Leaf angle is defined as the inclination between the midrib of the leaf blade and the vertical stem of a plant. This trait has been identified as a key component in the development of high-yielding ...varieties of cereal species, particularly maize, rice, wheat, and sorghum. The effect of leaf angle on light interception efficiency, photosynthetic rate, and yield has been investigated since the 1960s, yet, significant knowledge gaps remain in understanding the genetic control of this complex trait. Recent advances in physiology and modeling have proposed a plant ideotype with varying leaf angles throughout the canopy. In this context, we present historical and recent evidence of: (i) the effect of leaf angle on photosynthetic efficiency and yield; (ii) the hormonal regulation of this trait; (iii) the current knowledge on its quantitative genetic control; and (iv) the opportunity to utilize high-throughput phenotyping methods to characterize leaf angle at multiple canopy levels. We focus on research conducted on grass species of economic importance, with similar plant architecture and growth patterns. Finally, we present the challenges and strategies plant breeders will need to embrace in order to manipulate leaf angle differentially throughout the canopy and develop superior crops for food, feed, and fuel production.
In this paper we provide a review and overview of a series of works generated in our laboratory over the last 5 years. These works have described the development and evolution of a new paradigm for ...exchange bias in polycrystalline thin films with grain sizes in the range 5–15
nm. We have shown that the individual grains in the antiferromagnetic (AF) layer of exchange bias systems contain a single AF domain and reverse over an energy barrier which is grain volume dependent. We show that the AF grains are not coupled to each other and behave independently. Understanding this process and using designed measurement protocols has enabled us to determine unambiguously the blocking temperature distribution of the AF grains, the anisotropy constant (
K
AF) of the AF, understand the AF grain-setting process, and predict its magnetic viscosity. We can explain and predict the grain size and film thickness dependence of the exchange field
H
ex. We have also studied interfacial effects and shown that there are processes at the interface, which can occur independently of the bulk of the AF grains. We have seen these effects via studies of trilayers and also via the field dependence of the setting process which does not affect the blocking. From separate experiments we have shown that the disordered interfacial spins exist as spin clusters analogous to a spin glass. These clusters can order spontaneously at low temperatures or can be ordered by the setting field. We believe it is the degree of order of the interfacial spins that gives rise to the coercivity in exchange bias systems. Based on this new understanding of the behaviour of the bulk of the grains in the antiferromagnet and the interfacial spins we believe that we have now a new paradigm for the phenomenon of exchange bias in sputtered polycrystalline thin films. We emphasize that the phenomenological model does not apply to core–shell particles, epitaxial single-crystal films and large grain polycrystalline films.
Corrosion mechanisms for current heat transfer fluid and storage media used in CSP plants working at temperatures from 300 °C to 600 °C are reviewed in this paper. The studies found in the literature ...show that these mechanisms are influenced by the impurities present in the salt and the relation between Mg(NO3)2, moisture, CO2, perchlorates, and sulphates with the corrosion process. Corrosion mechanisms were identified along with a discussion of the corrosion products and their influence on the corrosion layers formed.
•A comprehensive review of the corrosion mechanisms in commercial nitrate salts has been performed.•The activity of oxide ions drives the oxidation process acting as protective barriers against molten salt corrosion.•Chloride ions and moisture are the main important impurities involved in the corrosión mechanism.
Sorghum (Sorghum bicolor L. Moench) is a C₄ species sensitive to the cold spring conditions that occur at northern latitudes, especially when coupled with excessive light, and that greatly affect the ...photosynthetic rate. The objective of this study was to discover genes/genomic regions that control the capacity to cope with excessive energy under low temperature conditions during the vegetative growth period. A genome-wide association study (GWAS) was conducted for seven photosynthetic gas exchange and chlorophyll fluorescence traits under three consecutive temperature treatments: control (28 °C/24 °C), cold (15 °C/15 °C), and recovery (28 °C/24 °C). Cold stress significantly reduced the rate of photosynthetic CO₂ uptake of sorghum plants, and a total of 143 unique genomic regions were discovered associated with at least one trait in a particular treatment or with derived variables. Ten regions on chromosomes 3, 4, 6, 7, and 8 that harbor multiple significant markers in linkage disequilibrium (LD) were consistently identified in gas exchange and chlorophyll fluorescence traits. Several candidate genes within those intervals have predicted functions related to carotenoids, phytohormones, thioredoxin, components of PSI, and antioxidants. These regions represent the most promising results for future validation and with potential application for the improvement of crop productivity under cold stress.
Recent advances in omics technologies have not been accompanied by equally efficient, cost-effective, and accurate phenotyping methods required to dissect the genetic architecture of complex traits. ...Even though high-throughput phenotyping platforms have been developed for controlled environments, field-based aerial and ground technologies have only been designed and deployed for short-stature crops. Therefore, we developed and tested Phenobot 1.0, an auto-steered and self-propelled field-based high-throughput phenotyping platform for tall dense canopy crops, such as sorghum (Sorghum bicolor). Phenobot 1.0 was equipped with laterally positioned and vertically stacked stereo RGB cameras. Images collected from 307 diverse sorghum lines were reconstructed in 3D for feature extraction. User interfaces were developed, and multiple algorithms were evaluated for their accuracy in estimating plant height and stem diameter. Tested feature extraction methods included the following: (1) User-interactive Individual Plant Height Extraction (UsIn-PHe) based on dense stereo three-dimensional reconstruction; (2) Automatic Hedge-based Plant Height Extraction (Auto-PHe) based on dense stereo 3D reconstruction; (3) User-interactive Dense Stereo Matching Stem Diameter Extraction; and (4) User-interactive Image Patch Stereo Matching Stem Diameter Extraction (IPaS-Di). Comparative genome-wide association analysis and ground-truth validation demonstrated that both UsIn-PHe and Auto-PHe were accurate methods to estimate plant height, while Auto-PHe had the additional advantage of being a completely automated process. For stem diameter, IPaS-Di generated the most accurate estimates of this biomass-related architectural trait. In summary, our technology was proven robust to obtain ground-based high-throughput plant architecture parameters of sorghum, a tall and densely planted crop species.
The extracellular matrix (ECM) is pivotal in modulating tumor progression. Besides chemically stimulating tumor cells, it also offers physical support that orchestrates the sequence of events in the ...metastatic cascade upon dynamically modulating cell mechanosensation. Understanding this translation between matrix biophysical cues and intracellular signaling has led to rapid growth in the interdisciplinary field of cancer mechanobiology in the last decade. Substantial efforts have been made to develop novel in vitro tumor mimicking platforms to visualize and quantify the mechanical forces within the tissue that dictate tumor cell invasion and metastatic growth. This review highlights recent findings on tumor matrix biophysical cues such as fibrillar arrangement, crosslinking density, confinement, rigidity, topography, and non-linear mechanics and their implications on tumor cell behavior. We also emphasize how perturbations in these cues alter cellular mechanisms of mechanotransduction, consequently enhancing malignancy. Finally, we elucidate engineering techniques to individually emulate the mechanical properties of tumors that could help serve as toolkits for developing and testing ECM-targeted therapeutics on novel bioengineered tumor platforms.
Disrupted ECM mechanics is a driving force for transitioning incipient cells to life-threatening malignant variants. Understanding these ECM changes can be crucial as they may aid in developing several efficacious drugs that not only focus on inducing cytotoxic effects but also target specific matrix mechanical cues that support and enhance tumor invasiveness. Designing and implementing an optimal tumor mimic can allow us to predictively map biophysical cue-modulated cell behaviors and facilitate the design of improved lab-grown tumor models with accurately controlled structural features. This review focuses on the abnormal changes within the ECM during tumorigenesis and its implications on tumor cell-matrix mechanoreciprocity. Additionally, it accentuates engineering approaches to produce ECM features of varying levels of complexity which is critical for improving the efficiency of current engineered tumor tissue models.
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The Society of Thoracic Surgeons (STS)-Interagency Registry for Mechanically Assisted Circulatory Support (Intermacs) 2020 Annual Report reviews outcomes on 25,551 patients undergoing primary ...isolated continuous-flow left ventricular assist device (LVAD) implantation between 2010 and 2019. In 2019, 3198 primary LVADs were implanted, which is the highest annual volume in Intermacs history. Compared with the previous era (2010-2014), patients who received an LVAD in the most recent era (2015-2019) were more likely to be African American (26.8% vs 22.9%, P < .0001) and more likely to be bridged to durable LVAD with temporary mechanical support devices (36.8% vs 26.0%, P < .0001). In 2019, 50% of patients were INTERMACS Profile 1 or 2 before durable LVAD, and 73% received an LVAD as destination therapy. Magnetic levitation technology has become the predominant design, accounting for 77% of devices in 2019. The 1- and 2-year survival in the most recent era has improved compared with 2010 to 2014 (82.3% and 73.1% vs 80.5% and 69.1%, respectively; P < .0001). Major bleeding and infection continue to be the leading adverse events. Incident stroke has declined in the current era to 12.7% at 1 year. STS-Intermacs research publications are highlighted, and the new quality initiatives are introduced.
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Primary biliary cholangitis (PBC) is a chronic cholestatic liver disease associated with autoimmune phenomena targeting intrahepatic bile duct cells (cholangiocytes). Although its etiopathogenesis ...remains obscure, development of antimitochondrial autoantibodies against pyruvate dehydrogenase complex E2 is a common feature. MicroRNA (miR) dysregulation occurs in liver and immune cells of PBC patients, but its functional relevance is largely unknown. We previously reported that miR‐506 is overexpressed in PBC cholangiocytes and directly targets both Cl–/
HCO3− anion exchanger 2 and type III inositol 1,4,5‐trisphosphate receptor, leading to cholestasis. Here, the regulation of miR‐506 gene expression and its role in cholangiocyte pathophysiology and immune activation was studied. Several proinflammatory cytokines overexpressed in PBC livers (such as interleukin‐8 IL8, IL12, IL17, IL18, and tumor necrosis factor alpha) stimulated miR‐506 promoter activity in human cholangiocytes, as revealed by luciferase reporter assays. Experimental overexpression of miR‐506 in cholangiocytes dysregulated the cell proteomic profile (by mass spectrometry), affecting proteins involved in different biological processes including mitochondrial metabolism. In cholangiocytes, miR‐506 (1) induced dedifferentiation with down‐regulation of biliary and epithelial markers together with up‐regulation of mesenchymal, proinflammatory, and profibrotic markers; (2) impaired cell proliferation and adhesion; (3) increased oxidative and endoplasmic reticulum stress; (4) caused DNA damage; and (5) sensitized to caspase‐3‐dependent apoptosis induced by cytotoxic bile acids. These events were also associated with impaired energy metabolism in mitochondria (proton leak and less adenosine triphosphate production) and pyruvate dehydrogenase complex E2 overexpression. Coculture of miR‐506 overexpressing cholangiocytes with PBC immunocytes induced activation and proliferation of PBC immunocytes. Conclusion: Different proinflammatory cytokines enhance the expression of miR‐506 in biliary epithelial cells; miR‐506 induces PBC‐like features in cholangiocytes and promotes immune activation, representing a potential therapeutic target for PBC patients. (Hepatology 2018;67:1420‐1440)
Biofilms are often more resistant to toxic chemicals such as heavy metals and antimicrobial agents than planktonic cells. Nanosilver has a broad range of applications with strong antimicrobial ...activity. However, biofilm susceptibility to nanosilver toxicity is not well understood. We studied the bacterial activity in planktonic or biofilm cultures after nanosilver exposure using oxygen quenching fluorescence-based microrespirometry. We also determined the aggregation behavior and the spatial distribution of nanosilver having red fluorescence in biofilms of
Escherichia coli expressing green fluorescent protein. At the same bacterial concentrations (3 × 10
8 CFU/mL), biofilms were about four times more resistant to nanosilver inhibition than planktonic cells. The minimum bactericidal concentrations (MBCs) of nanosilver (size from 15 to 21 nm), defined as the lowest concentration that kills at least 99.9% of a planktonic or biofilm bacterial population, were 38 and 10 mg/L Ag, respectively. For comparison, silver ions were more toxic to
E. coli than nanosilver with MBCs of 2.4 and 1.2 mg/L Ag for planktonic and biofilm cultures, respectively. Nanosilver was aggregated in the presence of planktonic or biofilm-forming cells resulting in an increase of average particle size by a factor of 15 and 40, respectively. The nanosilver particles were able to penetrate to approximately 40 μm in a thick biofilm after 1-h exposure. These findings suggested that biofilm resistance to nanosilver could be at least partially due to nanoparticle aggregation and retarded silver ion/particle diffusion.
Cancer-associated fibroblasts (CAF) have been suggested to originate from mesenchymal stromal cells (MSC), but their relationship with MSCs is not clear. Here, we have isolated from primary human ...neuroblastoma tumors a population of αFAP- and FSP-1-expressing CAFs that share phenotypic and functional characteristics with bone marrow-derived MSCs (BM-MSC). Analysis of human neuroblastoma tumors also confirmed the presence of αFAP- and FSP-1-positive cells in the tumor stroma, and their presence correlated with that of M2 tumor-associated macrophages. These cells (designated CAF-MSCs) enhanced
neuroblastoma cell proliferation, survival, and resistance to chemotherapy and stimulated neuroblastoma tumor engraftment and growth in immunodeficient mice, indicating an effect independent of the immune system. The protumorigenic activity of MSCs
and in xenografted mice was dependent on the coactivation of JAK2/STAT3 and MEK/ERK1/2 in neuroblastoma cells. In a mouse model of orthotopically implanted neuroblastoma cells, inhibition of JAK2/STAT3 and MEK/ERK/1/2 by ruxolitinib and trametinib potentiated tumor response to etoposide and increased overall survival. These data point to a new type of protumorigenic CAF in the tumor microenvironment of neuroblastoma and to STAT3 and ERK1/2 as mediators of their activity.
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