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At least 19 records

Spatial modeling algorithms for reactions and transport in biological cells

Biological cells rely on precise spatiotemporal coordination of biochemical reactions to control their functions. Such cell signaling networks have been a common focus for mathematical models, but they remain challenging to simulate, particularly in realistic cell geometries. Here we present Spatial Modeling Algorithms for Reactions and Transport (SMART), a software package that takes in high-level user specifications about cell signaling networks and then assembles and solves the associated mathematical systems. SMART uses state-of-the-art finite element analysis, via the FEniCS Project software, to efficiently and accurately resolve cell signaling events over discretized cellular and subcellular geometries. We demonstrate its application to several different biological systems, including yes-associated protein (YAP)/PDZ-binding motif (TAZ) mechanotransduction, calcium signaling in neurons and cardiomyocytes, and ATP generation in mitochondria. Throughout, we utilize experimentally derived realistic cellular geometries represented by well-conditioned tetrahedral meshes. These scenarios demonstrate the applicability, flexibility, accuracy and efficiency of SMART across a range of temporal and spatial scales.

59 BASIC BIOLOGICAL SCIENCES↗

Design patterns of biological cells

Design patterns are generalized solutions to frequently recurring problems. They were initially developed by architects and computer scientists to create a higher level of abstraction for their designs. Here, we extend these concepts to cell biology to lend a new perspective on the evolved designs of cells' underlying reaction networks. We present a catalog of 21 design patterns divided into three categories: creational patterns describe processes that build the cell, structural patterns describe the layouts of reaction networks, and behavioral patterns describe reaction network function. Applying this pattern language to the E. coli central metabolic reaction network, the yeast pheromone response signaling network, and other examples lends new insights into these systems.

59 BASIC BIOLOGICAL SCIENCES↗

Cell Biology: A Love Affair

Cell biology, represented by its society, the American Society for Cell Biology (ASCB), remains vibrant precisely because it welcomes the young. The future belongs to the students and fellows. Indeed, as ASCB president in the 1990s, together with one of my fellows at the time, Sophie Lelievre, we organized one of the first “postdoctoral societies” in the United States at Lawrence Berkeley National Laboratory and then took the idea to the ASCB to form what now has become a standing and productive committee. The ASCB and its members know that fundamental cell biology remains relevant today, because the cell in context is both the “dancer and the dance.”

59 BASIC BIOLOGICAL SCIENCES↗

Mesangial cell biology

Mesangial cells originate from the metanephric mesenchyme and maintain structural integrity of the glomerular microvascular bed and mesangial matrix homeostasis. In response to metabolic, immunologic or hemodynamic injury, these cells undergo apoptosis or acquire an activated phenotype and undergo hypertrophy, proliferation with excessive production of matrix proteins, growth factors, chemokines and cytokines. These soluble factors exert autocrine and paracrine effects on the cells or on other glomerular cells, respectively. MCs are primary targets of immune-mediated glomerular diseases such as IGA nephropathy or metabolic diseases such as diabetes. MCs may also respond to injury that primarily involves podocytes and endothelial cells or to structural and genetic abnormalities of the glomerular basement membrane. Signal transduction and oxidant stress pathways are activated in MCs and likely represent integrated input from multiple mediators. Such responses are convenient targets for therapeutic intervention. Studies in cultured MCs should be supplemented with in vivo studies as well as examination of freshly isolated cells from normal and diseases glomeruli. In addition to ex vivo morphologic studies in kidney cortex, cells should be studied in their natural environment, isolated glomeruli or even tissue slices. Identification of a specific marker of MCs should help genetic manipulation as well as selective therapeutic targeting of these cells. Identification of biological responses of MCs that are not mediated by the renin–angiotensin system should help development of novel and effective therapeutic strategies to treat diseases characterized by MC pathology.

60 APPLIED LIFE SCIENCES↗

Cryogenic electron tomography by the numbers: Charting underexplored lineages in structural cell biology

Imaging cells and their interactions across the whole biosphere with molecular-scale resolution is key for understanding structure–function relations. Cryogenic electron tomography (cryo-ET) is a powerful method for obtaining this critical information. However, cryo-ET studies are challenging and often limited to a small number of cell types per study. Here, we collate cryo-ET data from hundreds of cells and tissues across the biosphere to i) identify emerging methodological trends, ii) pinpoint strategies to reduce imaging time and costs, iii) quantitatively compare methods for cell freezing and sectioning, and iv) census cryo-ET species coverage across all domains of life. Comparing the fraction of cellular material within a single lamella across all domains of life reveals an order of magnitude difference between eukaryotes (1%) compared to bacteria (9%) and archaea (14%). We calculate the fraction of cellular material which can be imaged using distinct sectioning methods on multicellular communities and tissues—identifying serial lift-out as a powerful approach for obtaining more complete cellular depictions. Finally, we show that the biodiversity of current cryo-ET studies is 2 to 3 orders of magnitude lower than in sequence libraries and 4 to 5 lower than the total predicted on Earth. Our analyses reveal major evolutionary lineages which remain critically understudied and highlight where future cryo-ET research would be most impactful.

HPF↗

A revisited concept: Contact inhibition of growth. From cell biology to malignancy

In cell biology, contact inhibition refers to two different but closely related phenomena, contact inhibition of locomotion and contact inhibition of proliferation, exhibited by fibroblasts when in contact with one another. Normal fibroblasts migrate across the surface of a culture dish until they make contact with a neighboring cell. Further cell migration is then inhibited, and normal cells adhere to each other, forming an orderly array of cells on the culture dish surface. Tumor cells, in contrast, continue moving after contact with their neighbors, migrating over adjacent cells, and growing in disordered, multilayered patterns. Not only the movement but also the proliferation of many normal cells is inhibited by cell-cell contact, and cancer cells are characteristically insensitive to such contact inhibition. - Highlights: • Contact inhibition refers to contact inhibition of locomotion and of proliferation. • Normal fibroblasts migrate across a culture dish until they make contact with a neighboring cell. • Tumor cells, in contrast, continue moving after contact with their neighbors.

60 APPLIED LIFE SCIENCES↗

A rich and bountiful harvest: Key discoveries in plant cell biology

Abstract The field of plant cell biology has a rich history of discovery, going back to Robert Hooke’s discovery of cells themselves. The development of microscopes and preparation techniques has allowed for the visualization of subcellular structures, and the use of protein biochemistry, genetics, and molecular biology has enabled the identification of proteins and mechanisms that regulate key cellular processes. In this review, seven senior plant cell biologists reflect on the development of this research field in the past decades, including the foundational contributions that their teams have made to our rich, current insights into cell biology. Topics covered include signaling and cell morphogenesis, membrane trafficking, cytokinesis, cytoskeletal regulation, and cell wall biology. In addition, these scientists illustrate the pathways to discovery in this exciting research field.

59 BASIC BIOLOGICAL SCIENCES↗

Plant Cell Biology International Meeting 2022

There is a strong need to develop the knowledge base that will enable the rational design of improved crop species for sustainable agriculture and biomass production. To attain this goal, researchers must learn how plant cells integrate metabolism and cellular dynamics during growth and in response to environmental challenges. Meeting these goals require data sharing and the development and training of faculty, post-doctoral fellows, graduate and undergraduate students in state-of-the-art quantitative integrative cell biology methods. The inaugural Plant Cell Biology International (PCBI) meeting capitalized on the interaction between two well-established plant cell biology communities across the Atlantic, the Midwest Plant Cell Dynamics (PCD) and the European Network for Plant Endomembrane Research (ENPER) and provided a framework to meet these goals. The conference took place in person successfully during August 1-5th 2022 in Crete, Greece. The conference offered opportunities for undergraduate and graduate students, postdocs, young investigators across the globe to present their results and interact across different disciplines. The conference provided an open and inclusive forum for oral presentations that allowed all labs to share research results. It was attended over 80 % by students, postdocs and young investigators. Workshops on best practices for image acquisition and processing pipelines, publication guidelines by scientific journal editors, professional development and well-being benefited the participants at large. Overall, this was the inaugural joint Plant Cell Biology International conference that for the first time officially brought together plant cell biologists to discuss opportunities and challenges in the field to gain a mechanistic understanding of complex biological processes and advance sustainable agriculture. Due to its success, it was rescheduled for 2025 in Crete, to continue strengthening the plant cell biology community and exchanging knowledge and expertise across the globe.

59 BASIC BIOLOGICAL SCIENCES↗

Efficient Simulation of Nested Hollow Sphere Intersections: for Dynamically Nested Compartmental Models in Cell Biology

In the particle-based simulation of cell-biological systems in continuous space, a key performance bottleneck is the computation of all possible intersections between particles. These typically rely for collision detection on solid sphere approaches. The behavior of cell biological systems is influenced by dynamic hierarchical nesting, such as the forming of, the transport within, and the merging of vesicles. Existing collision detection algorithms are found not to be designed for these types of spatial cell-biological models, because nearly all existing high performance parallel algorithms are focusing on solid sphere interactions. The known algorithms for solid sphere intersections return more intersections than actually occur with nested hollow spheres. Here we define a new problem of computing the intersections among arbitrarily nested hollow spheres of possibly different sizes, thicknesses, positions, and nesting levels. We describe a new algorithm designed to solve this nested hollow sphere intersection problem and implement it for parallel execution on graphical processing units (GPUs). We present first results about the runtime performance and scaling to hundreds of thousands of spheres, and compare the performance with that from a leading solid object intersection package also running on GPUs.

Koester, Till↗

Prognostic Cell Biological Markers in Cervical Cancer Patients Primarily Treated With (Chemo)radiation: A Systematic Review

The aim of this study was to systematically review the prognostic and predictive significance of cell biological markers in cervical cancer patients primarily treated with (chemo)radiation. A PubMed, Embase, and Cochrane literature search was performed. Studies describing a relation between a cell biological marker and survival in {>=}50 cervical cancer patients primarily treated with (chemo)radiation were selected. Study quality was assessed, and studies with a quality score of 4 or lower were excluded. Cell biological markers were clustered on biological function, and the prognostic and predictive significance of these markers was described. In total, 42 studies concerning 82 cell biological markers were included in this systematic review. In addition to cyclooxygenase-2 (COX-2) and serum squamous cell carcinoma antigen (SCC-ag) levels, markers associated with poor prognosis were involved in epidermal growth factor receptor (EGFR) signaling (EGFR and C-erbB-2) and in angiogenesis and hypoxia (carbonic anhydrase 9 and hypoxia-inducible factor-1{alpha}). Epidermal growth factor receptor and C-erbB-2 were also associated with poor response to (chemo)radiation. In conclusion, EGFR signaling is associated with poor prognosis and response to therapy in cervical cancer patients primarily treated with (chemo)radiation, whereas markers involved in angiogenesis and hypoxia, COX-2, and serum SCC-ag levels are associated with a poor prognosis. Therefore, targeting these pathways in combination with chemoradiation may improve survival in advanced-stage cervical cancer patients.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

The Archaeal Proteome Project advances knowledge about archaeal cell biology through comprehensive proteomics

Abstract While many aspects of archaeal cell biology remain relatively unexplored, systems biology approaches like mass spectrometry (MS) based proteomics offer an opportunity for rapid advances. Unfortunately, the enormous amount of MS data generated often remains incompletely analyzed due to a lack of sophisticated bioinformatic tools and field-specific biological expertise for data interpretation. Here we present the initiation of the Archaeal Proteome Project (ArcPP), a community-based effort to comprehensively analyze archaeal proteomes. Starting with the model archaeon Haloferax volcanii , we reanalyze MS datasets from various strains and culture conditions. Optimized peptide spectrum matching, with strict control of false discovery rates, facilitates identifying > 72% of the reference proteome, with a median protein sequence coverage of 51%. These analyses, together with expert knowledge in diverse aspects of cell biology, provide meaningful insights into processes such as N-terminal protein maturation, N -glycosylation, and metabolism. Altogether, ArcPP serves as an invaluable blueprint for comprehensive prokaryotic proteomics.

59 BASIC BIOLOGICAL SCIENCES↗

Method and apparatus for sustaining viability of biological cells on a substrate

A method for the transient transformation of a living biological cell having an intact cell membrane defining an intracellular domain, and an apparatus for the transient transformation of biological cells. The method and apparatus include introducing a compartmentalized extracellular component fixedly attached to a cellular penetrant structure to the intracellular domain of the cell, wherein the cell is fixed in a predetermined location and wherein the component is expressed within in the cell while being retained within the compartment and wherein the compartment restricts the mobility and interactions of the component within the cell and prevents transference of the component to the cell.

59 BASIC BIOLOGICAL SCIENCES↗

Method and apparatus for sustaining viability of biological cells on a substrate

A method for the transient transformation of a living biological cell having an intact cell membrane defining an intracellular domain, and an apparatus for the transient transformation of biological cells. The method and apparatus include introducing a compartmentalized extracellular component fixedly attached to a cellular penetrant structure to the intracellular domain of the cell, wherein the cell is fixed in a predetermined location and wherein the component is expressed within in the cell while being retained within the compartment and wherein the compartment restricts the mobility and interactions of the component within the cell and prevents transference of the component to the cell.

60 APPLIED LIFE SCIENCES↗

Simulation of CNT-AFM tip based on finite element analysis for targeted probe of the biological cell

Carbon nanotubes (CNTs) are potentially ideal tips for atomic force microscopy (AFM) due to the robust mechanical properties, nano scale diameter and also their ability to be functionalized by chemical and biological components at the tip ends. This contribution develops the idea of using CNTs as an AFM tip in computational analysis of the biological cell’s. Finite element analysis employed for each section and displacement of the nodes located in the contact area was monitored by using an output database (ODB). This reliable integration of CNT-AFM tip process provides a new class of high performance nanoprobes for single biological cell analysis.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

Shape-Preserved Transformation of Biological Cells into Synthetic Hydrogel Microparticles

The synthesis of materials that can mimic the mechanical, and ultimately functional, properties of biological cells can broadly impact the development of biomimetic materials, as well as engineered tissues and therapeutics. Yet, it is challenging to synthesize, for example, microparticles that share both the anisotropic shapes and the elastic properties of living cells. Here in paper, a cell-directed route to replicate cellular structures into synthetic hydrogels such as polyethylene glycol (PEG) is described. First, the internal and external surfaces of chemically fixed cells are replicated in a conformal layer of silica using a sol–gel process. The template is subsequently removed to render shape-preserved, mesoporous silica replicas. Infiltration and cross-linking of PEG precursors and dissolution of the silica result in a soft hydrogel replica of the cellular template as demonstrated using erythrocytes, HeLa, and neuronal cultured cells. The elastic modulus can be tuned over an order of magnitude (≈10–100 kPa) though with a high degree of variability. Furthermore, synthesis without removing the biotemplate results in stimuli-responsive particles that swell/deswell in response to environmental cues. Overall, this work provides a foundation to develop soft particles with nearly limitless architectural complexity derived from dynamic biological templates.

59 BASIC BIOLOGICAL SCIENCES↗

Quantification of nanoscale density fluctuations using electron microscopy: Light-localization properties of biological cells

We report a study of the nanoscale mass-density fluctuations of heterogeneous optical dielectric media, including nanomaterials and biological cells, by quantifying their nanoscale light-localization properties. Transmission electron microscope images of the media are used to construct corresponding effective disordered optical lattices. Light-localization properties are studied by the statistical analysis of the inverse participation ratio (IPR) of the localized eigenfunctions of these optical lattices at the nanoscale. We validated IPR analysis using nanomaterials as models of disordered systems fabricated from dielectric nanoparticles. As an example, we then applied such analysis to distinguish between cells with different degrees of aggressive malignancy.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗