Measurement and modeling of volume scattering functions for phytoplankton from Norwegian coastal waters

The volume scattering function (VSF) describes the angular distribution of scattered light, and the VSF of phytoplankton is one of the most important inherent optical properties of oceanic water. Despite its importance, relatively few measurements of the VSF have been carried out in aquatic environments, and we present here data and analyses of measured VSFs at 442, 490, and 550 nm for 15 representative phytoplankton species from Norwegian coastal waters. In addition, the analytic scattering phase functions Henyey-Greenstein (HG) and Fournier-Forand, as well as Mie theory, were fitted and compared to the measured VSFs. The measured VSFs for all the species were strongly, but unequally forward peaked with HG-fitted asymmetry factors in the range 0.897–0.988. The VSF of Synechococcus sp., Phaeodactylum tricornutum, and Emiliania huxleyi (naked) had shoulders in the forward direction, whereas the VSF of the cylindrically shaped Chaetoceros calcitrans and Chaetoceros wighamii had minima in the backward direction. Results from this work indicate that internal structures influence the angular and spectral shape of the VSF more significantly than the morphology and size of the phytoplankton cells

Intrinsic Differences in Spatiotemporal Organization and Stromal Cell Interactions Between Isogenic Lung Cancer Cells of Epithelial and Mesenchymal Phenotypes Revealed by High-Dimensional Single-Cell Analysis of Heterotypic 3D Spheroid Models

The lack of inadequate preclinical models remains a limitation for cancer drug development and is a primary contributor to anti-cancer drug failures in clinical trials. Heterotypic multicellular spheroids are three-dimensional (3D) spherical structures generated by self-assembly from aggregates of two or more cell types. Compared to traditional monolayer cell culture models, the organization of cells into a 3D tissue-like structure favors relevant physiological conditions with chemical and physical gradients as well as cell-cell and cell-extracellular matrix (ECM) interactions that recapitulate many of the hallmarks of cancer in situ. Epidermal growth factor receptor (EGFR) mutations are prevalent in non-small cell lung cancer (NSCLC), yet various mechanisms of acquired resistance, including epithelial-to-mesenchymal transition (EMT), limit the clinical benefit of EGFR tyrosine kinase inhibitors (EGFRi). Improved preclinical models that incorporate the complexity induced by epithelial-to-mesenchymal plasticity (EMP) are urgently needed to advance new therapeutics for clinical NSCLC management. This study was designed to provide a thorough characterization of multicellular spheroids of isogenic cancer cells of various phenotypes and demonstrate proof-of-principle for the applicability of the presented spheroid model to evaluate the impact of cancer cell phenotype in drug screening experiments through high-dimensional and spatially resolved imaging mass cytometry (IMC) analyses. First, we developed and characterized 3D homotypic and heterotypic spheroid models comprising EGFRi-sensitive or EGFRi-resistant NSCLC cells. We observed that the degree of EMT correlated with the spheroid generation efficiency in monocultures. In-depth characterization of the multicellular heterotypic spheroids using immunohistochemistry and high-dimensional single-cell analyses by IMC revealed intrinsic differences between epithelial and mesenchymal-like cancer cells with respect to self-sorting, spatiotemporal organization, and stromal cell interactions when co-cultured with fibroblasts. While the carcinoma cells harboring an epithelial phenotype self-organized into a barrier sheet surrounding the fibroblasts, mesenchymal-like carcinoma cells localized to the central hypoxic and collagen-rich areas of the compact heterotypic spheroids. Further, deep-learning-based single-cell segmentation of IMC images and application of dimensionality reduction algorithms allowed a detailed visualization and multiparametric analysis of marker expression across the different cell subsets. We observed a high level of heterogeneity in the expression of EMT markers in both the carcinoma cell populations and the fibroblasts. Our study supports further application of these models in pre-clinical drug testing combined with complementary high-dimensional single-cell analyses, which in turn can advance our understanding of the impact of cancer-stroma interactions and epithelial phenotypic plasticity on innate and acquired therapy resistance in NSCLC.publishedVersio

UV transmission in Norwegian marine waters: controlling factors and possible effects on primary production and vertical distribution of phytoplankton

We investigated the ultraviolet radiation (UVR) transmission properties of Norwegian oceanic, coastal and fjord waters, and how they influence the primary production and vertical distribution of phytoplankton. Values of the 1% UVR attenuation depth and diffuse attenuation coefficients (Kd) in the Greenland and Norwegian Seas (GNS), in the coastal waters of south-western Norway (SWN) and in the Samnanger fjord (SAF) are presented. Maximum penetration of UVR in the GNS was confirmed by Kd(320) = 0.25 m–1, and mimimum penetration in the SAF, by Kd(320) = 9 m–1. In the GNS, Kd and chlorophyll a (chl a) were closely correlated, while coloured dissolved organic matter (CDOM) was the main contributor to ultraviolet (UV) attenuation in the SAF. Also, in SWN waters, CDOM was more important than chl a for UV attenuation, but less important than in SAF waters. In GNS and SAF waters the average vertical distribution of chl a had its maximum in the upper 10 and 7.5 m of the water column, respectively, while in SWN waters it had its maximum at 20 m. The depths with the highest photosynthetic rates per unit volume decreased successively from the oceanic waters of the GNS via the coastal waters of the SWN to the fjord waters of the SAF. Under similar PAR intensities, however, the water column photosynthetic efficiency (integrated carbon assimilation/chl a ratio) was highest in SWN waters. Maximum and mean percentage potential for inhibition of the estimated (from PAR and UV) primary production due to UVR at a depth of 5 m were 11 and 4.3% in the GNS, 3.2 and 0.9% in the SWN and 0.5 and 0.1% in the SAF. The UVR potential for inhibition was significant down to a depth of 10 m in the GNS, down to a depth of 5 m in the waters of the SWN, while it was seldom found deeper than 3 m in the SAF. These variations could be ascribed to differences in CDOM concentrations and mixed-layer depths. The optical properties of the investigated water masses were found to be highly influenced by the circulation patterns

Principal axes for structural fatigue

Recent advances in the analysis of joint seakeeping processes are applied to the accumulation of spectral fatigue cycles. The methods of cross co-spectral moments and techniques adopted from the determination of principal angles for seakeeping processes are used to determine orientation of the most severe plane for the accumulation of spectral fatigue cycles and the distribution of stress cycles on that plane. The theory presented considers all aspects of the wave loads experienced over the life of the structure and uses linear theory to predict lifetime fatigue using more efficient techniques than equally comprehensive time-domain simulation. Three methods of determining the orientation of the principal plane and their theoretical differences are discussed. Quantitative comparisons are presented in the time, frequency and probability domains to illustrate differences and demonstrate consistency

Intrinsic Differences in Spatiotemporal Organization and Stromal Cell Interactions Between Isogenic Lung Cancer Cells of Epithelial and Mesenchymal Phenotypes Revealed by High-Dimensional Single-Cell Analysis of Heterotypic 3D Spheroid Models

The lack of inadequate preclinical models remains a limitation for cancer drug development and is a primary contributor to anti-cancer drug failures in clinical trials. Heterotypic multicellular spheroids are three-dimensional (3D) spherical structures generated by self-assembly from aggregates of two or more cell types. Compared to traditional monolayer cell culture models, the organization of cells into a 3D tissue-like structure favors relevant physiological conditions with chemical and physical gradients as well as cell-cell and cell-extracellular matrix (ECM) interactions that recapitulate many of the hallmarks of cancer in situ. Epidermal growth factor receptor (EGFR) mutations are prevalent in non-small cell lung cancer (NSCLC), yet various mechanisms of acquired resistance, including epithelial-to-mesenchymal transition (EMT), limit the clinical benefit of EGFR tyrosine kinase inhibitors (EGFRi). Improved preclinical models that incorporate the complexity induced by epithelial-to-mesenchymal plasticity (EMP) are urgently needed to advance new therapeutics for clinical NSCLC management. This study was designed to provide a thorough characterization of multicellular spheroids of isogenic cancer cells of various phenotypes and demonstrate proof-of-principle for the applicability of the presented spheroid model to evaluate the impact of cancer cell phenotype in drug screening experiments through high-dimensional and spatially resolved imaging mass cytometry (IMC) analyses. First, we developed and characterized 3D homotypic and heterotypic spheroid models comprising EGFRi-sensitive or EGFRi-resistant NSCLC cells. We observed that the degree of EMT correlated with the spheroid generation efficiency in monocultures. In-depth characterization of the multicellular heterotypic spheroids using immunohistochemistry and high-dimensional single-cell analyses by IMC revealed intrinsic differences between epithelial and mesenchymal-like cancer cells with respect to self-sorting, spatiotemporal organization, and stromal cell interactions when co-cultured with fibroblasts. While the carcinoma cells harboring an epithelial phenotype self-organized into a barrier sheet surrounding the fibroblasts, mesenchymal-like carcinoma cells localized to the central hypoxic and collagen-rich areas of the compact heterotypic spheroids. Further, deep-learning-based single-cell segmentation of IMC images and application of dimensionality reduction algorithms allowed a detailed visualization and multiparametric analysis of marker expression across the different cell subsets. We observed a high level of heterogeneity in the expression of EMT markers in both the carcinoma cell populations and the fibroblasts. Our study supports further application of these models in pre-clinical drug testing combined with complementary high-dimensional single-cell analyses, which in turn can advance our understanding of the impact of cancer-stroma interactions and epithelial phenotypic plasticity on innate and acquired therapy resistance in NSCLC