Effects of recultivation on soil organic carbon sequestration in abandoned coal mining sites: a meta-analysis

Opencast coal mining results in high loss of soil organic carbon (SOC), which may be restored via recultivation. Common strategies include liming, topsoil application, and phytoremediation. It remains unclear, however, which parameters determine the effectiveness of these varying recultivation strategies especially regarding SOC sequestration. This meta-analysis analyses the effect of varying recultivation strategies on SOC sequestration under different climate and soil conditions (pH, texture, depth) as well as in relation to time, based on 404 data entries from 51 studies. All included climatic regions recorded increases in SOC stocks, with tropical soils showing the highest potential for relative gains at up to 637%. We demonstrate that loamy soils sequester twice as much newly introduced SOC than sand. Strategy-wise, the highest mean rate of SOC sequestration is achieved by forest after topsoil application (3.9 Mg ha^-1 a^-1), agriculture after topsoil application (2.3 Mg ha^-1 a^-1), and agriculture with topsoil and fertiliser application (1.9 Mg ha^-1 a^-1) with a response ratio of 304%, 281%, and 218%, respectively. Soils analysed to less then 40 cm depth show higher SOC sequestration rates (< 10 cm: 0.6 Mg ha^-1 a^-1, < 20 cm: 1.0 Mg ha^-1 a^-1, and 20-40 cm: 0.4 Mg ha^-1 a^-1; response ratio of 123%, 68%, and 73%, respectively) than those analysed to a depth of 41-80 cm (0.1 Mg ha^-1 a^-1; response ratio of 6%). In terms of pH, strongly acidic soils (pH < 4.5) and alkaline conditions (pH > 7) offer the most beneficial environment for SOC sequestration at 0.4 Mg ha^-1 a^-1 and 0.8 Mg ha^-1 a^-1, respectively (185% and 273% response). Given comparable SOC sequestration potentials of forest after topsoil application, agriculture without amendments, and forest without amendments, we recommend to weigh these strategies against each other. Potentially decisive aspects are short- vs. long-term economic gains, food security concerns, and-in case of agriculture-the risk of overintensification leading to losses in SOC. Our data suggests that amendments exert considerable influence on SOC sequestration and need to be introduced under careful consideration.

Nitrogen fixing bacteria facilitate microbial biodegradation of a bio-based and biodegradable plastic in soils under ambient and future climatic conditions

We discovered a biological mechanism supporting microbial degradation of bio-based poly(butylene succinate-co-adipate) (PBSA) plastic in soils under ambient and future climates. Here, we show that nitrogen-fixing bacteria facilitate the microbial degradation of PBSA by enhancing fungal abundance, accelerating plastic-degrading enzyme activities, and shaping/interacting with plastic-degrading fungal communities.

The impact of social complexity on the visual exploration of others' actions in preschoolers with autism spectrum disorder

BACKGROUND

Typical development of socio-communicative skills relies on keen observation of others. It thus follows that decreased social attention negatively impacts the subsequent development of socio-communicative abilities in children with autism spectrum disorders (ASD). In addition, studies indicate that social attention is modulated by context and that greater social difficulties are observed in more socially demanding situations. Our study aims to investigate the effect of social complexity on visual exploration of others' actions in preschoolers.

METHODS

To investigate the impact of social complexity, we used an eye-tracking paradigm with 26 typically developing preschoolers (TD, age = 3.60 ± 1.55) and 37 preschoolers with ASD (age = 3.55 ± 1.21). Participants were shown videos of two children engaging in socially simple play (parallel) versus socially complex play (interactive). We subsequently quantified the time spent and fixation duration on faces, objects, bodies, as well as the background and the number of spontaneous gaze shifts between socially relevant areas of interest.

RESULTS

In the ASD group, we observed decreased time spent on faces. Social complexity (interactive play) elicited changes in visual exploration patterns in both groups. From the parallel to the interactive condition, we observed a shift towards socially relevant parts of the scene, a decrease in fixation duration, as well as an increase in spontaneous gaze shifts between faces and objects though there were fewer in the ASD group.

LIMITATIONS

Our results need to be interpreted cautiously due to relatively small sample sizes and may be relevant to male preschoolers, given our male-only sample and reported phenotypic differences between males and females.

CONCLUSION

Our results suggest that similar to TD children, though to a lesser extent, visual exploration patterns in ASD are modulated by context. Children with ASD that were less sensitive to context modulation showed decreased socio-communicative skills or higher levels of symptoms. Our findings support using naturalistic designs to capture socio-communicative deficits in ASD.

Meta-analysis on how manure application changes soil organic carbon storage

Manure application to agricultural soils is widely considered as a source of nutrients and a method of maintaining levels of soil organic carbon (SOC) to mitigate climate change. At present, it is still unclear which factors are responsible for the SOC stock dynamics. Therefore, we analyzed the relationship between SOC stock changes and site characteristics, soil properties, experiment characteristics and manure characteristics. Overall, we included 101 studies with a total of 592 treatments. On average, the application of manure on agricultural soils increased SOC stocks by 35.4%, corresponding to 10.7 Mg ha^-1. Manure applications in conventional tillage systems led to higher SOC stocks (+ 2.2 Mg ha^-1) than applications under reduced tillage. Soil organic carbon increase upon manure application was higher in soils under non-tropical climate conditions (+ 2.7 Mg ha^-1) compared to soils under sub-tropical climate. Larger SOC increases after manure application were achieved in intermediate and shallow topsoils (in 0-15 cm by 9.5 Mg ha^-1 and in 16-20 cm by 13.6 Mg ha^-1), but SOC stocks were also increased in deeper soils (> 20 cm 4.6 Mg ha^-1), regardless of the tillage intensity. The highest relative SOC increase (+ 48%) was achieved if the initial SOC was below 1% but the absolute SOC increased with increasing initial SOC. Clay soils showed higher SOC increase rates compared to sandy soils (+ 3.1 Mg ha^-1). Acidic soils showed comparable relative effects but a higher stock difference than neutral (+ 5.1 Mg ha^-1) and alkaline soils (+ 5.1 Mg ha^-1). The application of farmyard-, cattle- and pig manure showed the highest SOC increases (50%, 32% and 41%, respectively), while green manure and straw showed only minor effects. If manure applications were combined with additional mineral fertilizer, the SOC increases were higher (+ 1.7 Mg ha^-1) compared to manure alone. Higher applied amounts generally led to higher SOC stocks. However the annually applied amount is only important under conventional tillage, non-tropical climate conditions, and pH-neutral as well as SOC-rich or SOC-depleted soils and if no additional mineral fertilization is applied. Further studies should focus on the SOC dynamics under tropical climate conditions and factors influencing a potential carbon saturation. In both cases, the number of data was too small. For this reason, additional field studies should be conducted primarily in the tropics. On the other hand, long-term field trials should be re-assessed or newly established to specifically investigate potential saturation effects and long-term (> 20 years) fertilizer effects and carbon sequestration.

The potential of δ2Hn-alkanes and δ18Osugar for paleoclimate reconstruction - A regional calibration study for South Africa

The hydrogen isotopic composition of leaf wax-derived n-alkanes (δ²H_n-alkanes) is a widely applied proxy for (paleo)climatic changes. It has been suggested that the coupling with the oxygen isotopic composition of hemicellulose-derived sugars (δ¹⁸O_sugar) - an approach dubbed 'paleohygrometer' - might allow more robust and quantitative (paleo)hydrological reconstructions. However, the paleohygrometer remains to be evaluated and tested regionally. In this study, topsoil samples from South Africa, covering extensive environmental gradients, are analysed. δ²H_n-alkanes correlates significantly with the isotopic composition of precipitation (δ²H_p), whereas no significant correlation exists between δ¹⁸O_sugar and δ¹⁸O_p. The apparent fractionation (ε_app) is the difference between δ²H_n-alkanes and δ²H_p (ε_{app 2H}) and δ¹⁸O_sugar and δ¹⁸O_p (ε_{app 18O}), respectively, and integrates i) isotopic enrichment due to soil water evaporation, ii) leaf (and xylem) water transpiration and iii) biosynthetic fractionation. We find no correlation of ε_{app 18O} nor for ε_{app 2H} with temperature, and no correlation of ε_{app 2H} with potential evapotranspiration and an aridity index. By contrast, ε_{app 18O} correlates significantly with both potential evapotranspiration and the aridity index. This highlights the strong effect of evapotranspirative enrichment on δ¹⁸O_sugar. In study areas without plant predominance using Crassulacean Acid Metabolism (CAM), coupling δ¹⁸O_sugar and δ²H_n-alkanes enables to reconstruct δ²H_p and δ¹⁸O_p with an offset of Δδ²H = 6 ± 27‰ and Δδ¹⁸O = 0.8 ± 3.7‰, respectively, as well as relative humidity (RH) with an offset of ΔRH = 6 ± 17%. The paleohygrometer does, however, not work well for our study areas where CAM plants prevail (reconstructed δ¹⁸O_p, δ²H_p and RH are off by 3.1‰, 27.2‰ and 31.7%). This probably reflects plant-specific (phenological) adaptations and/or post-photosynthetic exchange reactions related to CAM metabolism. Overall, our findings corroborate that δ²H_n-alkanes and δ¹⁸O_sugar are valuable proxies, and the paleohygrometer is a promising approach for paleoclimate reconstructions in southern Africa.

Spatial and temporal 2H and 18O isotope variation of contemporary precipitation in the Bale Mountains, Ethiopia. Isotopes Environ Health Stud 2020;56:122-135. [PMID: 32008378 DOI: 10.1080/10256016.2020.1717487]

East Africa is an underrepresented region in respect of monitoring the stable isotopic composition of precipitation (δ¹⁸O_prec and δ²H_prec). In 2017, we collected precipitation samples from ten weather stations located along an altitudinal transect ranging from 1304 to 4375 m a.s.l. The δ¹⁸O_prec and δ²H_prec values varied from -8.7 to +3.7 ‰ and -38 to +29 ‰, respectively. The local meteoric water line is characterised by a lower slope, a higher intercept and more positive d-excess values (δ²H = 5.3 ± 0.2 * δ¹⁸O + 14.9 ± 0.9) compared to the global meteoric water line. Both altitude and amount of precipitation clearly correlate with our isotope data. However, the δ¹⁸O_prec and δ²H_prec values show at the same time a seasonal pattern reflecting rainy versus dry season. More enriched isotope values prevailed shortly after the end of the dry season; more depleted isotope values coincided with high precipitation amounts recorded in May, August and September. Moreover, HYSPLIT trajectories reveal that during the dry season water vapour originates primarily from the Arabian Sea, whereas during the wet season it originates primarily from the Southern Indian Ocean. These findings challenge the traditional amount effect interpretation of paleoclimate isotope records from East Africa and rather point to a previously underestimated source effect.

Middle Stone Age foragers resided in high elevations of the glaciated Bale Mountains, Ethiopia

Studies of early human settlement in alpine environments provide insights into human physiological, genetic, and cultural adaptation potentials. Although Late and even Middle Pleistocene human presence has been recently documented on the Tibetan Plateau, little is known regarding the nature and context of early persistent human settlement in high elevations. Here, we report the earliest evidence of a prehistoric high-altitude residential site. Located in Africa's largest alpine ecosystem, the repeated occupation of Fincha Habera rock shelter is dated to 47 to 31 thousand years ago. The available resources in cold and glaciated environments included the exploitation of an endemic rodent as a key food source, and this played a pivotal role in facilitating the occupation of this site by Late Pleistocene hunter-gatherers.

Performance of Mapping Approaches for Whole-Genome Bisulfite Sequencing Data in Crop Plants

DNA methylation is involved in many different biological processes in the development and well-being of crop plants such as transposon activation, heterosis, environment-dependent transcriptome plasticity, aging, and many diseases. Whole-genome bisulfite sequencing is an excellent technology for detecting and quantifying DNA methylation patterns in a wide variety of species, but optimized data analysis pipelines exist only for a small number of species and are missing for many important crop plants. This is especially important as most existing benchmark studies have been performed on mammals with hardly any repetitive elements and without CHG and CHH methylation. Pipelines for the analysis of whole-genome bisulfite sequencing data usually consists of four steps: read trimming, read mapping, quantification of methylation levels, and prediction of differentially methylated regions (DMRs). Here we focus on read mapping, which is challenging because un-methylated cytosines are transformed to uracil during bisulfite treatment and to thymine during the subsequent polymerase chain reaction, and read mappers must be capable of dealing with this cytosine/thymine polymorphism. Several read mappers have been developed over the last years, with different strengths and weaknesses, but their performances have not been critically evaluated. Here, we compare eight read mappers: Bismark, BismarkBwt2, BSMAP, BS-Seeker2, Bwameth, GEM3, Segemehl, and GSNAP to assess the impact of the read-mapping results on the prediction of DMRs. We used simulated data generated from the genomes of Arabidopsis thaliana, Brassica napus, Glycine max, Solanum tuberosum, and Zea mays, monitored the effects of the bisulfite conversion rate, the sequencing error rate, the maximum number of allowed mismatches, as well as the genome structure and size, and calculated precision, number of uniquely mapped reads, distribution of the mapped reads, run time, and memory consumption as features for benchmarking the eight read mappers mentioned above. Furthermore, we validated our findings using real-world data of Glycine max and showed the influence of the mapping step on DMR calling in WGBS pipelines. We found that the conversion rate had only a minor impact on the mapping quality and the number of uniquely mapped reads, whereas the error rate and the maximum number of allowed mismatches had a strong impact and leads to differences of the performance of the eight read mappers. In conclusion, we recommend BSMAP which needs the shortest run time and yields the highest precision, and Bismark which requires the smallest amount of memory and yields precision and high numbers of uniquely mapped reads.

Circulating breast-derived DNA allows universal detection and monitoring of localized breast cancer

BACKGROUND

Tumor-derived circulating cell-free DNA (cfDNA) is present in the plasma of individuals with cancer. Assays aimed at detecting common cancer mutations in cfDNA are being developed for the detection of several cancer types. In breast cancer, however, such assays have failed to detect the disease at a sensitivity relevant for clinical use, in part due to the absence of multiple common mutations that can be co-detected in plasma. Unlike individual mutations that exist only in a subset of tumors, unique DNA methylation patterns are universally present in cells of a common type and therefore may be ideal biomarkers. Here we describe the detection and quantification of breast-derived cfDNA using a breast-specific DNA methylation signature.

PATIENTS AND METHODS

We collected plasma from patients with localized breast cancer before and throughout treatment with neoadjuvant chemotherapy and surgery (N = 235 samples).

RESULTS

Pretreatment breast cfDNA was detected in patients with localized disease with a sensitivity of 80% at 97% specificity. High breast cfDNA levels were associated with aggressive molecular tumor profiles and metabolic activity of the disease. During neoadjuvant chemotherapy, breast cfDNA levels decreased dramatically. Importantly, the presence of breast cfDNA towards the end of the chemotherapy regimen reflected the existence of residual disease.

CONCLUSION

We propose that breast-specific cfDNA is a universal and powerful marker for the detection and monitoring of breast cancer.

Substitution of mineral fertilizers with biogas digestate plus biochar increases physically stabilized soil carbon but not crop biomass in a field trial

Various organic amendments are scrutinized as potential agricultural management strategies to ensure soil productivity while mitigating climate change due to the accumulation of soil organic matter (OM). The objectives of this experiment were to study the effects of biochar and biogas digestate versus mineral fertilizer on crop aboveground biomass as well as fractions and mineralization of soil organic carbon (SOC). Samples of a sandy Cambisol were taken 14 months after establishment of a field experiment in Germany. Treatments included application of equal nitrogen in the form of mineral fertilizer or liquid biogas digestate without biochar (B₀), with 1 Mg biochar ha^-1season^-1 for two growing seasons (B₂), or with 40 Mg biochar ha^-1 application (B₄₀). Soil fractionation in water separated water-extractable and free particulate (fPOM) OM, followed by sonification and sieving to isolate occluded particulate (oPOM) and < 20 μm aggregate-occluded and mineral-associated OM. CO₂ emissions were measured during 92-day laboratory incubations at 10 and 20 °C. Analysis of variance found digestate lowered (p < 0.05) rye aboveground biomass compared to mineral fertilizer (9.3 vs. 10.6 Mg ha^-1), while biochar had no effect. B₄₀ treatments increased C mineralization during incubation by 16% and contained 3.8 times more SOC than B₀ treatments. This additional SOC was allocated to fPOM (52%), oPOM (22%), and the <20 μm fraction (26%). Digestate application increased SOC content of oPOM by 11% compared to mineral fertilizer. Furthermore, combined application of 40 Mg biochar ha^-1 with digestate resulted in 20% more SOC in the <20 μm fraction than biochar with mineral fertilizer. The lack of a significant fertilizer or biochar-fertilizer interaction effect on C mineralization during incubation demonstrates the stability of SOC from digestate alone or in combination with biochar. The absence of significant differences in SOC content between B₀ and B₂ treatments demonstrates the difficulty of documenting SOC sequestration in the field at low biochar application rates.

Sauna, sweat and science II - do we sweat what we drink?

Inspired by a previous 'Sauna, sweat and science' study [Zech et al. Isot Environ Health Stud. 2015;51(3):439-447] and out of curiosity and enthusiasm for stable isotope and sauna research we aimed at answering the question 'do we sweat (isotopically) what we drink'? We, therefore, pulse-labelled five test persons in a sauna experiment with beverages that were ²H-enriched at about +25,600 ‰. Sweat samples were collected during six sauna rounds and the hydrogen isotope composition δ²H_sweat was determined using an isotope ratio mass spectrometer. Before pulse labelling, δ²H_sweat - reflecting by approximation body water - ranged from -32 to -22 ‰. This is ∼35 ‰ enriched compared to usual mid-European drinking water and can be explained with hydrogen-bearing food as well as with the respiratory loss of ²H-depleted vapour. The absence of a clearly detectable ²H pulse in sweat after pulse labelling and δ²H_sweat results of ≤+250 ‰ due to a fast ²H equilibration with body water are moreover a clearly negative answer to our research question also in a short-term consideration. Given that the recovery of the tracer based on an isotope mass balance calculation is clearly below 100 %, we finally answer the question 'where did the rest of the tracer go?'

Long-term fire resilience of the Ericaceous Belt, Bale Mountains, Ethiopia

Fire is the most frequent disturbance in the Ericaceous Belt (ca 3000-4300 m.a.s.l.), one of the most important plant communities of tropical African mountains. Through resprouting after fire, Erica establishes a positive fire feedback under certain burning regimes. However, present-day human activity in the Bale Mountains of Ethiopia includes fire and grazing systems that may have a negative impact on the resilience of the ericaceous ecosystem. Current knowledge of Erica-fire relationships is based on studies of modern vegetation, lacking a longer time perspective that can shed light on baseline conditions for the fire feedback. We hypothesize that fire has influenced Erica communities in the Bale Mountains at millennial time-scales. To test this, we (1) identify the fire history of the Bale Mountains through a pollen and charcoal record from Garba Guracha, a lake at 3950 m.a.s.l., and (2) describe the long-term bidirectional feedback between wildfire and Erica, which may control the ecosystem's resilience. Our results support fire occurrence in the area since ca 14 000 years ago, with particularly intense burning during the early Holocene, 10.8-6.0 cal ka BP. We show that a positive feedback between Erica abundance and fire occurrence was in operation throughout the Lateglacial and Holocene, and interpret the Ericaceous Belt of the Ethiopian mountains as a long-term fire resilient ecosystem. We propose that controlled burning should be an integral part of landscape management in the Bale Mountains National Park.

Phenolic Compounds as Unambiguous Chemical Markers for the Identification of Keystone Plant Species in the Bale Mountains, Ethiopia

: Despite the fact that the vegetation pattern and history of the Bale Mountains in Ethiopia were reconstructed using pollen, little is known about the former extent of Erica species. The main objective of the present study is to identify unambiguous chemical proxies from plant-derived phenolic compounds to characterize Erica and other keystone species. Mild alkaline CuO oxidation has been used to extract sixteen phenolic compounds. After removal of undesired impurities, individual phenols were separated by gas chromatography and were detected by mass spectrometry. While conventional phenol ratios such as syringyl vs. vanillyl and cinnamyl vs. vanillyl and hierarchical cluster analysis of phenols failed for unambiguous Erica identification, the relative abundance of coumaryl phenols (>0.20) and benzoic acids (0.05-0.12) can be used as a proxy to distinguish Erica from other plant species. Moreover, a Random Forest decision tree based on syringyl phenols, benzoic acids (>0.06), coumaryl phenols (<0.21), hydroxybenzoic acids, and vanillyl phenols (>0.3) could be established for unambiguous Erica identification. In conclusion, serious caution should be given before interpreting this calibration study in paleovegetation reconstruction in respect of degradation and underground inputs of soil organic matter.

Biochar effects on phosphorus availability in agricultural soils: A meta-analysis

Phosphorus (P) is a limiting nutrient for plants and an essential element for all life on Earth. As the resources of phosphate rock are depleting, new management tools for environmentally friendly P fertilizers are needed. In order to achieve this, recent studies have proposed to use biochar, a carbon-rich solid product of thermochemical conversion of biomass with minimal or zero oxygen supply, as slow-release P fertilizer. However, the effects of biochar on plant-available P in soils have been reported to be variable. Therefore, we quantitatively evaluated existing peer-reviewed data using meta-analysis to draw general conclusions. In the present study, we evaluated 108 pairwise comparisons to their response of biochar application on P availability in soils. Our results indicate that biochar can act as a short-, mid-, and long-term P fertilizer with its effect depending on feedstock, pyrolysis temperature and application amount. Overall, the addition of biochar significantly increased the P availability in agricultural soil by a factor of 4.6 (95% confidence interval 3.4–5.9), independent of the used feedstock for biochar production. Only biochar application amounts above 10 Mg ha⁻¹ and biochar produced at temperatures lower than 600 °C significantly increased the P availability of agricultural soils. The application of biochar to acid (pH < 6.5) and neutral soils (pH 6.5–7.5) significantly increased plant-P availability by a factor of 5.1 and 2.4, respectively (95% confidence interval 3.5–6.7 and 1.4–3.4, respectively), while there was no significant effect in alkaline soils (pH > 7.5). Taken together, this meta-analysis shows that biochar significantly enhances plant-available P in biochar-amended soils at least for five years.

Dynamics of labile and stable carbon and priming effects during composting of sludge and lop mixtures amended with low and high amounts of biochar

This study was performed to investigate the effects of biochar amendment on the dynamics of labile and stable carbon (C) fractions and associated priming effects during composting of sludge and lop mixtures. Furthermore, the effect of aerobic composting on biochar stable C composition was analyzed. Low amounts of activated carbon [dosage 0-1.7% w/w] and higher amounts of charcoal [dosage 0-38% w/w] were applied to the organic feedstock mixture in two separated full-scale composting trials under practical field conditions. The results demonstrated that biochar-C was substantially more stable during the composting process than compost-derived organic C resulting in a significant enrichment of the stable black C fraction in the final product. Furthermore, stability of final products were significantly increased, if more biochar has been initially added prior to composting. However, labile organic C losses were increased (positive priming) if low amounts of activated carbon have been applied, while no short-term priming effects could be observed after adding charcoal over a wider application range. Moreover, biochar stable C composition was positively affected during the composting process. Based on our results, a biochar amendment ≥10% (w/w) seems generally favorable for an accelerated composting process, while stability characteristics of the final products were improved. However, some caution seems to be required concerning the usability of activated carbon due to positive priming.

Short-term carbon dynamics in a temperate grassland and heathland ecosystem exposed to 104 days of drought followed by irrigation

Temperate ecosystems are susceptible to drought events. The effect of a severe drought (104 days) followed by irrigation on the plant C uptake, its assimilation and input of C in soil were examined using a triple ¹³CO₂ pulse-chase labelling experiment in model grassland and heathland ecosystems. First ¹³CO₂ pulse at day 0 of the experiment revealed much higher ¹³C tracer uptake for shoots, roots and soil compared to the second pulse (day 44), where all plants showed significantly lower ¹³C tracer uptake. After the third ¹³CO₂ pulse (day 70), very low ¹³C uptake in shoots led to a negligible allocation of ¹³C into roots and soil. During irrigation after the severe drought, the ¹³C tracer that was allocated in plant tissues during the second and third pulse labelling was re-allocated in roots and soil, as soon as the irrigation started. This re-allocation was higher and longer lasting in heathland compared to grassland ecosystems.

Does differential visual exploration contribute to visual memory impairments in 22q11.2 microdeletion syndrome?

BACKGROUND

Chromosome 22q11.2 microdeletion syndrome (22q11.2DS) is a genetic syndrome characterised by a unique cognitive profile. Individuals with the syndrome present several non-verbal deficits, including visual memory impairments and atypical exploration of visual information. In this study, we seek to understand how visual attention may contribute to memory difficulties in 22q11.2DS by tracking eye movements during the encoding phase of a visual short-term memory task.

METHOD

Eye movements were recorded during a computerised version of the multiple-choice Benton Visual Retention Test, which consisted of exploring and then recognising complex visual stimuli. Seventy-four participants affected by 22q11.2DS were compared with 70 typically developing participants.

RESULTS

Participants with 22q11.2DS performed less well than healthy controls on the task and spent more time and fixations on the principal (larger central) figures and less time and fixations on the smaller peripheral figures within the stimuli.

CONCLUSIONS

This study is the first to investigate visual attention in 22q11.2DS during a memory task. The results delineate impaired processes during encoding that affect visual memory performance. The findings may be especially useful for informing interventions intended to boost visual learning in patients with 22q11.2DS.

Understanding others: a pilot investigation of cognitive and affective facets of social cognition in patients with 22q11.2 deletion syndrome (22q11DS)

BACKGROUND

Although significant impairments in the affective and cognitive facets of social cognition have been highlighted in patients with 22q11.2 deletion syndrome (22q11DS) in previous studies, these domains have never been investigated simultaneously within the same group of participants. Furthermore, despite theoretical evidence, associations between these two processes and schizotypal symptoms or social difficulties in this population have been scarcely examined.

METHODS

Twenty-nine participants with 22q11DS and 27 typically developing controls (N = 5 siblings; N = 22 unrelated controls) aged between 11 and 21 years participated in the study. Both groups were matched for age and gender distribution. Two computerized social cognition tasks evaluating perspective and emotion recognition abilities were administered to all participants. The levels of schizotypal trait expression and social functioning were further investigated in both groups, based on a validated self-report questionnaire (Schizotypal Personality Questionnaire) and parental interview (Vineland Adaptive Behavior Scales).

RESULTS

Participants with 22q11DS exhibited lower perspective-taking and emotion recognition capacities than typically developing controls. The two socio-cognitive dimensions investigated here were further correlated in healthy controls. The efficiency of perspective-taking processes (response time) was marginally related to the degree of schizotypal trait expression in patients with 22q11DS.

CONCLUSIONS

This study first provides support for significant deficits in two core facets of social cognition in 22q11DS. The associations observed between the experimental tasks and measures of social functioning or schizotypal symptoms in 22q11DS open promising research avenue, which should be more deeply investigated in future studies.

Effects of ageing and senescence on pancreatic β-cell function

Ageing is generally associated with deterioration of organ function and regenerative potential. In the case of pancreatic β-cells, an age-related decline in proliferative potential is well documented, and was proposed to contribute to the increased prevalence of type 2 diabetes in the elderly. The effects of ageing on β-cell function, namely glucose-stimulated insulin secretion (GSIS), have not been studied as extensively. Recent work revealed that, surprisingly, β-cells of mature mice and humans secrete more insulin than young β-cells in response to high glucose concentrations, potentially serving to counteract age-related peripheral insulin resistance. This functional change appears to be orchestrated by p16(Ink4A) -driven cellular senescence and downstream remodelling of chromatin structure and DNA methylation, enhancing the expression of genes controlling β-cell function. We propose that activation of the cellular senescence program drives life-long functional maturation of β-cells, due to β-cell hypertrophy, enhanced glucose uptake and more efficient mitochondrial metabolism, in parallel to locking these cells in a non-replicative state. We speculate that the beneficial aspects of this process can be harnessed to enhance GSIS. Other age-related mechanisms, which are currently poorly understood, act to increase basal insulin secretion levels also in low glucose conditions. This leads to an overall reduction in the amplitude of insulin secretion between low and high glucose at old age, which may contribute to a deterioration in metabolic control.

Visual processing of emotional dynamic faces in 22q11.2 deletion syndrome

INTRODUCTION

The 22q11.2 deletion syndrome (22q11DS) is a neurogenetic syndrome. Individuals affected by this syndrome present poor social functioning and a high risk for the development of psychiatric disorders. Accurate emotion recognition and visual exploration of faces represent important skills for appropriate development of social cognition in individuals with 22q11DS. For these reasons, there is elevated interest in establishing relevant ways to test the mechanisms associated with emotion recognition in patients with 22q11DS.

METHODS

This study investigated emotional recognition and visual exploration of emotional faces in persons with 22q11DS, with a dynamic emotion task using an eye-tracking device. To our knowledge, no previous studies have used emotional dynamic stimuli with 22q11DS, despite improved ecological validity of dynamic stimuli compared with static images. Furthermore, these stimuli provide the opportunity to collect reaction times, as indicators of the emotional intensity necessary for identifying each emotion.

RESULTS

In our task, we observed comparable accuracy in emotion recognition in the 22q11DS and healthy control groups. However, individuals with 22q11DS were slower to recognise the emotions. They also spent less time looking at the nose during happy and fearful faces.

CONCLUSIONS

These results suggest that individuals with 22q11DS may need either more time or more pronounced emotional cues to correctly label facial expressions.

Toward the Standardization of Biochar Analysis: The COST Action TD1107 Interlaboratory Comparison

Biochar produced by pyrolysis of organic residues is increasingly used for soil amendment and many other applications. However, analytical methods for its physical and chemical characterization are yet far from being specifically adapted, optimized, and standardized. Therefore, COST Action TD1107 conducted an interlaboratory comparison in which 22 laboratories from 12 countries analyzed three different types of biochar for 38 physical-chemical parameters (macro- and microelements, heavy metals, polycyclic aromatic hydrocarbons, pH, electrical conductivity, and specific surface area) with their preferential methods. The data were evaluated in detail using professional interlaboratory testing software. Whereas intralaboratory repeatability was generally good or at least acceptable, interlaboratory reproducibility was mostly not (20% < mean reproducibility standard deviation < 460%). This paper contributes to better comparability of biochar data published already and provides recommendations to improve and harmonize specific methods for biochar analysis in the future.

Allocation of freshly assimilated carbon into primary and secondary metabolites after in situ ¹³C pulse labelling of Norway spruce (Picea abies)

Plants allocate carbon (C) to sink tissues depending on phenological, physiological or environmental factors. We still have little knowledge on C partitioning into various cellular compounds and metabolic pathways at various ecophysiological stages. We used compound-specific stable isotope analysis to investigate C partitioning of freshly assimilated C into tree compartments (needles, branches and stem) as well as into needle water-soluble organic C (WSOC), non-hydrolysable structural organic C (stOC) and individual chemical compound classes (amino acids, hemicellulose sugars, fatty acids and alkanes) of Norway spruce (Picea abies) following in situ (13)C pulse labelling 15 days after bud break. The (13)C allocation within the above-ground tree biomass demonstrated needles as a major C sink, accounting for 86% of the freshly assimilated C 6 h after labelling. In needles, the highest allocation occurred not only into the WSOC pool (44.1% of recovered needle (13)C) but also into stOC (33.9%). Needle growth, however, also caused high (13)C allocation into pathways not involved in the formation of structural compounds: (i) pathways in secondary metabolism, (ii) C-1 metabolism and (iii) amino acid synthesis from photorespiration. These pathways could be identified by a high (13)C enrichment of their key amino acids. In addition, (13)C was strongly allocated into the n-alkyl lipid fraction (0.3% of recovered (13)C), whereby (13)C allocation into cellular and cuticular exceeded that of epicuticular fatty acids. (13)C allocation decreased along the lipid transformation and translocation pathways: the allocation was highest for precursor fatty acids, lower for elongated fatty acids and lowest for the decarbonylated n-alkanes. The combination of (13)C pulse labelling with compound-specific (13)C analysis of key metabolites enabled tracing relevant C allocation pathways under field conditions. Besides the primary metabolism synthesizing structural cell compounds, a complex network of pathways consumed the assimilated (13)C and kept most of the assimilated C in the growing needles.

Sauna, sweat and science - quantifying the proportion of condensation water versus sweat using a stable water isotope ((2)H/(1)H and (18)O/(16)O) tracer experiment

Most visitors of a sauna appreciate the heat pulse that is perceived when water is poured on the stones of a sauna stove. However, probably only few bathers are aware that this pleasant heat pulse is caused by latent heat being released onto our skin due to condensation of water vapour. In order to quantify the proportion of condensation water versus sweat to dripping water of test persons we conducted sauna experiments using isotopically labelled (δ(18)O and δ(2)H) thrown water as tracer. This allows differentiating between 'pure sweat' and 'condensation water'. Two ways of isotope mass balance calculations were applied and yielded similar results for both water isotopes. Accordingly, condensation contributed considerably to dripping water with mean proportions of 52 ± 12 and 54 ± 7% in a sauna experiment in winter semester 2011/12 and 30 ± 13 and 33 ± 6% in a sauna experiment in winter semester 2012/13, respectively, depending on the way of calculating the isotope mass balance. It can be concluded from the results of our dual isotope labelling sauna experiment that it is not all about sweat in the sauna.

Acceleration of Biochar Surface Oxidation during Composting?

Biochar composting experiments were performed to determine whether composting is a suitable method to accelerate biochar surface oxidation for increasing its reactivity. To assess the results, surface properties of Terra Preta (Brazil) and ancient charcoal pit (Northern Italy) biochars were additionally investigated. Calculation of O/C ratios by energy-dispersive X-ray spectroscopy demonstrated the anticipated increasing values from fresh biochars (0.13) to composted biochars (0.40), and finally charcoal pit biochars (0.54) and ancient Terra Preta biochars (0.64). By means of Fourier transformation infrared microscopy, formation of carboxylic and phenolic groups on biochars surface could be detected. Carboxylic acids of three composted biochars increased up to 14%, whereas one composted biochar showed a 21% lower proportion of carboxylic acids compared to the corresponding fresh biochar. Phenolic groups increased by 23% for the last mentioned biochar, and on all other biochars phenolic groups decreased up to 22%. Results showed that biochar surface oxidation can be accelerated through composting but still far away from ancient biochars.

Release of nitrous oxide and dinitrogen from a transition bog under drained and rewetted conditions due to denitrification: results from a [15N]nitrate-bromide double-tracer study

Denitrification is well known being the most important nitrate-consuming process in water-logged peat soils, whereby the intermediate compound nitrous oxide (N(2)O) and the end product dinitrogen (N(2)) are ultimately released. The present study was aimed at evaluating the release of these gases (due to denitrification) from a nutrient-poor transition bog ecosystem under drained and three differently rewetted conditions at the field scale using a (15)N-tracer approach ([(15)N]nitrate application, 30 kg N ha(-1)) and a common closed-chamber technique. The drained site is characterized by a constant water table (WT) of -30 cm (here referred to as D30), while rewetted sites represent a constant WT of -15 cm, a constant WT of 0 cm (i.e. waterlogged), and an initial WT of 0 cm (which decreased slightly during the experiment), respectively, (here referred to as R15, R0, and R0(d), respectively). The highest N(2)O emissions were observed at D30 (291 µg N(2)O-N m(-2) h(-1)) as well as at R0d (665 µg N(2)O-N m(-2) h(-1)). At the rewetted peat sites with a constant WT (i.e. R15 and R0), considerably lower N2O emissions were observed (maximal 37 µg N(2)O-N m(-2) h(-1)). Concerning N(2) only at the initially water-logged peat site R0d considerable release rates (up to 3110 µg N(2)-N m(-2) h(-1)) were observed, while under drained conditions (D30) no N(2) emission and under rewetted conditions with a constant WT (R15 and R0) significantly lower N(2) release rates (maximal 668 µg N(2)-N m(-2) h(-1)) could be detected. In addition, it has been found that natural WT fluctuations at rewetted peat sites, in particular a rapid drop down of the WT, can induce high emission rates for both N(2)O and N(2).

Mechanisms of water interaction with pore systems of hydrochar and pyrochar from poplar forestry waste

The aim of this study was to understand the water-surface interactions of two chars obtained by gasification (pyrochar) and hydrothermal carbonization (hydrochar) of a poplar biomass. The two samples revealed different chemical compositions as evidenced by solid state (13)C NMR spectroscopy. In fact, hydrochar resulted in a lignin-like material still containing oxygenated functionalities. Pyrochar was a polyaromatic system in which no heteronuclei were detected. After saturation with water, hydrochar and pyrochar were analyzed by fast field cycling (FFC) NMR relaxometry. Results showed that water movement in hydrochar was mainly confined in very small pores. Conversely, water movement in pyrochar led to the conclusion that a larger number of transitional and very large pores were present. These results were confirmed by porosity evaluation derived from gas adsorption. Variable-temperature FFC NMR experiments confirmed a slow-motion regime due to a preferential diffusion of water on the solid surface. Conversely, the higher number of large pores in pyrochar allowed slow movement only up to 50 °C. As the temperature was raised to 80 °C, water interactions with the pore surface became weaker, thereby allowing a three-dimensional water exchange with the bulk liquid. This paper has shown that pore size distribution was more important than chemical composition in affecting water movement in two chemically different charred systems.

Improved δ(13)C analysis of amino sugars in soil by ion chromatography-oxidation-isotope ratio mass spectrometry

RATIONALE

Amino sugars build up microbial cell walls and are important components of soil organic matter. To evaluate their sources and turnover, δ(13)C analysis of soil-derived amino sugars by liquid chromatography was recently suggested. However, amino sugar δ(13)C determination remains challenging due to (1) a strong matrix effect, (2) CO2 -binding by alkaline eluents, and (3) strongly different chromatographic behavior and concentrations of basic and acidic amino sugars. To overcome these difficulties we established an ion chromatography-oxidation-isotope ratio mass spectrometry method to improve and facilitate soil amino sugar analysis.

METHODS

After acid hydrolysis of soil samples, the extract was purified from salts and other components impeding chromatographic resolution. The amino sugar concentrations and δ(13)C values were determined by coupling an ion chromatograph to an isotope ratio mass spectrometer. The accuracy and precision of quantification and δ(13)C determination were assessed.

RESULTS

Internal standards enabled correction for losses during analysis, with a relative standard deviation <6%. The higher magnitude peaks of basic than of acidic amino sugars required an amount-dependent correction of δ(13)C values. This correction improved the accuracy of the determination of δ(13)C values to <1.5‰ and the precision to <0.5‰ for basic and acidic amino sugars in a single run.

CONCLUSIONS

This method enables parallel quantification and δ(13)C determination of basic and acidic amino sugars in a single chromatogram due to the advantages of coupling an ion chromatograph to the isotope ratio mass spectrometer. Small adjustments of sample amount and injection volume are necessary to optimize precision and accuracy for individual soils.

Genotoxic and phytotoxic risk assessment of fresh and treated hydrochar from hydrothermal carbonization compared to biochar from pyrolysis

Biochar is discussed as an option for climate change mitigation via C sequestration and may promote sustainable resource efficiency. Large-scale field trials and commercial business with char materials have already started. Therefore char materials have to be assessed for toxic compounds. We tested genotoxic effects of different hydrochars and biochars with the Tradescantia micronucleus test. For this purpose chromosomal aberrations in pollen cells of Tradescantia in the form of micronuclei were evaluated microscopically after defined exposition to extracts from char materials. Hydrochars from hydrothermal carbonization mostly exhibited significantly negative results. Additional germination experiments with hydrochar showed total germination inhibition at additions above five percent v/v in comparison to biochar. However, biological post-treatment of previously toxic hydrochar was successful and toxic effects were eliminated completely. Some post-treated hydrochars even showed growth stimulating effects. Our results clearly demonstrate the necessity of risk assessment with bioindicators. The chosen tests procedures can contribute to biochar and hydrochar characterization for safe application.

A novel methodological approach for δ(18)O analysis of sugars using gas chromatography-pyrolysis-isotope ratio mass spectrometry

Although the instrumental coupling of gas chromatography-pyrolysis-isotope ratio mass spectrometry (GC-Py-IRMS) for compound-specific δ(18)O analysis has been commercially available for more than a decade, this method has been hardly applied so far. Here we present the first GC-Py-IRMS δ(18)O results for trimethylsilyl-derivatives of plant sap-relevant sugars and a polyalcohol (glucose, fructose, sucrose, raffinose and pinitol). Particularly, we focus on sucrose, which is assimilated in leaves and which is the most important transport sugar in plants and hence of utmost relevance in plant physiology and paleoclimate studies. Replication measurements of sucrose standards and concentration series indicate that the GC-Py-IRMS δ(18)O measurements are not stable over time and that they are amount (area) dependent. We, therefore, suggest running sample batch replication measurements in alternation with standard concentration series of reference material. This allows for carrying out (i) a drift correction, (ii) a calibration against reference material and (iii) an amount (area) correction. Tests with (18)O-enriched water do not provide any evidence for oxygen isotope exchange reactions affecting sucrose and raffinose. We present the first application of GC-Py-IRMS δ(18)O analysis for sucrose from needle extract (soluble carbohydrate) samples. The obtained δ(18)Osucrose/ Vienna Standard Mean Ocean Water (VSMOW) values are more positive and vary in a wider range (32.1-40.1 ‰) than the δ(18)Obulk/ VSMOW values (24.6-27.2 ‰). Furthermore, they are shown to depend on the climate parameters maximum day temperature, relative air humidity and cloud cover. These findings suggest that δ(18)Osucrose of the investigated needles very sensitively reflects the climatically controlled evaporative (18)O enrichment of leaf water and thus highlights the great potential of GC-Py-IRMS δ(18)Osucrose analysis for plant physiology and paleoclimate studies.

Albedo impact on the suitability of biochar systems to mitigate global warming

Biochar application to agricultural soils can change the surface albedo which could counteract the climate mitigation benefit of biochar systems. However, the size of this impact has not yet been quantified. Based on empirical albedo measurements and literature data of arable soils mixed with biochar, a model for annual vegetation cover development based on satellite data and an assessment of the annual development of surface humidity, an average mean annual albedo reduction of 0.05 has been calculated for applying 30-32 Mg ha(-1) biochar on a test field near Bayreuth, Germany. The impact of biochar production and application on the carbon cycle and on the soil albedo was integrated into the greenhouse gas (GHG) balance of a modeled pyrolysis based biochar system via the computation of global warming potential (GWP) characterization factors. The analysis resulted in a reduction of the overall climate mitigation benefit of biochar systems by 13-22% due to the albedo change as compared to an analysis which disregards the albedo effect. Comparing the use of the same quantity of biomass in a biochar system to a bioenergy district heating system which replaces natural gas combustion, bioenergy heating systems achieve 99-119% of the climate benefit of biochar systems according to the model calculation.

Glucose metabolism: key endogenous regulator of β-cell replication and survival

Recent studies in mice have shown that pancreatic β-cells have a significant potential for regeneration, suggesting that regenerative therapy for diabetes is feasible. Genetic lineage tracing studies indicate that β-cell regeneration is based on the replication of fully differentiated, insulin-positive β-cells. Thus, a major challenge for this field is to identify and enhance the molecular pathways that control β-cell replication and mass. We review evidence, from human genetics and mouse models, that glucose is a major signal for β-cell replication. The mitogenic effect of blood glucose is transmitted via glucose metabolism within β-cells, and through a signalling cascade that resembles the pathway for glucose-stimulated insulin secretion. We introduce the concept that the individual β-cell workload, defined as the amount of insulin that an individual β-cell must secrete to maintain euglycaemia, is the primary determinant of replication, survival and mass. We also propose that a cell-autonomous pathway, similar to that regulating replication, appears to be responsible for at least some of the toxic effects of glucose on β-cells. Understanding and uncoupling the mitogenic and toxic effects of glucose metabolism on β-cells may allow for the development of effective regenerative therapies for diabetes.

One step forward toward characterization: some important material properties to distinguish biochars

Terra Preta research gave evidence for the positive influence of charred organic material (biochar) on infertile tropical soils. Facing global challenges such as land degradation, fossil energy decline, water shortage, and climate change, the use of biochar as a soil amendment embedded into regional matter cycles seems to provide an all-round solution. However, little is known about biochar effects on individual ecosystem processes. Besides, the term is used for a variety of charred products. Therefore, the aim of this study was to investigate principal material properties of different chars to establish a minimum set of analytical properties and thresholds for biochar identification. For this purpose, chars from different production processes (traditional charcoal stack, rotary kiln, Pyreg reactor, wood gasifier, and hydrothermal carbonization) were analyzed for physical and chemical properties such as surface area, black carbon, polycyclic aromatic hydrocarbons, and elemental composition. Our results showed a significant influence of production processes on biochar properties. Based on our results, to identify biochar suitable for soil amendment and carbon sequestration, we recommend using variables with the following thresholds: O/C ratio <0.4, H/C ratio <0.6, black carbon >15% C, polyaromatic hydrocarbons lower than soil background values, and a surface area >100 m g.

Technical, economical, and climate-related aspects of biochar production technologies: a literature review

For the development of commercial biochar projects, reliable data on biochar production technologies is needed. For this purpose, peer-reviewed scientific articles on carbonization technologies (pyrolysis, gasification, hydrothermal carbonization, and flash carbonization) have been analyzed. Valuable information is provided by papers on pyrolysis processes, less information is available on gasification processes, and few papers about hydrothermal and flash carbonization technologies were identified. A wide range of data on the costs of char production (between 51 US$ per tonne pyrolysis biochar from yard waste and 386 US$ per tonne retort charcoal) and on the GHG balance of biochar systems (between -1054 kg CO(2)e and +123 kg CO(2)e per t dry biomass feedstock) have been published. More data from pilot projects are needed to improve the evaluation of biochar production technologies. Additional research on the influence of biochar application on surface albedo, atmospheric soot concentration, and yield responses is necessary to assess the entire climate impact of biochar systems. Above all, further field trials on the ability of different technologies to produce chars for agricultural soils and carbon sequestration are essential for future technology evaluation.

Age- and puberty-dependent association between IQ score in early childhood and depressive symptoms in adolescence

BACKGROUND

Lower cognitive functioning in early childhood has been proposed as a risk factor for depression in later life but its association with depressive symptoms during adolescence has rarely been investigated. Our study examines the relationship between total intelligence quotient (IQ) score at age 8 years, and depressive symptoms at 11, 13, 14 and 17 years.

METHOD

Study participants were 5250 children and adolescents from the Avon Longitudinal Study of Parents and their Children (ALSPAC), UK, for whom longitudinal data on depressive symptoms were available. IQ was assessed with the Wechsler Intelligence Scale for Children III, and self-reported depressive symptoms were measured with the Short Mood and Feelings Questionnaire (SMFQ).

RESULTS

Multi-level analysis on continuous SMFQ scores showed that IQ at age 8 years was inversely associated with depressive symptoms at age 11 years, but the association changed direction by age 13 and 14 years (age-IQ interaction, p<0.0001; age squared-IQ interaction, p<0.0001) when a higher IQ score was associated with a higher risk of depressive symptoms. This change in IQ effect was also found in relation to pubertal stage (pubertal stage-IQ interaction, 0.00049<p=0.038). At age 17 years, however, sex-specific differences emerged (sex-age squared-IQ interaction, p=0.0075). Whilst the risk effect of higher childhood IQ scores for depressive symptoms declined in females, and some analyses even supported an inverse association by age 17 years, it persisted in males.

CONCLUSIONS

Our results suggest that the association between cognitive ability in childhood and depressive symptoms in adolescence varies according to age and/or pubertal stage.

[Time processing in the velo-cardio-facial syndrome (22q11) and its link with the caudate nucleus]

INTRODUCTION

Velocardiofacial syndrome (VCFS) is a neurogenetic disorder caused by a microdeletion on chromosome 22q11. Among other cognitive impairments and learning difficulties, affected individuals show difficulties in estimating time intervals (Debbané et al., 2005). Interestingly, neuroimaging studies have found an increased volume of the basal ganglia of people with VCFS (Eliez et al., 2002; Kates et al., 2004; Campbell et al., 2006). Given that the caudate nucleus represents a central component of the cerebral network underlying temporal perception skills, the present report proposes to examine potential relationships between cerebral alteration to the caudate nucleus and time estimation in individuals with VCFS.

METHODS

A group of 30 patients with VCFS and 38 age-matched healthy individuals participated in time perception and time reproduction tasks. In the time perception task, individuals listened to two sequential stimuli and had to choose the longer of both stimuli by pressing a button. In the time reproduction task, subjects listened to a succession of sounds and once this succession had stopped they had to reproduce the same rhythm with their dominant index. Cerebral MRI images were also obtained for each participant. A manual tracing procedure was performed to measure the basal ganglia volume.

RESULTS

Participants with VCFS demonstrated significantly poorer performances during the time perception and time reproduction tasks in comparison to the control participants. Further, increased volume of the caudate nucleus was found in individuals with VCFS. Correlational analyses revealed a significant relationship between the caudate nucleus's volume and the performances obtained in the time perception task for control participants. This correlation was not found for individuals with VCFS.

CONCLUSION

The present results suggest that cerebral alterations to the caudate nucleus in VCFS may alter the temporal perception function it sustains.

Perinatal folate-related exposures and risk of psychotic symptoms in the ALSPAC birth cohort

BACKGROUND

It is unclear to what extent non-clinical psychotic experiences during childhood and adolescence share underlying aetiological mechanisms with schizophrenia. One candidate mechanism for schizophrenia involves the epigenetic status of the developing fetus, which depends on the internal folate-status of mother and child. Our study examines the relationships between multiple determinants of perinatal folate-status and development of psychotic experiences in adolescence.

METHODS

Study participants were up to 5344 mother-child pairs from the Avon Longitudinal Study of Parents and their Children, UK, with information on maternal and/or child MTHFR C677T genotype, maternal folate intake (supplementation at 18/32- weeks gestation; dietary intake at 32- weeks gestation) and psychosis-like symptoms (PLIKS) for children assessed at age 12.

RESULTS

Nominal evidence was observed that maternal folate supplementation at 18 weeks increased the odds of PLIKS in children (odds ratio(OR)=1.34; 95%-CI:[1.00;1.76]) and, consistent with this, that children of MTHFR C667T TT homozygous mothers had decreased odds of PLIKS (OR=0.72; 95%CI:[0.50;1.02]; recessive model) with strongest effects in boys (OR=0.44, 95%-CI:[0.22;0.79]; sex-specific p=0.029). None of the reported effects remained significant when corrected for multiple testing.

CONCLUSIONS

Overall, this study found no support that maternal/child MTHFR C677T genotype and maternal folate intake during pregnancy contribute to common aetiological pathways that are shared between schizophrenia and non-clinical psychotic symptoms in adolescents, assuming that decreased folate-status increases schizophrenia risk.

Compound-specific delta18O analyses of neutral sugars in soils using gas chromatography-pyrolysis-isotope ratio mass spectrometry: problems, possible solutions and a first application

Although gas chromatography-pyrolysis-isotope ratio mass spectrometry (GC-Py-IRMS) has allowed us to make online compound-specific delta18O measurements for about the last ten years, this technique has hardly been applied. We tested different pyrolysis reactor designs using standards (vanillin, ethylvanillin, a fatty acid methyl ester and alkanes) in order to optimize the GC-Py-IRMS delta18O measurements. The method was then applied to methylboronic acid (MBA) sugar derivatives (pentoses, 6-deoxyhexoses and hexoses). Plant- and microbial-derived monosaccharides were extracted hydrolytically from litter and topsoils before derivatization. The measured delta18O values of samples and co-analyzed reference material were first drift-corrected by use of regularly discharged pulses of CO reference gas. Secondly, they were corrected for the amount dependence of the delta18O values. Thirdly, the delta18O values were calibrated using the reference material (principle of 'Identical Treatment'), and, finally, a correction was applied by taking the hydrolytically introduced and water-exchangeable oxygen atoms into account. Our results suggest that the delta18O values of plant-derived monosaccharides in litter reflect the climatic conditions of the last year, whereas delta18O values of the respective topsoils reflect the averaged climate signal of the last decades or even centuries. This demonstrates the high potential of the method for palaeoclimate reconstructions.

Advantages of compound-specific stable isotope measurements over bulk measurements in studies on plant uptake of intact amino acids

Increasing interest in the ability of plants to take up amino acids has given rise to questions on the accuracy of the commonly used bulk method to measure and calculate amino acid uptake. This method uses bulk measurements of 13C and 15N enrichment in plant tissues after application of dual-labelled amino acids but some authors have recommended the use of compound-specific stable isotope (CSI) analysis of the plants' amino acids instead. However, there has never been a direct evaluation of both methods. We conducted a field study applying dual-labelled (13C, 15N) amino acids (glycine, valine, tyrosine and lysine) to soil of a Plantago lanceolata monoculture. Root and shoot samples were collected 24 h after label application and the isotope composition of the plant tissues was investigated using bulk and CSI measurements. Enrichment of 13C in the case of CSI measurements was limited to the applied amino acids, showing that no additional 13C had been incorporated into the plants' amino acid pool via the uptake of tracer-derived C-fragments. Compared with this rather conservative indicator of amino acid uptake, the 13C enrichment of bulk measurements was 8, 5, 1.6 and 6 times higher for fine roots, storage roots, shoot and the whole plant, respectively. These findings show that the additional uptake of tracer-derived C-fragments will result in a considerable overestimation of amino acid uptake in the case of bulk measurements. We therefore highly recommend the use of CSI measurements for future amino acid uptake studies due to their higher accuracy.

Impact of polymorphisms in WFS1 on prediabetic phenotypes in a population-based sample of middle-aged people with normal and abnormal glucose regulation

AIM/HYPOTHESIS

Recently, variants in WFS1 have been shown to be associated with type 2 diabetes. We aimed to examine metabolic risk phenotypes of WFS1 variants in glucose-tolerant people and in individuals with abnormal glucose regulation.

METHODS

The type 2 diabetes-associated WFS1 variant rs734312 (His611Arg) was studied in the population-based Inter99 cohort involving 4,568 glucose-tolerant individuals and 1,471 individuals with treatment-naive abnormal glucose regulation, and in an additional 3,733 treated type 2 diabetes patients.

RESULTS

The WFS1 rs734312 showed a borderline significant association with type 2 diabetes with directions and relative risks consistent with previous reports. In individuals with abnormal glucose regulation, the diabetogenic risk A allele of rs734312 was associated in an allele-dependent manner with a decrease in insulinogenic index (p = 0.025) and decreased 30-min serum insulin levels (p = 0.047) after an oral glucose load. In glucose-tolerant individuals the same allele was associated with increased fasting serum insulin concentration (p = 0.019) and homeostasis model assessment of insulin resistance (HOMA-IR; p = 0.026). To study the complex interaction of WFS1 rs734312 on insulin release and insulin resistance we introduced Hotelling's T (2) test. Assuming bivariate normal distribution, we constructed standard error ellipses of the insulinogenic index and HOMA-IR when stratified according to glucose tolerance status around the means of each WFS1 rs734312 genotype level. The interaction term between individuals with normal glucose tolerance and abnormal glucose regulation on the insulinogenic index and HOMA-IR was significantly associated with the traits (p = 0.0017).

CONCLUSIONS/INTERPRETATION

Type 2 diabetes-associated risk alleles of WFS1 are associated with estimates of a decreased pancreatic beta cell function among middle-aged individuals with abnormal glucose regulation.

Source monitoring for actions in adolescents with 22q11.2 deletion syndrome (22q11DS)

BACKGROUND

Source monitoring consists in identifying the origin of mental events. Recent research suggests that confusions over internally generated mental events may represent a cognitive marker for increased proneness to psychotic symptoms and disorders. We have examined source monitoring for actions in adolescents with the 22q11.2 deletion syndrome (22q11DS), a neurogenetic disease associated with high rates of schizophrenia during adulthood, and expected to observe source monitoring deficits in comparison to IQ-matched and typically developing controls.

METHOD

Eighteen adolescents with 22q11DS, 17 adolescents matched for age and IQ, and also 17 adolescents matched for age participated in this study. Our adapted action monitoring paradigm asked subjects to visualize a series of actions in three different conditions: (1) visualize themselves performing the action; (2) visualize the experimenter performing the action; or (3) simply repeat the action statements without visualization of the action performer.

RESULTS

The adolescents with 22q11DS performed adequately in terms of recognition (hits), but in comparison to both control groups, they committed more source confusions on correctly recognized items. Further examination revealed that the adolescents were more likely to demonstrate confusions between exterior sources in which the self was not involved.

CONCLUSIONS

Source monitoring deficits can be observed in adolescents with 22q11DS, a syndrome putting them at high risk for developing schizophrenia. These deficits are discussed in terms of early cognitive processes associated with genetic risk for schizophrenia.

Isotopic evidence for condensed aromatics from non-pyrogenic sources in soils--implications for current methods for quantifying soil black carbon

Black carbon (BC) is a complex continuum of partly charred organic matter predominantly consisting of condensed aromatic and graphitic moieties and it has high potential for long-term carbon sequestration in soils and sediments. There has been common agreement that BC is exclusively formed by incomplete combustion of organic matter, while non-pyrogenic sources are negligible. In this study, we investigated the stable carbon isotope signature of benzenepolycarboxylic acids (BPCAs) as molecular markers for BC to test if there is also a significant contribution of non-pyrogenic carbon to this fraction in soils. BPCAs were formed by hot nitric acid oxidation of different soils and analyzed by three different procedures: (i) elemental analysis - isotope ratio mass spectrometry (EA-IRMS) of bulk BPCAs and gas chromatography - combustion - isotope ratio mass spectrometry (GC-C-IRMS) of (ii) BPCA trimethylsilyl (TMS) derivatives, and (iii) BPCA methyl derivatives. Best accuracy and precision of isotope measurements were obtained by EA-IRMS of bulk BPCAs although this method has a risk of contamination by non-BC-derived compounds. The accuracy and precision of GC-C-IRMS measurements were superior for methyl derivatives (+/-0.1 per thousand and 0.5 per thousand, respectively) to those for TMS derivatives (+3.5 per thousand and 2.2 per thousand, respectively). Comparison of BPCA delta(13)C values of soil samples prior to and after laboratory and field incubations with both positive and negative (13)C labels at natural and artificial abundances revealed that up to 25% of the isolated BC fraction in soils had been produced in situ, without fire or charring. Commonly applied methods to quantify BC exclusively formed by pyrogenic processes may thus be biased by a significant non-pyrogenic fraction. Further research is encouraged to better define isolated BC fractions and/or understand mechanisms for non-pyrogenic BC production in soils.

Effects of a functional COMT polymorphism on brain anatomy and cognitive function in adults with velo-cardio-facial syndrome

BACKGROUND

Velo-cardio-facial syndrome (VCFS) is associated with deletions at chromosome 22q11, abnormalities in brain anatomy and function, and schizophrenia-like psychosis. Thus it is assumed that one or more genes within the deleted region are crucial to brain development. However, relatively little is known about how genetic variation at 22q11 affects brain structure and function. One gene on 22q11 is catechol-O-methyltransferase (COMT): an enzyme that degrades dopamine and contains a functional polymorphism (Val158Met) affecting enzyme activity. Here, we investigated the effect of COMT Val158Met polymorphism on brain anatomy and cognition in adults with VCFS.

METHOD

The COMT Val158Met polymorphism was genotyped for 26 adults with VCFS on whom DNA was available. We explored its effects on regional brain volumes using hand tracing approaches; on regional grey- and white-matter density using computerized voxel-based analyses; and measures of attention, IQ, memory, executive and visuospatial function using a comprehensive neuropsychological test battery.

RESULTS

After corrections for multiple comparisons Val-hemizygous subjects, compared with Met-hemizygotes, had a significantly larger volume of frontal lobes. Also, Val-hemizygotes had significantly increased grey matter density in cerebellum, brainstem, and parahippocampal gyrus, and decreased white matter density in the cerebellum. No significant effects of COMT genotype on neurocognitive performance were found.

CONCLUSIONS

COMT genotype effects on brain anatomy in VCFS are not limited to frontal regions but also involve other structures previously implicated in VCFS. This suggests variation in COMT activity is implicated in brain development in VCFS.

Improved compound-specific delta13C analysis of n-alkanes for application in palaeoenvironmental studies

We present an optimized method for compound-specific stable carbon isotope (delta(13)C) analysis of n-alkanes. For sample preparation, the traditionally used Soxhlet extraction was replaced by accelerated solvent extraction (ASE). delta(13)C values of individual n-alkanes--measured using gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS)--were first drift-corrected with regularly discharged pure CO(2) pulses as reference gas and, secondly, corrected for the amount dependence of the delta(13)C values by co-analyzing standards with varying analyte concentrations. Finally, the delta(13)C values were calibrated against two internal standards. The improved method was applied to selected sediment samples from a palaeoenvironmental study in subtropical NE Argentina. The measured delta(13)C values of all long-chain n-alkanes (nC(27), nC(29), nC(31) and nC(33)), representing biomarkers for terrestrial plants, correlate significantly with the delta(13)C of bulk organic matter (delta(13)C(TOC)). The latter is hence corroborated as a proxy for C3-C4 vegetation changes. Furthermore, the delta(13)C variations reveal higher amplitudes for nC(31) and nC(33) than for nC(27) and nC(29), indicating that the former n-alkanes mainly derive from C3 and/or C4 grasses, whereas the latter homologues mainly derive from C3 plants (trees and shrubs). Except for the lowermost part of the sediment core, the delta(13)C values of the mid-chain alkanes nC(23) and nC(25) do not reflect the terrestrial delta(13)C pattern, thus indicating that they are probably mainly of lacustrine origin.

Long-term neurodevelopmental outcome in conservatively treated congenital hyperinsulinism

BACKGROUND

Congenital hyperinsulinism (CH) is treated surgically in many centers (near-total and partial pancreatectomy for diffuse and focal disease respectively). Most patients treated with near-total pancreatectomy developed diabetes during childhood/puberty. CH patients are at increased risk of neurodevelopmental disorders, some being severe, which are reported to occur in 14-44% of patients from highly heterogenous cohorts. Over the last few decades, we have treated children with CH conservatively without surgery. The aim of this study was to assess the neurodevelopmental outcome of these patients.

DESIGN AND METHODS

The study included 21 Ashkenazi CH medically treated patients: 11 homozygotes (diffuse disease) and 9 heterozygotes with mutations on the paternal allele (presumed focal disease). The mean age was 13.7 years (range 8-23). Neurodevelopmental outcomes were assessed by telephone interviews of parents, using a standard questionnaire. Closest age siblings of CH patients served as controls.

RESULTS

Ten CH patients had perinatal seizures of short duration. Four had post-neonatal seizures, which remitted entirely. During early childhood, four patients (19%) had hypotonia, eight (38%) had fine motor problems, seven (33%) had gross motor problems (clumsiness), and one had mild cerebral palsy. Three patients (14%) had speech problems. Eight patients required developmental therapy, compared to one in the control group. Most of these problems were resolved by age 4-5 years. At school age, all were enrolled in regular education, some excelled in their studies, 6 out of 21 patients (29%) had learning problems (2 out of 21 controls). None had overt diabetes.

CONCLUSIONS

Good neurodevelopmental outcome was observed in our conservatively treated CH patients, with no diabetes as reported in patients undergoing pancreatectomy.

Prehistorically modified soils of central Amazonia: a model for sustainable agriculture in the twenty-first century

Terra Preta soils of central Amazonia exhibit approximately three times more soil organic matter, nitrogen and phosphorus and 70 times more charcoal compared to adjacent infertile soils. The Terra Preta soils were generated by pre-Columbian native populations by chance or intentionally adding large amounts of charred residues (charcoal), organic wastes, excrements and bones. In this paper, it is argued that generating new Terra Preta sites ('Terra Preta nova') could be the basis for sustainable agriculture in the twenty-first century to produce food for billions of people, and could lead to attaining three Millennium Development Goals: (i) to combat desertification, (ii) to sequester atmospheric CO2 in the long term, and (iii) to maintain biodiversity hotspots such as tropical rainforests. Therefore, large-scale generation and utilization of Terra Preta soils would decrease the pressure on primary forests that are being extensively cleared for agricultural use with only limited fertility and sustainability and, hence, only providing a limited time for cropping. This would maintain biodiversity while mitigating both land degradation and climate change. However, it should not be overlooked that the infertility of most tropical soils (and associated low population density) is what could have prevented tropical forests undergoing large-scale clearance for agriculture. Increased fertility may increase the populations supported by shifting cultivation, thereby maintaining and increasing pressure on forests.

Alkylphenols in sediments of the Atlantic Rainforest south-west of São Paulo, Brazil

Concentrations of technical 4-nonylphenol, 4-n-octylphenol, and 4-tert-octylphenol were investigated in surface water and sediment samples of four reservoirs southwest of São Paulo. Three of them (Takimoto 1, Takimoto 2, Pedro) were established in intensively cropped landscapes, one (Morro Grande) was surrounded by dense forests. Total alkylphenol concentrations in sediments generally ranged between 1 and 10 microgkg-1dw with 4-tert-octylphenol being the dominant alkylphenol. Because 4-tert-octylphenol concentration patterns at Takimoto 2, Pedro, and in the Morro Grande forest reservoir were found to be quite similar (upto 5 microgkg-1dw), this value is considered as the ubiquitous background level. In contrast, the Takimoto 1 sediments showed significantly higher 4-tert-octylphenol concentrations, possibly due to accelerated inputs from adjacent intensively cropped fields. Analysed alkylphenols were not detectable in water samples.