bluuebunny/crossref_metadata_2025 huggingface dataset:
Ecosystem feedbacks and cascade processes: understanding their role in the responses of Arctic and alpine ecosystems to environmental change
Authors: WOOKEY PHILIP A. , AERTS RIEN , BARDGETT RICHARD D. , BAPTIST FLORENCE , BRÅTHEN KARI ANNE , CORNELISSEN JOHANNES H. C. , GOUGH LAURA , HARTLEY IAIN P. , HOPKINS DAVID W. , LAVOREL SANDRA , SHAVER GAIUS R.
Published: November 2008

Global environmental change, related to climate change and the deposition of airborne N‐containing contaminants, has already resulted in shifts in plant community composition among plant functional types in Arctic and temperate alpine regions. In this paper, we review how key ecosystem processes will be altered by these transformations, the complex biological cascades and feedbacks that might result, and some of the potential broader consequences for the earth system. Firstly, we consider how patterns of growth and allocation, and nutrient uptake, will be altered by the shifts in plant dominance. The ways in which these changes may disproportionately affect the consumer communities, and rates of decomposition, are then discussed. We show that the occurrence of a broad spectrum of plant growth forms in these regions (from cryptogams to deciduous and evergreen dwarf shrubs, graminoids and forbs), together with hypothesized low functional redundancy, will mean that shifts in plant dominance result in a complex series of biotic cascades, couplings and feedbacks which are supplemental to the direct responses of ecosystem components to the primary global change drivers. The nature of these complex interactions is highlighted using the example of the climate‐driven increase in shrub cover in low‐Arctic tundra, and the contrasting transformations in plant functional composition in mid‐latitude alpine systems. Finally, the potential effects of the transformations on ecosystem properties and processes that link with the earth system are reviewed. We conclude that the effects of global change on these ecosystems, and potential climate‐change feedbacks, cannot be predicted from simple empirical relationships between processes and driving variables. Rather, the effects of changes in species distributions and dominances on key ecosystem processes and properties must also be considered, based upon best estimates of the trajectories of key transformations, their magnitude and rates of change.
Response of isoprene emission to ambient CO2 changes and implications for global budgets
Authors: HEALD COLETTE L. , WILKINSON MICHAEL J. , MONSON RUSSELL K. , ALO CLEMENT A. , WANG GUILING , GUENTHER ALEX
Published: November 2008

We explore the potential role of atmospheric carbon dioxide (CO2) on isoprene emissions using a global coupled land–atmosphere model [Community Atmospheric Model–Community Land Model (CAM–CLM)] for recent (year 2000, 365 ppm CO2) and future (year 2100, 717 ppm CO2) conditions. We incorporate an empirical model of observed isoprene emissions response to both ambient CO2 concentrations in the long‐term growth environment and short‐term changes in intercellular CO2 concentrations into the MEGAN biogenic emission model embedded within the CLM. Accounting for CO2 inhibition has little impact on predictions of present‐day global isoprene emission (increase from 508 to 523 Tg C yr−1). However, the large increases in future isoprene emissions typically predicted in models, which are due to a projected warmer climate, are entirely offset by including the CO2 effects. Projected global isoprene emissions in 2100 drop from 696 to 479 Tg C yr−1 when this effect is included, maintaining future isoprene sources at levels similar to present day. The isoprene emission response to CO2 is dominated by the long‐term growth environment effect, with modulations of 10% or less due to the variability in intercellular CO2 concentration. As a result, perturbations to isoprene emissions associated with changes in ambient CO2 are largely aseasonal, with little diurnal variability. Future isoprene emissions increase by more than a factor of two in 2100 (to 1242 Tg C yr−1) when projected changes in vegetation distribution and leaf area density are included. Changing land cover and the role of nutrient limitation on CO2 fertilization therefore remain the largest source of uncertainty in isoprene emission prediction. Although future projections suggest a compensatory balance between the effects of temperature and CO2 on isoprene emission, the enhancement of isoprene emission due to lower ambient CO2 concentrations did not compensate for the effect of cooler temperatures over the last 400 thousand years of the geologic record (including the Last Glacial Maximum).
Leaf isoprene emission rate as a function of atmospheric CO2 concentration
Authors: WILKINSON MICHAEL J. , MONSON RUSSELL K. , TRAHAN NICOLE , LEE STANFIELD , BROWN ERIN , JACKSON ROBERT B. , POLLEY H. WAYNE , FAY PHILIP A. , FALL RAY
Published: November 2008

There is considerable interest in modeling isoprene emissions from terrestrial vegetation, because these emissions exert a principal control over the oxidative capacity of the troposphere. We used a unique field experiment that employs a continuous gradient in CO2 concentration from 240 to 520 ppmv to demonstrate that isoprene emissions in Eucalyptus globulus were enhanced at the lowest CO2 concentration, which was similar to the estimated CO2 concentrations during the last Glacial Maximum, compared with 380 ppmv, the current CO2 concentration. Leaves of Liquidambar styraciflua did not show an increase in isoprene emission at the lowest CO2 concentration. However, isoprene emission rates from both species were lower for trees grown at 520 ppmv CO2 compared with trees grown at 380 ppmv CO2. When grown in environmentally controlled chambers, trees of Populus deltoides and Populus tremuloides exhibited a 30–40% reduction in isoprene emission rate when grown at 800 ppmv CO2, compared with 400 ppmv CO2. P. tremuloides exhibited a 33% reduction when grown at 1200 ppmv CO2, compared with 600 ppmv CO2. We used current models of leaf isoprene emission to demonstrate that significant errors occur if the CO2 inhibition of isoprene is not taken into account. In order to alleviate these errors, we present a new model of isoprene emission that describes its response to changes in atmospheric CO2 concentration. The model logic is based on assumed competition between cytosolic and chloroplastic processes for pyruvate, one of the principal substrates of isoprene biosynthesis.
Keeping up with early springs: rapid range expansion in an avian herbivore incurs a mismatch between reproductive timing and food supply
Authors: VAN DER JEUGD HENK P. , EICHHORN GÖTZ , LITVIN KONSTANTIN E. , STAHL JULIA , LARSSON KJELL , VAN DER GRAAF ALEXANDRA J. , DRENT RUDI H.
Published: November 2008

Within three decades, the barnacle goose population wintering on the European mainland has dramatically increased in numbers and extended its breeding range. The expansion has occurred both within the Arctic as well as by the colonization of temperate areas. Studies of performance of individuals in expanding populations provide information on how well species can adapt to novel environments and global warming. We, therefore, studied the availability of high quality food as well as timing of reproduction, wing moult, fledgling production and postfledging survival of individually marked geese in three recently established populations: one Arctic (Barents Sea) and two temperate (Baltic, North Sea). In the Barents Sea population, timing of hatching was synchronized with the peak in food availability and there was strong stabilizing selection. Although birds in the Baltic and North Sea populations bred 6–7 weeks earlier than Arctic birds, timing of hatching was late in relation to the peak in food availability, and there was moderate to strong directional selection for early breeding. In the Baltic, absolute timing of egg laying advanced considerably over the 20‐year study period, but advanced little relative to spring phenology, and directional selection on lay date increased over time. Wing moult of adults started only 2–4 weeks earlier in the temperate populations than in the Arctic. Synchronization between fledging of young and end of wing moult decreased in the temperate populations. Arctic‐breeding geese may gradually accumulate body stores from the food they encounter during spring migration, which allows them to breed relatively early and their young to use the peak of the Arctic food resources. By contrast, temperate‐breeding birds are not able to acquire adequate body stores from local resources early enough, that is before the quality of food for their young starts to decrease. When global temperatures continue to rise, Arctic‐breeding barnacle geese might encounter similar problems.
Soil organic matter dynamics during 80 years of reforestation of tropical pastures
Authors: MARIN‐SPIOTTA ERIKA , SILVER WHENDEE L. , SWANSTON CHRISTOPHER W. , OSTERTAG REBECCA
Published: November 2008

Our research takes advantage of a historical trend in natural reforestation of abandoned tropical pastures to examine changes in soil carbon (C) during 80 years of secondary forest regrowth. We combined a chronosequence approach with differences in the natural abundance of 13C between C3 (forest) and C4 (pasture) plants to estimate turnover times of C in the bulk soil and in density fractions. Overall, gains in secondary forest C were compensated for by the loss of residual pasture‐derived soil C, resulting in no net change in bulk soil C stocks down to 1 m depth over the chronosequence. The free light fraction (LF), representing physically unprotected particulate organic matter, was most sensitive to land‐use change. Reforestation replenished C in the free LF that had been depleted during conversion to pastures. Turnover times varied with model choice, but in general, soil C cycling rates were rapid for the 0–10 cm depth, with even the heavy fraction (HF) containing C cycling in decadal time scales. Turnover times of C in the free LF from the 0–10 cm depth were shorter than for the occluded and HFs, highlighting the importance of physical location in the soil matrix for residence time in the soil. The majority of the soil C pool (82±21%) was recovered in the mineral‐associated density fraction. Carbon‐to‐nitrogen ratios and differences in natural abundance 15N of soil organic matter (SOM) showed an increasing degree of decomposition across density fractions with increasing mineral association. Our data show that the physical distribution of C in the soil has a large impact on soil C turnover and the ability of soils to maintain SOM stocks during land‐use and land‐cover change.
Copepod life cycle adaptations and success in response to phytoplankton spring bloom phenology
Authors: SEEBENS HANNO , EINSLE ULRICH , STRAILE DIETMAR
Published: November 2008

In a seasonal environment, the timing of reproduction is usually scheduled to maximize the survival of offspring. Within deep water bodies, the phytoplankton spring bloom provides a short time window of high food quantity and quality for herbivores. The onset of algal bloom development, however, varies strongly from year to year due to interannual variability in meteorological conditions. Furthermore, the onset is predicted to change with global warming. Here, we use a long‐term dataset to study (a) how a cyclopoid copepod, Cyclops vicinus, is dealing with the large variability in phytoplankton bloom phenology, and (b) if bloom phenology has an influence on offspring numbers. C. vicinus performed a two‐phase dormancy, that is, the actual diapause of fourth copepodid stages at the lake bottom is followed by a delay in maturation, that is, a quiescence, within the fifth copepodid stage until the start of the spring bloom. This strategy seems to guarantee a high temporal match of the food requirements for successful offspring development, especially through the highly vulnerable naupliar stages, with the phytoplankton spring bloom. However, despite this match with food availability in all study years, offspring numbers, that is, offspring survival rates were higher in years with an early start of the phytoplankton bloom. In addition, the phenology of copepod development suggested that also within study years, early offspring seems to have lower mortality rates than late produced offspring. We suggest that this is due to a longer predator‐free time period and/or reduced time stress for development. Hence, within the present climate variability, the copepod benefited from warmer spring temperatures resulting in an earlier phytoplankton spring bloom. Time will show if the copepod's strategy is flexible enough to cope with future warming.
Response of ecosystem carbon exchange to warming and nitrogen addition during two hydrologically contrasting growing seasons in a temperate steppe
Authors: XIA JIANYANG , NIU SHULI , WAN SHIQIANG
Published: November 2008

A large remaining source of uncertainty in global model predictions of future climate is how ecosystem carbon (C) cycle feedbacks to climate change. We conducted a field manipulative experiment of warming and nitrogen (N) addition in a temperate steppe in northern China during two contrasting hydrological growing seasons in 2006 [wet with total precipitation 11.2% above the long‐term mean (348 mm)] and 2007 (dry with total precipitation 46.7% below the long‐term mean). Irrespective of strong intra‐ and interannual variations in ecosystem C fluxes, responses of ecosystem C fluxes to warming and N addition did not change between the two growing seasons, suggesting independence of warming and N responses of net ecosystem C exchange (NEE) upon hydrological variations in the temperate steppe. Warming had no effect on NEE or its two components, gross ecosystem productivity (GEP) and ecosystem respiration (ER), whereas N addition stimulated GEP but did not affect ER, leading to positive responses of NEE. Similar responses of NEE between the two growing seasons were due to changes in both biotic and abiotic factors and their impacts on ER and GEP. In the wet growing season, NEE was positively correlated with soil moisture and forb biomass. Negative effects of warming‐induced water depletion could be ameliorated by higher forb biomass in the warmed plots. N addition increased forb biomass but did not affect soil moisture, leading to positive effect on NEE. In the dry growing season, NEE showed positive dependence on grass biomass but negative dependence on forb biomass. No changes in NEE in response to warming could result from water limitation on both GEP and ER as well as little responses of either grass or forb biomass. N addition stimulated grass biomass but reduced forb biomass, leading to the increase in NEE. Our findings highlight the importance of changes in abiotic (soil moisture, N availability) and biotic (growth of different plant functional types) in mediating the responses of NEE to climatic warming and N enrichment in the semiarid temperate steppe in northern China.
Long‐lasting effects on nitrogen cycling 12 years after treatments cease despite minimal long‐term nitrogen retention
Authors: CLARK CHRISTOPHER M. , HOBBIE SARAH E. , VENTEREA RODNEY , TILMAN DAVID
Published: November 2008

Atmospheric deposition of biologically active nitrogen (N) has increased dramatically over the past 60 years, with far‐reaching impacts on the structure and function of many ecosystems. Much research has examined the initial impacts of N enrichment; however, few studies have been multidecadal, and even fewer long‐term studies have examined the longevity of N‐induced impacts on N cycling after inputs cease. Here, we address this gap by reporting the state of key N pools and fluxes in a Minnesota grassland for plots that received N addition for 10 years and then none for 12 years, in comparison with plots that received annual N treatment for the entire 22 years. We found weak evidence for long‐term N retention in plots that ceased receiving treatment; and in plots that continued to receive N over the 22‐year period, retention that was high after 12 years (50–100% of inputs) was greatly reduced after 22 years (to 15%). In spite of this, net N mineralization rates remained elevated in plots that ceased receiving treatment 12 years prior, likely because N‐rich litter maintained higher N‐cycling rates. These results suggest (1) some systems do not retain much deposited N, with potentially large impacts on downstream habitats; (2) the previously reported high retention efficiencies for this and many other terrestrial ecosystems may be relatively short‐lived as N sinks become saturated over time; and (3) the effects of even small amounts of retained N in N‐limited environments may be particularly long‐lasting. In total, these findings highlight the importance of long‐term studies in evaluating the impacts of chronic N deposition to ecosystems, and urge additional research examining dynamics following N cessation to evaluate the reversibility of these impacts.
Comparison of the impacts of consumers, ambient UV, and future UVB irradiance on mid‐latitudinal macroepibenthic assemblages
Authors: MOLIS MARKUS , WAHL MARTIN
Published: November 2008

Future levels in ultraviolet‐B (UVB) radiation are expected to increase directly due to stratospheric ozone depletion and under water indirectly by, for example, global warming effects on DOC concentrations, altered trophic interactions in the plankton, or reduced eutrophication. While detrimental UV effects have been reported at the cellular level, little to nothing is known about community‐wide effects of ambient and future UVB radiation. In a 4‐month field experiment, the ambient UV regime was (i) reduced by cut‐off filters which removed either UVB or total UV from the solar spectrum or (ii) increased to predicted future levels by UVB lamps. To allow relating the effects of present and future UV regimes to another important ecological control of community structure and diversity in subtidal marine habitats, consumer effects were quantified by an exclusion treatment under ambient light regimes. Ambient UV regimes did not affect community structure, biomass accrual, and diversity. In contrast, under enhanced UVB levels, the dominance of the competitively superior blue mussels increased and species richness and biomass accrual decreased. Species composition of the assemblages differed between the two UV regimes. Effects of enhanced UVB radiation and of consumption on biomass accrual, diversity, and structure of the community were comparable in magnitude and timing, but of opposite direction. In contrast, the effects of enhanced UVB radiation on growth and abundance of mussels were in the same direction, but shorter and weaker than consumer effects. Most UV effects were transitory and vanished within the first 2 months of succession. Our results indicate that present and future UVB levels may be of limited importance and not stronger in effect size than other ecological controls in structuring the shallow‐water low‐diversity macrobenthic communities in temperate regions.
The land–atmosphere water flux in the tropics
Authors: FISHER JOSHUA B. , MALHI YADVINDER , BONAL DAMIEN , DA ROCHA HUMBERTO R. , DE ARAÚJO ALESSANDRO C. , GAMO MINORU , GOULDEN MICHAEL L. , HIRANO TAKASHI , HUETE ALFREDO R. , KONDO HIROAKI , KUMAGAI TOMO'OMI , LOESCHER HENRY W. , MILLER SCOTT , NOBRE ANTONIO D. , NOUVELLON YANN , OBERBAUER STEVEN F. , PANUTHAI SAMREONG , ROUPSARD OLIVIER , SALESKA SCOTT , TANAKA KATSUNORI , TANAKA NOBUAKI , TU KEVIN P. , VON RANDOW CELSO
Published: November 2008

Tropical vegetation is a major source of global land surface evapotranspiration, and can thus play a major role in global hydrological cycles and global atmospheric circulation. Accurate prediction of tropical evapotranspiration is critical to our understanding of these processes under changing climate. We examined the controls on evapotranspiration in tropical vegetation at 21 pan‐tropical eddy covariance sites, conducted a comprehensive and systematic evaluation of 13 evapotranspiration models at these sites, and assessed the ability to scale up model estimates of evapotranspiration for the test region of Amazonia. Net radiation was the strongest determinant of evapotranspiration (mean evaporative fraction was 0.72) and explained 87% of the variance in monthly evapotranspiration across the sites. Vapor pressure deficit was the strongest residual predictor (14%), followed by normalized difference vegetation index (9%), precipitation (6%) and wind speed (4%). The radiation‐based evapotranspiration models performed best overall for three reasons: (1) the vegetation was largely decoupled from atmospheric turbulent transfer (calculated from Ω decoupling factor), especially at the wetter sites; (2) the resistance‐based models were hindered by difficulty in consistently characterizing canopy (and stomatal) resistance in the highly diverse vegetation; (3) the temperature‐based models inadequately captured the variability in tropical evapotranspiration. We evaluated the potential to predict regional evapotranspiration for one test region: Amazonia. We estimated an Amazonia‐wide evapotranspiration of 1370 mm yr−1, but this value is dependent on assumptions about energy balance closure for the tropical eddy covariance sites; a lower value (1096 mm yr−1) is considered in discussion on the use of flux data to validate and interpolate models.
Long‐term prophylaxis in severe haemophilia seems to preserve bone mineral density
Authors: KHAWAJI M. , ÅKESSON K. , BERNTORP E.
Published: November 2008

Summary.  It has been previously shown that patients with severe haemophilia and not receiving any prophylactic treatment render a high risk of reduced bone mineral density. The purpose of this study was to evaluate bone mineral density (BMD) in patients with haemophilia of different severity types and treatment. The study group consisted of 26 patients with severe haemophilia (aged 33.6 ± 2.1) and 16 patients with mild haemophilia (aged 40.2 ± 3.3). The BMD (g cm−2) was measured by dual‐energy X‐ray absorptiometry (DXA). Physical activity was assessed by a self‐report questionnaire. Physical activity was scored as duration (h week−) and as metabolic physical activity score by weighing the intensity (MET‐h week−1). Joints were evaluated according to a physical examination score. There was no significant difference in BMD at lumbar spine L1–L4 (mild, 1.214 vs. severe, 1.175; P = 0.329), total hip (1.085 vs. 1.001, P = 0.114), femoral neck (1.036 vs. 0.977, P = 0.265), trochanter (0.896 vs. 0.820, P = 0.131) and whole body (1.215 vs. 1.183, P = 0.325) between those with mild and severe haemophilia. Based on Z‐score, both groups had normal BMD (Z score >−1). In patients with severe haemophilia, there was a significant correlation between joint evaluation score and BMD at total hip (P < 0.0001), femoral neck (P = 0.0003) and trochanter (P = 0.003). Physical activity did not correlate to disease severity. We did not observe a correlation between BMD and severity of haemophilia. The results indicate that the use of factor prophylaxis since early childhood may preserve normal BMD in severe haemophilia.
Relationship Between Social Rank and Cortisol and Testosterone Concentrations in Male Cynomolgus Monkeys (Macaca fascicularis)
Authors: Czoty P. W. , Gould R. W. , Nader M. A.
Published: November 2008

In nonhuman primate social groups, biological differences related to social status have proven useful for investigating the mechanisms of sensitivity to various disease states. Physiological and neurobiological differences between dominant and subordinate monkeys have been interpreted in the context of chronic social stress. The present experiments were designed to investigate the relationships between basal cortisol and testosterone concentrations and the establishment and maintenance of the social hierarchy in male cynomolgus monkeys. Cortisol concentrations were measured at baseline and following suppression with dexamethasone (DEX) and subsequent administration of adrenocorticotrophic hormone (ACTH) while monkeys were individually housed (n = 20) and after 3 months of social housing (n = 4/group), by which time dominance hierarchies had stabilised. Cortisol was also measured during the initial 3 days of social housing. Neither pre‐social housing hormone concentrations, nor hypothalamic‐pituitary‐adrenal (HPA) axis sensitivity predicted eventual social rank. During initial social housing, cortisol concentrations were significantly higher in monkeys that eventually became subordinate; this effect dissipated within 3 days. During the 12 weeks of social housing, aggressive and submissive behaviours were observed consistently, forming the basis for assignment of social ranks. At this time, basal testosterone and cortisol concentrations were significantly higher in dominant monkeys and, after DEX suppression, cortisol release in response to a challenge injection of ACTH was significantly greater in subordinates. These results indicate that basal cortisol and testosterone concentrations and HPA axis function are state variables that differentially reflect position in the dominance hierarchy, rather than trait variables that predict future social status.
Progesterone Attenuates Oestrogen Neuroprotection Via Downregulation of Oestrogen Receptor Expression in Cultured Neurones
Authors: Jayaraman A. , Pike C. J.
Published: November 2008

Recent findings indicate that progesterone can attenuate the beneficial neural effects of oestrogen. In the present study, we investigated the hypothesis that progesterone can modulate oestrogen actions by regulating the expression and activity of oestrogen receptors, ERα and ERβ. Our studies in cultured neurones demonstrate that progesterone decreases the expression of both ERα and ERβ and, as a consequence, also reduces both ER‐dependent transcriptional activity and neuroprotection. These results identify a potential mechanism by which progesterone antagonises neural oestrogen actions, a finding that may have important implications for hormone therapy in postmenopausal women.
Thyroid Hormone Receptor Alpha Plays an Essential Role in the Normalisation of Adult‐Onset Hypothyroidism‐Related Hypoexpression of Synaptic Plasticity Target Genes in Striatum
Authors: Vallortigara J. , Chassande O. , Higueret P. , Enderlin V.
Published: November 2008

Thyroid hormone (TH) deficiency leads to molecular changes resulting in behavioural deficits. TH action is mediated by two types of nuclear receptors (TRs), TRα and TRβ, which control target gene transcription. The relative contributions of the two TR products in mediating adult TH responses are poorly understood. As TRα1 transcripts are widely distributed in the brain, they presumably mediate most of the TH effects. This report examines the role and specific functions of T3 receptor isoforms on regulation of striatal synaptic plasticity indicators using adult hypothyroid mutant mice that fail to express single or multiple TR gene products. We then evaluated the effect of this hypothyroidism, with or without subsequent administration of T3, on T3 nuclear receptor (TRα1, TRβ) and synaptic plasticity gene expression in TRα0/0, TRβ−/− and wild‐type 129/SV mice. Hypothyroid wild‐type mice exhibited reduced TRβ, RC3, CaMKII and Rhes expression. The mRNA levels of Rhes and CaMKII were the same in all three hypothyroid substrains. By contrast, hypothyroid TRβ−/− mice had higher RC3 mRNA levels than wild‐type. T3 administration restored TRβ, RC3 and CaMKII levels in hypothyroid wild‐type mice, without significant Rhes upregulation. T3 administration normalised expression of all genes studied in hypothyroid TRβ−/− but not TRα0/0 mice. Thus, TRα apparently plays an essential role in restoring the expression of the TH‐regulated genes potentially involved in striatal synaptic plasticity.
Mating‐Induced Neuroendocrine Responses During Pseudopregnancy in the Female Mouse
Authors: Yang J. J. , Larsen C. M. , Grattan D. R. , Erskine M. S.
Published: November 2008

Pseudopregnancy (PSP) is a neuroendocrine reflex triggered by vaginocervical stimulation similar to the neuroendocrine response of early pregnancy and is characterised by short‐term neural activity, resulting in long‐term neuroendocrine responses that cause repeated release of pituitary prolactin (PRL) over many days. PSP is a useful model to study how somatosensory input is transduced in the brain into neuroendocrine responses, and has been extensively characterised in rats. With increasing use of mice as an experimental model, however, and to allow use of transgenic mice to investigate mechanisms of this sensory response, it is important to characterise the principal neuroendocrine response of pseudopregnancy in this species. The present study aimed to examine the induction and neuroendocrine responses of PSP in mice using vasectomised stud males, to investigate mating‐induced changes in vaginal cytology, uterine growth, and PRL secretion, and to map certain aspects of somatosensory transduction by assessing the neural activity marker FOS. Unlike the induction of pseudopregnancy in rats, which can be induced simply by multiple intromissions from a male or artificial mechanical stimulation of the cervix, PSP induction in mice required the receipt of an ejaculation from a male. In mice that received PSP‐inducible mating stimuli, FOS expression was observed in a slightly different range of brain regions than has been observed in rats, with increases in the bed nucleus of the stria terminalis, medial preoptic area, and ventromedial hypothalamus, but not in limbic areas examined. Moreover, PSP mice expressed a single diurnal PRL surge on day 6 of PSP. Thus, the data demonstrate important species differences in the neuroendocrine mechanisms activated in response to a mating stimulus in mice compared with rats. A clear understanding of the species‐specific response will be required in interpreting research into the reproductive biology of this species.
Serotonergic and Catecholaminergic Interactions with Co‐Localised Dopamine‐Melatonin Neurones in the Hypothalamus of the Female Turkey
Authors: Kang S. W. , Leclerc B. , Mauro L. J. , El Halawani M. E.
Published: November 2008

Serotonin and catecholamines (dopamine, norepinephrine, epinephrine) have important roles as neurotransmitters in avian reproduction, but their anatomical relationship to the neuroendocrine circuitry that regulates reproduction is poorly understood. Our previous studies have shown that co‐localised dopamine‐melatonin (DA‐MEL) neurones in the avian premammillary nucleus (PMM) are active during periods of photoresponsiveness and, therefore, are potentially photosensitive neurones. Because serotonergic and catecholaminergic neurotransmitters are important regulators of reproductive function in the female turkey, we hypothesised that the serotonergic/catecholaminergic neurones within the brainstem might interact with PMM DA‐MEL neurones and constitute an important circuit for reproductive function. To examine this possible interaction, the retrograde fluorescent tract tracer, 1,1′dioctadecyl‐3,3,3′3′‐tetramethyleindocarbocyanine perchlorate (DiI) was injected into the PMM, and combined with serotonin, tyrosine hydroxylase (TH), dopamine β‐hydroxylase (DBH) and phenylN‐methyltransferse (PNMT) immunocytochemistry to reveal neuroanatomical connections. Changes in the activities of serotonergic, dopaminergic, adrenergic and noradrenergic neuronal systems projecting to the PMM were measured at different reproductive states within situhybridisation (ISH) techniques, using tryptophan hydroxylase 2 (TPH2) and TH mRNA expression, respectively. Cells labelled with DiI were found in anatomically discrete areas in or near the hypothalamus and the brainstem. Double immunocytochemistry confirmed that there were serotonin, DBH and PNMT fibres in close apposition to DA‐MEL neurones. TPH2 mRNA expression in serotonin neurones was found in several nuclei, and its most abundant mRNA expression was seen in the nucleus Locus ceruleus of laying and incubating hens. TH mRNA expression levels in the six catecholaminegic areas labelled with DiI was measured across the different reproductive states. In the nucleus tractus solitarius (adrenergic), the highest level of TH mRNA expression was found in photorefractory hens and the lowest level in incubating hens. These observed patterns of serotonin/catecholamine neuronal distribution and their variable interactions with PMM DA‐MEL neurones during different reproductive states may offer a significant neuroanatomical basis for understanding the control of avian reproductive seasonality.
Perinatal Undernutrition Modifies Cell Proliferation and Brain‐Derived Neurotrophic Factor Levels During Critical Time‐Windows for Hypothalamic and Hippocampal Development in the Male Rat
Authors: Coupé B. , Dutriez‐Casteloot I. , Breton C. , Lefèvre F. , Mairesse J. , Dickes‐Coopman A. , Silhol M. , Tapia‐Arancibia L. , Lesage J. , Vieau D.
Published: November 2008

Maternal perinatal undernutrition (MPU) modifies the activity of the hypothalamic‐pituitary‐adrenal axis and sensitises to the development of metabolic and cognitive adult diseases. Because the hypothalamus and hippocampus are involved in the regulation of neuroendocrine activity, energy metabolism and cognition, we hypothesised that a maternal 50% food restriction (FR50) from day 14 of pregnancy (E14) until postnatal day 21 (P21) would affect the development of these structures in male rat offspring. Protein and mRNA levels of brain‐derived neurotrophic factor (BDNF) and cell proliferation [analysed by 5‐bromodeoxyuridine (BrdU) incorporation] were compared in both control and FR50 rats from E21 to P22. Although the pattern of the evolution of BDNF concentration and cell proliferation throughout development was not strikingly different between groups, several disturbances at specific developmental stages were observed. FR50 rats exhibited a delayed increase of hippocampal BDNF content whereas, in the hypothalamus, BDNF level was augmented from E21 to P14 and associated, at this latter stage, with an increased mRNA expression of TRkB‐T2. In both groups, a correlation between BDNF content and the number of BrdU positive cells was noted in the dentate gyrus, whereas opposite variations were observed in CA1, CA2 and CA3 layers, and in the arcuate and ventromedial nuclei. In the hippocampus, P15‐FR50 rats showed an increased number of BrdU positive cells in all regions, whereas, at P22, a decrease was observed in the CA2. In the hypothalamus, between E21 and P8, MPU increases the number of BrdU positive cells in all regions analysed and, until P15, marked differences were noticed in the median eminence, the paraventricular nucleus and the arcuate nucleus. Taken together, the results obtained in the present study show that MPU changes the time course of production of BDNF and cell proliferation in specific hippocampal and hypothalamic areas during sensitive developmental windows, suggesting that these early perinatal modifications may have long‐lasting consequences.
Down‐Regulation of Hypothalamic Kisspeptin and its Receptor, Kiss1r, mRNA Expression is Associated with Stress‐Induced Suppression of Luteinising Hormone Secretion in the Female Rat
Authors: Kinsey‐Jones J. S. , Li X. F. , Knox A. M. I. , Wilkinson E. S. , Zhu X. L. , Chaudhary A. A. , Milligan S. R. , Lightman S. L. , O’Byrne K. T.
Published: November 2008

Identification of kisspeptin (Kiss1) and its G protein‐coupled receptor 54 (Kiss1r) as an essential component of the hypothalamic‐pituitary‐gonadal (HPG) axis controlling gonadotrophin secretion raises the possibility that kisspeptin‐Kiss1r signalling may play a critical role in the transduction of stress‐induced suppression of reproduction. We examined the effects of: (i) three different stressors, known to suppress pulsatile luteinising hormone (LH) secretion; (ii) corticotrophin‐releasing factor (CRF); and (iii) corticosterone on Kiss1 and Kiss1r expression in key hypothalamic sites regulating gonadotrophin secretion: the medial preoptic area (mPOA) and arcuate nucleus (ARC). Ovariectomised oestrogen‐replaced rats were implanted with i.v., subcutaneous or i.c.v. cannulae. Blood samples were collected at 5‐min intervals for 5–6 h for detection of LH. Quantitative reverse transcriptase‐polymerase chain reaction was used to determine Kiss1 and Kiss1r mRNA levels in brain punches of the mPOA and ARC collected 6 h after restraint, insulin‐induced hypoglycaemia or lipopolysaccharide stress, or after i.c.v. administration of CRF, or acute or chronic subcutaneous administration of corticosterone. We observed down‐regulation of at least one component of the kisspeptin‐Kiss1r signalling system by each of the stress paradigms within the mPOA and ARC. CRF decreased Kiss1 and Kiss1r expression in both the mPOA and ARC. Both acute and chronic stress levels of corticosterone resulted in a concomitant decrease in Kiss1 and an increase in kiss1r mRNA expression in the mPOA and ARC. This differential regulation of Kiss1 and Kiss1r might account for the lack of effect corticosterone has on pulsatile LH secretion. Considering the pivotal role for kisspeptin‐Kiss1r signalling in the control of the HPG axis, these results suggest that the reduced Kiss1‐Kiss1r expression may be a contributing factor in stress‐related suppression of LH secretion.
What are the nursing implications when using paliperidone prolonged release for people with schizophrenia
Authors: JONES A.
Published: November 2008

Paliperidone prolonged release (PR) is a new product licensed for the treatment of schizophrenia. It is the active metabolite of risperidone, a drug that has been successfully used in the treatment of schizophrenia and mood disorder. Paliperidone PR has a unique pharmacological delivery mechanism that may incur benefits for particular patients diagnosed with schizophrenia. Studies investigating paliperidone PR are reviewed along with implications for its use by nurse prescribers and those nurses who monitor the use of medication for people with psychosis.
Clinical formulation for mental health nursing practice
Authors: Crowe M. , Carlyle D. , Farmar R.
Published: November 2008

There are problems for mental health nurses in using psychiatric diagnoses as outcomes of their nursing assessments and nursing diagnoses present similar issues. However, there is a need in practice to link the assessment to nursing interventions in a meaningful way. This paper proposes that the clinical formulation can be regarded as central to providing this cohesion. The formulation does not merely organize the assessment findings but is also an interpretation or explanation, made in consultation with the client, of what meaning can be attributed to the issues explored in the assessment process. Because this interpretation is dependent on both the client's and the nurse's explanatory frameworks, there are multiple ways of developing the formulation. It is also an evolving and dynamic statement of understanding. A case example is provided in the paper to illustrate how the same case can be interpreted in different ways and the implications this has for the nursing interventions provided.
The effects of physical exercises to mental state and quality of life in patients with schizophrenia
Authors: ACIL A. A. , DOGAN S. , DOGAN O.
Published: November 2008

The purpose of this study was to examine the effects of 10 weeks of physical exercises programme on mental states and quality of life (QOL) of individuals with schizophrenia. The study involved 30 inpatients or outpatients with schizophrenia who were assigned randomly into aerobic exercise (n = 15) group and control (n = 15) group, participated to the study voluntarily. There were no personal differences such as age, gender, disorder duration, medication use between the both groups. An aerobic exercise programme was applied to the subject group, the periods of 10 weeks as 3 days in a week. Data were collected by using the Brief Symptom Inventory, the Scale for the Assessment of Positive Symptoms, the Scale for the Assessment of Negative Symptoms and to the both group before and after the exercise programme. After the 10‐week aerobic exercise programmes the subjects in the exercise programme showed significantly decreases in the Scale for the Assessment of Positive Symptoms, the Scale for the Assessment of Negative Symptoms and the Brief Symptom Inventory points and their World Health Organization Quality of Life Scale‐Turkish Version points were increased than controls. These results suggest that mild to moderate aerobic exercise is an effective programme for decreasing psychiatric symptoms and for increasing QOL in patients with schizophrenia.
New ways of working: how mental health practitioners perceive their training and role
Authors: BROWN J. , SIMONS L. , ZEEMAN L.
Published: November 2008

This paper outlines advances in the mental health workforce by detailing the development, education and training of graduates from the social sciences in mental health practice. The mental health practitioner (MHP) programme is a partnership between higher education and the National Health Service to provide graduates with a new point of entry into the mental health workforce. The MHP is a new role in mental health i.e. in principle, trans‐disciplinary, traversing psychology, nursing and occupational therapy. The role is informed by a bio‐psychosocial philosophy of collaborative mental health care and therefore acts as a bridge between the different professions that constitute a multidisciplinary team on acute inpatient units and in the community. However, MHPs form part of the nursing team and work most closely with mental health nurses. They see their role as linked to, but other than, nursing. This paper will discuss the development of this programme and its philosophy of care, and will present outcome research on trainee perceptions and experiences of occupying the MHP role in mental health. It will present findings from the first stage of a longitudinal study (employing interviews and survey data) about trainee perceptions of their role and training before the programme commenced, 6 months into their training and at graduation.
The relationship between community violence exposure and mental health symptoms in urban adolescents
Authors: McDONALD C. C. , RICHMOND T. R.
Published: November 2008

Urban adolescents are exposed to a substantial amount of community violence which has the potential to influence psychological functioning. To examine the relationship between community violence exposure and mental health symptoms in urban adolescents, a literature review using MEDLINE, CINAHL, PubMed, PsycINFO, CSA Social Services and CSA Sociological Abstracts was conducted. Search terms included adolescent/adolescence, violence, urban, mental health, well‐being, emotional distress, depression, anxiety, posttraumatic stress disorder and aggression. Twenty‐six empirical research articles from 1997 to 2007 met inclusion criteria for review. Findings indicate an influence of community violence exposure on mental health symptoms, particularly posttraumatic stress and aggression. Mediators and moderators for community violence exposure and mental health symptoms help explain relationships. Limitations in the literature are the lack of consistency in measurement and analysis of community violence exposure, including assessment of proximity and time frame of exposure, and in analysis of victimization and witnessing of community violence. Knowledge about identification of urban adolescents exposed to chronic community violence and who experience mental health symptoms is critical to mental health nursing practice and research.
Cognitive behaviour therapy within assertive outreach teams: barriers to implementation: a qualitative peer audit
Authors: WILLIAMS C. H. J.
Published: November 2008

Assertive outreach is an evidence‐based intervention, with over 30 well‐designed randomized studies demonstrating its effectiveness, predominately in the USA. Assertive outreach teams have recently been implemented in the UK, and it has been recommended that teams should offer cognitive behaviour therapy (CBT) to service users; however, it has been reported that barriers exist in the routine delivery of CBT for psychosis (CBTp). The aim of the peer audit was to gauge current opinion from clinicians whether their experiences of barriers to implementation of CBTp reflected that outlined in the literature. A qualitative peer audit was undertaken at the National Forum for Assertive Outreach Annual Conference in 2006. The team representatives were invited to outline the barriers to the implementation of psychosocial interventions within their local areas. Teams identified organizational, managerial, supervision and local specific barriers to implementation. Specific comments included a lack of organizational investment, the structured nature of CBT, caseload issues, medication issues, application to people with sensory impairments, staff apathy and staff burnout. The analysis was limited by the metholodology employed; however, further recommendations are explored. It was evident from this peer audit that teams are experiencing barriers relating to the implementation of evidence‐based therapy interventions and further research is required on the outreach model and the use of CBTp.
Bioavailability of veterinary drugsin vivoandin silico
Authors: GRABOWSKI T. , JAROSZEWSKI J. J.
Published: November 2008

The physical and chemical properties of a drug determine the behaviour of its molecule in a living organism. In this paper, the relationship between selected physical and chemical parameters and drug bioavailabilityin vivowas investigated. Data sets from 75 compounds, which can be administeredper osto 11 various animal species were analyzed. The selected parameters for the prediction of thein vivobioavailability were the lipophilicity (LogP) and the polar surface area (PSA) or apolar surface area (aPSA) of a molecule. It was shown that the calculation of the hybrid parameters aPSA/PSA and LogP + (aPSA/PSA) allows to estimate the oral bioavailability of a drug and its allocation to clusters with either an oral bioavailability of <70% or >70%. The performed analysis also showed that an extreme low value of the PSA of a molecule (<40 square ångströms) combined with the extreme high value of LogP (>4) is associated with a lower oral bioavailability (<50%). The results obtained indicate the existence of a relationship between the mean LogP value and aPSA/PSAin silico, and the bioavailability of veterinary drugs as determinedin vivo.
Geostatistical genetic analysis for inferring the dispersal pattern of a partially clonal species: example of the chestnut blight fungus
Authors: DUTECH C. , ROSSI J.‐P. , FABREGUETTES O. , ROBIN C.
Published: November 2008

Spatial genetic analyses can be used to infer dispersal processes in natural populations. For partially clonal species with alternating sexual and asexual reproduction, the repetition of genotypes must be taken into account in analyses. The methods currently employed to evaluate the relevance of the spatial scale used for the estimation of gene flow are not suitable for these species. We investigated recently developed methods for taking into account repeated genotypes and for determining whether the sampling scale is large enough to capture all the spatial genetic structure existing within a population. We applied these methods to a fungal plant pathogen species,Cryphonectria parasitica,which has caused the death of many American and European chestnut trees since its introduction from Asia at the beginning of the 20th century. These methods were found to be useful for unravelling the effects of clonality and historical gene flow on the spatial genetic structure, and indicated that dispersal processes have probably occurred over a larger spatial scale than previously assumed.