bluuebunny/crossref_metadata_2025 huggingface dataset:
ELKS, a Protein Structurally Related to the Active Zone-associated Protein CAST, Is Expressed in Pancreatic β Cells and Functions in Insulin Exocytosis: Interaction of ELKS with Exocytotic Machinery Analyzed by Total Internal Reflection Fluorescence Microscopy
Authors: Ohara-Imaizumi Mica , Ohtsuka Toshihisa , Matsushima Satsuki , Akimoto Yoshihiro , Nishiwaki Chiyono , Nakamichi Yoko , Kikuta Toshiteru , Nagai Shintaro , Kawakami Hayato , Watanabe Takashi , Nagamatsu Shinya
Published: May 2005

The cytomatrix at the active zone (CAZ) has been implicated in defining the site of Ca2+-dependent exocytosis of neurotransmitters. Here, we demonstrate the expression and function of ELKS, a protein structurally related to the CAZ protein CAST, in insulin exocytosis. The results of confocal and immunoelectron microscopic analysis showed that ELKS is present in pancreatic β cells and is localized close to insulin granules docked on the plasma membrane-facing blood vessels. Total internal reflection fluorescence microscopy imaging in insulin-producing clonal cells revealed that the ELKS clusters are less dense and unevenly distributed than syntaxin 1 clusters, which are enriched in the plasma membrane. Most of the ELKS clusters were on the docking sites of insulin granules that were colocalized with syntaxin 1 clusters. Total internal reflection fluorescence images of single-granule motion showed that the fusion events of insulin granules mostly occurred on the ELKS cluster, where repeated fusion was sometimes observed. When the Bassoon-binding region of ELKS was introduced into the cells, the docking and fusion of insulin granules were markedly reduced. Moreover, attenuation of ELKS expression by small interfering RNA reduced the glucose-evoked insulin release. These data suggest that the CAZ-related protein ELKS functions in insulin exocytosis from pancreatic β cells.
Nuclear Import of TFIIB Is Mediated by Kap114p, a Karyopherin with Multiple Cargo-binding Domains
Authors: Hodges Jennifer L. , Leslie Jennifer H. , Mosammaparast Nima , Guo Yurong , Shabanowitz Jeffrey , Hunt Donald F. , Pemberton Lucy F.
Published: May 2005

Nuclear import and export is mediated by an evolutionarily conserved family of soluble transport factors, the karyopherins (referred to as importins and exportins). The yeast karyopherin Kap114p has previously been shown to import histones H2A and H2B, Nap1p, and a component of the preinitiation complex (PIC), TBP. Using a proteomic approach, we have identified several potentially new cargoes for Kap114p. These cargoes include another PIC component, the general transcription factor IIB or Sua7p, which interacted directly with Kap114p. Consistent with its role as a Sua7p import factor, deletion of KAP114 led to specific mislocalization of Sua7p to the cytoplasm. An interaction between Sua7p and TBP was also detected in cytosol, raising the possibility that both Sua7p and TBP can be coimported by Kap114p. We have also shown that Kap114p possesses multiple overlapping binding sites for its partners, Sua7p, Nap1p, and H2A and H2B, as well as RanGTP and nucleoporins. In addition, we have assembled an in vitro complex containing Sua7p, Nap1p, and histones H2A and H2B, suggesting that this Kap may import several proteins simultaneously. The import of more than one cargo at a time would increase the efficiency of each import cycle and may allow the regulation of coimported cargoes.
The Golgi-associated Protein GRASP65 Regulates Spindle Dynamics and Is Essential for Cell Division
Authors: Sütterlin Christine , Polishchuk Roman , Pecot Matt , Malhotra Vivek
Published: May 2005

At the onset of mitosis, the pericentriolar Golgi apparatus of mammalian cells is converted into small fragments, which are dispersed throughout the cytosol. The Golgi-associated protein GRASP65 is involved in this process. To address the role of GRASP65 in mitotic Golgi fragmentation, we depleted the protein from HeLa cells by RNAi. In the absence of GRASP65, the number of cisternae per Golgi stack is reduced without affecting the overall organization of Golgi membranes and protein transport. GRASP65-depleted cells entered mitosis, but accumulated in metaphase with condensed chromatin and multiple aberrant spindles and eventually died. Although Centrin2 and g-tubulin were detected in two of the spindle poles, the other spindle poles contained g-tubulin, but not Centrin2. Furthermore, we provide evidence that the expression of the C-terminus of GRASP65 interferes with entry of cells into mitosis. Our results suggest the requirement for GRASP65 in the regulation of spindle dynamics rather than a direct role in the stacking of Golgi cisternae. This novel function is in addition to the previously established negative role of GRASP65 at the G2/M transition, which is mediated by its C-terminus.
The Mitotic Cyclins Clb2p and Clb4p Affect Morphogenesis inCandida albicans
Authors: Bensen Eric S. , Clemente-Blanco Andres , Finley Kenneth R. , Correa-Bordes Jaime , Berman Judith
Published: May 2005

The ability of Candida albicans to switch cellular morphologies is crucial for its ability to cause infection. Because the cell cycle machinery participates in Saccharomyces cerevisiae filamentous growth, we characterized in detail the two C. albicans B-type cyclins, CLB2 and CLB4, to better understand the molecular mechanisms that underlie the C. albicans morphogenic switch. Both Clb2p and Clb4p levels are cell cycle regulated, peaking at G2/M and declining before mitotic exit. On hyphal induction, the accumulation of the G1 cyclin Cln1p was prolonged, whereas the accumulation of both Clb proteins was delayed when compared with yeast form cells, indicating that CLB2 and CLB4 are differentially regulated in the two morphologies and that the dynamics of cyclin appearance differs between yeast and hyphal forms of growth. Clb2p-depleted cells were inviable and arrested with hyper-elongated projections containing two nuclei, suggesting that Clb2p is not required for entry into mitosis. Unlike Clb2p-depleted cells, Clb4p-depleted cells were viable and formed constitutive pseudohyphae. Clb proteins lacking destruction box domains blocked cell cycle progression resulting in the formation of long projections, indicating that both Clb2p and Clb4p must be degraded before mitotic exit. In addition, overexpression of either B-type cyclin reduced the extent of filamentous growth. Taken together, these data indicate that Clb2p and Clb4p regulate C. albicans morphogenesis by negatively regulating polarized growth.
Spindle Pole Organization inDrosophilaS2 Cells by Dynein,Abnormal SpindleProtein (Asp), and KLP10A
Authors: Morales-Mulia Sandra , Scholey Jonathan M.
Published: May 2005

Dynein is a critical mitotic motor whose inhibition causes defects in spindle pole organization and separation, chromosome congression or segregation, and anaphase spindle elongation, but results differ in different systems. We evaluated the functions of the dynein–dynactin complex by using RNA interference (RNAi)-mediated depletion of distinct subunits in Drosophila S2 cells. We observed a striking detachment of centrosomes from spindles, an increase in spindle length, and a loss of spindle pole focus. RNAi depletion of Ncd, another minus-end motor, produced disorganized spindles consisting of multiple disconnected mini-spindles, a different phenotype consistent with distinct pathways of spindle pole organization. Two candidate dynein-dependent spindle pole organizers also were investigated. RNAi depletion of the abnormal spindle protein, Asp, which localizes to focused poles of control spindles, produced a severe loss of spindle pole focus, whereas depletion of the pole-associated microtubule depolymerase KLP10A increased spindle microtubule density. Depletion of either protein produced long spindles. After RNAi depletion of dynein–dynactin, we observed subtle but significant mislocalization of KLP10A and Asp, suggesting that dynein–dynactin, Asp, and KLP10A have complex interdependent functions in spindle pole focusing and centrosome attachment. These results extend recent findings from Xenopus extracts to Drosophila cultured cells and suggest that common pathways contribute to spindle pole organization and length determination.
Thirtieth Annual Congress on Veterinary Acupuncture: IVAS Report
Authors: Kaphle Krishna , Wu Ying-Ling , Lin Jen Hsou
Published: May 2005

More than 155 participants from 25 countries attended the 30th Annual IVAS Congress, September 8–11, 2004 in Oostende, Belgium. The focus was on veterinary acupuncture (AP) and immunology, and the event was sponsored by the International Veterinary Acupuncture Society (IVAS). IVAS is a non‐profit organization dedicated to promoting excellence in the practice of veterinary AP as an integral part of the total veterinary health care delivery system. The Society endeavors to establish uniformly high standards of veterinary AP through its educational programs and accreditation examination. IVAS seeks to integrate veterinary AP and the practice of Western veterinary science, while also noting that the science of veterinary AP does not overlook allied health systems, such as homeopathy, herbology, nutrition, chiropractic, kinesiology, etc. (www.ivas.org).
The Systemic Theory of Living Systems and Relevance to CAM: The Theory (Part II)
Authors: Olalde Rangel José A.
Published: May 2005

This theory stems from observing the universe′s ‘omniscient’ nature, manifested in flows of energy and information of its life plethora. A notorious example is the living cell′s intelligent nature, which guides its basic goal: to maximize survival. This last motivated me to address the living system′s intelligence, which constitutes a vital and controversial topic, its relationship with ‘incurable’ disease in general, including cancer, and to propose golden rules for therapeutics, as well as a definition of ideal medicine. The scientific confirmation of these findings is embedded in discoveries in cybernetics, biological theory of information and modern thermodynamic concepts, concerning energy and information exchange, within a living system. This approach′s practical application, denominated Systemic Medicine, has been substantiated by treatment and results obtained in >300 000 patients suffering from chronic degenerative diseases.
Auricular Acupuncture for Pain Relief after Ambulatory Knee Arthroscopy—A Pilot Study
Authors: Usichenko Taras I. , Hermsen Maria , Witstruck Torsten , Hofer Andre , Pavlovic Dragan , Lehmann Christian , Feyerherd Frank
Published: May 2005

Auricular acupuncture (AA) is effective in treating various pain conditions, but there have been no analyses of AA for the treatment of pain after ambulatory knee surgery. We assessed the range of analgesic requirements under AA after ambulatory knee arthroscopy. Twenty patients randomly received a true AA procedure (Lung, Shenmen and Knee points) or sham procedure (three non‐acupuncture points on the auricular helix) before ambulatory knee arthroscopy. Permanent press AA needles were retained in situ for one day after surgery. Post‐operative pain was treated with non‐steroidal anti‐inflammatory ibuprofen, and weak oral opioid tramadol was used for rescue analgesic medication. The quantity of post‐operative analgesics and pain intensity were used to assess the effect of AA. The incidence of analgesia‐related side effects, time to discharge from the anesthesia recovery room, heart rate and blood pressure were also recorded. Ibuprofen consumption after surgery in the AA group was lower than in the control group: median 500 versus 800 mg, P = 0.043. Pain intensity on a 100 mm visual analogue scale for pain measurement and other parameters were similar in both groups. Thus AA might be useful in reducing the post‐operative analgesic requirement after ambulatory knee arthroscopy.
Scalable Protocols Offer Efficient Design for Field Experiments
Authors: Nickerson David W.
Published: May 2005

Experiments conducted in the field allay concerns over external validity but are subject to the pitfalls of fieldwork. This article proves that scalable protocols conserve statistical efficiency in the face of problems implementing the treatment regime. Three designs are considered: randomly ordering the application of the treatment; matching subjects into groups prior to assignment; and placebo-controlled experiments. Three examples taken from voter mobilization field experiments demonstrate the utility of the design principles discussed.
Response to Coupé
Authors: Katz Ethan
Published: May 2005

I agree with the author's main point. Although I tried to fit a fixed-effects model to the simulated data, those data were generated from a model without fixed effects. In my experiment, therefore, use of the unconditional estimator was perfectly confounded with misspecification of the model. I thank the author for catching this flaw.
A quantitative test of the size efficiency hypothesis by means of a physiologically structured model
Authors: Hülsmann Stephan , Rinke Karsten , Mooij Wolf M.
Published: May 2005

According to the size‐efficiency hypothesis (SEH) larger bodied cladocerans are better competitors for food than small bodied species. In environments with fish, however, the higher losses of the large bodied species due to size‐selective predation may shift the balance in favor of the small bodied species. Here we present a theoretical framework for the analysis of the competitive abilities of zooplankton species that takes both competition and predation into account in one coherent analysis. By applying the conceptually well‐understood framework of physiologically structured population models we were able to predict the relative difference in predation rates necessary to cause a shift in dominance of the large‐bodied species (Daphnia pulicaria) to the small‐bodied species (D. galeata). These predictions depend only on seven easily interpretable parameters per species: size at birth, size at maturity and maximum size, age at maturity, maximal clutch size, egg development time and finally the half‐saturation constant for food. The critical equilibrium mortality of D. pulicaria was 0.16 d−1 at food concentrations close to the critical food concentration of D. galeata, i.e. D. pulicaria will win the competition as long as its mortality rate is below 0.16 d−1. At higher food concentrations the differential mortality curve (plotting equilibrium mortalities of both species against each other) approached a linear function with a slope of one and an intercept equal to the difference in maximal population birth rates. The prediction of critical predation rates was independent of the ingestion rate of the cladocerans and the algal carrying capacity and food regeneration rate of the environment although the mechanism works through competition for a shared algal food resource. We interpret these findings in terms of the relative predation risk large and small‐bodied cladocerans will face in various freshwater ecosystems.
Stability of pitcher‐plant microfaunal populations depends on food web structure
Authors: Trzcinski M. Kurtis , Walde Sandra J. , Taylor Philip D.
Published: May 2005

Enrichment (increasing K) destabilizes simple consumer–resource interactions, but increasing food web complexity in various ways can remove this paradox of enrichment. We varied resources and number of omnivorous predators (mosquitoes) and tested for effects on the stability (persistence and temporal variability) of microfaunal populations living in pitcher plants. Top‐down (omnivorous) effects were destabilizing, decreasing the persistence time of a rotifer, Habrotrocha rosa, and perhaps a microflagellate, Bodo sp. Enrichment effects were more complex, in part due to effects of shredding midges on resource availability, and in part due to interactions with predation. The persistence of Bodo increased with resource availability (more bacteria due to shredding by midges; no paradox of enrichment). Increasing resources by adding ants decreased persistence of H. rosa when mosquitoes were rare (paradox of enrichment), but the effect was reversed in leaves with significant colonization by mosquitoes. Thus, in the microfaunal community of pitcher plants, omnivorous predation tends to be destabilizing, and also tends to remove the paradox of enrichment.
Body size affects the spatial scale of habitat–beetle interactions
Authors: Holland Jeffrey D. , Fahrig Lenore , Cappuccino Naomi
Published: May 2005

We used abundance data and the program Focus to determine the spatial scale at which 31 species of longhorned beetles (Coleoptera: Cerambycidae) respond to forest habitat amount. We predicted that the spatial scale at which species respond would increase with body size, and that species using ephemeral larval habitat would respond at larger spatial scales than species using more stable larval habitat. We found that forest cover was a better measure of the amount of habitat for polyphagous species than for oligophagous species. Larger species of longhorned beetles responded to forest cover at larger scales. We did not find evidence that species using more ephemeral larval habitat conditions responded at larger scales than species developing in more stable habitat conditions. Our results highlight the importance of accurately describing habitat in studies of species–environment relationships. While scales of response may be species‐specific, some generalizations across species are possible.
Interactions between maternal effects and dispersal
Authors: Fowler Mike S.
Published: May 2005

Maternal effects and spatial processes are rightly recognised as being of great importance in the life histories of a number of different organisms. Previously, little effort has been made for investigating the potential for changes to arise from interactions between these two crucial processes. Here I tested the outcome of introducing a maternal effect on a population of dispersing organisms in different ways, under both spatially homogeneous and heterogeneous conditions, through novel modification of a well‐known population model. First, I proposed that parents contribute a proportion of offspring based on their own developmental experience. This is applied to dispersing organisms as well as those that remain in their natal patch to breed. I go on to ask how the density of dispersing offspring might be influenced by a maternal effect. What happens if parents that developed under relatively good (or bad) conditions compared to current conditions invest in dispersing offspring? This relaxes the assumption that populations have perfect knowledge of the local carrying capacity. The results highlight an interesting range of outcomes. By introducing a maternal effect into the potential future reproductive output otherwise highly unstable population dynamics were simplified (but not stabilised). If maternal effects affect dispersal decisions, it is possible for regular cycles with a period consistent with many examples from ecological time‐series’ to arise. These results are in agreement with previous studies, however, by investigating the effects in different aspects of life history, it is possible to predict the direction of the impact on population dynamics. This work also highlights the potential for regular cycles in population dynamics to arise due to maternal effects, in agreement with recent field studies.
Gap percolation in rainforests
Authors: Solé Ricard V. , Bartumeus Frederic , Gamarra Javier G. P.
Published: May 2005

Rainforests biodiversity is sustained by the three‐dimensional structure of their canopy which provides a wide range of physical microenvironments. Given the dynamic nature of the forest, the recognition of stable vertical layers or strata in the canopy is controversial. The spatial characterisation of potential habitats of understory species is not straightforward due to the complex structure of rainforest canopies and the wide ecological variability to which rainforest species can be adapted. Here we present a new description of potential understory habitats that give rise to a well‐defined characteristic vertical scale of forest organization hc≈13 m. Species living in microenvironments occurring at canopy heights below this critical height hccan only experience landscapes with disconnected habitat patches (i.e. fragmented habitat landscapes), while those species capable of living also above hcwill experience a fully connected landscape of suitable microenvironmental conditions. The possible implications for plant dispersal and animal colonisation strategies living at the understory or close‐to‐floor are discussed in relation to rainforest gap‐dynamics, habitat loss and habitat fragmentation processes. Long‐range and directed dispersal strategies (e.g. plant seed dispersal by animals) are optimal for those species living below hc, providing the best exploration of scarce habitats and a major robustness to habitat changes. On the other hand, dispersal strategies of those species capable to exploit habitats above hcneed not to be based on directed long‐range mechanisms. Different dispersal strategies may in turn imply different sensitiveness of species to habitat loss and habitat fragmentation processes in the rainforest.
Layering, the effective density of mussels and mass‐density boundary curves
Authors: Guiñez R.
Published: May 2005

Overall intraspecific mass‐density patterns have seldom been explored in animals. Instead, self‐thinning studies have predominated. The analysis of 253 samples in a multilayered mussel showed that the classical approach is biased by layering or crowding effects, suggesting a transition zone between density independence and self‐thinning, without a C–D effect. However, when the effective density (density corrected by layer effect) is used, space/allometric constraint expectations are met. Layering and crowding effects on self‐thinning and the mass‐density boundary should be common in mussels and other taxa showing aggregated distributions.
Community response to removals of plant functional groups and species from a Chihuahuan Desert shrubland
Authors: Buonopane Michelle , Huenneke Laura Foster , Remmenga Marta
Published: May 2005

Arid and semi‐arid ecosystems often exhibit diverse plant growth forms in water‐limited environments, but it is unclear whether resource competition (interference) is actually important in structuring communities. We chose a diverse Chihuahuan desert shrubland to examine the response of the plant community to experimental removals of selected perennial plant species or groups of species. Four treatments involved the removal of all individuals of all species of a single functional group (functional group removals: shrub removal, succulent removal, subshrub removal, perennial grass removal). Three other treatments involved removing species within functional groups. These seven treatments plus a control (no plants removed) were replicated six times each in 25×25 m experimental plots, in summer 1995. Permanent belt transects were surveyed for number and sizes of all vascular plants in spring and fall in 1997, 1999, 2000, and 2001. Those plots from which the dominant shrub, Larrea tridentata, was removed had not recovered in total plant cover or volume by 2001, but cover and volume in all other treatments were similar to those in control plots. Relatively few species demonstrated a positive response to the removal of other species or functional groups. The perennial grass group and forbs were the most responsive; perennial grass cover increased in the shrub removal treatment relative to the control but treatment differences diminished after dry growing seasons in 2000 and 2001. Results over the first five years suggest that either environmental conditions or intrinsic biological characteristics limit the ability of most plant species to respond to the removal of substantial fractions of community biomass and composition in the short term. Such slow response by both dominant and less abundant components of the community has implications for the recovery of semi‐arid systems after human disturbance or other events leading to the reduction of biological diversity.
Partitioning direct and indirect human‐induced effects on carbon sequestration of managed coniferous forests using model simulations and forest inventories
Authors: Vetter Mona , Wirth Christian , Böttcher Hannes , Churkina Galina , Schulze Ernst‐Detlef , Wutzler Thomas , Weber Georg
Published: May 2005

Temperate forest ecosystems have recently been identified as an important net sink in the global carbon budget. The factors responsible for the strength of the sinks and their permanence, however, are less evident. In this paper, we quantify the present carbon sequestration in Thuringian managed coniferous forests. We quantify the effects of indirect human‐induced environmental changes (increasing temperature, increasing atmospheric CO2 concentration and nitrogen fertilization), during the last century using BIOME‐BGC, as well as the legacy effect of the current age‐class distribution (forest inventories and BIOME‐BGC). We focused on coniferous forests because these forests represent a large area of central European forests and detailed forest inventories were available.

The model indicates that environmental changes induced an increase in biomass C accumulation for all age classes during the last 20 years (1982–2001). Young and old stands had the highest changes in the biomass C accumulation during this period. During the last century mature stands (older than 80 years) turned from being almost carbon neutral to carbon sinks. In high elevations nitrogen deposition explained most of the increase of net ecosystem production (NEP) of forests. CO2 fertilization was the main factor increasing NEP of forests in the middle and low elevations.

According to the model, at present, total biomass C accumulation in coniferous forests of Thuringia was estimated at 1.51 t C ha−1 yr−1 with an averaged annual NEP of 1.42 t C ha−1 yr−1 and total net biome production of 1.03 t C ha−1 yr−1 (accounting for harvest). The annual averaged biomass carbon balance (BCB: biomass accumulation rate‐harvest) was 1.12 t C ha−1 yr−1 (not including soil respiration), and was close to BCB from forest inventories (1.15 t C ha−1 yr−1). Indirect human impact resulted in 33% increase in modeled biomass carbon accumulation in coniferous forests in Thuringia during the last century. From the forest inventory data we estimated the legacy effect of the age‐class distribution to account for 17% of the inventory‐based sink. Isolating the environmental change effects showed that these effects can be large in a long‐term, managed conifer forest.
Structural characteristics and chemical composition of birch (Betula pendula) leaves are modified by increasing CO2 and ozone
Authors: Oksanen Elina , Riikonen Johanna , Kaakinen Seija , Holopainen Toini , Vapaavuori Elina
Published: May 2005

Impacts of ozone and CO2 enrichment, alone and in combination, on leaf anatomical and ultrastructural characteristics, nutrient status and cell wall chemistry in two European silver birch (Betula pendula Roth) clones were studied. The young soil‐growing trees were exposed in open‐top chambers over three growing seasons to 2 × ambient CO2 and/or ozone concentrations in central Finland. The trees were measured for changes in altogether 35 variables of leaf structure, nutrients and cell wall chemistry of green leaves, and 20 of the measured variables were affected by CO2 and/or O3. Elevated CO2 increased the size of chloroplasts and starch grains, number of mitochondria, P : N ratio, and contents of cell wall hemicellulose. Elevated CO2 decreased the total leaf thickness, specific leaf area, concentrations of N, K, Cu, S and Fe, and contents of cell wall α‐cellulose, uronic acids, acid‐soluble lignin and acetone‐soluble extractives. Elevated ozone led to thinner leaves, higher palisade to spongy ratio, increased number of peroxisomes and mitochondria, reduced content of Mn, Zn, Cu, hemicellulose and uronic acids, and lower Mn : N and Zn : N ratios. In the combined exposure, interactions were antagonistic. Ultrastructural changes became more evident towards the end of the exposure. Young leaves were tolerant against ozone‐caused oxidative stress, whereas oxidative H2O2 accumulation was found in older leaves. CO2 enrichment improved ozone tolerance not only through increased photosynthesis rates, but also through changes in cell wall chemistry (hemicellulose, in particular). However, nutrient imbalances due to ozone and/or CO2 may predispose the trees to other biotic and abiotic stresses. Down‐regulation and up‐regulation of photosynthesis under elevated CO2 through anatomical changes is discussed.
Analysing temperature response of decomposition of organic matter
Authors: Hyvönen Riitta , Ågren Göran I. , Dalias Panagiotis
Published: May 2005

In order to analyse temperature effects on decomposition of organic matter, we tested the following hypothesis: Can an Arrhenius type of equation with constant parameter values for the temperature response of decomposer growth rate adequately describe decomposition of organic matter or must some additional properties be made functions of temperature? Possible temperature effects were analysed by aggregating data in different ways from an experiment with 14C‐labelled wheat material incubated in the laboratory at different temperatures and with soil materials collected from seven coniferous forest stands in Europe. Our analysis shows that it is possible to let all the temperature dependence reside in the decomposer growth rate. The analysis also supports the use of an Arrhenius type of equation for the temperature response of decomposer growth rate but with the parameters specific for each soil, or at least a distinction between organic and mineral horizons seems necessary.
Net ecosystem CO2 exchange in Mojave Desert shrublands during the eighth year of exposure to elevated CO2
Authors: Jasoni Richard L. , Smith Stanley D. , Arnone John A.
Published: May 2005

Arid ecosystems, which occupy about 35% of the Earth's terrestrial surface area, are believed to be among the most responsive to elevated [CO2]. Net ecosystem CO2 exchange (NEE) was measured in the eighth year of CO2 enrichment at the Nevada Desert Free‐Air CO2 Enrichment (FACE) Facility between the months of December 2003–December 2004. On most dates mean daily NEE (24 h) (μmol CO2 m−2 s−1) of ecosystems exposed to elevated atmospheric CO2 were similar to those maintained at current ambient CO2 levels. However, on sampling dates following rains, mean daily NEEs of ecosystems exposed to elevated [CO2] averaged 23 to 56% lower than mean daily NEEs of ecosystems maintained at ambient [CO2]. Mean daily NEE varied seasonally across both CO2 treatments, increasing from about 0.1 μmol CO2 m−2 s−1 in December to a maximum of 0.5–0.6 μmol CO2 m−2 s−1 in early spring. Maximum NEE in ecosystems exposed to elevated CO2 occurred 1 month earlier than it did in ecosystems exposed to ambient CO2, with declines in both treatments to lowest seasonal levels by early October (0.09±0.03 μmol CO2 m−2 s−1), but then increasing to near peak levels in late October (0.36±0.08 μmol CO2 m−2 s−1), November (0.28±0.03 μmol CO2 m−2 s−1), and December (0.54±0.06 μmol CO2 m−2 s−1). Seasonal patterns of mean daily NEE primarily resulted from larger seasonal fluctuations in rates of daytime net ecosystem CO2 uptake which were closely tied to plant community phenology and precipitation. Photosynthesis in the autotrophic crust community (lichens, mosses, and free‐living cyanobacteria) following rains were probably responsible for the high NEEs observed in January, February, and late October 2004 when vascular plant photosynthesis was low. Both CO2 treatments were net CO2 sinks in 2004, but exposure to elevated CO2 reduced CO2 sink strength by 30% (positive net ecosystem productivity=127±17 g C m−2 yr−1 ambient CO2 and 90±11 g C m−2 yr−1 elevated CO2, P=0.011). This level of net C uptake rivals or exceeds levels observed in some forested and grassland ecosystems. Thus, the decrease in C sequestration seen in our study under elevated CO2– along with the extensive coverage of arid and semi‐arid ecosystems globally – points to a significant drop in global C sequestration potential in the next several decades because of responses of heretofore overlooked dryland ecosystems.
Land surface phenology and temperature variation in the International Geosphere–Biosphere Program high‐latitude transects
Authors: De Beurs Kirsten M. , Henebry Geoffrey M.
Published: May 2005

The International Geosphere–Biosphere Program has delineated five study areas that form a northern high‐latitude network for the analyses of vegetation and carbon dynamics. We examined the magnitude and significance of changes in the land surface phenologies of ecoregions within these transects using the NASA Pathfinder Advanced Very High‐Resolution Radiometer Land dataset. We applied the seasonal Mann–Kendall (SMK) trend test, a robust and nonparametric approach, to determine the significance of trends in the normalized difference vegetation index (NDVI) over the five transects. The SMK trend test provides an important alternative over the frequently used but unreliable trend analysis based on linear regression.

In addition, we modeled the land surface phenology using quadratic or nonlinear spherical models to relate the NDVI data to accumulated growing degree‐days (base 0°C). Nonlinear spherical models parsimoniously describe the green‐up dynamics in taiga and tundra ecoregions. Models for each ecoregion within each transect were fitted separately for two time periods (1985–1988 and 1995–1999) and their parameter coefficient estimates were compared. In 10 of 24 ecoregions that comprise 72% of the land area in the transects, the date of the peak NDVI value was significantly earlier (range 2–18 days) in the second study period than in the first study period. This progression was more pronounced in North America than in Siberia (weighted average of 9.3 vs. 6.3 days earlier).

Understanding of what constitutes significant change in land surface phenology amidst background variation is a critical component of global change science. A diversity of datasets, techniques, and study areas has led to a range of conclusions about boreal phenology. We discuss statistical pitfalls in standard analyses and offer a framework to conduct statistically reliable change assessments of land surface phenologies.
Losses of soil organic carbon under wind erosion in China
Authors: Yan Hao , Wang Shaoqiang , Wang Changyao , Zhang Guoping , Patel Nilanchal
Published: May 2005

Soil organic carbon (SOC) storage generally represents the long‐term net balance of photosynthesis and total respiration in terrestrial ecosystems. However, soil erosion can affect SOC content by direct removal of soil and reduction of the surface soil depth; it also affects plant growth and soil biological activity, soil air CO2 concentration, water regimes, soil temperature, soil respiration, carbon flux to the atmosphere, and carbon deposition in soil. In arid and semi‐arid region of northern China, wind erosion caused soil degradation and desert expansion. This paper estimated the SOC loss of the surface horizon at eroded regions based on soil property and wind erosion intensity data. The SOC loss in China because of wind erosion was about 75 Tg C yr−1 in 1990s. The spatial pattern of SOC loss indicates that SOC loss of the surface horizon increases significantly with the increase of soil wind erosion intensity. The comparison of SOC loss and annual net primary productivity (NPP) of terrestrial ecosystem was discussed in wind erosion regions of China. We found that NPP is also low in the eroded regions and heavy SOC loss often occurs in regions where NPP is very small. However, there is potential to improve our study to resolve uncertainty on the soil organic matter oxidation and soil deposition processes in eroded and deposited sites.
Long‐term potential ecosystem responses to greenhouse gas‐induced thermohaline circulation collapse
Authors: Higgins Paul A. T. , Schneider Stephen H.
Published: May 2005

Abrupt climate change, such as could occur with significant thermohaline circulation (THC) weakening, appears throughout the palaeoclimate record and in many model experiments. We examine potential responses of ecosystem structure and function to the combined influence of THC collapse and greenhouse gas increase in Central England using a broad range of temperature scenarios. We demonstrate that biological communities in the North Atlantic region could be heavily influenced by THC collapse, but that the pattern of ecosystem responses depends upon the seasonal pattern of temperature changes. Plausible THC collapse scenarios threaten the remnant habitat fragments, upon which much of England's remaining biodiversity depends, by causing shifts away from the currently dominant temperate broadleaf cold deciduous tree type. Furthermore, some ecosystem responses, particularly of energy partitioning between sensible and latent heat fluxes, constitute potentially substantial feedbacks to the local climate system. However, accurate assessment of biotic responses to THC collapse requires far better confidence of the resulting seasonal temperature cycle than climate models currently provide.
The language of ‘experience’ in nursing research
Authors: Allen David , Cloyes Kristin
Published: May 2005

The language of ‘experience’ in nursing research

This paper is an analysis of how the signifier ‘experience’ is used in nursing research. We identify a set of issues we believe accompany the use of experience but are rarely addressed. These issues are embedded in a spectrum that includes ontological commitments, visions of the person/self and its relation to ‘society’, understandings of research methodology and the politics of nursing. We argue that a poststructuralist understanding of the language of experience in research opens up additional ways to analyze the relationship between the conduct of nursing research and cultural/political commitments.
Modes of rationality in nursing documentation: biology, biography and the ‘voice of nursing’
Authors: Hyde Abbey , Treacy Margaret (P) , Scott P. Anne , Butler Michelle , Drennan Jonathan , Irving Kate , Byrne Anne , MacNeela Padraig , Hanrahan Marian
Published: May 2005

Modes of rationality in nursing documentation: biology, biography, and the ‘voice of nursing’

This article is based on a discourse analysis of the complete nursing records of 45 patients, and concerns the modes of rationality that mediated text‐based accounts relating to patient care that nurses recorded. The analysis draws on the work of the critical theorist, Jürgen Habermas, who conceptualised rationality in the context of modernity according to two types: purposive rationality based on an instrumental logic, and value rationality based on ethical considerations and moral reasoning. Our analysis revealed that purposive rationality dominated the content of nursing documentation, as evidenced by a particularly bio‐centric and modernist construction of the workings of the body within the texts. There was little reference in the documentation to central themes of contemporary nursing discourses, such as notions of partnership, autonomy, and self‐determination, which are associated with value rationality. Drawing on Habermas, we argue that this nursing documentation depicted the colonisation of the sociocultural lifeworld by the bio‐technocratic system. Where nurses recorded disagreements that patients had with medical regimes, the central struggle inherent in the project of modernity became transparent — the tension between the rational and instrumental control of people through scientific regulation and the autonomy of the subject. The article concludes by problematising communicative action within the context of nursing practice.
Nursing practice as bricoleur activity: a concept explored
Authors: Gobbi Mary
Published: May 2005

Nursing practice as bricoleur activity: a concept explored

The debates concerning the nature of nursing practice are often rooted in tensions between artistic, scientific and magical/mythical practice. It is within this context that the case is argued for considering that nursing practice involves bricoleur activity. This stance, which is derived from the work of Levi‐Strauss, conceives elements of nursing practice as an embodied, bricoleur practice where practitioners draw on the ‘shards and fragments’ of the situation‐at‐hand to resolve the needs of the individual patient for whom they care. This conceptualisation of nursing practice will be analysed with a particular emphasis on its implication for nursing epistemology, pedagogy and praxis. The evidence to support this argument is drawn from empirical work that investigated nurses’ use of intuition, the work of Levi‐Strauss, and issues in nursing epistemology and ontology. The paper itself is written from the perspective of a bricoleur who uses ‘bits and pieces’ from the domains of nursing, philosophy, psychology, education, sociology and anthropology.
Phenomenology as rhetoric
Authors: Paley John
Published: May 2005

Phenomenology as rhetoric

The literature on ‘nursing phenomenology’ is driven by a range of ontological and epistemological considerations, intended to distance it from conventionally scientific approaches. However, this paper examines a series of discrepancies between phenomenological rhetoric and phenomenological practice. The rhetoric celebrates perceptions and experience; but the concluding moment of a research report almost always makes implicit claims about reality. The rhetoric insists on uniquely personal meanings; but the practice offers blank, anonymous abstractions. The rhetoric invites us to believe that knowing is subjective and involved, but at the same time it recommends a technique (bracketing) which can only represent a crude, and entirely misconceived, gesture towards objectivity. Finally, the rhetoric claims that generalisation is beside the point; but the majority of researchers generalise anyway. In quietly ignoring their own rhetoric, ‘phenomenologists’ appropriate scientific prerogatives illegitimately. For their methods do not entitle them to lay claim to anything resembling ‘objectivity’, or generalisability, or ‘reality’, or theoretical abstraction. Like other researchers, they want to talk in generalisable terms about reality; they want to be objective, they want to do theory. But they are saddled with a philosophy that is disabling, because it says they can only talk about perceptions, and meanings, and uniqueness.
Taking account of local culture: limits to the development of a professional ethos
Authors: Goopy Suzanne E.
Published: May 2005

Taking account of local culture: limits to the development of a professional ethos

The need to extend the discussion of culture in the study of nursing, combined with an enthusiasm for the possibility of viewing nursing from a new perspective, provides the impetus for this study. Based on fieldwork undertaken in the intensive care unit (RICU) of a major public hospital in Rome (Italy), this paper explores some of the key aspects of the social relations and local staff culture of one particular group of Italian nurses. In a climate of globalization, where the deployment of dominant Anglo‐American ideas is difficult to counter, the RICU presents as a setting which challenges the widespread assumptions of universal standards of nursing practice. By building a picture of the working world of these particular nurses, we are assisted in our understanding of nursing practice as a local cultural activity. In exploring the significance of local culture this paper brings into question the universality of the current paradigm of professionalism and professional identity, and emphasizes the value of acknowledging local culture.
Evidence for in situ crude oil biodegradation after the Prestige oil spill
Authors: Medina‐Bellver Javier I. , Marín Patricia , Delgado Antonio , Rodríguez‐Sánchez Alicia , Reyes Emilio , Ramos Juan L. , Marqués Silvia
Published: May 2005

In November 2002, the oil tanker Prestige sank off the Spanish coast after releasing approximately 17 000 tones of heavy fuel, coating several hundred kilometres of coastline in oil sludge. In December 2002 and February 2003, samples were collected from the shore of the Galician coast to analyse the indigenous population ability to carry out crude oil degradation in situ. Carbon isotopic ratio of the dissolved inorganic carbon (DIC) in seawater samples was used as a rapid method to directly assess activity of microbes on the oil components. 12CO2/13CO2 ratio in samples from certain locations along the coast revealed degradation of a very δ13C‐negative source such as the Prestige crude oil (−30.6‰). Putative biodegradation processes taking place at areas with high income of fresh seawater could not be detected with this technique. Laboratory‐scale biostimulation processes carried out in samples with the highest oil biodegradation activity showed that N/P deficiency in seawater is a limiting factor for crude oil degradation. The most probable number (MPN) of crude oil component degraders was estimated for several aromatic compounds (naphthalene, anthracene, phenanthrene, pyrene) and for undecane. Our results clearly show that bacteria present in the contaminated water are readily able to transform components of the crude oil into inorganic carbon.
Impact of lime, nitrogen and plant species on fungal community structure in grassland microcosms
Authors: Kennedy Nabla , Connolly John , Clipson Nicholas
Published: May 2005

A microcosm‐based approach was used to study impacts of plant and chemical factors on the fungal community structure of an upland acidic grassland soil. Seven plant species typical of both unimproved and fertilized grasslands were either left unamended or treated with lime, nitrogen or lime plus nitrogen. Fungal community structure was assessed by a molecular approach, fungal automated ribosomal intergenic spacer analysis (FARISA), while fungal biomass was estimated by measuring soil ergosterol content. Addition of nitrogen (with or without lime) had the largest effect, decreasing soil pH, fungal biomass and fungal ribotype number, but there was little corresponding change in fungal community structure. Although different plant species were associated with some changes in fungal biomass, this did not result in significant differences in fungal community structure between plant species. Addition of lime alone caused no changes in fungal biomass, ribotype number or community structure. Overall, fungal community structure appeared to be more significantly affected through interactions between plant species and chemical treatments, as opposed to being directly affected by changes in individual improvement factors. These results were in contrast to those found for the bacterial communities of the same soils, which changed substantially in response to chemical (lime and nitrogen) additions.