Soil legacies of tree species richness in a young plantation do not modulate tree seedling response to watering regime

Trees have a strong and species-specific influence on biotic and abiotic properties of the soil. Even after the vegetation is removed, the effect can persist to form so-called soil legacies. We investigated the effects of soil legacies of tree species richness on the emergence and growth of tree seedlings, and how these legacy effects modulate the seedling responses to irrigation frequency. We used a 9-year-old tree plantation on former agricultural land in Belgium, which is part of a biodiversity-ecosystem functioning experiment (FORBIO). Soil originating from monocultures and four-species plots, with different species combinations, was translocated to a greenhouse. Five tree species (Betula pendula, Fagus sylvatica, Pinus sylvestris, Quercus robur, and Tilia cordata) were sown and grown for one growing season in these soils. We performed a watering treatment (low and high irrigation frequency) to measure any potential interaction effects between the soil legacies and irrigation frequency. There was no evidence for soil legacy effects of species richness on plant performance or their response to the irrigation frequency. However, the effect of irrigation frequency was dependent on species identity of the tree seedlings. Despite the lack of clear legacy effects, performance measures did show correlated responses that are likely due to species composition effects. We ascribe these patterns to the young age of the forest and the agricultural past land use. At this early stage in forest development, the land-use history likely has a more important role in shaping soil characteristics that affect plant growth and their response to drought, than species diversity.

Learning objectives of Belgian general practitioner trainees regarding their hospital training: A qualitative study

Background

In Europe, hospital training is integrated in the postgraduate curriculum of General Practitioners (GPs) according to the European Directives. However, little is known about the specific learning objectives of GP trainees during this training.

Objectives

This exploratory study investigated GP trainees’ expected learning objectives for their hospital training and the factors influencing the learning process.

Methods

Semi-structured interviews were conducted in three focus groups consisting of first-year GP trainees before their hospital training. Data were coded thematically and analysed in NVivo.

Results

A total of 22 Belgian GP trainees (55% females, average age of 26.2 years) were interviewed. Three major themes emerged: learning objectives, factors influencing learning and organisational aspects. GP trainees mainly wanted to improve their knowledge of common conditions by conducting consultations and follow certain patients’ hospitalisation trajectory. Emergency medicine or internal medicine was the preferred specialty. Other GP trainees wanted to learn more about some specific conditions. Conversely, an overloaded work schedule was dreaded to hinder effective learning. Regular meetings and supervision from their hospital trainer were deemed crucial to strengthen GP trainees’ learning trajectory.

Conclusion

GP trainees wanted to learn more about both common conditions and some specific conditions. Their previous year in a GP setting strengthened their confidence and facilitated purposeful learning. Relieving GP trainees from administrative tasks when working as supplementary doctors could strike a better balance between the continuity of the clinical department and their personal learning objectives.

Initial oak regeneration responses to experimental warming along microclimatic and macroclimatic gradients

Quercus spp. are one of the most important tree genera in temperate deciduous forests in terms of biodiversity, economic and cultural perspectives. However, natural regeneration of oaks, depending on specific environmental conditions, is still not sufficiently understood. Oak regeneration dynamics are impacted by climate change, but these climate impacts will depend on local forest management and light and temperature conditions. Here, we studied germination, survival and seedling performance (i.e. aboveground biomass, height, root collar diameter and specific leaf area) of four oak species (Q. cerris, Q. ilex, Q. robur and Q. petraea). Acorns were sown across a wide latitudinal gradient, from Italy to Sweden, and across several microclimatic gradients located within and beyond the species' natural ranges. Microclimatic gradients were applied in terms of forest structure, distance to the forest edge and experimental warming. We found strong interactions between species and latitude, as well as between microclimate and latitude or species. The species thus reacted differently to local and regional changes in light and temperature ; in southern regions the temperate Q. robur and Q. petraea performed best in plots with a complex structure, whereas the Mediterranean Q. ilex and Q. cerris performed better in simply structured forests with a reduced microclimatic buffering capacity. The experimental warming treatment only enhanced height and aboveground biomass of Mediterranean species. Our results show that local microclimatic gradients play a key role in the initial stages of oak regeneration; however, one needs to consider the species-specific responses to forest structure and the macroclimatic context.

Different effects of warming treatments in forests versus hedgerows on the understorey plant Geum urbanum

The effectiveness of hedgerows as functional corridors in the face of climate warming has been little researched. Here we investigated the effects of warming temperatures on plant performance and population growth of Geum urbanum in forests versus hedgerows in two European temperate regions. Adult individuals were transplanted in three forest-hedgerow pairs in each of two different latitudes, and an experimental warming treatment using open-top chambers was used in a full factorial design. Plant performance was analysed using mixed models and population performance was analysed using Integral Projection Models and elasticity analyses. Temperature increases due to open-top chamber installation were higher in forests than in hedgerows. In forests, the warming treatment had a significant negative effect on the population growth rate of G. urbanum. In contrast, no significant effect of the warming treatment on population dynamics was detected in hedgerows. Overall, the highest population growth rates were found in the forest control sites, which was driven by a higher fecundity rather than a higher survival probability. Effects of warming treatments on G. urbanum population growth rates differed between forests and hedgerows. In forests, warming treatments negatively affected population growth, but not in hedgerows. This could be a consequence of the overall lower warming achieved in hedgerows. We conclude that maintenance of cooler forest microclimates coul, at least temporarily, moderate the species response to climate warming.

Forest understorey plant responses to long-term experimental warming, light and nitrogen addition

Climate change, eutrophication and intensified forest management are affecting forest understorey plants, a major component of forest biodiversity. The main impacts of these drivers have often been studied, but we lack a good understanding of how key understorey species are affected by potential interactive effects of these drivers and which species drive community changes. Here we assessed the responses of 15 species occurring in the understorey of a deciduous temperate forest to experimental warming, light addition and enhanced nitrogen inputs in permanent plots surveyed for 9 years. We analysed vegetation cover and key functional traits (plant height, specific leaf area and reproductive traits) at the species level and identified the species driving community change with principal response curves (PRC). Light addition and warming, and to a lesser extent also nitrogen addition, had profound effects on cover and functional traits. Many species showed directional change over time, and this change can either be strengthened or weakened by treatments, indicating the importance of long-term monitoring. Against expectations, we observed few interactions between treatments. Species responses to treatments were related to ecological strategies (generalists versus forest specialist). Generalists, such as Rubus fruticosus, benefitted from the warming and light treatments and outcompeted forest specialists. This might ultimately lead to biotic homogenization. Since the treatment effects of light and warming were additive, keeping the canopy closed will only mitigate, but not stop, the effects of global warming on the forest understorey plants.

Identifying key elements to inform HIV-testing interventions for primary care in Belgium

General practitioners (GPs) play a key role in reducing the hidden HIV-epidemic, but many diagnostic opportunities are missed in primary care. This study aimed at informing the development of an HIV-testing intervention for GPs in Flanders (Belgium) using formative research with a participatory approach. Through the active involvement of an advisory board and 16 group discussions with 122 Flemish GPs, GPs’ current HIV-testing practices and perceived practical relevance of 2 distinct HIV-testing strategies (i.e. provider-initiated testing of key populations and indicator condition-based testing) were explored in terms of their relevance and feasibility in routine primary care. Self-reported HIV-testing practices revealed that most tests performed were patient-initiated, pretest counseling was rarely done, and post-test counseling was offered mainly for patients with an HIV-diagnosis. GPs reported multiple barriers to provider-initiated HIV-testing, i.e. personal discomfort, fear of offending their patient, limited knowledge of benefits of early HIV-diagnosis, misconceptions about HIV-risks, lack of guidelines and time. Difficulties to identify patient’s sexual orientation or ethical concerns were mentioned as barriers for target group-based HIV testing. GPs assessed the current list of 64 indicator conditions as too difficult to integrate in routine care, deeming a reduced list of GP-relevant conditions as more feasible. Combined strategies (i.e. target group- and indicator-based testing) supported by official screening recommendations were perceived as successful strategies for provider-initiated HIV-testing in primary care. This formative research delivered qualitative evidence for the development of an HIV-testing intervention for primary care settings.

Individualistic responses of forest herb traits to environmental change

Intraspecific trait variation (ITV; i.e. variability in mean and/or distribution of plant attribute values within species) can occur in response to multiple drivers. Environmental change and land-use legacies could directly alter trait values within species but could also affect them indirectly through changes in vegetation cover. Increasing variability in environmental conditions could lead to more ITV, but responses might differ among species. Disentangling these drivers on ITV is necessary to accurately predict plant community responses to global change. We planted herb communities into forest soils with and without a recent history of agriculture. Soils were collected across temperate European regions, while the 15 selected herb species had different colonizing abilities and affinities to forest habitat. These mesocosms (384) were exposed to two-level full-factorial treatments of warming, nitrogen addition and illumination. We measured plant height and specific leaf area (SLA). For the majority of species, mean plant height increased as vegetation cover increased in response to light addition, warming and agricultural legacy. The coefficient of variation (CV) for height was larger in fast-colonizing species. Mean SLA for vernal species increased with warming, while light addition generally decreased mean SLA for shade-tolerant species. Interactions between treatments were not important predictors. Environmental change treatments influenced ITV, either via increasing vegetation cover or by affecting trait values directly. Species' ITV was individualistic, i.e. species responded to different single resource and condition manipulations that benefited their growth in the short term. These individual responses could be important for altered community organization after a prolonged period.

Plant functional trait response to environmental drivers across European temperate forest understorey communities

Functional traits respond to environmental drivers, hence evaluating trait-environment relationships across spatial environmental gradients can help to understand how multiple drivers influence plant communities. Global-change drivers such as changes in atmospheric nitrogen deposition occur worldwide, but affect community trait distributions at the local scale, where resources (e.g. light availability) and conditions (e.g. soil pH) also influence plant communities. We investigate how multiple environmental drivers affect community trait responses related to resource acquisition (plant height, specific leaf area (SLA), woodiness, and mycorrhizal status) and regeneration (seed mass, lateral spread) of European temperate deciduous forest understoreys. We sampled understorey communities and derived trait responses across spatial gradients of global-change drivers (temperature, precipitation, nitrogen deposition, and past land use), while integrating in-situ plot measurements on resources and conditions (soil type, Olsen phosphorus (P), Ellenberg soil moisture, light, litter mass, and litter quality). Among the global-change drivers, mean annual temperature strongly influenced traits related to resource acquisition. Higher temperatures were associated with taller understoreys producing leaves with lower SLA, and a higher proportional cover of woody and obligate mycorrhizal (OM) species. Communities in plots with higher Ellenberg soil moisture content had smaller seeds and lower proportional cover of woody and OM species. Finally, plots with thicker litter layers hosted taller understoreys with larger seeds and a higher proportional cover of OM species. Our findings suggest potential community shifts in temperate forest understoreys with global warming, and highlight the importance of local resources and conditions as well as global-change drivers for community trait variation.

Phenology and growth of Fagus sylvatica and Quercus robur seedlings in response to temperature variation in the parental versus offspring generation

Plants are known to respond to warming temperatures. Few studies, however, have included the temperature experienced by the parent plant in the experimental design, in spite of the importance of this factor for population dynamics. We investigated the phenological and growth responses of seedlings of two key temperate tree species (Fagus sylvatica and Quercus robur) to spatiotemporal temperature variation during the reproductive period (parental generation) and experimental warming of the offspring. To this end, we sampled oak and beech seedlings of different ages (1-5 years) from isolated mother trees and planted the seedlings in a common garden. Warming of the seedlings advanced bud burst in both species. In oak seedlings, higher temperatures experienced by mother trees during the reproductive period delayed bud burst in control conditions, but advanced bud burst in heated seedlings. In beech seedlings, bud burst timing advanced both with increasing temperatures during the reproductive period of the parents and with experimental warming of the seedlings. Relative diameter growth was enhanced in control oak seedlings but decreased with warming when the mother plant experienced higher temperatures during the reproductive period. Overall, oak displayed more plastic responses to temperatures than beech. Our results emphasise that temperature during the reproductive period can be a potential determinant of tree responses to climate change.

Plant-soil feedbacks of forest understorey plants transplanted in nonlocal soils along a latitudinal gradient

Climate change is driving movements of many plants beyond, as well as within, their current distributional ranges. Even migrant plants moving within their current range may experience different plant-soil feedbacks (PSF) because of divergent nonlocal biotic soil conditions. Yet, our understanding to what extent soil biotic conditions can affect the performance of within-range migrant plants is still very limited. We assessed the emergence and growth of migrant forest herbs (Milium effusum and Stachys sylvatica) using soils and seeds collected along a 1,700 km latitudinal gradient across Europe. Soil biota were manipulated through four soil treatments, i.e. unsterilized control soil (PSF_US ), sterilized soil (PSF_S ), sterilized soil inoculated with unsterilized home soil (PSF_S+HI ) and sterilized soil inoculated with unsterilized foreign soil (PSF_S+FI , expected to occur when both plants and soil biota track climate change). Compared to PSF_S , PSF_US had negative effects on the growth but not emergence of both species, while PSF_S+FI only affected S. sylvatica across all seed provenances. When considering seed origin, seedling emergence and growth responses to nonlocal soils depended on soil biotic conditions. Specifically, the home-away distance effect on seedling emergence differed between the four treatments, and significant responses to chemistry either disappeared (M. effusum) or changed (S. sylvatica) from PSF_US to PSF_S . Soil biota emerge as an important driver of the estimated plant migration success. Our results of the effects of soil microorganisms on plant establishment provide relevant information for predictions of the distribution and dynamics of plant species in a changing climate.

Clinical usefulness and challenges of instrumented motion analysis in patients with intellectual disabilities

BACKGROUND

Clinical laboratory testing of locomotor disorders is challenging in patients with intellectual disability (ID). Nevertheless, also in this population gait analysis has substantial value as motor problems are common. To promote its use, adequate protocols need to be developed and the impact on clinical decision making needs to be documented.

RESEARCH QUESTION

What is the clinical usefulness of instrumented motion analysis in patients with ID?

METHOD

This narrative review consists of three parts. A literature review was performed to describe the gait pattern of patients with ID. Next, benefits and challenges of standard gait analysis protocols are described. Finally, a case of a girl with ID due to genetic cause showing gait abnormalities is discussed.

RESULTS

The literature review resulted in 20 studies on "gait" in patients with an "ID", published since August, 1^st 2013. Gait deviations were observed in all studies investigating the ID population with an underlying genetic syndrome. Observed gait deviations in the ID population might be attributed to physical characteristics, cognitive components or both. The main goal of clinical gait assessment is the identification of gait deviations and the evaluation of their progress over time, in order to optimize the treatment plan. The choice of adequate method and measurement modalities depends on the clinical goal, the available resources and the abilities of the patient. In the case report we presented, we succeeded in performing an instrumented 3D gait analysis in a girl with severe ID at the ages of 4y4m, 6y0m, 7y2m and 8y2m. Progressive gait deviations were found suggesting a crouch gait pattern was developing. Results of the gait analysis led to the prescription of rigid ankle-foot orthoses.

SIGNIFICANCE

Gait analysis has substantial value for patients with ID. Gait analysis allows clinicians to objectify the relationship between physical characteristics and gait features.

Atmospheric nitrogen deposition on petals enhances seed quality of the forest herb Anemone nemorosa

Elevated atmospheric input of nitrogen (N) is currently affecting plant biodiversity and ecosystem functioning. The growth and survival of numerous plant species is known to respond strongly to N fertilisation. Yet, few studies have assessed the effects of N deposition on seed quality and reproductive performance, which is an important life-history stage of plants. Here we address this knowledge gap by assessing the effects of atmospheric N deposition on seed quality of the ancient forest herb Anemone nemorosa using two complementary approaches. By taking advantage of the wide spatiotemporal variation in N deposition rates in pan-European temperate and boreal forests over 2 years, we detected positive effects of N deposition on the N concentration (percentage N per unit seed mass, increased from 2.8% to 4.1%) and N content (total N mass per seed more than doubled) of A. nemorosa seeds. In a complementary experiment, we applied ammonium nitrate to aboveground plant tissues and the soil surface to determine whether dissolved N sources in precipitation could be incorporated into seeds. Although the addition of N to leaves and the soil surface had no effect, a concentrated N solution applied to petals during anthesis resulted in increased seed mass, seed N concentration and N content. Our results demonstrate that N deposition on the petals enhances bioaccumulation of N in the seeds of A. nemorosa. Enhanced atmospheric inputs of N can thus not only affect growth and population dynamics via root or canopy uptake, but can also influence seed quality and reproduction via intake through the inflorescences.

Modelling understorey dynamics in temperate forests under global change-Challenges and perspectives

The understorey harbours a substantial part of vascular plant diversity in temperate forests and plays an important functional role, affecting ecosystem processes such as nutrient cycling and overstorey regeneration. Global change, however, is putting these understorey communities on trajectories of change, potentially altering and reducing their functioning in the future. Developing mitigation strategies to safeguard the diversity and functioning of temperate forests in the future is challenging and requires improved predictive capacity. Process-based models that predict understorey community composition over time, based on first principles of ecology, have the potential to guide mitigation endeavours but such approaches are rare. Here, we review fourteen understorey modelling approaches that have been proposed during the last three decades. We evaluate their inclusion of mechanisms that are required to predict the impact of global change on understorey communities. We conclude that none of the currently existing models fully accounts for all processes that we deem important based on empirical and experimental evidence. Based on this review, we contend new models are needed to project the complex impacts of global change on forest understoreys. Plant functional traits should be central to such future model developments, as they drive community assembly processes and provide valuable information on the functioning of the understorey. Given the important role of the overstorey, a coupling of understorey models to overstorey models will be essential to predict the impact of global change on understorey composition and structure, and how it will affect the functioning of temperate forests in the future.

Salmonella Typhimurium DT193 and DT99 are present in great and blue tits in Flanders, Belgium

Endemic infections with the common avian pathogen Salmonella enterica subspecies enterica serovar Typhimurium (Salmonella Typhimurium) may incur a significant cost on the host population. In this study, we determined the potential of endemic Salmonella infections to reduce the reproductive success of blue (Cyanistes caeruleus) and great (Parus major) tits by correlating eggshell infection with reproductive parameters. The fifth egg of each clutch was collected from nest boxes in 19 deciduous forest fragments. Out of the 101 sampled eggs, 7 Salmonella Typhimurium isolates were recovered. The low bacterial prevalence was reflected by a similarly low serological prevalence in the fledglings. In this study with a relatively small sample size, presence of Salmonella did not affect reproductive parameters (egg volume, clutch size, number of nestlings and number of fledglings), nor the health status of the fledglings. However, in order to clarify the impact on health and reproduction a larger number of samples have to be analyzed. Phage typing showed that the isolates belonged to the definitive phage types (DT) 193 and 99, and multi-locus variable number tandem repeat analysis (MLVA) demonstrated a high similarity among the tit isolates, but distinction to human isolates. These findings suggest the presence of passerine-adapted Salmonella strains in free-ranging tit populations with host pathogen co-existence.

The challenge of teaching undergraduates evidence-based veterinary medicine

The Royal College of Veterinary Surgeons now lists 'How to evaluate evidence' as a day one competence for newly qualified vets. In this article, representatives from each of the veterinary schools in the UK discuss how the challenge of delivering and assessing the concepts of evidence-based veterinary medicine in a crowded undergraduate curriculum can be met.

Epidemiology of Diabetes Mellitus among 193,435 Cats Attending Primary-Care Veterinary Practices in England

BACKGROUND

Diabetes mellitus (DM) is a common endocrine disease of cats. The prevalence of DM in cats in England is not well-defined.

HYPOTHESIS/OBJECTIVES

To estimate the prevalence and identify risk factors for DM in a large population of cats attending primary-care practices.

ANIMALS

A cohort of 193,563 cats in the VetCompass Programme attending 118 primary-care practices in England.

METHODS

Cross-sectional analysis of cohort clinical data. Data were extracted covering September 1st 2009 and August 31st 2014. Period prevalence of DM was calculated. Associations between risk factors and DM were assessed using logistic regression modelling.

RESULTS

Of 1,128 DM cases were identified among 194,563 cats (period prevalence 0.58%; 95% confidence interval [CI] 0.54-0.61). Multivariable modelling indicated that Tonkinese (OR 4.1; 95% CI 1.8-9.6; P = .001), Norwegian Forest (odds ratio [OR] 3.5; 95% CI 1.3-9.6; P = .001) and Burmese (OR 3.0; 95% CI 2.0-4.4; P < .001) cats had increased odds of DM compared with crossbred cats. DM odds increased as bodyweight categories increased above 4 kg (P < .001), as cats aged beyond 6 years old (P < .001) and in insured cats (OR 2.0; 95% CI 1.6-2.4; P < .001) but sex was not significantly associated with DM.

CONCLUSIONS AND CLINICAL IMPORTANCE

Diabetes mellitus is an important component of the primary-care practice caseload with 1-in-200 cats affected. An increased risk of DM in certain cat breeds supports a genetic predisposition. These results can guide future research and preventative healthcare.

Increased temperatures negatively affect Juniperus communis seeds: evidence from transplant experiments along a latitudinal gradient

With a distribution range that covers most of the Northern hemisphere, common juniper (Juniperus communis) has one of the largest ranges of all vascular plant species. In several regions in Europe, however, populations are decreasing in size and number due to failing recruitment. One of the main causes for this failure is low seed viability. Observational evidence suggests that this is partly induced by climate warming, but our mechanistic understanding of this effect remains incomplete. Here, we experimentally assess the influence of temperature on two key developmental phases during sexual reproduction, i.e. gametogenesis and fertilisation (seed phase two, SP2) and embryo development (seed phase three, SP3). Along a latitudinal gradient from southern France to central Sweden, we installed a transplant experiment with shrubs originating from Belgium, a region with unusually low juniper seed viability. Seeds of both seed phases were sampled during three consecutive years, and seed viability assessed. Warming temperatures negatively affected the seed viability of both SP2 and SP3 seeds along the latitudinal gradient. Interestingly, the effect on embryo development (SP3) only occurred in the third year, i.e. when the gametogenesis and fertilisation also took place in warmer conditions. We found strong indications that this negative influence mostly acts via disrupting growth of the pollen tube, the development of the female gametophyte and fertilisation (SP2). This, in turn, can lead to failing embryo development, for example, due to nutritional problems. Our results confirm that climate warming can negatively affect seed viability of juniper.

Interacting effects of warming and drought on regeneration and early growth of Acer pseudoplatanus and A. platanoides

Climate change is acting on several aspects of plant life cycles, including the sexual reproductive stage, which is considered amongst the most sensitive life-cycle phases. In temperate forests, it is expected that climate change will lead to a compositional change in community structure due to changes in the dominance of currently more abundant forest tree species. Increasing our understanding of the effects of climate change on currently secondary tree species recruitment is therefore important to better understand and forecast population and community dynamics in forests. Here, we analyse the interactive effects of rising temperatures and soil moisture reduction on germination, seedling survival and early growth of two important secondary European tree species, Acer pseudoplatanus and A. platanoides. Additionally, we analyse the effect of the temperature experienced by the mother tree during seed production by collecting seeds of both species along a 2200-km long latitudinal gradient. For most of the responses, A. platanoides showed higher sensitivity to the treatments applied, and especially to its joint manipulation, which for some variables resulted in additive effects while for others only partial compensation. In both species, germination and survival decreased with rising temperatures and/or soil moisture reduction while early growth decreased with declining soil moisture content. We conclude that although A. platanoides germination and survival were more affected after the applied treatments, its initial higher germination and larger seedlings might allow this species to be relatively more successful than A. pseudoplatanus in the face of climate change.

Negative effects of temperature and atmospheric depositions on the seed viability of common juniper (Juniperus communis)

BACKGROUND AND AIMS

Environmental change is increasingly impacting ecosystems worldwide. However, our knowledge about the interacting effects of various drivers of global change on sexual reproduction of plants, one of their key mechanisms to cope with change, is limited. This study examines populations of poorly regenerating and threatened common juniper (Juniperus communis) to determine the influence of four drivers of global change (rising temperatures, nitrogen deposition, potentially acidifying deposition and altering precipitation patterns) on two key developmental phases during sexual reproduction, gametogenesis and fertilization (seed phase two, SP2) and embryo development (seed phase three, SP3), and on the ripening time of seeds.

METHODS

In 42 populations throughout the distribution range of common juniper in Europe, 11,943 seeds of two developmental phases were sampled. Seed viability was determined using seed dissection and related to accumulated temperature (expressed as growing degree-days), nitrogen and potentially acidifying deposition (nitrogen plus sulfur), and precipitation data.

KEY RESULTS

Precipitation had no influence on the viability of the seeds or on the ripening time. Increasing temperatures had a negative impact on the viability of SP2 and SP3 seeds and decreased the ripening time. Potentially acidifying depositions negatively influenced SP3 seed viability, while enhanced nitrogen deposition led to lower ripening times.

CONCLUSIONS

Higher temperatures and atmospheric deposition affected SP3 seeds more than SP2 seeds. However, this is possibly a delayed effect as juniper seeds develop practically independently, due to the absence of vascular communication with the parent plant from shortly after fertilization. It is proposed that the failure of natural regeneration in many European juniper populations might be attributed to climate warming as well as enhanced atmospheric deposition of nitrogen and sulfur.

1306-km 20x124.8-Gb/s PM-64QAM transmission over PSCF with net SEDP 11,300 (b ∙ km)/s/Hz using 1.15 samp/symb DAC

We demonstrated the transmission of a Nyquist-WDM signal based on PM-64QAM modulation in an EDFA-only submarine configuration composed of 54.4 km-long fiber spans: 20 channels at 124.8-Gb/s were propagated over 1306 km of low-loss pure-silica-core fiber (PSCF). Thanks to an aggressive digital spectral shaping, we achieved a raw spectral efficiency (SE) of 10.4 b/s/Hz, corresponding to 8.67 b/s/Hz net SE when considering a 20% FEC overhead. Transmitter DACs are operated at a record-low 1.15 samples/symbol, enabled by the insertion of advanced anti-alias filters. The achieved SE-times-distance product was 11,327 (b ∙ km)/(s ∙ Hz), the highest reported so far for PM-64QAM. Combining the experimental results with the performance predictions obtained using an analytical model of nonlinear propagation in uncompensated coherent optical systems (the so-called "GN-model"), we show that PM-64QAM is a realistic option for ultra-high capacity systems in the 1,000 km range, carrying up 40 Tb/s in the C-band.

Critical phases in the seed development of common juniper (Juniperus communis)

Common juniper (Juniperus communis L.) populations in northwest European lowlands are currently declining in size and number. An important cause of this decline is a lack of natural regeneration. Low seed viability seems to be one of the main bottlenecks in this process. Previous research revealed a negative relation between seed viability and both temperature and nitrogen deposition. Additionally, the seeds of common juniper have a variable ripening time, which possibly influences seed viability. However, the underlying mechanisms remain unresolved. In order to elucidate this puzzle, it is important to understand in which phases of seed production the main defects are situated, together with the influence of ripening time. In this study, we compared seed viability of populations with and without successful recruitment. We examined three seed phases: (i) gamete development; (ii) fertilisation and early-embryo development; and (iii) late-embryo development. After the first two phases, we found no difference in the percentage viable seeds between populations with or without recruitment. After late-embryo development, populations without recruitment showed a significantly lower percentage of viable seeds. These results suggest that late-embryo development is a bottleneck in seed development. However, the complex interaction between seed viability and ripening time suggest that the causes should be in the second seed phase, as the accelerated development of male and female gametophytes may disturb the male-female synchrony for successful mating.

A latitudinal gradient in seed nutrients of the forest herb Anemone nemorosa

The nutrient concentration in seeds determines many aspects of potential success of the sexual reproductive phase of plants, including the seed predation probability, efficiency of seed dispersal and seedling performance. Despite considerable research interest in latitudinal gradients of foliar nutrients, a similar gradient for seeds remains unexplored. We investigated a potential latitudinal gradient in seed nutrient concentrations within the widespread European understorey forest herb Anemone nemorosa L. We sampled seeds of A. nemorosa in 15 populations along a 1900-km long latitudinal gradient at three to seven seed collection dates post-anthesis and investigated the relative effects of growing degree-hours >5 °C, soil characteristics and latitude on seed nutrient concentrations. Seed nitrogen, nitrogen:phosphorus ratio and calcium concentration decreased towards northern latitudes, while carbon:nitrogen ratios increased. When taking differences in growing degree-hours and measured soil characteristics into account and only considering the most mature seeds, the latitudinal decline remained particularly significant for seed nitrogen concentration. We argue that the decline in seed nitrogen concentration can be attributed to northward decreasing seed provisioning due to lower soil nitrogen availability or greater investment in clonal reproduction. This pattern may have large implications for the reproductive performance of this forest herb as the degree of seed provisioning ultimately co-determines seedling survival and reproductive success.

Gender differences in bone turnover in 2-year-old Thoroughbreds

REASONS FOR PERFORMING STUDY

Injuries to the skeleton are a major cause of morbidity and mortality in racehorses and age, gender and season have all been shown to influence risk of injury.

OBJECTIVES

To use biochemical markers of bone cell activity to establish to whether cellular processes in bone underlie these described effects.

METHODS

Blood samples were collected monthly from 2-year-old horses in race training between November 1998 and September 1999. Mean age at the start of the study was 20 months (range 18-23 months), with no significant difference in average age between colts (n = 84) and fillies (n = 63). Three markers were measured; osteocalcin (OC, bone formation), the carboxyterminal cross-linked telopeptide of type I collagen (ICTP, bone resorption) and the carboxyterminal propeptide of type I collagen (PICP), which is less 'bone-specific' than the other 2 markers.

RESULTS

Colts had, on average, 3.62 ng/ml higher OC concentrations (P = 0.044) and 0.68 mg/l higher ICTP concentrations (P = 0.01) than fillies. The effect of gender was not statistically significant for PICP. However, in May, PICP concentrations were on average 157 mg/l higher in fillies than colts. There was no effect of age or season on marker concentrations.

CONCLUSIONS

This study has shown that there are gender differences in bone turnover markers in 2-year-old Thoroughbreds; however, age, within the limited range studied, did not have a significant effect on bone cell activity. Lower bone marker concentrations may reflect smaller bone size and/or earlier skeletal maturation in fillies. An increase in concentrations of PICP in fillies in spring and early summer may relect an influence of sex hormones on collagen turnover.

POTENTIAL RELEVANCE

Gender differences in bone cell activity in 2-year-old colts and fillies may influence bone's adaptive responses to training and risk of injury.

The effect of conformation on orthopaedic health and performance in a cohort of National Hunt racehorses: preliminary results

REASONS FOR PERFORMING STUDY

There is a lack of scientific data and studies on the effect of conformation on performance or on orthopaedic health.

OBJECTIVES

To investigate the relationship between conformation, injury and performance in racehorses used for racing over fences.

METHODS

Over 2 years, 108 National Hunt racehorses were followed and their medical and performance data recorded. Conformation was measured in 3D with a computerised motion analysis system. Linear multiple regression models were used to evaluate the effect of conformation on measures of race performance and stepwise forward logistic regression models to assess the effect on risk of injury.

RESULTS

An increase in intermandibular width, flexor angle of the shoulder joint and coxal angle (the angle between the ilium and ischium) was demonstrated to have a positive effect on performance. Performance decreased with increasing girth, length of the hind digit and valgus conformation of the metacarpophalangeal joint. The risk of suffering from superficial digital flexor tendon injury increased with increasing metacarpophalangeal joint angle and with carpus valgus conformation. The risk of pelvic fracture increased with valgus conformation of the tarsus and decreased with an increasing coxal angle.

CONCLUSION

Valgus deformation was demonstrated to be detrimental to performance or increased risk of injury, perhaps resulting in higher loads on musculoskeletal structures. The coxal angle was the only parameter to have an effect on both risk of injury and performance. An alignment of the muscles with the axis of the pelvis may be beneficial for force transmission and decrease the bending moment of the muscles on the bones. The statistical power of this study is limited, however it provides preliminary data necessary for the planning of a larger scale study on the effect of conformation on performance and risk of injury.

CLINICAL RELEVANCE

Studies of the effects of conformation on performance and risk of injury may aid in identifying individuals likely to perform well on the racecourse and avoid risks of injury.

Juniperus communis: victim of the combined action of climate warming and nitrogen deposition?

Research on the combined effects of climate change and nitrogen deposition on reproductive traits, and especially on the production of viable seeds, is still scarce despite their importance for population persistence and expansion. Hence, in this study we set out to investigate the direct and indirect effects of the above-mentioned global change drivers on seed viability in the coniferous shrub Juniperus communis L. In many parts of its European range, juniper is increasingly threatened, partly because of a lack of sexual reproduction. We hypothesised that this regeneration failure is partly due to poor seed viability. Using data from 39 populations throughout Europe, we were able to demonstrate that a strong, triangular-shaped relationship exists between the percentage of viable seeds produced and the percentage of juniper seedlings occurring in a population, which indicates that the species is indeed partly seed limited. Furthermore, based on an extended dataset of 42 populations, we found that seed viability was negatively affected by temperature, measured as mean annual growing degree-days, and nitrogen deposition (but not by drought). Suggestions are made about the processes behind the observed patterns, but more research is required. Nevertheless, our results do raise serious concerns for the conservation of juniper in light of the predicted rise in temperature and global nitrogen emissions. Furthermore, it is likely that similar patterns can also be observed for other species.

Effect of vegetation type on throughfall deposition and seepage flux

This paper compares different vegetation types (coniferous and deciduous forest, grassed and pure heathland) in terms of input (throughfall deposition) and output (seepage flux) in a region with intermediate nitrogen load (+/-20kg Nha(-1)y(-1) via bulk precipitation) in comparable conditions in north Belgium. Coniferous forest (two plots Pinus sylvestris and two plots Pinus nigra) received significantly higher nitrogen and sulphur throughfall deposition than deciduous forest and heathland. Grassed and pure heathland had significantly highest throughfall quantities of Ca(2+) and Mg(2+), respectively. The observed differences in throughfall deposition between the different vegetation types were not univocally reflected in the ion seepage flux. Considerable seepage fluxes of NO(3)(-), SO(4)(2-), Ca(2+) and Al(III) were only found under the P. nigra plots. We discuss our hypothesis that the P. nigra forests already evolved to a situation of N saturation, while the other vegetation types did not.

Control of strangles outbreaks by isolation of guttural pouch carriers identified using PCR and culture of Streptococcus equi

Previous use of repeated nasopharyngeal swabbing and culture of Streptococcus equi showed that healthy carriers developed in more than 50% of 'strangles' outbreaks. The guttural pouches were the only detectable site of S. equi colonisation on endoscopic examination of horses during one of these outbreaks and S. equi was sometimes not detected by culture of nasopharyngeal swabs from carriers for up to 2 or 3 months before nasal shedding resumed sporadically. A more sensitive way of detecting S. equi on swabs from established guttural pouch carriers was therefore required. Conveniently selected 'strangles' outbreaks were investigated in detail using endoscopy, in order to develop and assess a suitable polymerase chain reaction (PCR) test. We report here 3 protracted 'strangles' outbreaks on different kinds of establishments in which between 29 and 52% of sampled horses were infected as detected by culture and/or PCR. Of the infected horses, between 9 and 44% were identified as carrying S. equi after clinical signs had disappeared and the predominant site of carriage was the guttural pouch. Prolonged carriage of S. equi, which lasted up to 8 months, did not cease spontaneously before treatment was initiated to eliminate the infections. The detection and isolation of the carriers, in conjunction with strict hygiene measures, apparently resulted in the control of the outbreaks and allowed the premises to return to normal activity. Comparing PCR and culture, many more swabs were found to be positive using PCR (56 vs. 30% of 61 swabs). Similar results were obtained for guttural pouch samples from 12 established carriers (PCR 76% and culture 59%). These results from repeated samples from relatively few animals need confirming using more long-term carriers. PCR can also detect dead organisms and is, therefore, liable to yield false positive results. Despite this drawback, it is argued that PCR provides a potentially useful adjunct to culture of nasopharyngeal swabs in the detection of asymptomatic carriers of S. equi following outbreaks of 'strangles'.

Elimination of guttural pouch infection and inflammation in asymptomatic carriers of Streptococcus equi

Three protracted outbreaks of strangles were investigated using endoscopic examination and a total of 14 asymptomatic carriers of Streptococcus equi were identified of which 13 showed evidence of carriage in the guttural pouch. Treatment was initiated to eliminate S. equi colonisation since these animals posed an infectious risk to susceptible horses. Two further horses were referred to us with severe guttural pouch pathology and from which S. equi was cultured, and treatment of these cases is also described. Treatment in the first instance was directed towards removal of gross guttural pouch pathology as seen on endoscopic examination. This was done with a combination of irrigation of the pouch with moderate to large amounts of saline, suction of fluid material and endoscopic manipulation of chondroids. Subsequently, antibiotic treatment was used to eliminate S. equi infection. All animals received systemic antibiotics, in some cases combined with topical antimicrobial treatment. Treatment was generally regarded as successful when the guttural pouches appeared normal and S. equi was not detected in nasopharangeal swabs and pouch lavages on 3 consecutive occasions. Successful treatment of one carrier required surgical intervention due to occlusion of both guttural pouch pharyngeal openings. Fourteen of 15 carriers were successfully treated by endoscopic removal of inflammatory material and antibiotic treatment, without surgical intervention. Five carriers originally given potentiated sulphonamide (33%) required further therapy with penicillin or ceftiofur, administered both systemically and topically, before S. equi infection and associated inflammation of the guttural pouches were eliminated.

Equine influenza in the United Kingdom in 1998

In 1998, equine influenza was diagnosed by serology and nucleoprotein enzyme-linked immunosorbent assay as the cause of acute respiratory disease in vaccinated and unvaccinated horses in the UK. The signs were generally milder in vaccinated horses and completely susceptible animals showed the most severe signs, including pyrexia, inappetence, coughing, mucopurulent nasal discharge and secondary bacterial pneumonia. In a detailed investigation of an outbreak among 52 vaccinated thoroughbreds in a flat racing yard, more than 60 per cent of the horses seroconverted on the evidence of paired serum samples tested by single radial haemolysis (SRH). Preliminary sequencing and characterisation of an isolate from this outbreak indicated that it was an 'American-like' strain. In addition, in this outbreak there was a larger proportion of horses with preinfection SRH titres greater than 140 mm2 that subsequently seroconverted than in other recent outbreaks from which 'European-like' strains have been isolated. This result suggested that the cross-protectivity between circulating 'American-like' strains and the 'European-like' strains of A/equine-2 viruses present in current vaccines may be decreasing.

In vitro expression of alpha-L-fucosidase activity polymorphism observed in plasma

Several quantitative and qualitative characteristics of alpha-L-fucosidase were studied in cultured skin fibroblasts derived from variant and non-variant individuals. In comparison with non-variant cultures with similar growth characteristics, the intracellular level of alpha-L-fucosidase was specifically reduced by at least 50% at all stages of the culture cycle. The amount of enzyme released into the growth medium was also decreased, but the ratio of the extracellular enzyme to the total enzyme activity produced, was not significantly different from that in non-variant cultures. pH-dependence, apparent Km value and temperature sensitivity of the variant alpha-L-fucosidase were identical to that of the enzyme in non-variant cells. Specific differences between the variant and non-variant enzyme were consistently observed upon enzyme inactivation at acid pH and in thermostabilisation studies with NaCl. The DEAE elution profiles and pH-dependent association patterns obtained by ultracentrifugation were also different for both types of intracellular alpha-L-fucosidase. It is concluded that the quantitative as well as the qualitative differences of alpha-L-fucosidase characteristics found in variant fibroblasts are the in vitro expression of the variant genotype, already phenotypically observed in human plasma.