ABSTRACT
Spinal motor neurons (MNs) represent a highly vulnerable cellular population, which is affected in fatal neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA). In this study, we show that the heterozygous loss of SYT13 is sufficient to trigger a neurodegenerative phenotype resembling those observed in ALS and SMA. SYT13+/- hiPSC-derived MNs displayed a progressive manifestation of typical neurodegenerative hallmarks such as loss of synaptic contacts and accumulation of aberrant aggregates. Moreover, analysis of the SYT13+/- transcriptome revealed a significant impairment in biological mechanisms involved in motoneuron specification and spinal cord differentiation. This transcriptional portrait also strikingly correlated with ALS signatures, displaying a significant convergence toward the expression of pro-apoptotic and pro-inflammatory genes, which are controlled by the transcription factor TP53. Our data show for the first time that the heterozygous loss of a single member of the synaptotagmin family, SYT13, is sufficient to trigger a series of abnormal alterations leading to MN sufferance, thus revealing novel insights into the selective vulnerability of this cell population.
Subject(s)
Amyotrophic Lateral Sclerosis , Motor Neurons , Synaptotagmins , Tumor Suppressor Protein p53 , Humans , Tumor Suppressor Protein p53/metabolism , Tumor Suppressor Protein p53/genetics , Motor Neurons/metabolism , Motor Neurons/pathology , Synaptotagmins/metabolism , Synaptotagmins/genetics , Amyotrophic Lateral Sclerosis/genetics , Amyotrophic Lateral Sclerosis/metabolism , Amyotrophic Lateral Sclerosis/pathology , Heterozygote , Phenotype , Induced Pluripotent Stem Cells/metabolism , Induced Pluripotent Stem Cells/pathology , Cell Differentiation/genetics , Gene Knockout TechniquesABSTRACT
Soil organic carbon (SOC) plays a vital role in global carbon cycling and sequestration, underpinning the need for a comprehensive understanding of its distribution and controls. This study explores the importance of various covariates on SOC spatial distribution at both local (up to 1.25 km) and continental (USA) scales using a deep learning approach. Our findings highlight the significant role of terrain attributes in predicting SOC concentration distribution with terrain, contributing approximately one-third of the overall prediction at the local scale. At the continental scale, climate is only 1.2 times more important than terrain in predicting SOC distribution, whereas at the local scale, the structural pattern of terrain is 14 and 2 times more important than climate and vegetation, respectively. We underscore that terrain attributes, while being integral to the SOC distribution at all scales, are stronger predictors at the local scale with explicit spatial arrangement information. While this observational study does not assess causal mechanisms, our analysis nonetheless presents a nuanced perspective about SOC spatial distribution, which suggests disparate predictors of SOC at local and continental scales. The insights gained from this study have implications for improved SOC mapping, decision support tools, and land management strategies, aiding in the development of effective carbon sequestration initiatives and enhancing climate mitigation efforts.
Subject(s)
Carbon , Climate , Soil , Soil/chemistry , Carbon Cycle , Carbon SequestrationABSTRACT
Reactive Oxygen Species (ROS) derived from mitochondrial respiration are frequently cited as a major source of chromosomal DNA mutations that contribute to cancer development and aging. However, experimental evidence showing that ROS released by mitochondria can directly damage nuclear DNA is largely lacking. In this study, we investigated the effects of H2O2 released by mitochondria or produced at the nucleosomes using a titratable chemogenetic approach. This enabled us to precisely investigate to what extent DNA damage occurs downstream of near- and supraphysiological amounts of localized H2O2. Nuclear H2O2 gives rise to DNA damage and mutations and a subsequent p53 dependent cell cycle arrest. Mitochondrial H2O2 release shows none of these effects, even at levels that are orders of magnitude higher than what mitochondria normally produce. We conclude that H2O2 released from mitochondria is unlikely to directly damage nuclear genomic DNA, limiting its contribution to oncogenic transformation and aging.
Subject(s)
Hydrogen Peroxide , Mitochondria , Reactive Oxygen Species/metabolism , Hydrogen Peroxide/metabolism , Mitochondria/metabolism , DNA/metabolism , DNA Damage , DNA, Mitochondrial/genetics , DNA, Mitochondrial/metabolismABSTRACT
Long term applications of leguminous green mulch could increase mineralizable nitrogen (N) beneath cupuaçu trees produced on the infertile acidic Ultisols and Oxisols of the Amazon Basin. However, low quality standing cupuaçu litter could interfere with green mulch N release and soil N mineralization. This study compared mineral N, total N, and microbial biomass N beneath cupuaçu trees grown in two different agroforestry systems, north of Manaus, Brazil, following seven years of different green mulch application rates. To test for net interactions between green mulch and cupuaçu litter, dried gliricidia and inga leaves were mixed with senescent cupuaçu leaves, surface applied to an Oxisol soil, and incubated in a greenhouse for 162 days. Leaf decomposition, N release and soil N mineralization were periodically measured in the mixed species litter treatments and compared to single species applications. The effect of legume biomass and cupuaçu litter on soil mineral N was additive implying that recommendations for green mulch applications to cupuaçu trees can be based on N dynamics of individual green mulch species. Results demonstrated that residue quality, not quantity, was the dominant factor affecting the rate of N release from leaves and soil N mineralization in a controlled environment. In the field, complex N cycling and other factors, including soil fauna, roots, and microclimatic effects, had a stronger influence on available soil N than residue quality.
Aplicações a longo prazo de leguminosas como adubo verde podem aumentar o nitrogênio (N) mineralizável sob árvores de cupuaçu em solos pouco férteis e ácidos (Ultisols e Oxisols) da Bacia Amazônica. Entretanto, a baixa qualidade da liteira de cupuaçu pode influênciara liberação de N do adubo verde e a mineralização deste no solo. Neste estudo foram comparados o N mineral, N total, e o N da biomassa microbiana sob árvores de cupuaçu cultivadas em dois sistemas agroflorestais, ao norte de Manaus, Brasil, as quais receberam diferentes aplicações de adubo verde sob sua liteira natural durante sete anos. Para testar as interações entre o adubo verde e a liteira de cupuaçu, folhas secas de gliricídia e ingá foram misturadas com as folhas senescentes de cupuaçu, distribuídas na superfície de um solo Oxisol, e incubadas em casa de vegetação durante 162 dias. A decomposição das folhas, a liberação de N e mineralização do N no solo foram periodicamente mensurados nos tratamentos de mistura de liteira de diferentes espécies e comparados com as aplicações de liteira de apenas uma espécie. O efeito da biomassa de leguminosas e da liteira de cupuaçu no N mineral do solo foi aditivo, indicando que o uso de adubação verde em plantas de cupuaçu pode ser baseado na dinâmica do N em cada espécie usada como adubo verde. Os resultados demonstraram que a qualidade do resíduo, e não a quantidade, foi o principal fator que influenciou a taxa de liberação de N das folhas e a mineralização deste no solo, em ambiente controlado. No campo, o complexo ciclo do N e outros fatores tais como a fauna do solo, raízes e os efeitos do microclima, tiveram uma influência mais forte na disponibilidade de N no solo do que a qualidade d o resíduo vegetal.
Subject(s)
Soil , Forestry , Fruit , FabaceaeABSTRACT
Fruit tree production is gaining an increasing importance in the central Amazon and elsewhere in the humid tropics, but very little is known about the nutrient dynamics in the soil-plant system. The present study quantified the effects of fertilization and cover cropping with a legume (Pueraria phaseoloides (Roxb.) Benth.) on soil nitrogen (N) dynamics and plant nutrition in a young guarana plantation (Paullinia cupana Kunth. (H.B. and K.) var. sorbilis (Mart.) Ducke) on a highly weathered Xanthic Ferralsol. Large subsoil nitrate (NO3-) accumulation at 0.3-3 m below the guarana plantation indicated N leaching from the topsoil. The NO3- contents to a depth of 2 m were 2.4 times greater between the trees than underneath unfertilized trees (P<0.05). The legume cover crop between the trees increased soil N availability as shown by elevated aerobic N mineralization and lower N immobilization in microbial biomass. The guarana N nutrition and yield did not benefit from the N input by biological fixation of atmospheric N2 by the legume cover (P>0.05). Even without a legume intercrop, large amounts of NO3- were found in the subsoil between unfertilized trees. Subsoil NO3- between the trees could be utilized, however, by fertilized guarana. This can be explained by a more vigorous growth of fertilized trees which had a larger nutrient demand and exploited a larger soil volume. With a legume cover crop, however, more mineral N was available at the topsoil which was leached into the subsoil and consequently accumulated at 0.3-3 m depth. Fertilizer additions of P and K were needed to increase subsoil NO3- use between trees.
A produção de fruteiras está ganhando grande importância na Amazônia Central e em outras partes dos trópicos úmidos mas, muito pouco ainda é conhecido sobre a dinâmica de nutrientes no sistema solo-planta. O presente estudo quantificou os efeitos da fertilização mineral e da cobertura do solo com uma leguminosa (Pueraria phaseoloides (Roxb) Benth.) sobre a dinâmica do N no solo e sobre a nutrição de plantas jovens de guaraná (Paullinia cupana Kunth. (H.B. and K.) var. sorbilis (Mart.) Ducke), em um Latossolo Amarelo muito argiloso. Grande acúmulo de nitrato (NO3-) encontrado na profundidade de 0,3 - 3,0m abaixo do plantio de guaraná é um indicativo da lixiviação de N da camada superficial. Os teores de NO3- na profundidade de 2m era 2,4 vezes maior entre as plantas do que na entrelinha que não recebeu fertilização (P<0,05). A leguminosa de cobertura, entre as plantas de guaraná, aumentou a disponibilidade de N, conforme é indicado pela elevada mineralização aeróbica e baixa imobilização de N na massa microbiana. A nutrição nitrogenada e a produção do guaraná não foram beneficiados pela adição de N, via fixação biológica do N2 da atmosfera pela leguminosa de cobertura (P<0,05). Mesmo sem leguminosa nas entrelinhas de plantio, grandes quantidades de NO3- foram encontradas no subsolo, entre plantas não adubadas. O NO3- do subsolo entre as plantas pode, entretanto, ter sido utilizado pelo guaraná fertilizado. Isso pode ser explicado pelo crescimento mais vigoroso das plantas fertilizadas as quais têm uma grande demanda por nutrientes e exploraram maior volume de solo. Com uma leguminosa de cobertura, contudo, mais N mineral foi disponibilizado na camada superficial, o qual foi lixiviado para o subsolo e, consequentemente, acumulado na camada de 0,3 a 3,0m de profundidade. Adições suplementares de P e K foram necessárias para aumentar a utilização do NO3- entre as plantas.