46 research outputs found
Growth pattern of Fortunian scalidophoran sclerites
Fortunian scalidophoran worms have shown high diversity, with 7 genera and species and 10 indeterminate forms. Current studies have mainly focused on morphology as well as early evolution, and studies on ontogeny have not been carried out due to the limited number of specimens. Here, we report new material of an Orsten-type preserved Indeterminate Form 3 from the Zhangjiagou section. Collected specimens of Indeterminate Form 3 with different annulus widths indicate the presence of several ontogenetic stages. We found newly formed sclerites on the annulus of Indeterminate Form 3 at different ontogenetic stages, suggesting that the sclerites of Indeterminate Form 3 become more numerous in addition to increasing in size during growth. The size of the large sclerites may also increase as the worms grow, however, their number may not change
Cadmium Treatment Alters the Expression of Five Genes at the Cda1
Westag 97 has larger capacity of Cd accumulation in roots which prevents Cd from translocating into stems and leaves; conversely, AC Hime has smaller capacity of Cd accumulation in roots; more Cd is transported into stems and leaves. The different capacity of Cd in roots between Westag 97 and AC Hime causes the different Cd concentration in seeds. Meanwhile, according to the different expression levels of RSTK, ISCP, and H+-ATPase between Westag 97 and AC Hime, RSTK may be involved in transporting Cd into stems and leaves; H+-ATPase may be correlated to the capacity of Cd accumulation in roots; and Cd caused some changes of fundamental life process which leaded to the different expression patterns of ISCP between Westag 97 and
AC Hime
Guiding phosphorus stewardship for multiple ecosystem services
The essential role of phosphorus (P) for agriculture and its impact on water quality has received decades of research attention. However, the benefits of sustainable P use and management for society due to its downstream impacts on multiple ecosystem services are rarely acknowledged. We propose a conceptual framework—the “phosphorus-ecosystem services cascade” (PESC)—to integrate the key ecosystem processes and functions that moderate the relationship between P released to the environment from human actions and ecosystem services at distinct spatial and temporal scales. Indirect pathways in the cascade via soil and aquatic processes link anthropogenic P to biodiversity and multiple services, including recreation, drinking water provision, and fisheries. As anthropogenic P cascades through catchments, it often shifts from a subsidy to a stressor of ecosystem services. Phosphorus stewardship can have emergent ecosystem service co-benefits due to synergies with other societal or management goals (e.g., recycling of livestock manures and organic wastes could impact soil carbon storage). Applying the PESC framework, we identify key research priorities to align P stewardship with the management of multiple ecosystem services, such as incorporating additional services into agri-environmental P indices, assessing how widespread recycling of organic P sources could differentially impact agricultural yields and water quality, and accounting for shifting baselines in P stewardship due to climate change. Ultimately, P impacts depend on site-specific agricultural and biogeophysical contexts, so greater precision in targeting stewardship strategies to specific locations would help to optimize for ecosystem services and to more effectively internalize the downstream costs of farm nutrient management
Carbon-sensitive pedotransfer functions for plant available water
Currently accepted pedotransfer functions show negligible effect of management-induced changes to soil organic carbon (SOC) on plant available water holding capacity (θAWHC), while some studies show the ability to substantially increase θAWHC through management. The Soil Health Institute\u27s North America Project to Evaluate Soil Health Measurements measured water content at field capacity using intact soil cores across 124 long-term research sites that contained increases in SOC as a result of management treatments such as reduced tillage and cover cropping. Pedotransfer functions were created for volumetric water content at field capacity (θFC) and permanent wilting point (θPWP). New pedotransfer functions had predictions of θAWHC that were similarly accurate compared with Saxton and Rawls when tested on samples from the National Soil Characterization database. Further, the new pedotransfer functions showed substantial effects of soil calcareousness and SOC on θAWHC. For an increase in SOC of 10 g kg–1 (1%) in noncalcareous soils, an average increase in θAWHC of 3.0 mm 100 mm–1 soil (0.03 m3 m–3) on average across all soil texture classes was found. This SOC related increase in θAWHC is about double previous estimates. Calcareous soils had an increase in θAWHC of 1.2 mm 100 mm–1 soil associated with a 10 g kg–1 increase in SOC, across all soil texture classes. New equations can aid in quantifying benefits of soil management practices that increase SOC and can be used to model the effect of changes in management on drought resilience
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Linking soil microbial community structure to potential carbon mineralization: A continental scale assessment of reduced tillage
Potential carbon mineralization (Cmin) is a commonly used indicator of soil health, with greater Cmin values interpreted as healthier soil. While Cmin values are typically greater in agricultural soils managed with minimal physical disturbance, the mechanisms driving the increases remain poorly understood. This study assessed bacterial and archaeal community structure and potential microbial drivers of Cmin in soils maintained under various degrees of physical disturbance. Potential carbon mineralization, 16S rRNA sequences, and soil characterization data were collected as part of the North American Project to Evaluate Soil Health Measurements (NAPESHM). Results showed that type of cropping system, intensity of physical disturbance, and soil pH influenced microbial sensitivity to physical disturbance. Furthermore, 28% of amplicon sequence variants (ASVs), which were important in modeling Cmin, were enriched under soils managed with minimal physical disturbance. Sequences identified as enriched under minimal disturbance and important for modeling Cmin, were linked to organisms which could produce extracellular polymeric substances and contained metabolic strategies suited for tolerating environmental stressors. Understanding how physical disturbance shapes microbial communities across climates and inherent soil properties and drives changes in Cmin provides the context necessary to evaluate management impacts on standardized measures of soil microbial activity
Investigation of virus capsid self-assembly kinetics using discrete-event stochastic simulation
Self-assembly systems play crucial roles in a broad range of critical biological processes. Investigation of such systems is impeded by the innate stochastic noise of the systems and current experimental limitations. Understanding of such systems, especially complex virus capsid self-assembly systems, is essential for us to build predictive models of cellular function, find novel treatments for many human diseases and build novel nano-machines. Quantitative modeling of virus capsid self-assembly kinetics provides a valuable adjunct to experimental work in understanding self-assembly by allowing us to perform model-assisted interpretation of assembly systems too complex for detailed experimental dissection and to extrapolate results from in vitro experimental conditions to the cellular environment. However, many such computational methods have difficulty in achieving high efficiency and accuracy at the same time. This thesis develops an efficient computational tool using a local rules model, a stochastic queue-based discrete-event simulation algorithm and the Java language to allow the investigation of virus capsid self-assembly kinetics. The simulation program is then used to study (1) the contribution of oligomer/oligomer binding to capsid assembly kinetics, (2) the scaling effects on virus capsid-like self-assembly, and (3) the parameter space of complex self-assembly