The Experts below are selected from a list of 13776 Experts worldwide ranked by ideXlab platform
Jeremy T Lundholm - One of the best experts on this subject based on the ideXlab platform.
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green roof plant species diversity improves ecosystem multifunctionality
Journal of Applied Ecology, 2015Co-Authors: Jeremy T LundholmAbstract:Summary Constructed ecosystems such as green roofs often contain monocultures or low-diversity plant communities, but adding more plant species to these systems can increase ecosystem service provisioning. Mixture advantage, when species-rich treatments outperform the best monocultures, is desirable in constructed ecosystems due to the cost of increasing diversity. However, there have not been any studies in constructed ecosystems that have quantitatively compared mixtures with the best monocultures for multifunctionality, and there have been few studies that have examined how provision of ecosystem services changes over time as plant communities develop. In a green roof system, I predicted (i) that the mixture advantage would be stronger for ecosystem multifunctionality than for single ecosystem functions and (ii) that ecosystem service provisioning and complementarity in above-ground biomass would increase over time. Fifteen monocultures of plant species from five life-form groups (succulents, tall Forbs, dwarf shrubs, creeping Forbs, grasses) were compared with three-species mixtures of the same life-form and mixtures of species from three and five different life-forms in a modular green roof system. Indicators of ecosystem services including above-ground production, thermal regulation, stormwater retention, nutrient uptake and carbon sequestration and two indices of ecosystem multifunctionality were compared. Canopy density increased over time while substrate temperature decreased, suggesting higher provisioning of valuable ecosystem services. For single services, the positive relationship between planted species richness and ecosystem service grew stronger over time, but was consistently strong over time for multifunctionality. Quantile regression indicated a weak mixture advantage for several services including both multifunctionality indices. While the effects were small, different species optimized different functions, thus multifunctioning is enhanced in more diverse mixtures by combining species that maximize different functions. Tripartite partitioning of canopy density showed that overyielding and trait-independent complementarity fluctuated between years in response to shifts in species abundances, but dominance and trait-dependent complementarity increased over time. Synthesis and applications. This study provides the first evidence in a constructed ecosystem that mixtures can outperform the best monocultures for multiple ecosystem services. Mixtures of plant life-forms can improve green roof performance. The biodiversity–ecosystem function relationships observed in natural ecosystems can also occur in novel and highly simplified engineered ecosystems.
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plant species and functional group combinations affect green roof ecosystem functions
PLOS ONE, 2010Co-Authors: Jeremy T Lundholm, Scott J Macivor, Zachary Macdougall, Melissa RanalliAbstract:Background Green roofs perform ecosystem services such as summer roof temperature reduction and stormwater capture that directly contribute to lower building energy use and potential economic savings. These services are in turn related to ecosystem functions performed by the vegetation layer such as radiation reflection and transpiration, but little work has examined the role of plant species composition and diversity in improving these functions. Methodology/Principal Findings We used a replicated modular extensive (shallow growing- medium) green roof system planted with monocultures or mixtures containing one, three or five life-forms, to quantify two ecosystem services: summer roof cooling and water capture. We also measured the related ecosystem properties/processes of albedo, evapotranspiration, and the mean and temporal variability of aboveground biomass over four months. Mixtures containing three or five life-form groups, simultaneously optimized several green roof ecosystem functions, outperforming monocultures and single life-form groups, but there was much variation in performance depending on which life-forms were present in the three life-form mixtures. Some mixtures outperformed the best monocultures for water capture, evapotranspiration, and an index combining both water capture and temperature reductions. Combinations of tall Forbs, grasses and succulents simultaneously optimized a range of ecosystem performance measures, thus the main benefit of including all three groups was not to maximize any single process but to perform a variety of functions well. Conclusions/Significance Ecosystem services from green roofs can be improved by planting certain life-form groups in combination, directly contributing to climate change mitigation and adaptation strategies. The strong performance by certain mixtures of life-forms, especially tall Forbs, grasses and succulents, warrants further investigation into niche complementarity or facilitation as mechanisms governing biodiversity-ecosystem functioning relationships in green roof ecosystems.
Anja K Bielinsky - One of the best experts on this subject based on the ideXlab platform.
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functional cross talk between the fanconi anemia and atrx daxx histone chaperone pathways promotes replication fork recovery
Human Molecular Genetics, 2020Co-Authors: Maya Raghunandan, Jung Eun Yeo, Ryan Walter, Kai Saito, Adam J Harvey, Stacie Ittershagen, Euna Lee, Jihyeon Yang, Maureen E Hoatlin, Anja K BielinskyAbstract:Fanconi anemia (FA) is a chromosome instability syndrome characterized by increased cancer predisposition. Specifically, the FA pathway functions to protect genome stability during DNA replication. The central FA pathway protein, FANCD2, locates to stalled replication forks and recruits homologous recombination (HR) factors such as CtBP interacting protein (CtIP) to promote replication fork restart while suppressing new origin firing. Here, we identify alpha-thalassemia retardation syndrome X-linked (ATRX) as a novel physical and functional interaction partner of FANCD2. ATRX is a chromatin remodeler that forms a complex with Death domain-associated protein 6 (DAXX) to deposit the histone variant H3.3 into specific genomic regions. Intriguingly, ATRX was recently implicated in replication fork recovery; however, the underlying mechanism(s) remained incompletely understood. Our findings demonstrate that ATRX forms a constitutive protein complex with FANCD2 and protects FANCD2 from proteasomal degradation. ATRX and FANCD2 localize to stalled replication forks where they cooperate to recruit CtIP and promote MRE11 exonuclease-dependent fork restart while suppressing the firing of new replication origins. Remarkably, replication restart requires the concerted histone H3 chaperone activities of ATRX/DAXX and FANCD2, demonstrating that coordinated histone H3 variant deposition is a crucial event during the reinitiation of replicative DNA synthesis. Lastly, ATRX also cooperates with FANCD2 to promote the HR-dependent repair of directly induced DNA double-stranded breaks. We propose that ATRX is a novel functional partner of FANCD2 to promote histone deposition-dependent HR mechanisms in S-phase.
Michael T Laub - One of the best experts on this subject based on the ideXlab platform.
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a bacterial chromosome structuring protein binds overtwisted dna to stimulate type ii topoisomerases and enable dna replication
Cell, 2018Co-Authors: Monica S Guo, Diane Laure Haakonsen, Wenjie Zeng, Maria A Schumacher, Michael T LaubAbstract:Summary When DNA is unwound during replication, it becomes overtwisted and forms positive supercoils in front of the translocating DNA polymerase. Unless removed or dissipated, this superhelical tension can impede replication elongation. Topoisomerases, including gyrase and topoisomerase IV in bacteria, are required to relax positive supercoils ahead of DNA polymerase but may not be sufficient for replication. Here, we find that GapR, a chromosome structuring protein in Caulobacter crescentus, is required to complete DNA replication. GapR associates in vivo with positively supercoiled chromosomal DNA, and our biochemical and structural studies demonstrate that GapR forms a dimer-of-dimers that fully encircles overtwisted DNA. Further, we show that GapR stimulates gyrase and topo IV to relax positive supercoils, thereby enabling DNA replication. Analogous chromosome structuring proteins that locate to the overtwisted DNA in front of replication forks may be present in other organisms, similarly helping to recruit and stimulate topoisomerases during DNA replication.
Sabine Güsewell - One of the best experts on this subject based on the ideXlab platform.
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Invasive Forbs differ functionally from native graminoids, but are similar to native Forbs.
The New phytologist, 2010Co-Authors: Deborah Scharfy, Andrea Funk, Harry Olde Venterink, Sabine GüsewellAbstract:Summary •Exotic plant invasions can alter ecosystem processes, particularly if the invasive species are functionally different from native species. We investigated whether such alterations can be explained by differences in functional traits between native and invasive plants of the same functional group or by differences in functional group affiliation. •We compared six invasive Forbs in Europe with six native Forbs and six native graminoids in leaf and whole-plant traits, plasticity in response to nutrient supply and interspecific competition, litter decomposition rate, effects on soil nutrient availability, and allelopathy. All traits were measured in a series of pot experiments, and leaf traits additionally in the field. •Invasive Forbs differed from native Forbs for only a few traits; they had less leaf chlorophyll and lower phosphorus (P) uptake from soil, but they tended to have a stronger allelopathic effect. The invasive Forbs differed in many traits from the native graminoids, their leaves had lower tissue densities and a shorter life span, their litter decomposed faster and they had a lower nitrogen-use efficiency. •Our results suggest that invasive Forbs have the potential to alter ecosystem properties when invading graminoid-dominated and displacing native graminoids but not when displacing native Forbs.
Maya Raghunandan - One of the best experts on this subject based on the ideXlab platform.
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functional cross talk between the fanconi anemia and atrx daxx histone chaperone pathways promotes replication fork recovery
Human Molecular Genetics, 2020Co-Authors: Maya Raghunandan, Jung Eun Yeo, Ryan Walter, Kai Saito, Adam J Harvey, Stacie Ittershagen, Euna Lee, Jihyeon Yang, Maureen E Hoatlin, Anja K BielinskyAbstract:Fanconi anemia (FA) is a chromosome instability syndrome characterized by increased cancer predisposition. Specifically, the FA pathway functions to protect genome stability during DNA replication. The central FA pathway protein, FANCD2, locates to stalled replication forks and recruits homologous recombination (HR) factors such as CtBP interacting protein (CtIP) to promote replication fork restart while suppressing new origin firing. Here, we identify alpha-thalassemia retardation syndrome X-linked (ATRX) as a novel physical and functional interaction partner of FANCD2. ATRX is a chromatin remodeler that forms a complex with Death domain-associated protein 6 (DAXX) to deposit the histone variant H3.3 into specific genomic regions. Intriguingly, ATRX was recently implicated in replication fork recovery; however, the underlying mechanism(s) remained incompletely understood. Our findings demonstrate that ATRX forms a constitutive protein complex with FANCD2 and protects FANCD2 from proteasomal degradation. ATRX and FANCD2 localize to stalled replication forks where they cooperate to recruit CtIP and promote MRE11 exonuclease-dependent fork restart while suppressing the firing of new replication origins. Remarkably, replication restart requires the concerted histone H3 chaperone activities of ATRX/DAXX and FANCD2, demonstrating that coordinated histone H3 variant deposition is a crucial event during the reinitiation of replicative DNA synthesis. Lastly, ATRX also cooperates with FANCD2 to promote the HR-dependent repair of directly induced DNA double-stranded breaks. We propose that ATRX is a novel functional partner of FANCD2 to promote histone deposition-dependent HR mechanisms in S-phase.