness of sickness. The timing of nursing acts is discussed. The paper explores how sickness is both part of the continuity of life, and threatens this continuity. It concludes that this tension is implicitly recognised in the temporal continuity of nursing, which allows for discontinuous and continuous aspects of sickness time. Nurses accordingly perceive the sick person's time at several levels of temporality, and distinguish highly complex temporal processes in their patients’ trajectory. Temporal continuity provides the time, flexibility, and closeness for nurses to perceive and act into time dimensions of individual sickness. The paper shows that temporal continuity of nursing is grounded in temporal characteristics of severe sickness. It suggests that temporal continuity is an important theoretical concept in nursing.
Noddings's caring ethics theory applied in a paediatric setting
Authors: Lundqvist Anita , Nilstun Tore 
Published: March 2009

AbstractSince the 1990s, numerous studies on the relationship between parents and their children have been reported on in the literature and implemented as a philosophy of care in most paediatric units. The purpose of this article is to understand the process of nurses' care for children in a paediatric setting by using Noddings's caring ethics theory. Noddings's theory is in part described from a theoretical perspective outlining the basic idea of the theory followed by a critique of her work. Important conceptions in her theory are natural caring (reception, relation, engrossment, motivational displacement, reciprocity) and ethical caring (physical self, ethical self, and ethical ideal). As a nurse one holds a duty of care to patients and, in exercising this duty, the nurse must be able to develop a relationship with the patient including giving the patient total authenticity in a ‘feeling with’ the patient. Noddings's theory is analysed and described in three examples from the paediatrics. In the first example, the nurse cared for the patient in natural caring while in the second situation, the nurse strived for the ethical caring of the patient. In the third example, the nurse rejected the impulse to care and deliberately turned her back to ethics and abandoned her ethical caring. According to the Noddings's theory, caring for the patient enables the nurse to obtain ethical insights from the specific type of nursing care which forms an important contribution to an overall increase of an ethical consciousness in the nurse.
The pleiotropic effects of the bar gene and glufosinate on the Arabidopsis transcriptome
Authors: Abdeen Ashraf , Miki Brian 
Published: March 2009

SummaryThe Arabidopsis transcriptome was studied using the Affymetrix Arabidopsis ATH1 GeneChip in wild‐type plants and glufosinate‐tolerant transgenic plants expressing the bialaphos resistance (bar) gene. Pleiotropic effects were specifically generated in the transcriptomes of transgenic plants by both the bar gene and glufosinate treatments. In the absence of glufosinate, four genes were differentially expressed in the transgenic lines and another 80 genes were differentially expressed in the presence of glufosinate, 29 of which were specific to transgenic plants. In contrast, the number of differentially expressed genes specific to wild‐type plants was 194 during the early response at 6 h of glufosinate treatment, and increased to 3711 during the late response at 48 h. Although the wild‐type plants undergo extensive transcriptional reprofiling in response to herbicide‐induced stress and, finally, plant death, the transgenic plants appear to activate other detoxification processes to offset the toxic effects of the residual herbicide or its derivatives. This study provides the first description of the pleiotropic effects of the bar gene and glufosinate on the plant transcriptome.