Cell Shape Changes Research Articles

A Hands-on Guide to AmoePy - a Python-Based Software Package to Analyze Cell Migration Data.

Amoeboid cell motility is fundamental for a multitude of biological processes such as embryogenesis, immune responses, wound healing, and cancer metastasis. It is characterized by specific cell shape changes: the extension and retraction of membrane protrusions, known as pseudopodia. A common approach to investigate the mechanisms underlying this type of cell motility is to study phenotypic differences in the locomotion of mutant cell lines. To characterize such differences, methods are required to quantify the contour dynamics of migrating cells. AmoePy is a Python-based software package that provides tools for cell segmentation, contour detection as well as analyzing and simulating contour dynamics. First, a digital representation of the cell contour as a chain of nodes is extracted from each frame of a time-lapse microscopy recording of a moving cell. Then, the dynamics of these nodes-referred to as virtual markers-are tracked as the cell contour evolves over time. From these data, various quantities can be calculated that characterize the contour dynamics, such as the displacement of the virtual markers or the local stretching rate of the marker chain. Their dynamics is typically visualized in space-time plots, the so-called kymographs, where the temporal evolution is displayed for the different locations along the cell contour. Using AmoePy, you can straightforwardly create kymograph plots and videos from stacks of experimental bright-field or fluorescent images of motile cells. A hands-on guide on how to install and use AmoePy is provided in this chapter.

The alveolus: Our current knowledge of how the gas exchange unit of the lung is constructed and repaired.

The mammalian lung completes its last step of development, alveologenesis, to generate sufficient surface area for gas exchange. In this process, multiple cell types that include alveolar epithelial cells, endothelial cells, and fibroblasts undergo coordinated cell proliferation, cell migration and/or contraction, cell shape changes, and cell-cell and cell-matrix interactions to produce the gas exchange unit: the alveolus. Full functioning of alveoli also involves immune cells and the lymphatic and autonomic nervous system. With the advent of lineage tracing, conditional gene inactivation, transcriptome analysis, live imaging, and lung organoids, our molecular understanding of alveologenesis has advanced significantly. In this review, we summarize the current knowledge of the constituents of the alveolus and the molecular pathways that control alveolar formation. We also discuss how insight into alveolar formation may inform us of alveolar repair/regeneration mechanisms following lung injury and the pathogenic processes that lead to loss of alveoli or tissue fibrosis.

The intricate link between membrane lipid structure and composition and membrane structural properties in bacterial membranes.

It is now evident that the cell manipulates lipid composition to regulate different processes such as membrane protein insertion, assembly and function. Moreover, changes in membrane structure and properties, lipid homeostasis during growth and differentiation with associated changes in cell size and shape, and responses to external stress have been related to drug resistance across mammalian species and a range of microorganisms. While it is well known that the biomembrane is a fluid self-assembled nanostructure, the link between the lipid components and the structural properties of the lipid bilayer are not well understood. This perspective aims to address this topic with a view to a more detailed understanding of the factors that regulate bilayer structure and flexibility. We describe a selection of recent studies that address the dynamic nature of bacterial lipid diversity and membrane properties in response to stress conditions. This emerging area has important implications for a broad range of cellular processes and may open new avenues of drug design for selective cell targeting.

Cofilin-mediated actin filament network flexibility facilitates 2D to 3D actomyosin shape change

The organization of actin filaments (F-actin) into crosslinked networks determines the transmission of mechanical stresses within the cytoskeleton and subsequent changes in cell and tissue shape. Principally mediated by proteins such as α-actinin, F-actin crosslinking increases both network connectivity and rigidity, thereby facilitating stress transmission at low crosslinking yet attenuating transmission at high crosslinker concentration. Here, we engineer a two-dimensional model of the actomyosin cytoskeleton, in which myosin-induced mechanical stresses are controlled by light. We alter the extent of F-actin crosslinking by the introduction of oligomerized cofilin. At pH 6.5, F-actin severing by cofilin is weak, but cofilin bundles and crosslinks filaments. Given its effect of lowering the F-actin bending stiffness, cofilin- crosslinked networks are significantly more flexible and softer in bending than networks crosslinked by α-actinin. Thus, upon local activation of myosin-induced contractile stress, the network bends out-of-plane in contrast to the in-plane compression as observed with networks crosslinked by α-actinin. Here, we demonstrate that local effects on filament mechanics by cofilin introduces novel large-scale network material properties that enable the sculpting of complex shapes in the cell cytoskeleton.

Mechanical control of neural plate folding by apical domain alteration

Vertebrate neural tube closure is associated with complex changes in cell shape and behavior, however, the relative contribution of these processes to tissue folding is not well understood. At the onset of Xenopus neural tube folding, we observed alternation of apically constricted and apically expanded cells. This apical domain heterogeneity was accompanied by biased cell orientation along the anteroposterior axis, especially at neural plate hinges, and required planar cell polarity signaling. Vertex models suggested that dispersed isotropically constricting cells can cause the elongation of adjacent cells. Consistently, in ectoderm, cell-autonomous apical constriction was accompanied by neighbor expansion. Thus, a subset of isotropically constricting cells may initiate neural plate bending, whereas a ‘tug-of-war’ contest between the force-generating and responding cells reduces its shrinking along the body axis. This mechanism is an alternative to anisotropic shrinking of cell junctions that are perpendicular to the body axis. We propose that apical domain changes reflect planar polarity-dependent mechanical forces operating during neural folding.

α-Gal Nanoparticles in CNS Trauma: I. In Vitro Activation of Microglia Towards a Pro-Healing State.

Macrophages and microglia play critical roles after spinal cord injury (SCI), with the pro-healing, anti-inflammatory (M2) subtype being implicated in tissue repair. We hypothesize that promoting this phenotype within the post-injured cord microenvironment may provide beneficial effects for mitigating tissue damage. As a proof of concept, we propose the use of nanoparticles incorporating the carbohydrate antigen, galactose-α-1,3-galactose (α-gal epitope) as an immunomodulator to transition human microglia (HMC3) cells toward a pro-healing state. Quiescent HMC3 cells were acutely exposed to α-gal nanoparticles in the presence of human serum and subsequently characterized for changes in cell shape, expression of anti or pro-inflammatory markers, and secretion of phenotype-specific cytokines. HMC3 cells treated with serum activated α-gal nanoparticles exhibited rapid enlargement and shape change in addition to expressing CD68. Moreover, these activated cells showed increased expression of anti-inflammatory markers like Arginase-1 and CD206 without increasing production of pro-inflammatory cytokines TNF-α or IL-6. This study is the first to show that resting human microglia exposed to a complex of α-gal nanoparticles and anti-Gal (from human serum) can be activated and polarized toward a putative M2 state. The data suggeststhat α-gal nanoparticles may have therapeutic relevanceto the CNS microenvironment, in both recruiting and polarizing macrophages/microglia at the application site. The immunomodulatory activity of these α-gal nanoparticles post-SCI is further described in the companion work (Part II).

Antioxidant, anti-inflammatory, antimicrobial, and anticancer properties of green broad bean pods (Vicia faba L.)

This study featured broad/fava bean pods as by-products of food production. It assessed the chemical composition of green bean pods (Vicia faba L.) and their methanolic extract.
 The extract was tested in vitro for antioxidant, anti-inflammatory, antimicrobial, and anticancer activities against prostate cancer (Pc3) and liver cancer (HepG2) cells. Broad bean pods proved to be rich in carbohydrates, fiber, protein, potassium, calcium, and magnesium. The extract contained 286 mg GAE/g total phenols and 105 mg QE/g total flavonoids. The antioxidant activity of the methanolic extract was measured by 1,1-diphenyl-2-picryl hydrazyl (DPPH) assay. The highest DPPH scavenging activity belonged to the extract concentrations of 1000 μg/mL (80.5%) and 500 μg/mL (73.7%), whereas the IC50 value was 87.35 μg/mL. The methanolic extract possessed the anti-inflammatory effect as it significantly reduced the hemolysis of red blood cells. The maximal inhibition percentage reached 66.7% at 1000 μg/mL. Regarding the antimicrobial activity, the broad bean pod methanolic extract inhibited Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, as well as Candida albicans. The extract reduced the cell viability of human hepatocarcinoma (HepG2) and prostate cancer (PC3) cells in a concentration-dependent manner. It also caused significant changes in cell shape, compared to the control.
 Therefore, broad beans can be recommended for human consumption together with pods, fresh or cooked, as a potential source of bioactive substances in functional food production.

A palisade-shaped membrane reservoir is required for rapid ring cell inflation in Drechslerella dactyloides

Fusion of individual vesicles carrying membrane-building materials with the plasma membrane (PM) enables gradual cell expansion and shape change. Constricting ring (CR) cells of carnivorous fungi triple in size within 0.1-1 s to capture passing nematodes. Here, we investigated how a carnivorous fungus, Drechslerella dactyloides, executes rapid and irreversible PM expansion during CR inflation. During CR maturation, vesicles carrying membrane-building materials accumulate and fuse, forming a structure named the Palisade-shaped Membrane-building Structure (PMS) around the rumen side of ring cells. After CR inflation, the PMS disappears, with partially inflated cells displaying wavy PM and fully inflated cells exhibiting smooth PM, suggesting that the PMS serves as the reservoir for membrane-building materials to enable rapid and extensive PM expansion. The DdSnc1, a v-SNARE protein, accumulates at the inner side of ring cells and is necessary for PMS formation and CR inflation. This study elucidates the unique cellular mechanisms underpinning rapid CR inflation.

Disturbing cytoskeleton by engineered nanomaterials for enhanced cancer therapeutics.

Cytoskeleton plays a significant role in the shape change, migration, movement, adhesion, cytokinesis, and phagocytosis of tumor cells. In clinical practice, some anti-cancer drugs achieve cytoskeletal therapeutic effects by acting on different cytoskeletal protein components. However, in the absence of cell-specific targeting, unnecessary cytoskeletal recombination in organisms would be disastrous, which would also bring about severe side effects during anticancer process. Nanomedicine have been proven to be superior to some small molecule drugs in cancer treatment due to better stability and targeting, and lower side effects. Therefore, this review summarized the recent developments of various nanomaterials disturbing cytoskeleton for enhanced cancer therapeutics, including carbon, noble metals, metal oxides, black phosphorus, calcium, silicon, polymers, peptides, and metal-organic frameworks, etc. A comprehensive analysis of the characteristics of cytoskeleton therapy as well as the future prospects and challenges towards clinical application were also discussed. We aim to drive on this emerging topic through refreshing perspectives based on our own work and what we have also learnt from others. This review will help researchers quickly understand relevant cytoskeletal therapeutic information to further advance the development of cancer nanomedicine.

The proteolysis of ZP proteins is essential to control cell membrane structure and integrity of developing tracheal tubes in Drosophila.

Membrane expansion integrates multiple forces to mediate precise tube growth and network formation. Defects lead to deformations, as found in diseases such as polycystic kidney diseases, aortic aneurysms, stenosis, and tortuosity. We identified a mechanism of sensing and responding to the membrane-driven expansion of tracheal tubes. The apical membrane is anchored to the apical extracellular matrix (aECM) and causes expansion forces that elongate the tracheal tubes. The aECM provides a mechanical tension that balances the resulting expansion forces, with Dumpy being an elastic molecule that modulates the mechanical stress on the matrix during tracheal tube expansion. We show in Drosophila that the zona pellucida (ZP) domain protein Piopio interacts and cooperates with the ZP protein Dumpy at tracheal cells. To resist shear stresses which arise during tube expansion, Piopio undergoes ectodomain shedding by the Matriptase homolog Notopleural, which releases Piopio-Dumpy-mediated linkages between membranes and extracellular matrix. Failure of this process leads to deformations of the apical membrane, tears the apical matrix, and impairs tubular network function. We also show conserved ectodomain shedding of the human TGFβ type III receptor by Notopleural and the human Matriptase, providing novel findings for in-depth analysis of diseases caused by cell and tube shape changes.

The analysis base study on mechanical double enzyme technique for isolating and culturing primary chondrocytes

The mechanical-double enzyme method was used in the current study to isolate and culture primary chondrocytes from the chicken growth plates. The feasibility and practicability of the approach were determined by using trypan blue staining, toluidine blue staining, PCR, and flow cytometry. The immunofluorescence assay was also used to effectively identify chondrocytes, demonstrating the expression of chondrocyte-specific secreted products (Col-II and Aggrecan). The exterior morphology of chondrocytes was studied at several stages, revealing significant changes in cell shape with each generation. Notably, compared to earlier approaches, the mechanical-double enzyme strategy revealed enhanced cell adhesion and much reduced apoptosis rates. The findings indicate that this novel method has great potential for efficient primary chondrocytes culture, providing important insight into chondrocyte ba research and future applications in cartilage tissue engineering.The following technical points are included in this method:•Isolation and culturing primary chondrocytes by a mechanical-double enzyme approach.•The evaluation of cell adhesion and apoptosis of mechanical double enzyme approach as compared to previous approaches.•The confirmation of chondrocyte-specific secreted products' expression via toluidine blue staining, PCR, and immunofluorescence assays.

Determination of Mitotic Index and Evaluation of Cytogenotoxicity of Oxyfluorfen Using Allium Cepa Root Tip Meristematic Cells

The present study aimed to investigate Oxyfluorfen induced cytogenotoxicity employing Allium cepa meristematic cells as test models. The root length inhibition was determined exposing the meristematic cells to eleven Oxyfluorfen concentrations such as 0.01, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9ppm and 1ppm against controls and the inhibition was statistically (p<0.05) significant at 0.2, 0.3, 0.4, 0.7, 0.8, 0.9 and 1ppm and insignificant for the rest. The root length was drastically reduced at 0.3ppm and complete at 1ppm. The significant change in cell shape and structure was observed at 0.4 & 0.5ppm when compared to 0.01 & 0.1ppm. The mitotic index was calculated considering interphase, prophase, metaphase, anaphase and telophase as cell cycle stages out of one thousand cells. The per cent mitotic index of 0.01, 0.1, 0.2, 0.3, 0.4ppm and 0.5ppm concentrations was found to be 49, 32.8, 29.4, 0, 32.8 and 51.4 respectively and this result significantly correlates with root length inhibition studies. Cell cycle check points will block or delay the progression of mitosis due to pesticide interference with mitotic phase duration, making some phases more frequent than others. Therefore, it is established that Oxyfluorfen is cytogenotoxic to Allium cepa meristematic cells and this technique is very convenient to assess how toxic substances bring abnormality at cell and organelles level.

Human Embryo Live Imaging Reveals Nuclear DNA Shedding During Blastocyst Expansion and Biopsy

ABSTRACT The proportion of babies born from in vitro fertilization (IVF) is rising at an exponential rate, highlighting the importance that we have a comprehensive understanding of human preimplantation development and determinants of embryo quality. The early divisions of the embryo after fertilization but before implantation and resulting mitotic errors have been studied primarily in the mouse embryo; however, thus far we have lacked the technology to characterize these critical steps in humans. Establishing an approach that can bypass genetic manipulation and microinjections of DNA or mRNA into human embryos would allow us to better uncover the processes patterning preimplantation human development. This study aimed to evaluate human blastocyst preimplantation development with noninvasive imaging using membrane permeable fluorescent dyes. First, the dyes SPY650-DNA, which labels genomic DNA, and SPY555-actin, which labels F-actin, were validated in the mouse embryo where they produced high contrast labelling with similar results to microinjection of fluorescent mRNAs and produced offspring at a similar rate to nondyed control embryos. Live imaging data using these dyes enabled 3-dimensional scans of the embryo at 5- to 10-minute intervals of the following central events during preimplantation development: the main phases of mitosis, visualizing the major changes in cell shape that characterize embryo compaction at the 8-cell stage, detecting cell polarization at the 8-cell stage, establishing apical F-actin rings at the 16-cell stage, tracking the expansion and zippering of F-actin rings, detecting the first internalized cells within the 16-cell embryo, and visualizing blastocyst expansion and hatching from the zona pellucida. Cleavage-stage human IVF embryos were then studied using the fluorescent dyes to track early cellular and morphogenetic processes. Early cell-cycle dynamics and mitotic stages revealed that the duration of human mitosis is similar to that of mice, but interphase is 27% ± 4% longer in humans (16.1 ± 0.9 vs 12.7 ± 0.4 hours; P < 0.01). Using live imaging, compaction dynamics such as increased cell-cell contact and angle between apical membranes with a decrease in cell sphericity were observed beginning at the 12-cell stage and differed significantly from development in mice. In comparison to mice, human compaction was found to be more asynchronous and did not have clear links to apical polarization or inner-outer segregation. Next, chromosomal segregation was analyzed to determine if this approach allowed detection of segregation errors in the human embryo leading to aneuploidy. Lagging chromosomes detected in human embryos using SPY-DNA appeared morphologically similar to those found in mouse embryos and had similar segregation dynamics. During blastocyst expansion, a subset of trophectoderm cell nuclei forms protruding bud-like that is shed into cytoplasm producing cytoplasmic DNA structures (cytDNA), suggesting an additional process of DNA loss different from chromosome segregation errors during mitosis. A perinuclear keratin network developing at the early cavitation stage appears to protect from formation of cytDNA structures, and the mechanical stress of blastocyst expansion appeared to disrupt the keratin network in certain cells, increasing DNA shedding. Next, trophectoderm biopsy was conducted in mouse, and human embryos to determine if the mechanical stress would increase DNA shedding. Biopsy of human blastocysts resulted in a significant increase in nuclear budding (6.0% vs 0.70%; P = 0.0022), suggesting a link between mechanical stress and DNA shedding. This study demonstrates the use of fluorescent dyes and live imaging in characterization of key cellular and morphogenetic processes patterning the preimplantation human embryo and describes a process of DNA shedding in response to mechanical stressors that warrants future research.

Cortical tension drug screen links mitotic spindle integrity to Rho pathway

Mechanical force generation plays an essential role in many cellular functions, including mitosis. Actomyosin contractile forces mediate changes in cell shape in mitosis and are implicated in mitotic spindle integrity via cortical tension. An unbiased screen of 150 small molecules that impact actin organization and 32 anti-mitotic drugs identified two molecular targets, Rho kinase (ROCK) and tropomyosin 3.1/2 (Tpm3.1/2), whose inhibition has the greatest impact on mitotic cortical tension. The converse was found for compounds that depolymerize microtubules. Tpm3.1/2 forms a co-polymer with mitotic cortical actin filaments, and its inhibition prevents rescue of multipolar spindles induced by anti-microtubule chemotherapeutics. We examined the role of mitotic cortical tension in this rescue mechanism. Inhibition of ROCK and Tpm3.1/2 and knockdown (KD) of cortical nonmuscle myosin 2A (NM2A), all of which reduce cortical tension, inhibited rescue of multipolar mitotic spindles, further implicating cortical tension in the rescue mechanism. GEF-H1 released from microtubules by depolymerization increased cortical tension through the RhoA pathway, and its KD also inhibited rescue of multipolar mitotic spindles. We conclude that microtubule depolymerization by anti-cancer drugs induces cortical-tension-based rescue to ensure integrity of the mitotic bipolar spindle mediated via the RhoA pathway. Central to this mechanism is the dependence of NM2A on Tpm3.1/2 to produce the functional engagement of actin filaments responsible for cortical tension.

Suppression of LPS-activated inflammatory responses and chromosomal histone modifications in macrophages by micropattern-induced nuclear deformation.

Macrophages are important immune effector cells which participate various physiological and pathological conditions. Numerous studies have demonstrated the regulation of macrophage phenotype by micropatterns. It is well accepted that micropatterns affect cellular behaviors through changing cell shape and modulating the associated mechanical sensors on the plasma membrane and cytoskeleton. However, the role of nucleus, which serves as a critical physical sensing device, is often ignored. Herein, we found the nuclear deformation and the subsequently increased chromosomal histone methylation (H3K36me2) may contribute to the micropattern-induced suppression of macrophage inflammatory responses. Specifically, macrophages on micropatterned surfaces expressed lower levels of key inflammatory genes, compared with those on flat surfaces. Further investigation on macrophage nuclei showed that micropatterned surfaces cause shrinkage of nucleus volume and compaction of chromatin. Moreover, micropatterned surfaces elevated the methylation level of H3K36me2 in macrophages, while decreased the methylation level of H3K4me3. Our study provides new mechanistic insight into how micropatterns affect macrophage phenotype and highlights the importance of nuclear shape and chromatin histone modification in mediating micropattern-induced change in cell behaviors.

Smooth Elongation ofPavement Cells Induced by RIC1 Overexpression Leads to Marginal Protrusions ofthe Cotyledon inArabidopsis thaliana.

The interdigitated pavement cell shape is suggested to be mechanically rational at both the cellular and tissue levels, but the biological significance of the cell shape is not fully understood. In this study, we explored the potential importance of the jigsaw puzzle-like cell shape for cotyledon morphogenesis in Arabidopsis. We used a transgenic line overexpressing a Rho-like GTPase-interacting protein, ROP-INTERACTIVE CRIB MOTIF-CONTAINING PROTEIN 1 (RIC1), which causes simple elongation of pavement cells. Computer-assisted microscopic analyses, including virtual reality observation, revealed that RIC1 overexpression resulted in abnormal cotyledon shapes with marginal protrusions, suggesting that the abnormal organ shape might be explained by changes in the pavement cell shape. Microscopic, biochemical and mechanical observations indicated that the pavement cell deformation might be due to reduction in the cell wall cellulose content with alteration of cortical microtubule organization. To examine our hypothesis that simple elongation of pavement cells leads to an abnormal shape with marginal protrusion of the cotyledon, we developed a mathematical model that examines the impact of planar cell growth geometry on the morphogenesis of the organ that is an assemblage of the cells. Computer simulations supported experimental observations that elongated pavement cells resulted in an irregular cotyledon shape, suggesting that marginal protrusions were due to local growth variation possibly caused by stochastic bias in the direction of cell elongation cannot be explained only by polarity-based cell elongation, but that an organ-level regulatory mechanism is required.

Fluorescence imaging deformability cytometry: integrating nuclear structure with mechanical phenotyping

Mechanical measurements of cells can provide unique insights into cell state and disease processes. The overall mechanical properties of cells can be heavily affected by the stiffest organelle, the nucleus. However, it is challenging to fully characterize internal nuclear structures in most cell mechanical measurement platforms. Here, we demonstrate single-cell deformability measurements of whole cells and stained nuclei in a fluorescence imaging flow cytometry platform. We also introduce bending energy derived metrics as a way to normalize measurements of cytoskeletal cortex and nuclear shape changes of cells and demonstrate the utility of relative deformability distributions to characterize populations of cells. We apply the platform to measure changes in cell biophysical properties during the process of NETosis, whereby neutrophils undergo drastic nuclear restructuring. We characterize cell size, deformability, and nuclear structure changes and their correlations in thousands of neutrophils undergoing NETosis, a process implicated in development of critical disease states, such as sepsis. This platform can aid in understanding heterogeneity in deformability in cell populations and how this may be influenced by nuclear or internal structure changes.Graphical

Slow Interstitial Fluid Flow Activates TGF-β Signaling and Drives Fibrotic Responses in Human Tenon Fibroblasts.

Fibrosis limits the success of filtering glaucoma surgery. We employed 2D and 3D in vitro models to assess the effects of fluid flow on human tenon fibroblasts (HTF). HTF were exposed to continuous or pulsatile fluid flow for 48 or 72 h, at rates expected at the transscleral outflow site after filtering surgery. In the 2D model, the F-actin cytoskeleton and fibronectin 1 (FN1) were visualized by confocal immunofluorescence microscopy. In the 3D model, mRNA and whole cell lysates were extracted to analyze the expression of fibrosis-associated genes by qPCR and Western blot. The effects of a small-molecule inhibitor of the TGF-β receptor ALK5 were studied. Slow, continuous fluid flow induced fibrotic responses in the 2D and 3D models. It elicited changes in cell shape, the F-actin cytoskeleton, the deposition of FN1 and activated the intracellular TGF-β signaling pathway to induce expression of fibrosis-related genes, such as CTGF, FN1 and COL1A1. ALK5-inhibition reduced this effect. Intermittent fluid flow also induced fibrotic changes, which decreased with increasing pause duration. Slow interstitial fluid flow is sufficient to induce fibrosis, could underlie the intractable nature of fibrosis following filtering glaucoma surgery and might be a target for antifibrotic therapy.

Comparative Evaluation of the Effect of Copper Oxide and Copper Sulfate Nanoparticles on Structural and Functional Characteristics of Thalassiosira weissflogii under Conditions of Enrichment Cultivation // Russian Journal of Plant Physiology.

The effect of copper oxide nanoparticles (500, 1000, 2000 μg/L) and copper ions (37.5, 75, 150 μg/L) on the morphological, structural-functional, and fluorescent parameters of diatom microalgae Thalassiosira weissflogii under conditions of long-term cultivation was studied. It was shown that copper in ionic form is more toxic for this microalgae species than in the form of a nanooxide. The nature of the effect of copper in ionic and nanoform on cells Thalassiosira weissflogii has both similarities and significant differences. The difference in the effect of the studied toxicants on the growth of algae and the performance of photosynthetic apparatus was revealed. The addition of copper ions into the cultivation medium led to long lag phase during the initial stage of the experiment, followed by the restoration of growth on days 3–6 of exposure. An increase in the concentration of copper oxide nanoparticles in the medium caused inhibition of algae growth without a pronounced lag phase. With an increase in the concentration of Cu2+ in the culture medium, a decrease in the quantum efficiency of light energy utilization by the PS II photosynthetic complex and the maximum relative electron transport rate were observed, while copper oxide nanoparticles had an insignificant effect on the efficiency of the photosynthetic apparatus ofThalassiosira weissflogii. With an increase in the concentration of copper, both in the ionic form and in the form of nanooxide, increase in cell volume, changes of cell shape and granularity, an increase in the production of reactive oxygen species, suppression of enzymatic activity and a decrease in autofluorescence values of individual cells in the red region of the spectrum were observed.

Endoplasmic Reticulum Stress Inducer Dithiothreitol Affects the Morphology and Motility of Cultured Human Dermal Fibroblasts and Fibrosarcome HT1080 Cell Line

Some inducers of endoplasmic reticulum (ER) stress can affect the motility of normal and tumor cells. However, it is unknown what mechanisms mediate this effect and whether it is a consequence of ER stress. The aim of our work was to study the effect of the ER stress inducer dithiothreitol (DTT) on morphological features reflecting the locomotor properties of cells, as well as directly on the migratory properties of cultured human dermal fibroblasts and fibrosarcoma HT1080 cells. We have shown that DTT causes disruption of the organization of actin cytoskeleton in both types of cells, which is accompanied by a change in the cell surface and shape of cells, as well as a decrease in their spreading area. In addition, a decrease in the number of focal contacts was observed in dermal fibroblasts. DTT also reduced the motility of dermal fibroblasts and fibrosarcoma cells. To analyze cell motility and determine the moment of its change, we developed a method which showed that the change in the migratory properties of fibrosarcoma cells cultured with DTT began earlier than in dermal fibroblasts. Thus, activation of ER stress by DTT is accompanied by a change in the organization of the actin cytoskeleton and motility in normal and tumor human cells. Consequently, ER stress triggered by various inducers with different mechanisms of action affects the motility of normal and tumor cells, which must be taken into account when developing antitumor drugs that cause cell death through activation of ER stress.