Effects of drought and N level on the interactions of the root hemiparasite Rhinanthus alectorolophus with a combination of three host species

Increasing nitrogen deposition and more frequent drought events are likely to change plant interactions in natural grasslands. Both factors may also influence the interactions between hemiparasitic plants, regarded as keystone species in many grasslands, and their host species. We grew a combination of three suitable hosts, a grass, a forb and a legume, with and without the hemiparasite Rhinanthus alectorolophus at three levels of nitrogen (N) and two levels of water availability in a factorial design. Biomass of the hemiparasite and host community increased with N level and was reduced by drought to a similar degree. Larger plants in fertilised pots started to wilt earlier, and the presence of a hemiparasite further increased drought sensitivity. The hemiparasite strongly reduced biomass of the host community and overall productivity, and affected the competitive balance among host plants because it particularly reduced biomass of the dominant grass. These effects were the opposite of those of high N. The hemiparasite increased the root mass fraction of the hosts at all levels of N and water availability, indicating that the effect of the hemiparasite on the hosts was mainly due to loss of belowground resources. Our results indicate that hemiparasites will not always respond more strongly to increased N availability and drought than autotrophic plants, and that hemiparasites can have similarly strong effects on grassland communities as soil fertility and drought. By preferentially attacking dominant species the hemiparasites might alleviate the negative effects of nutrient enrichment on grassland diversity.

Transgenerational plasticity in Silene vulgaris in response to three types of stress

The environment experienced by plants can influence the phenotype of their offspring. Such transgenerational plasticity can be adaptive when it results in higher fitness of the offspring under conditions correlated with those experienced by the mother plant. However, it has rarely been tested if such anticipatory parental effects may be induced with different environments. We grew clonal replicates of Silene vulgaris under control conditions and three types of stress (nutrient deficiency, copper addition and drought), which are known from natural populations of the species. We then subjected offspring from differently treated mother plants to each of the different stress treatments to analyse the influence of maternal and offspring environment on performance and several functional traits. Current stress treatments strongly influenced biomass and functional traits of the plants, mostly in line with responses predicted by the theory of functional equilibrium. Plant performance was also influenced by maternal stress treatments, and some effects independent of initial size differences remained until harvest. In particular, stressed mothers produced offspring of higher fitness than control plants. However, there was no evidence for treatment-specific adaptive transgenerational plasticity, as offspring from a mother plant that had grown in a specific environment did not grow better in that environment than other plants. Our results indicate that the maternal environment may affect offspring traits and performance, but also that this transgenerational plasticity is not necessarily adaptive.

Taxa distribution and RAPD markers indicate different origin and regional differentiation of hybrids in the invasive Fallopia complex in central-western Europe

Interspecific hybridization can be a driving force for evolutionary processes during plant invasions, by increasing genetic variation and creating novel gene combinations, thereby promoting genetic differentiation among populations of invasive species in the introduced range. We examined regional genetic structure in the invasive Fallopia complex, consisting of F. japonica var. japonica, F. sachalinensis and their hybrid F. x bohemica, in seven regions in Germany and Switzerland using RAPD analysis and flow cytometry. All individuals identified as F. japonica var. japonica had the same RAPD phenotype, while F. sachalinensis (11 RAPD phenotypes for 11 sampled individuals) and F. x bohemica (24 RAPD phenotypes for 32 sampled individuals) showed high genotypic diversity. Bayesian cluster analysis revealed three distinct genetic clusters. The majority of F. x bohemica individuals were assigned to a unique genetic cluster that differed from those of the parental species, while the other F. x bohemica individuals had different degrees of admixture to the three genetic clusters. At the regional scale, the occurrence of male-fertile F. sachalinensis coincided with the distribution of F. x bohemica plants showing a high percentage of assignment to both parental species, suggesting that they originated from hybridization between the parental species. In contrast, in regions where male-fertile F. sachalinensis were absent, F. x bohemica belonged to the non-admixed genetic group, indicating multiple introductions of hybrids or sexual reproduction among hybrids. We also found regional differentiation in the gene pool of F. x bohemica, with individuals within the same region more similar to each other than to individuals from different regions.

Reduced fecundity in small populations of the rare plant Gentianopsis ciliate (Gentianaceae)

Habitat destruction is the main cause for the biodiversity crisis. Surviving populations are often fragmented, i.e., small and isolated from each other. Reproduction of plants in small populations is often reduced, and this has been attributed to inbreeding depression, reduced attractiveness for pollinators, and reduced habitat quality in small populations. Here we present data on the effects of fragmentation on the rare, self-compatible perennial herb Gentianopsis ciliata (Gentianaceae), a species with very small and presumably well-dispersed seeds. We studied the relationship between population size, plant size, and the number of flowers produced in 63 populations from 1996-1998. In one of the years, leaf and flower size and the number of seeds produced per fruit was studied in a subset of 25 populations. Plant size, flower size, and the number of seeds per fruit and per plant increased with population size, whereas leaf length and the number of flowers per plant did not. The effects of population size on reproduction and on flower size remained significant if the effects were adjusted for differences in plant size, indicating that they could not be explained by differences in habitat quality. The strongly reduced reproduction in small populations may be due to pollination limitation, while the reduced flower size could indicate genetic effects.

Xylem water content and wood density in spruce and oak trees detected by high-resolution computed tomography

Elucidation of the mechanisms involved in long-distance water transport in trees requires knowledge of the water distribution within the sapwood and heartwood of the stem as well as of the earlywood and latewood of an annual ring. X-ray computed tomography is a powerful tool for measuring density distributions and water contents in the xylem with high spatial resolution. Ten- to 20-year-old spruce (Picea abies L. KARST.) and oak (Quercus robur) trees grown in the field were used throughout the experiments. Stem and branch discs were collected from different tree heights, immediately deep frozen, and used for the tomographic determinations of spatial water distributions. Results are presented for single-tree individuals, demonstrating heartwood and sapwood distribution throughout their entire length as well as the water relations in single annual rings of both types of wood. Tree rings of the sapwood show steep water gradients from latewood to earlywood, whereas those of the heartwood reflect water deficiency in both species. Although only the latest two annual rings of the ringporous species are generally assumed to transport water, we found similar amounts of water and no tyloses in all rings of the oak sapwood, which indicates that at least water storage is important in the whole sapwood.

RAPD variation in relation to population size and plant fitness in the rare Gentianella germanica (Gentianaceae)

We investigated the distribution of genetic variation and the relationship between population size and genetic variation in the rare plant Gentianella germanica using RAPD (random amplified polymorphic DNA) profiles. Plants for the analysis were grown from seeds sampled from 72 parent plants in 11 G. germanica populations of different size (40-5000 fruiting individuals). In large populations, seeds were sampled from parents in two spatially distinct subpopulations comparable in area to the total area covered by small populations. Analysis of molecular variance revealed significant genetic variation among populations (P <0.001), while genetic variation among subpopulations was marginally significant (P <0.06). Average molecular variance within subpopulations in large populations did not differ significantly from whole-population values. There was a positive correlation between genetic variation and population size (P <0.01). Genetic variation was also positively correlated with the number of seeds per plant in the field (P <0.02) and the number of flowers per planted seed in a common garden experiment (P <0.051). We conclude that gene flow among natural populations is very limited and that reduced plant fitness in small populations of G. germanica most likely has genetic causes. Management should aim to increase the size of small populations to minimize further loss of genetic variation. Because a large proportion of genetic variation is among populations, even small populations are worth preserving.

Mating structure and inbreeding and outbreeding depression in the rare plant Gentianella germanica (Gentianaceae)

Isolation and small size of populations as a result of habitat destruction and fragmentation may negatively affect plant fitness through pollinator limitation and increased levels of inbreeding. To increase genetic variation in small populations of rare plants artificial gene flow has been suggested as a management tool. We investigated whether pollinator limitation and inbreeding depression could reduce fitness in Gentianella germanica, an endangered biennial of increasingly fragmented calcareous grasslands in Central Europe. We experimentally excluded pollinators and generated progenies by hand-pollinating flowers with pollen from different distances. G. germanica was highly selfing. Pollinator exclusion strongly reduced seed set, indicating that pollinator limitation could potentially reduce plant fitness. Germination rate as well as number of leaves and rosette size of progeny from 10-m crosses was higher than that of progeny from open pollinations, self-, 1-m, and interpopulation crosses. After 6 mo of growth differences in the number of surviving plants persisted, whereas differences in plant size did not. The results suggest that inbreeding depression may reduce plant performance in G. germanica. Outbreeding depression in the performance of progeny from interpopulation crosses indicates that caution is necessary in using artificial interpopulation gene flow as a management tool.

A survey of pediatric critical care nurses' knowledge of pain management

BACKGROUND: Although nurses are accountable for pain management, it cannot be assumed that they are well informed about pain. Nurses' knowledge base underlies their pain management; therefore, it is important to measure their knowledge. OBJECTIVE: To measure pediatric critical care nurses' knowledge of pain management. METHOD: A descriptive, exploratory study was done. After a pilot study, an investigator-developed Pain Management Knowledge Test was distributed to 50 pediatric ICU nurses. Test responses were collected anonymously and coded by number. Item analysis was done, and descriptive statistics were calculated. Modified content analysis was used on requests for pain-related information. RESULTS: The test return rate was 38%. The overall mean score was 63%. Mean scores within test subsections varied from 50% to 92%. Other mean scores were 85% on a nine-item scale of drug-action items and 92% on a two-item scale of intervention items. However, no nurse recognized that cognitive-behavioral techniques can inhibit transmission of pain impulses; only 32% indicated that meperidine converts to a toxic metabolite, only 47% recognized nalbuphine as a drug that may cause signs and symptoms of withdrawal if given to a patient who has been receiving an opioid; and only 63% indicated that when a child states that the child has pain, pain exists. Thirteen nurses requested pain-related information, and all requests focused on analgesic medications. CONCLUSIONS: Testing nurses' knowledge of pain indicated gaps that can be addressed through educational interventions. Research is needed in which the test developed for this study is used as both pretest and posttest in an intervention study with pediatric critical care nurses or is modified for use with nurses in other clinical areas.

Isotope abundance ratios of sr in wine provenance determinations, in a tree-root activity study, and of pb in a pollution study on tree-rings

Abstract In this contribution, the various and fundamentally different uses and applications of isotope signatures (of both heavy and light elements) are discussed. Examples are given for the successful use of (87)Sr/(86)Sr in uncovering fraud in wine trade. Also, in an experiment related to "Waldsterben", (87)Sr/(86)Sr analyses reveal rather unexpected responses of spruces and maple-trees to mechanical damage of their roots. In another study, from (206)Pb/(207)Pb (and (208)Pb/(207)Pb) analyses of tree growth-rings it is demonstrated that they do not accurately record lead burdens in the environment. This is contrary to current views on the subject of tree-rings as reliable banks of past heavy metal pollutions of the biosphere. Furthermore, new perspectives of applications of isotopes in biological tissues, including those of cosmogenic and nucleogenic origin will be shortly outlined.

A survey of pediatric critical care nurses' knowledge of pain management

BACKGROUND

Although nurses are accountable for pain management, it cannot be assumed that they are well informed about pain. Nurses' knowledge base underlies their pain management; therefore, it is important to measure their knowledge.

OBJECTIVE

To measure pediatric critical care nurses' knowledge of pain management.

METHOD

A descriptive, exploratory study was done. After a pilot study, an investigator-developed Pain Management Knowledge Test was distributed to 50 pediatric ICU nurses. Test responses were collected anonymously and coded by number. Item analysis was done, and descriptive statistics were calculated. Modified content analysis was used on requests for pain-related information.

RESULTS

The test return rate was 38%. The overall mean score was 63%. Mean scores within test subsections varied from 50% to 92%. Other mean scores were 85% on a nine-item scale of drug-action items and 92% on a two-item scale of intervention items. However, no nurse recognized that cognitive-behavioral techniques can inhibit transmission of pain impulses; only 32% indicated that meperidine converts to a toxic metabolite, only 47% recognized nalbuphine as a drug that may cause signs and symptoms of withdrawal if given to a patient who has been receiving an opioid; and only 63% indicated that when a child states that the child has pain, pain exists. Thirteen nurses requested pain-related information, and all requests focused on analgesic medications.

CONCLUSIONS

Testing nurses' knowledge of pain indicated gaps that can be addressed through educational interventions. Research is needed in which the test developed for this study is used as both pretest and posttest in an intervention study with pediatric critical care nurses or is modified for use with nurses in other clinical areas.