Fatores edáficos determinando a ocorrência de leguminosas herbáceas em savanas amazônicas

Fatores edáficos vem sendo indicados como determinantes para a distribuição de comunidades de plantas na Amazônia. O objetivo deste estudo foi investigar quais fatores edáficos determinam a ocorrência de leguminosas herbáceas em savanas amazônicas. Para tanto, foi realizado um inventário da flora herbácea da família Leguminosae em 34 parcelas permanentes estabelecidas em duas áreas de savana de Roraima, norte da Amazônia brasileira. As espécies Chamaecrista desvauxii (24,9%), Aeschynomene histrix (15,7%) e Galactia jussiaeana (10,8%) foram as de maior índice de valor de importância. Todas com grande abundância e ampla distribuição. Os resultados indicaram baixa densidade ou ausência de indivíduos e espécies em parcelas estabelecidas em solos mal drenados (hidromórficos). Diversidade e riqueza de espécies tendeu a ser maior em habitats formados por solos bem drenados, mais férteis e com menor concentração de alumínio trocável. É sugerido que solos pobres e sazonalmente alagados reduzam as chances de ocorrência e afetem negativamente a riqueza/diversidade de leguminosas herbáceas nas áreas de savana de Roraima

Genome-wide interaction study of a proxy for stress-sensitivity and its prediction of major depressive disorder

Individual response to stress is correlated with neuroticism and is an important predictor of both neuroticism and the onset of major depressive disorder (MDD). Identification of the genetics underpinning individual differences in response to negative events (stress-sensitivity) may improve our understanding of the molecular pathways involved, and its association with stress-related illnesses. We sought to generate a proxy for stress-sensitivity through modelling the interaction between SNP allele and MDD status on neuroticism score in order to identify genetic variants that contribute to the higher neuroticism seen in individuals with a lifetime diagnosis of depression compared to unaffected individuals. Meta-analysis of genome-wide interaction studies (GWIS) in UK Biobank (N = 23,092) and Generation Scotland: Scottish Family Health Study (N = 7,155) identified no genome-wide significance SNP interactions. However, gene-based tests identified a genome-wide significant gene, ZNF366, a negative regulator of glucocorticoid receptor function implicated in alcohol dependence (p = 1.48x10-7; Bonferroni-corrected significance threshold p < 2.79x10-6). Using summary statistics from the stress-sensitivity term of the GWIS, SNP heritability for stress-sensitivity was estimated at 5.0%. In models fitting polygenic risk scores of both MDD and neuroticism derived from independent GWAS, we show that polygenic risk scores derived from the UK Biobank stress-sensitivity GWIS significantly improved the prediction of MDD in Generation Scotland. This study may improve interpretation of larger genome-wide association studies of MDD and other stress-related illnesses, and the understanding of the etiological mechanisms underpinning stress-sensitivity

Shared genetic risk between eating disorder- and substance-use-related phenotypes:Evidence from genome-wide association studies

First published: 16 February 202

Age at first birth in women is genetically associated with increased risk of schizophrenia

Prof. Paunio on PGC:n jäsenPrevious studies have shown an increased risk for mental health problems in children born to both younger and older parents compared to children of average-aged parents. We previously used a novel design to reveal a latent mechanism of genetic association between schizophrenia and age at first birth in women (AFB). Here, we use independent data from the UK Biobank (N = 38,892) to replicate the finding of an association between predicted genetic risk of schizophrenia and AFB in women, and to estimate the genetic correlation between schizophrenia and AFB in women stratified into younger and older groups. We find evidence for an association between predicted genetic risk of schizophrenia and AFB in women (P-value = 1.12E-05), and we show genetic heterogeneity between younger and older AFB groups (P-value = 3.45E-03). The genetic correlation between schizophrenia and AFB in the younger AFB group is -0.16 (SE = 0.04) while that between schizophrenia and AFB in the older AFB group is 0.14 (SE = 0.08). Our results suggest that early, and perhaps also late, age at first birth in women is associated with increased genetic risk for schizophrenia in the UK Biobank sample. These findings contribute new insights into factors contributing to the complex bio-social risk architecture underpinning the association between parental age and offspring mental health.Peer reviewe

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time, and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space. While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes, vast areas of the tropics remain understudied. In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity, but it remains among the least known forests in America and is often underrepresented in biodiversity databases. To worsen this situation, human-induced modifications may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge, it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

The genetics of the mood disorder spectrum:genome-wide association analyses of over 185,000 cases and 439,000 controls

Background Mood disorders (including major depressive disorder and bipolar disorder) affect 10-20% of the population. They range from brief, mild episodes to severe, incapacitating conditions that markedly impact lives. Despite their diagnostic distinction, multiple approaches have shown considerable sharing of risk factors across the mood disorders. Methods To clarify their shared molecular genetic basis, and to highlight disorder-specific associations, we meta-analysed data from the latest Psychiatric Genomics Consortium (PGC) genome-wide association studies of major depression (including data from 23andMe) and bipolar disorder, and an additional major depressive disorder cohort from UK Biobank (total: 185,285 cases, 439,741 controls; non-overlapping N = 609,424). Results Seventy-three loci reached genome-wide significance in the meta-analysis, including 15 that are novel for mood disorders. More genome-wide significant loci from the PGC analysis of major depression than bipolar disorder reached genome-wide significance. Genetic correlations revealed that type 2 bipolar disorder correlates strongly with recurrent and single episode major depressive disorder. Systems biology analyses highlight both similarities and differences between the mood disorders, particularly in the mouse brain cell-types implicated by the expression patterns of associated genes. The mood disorders also differ in their genetic correlation with educational attainment – positive in bipolar disorder but negative in major depressive disorder. Conclusions The mood disorders share several genetic associations, and can be combined effectively to increase variant discovery. However, we demonstrate several differences between these disorders. Analysing subtypes of major depressive disorder and bipolar disorder provides evidence for a genetic mood disorders spectrum

Rapid vegetation succession and coupled permafrost dynamics in arctic thaw ponds in the Siberian lowland tundra

Thermokarst features, such as thaw ponds, are hotspots for methane emissions in warming lowland tundra. Presently we lack quantitative knowledge on the formation rates of formation of thaw ponds and subsequent vegetation succession, necessary to determine their net contribution to greenhouse gas emissions. This study set out to identify development trajectories and formation rates approximate rates of of small-scale (< 1 km2) arctic thaw ponds in north-eastern Siberia. We selected 40 ponds of different age classes based on a time-series of satellite images and measured vegetation composition, microtopography, water table and active layer thicknessthaw depth in the field and measured age of recruiting colonizing shrubs in thaw ponds using dendrochronology. We found that young thaw ponds are characterised by dead shrubs, while older ponds show rapid paludification through colonization bycontain mostly sedges and Sphagnum moss. While dead shrubs and open water are associated with permafrost degradation (lower surface elevation, high active layer thicknesslarger thaw depth), sites with sedge and in particular Sphagnum display indications of permafrost recovery. Recruitment of Betula nana on Sphagnum carpets in ponds indicates a potential recovery towards shrub dominated vegetation, although it remains unclear if and on what timescale this occurs. Our results suggest that thaw ponds display potentially cyclic vegetation succession associated with permafrost degradation and recovery. Thaw pond formation and initial colonization by sedges can occur on subdecadal timescales, which is relatively fast compared to rates known for ice wedge degradation (subdecadal to century-scale). The rates of formation and recovery of small-scale thaw ponds have implications for the greening/browning dynamics and carbon balance of this ecosystem

Rapid vegetation succession and coupled permafrost dynamics in arctic thaw ponds in the Siberian lowland tundra

Thermokarst features, such as thaw ponds, are hotspots for methane emissions in warming lowland tundra. Presently we lack quantitative knowledge on the formation rates of formation of thaw ponds and subsequent vegetation succession, necessary to determine their net contribution to greenhouse gas emissions. This study set out to identify development trajectories and formation rates approximate rates of of small-scale (< 1 km2) arctic thaw ponds in north-eastern Siberia. We selected 40 ponds of different age classes based on a time-series of satellite images and measured vegetation composition, microtopography, water table and active layer thicknessthaw depth in the field and measured age of recruiting colonizing shrubs in thaw ponds using dendrochronology. We found that young thaw ponds are characterised by dead shrubs, while older ponds show rapid paludification through colonization bycontain mostly sedges and Sphagnum moss. While dead shrubs and open water are associated with permafrost degradation (lower surface elevation, high active layer thicknesslarger thaw depth), sites with sedge and in particular Sphagnum display indications of permafrost recovery. Recruitment of Betula nana on Sphagnum carpets in ponds indicates a potential recovery towards shrub dominated vegetation, although it remains unclear if and on what timescale this occurs. Our results suggest that thaw ponds display potentially cyclic vegetation succession associated with permafrost degradation and recovery. Thaw pond formation and initial colonization by sedges can occur on subdecadal timescales, which is relatively fast compared to rates known for ice wedge degradation (subdecadal to century-scale). The rates of formation and recovery of small-scale thaw ponds have implications for the greening/browning dynamics and carbon balance of this ecosystem