Simulating long-term wildfire impacts on boreal forest structure in Central Yakutia, Siberia, since the Last Glacial Maximum

Background

Wildfires are recognized as an important ecological component of larch-dominated boreal forests in eastern Siberia. However, long-term fire-vegetation dynamics in this unique environment are poorly understood. Recent paleoecological research suggests that intensifying fire regimes may induce millennial-scale shifts in forest structure and composition. This may, in turn, result in positive feedback on intensifying wildfires and permafrost degradation, apart from threatening human livelihoods. Most common fire-vegetation models do not explicitly include detailed individual-based tree population dynamics, but a focus on patterns of forest structure emerging from interactions among individual trees may provide a beneficial perspective on the impacts of changing fire regimes in eastern Siberia. To simulate these impacts on forest structure at millennial timescales, we apply the individual-based, spatially explicit vegetation model LAVESI-FIRE, expanded with a new fire module. Satellite-based fire observations along with fieldwork data were used to inform the implementation of wildfire occurrence and adjust model parameters.

Results

Simulations of annual forest development and wildfire activity at a study site in the Republic of Sakha (Yakutia) since the Last Glacial Maximum (c. 20,000 years BP) highlight the variable impacts of fire regimes on forest structure throughout time. Modeled annual fire probability and subsequent burned area in the Holocene compare well with a local reconstruction of charcoal influx in lake sediments. Wildfires can be followed by different forest regeneration pathways, depending on fire frequency and intensity and the pre-fire forest conditions. We find that medium-intensity wildfires at fire return intervals of 50 years or more benefit the dominance of fire-resisting Dahurian larch (Larix gmelinii (Rupr.) Rupr.), while stand-replacing fires tend to enable the establishment of evergreen conifers. Apart from post-fire mortality, wildfires modulate forest development mainly through competition effects and a reduction of the model's litter layer.

Conclusion

With its fine-scale population dynamics, LAVESI-FIRE can serve as a highly localized, spatially explicit tool to understand the long-term impacts of boreal wildfires on forest structure and to better constrain interpretations of paleoecological reconstructions of fire activity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42408-023-00238-8.

Evolutionary adaptation of trees and modelled future larch forest extent in Siberia

With changing climate, the boreal forest could potentially migrate north and become threatened by droughts in the south. However, whether larches, the dominant tree species in eastern Siberia, can adapt to novel situations is largely unknown but is crucial for predicting future population dynamics. Exploring variable traits and trait adaptation through inheritance in an individual-based model can improve our understanding and help future projections. We updated the individual-based spatially explicit vegetation model LAVESI (Larix Vegetation Simulator), used for forest predictions in Eastern Siberia, with trait value variation and incorporated inheritance of parental values to their offspring. Forcing the model with both past and future climate projections, we simulated two areas - the expanding northern treeline and a southerly area experiencing drought. While the specific trait of 'seed weight' regulates migration, the abstract 'drought resistance' protects stands. We show that trait variation with inheritance leads to an increase in migration rate (∼ 3% area increase until 2100). The drought resistance simulations show that, under increasing stress, including adaptive traits leads to larger surviving populations (17% of threatened under RCP 4.5 (Representative Concentration Pathway)). We show that with the increase expected under the RCP 8.5 scenario vast areas (80% of the extrapolated area) of larch forest are threatened and could disappear due to drought as adaptation plays only a minor role under strong warming. We conclude that variable traits facilitate the availability of variants under environmental changes. Inheritance allows populations to adapt to environments and promote successful traits, which leads to populations that can spread faster and be more resilient, provided the changes are not too drastic in both time and magnitude. We show that trait variation and inheritance contribute to more accurate models that can improve our understanding of responses of boreal forests to global change.

Holocene wildfire and vegetation dynamics in Central Yakutia, Siberia, reconstructed from lake-sediment proxies

Wildfires play an essential role in the ecology of boreal forests. In eastern Siberia, fire activity has been increasing in recent years, challenging the livelihoods of local communities. Intensifying fire regimes also increase disturbance pressure on the boreal forests, which currently protect the permafrost beneath from accelerated degradation. However, long-term relationships between changes in fire regime and forest structure remain largely unknown. We assess past fire-vegetation feedbacks using sedimentary proxy records from Lake Satagay, Central Yakutia, Siberia, covering the past c. 10,800 years. Results from macroscopic and microscopic charcoal analyses indicate high amounts of burnt biomass during the Early Holocene, and that the present-day, low-severity surface fire regime has been in place since c. 4,500 years before present. A pollen-based quantitative reconstruction of vegetation cover and a terrestrial plant record based on sedimentary ancient DNA metabarcoding suggest a pronounced shift in forest structure toward the Late Holocene. Whereas the Early Holocene was characterized by postglacial open larch-birch woodlands, forest structure changed toward the modern, mixed larch-dominated closed-canopy forest during the Mid-Holocene. We propose a potential relationship between open woodlands and high amounts of burnt biomass, as well as a mediating effect of dense larch forest on the climate-driven intensification of fire regimes. Considering the anticipated increase in forest disturbances (droughts, insect invasions, and wildfires), higher tree mortality may force the modern state of the forest to shift toward an open woodland state comparable to the Early Holocene. Such a shift in forest structure may result in a positive feedback on currently intensifying wildfires. These new long-term data improve our understanding of millennial-scale fire regime changes and their relationships to changes of vegetation in Central Yakutia, where the local population is already being confronted with intensifying wildfire seasons.

Modern Pollen Assemblages From Lake Sediments and Soil in East Siberia and Relative Pollen Productivity Estimates for Major Taxa

Modern pollen–vegetation–climate relationships underpin palaeovegetation and palaeoclimate reconstructions from fossil pollen records. East Siberia is an ideal area for investigating the relationships between modern pollen assemblages and near natural vegetation under cold continental climate conditions. Reliable pollen-based quantitative vegetation and climate reconstructions are still scarce due to the limited number of modern pollen datasets. Furthermore, differences in pollen representation of samples from lake sediments and soils are not well understood. Here, we present a new pollen dataset of 48 moss/soil and 24 lake surface-sediment samples collected in Chukotka and central Yakutia in East Siberia. The pollen–vegetation–climate relationships were investigated by ordination analyses. Generally, tundra and taiga vegetation types can be well distinguished in the surface pollen assemblages. Moss/soil and lake samples contain generally similar pollen assemblages as revealed by a Procrustes comparison with some exceptions. Overall, modern pollen assemblages reflect the temperature and precipitation gradients in the study areas as revealed by constrained ordination analysis. We estimate the relative pollen productivity (RPP) of major taxa and the relevant source area of pollen (RSAP) for moss/soil samples from Chukotka and central Yakutia using Extended R-Value (ERV) analysis. The RSAP of the tundra-forest transition area in Chukotka and taiga area in central Yakutia are ca. 1300 and 360 m, respectively. For Chukotka, RPPs relative to both Poaceae and Ericaceae were estimated while RPPs for central Yakutia were relative only to Ericaceae. Relative to Ericaceae (reference taxon, RPP = 1), Larix, Betula, Picea, and Pinus are overrepresented while Alnus, Cyperaceae, Poaceae, and Salix are underrepresented in the pollen spectra. Our estimates are in general agreement with previously published values and provide the basis for reliable quantitative reconstructions of East Siberian vegetation.

Regional opportunities for tundra conservation in the next 1000 years

The biodiversity of tundra areas in northern high latitudes is threatened by invasion of forests under global warming. However, poorly understood nonlinear responses of the treeline ecotone mean the timing and extent of tundra losses are unclear, but policymakers need such information to optimize conservation efforts. Our individual-based model LAVESI, developed for the Siberian tundra-taiga ecotone, can help improve our understanding. Consequently, we simulated treeline migration trajectories until the end of the millennium, causing a loss of tundra area when advancing north. Our simulations reveal that the treeline follows climate warming with a severe, century-long time lag, which is overcompensated by infilling of stands in the long run even when temperatures cool again. Our simulations reveal that only under ambitious mitigation strategies (relative concentration pathway 2.6) will ∼30% of original tundra areas remain in the north but separated into two disjunct refugia.

Interspecies metabolite transfer and aggregate formation in a co-culture of Dehalococcoides and Sulfurospirillum dehalogenating tetrachloroethene to ethene

Microbial communities involving dehalogenating bacteria assist in bioremediation of areas contaminated with halocarbons. To understand molecular interactions between dehalogenating bacteria, we co-cultured Sulfurospirillum multivorans, dechlorinating tetrachloroethene (PCE) to cis-1,2-dichloroethene (cDCE), and Dehalococcoides mccartyi strains BTF08 or 195, dehalogenating PCE to ethene. The co-cultures were cultivated with lactate as electron donor. In co-cultures, the bacterial cells formed aggregates and D. mccartyi established an unusual, barrel-like morphology. An extracellular matrix surrounding bacterial cells in the aggregates enhanced cell-to-cell contact. PCE was dehalogenated to ethene at least three times faster in the co-culture. The dehalogenation was carried out via PceA of S. multivorans, and PteA (a recently described PCE dehalogenase) and VcrA of D. mccartyi BTF08, as supported by protein abundance. The co-culture was not dependent on exogenous hydrogen and acetate, suggesting a syntrophic relationship in which the obligate hydrogen consumer D. mccartyi consumes hydrogen and acetate produced by S. multivorans. The cobamide cofactor of the reductive dehalogenase-mandatory for D. mccartyi-was also produced by S. multivorans. D. mccartyi strain 195 dechlorinated cDCE in the presence of norpseudo-B₁₂ produced by S. multivorans, but D. mccartyi strain BTF08 depended on an exogenous lower cobamide ligand. This observation is important for bioremediation, since cofactor supply in the environment might be a limiting factor for PCE dehalogenation to ethene, described for D. mccartyi exclusively. The findings from this co-culture give new insights into aggregate formation and the physiology of D. mccartyi within a bacterial community.

Sedimentary ancient DNA reveals a threat of warming-induced alpine habitat loss to Tibetan Plateau plant diversity

Studies along elevational gradients worldwide usually find the highest plant taxa richness in mid-elevation forest belts. Hence, an increase in upper elevation diversity is expected in the course of warming-related treeline rise. Here, we use a time-series approach to infer past taxa richness from sedimentary ancient DNA from the south-eastern Tibetan Plateau over the last ~18,000 years. We find the highest total plant taxa richness during the cool phase after glacier retreat when the area contained extensive and diverse alpine habitats (14-10 ka); followed by a decline when forests expanded during the warm early- to mid-Holocene (10-3.6 ka). Livestock grazing since 3.6 ka promoted plant taxa richness only weakly. Based on these inferred dependencies, our simulation yields a substantive decrease in plant taxa richness in response to warming-related alpine habitat loss over the next centuries. Accordingly, efforts of Tibetan biodiversity conservation should include conclusions from palaeoecological evidence.

Long-lived larch clones may conserve adaptations that could restrict treeline migration in northern Siberia

The occurrence of refugia beyond the arctic treeline and genetic adaptation therein play a crucial role of largely unknown effect size. While refugia have potential for rapidly colonizing the tundra under global warming, the taxa may be maladapted to the new environmental conditions. Understanding the genetic composition and age of refugia is thus crucial for predicting any migration response. Here, we genotype 194 larch individuals from an ~1.8 km2 area in northcentral Siberia on the southern Taimyr Peninsula by applying an assay of 16 nuclear microsatellite markers. For estimating the age of clonal individuals, we counted tree rings at sections along branches to establish a lateral growth rate that was then combined with geographic distance. Findings reveal that the predominant reproduction type is clonal (58.76%) by short distance spreading of ramets. One outlier of clones 1 km apart could have been dispersed by reindeer. In clonal groups and within individuals, we find that somatic mutations accumulate with geographic distance. Clonal groups of two or more individuals are observed. Clonal age estimates regularly suggest individuals as old as 2,200 years, which coincides with a major environmental change that forced a treeline retreat in the region. We conclude that individuals with clonal growth mode were naturally selected as it lowers the likely risk of extinction under a harsh environment. We discuss this legacy from the past that might now be a maladaptation and hinder expansion under currently strongly increasing temperatures.

OP0104 THE IMPACT OF PERSISTENT INFLAMMATORY CHANGES ON PREVALENCE OF FATTY LESIONS IN PATIENTS WITH AXIAL SPONDYLOARTHRITIS TREATED WITH CERTOLIZUMAB PEGOL: 4-YEAR MRI RESULTS FROM RAPID-AXSPA

Background:

Axial spondyloarthritis (axSpA) is a chronic disease characterised by inflammation in the sacroiliac joints and spine, causing severe back pain and stiffness. Emerging evidence suggests chronic spinal inflammation may be associated with osteoproliferation leading to syndesmophyte formation and spinal ankylosis, with subsequent worsening of patient mobility and function.1Fatty lesions (FLs) on magnetic resonance imaging (MRI) T1 sequences are considered to be post-inflammatory precursors to these changes. Certolizumab pegol (CZP), an Fc-free, PEGylated tumour necrosis factor inhibitor (TNFi), has proven efficacy in treating the signs and symptoms of axSpA.2,3CZP has also been shown to decrease spinal and sacroiliac joint MRI inflammation, and limit radiographic progression of the spine over 4 years of treatment.4

Objectives:

To report the effect of early post-baseline (BL) inflammatory changes on fatty lesion prevalence over 4 years in a broad axSpA patient population treated with CZP.

Methods:

RAPID-axSpA (NCT01087762) was a phase 3 trial which was double-blind and placebo (PBO)-controlled to Week (Wk) 24, dose-blind to Wk 48 and open-label to Wk 204. CZP-randomised axSpA patients (Wk 0 CZP: 200 mg every 2 wks [Q2W] or 400 mg Q4W) continued their assigned dose throughout; PBO-randomised axSpA patients (Wk 0 PBO) received CZP from Wk 24, or if non-responders, from Wk 16 onwards. Blinded spinal MRI scans at Wks 0, 12, 48, 96 and 204 were assessed by 2 central readers to evaluate FL and inflammatory lesions in vertebral edges (VEs). Changes in FL prevalence are reported as odds ratios (OR; FL+/FL-) between time points or inflammation states, with nominal 95% confidence intervals (CI), for Wk 0 CZP. ORs were estimated from a logistic regression model for VE level data with random effects for patient and VE (within patient). The fixed model effects included time point, inflammatory status of VEs at BL and Wk 12, FL status at BL, and interactions if appropriate.

Results:

Of 325 axSpA patients, 89 and 47 initially randomised to CZP or PBO, respectively, had a BL and ≥1 post-BL MRI and therefore were eligible for these analyses. In these patients, a total of 3,127 of VEs were assessed at BL; inflammation was observed in 21.6% and FL in 29.3% of VEs, equating to mean counts of 5.0 and 6.7 per patient; 10.5% of VEs had both inflammation and FL at BL. At BL, FLs were relatively more often observed in inflamed VEs vs non-inflamed VEs: OR (95% CI) of 3.30 (1.94, 5.61). This difference increased over time, as the OR of FL at Wk 204 vs BL was 2.82 (1.70, 4.66) in VEs that were inflamed at BL compared with 1.08 (0.79, 1.48) in VEs that were not inflamed at BL (Figure 1A). Resolution of inflammation by Wk 12 appeared to lower the risk of FL prevalence over 4 years. When adjusted for BL VE status with respect to inflammation and FL, if inflammation prevailed at Wk 12, the OR of FL vs no FL was 1.80 (0.93, 3.49) at Wk 48, 2.54 (1.32, 4.91) at Wk 96 and 3.91 (1.87, 8.15) at Wk 204 (Figure 1B).

Conclusion:

This is the first report from a clinical interventional PBO-controlled study in a broad axSpA population showing that inflammation that prevailed after the start of TNFi treatment was associated with increased FL prevalence over 4 years. Reduction of inflammation by Wk 12 mitigated the risk of FL over the long-term, indicating the importance of early, effective and long-term treatment targeting inflammation. Similarly, a complete and persistent reduction of inflammation appears to be critical in these patients.

References:

[1]Maksymowych WP. Ann Rheum Dis 2013;72:23–8;2.Van der Heijde D. Rheumatology (Oxford) 2017;56:1498–509;3.Deodhar A. Arthritis Rheumatol 2019;71:1101–11;4.Van der Heijde D. Ann Rheum Dis 2018;77:699–705.

Acknowledgments:

This study was funded by UCB Pharma. Editorial services were provided by Costello Medical.

Disclosure of Interests:

Xenofon Baraliakos Grant/research support from: Grant/research support from: AbbVie, BMS, Celgene, Chugai, Merck, Novartis, Pfizer, UCB and Werfen, Consultant of: AbbVie, BMS, Celgene, Chugai, Merck, Novartis, Pfizer, UCB and Werfen, Speakers bureau: AbbVie, BMS, Celgene, Chugai, Merck, Novartis, Pfizer, UCB and Werfen, Sebastian Kruse: None declared, Simone Auteri Shareholder of: UCB Pharma, Employee of: UCB Pharma, Natasha de Peyrecave Employee of: UCB Pharma, Tommi Nurminen Employee of: UCB Pharma, Thomas Kumke Employee of: UCB Pharma, Bengt Hoepken Employee of: UCB Pharma, Juergen Braun Grant/research support from: Abbvie (Abbott), Amgen, BMS, Boehringer, Celgene, Celltrion, Centocor, Chugai, Eli Lilly and Company, Medac, MSD (Schering Plough), Mundipharma, Novartis, Pfizer (Wyeth), Roche, Sanofi- Aventis, and UCB Pharma, Consultant of: Abbvie (Abbott), Amgen, BMS, Boehringer, Celgene, Celltrion, Centocor, Chugai, EBEWE Pharma, Eli Lilly and Company, Medac, MSD (Schering-Plough), Mundipharma, Novartis, Pfizer (Wyeth), Roche, Sanofi-Aventis, and UCB Pharma, Speakers bureau: Abbvie (Abbott), Amgen, BMS, Boehringer, Celgene, Celltrion, Centocor, Chugai, EBEWE Pharma, Eli Lilly and Company, Medac, MSD (Schering-Plough), Mundipharma, Novartis, Pfizer (Wyeth), Roche, Sanofi-Aventis, and UCB Pharma

[Usability and Efficiency of a Digital Communication Assistance Tool to Obtain Medical History from Non-German-Speaking Patients]

AIM

In the DICTUM-Friedland study, a medical history-taking app was implemented in an initial reception facility for refugees and asylum seekers. This app can be used to obtain from patients information about the most frequent general medical complaints and risk factors in 13 different languages or dialects. A report (synopsis) is generated, based on each patient's given data, in the German language. Usability and efficiency of obtaining medical history were the criteria evaluated in order to test and optimize the app for use in a broader general medical setting.

METHODS

From May to December 2018, the app was tested in the waiting room of the general medical ward in the refugee camp in Friedland in southern Lower Saxony, Germany. Patients were asked to complete a short digital questionnaire about the usability of the app immediately after finishing the query. Sociodemographic data were partly collected with the same questionnaire and partly extracted from patient records. The efficiency was evaluated on the basis of the correspondence between the entered complaints (ICPC-2) and the diagnoses of the doctors (ICD-10).

RESULTS

In total, the app was used 353 times, and based on these, 283 medical histories were taken. The median time for entering the complaints was 10:27 minutes. The use of the audio output (60% of patients used this option) did not influence the usability. The majority of the users (76%) rated the app as easy to use and 65% of the users stated that they were able to enter their main complaints. Both assessments were independent of the age and sex of the users, but the educational level had a slightly more positive influence. The efficiency test showed that 51% (n=144) of the synopses matched fully and 28% (n=79) of the synopses matched partially with the medical diagnoses.

CONCLUSION

The systematic survey of the most frequent general medical complaints enables a more precise medical history taking in patients with whom a normal interview is not possible due to language barriers. Thus it serves as a support for the medical history taking. The app is easy to use and not prone to the errors of online translations.

A Digital Communication Assistance Tool (DCAT) toObtain Medical History from Foreign-LanguagePatients: Development and Pilot Testing in a PrimaryHealth Care Center for Refugees

Background: Language barriers play a critical role in the treatment of migrant and refugee patients. In Germany, primary care interpreters are often not available especially in rural areas or if patients demand spontaneous or urgent consultations. Methods: In order to enable patients and their physicians to communicate effectively about the current illness history, we developed a digital communication assistance tool (DCAT) for 19 different languages and dialects. This paper reports the multidisciplinary process of the conceptual design and the iterative development of this cross-cultural user-centered application in an action-oriented approach. Results: We piloted our app with 36 refugee patients prior to a clinical study and used the results for further development. The acceptance and usability of the app by patients was high. Conclusion: Using digital tools for overcoming language barriers can be a feasible approach when providing health care to foreign-language patients.

Models and evidence of intersectoral cooperation in prevention and health promotion

Background

Inter-sectoral coalitions are regarded as a key principle of health promotion. The study examines the questions of how these are defined, which scientific theories and models are available, and which methods and parameters are used for their evaluation.

Methods

The scoping review in three databases (PubMed, Web of Science, LIVIVO) included studies in English and German published in 1/2010 to 5/2018. The results were analyzed qualitatively. In addition, relevant websites and textbooks in the field of public health, health promotion and social work were subjected to a document analysis in an iterative procedure.

Results

The database searches yielded 186 hits, of which 48 publications were systematically examined. Document analysis revealed 128 materials. Six common terms on inter-sectoral cooperation (network, collaboration, partnership, coalition, cooperation, alliance) were identified. Uniform definitions and unambiguous distinctions do not exist. Overall, only a few of the identified inter-sectoral collaborations are theoretically based, nine publications present models. Only seven studies provide insights into the effectiveness of model/theory-based strategies, whereby these almost exclusively examine output parameters. In particular, there are parameters on structure and process (e.g. team functioning, coalition capacity). Qualitative success factors and barriers were identified (e.g. integration of different actors, development of new financial sources, formalization). Eight validated instruments are identified. Four studies also examine the outcome level and demonstrate intended effects on behavioral parameters.

Conclusions

For research and practice, it is necessary to sharpen the terminology of intersectoral cooperation. Existing models should be systematically used and evaluated. In the future, an evaluation of the outcome of inter-sectoral cooperation and long-term effects will be increasingly necessary.

Key messages

Inter-sectoral coalitions are an evolving field, and both their theoretical foundation and empirical testing are still in their infancy. While success factors are well investigated, evaluations at the outcomes level are particularly necessary.

Chloroplast and mitochondrial genetic variation of larches at the Siberian tundra-taiga ecotone revealed by de novo assembly

Larix populations at the tundra-taiga ecotone in northern Siberia are highly under-represented in population genetic studies, possibly due to the remoteness of these regions that can only be accessed at extraordinary expense. The genetic signatures of populations in these boundary regions are therefore largely unknown. We aim to generate organelle reference genomes for the detection of single nucleotide polymorphisms (SNPs) that can be used for paleogenetic studies. We present 19 complete chloroplast genomes and mitochondrial genomic sequences of larches from the southern lowlands of the Taymyr Peninsula (northernmost range of Larix gmelinii (Rupr.) Kuzen.), the lower Omoloy River, and the lower Kolyma River (both in the range of Larix cajanderi Mayr). The genomic data reveal 84 chloroplast SNPs and 213 putatively mitochondrial SNPs. Parsimony-based chloroplast haplotype networks show no spatial structure of individuals from different geographic origins, while the mitochondrial haplotype network shows at least a slight spatial structure with haplotypes from the Omoloy and Kolyma populations being more closely related to each other than to most of the haplotypes from the Taymyr populations. Whole genome alignments with publicly available complete chloroplast genomes of different Larix species show that among official plant barcodes only the rcbL gene contains sufficient polymorphisms, but has to be sequenced completely to distinguish the different provenances. We provide 8 novel mitochondrial SNPs that are putatively diagnostic for the separation of L. gmelinii and L. cajanderi, while 4 chloroplast SNPs have the potential to distinguish the L. gmelinii/L. cajanderi group from other Larix species. Our organelle references can be used for a targeted primer and probe design allowing the generation of short amplicons. This is particularly important with regard to future investigations of, for example, the biogeographic history of Larix by screening ancient sedimentary DNA of Larix.

Democracy Confused: When People Mistake the Absence of Democracy for Its Presence

A widely neglected phenomenon consists in the fact that large population segments in many countries confuse the absence of democracy with its presence. Significantly, these are also the countries where widespread support for democracy coexists with persistent deficiencies in the latter, including its outright absence. Addressing this puzzle, we introduce a framework to sort out to what extent national populations overestimate their regimes’ democratic qualities. We test our hypotheses applying multilevel models to about 93,000 individuals from 75 countries covered by the cross-cultural World Values Surveys. We find that overestimating democracy is a widespread phenomenon, although it varies systematically across countries. Among a multitude of plausible influences, cognitive stimuli and emancipative values work together as a psychologically activating force that turns people against overestimating democracy. In fact, this psychological activation not only reduces overestimations of democracy; it actually leads toward underestimations, thus increasing criticality rather than accuracy in assessments. We conclude that, by elevating normative expectations, psychological activation releases prodemocratic selection pressures in the evolution of regimes.

Guided cobamide biosynthesis for heterologous production of reductive dehalogenases

Cobamides (Cbas) are essential cofactors of reductive dehalogenases (RDases) in organohalide‐respiring bacteria (OHRB). Changes in the Cba structure can influence RDase function. Here, we report on the cofactor versatility or selectivity of Desulfitobacterium RDases produced either in the native organism or heterologously. The susceptibility of Desulfitobacterium hafniense strain DCB‐2 to guided Cba biosynthesis (i.e. incorporation of exogenous Cba lower ligand base precursors) was analysed. Exogenous benzimidazoles, azabenzimidazoles and 4,5‐dimethylimidazole were incorporated by the organism into Cbas. When the type of Cba changed, no effect on the turnover rate of the 3‐chloro‐4‐hydroxy‐phenylacetate‐converting enzyme RdhA6 and the 3,5‐dichlorophenol‐dehalogenating enzyme RdhA3 was observed. The impact of the amendment of Cba lower ligand precursors on RDase function was also investigated in Shimwellia blattae, the Cba producer used for the heterologous production of Desulfitobacterium RDases. The recombinant tetrachloroethene RDase (PceA_Y51) appeared to be non‐selective towards different Cbas. However, the functional production of the 1,2‐dichloroethane‐dihaloeliminating enzyme (DcaA) of Desulfitobacterium dichloroeliminans was completely prevented in cells producing 5,6‐dimethylbenzimidazolyl‐Cba, but substantially enhanced in cells that incorporated 5‐methoxybenzimidazole into the Cba cofactor. The results of the study indicate the utilization of a range of different Cbas by Desulfitobacterium RDases with selected representatives apparently preferring distinct Cbas.

Temporal and spatial patterns of mitochondrial haplotype and species distributions in Siberian larches inferred from ancient environmental DNA and modeling

Changes in species' distributions are classically projected based on their climate envelopes. For Siberian forests, which have a tremendous significance for vegetation-climate feedbacks, this implies future shifts of each of the forest-forming larch (Larix) species to the north-east. However, in addition to abiotic factors, reliable projections must assess the role of historical biogeography and biotic interactions. Here, we use sedimentary ancient DNA and individual-based modelling to investigate the distribution of larch species and mitochondrial haplotypes through space and time across the treeline ecotone on the southern Taymyr peninsula, which at the same time presents a boundary area of two larch species. We find spatial and temporal patterns, which suggest that forest density is the most influential driver determining the precise distribution of species and mitochondrial haplotypes. This suggests a strong influence of competition on the species' range shifts. These findings imply possible climate change outcomes that are directly opposed to projections based purely on climate envelopes. Investigations of such fine-scale processes of biodiversity change through time are possible using paleoenvironmental DNA, which is available much more readily than visible fossils and can provide information at a level of resolution that is not reached in classical palaeoecology.

Hydrogen production by Sulfurospirillum species enables syntrophic interactions of Epsilonproteobacteria

Hydrogen-producing bacteria are of environmental importance, since hydrogen is a major electron donor for prokaryotes in anoxic ecosystems. Epsilonproteobacteria are currently considered to be hydrogen-oxidizing bacteria exclusively. Here, we report hydrogen production upon pyruvate fermentation for free-living Epsilonproteobacteria, Sulfurospirillum spp. The amount of hydrogen produced is different in two subgroups of Sulfurospirillum spp., represented by S. cavolei and S. multivorans. The former produces more hydrogen and excretes acetate as sole organic acid, while the latter additionally produces lactate and succinate. Hydrogen production can be assigned by differential proteomics to a hydrogenase (similar to hydrogenase 4 from E. coli) that is more abundant during fermentation. A syntrophic interaction is established between Sulfurospirillum multivorans and Methanococcus voltae when cocultured with lactate as sole substrate, as the former cannot grow fermentatively on lactate alone and the latter relies on hydrogen for growth. This might hint to a yet unrecognized role of Epsilonproteobacteria as hydrogen producers in anoxic microbial communities.

Epsilonproteobacteria, such as Sulfurospirillum, can use molecular hydrogen as an electron donor for respiration. Here, the authors show that Sulfurospirillum can, in addition, release hydrogen during fermentation, allowing metabolic interactions with other hydrogen-consuming microorganisms.

Primary Malignant Lymphoma of the Salivary Glands

Five cases of primary malignant lymphomas of the salivary glands are reported. Four lymphomas arose in the parotid gland and one in the submandibular gland. All were non-Hodgkin lymphomas. In 4 cases the lymphomas were of low-grade malignancy, viz. 2 immunocytomas and 2 centroblastic/centrocytic malignant lymphomas, and 1 was a T-immunoblastic malignant lymphoma of high-grade malignancy. Four patients with localized disease were treated with radiotherapy and 1 patient with disseminated disease was treated with chemotherapy. One patient died from a disease unrelated to the malignant lymphoma, and 4 patients were alive at 66-136 months after treatment.

Dissimilar responses of larch stands in northern Siberia to increasing temperatures-a field and simulation based study

Arctic and alpine treelines worldwide differ in their reactions to climate change. A northward advance of or densification within the treeline ecotone will likely influence climate-vegetation feedback mechanisms. In our study, which was conducted in the Taimyr Depression in the North Siberian Lowlands, w present a combined field- and model-based approach helping us to better understand the population processes involved in the responses of the whole treeline ecotone, spanning from closed forest to single-tree tundra, to climate warming. Using information on stand structure, tree age, and seed quality and quantity from seven sites, we investigate effects of intra-specific competition and seed availability on the specific impact of recent climate warming on larch stands. Field data show that tree density is highest in the forest-tundra, and average tree size decreases from closed forest to single-tree tundra. Age-structure analyses indicate that the trees in the closed forest and forest-tundra have been present for at least ~240 yr. At all sites except the most southerly ones, past establishment is positively correlated with regional temperature increase. In the single-tree tundra, however, a change in growth form from krummholz to erect trees, beginning ~130 yr ago, rather than establishment date has been recorded. Seed mass decreases from south to north, while seed quantity increases. Simulations with LAVESI (Larix Vegetation Simulator) further suggest that relative density changes strongly in response to a warming signal in the forest-tundra while intra-specific competition limits densification in the closed forest and seed limitation hinders densification in the single-tree tundra. We find striking differences in strength and timing of responses to recent climate warming. While forest-tundra stands recently densified, recruitment is almost non-existent at the southern and northern end of the ecotone due to autecological processes. Palaeo-treelines may therefore be inappropriate to infer past temperature changes at a fine scale. Moreover, a lagged treeline response to past warming will, via feedback mechanisms, influence climate change in the future.

The NiFe Hydrogenases of the Tetrachloroethene-Respiring Epsilonproteobacterium Sulfurospirillum multivorans: Biochemical Studies and Transcription Analysis

The organohalide-respiring Epsilonproteobacterium Sulfurospirillum multivorans is able to grow with hydrogen as electron donor and with tetrachloroethene (PCE) as electron acceptor; PCE is reductively dechlorinated to cis-1,2-dichloroethene. Recently, a genomic survey revealed the presence of four gene clusters encoding NiFe hydrogenases in its genome, one of which is presumably periplasmic and membrane-bound (MBH), whereas the remaining three are cytoplasmic. To explore the role and regulation of the four hydrogenases, quantitative real-time PCR and biochemical studies were performed with S. multivorans cells grown under different growth conditions. The large subunit genes of the MBH and of a cytoplasmic group 4 hydrogenase, which is assumed to be membrane-associated, show high transcript levels under nearly all growth conditions tested, pointing toward a constitutive expression in S. multivorans. The gene transcripts encoding the large subunits of the other two hydrogenases were either not detected at all or only present at very low amounts. The presence of MBH under all growth conditions tested, even with oxygen as electron acceptor under microoxic conditions, indicates that MBH gene transcription is not regulated in contrast to other facultative hydrogen-oxidizing bacteria. The MBH showed quinone-reactivity and a characteristic UV/VIS spectrum implying a cytochrome b as membrane-integral subunit. Cell extracts of S. multivorans were subjected to native polyacrylamide gel electrophoresis (PAGE) and hydrogen oxidizing activity was tested by native staining. Only one band was detected at about 270 kDa in the particulate fraction of the extracts, indicating that there is only one hydrogen-oxidizing enzyme present in S. multivorans. An enrichment of this enzyme and SDS PAGE revealed a subunit composition corresponding to that of the MBH. From these findings we conclude that the MBH is the electron-donating enzyme system in the PCE respiratory chain. The roles for the other three hydrogenases remain unproven. The group 4 hydrogenase might be involved in hydrogen production upon fermentative growth.

The requirement of GnRH at the beginning of the five-day CO-Synch + controlled internal drug release protocol in beef heifers

The objective of this study was to determine if the omission of GnRH at controlled internal drug release device (CIDR) insertion would impact pregnancy rates to timed AI (TAI) in beef heifers enrolled in a 5-d CO-Synch + CIDR protocol that used 1 PGF2α dose given at CIDR removal. Yearling beef heifers in Ohio in 2 consecutive breeding seasons (2011, n = 151, and 2012, n = 143; Angus × Simmental), Utah (2012, n = 265; Angus × Hereford), Idaho (2012, n = 127; Charolais), and Wyoming (2012, n = 137; Angus) were enrolled in the 5-d CO-Synch + CIDR protocol. At CIDR insertion (d -5), heifers were randomly assigned either to receive 100 μg GnRH (GnRH+; n = 408) or not to receive GnRH (GnRH-; n = 415). At CIDR removal (d 0 of the experiment), 25 mg PGF2α was administered to all heifers. All heifers were inseminated by TAI and given 100 μg GnRH 72 h after PGF2α (d 3). In heifers at the Ohio locations (n = 294), presence of a corpus luteum (CL) at CIDR insertion (d -5) was determined via assessment of progesterone concentrations (2011) and ovarian ultrasonography (2012). Subsequently, in both years, ovarian ultrasound was conducted on d 0 to determine the presence of a new CL. In this same subgroup of heifers, blood samples for progesterone analysis were collected on d 3 to assess luteal regression. Pregnancy diagnosis was performed between 32 and 38 d after TAI. At CIDR withdrawal, presence of a new CL was greater (P < 0.05) in the GnRH+ (55.8%, 82/147) than GnRH- (26.5%, 39/147) treatment. Incidence of failed luteal regression did not differ between the GnRH+ (3.4%) and GnRH- (0.7%) treatments. Pregnancy rate to TAI did not differ between the GnRH+ (50.5%) and GnRH- (54.9%) treatments. In conclusion, although the incidence of a new CL at CIDR removal was increased in the GnRH+ treatment, omission of the initial GnRH treatment in the 5-d CO-Synch + CIDR protocol did not influence TAI pregnancy rate in yearling beef heifers. In addition, a single dose of PGF2α at CIDR removal was effective at inducing luteolysis in yearling beef heifers enrolled in the 5-d CO-Synch + CIDR protocol, regardless of whether or not the initial GnRH treatment was given.

71 EFFECTS OF A CONTROLLED DIETARY EXPOSITION TO ZERALENONE ON SELECTED REPRODUCTIVE PARAMETERS IN DAIRY COWS

Whole plant corn silage is an important component of dairy cow nutrition. Growing conditions in a moderate climate, as are present in large parts of Europe and North America, are often beneficial for mould contaminations to occur. Very commonly, varieties of Fusarium spp. grow on the corn plant producing the non-steroidal estrogenic mycotoxin zearalenone (ZEN). Numerous studies have shown that ZEN massively interacts with the porcine reproductive system. Nevertheless, only a few studies have assessed the possible effects on dairy cows, most publications being field studies following accidental exposure. Therefore, it was aim of the present study to assess the effects of a controlled dietary exposition on selected reproductive parameters in dairy cows. The chosen exposure concentration was within the range of the ‘Commision Recommendation on the presence of deoxynivalenol, zearalenone, ochratoxin A, T-2 and HT-2 and fumonisins in products intended for animal feeding’ of the European Union. Corn plants were artificially inoculated with Fusarium spp. and the silage obtained from the whole plant was analysed to determine to which degree the silage contained ZEN. Thirty Holstein Friesian cows and heifers (aged between 2 years 3 months and 5 years at calving) were allocated to 3 groups with 10 animals each: control (CTL), uncontaminated silage; ZEN 50, silage with 0.25 mg of ZEN/day; and ZEN 100, silage with 0.5 mg of ZEN/day. The contaminated rations were distributed by automated feeding stations to ensure an equal uptake. Feeding began 7 days post-parturition. Blood samples were obtained twice weekly for 12 weeks and were analyzed regarding the progesterone level via radioimmunoassay. At the same time, the oestrous cycle was monitored by ultrasonography. Furthermore, the size of the corpus luteum (CL) was measured 7 ± 2 days after the third ovulation. Simultaneously, the luteal blood flow was documented via Doppler ultrasonography. The peripheral blood progesterone level (xgeom. ± CV; CTL: 9.3 ± 1.7; ZEN 50: 8.5 ± 1.6; ZEN100: 7.1 ± 1.5) did not differ among groups. Furthermore, it was not possible to detect differences in luteal blood flow, size of the CL (mean ± SD; CTL: 6.4 ± 1.7 cm2; ZEN50: 5.9 ± 1.3 cm2; ZEN 100: 5.0 ± 1.0 cm2) or the ratio of luteal size and size of the area supplied with blood (CTL: 0.1 ± 0.1; ZEN 50: 0.1 ± 0.0; ZEN 100: 0.1 ± 0.1). Although the mean length of the oestrous cycles (n = 60; distributed among groups) did not differ among groups (CTL: 24.0 ± 1.7 days; ZEN 50: 27.2 ± 1.6 days; ZEN 100: 27.7 ± 1.4 days), it was possible to detect an interaction between the age of the animal and the treatment regarding the cycle length in tendency (P < 0.07) by two-way ANOVA. The results of the present study indicate that, independent of the age of the animal, exposure to ZEN even within recommended dosages might result in an endocrine disruption in dairy cows. A larger sample size would contribute to the verification of these findings. Further analyses regarding the peripheral level of 17β-estradiol as well as molecular examinations are under progress.

Predicting water table response to rainfall events, central Florida

A rise in water table in response to a rainfall event is a complex function of permeability, specific yield, antecedent soil-water conditions, water table level, evapotranspiration, vegetation, lateral groundwater flow, and rainfall volume and intensity. Predictions of water table response, however, commonly assume a linear relationship between response and rainfall based on cumulative analysis of water level and rainfall logs. By identifying individual rainfall events and responses, we examine how the response/rainfall ratio varies as a function of antecedent water table level (stage) and rainfall event size. For wells in wetlands and uplands in central Florida, incorporating stage and event size improves forecasting of water table rise by more than 30%, based on 10 years of data. At the 11 sites studied, the water table is generally least responsive to rainfall at smallest and largest rainfall event sizes and at lower stages. At most sites the minimum amount of rainfall required to induce a rise in water table is fairly uniform when the water table is within 50 to 100 cm of land surface. Below this depth, the minimum typically gradually increases with depth. These observations can be qualitatively explained by unsaturated zone flow processes. Overall, response/rainfall ratios are higher in wetlands and lower in uplands, presumably reflecting lower specific yields and greater lateral influx in wetland sites. Pronounced depth variations in rainfall/response ratios appear to correlate with soil layer boundaries, where corroborating data are available.

Temporal pattern of feeding and drinking behaviour of gestating sows

Abstract. The aim of the present study was to investigate the temporal pattern of feed and water intake behaviour of gestating sows housed in a dynamic group. The dataset included 90 sows (parity 1 to 7). Feed and water intake were recorded by electronic feeding and drinking stations. To describe the feed and water intake behaviour single visits were combined into meals and drinking bouts. A log survivorship function identified the characteristic interval length to differentiate between two bouts. Interval lengths larger than 12 min separated two meals (29 min two drinking bouts). The meal and drinking bout criteria were used to derive the following traits: feeding and drinking duration per day (FD, DD), interval duration within feeding (pauseF) or drinking (pauseW) meal, feeding and drinking meal duration per day (FMD, DMD) and feeding and drinking visits per day (FV, DV). Additionally, an eating rank was calculated according to the order of the sows at the feeding station. The results showed that nulliparous and primiparous sows had higher FD, pauseF, FMD and FV in contrast to biparous and multiparous sows (P<0.05). The DD of primiparous sows was significantly lower than that of older sows. The eating rank increased over time while nulliparous sows increased their rank more slowly than older sows. Low to moderate repeatabilities were found for feed intake traits (0.23 to 0.41); higher repeatabilities for drinking traits (0.45 to 0.55) and eating rank (0.71) indicating high variation between sows, which could be used for the identification of diseases.

A high-resolution anatomical atlas of the transcriptome in the mouse embryo

The manuscript describes the “digital transcriptome atlas” of the developing mouse embryo, a powerful resource to determine co-expression of genes, to identify cell populations and lineages and to identify functional associations between genes relevant to development and disease.

Ascertaining when and where genes are expressed is of crucial importance to understanding or predicting the physiological role of genes and proteins and how they interact to form the complex networks that underlie organ development and function. It is, therefore, crucial to determine on a genome-wide level, the spatio-temporal gene expression profiles at cellular resolution. This information is provided by colorimetric RNA in situ hybridization that can elucidate expression of genes in their native context and does so at cellular resolution. We generated what is to our knowledge the first genome-wide transcriptome atlas by RNA in situ hybridization of an entire mammalian organism, the developing mouse at embryonic day 14.5. This digital transcriptome atlas, the Eurexpress atlas (http://www.eurexpress.org), consists of a searchable database of annotated images that can be interactively viewed. We generated anatomy-based expression profiles for over 18,000 coding genes and over 400 microRNAs. We identified 1,002 tissue-specific genes that are a source of novel tissue-specific markers for 37 different anatomical structures. The quality and the resolution of the data revealed novel molecular domains for several developing structures, such as the telencephalon, a novel organization for the hypothalamus, and insight on the Wnt network involved in renal epithelial differentiation during kidney development. The digital transcriptome atlas is a powerful resource to determine co-expression of genes, to identify cell populations and lineages, and to identify functional associations between genes relevant to development and disease.

In situ hybridization (ISH) can be used to visualize gene expression in cells and tissues in their native context. High-throughput ISH using nonradioactive RNA probes allowed the Eurexpress consortium to generate a comprehensive, interactive, and freely accessible digital gene expression atlas, the Eurexpress transcriptome atlas (http://www.eurexpress.org), of the E14.5 mouse embryo. Expression data for over 15,000 genes were annotated for hundreds of anatomical structures, thus allowing us to systematically identify tissue-specific and tissue-overlapping gene networks. We illustrate the value of the Eurexpress atlas by finding novel regional subdivisions in the developing brain. We also use the transcriptome atlas to allocate specific components of the complex Wnt signaling pathway to kidney development, and we identify regionally expressed genes in liver that may be markers of hematopoietic stem cell differentiation.

Asthma and IL-4 receptor alpha gene variants

Linkage of allergy to chromosome 16 has been described in several studies, together with a positive association with interleukin 4 receptor alpha gene variants. Our aim was to replicate these findings in a sample of German and Swedish families recruited through sib-pairs affected by bronchial asthma. None of the markers showed linkage with the main phenotype of asthma or with total serum IgE. Seropositivity to D. pteronyssinus showed borderline significance in a region flanking the IL4Ralpha location. Single nucleotide polymorphisms (SNPs) leading to the protein exchanges I50V, E375A, C406R, S478P and Q551R in the IL-4 receptor alpha were examined for allele sharing in sibs with asthma. Multiple regression analysis was performed for association with total serum IgE and specific IgE. Allele sharing of IL4Ralpha SNPs in asthmatic children was not significantly increased for any of the examined SNPs except for the intracytoplasmatic polymorphism 551R (0.79 vs. 0.84 expected, P = 0.044). The variants 50V, 478P and 551R were associated with slightly increased, and 375A and 406R with decreased total IgE levels, all at a non-significant level. None of the examined IL4Ralpha variants were correlated to asthma severity. In summary, a single gene effect of IL4Ralpha variants or any other gene on chromosome 16 could not be shown in this selected population of children with asthma. As there could be interactions with multiple genetic and environmental factors, IL4Ralpha could still be involved in asthma pathogenesis.

Treatment of primary monosymptomatic nocturnal enuresis with desmopressin: predictive factors

OBJECTIVE

To investigate predictive factors for the outcome of treatment of primary monosymptomatic nocturnal enuresis (PMNE) with desmopressin.

PATIENTS AND METHODS

Data from a large open multicentre study were analysed. The study comprised 399 children with PMNE who were recruited for long-term desmopressin treatment. Before treatment a history was taken and the children observed for 4 weeks. After a 6-week dose-titration period with desmopressin, the children were classified into four groups depending on the response rate.

RESULTS

The children who improved during desmopressin treatment were older, had fewer wet nights during the observation period and had only one wet episode during the night, mostly after midnight. Many of them did not require the maximum dose of desmopressin to become dry. No hereditary factor for the response to desmopressin was found.

CONCLUSION

Those most likely to be permanently dry with desmopressin treatment are older children who respond to 20 microg desmopressin and who do not wet frequently.

[Can homeopathy be integrated in a university hospital?]

BACKGROUND AND OBJECTIVE

The Dr. von Hauner Children's Hospital Munich has conducted a pilot project for 4 years, aiming at the integration of homeopathic concomitant treatment into daily clinical practice. This study was carried out to clarify whether the project is successful and accepted by physicians, nurses, and parents.

METHODS

Questionnaires, all standardized and anonymous, were handed out to 137 physicians, 212 nurses and paramedics, and 1,048 parents of children treated at the hospital.

RESULTS

69% of the physicians appreciated concomitant homeopathic treatments, more than 60% believed the integration of homeopathy is suggestive, 75% saw a need for clinical research in homeopathy. 25% of the staff now had a more positive view towards homeopathy. 63% of the parents appreciated concomitant treatment, but only 19% are willing to participate in double-blind studies.

CONCLUSIONS

Integration of homeopathy in a university hospital is possible. Therapeutic work should be accompanied by scientific research.

A novel polymorphism in the 5' promoter region of the human interleukin-4 receptor alpha-chain gene is associated with decreased soluble interleukin-4 receptor protein levels

Interleukin (IL)-4 exerts its biological effects through binding to the IL-4 receptor (IL4R) complex, plays a central role in stimulating B-cell differentiation, and is crucial for the development of T helper 2 cells. Recently, a soluble form of the human IL4R alpha chain (sIL4R alpha), which is produced by alternate mRNA splicing of exon 8, was discovered. sIL4R is thought to play an important role in either enhancing or inhibiting IL-4 signalling. We analyzed the 5' promoter region of the human IL4R alpha-chain gene (IL4RA) of healthy volunteers by DNA sequencing and found three novel single-nucleotide polymorphisms (SNPs; T-890C, T-1914C, C-3223T) and one novel short tandem repeat [(CAAAA)(5-7)-3600]. The two common promoter region SNPs T-1914C and C-3223T as well as six known coding SNPs in the IL4RA gene were genotyped in healthy blood donors by PCR with sequence-specific primers; total sIL4R levels were measured by ELISA. Results revealed a highly significant association of the -3223T variant with lowered sIL4R levels (two-tailed t-test, P=0.0002). Results remained highly significant after Bonferroni adjustment for multiple comparisons (P=0.0017). Moreover, the C-3223T variant was found to be in strong linkage disequilibrium with the extracellular 150V variant (P<0.001), which was recently described to be associated with atopic asthma in a Japanese population. Since this novel IL4RA promoter region SNP is common (allele frequency 29.8%), we conclude that it may be of importance for the genetic regulation of the IL-4 signalling pathway.

Elucidation of the role of functional amino acid residues of the small sialidase from Clostridium perfringens by site-directed mutagenesis

Bacterial sialidases represent important colonization or virulence factors. The development of a rational basis for the design of antimicrobials targeted to sialidases requires the knowledge of the exact roles of their conserved amino acids. A recombinant enzyme of the 'small' (43 kDa) sialidase of Clostridium perfringens was used as a model in our study. Several conserved amino acids, identified by alignment of known sialidase sequences, were altered by site-directed mutagenesis. All recombinant enzymes were affinity-purified and the enzymatic characteristics were determined. Among the mutated enzymes with modifications in the environment of the 4-hydroxyl group of bound sialic acids, D54N and D54E exhibited minor changes in substrate binding. However, a reduced activity and changes in their pH curves indicate the importance of a charged group at this area. R56K, which is supposed to bind directly to sialic acids as in the homologous Salmonella typhimurium sialidase, showed a 2500-fold reduced activity. The amino acids Asp-62 and Asp-100 are probably involved in catalysis, indicated by reduced activities and altered temperature and pH curves of mutant enzymes. Exchanging Glu-230 with threonine or aspartic acid led to dramatic decreases in activity. This residue and Y347 are supposed to be crucial for providing a suitable environment for catalysis. However, unaltered pH curves of mutant sialidases exclude their direct involvement in protonation or deprotonation events. These results indicate that the interactions with the substrates vary in different sialidases and that they might be more complex than suggested by mere static X-ray structures.

Visualization of a cytoskeleton-like FtsZ network in chloroplasts

It has been a long-standing dogma in life sciences that only eukaryotic organisms possess a cytoskeleton. Recently, this belief was questioned by the finding that the bacterial cell division protein FtsZ resembles tubulin in sequence and structure and, thus, may be the progenitor of this major eukaryotic cytoskeletal element. Here, we report two nuclear-encoded plant ftsZ genes which are highly conserved in coding sequence and intron structure. Both their encoded proteins are imported into plastids and there, like in bacteria, they act on the division process in a dose-dependent manner. Whereas in bacteria FtsZ only transiently polymerizes to a ring-like structure, in chloroplasts we identified persistent, highly organized filamentous scaffolds that are most likely involved in the maintenance of plastid integrity and in plastid division. As these networks resemble the eukaryotic cytoskeleton in form and function, we suggest the term "plastoskeleton" for this newly described subcellular structure.

Studies on linkage and association of atopy with the chromosomal region 12q13-24

BACKGROUND

Several studies have shown linkage of bronchial asthma, allergic rhinitis and total serum IgE concentration to the chromosomal region 12q13-24 in ethnical diverse populations. This region harbours a number of candidate genes for asthma and atopy, including stem cell factor (SCF), leukotriene A4 hydrolase (LTA4H), thyroid receptor 2 (TR2), and signal transducer and activator of transcription 6 (STAT6). However, the same region was shown as well to be linked to other diseases with inflammatory character. So far no variants in any of these genes have been published which would allow association studies and confirm the pathogenicity of any of these genes.

OBJECTIVE

We wanted to test for linkage of the chromosomal region 12q13-24 with the atopic phenotype without regard to clinical manifestations. Furthermore we screened for common nucleotide polymorphisms in candidate genes to enable association studies.

METHODS

We employed sib-pair linkage analysis and transmission disequilibrium testing with regard to four highly polymorphic microsatellite markers in 12q13-24 in atopic nuclear families. In addition, we looked for polymorphisms in the genes coding for SCF, LTA4H, TR2 and STAT6 performing SSCP-analysis and direct genomic sequencing.

RESULTS

We found no evidence for linkage of the genomic region 12q13-24 to elevated total serum IgE levels, specific sensitization to common inhalant allergens or atopy. Furthermore we identified three nucleotide polymorphisms including one common variant in the gene coding for SCF. No association of this polymorphism and any of the atopic phenotypes was seen.

CONCLUSION

We conclude from our data that genes in the chromosomal region 12q13-24 and in particular SCF are unlikely to exert a major effect on the induction of the atopic phenotype in our Caucasian population. However, we did not focus on the asthmatic and thereby inflammatory aspect of atopy which might explain these results in contradiction to previous studies.

Economic analysis of a phase III study of G-CSF vs placebo following allogeneic blood stem cell transplantation

Hematopoietic colony-stimulating factors (CSF) decrease the duration of neutropenia following stem cell transplantation (SCT). With CSF-mobilized allogeneic blood SCT (alloBSCT), the yields of CD34+ cells are several-fold higher than in other SCT settings, raising concern that post-transplant CSF use may be unnecessary. In this study, we estimate the resource and cost implications associated with CSF use following alloBSCT. A cost identification analysis was conducted for 44 patients on a randomized, double-blind placebo-controlled trial of G-CSF following alloBSCT. Study drug was given daily until an absolute neutrophil count (ANC) > or = 1000 cells/microl. Billing information from the time of transplant to day +100 was analyzed. The median number of days to an ANC > or = 500 cells/microl was shorter in the G-CSF arm, 10.5 days vs 15 days (P < 0.001), while platelet recovery and rates of acute graft-versus-host disease (GVHD) and survival were similar. Resource use was similar, including days hospitalized, days on antibiotics, blood products transfused and outpatient visits. Total median post-transplant costs were $76577 for G-CSF patients and $78799 for placebo patients (P = 0.93). G-CSF following allogeneic blood SCT decreased the median duration of absolute neutropenia and did not incur additional costs, but did not result in shorter hospitalizations, or less frequent antibiotic use.

A randomized, double-blind trial of filgrastim (granulocyte colony-stimulating factor) versus placebo following allogeneic blood stem cell transplantation

Blood stem cell transplantation (BSCT) results in rapid hematopoietic recovery in both the allogeneic and autologous transplant settings. Because of the large numbers of progenitor cells in mobilized blood, the administration of growth factors after transplantation may not provide further acceleration of hematopoietic recovery. A randomized, double-blind, placebo-controlled study was performed to determine the effects of filgrastim (granulocyte colony-stimulating factor; G-CSF) administration on hematopoietic recovery after allogeneic BSCT. Fifty-four patients with hematologic malignancies undergoing a related, HLA-matched allogeneic BSCT were randomly assigned to receive daily filgrastim at 10 microg/kg or placebo starting on the day of transplantation. A minimum of 3 x 10(6) CD34(+) cells/kg in the allograft was required for transplantation. All patients received a standard preparative regimen and a standard regimen for the prevention of graft-versus-host disease (GVHD). The median time to achieve an absolute neutrophil count greater than 0.5 x 10(9)/L was 11 days (range, 9-20 days) for patients who received filgrastim compared with 15 days (range, 10-22 days) for patients who received placebo (P =.0082). The median time to achieve a platelet count greater than 20 x 10(9)/L was 13 days (range, 8-35 days) for patients who received filgrastim compared with 15.5 days (range, 8-42 days) for patients who received placebo (P =.79). There were no significant differences for red blood cell transfusion independence, the incidence of acute GVHD, or 100-day mortality between the groups. The administration of filgrastim appears to be a safe and effective supportive-care measure following allogeneic BSCT.