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Unfolding admixed ancestry and genomic diversity in zoo giraffes
No full textA giraffe nicknamed Marius attracted international media attention and world-wide notoriety when euthanized by Copenhagen Zoo in 2014, deemed surplus to the European breeding program. This incident highlights the challenges of managing zoo populations to best contribute to species conservation amid limited resources. Here, we investigated the degree of admixture, genetic diversity and inbreeding in ex situ giraffes using whole genome sequencing data from Marius and 12 other zoo giraffes, leveraging a reference data set from 71 wild giraffes. We found that most zoo giraffes show admixed ancestries. Marius, and zoo individuals assigned to Reticulated giraffes, exhibits mosaic ancestry with 85% Reticulated and 15% Nubian origin. We further detected recent inbreeding in some of the zoo individuals, consistent with their studbook data. Runs of homozygosity revealed that Marius and three other zoo giraffes were more inbred than their wild counterparts, although their admixed ancestry compensates for the reduction in genetic diversity caused by inbreeding. Our findings highlight the dual challenges of admixture and inbreeding in ex situ populations of giraffe, emphasizing the need for balanced genetic management to mitigate inbreeding and outbreeding depression while preserving diversity reflective of wild populations. This study also reinforces the importance of studbooks and genomic tools in guiding ex situ conservation strategies
Short-term effects of Greenlandic glacial rock flour on soil physical properties and maize yield
No full textGreenlandic glacial rock flour (GRF) serves as a valuable source of silicate minerals for CO₂ uptake through enhanced weathering. Additionally, its physico-chemical properties may influence soil hydro-physical characteristics and may also have a separate effect on crop yields. This study evaluated the effects of GRF application at 50 and 100 t/ha, along with an unamended control, on soil water content at field capacity (FC), plant-available water (PAW), saturated hydraulic conductivity (Ksat), and dry aggregate stability (DAS) over 120 days. Separately, maize dry matter yield (DMY) was assessed after 40 days of growth. The experiment was conducted across four soil textures, comprising coarse-textured soils (sand and sandy loam) and fine-textured soils (sandy clay loam and clay). The 100 t/ha application had the most significant (p < 0.05) impact on soil properties and maize yield, while the 50 t/ha rate showed intermediate but inconsistent effects. In fine-textured soils, the 100 t/ha treatment increased FC by 15% and PAW by 27% compared to the control, whereas in coarse-textured soils, FC and PAW rose by 29% and 26%, respectively. However, Ksat decreased by 47% in fine-textured soils and 34% in coarse-textured soils compared to the control. Maize DMY for the 100 t/ha rate increased by 18% in coarse-textured soils and 38% in fine-textured soils relative to the control. These findings suggest that GRF amendment improved hydro-physical properties more in coarse-textured soils but increased yield more in fine-textured soils, and may serve as a useful co-benefit of enhanced rock weathering.</p
Human disturbance intensity reduces drought resistance without prolonging recovery in karst forests of southwest China
No full textRole of human disturbance in shaping forest drought responses remains insufficiently understood, particularly in widely-distributed and ecologically-fragile karst landscapes. Here, we analyzed six major drought events over the past two decades in the karst forests of Southwest China, a region representative of tropical and subtropical karst ecosystems with intensive human activity. Using high-resolution gross primary productivity (GPP) and Standardized Precipitation Evapotranspiration Index (SPEI) datasets, we compared drought resistance and recovery time between low- and high-disturbance forests. High-disturbance forests experienced significantly greater maximum GPP losses during droughts, with differences reaching up to 13% under comparable drought intensities. Beyond the dominant influence of drought intensity, climatic conditions (temperature and precipitation) and soil factors (soil organic carbon and soil thickness) exerted stronger effects on drought-induced GPP loss in high-disturbance forests than in low-disturbance ones. Interestingly, despite suffering greater productivity loss, high-disturbance forests exhibited comparable, and occasionally even shorter, recovery times than low-disturbance forests, suggesting a possible trade-off between drought resistance and recovery capacity. Although recovery time was not consistently prolonged, the greater productivity losses and elevated climatic and edaphic sensitivity in high-disturbance forests indicate reduced resistance and heightened vulnerability to future climate extremes and progressive drying trends
Cross-National Validation of the WHO-5 Well-Being Index Within Adolescent Populations:Findings From 43 Countries
No full textThe five-item World Health Organization Well-Being Index (WHO-5) is among the most frequently used brief standard measures to assess hedonic well-being. Numerous studies have investigated different facets of its psychometric properties in adult populations. However, whether these results apply to adolescents is uncertain, and only few psychometric studies employed adolescent populations. Thus, the current study aimed to conduct an in-depth psychometric item response theory analysis of the WHO-5 among adolescents from 43 countries using the Health Behaviour in School-aged Children (HBSC) 2022 data set and investigated its (a) dimensionality and measurement structure, (b) test information values and marginal reliability, (c) cross-country measurement invariance and differential item/test functioning, and (d) convergent validity with other measures related to mental health and well-being across countries. The WHO-5 showed a unidimensional measurement structure and overall high test information values and marginal reliability. Furthermore, although a large proportion of parameters were flagged as non-invariant, differential test functioning of the WHO-5 was only modest. Moreover, the WHO-5 mainly showed a concurring nomological network with the other measures related to mental health and well-being across countries, although with some differences in effect sizes. The WHO-5 Well-Being Index is a psychometrically sound measure that has shown promise for cross-cultural research among adolescents in the included European, Central Asia, and North American countries. The translated versions of the WHO-5 are available at https://osf.io/pbexq.The five-item World Health Organization Well-Being Index (WHO-5) is among the most frequently used brief standard measures to assess hedonic well-being. Numerous studies have investigated different facets of its psychometric properties in adult populations. However, whether these results apply to adolescents is uncertain, and only few psychometric studies employed adolescent populations. Thus, the current study aimed to conduct an in-depth psychometric item response theory analysis of the WHO-5 among adolescents from 43 countries using the Health Behaviour in School-aged Children (HBSC) 2022 data set and investigated its (a) dimensionality and measurement structure, (b) test information values and marginal reliability, (c) cross-country measurement invariance and differential item/test functioning, and (d) convergent validity with other measures related to mental health and well-being across countries. The WHO-5 showed a unidimensional measurement structure and overall high test information values and marginal reliability. Furthermore, although a large proportion of parameters were flagged as non-invariant, differential test functioning of the WHO-5 was only modest. Moreover, the WHO-5 mainly showed a concurring nomological network with the other measures related to mental health and well-being across countries, although with some differences in effect sizes. The WHO-5 Well-Being Index is a psychometrically sound measure that has shown promise for cross-cultural research among adolescents in the included European, Central Asia, and North American countries. The translated versions of the WHO-5 are available at https://osf.io/pbexq.</p
Genetically heterozygous - transcriptionally homozygous IRF7 deficiency underlies herpesvirus CNS infections in humans
No full textInborn errors of immunity (IEI) impairing brain-intrinsic immune defenses can underlie herpes simplex virus encephalitis. By whole-exome sequencing of cohorts of herpesvirus-associated recurrent lymphocytic meningitis and acute retinal necrosis, we identified two patients heterozygous for variants in interferon (IFN) regulatory factor 7 (IRF7). The expression of the Q185X (patient 1, P1) and A86Rfs23X (P2) IRF7 variants in HEK293T cells resulted in truncated IRF7 proteins that lacked IFN-transactivating ability. Peripheral blood mononuclear cells from P1 exhibited reduced type I IFN responses to HSV-2 infection. Genetic knock-in of the IRF7 Q185X variant in THP-1 cells and stem cell-derived plasmacytoid dendritic cells (pDC) confirmed the disrupted IFN expression, resulting in impaired paracrine antiviral protection of meningeal fibroblasts. Strikingly, genetically heterozygous index patient pDC, but not those of healthy carrier family members, showed expression of only the pathogenic IRF7 Q185X allele, resulting in a homozygous transcriptotype. Collectively, this study identifies genetically heterozygous but transcriptionally homozygous IRF7 deficiency as an IEI underlying herpesvirus central nervous system infection
Exercise and hypoxia independently stimulate platelet liberation of brain-derived neurotrophic factor and platelet factor 4
No full textBrain-derived neurotrophic factor (BDNF) is an essential mediator of exercise-induced neuroplasticity. The majority of BDNF in circulation (similar to 99%) is stored bound to platelets. Platelet activation by exercise stimulates the release of their contents, representing a dynamic, bioavailable pool of BDNF. Hypoxia also independently activates platelets; therefore the combination of these stressors provides a unique model to examine the role of platelets in liberating BDNF and to quantify its flux across the brain during exercise. Twelve healthy adults (six women; 28 +/- 4 years) performed exercise to exhaustion at sea level (340 m) and after 6-8 days at high altitude (3800 m) in a repeated-measures cross-over design. Simultaneous radial arterial and internal jugular venous blood samples were collected within the last 2 min of maximal exercise to quantify BDNF across the brain, alongside platelet concentration and platelet factor 4 (PF4), another neurogenic factor and a biomarker of platelet activation. At sea level, maximal exercise doubled free BDNF (P < 0.001) with no difference between arterial and venous circulations (P = 0.849). At high altitude, there was a pronounced veno-arterial difference indicating net release of BDNF (P = 0.003), and in addition, exercise caused a similar doubling in free BDNF (P < 0.001). Platelet concentration decreased by a third across the brain with exercise at high altitude (P = 0.002), but not sea level, and PF4 release was strongly correlated with BDNF release (r = 0.61, P < 0.001). Platelet activation across the human brain during exercise and hypoxia liberates BDNF and PF4 and may contribute to the neurotrophic effect of exercise
deadtrees.earth — An open-access and interactive database for centimeter-scale aerial imagery to uncover global tree mortality dynamics
No full textExcessive tree mortality is a global concern and remains poorly understood as it is a complex phenomenon. We lack global and temporally continuous coverage on tree mortality data. Ground-based observations on tree mortality, e.g., derived from national inventories, are very sparse, and may not be standardized or spatially explicit. Earth observation data, combined with supervised machine learning, offer a promising approach to map overstory tree mortality in a consistent manner over space and time. However, global-scale machine learning requires broad training data covering a wide range of environmental settings and forest types. Low altitude observation platforms (e.g., drones or airplanes) provide a cost-effective source of training data by capturing high-resolution orthophotos of overstory tree mortality events at centimeter-scale resolution. Here, we introduce deadtrees.earth, an open-access platform hosting more than two thousand centimeter-resolution orthophotos, covering more than 1,000,000 ha, of which more than 58,000 ha are manually annotated with live/dead tree classifications. This community-sourced and rigorously curated dataset can serve as a comprehensive reference dataset to uncover tree mortality patterns from local to global scales using space-based Earth observation data and machine learning models. This will provide the basis to attribute tree mortality patterns to environmental changes or project tree mortality dynamics to the future. The open nature of deadtrees.earth, together with its curation of high-quality, spatially representative, and ecologically diverse data will continuously increase our capacity to uncover and understand tree mortality dynamics.</p