Changes In Cellular Structure Research Articles

Negative effects of desiccation on the protein sorting and post-translational modification

Bryophytes as the first land plants are believed to have colonized the land from a fresh water origin, requiring adaptive mechanisms that survival of dehydration. Physcomitrella patens is such a non-vascular bryophyte and shows rare desiccation tolerance in its vegetative tissues. Previous studies showed that during the course of dehydration, several related processes are set in motion: plasmolysis, chloroplast remodeling, and microtubule depolymerization. And proteomic alteration supported the cellular structural changes in respond to desiccation stress.1 In this addendum, we report that Golgi bodies are absent and adaptor protein complex AP-1 large subunit is down-regulated during the course of dehydration. Those phenomena may be adverse in protein posttranslational modification, protein sorting, and cell walls synthesis under the desiccation condition.

Genetic control of cellular quiescence in S. pombe

Transition from proliferation to quiescence brings about extensive changes in cellular behavior and structure. However, the genes that are crucial for establishing and/or maintaining quiescence are largely unknown. The fission yeast Schizosaccharomyces pombe is an excellent model in which to study this problem, because it becomes quiescent under nitrogen starvation. Here, we characterize 610 temperature-sensitive mutants, and identify 33 genes that are required for entry into and maintenance of quiescence. These genes cover a broad range of cellular functions in the cytoplasm, membrane and nucleus. They encode proteins for stress-responsive and cell-cycle kinase signaling pathways, for actin-bound and osmo-controlling endosome formation, for RNA transcription, splicing and ribosome biogenesis, for chromatin silencing, for biosynthesis of lipids and ATP, for cell-wall and membrane morphogenesis, and for protein trafficking and vesicle fusion. We specifically highlight Fcp1, a CTD phosphatase of RNA polymerase II, which differentially affects the transcription of genes that are involved in quiescence and proliferation. We propose that the transcriptional role of Fcp1 is central in differentiating quiescence from proliferation.

Changes in texture, cellular structure and cell wall composition in apple tissue as a result of freezing

Apple texture is one of the critical quality features for the consumer. Texture depends on several factors that are difficult to control and which change with freezing. To better understand the mechanisms involved in the texture degradation of apple tissues following freezing/thawing, our approach was to combine mechanical properties, cellular structure and cell wall composition measurements on fresh and thawed apples (Granny Smith) after three different freezing protocols (at -20 degrees C, -80 degrees C and -196 degrees C). This work highlighted the interest of applying macrovision and image texture analysis to quantify the freezing effects on cellular structure and ice crystal size. Freezing at -20 degrees C and after immersion into liquid nitrogen were the protocols affecting the most fruit texture leading to cell membrane breakage resulting in cell wall collapse and tissue breakage, respectively, which accounted for the mechanical behaviour of the samples. All freezing ! protocols induced vacuole burst showing that the turgor pressure preservation remains critical during the freezing process.

The distribution of oil in the oat grain

High-lipid oat is a potential oil crop. Chemical and microscopical analyses have shown that the major part of the grain lipids are stored in the endosperm. While oil bodies are intact in the aleurone layer, scutellum and embryo, they have less associated proteins (oleosins) and undergo fusion in the starchy endosperm. In this report, we document the distribution of lipids in the endosperm microscopically. Underneath the aleurone layer, lipids are most abundant in the subaleurone cells and in the endosperm cells in the vicinity of the scutellum and embryo. Thus the major areas of oil storage are close to the living tissues of the grain, the sites of enzyme production in connection with germination and mobilization. The documentation of cellular structural changes, and implication of the fused state of oil bodies, during germination, remains to be elucidated.

Modulation of Programmed Cell Death in a Model System of Xylogenic Zinnia (Zinnia Elegans) Cell Culture

ABSTRACTProgrammed cell death is an integral part of the latest stage of differentiation of the tracheary elements of plant xylem vascular system. In this study, by applying a pharmacological approach with specific peptide inhibitors, we have elucidated the involvement of plant caspase-like proteases in cell death signaling during vessel elements formation in xylogenic zinnia (Zinnia elegans) cell culture. Cell culture was isolated from zinnia leaves and exposed to chemical treatments. Broad spectrum caspase inhibitor, caspase 1 and caspase-3 inhibitors were administrated to the cell culture where the cells were induced to differentiate with the addition of 1 mg/L benzylaminopurine and 0.1 mg/L α-naphthalene-acetic acid. The differentiation was substantially suppressed in presence of 100 nM concentration of the inhibitors. This indicates that the re-differentiation in cultured mesophyll zinnia cells is a PCD event that most probably occurs through signaling involving caspase-like proteases. The reported results are the first that provide evidence for participation of plant caspase-related enzymes in xylogenesis in zinnia. Laser scanning confocal microscopy revealed differentiation associated structural cellular changes, including formation of large vacuole, secondary wall thickenings, tonoplast rupture and cell autolysis to form hollow dead tracheary elements‥

Characterization of the molecular phenotype of two arrhythmogenic right ventricular cardiomyopathy (ARVC)-related plakophilin-2 (PKP2) mutations

Arrhythmogenic right ventricular cardiomyopathy (ARVC) has been linked to mutations in desmosomal proteins, including plakophilin-2 (PKP2). Little is known about the changes in cellular function and structure that follow expression of ARVC-relevant PKP2 mutations. The purpose of this study was to investigate the function and distribution of an ARVC-relevant PKP2 mutant where arginine at position 79 was replaced by a stop codon (R79x). Results were compared with those obtained with mutation 179fs (frameshift at position 179). Mutant constructs were introduced by adenoviral infection into neonatal rat ventricular myocytes in culture. Both mutant proteins failed to preferentially localize to sites of cell-cell apposition. Their expression did not disrupt localization of endogenous PKP2, connexin-43 (Cx43), or desmoplakin (DP). However, we observed reduced abundance of Cx43 after R79x expression. Early truncation of PKP2 at position 79 also prevented its physical interaction with both DP and Cx43. Finally, R79x expression correlated with loss of expression of HSP90, a protein relevant to cardiomyocyte apoptosis. These results provide the first observations of the cellular/molecular phenotype consequent to these PKP2 mutations and give insight into the possible cellular substrates that lead to ARVC.

Changes in Cellular Structures Revealed by Ultra-high Resolution Retinal Imaging in Optic Neuropathies

To study the integrity of inner and outer retinal layers in patients with various types of optic neuropathy by using high-resolution imaging modalities. Three high-resolution imaging systems constructed at the University of California Davis were used to acquire retinal images from patients with optic neuropathy: (1) adaptive optics (AO)-flood-illuminated fundus camera, (2) high-resolution Fourier domain optical coherence tomography (FDOCT), and (3) adaptive optics-Fourier domain optical coherence tomography (AO-FDOCT). The AO fundus camera provides en face images of photoreceptors whereas cross-sectional images (B-scans) of the retina are obtained with both FDOCT and AO-FDOCT. From the volumetric FDOCT data sets, detailed thickness maps of a three-layer complex consisting of the nerve fiber (NF), ganglion cell (GC), and inner plexiform (IP) layers were created. The number of visible cones in the en face images of photoreceptors was then compared with visual sensitivity maps from Humphrey visual field (HVF; Carl Zeiss Meditec, Inc., Dublin, CA) testing, as well as FDOCT and AO-FDOCT images, including the thickness maps of the NF-GC-IP layer complex. Five types of optic neuropathy were studied: (1) optic neuritis with multiple sclerosis (MS), (2) idiopathic intracranial hypertension (pseudotumor cerebri), (3) nonarteritic anterior ischemic optic neuropathy (NAION), (4) optic nerve head drusen with NAION, and (5) systemic lupus erythematosus with MS and arthritis. With permanent visual field loss and thinning of the NF-GC-IP layer complex, cone photoreceptors showed structural changes, making them less reflective, which caused the appearance of dark spaces in the en face images (hence, reduced number of visible cones) and indistinct outer retinal layers in OCT images. However, when the visual field loss was only transient, with a normal NF-GC-IP layer complex, there were no detectable abnormalities in cone photoreceptors (i.e., they were densely packed and had distinct photoreceptor layering in the OCT images). Cone photoreceptors show structural changes when there is permanent damage to overlying inner retinal layers. There was a positive relation between the thickness of the three-layer inner retinal complex, visual sensitivity, and integrity of the cone mosaic.

Bio-Damages of Materials. Adhesion of Microorganisms on Materials Surface

Adhesion interaction of the most widely distributed species of microscopic fungi: Aspergillus niger, Trichoderma viride, Penicillium funiculosum, Aspergillus terreus to surfaces of materials (polymers, metals) is studied. The force of adhesion interaction was measured by the method of centrifugal detachment. Based on the analysis of kinetic curves the macroscopic characteristics of adhesion micro-organism–metal surface were obtained. We show on the example of Aspergillus niger that stochastic nature of adhesion of microorganisms cells is caused by heterogeneity of support surface, heterogeneity of conidium sizes, and their distribution by forces of adhesion obeys the Gauss law. We established that structure of cellular wall of microscopic fungi was changed in dependence on age, and change of force of adhesion interaction correlated with changes in cellular wall structure of microscopic fungi, and dominating role in strengthening of adhesion interaction was played by increase of albuminous components concentration in surface layer of cell.

EFFECTIVE DIFFUSION COEFFICIENTS BEHAVIOR IN OSMOTIC DEHYDRATION OF APPLE SLICES CONSIDERING SHRINKING AND LOCAL CONCENTRATION DEPENDENCE

ABSTRACT The mass transfer during osmotic dehydration of apple slices immersed in 40, 50 and 60% (w/w) aqueous sucrose solutions was investigated to evaluate the influence of solution concentration on diffusivities. In the mathematical model, the diffusion coefficients were functions of the local water and sucrose concentration. The mass transfer equations were, simultaneously, solved for water and sucrose using an implicit numerical method. Material coordinates following the shrinkage of the solid were used. The predicted concentration profiles were integrated and compared to experimental data, showing a reasonable agreement with the measured data. On average, the effective diffusion coefficients for water and sucrose decreased as the osmotic solution concentration increased; that is the behavior of the binary coefficients in water–sucrose solutions. However, the diffusivities expressed as a function of the local concentration in the slices varied between the treatments. Water diffusion coefficients showed a remarkable variation throughout the slice and unusual behavior, which was associated to the cellular structure changes observed in tissue immersed in osmotic solutions. Cell structure changes occurred in different ways: moderate plasmolysis at 40%, accentuated plasmolysis at 50% and generalized damage of the cells at 60%. Intact vacuoles were observed after a long time of exposure (30 h) to 40 and 50% solutions. Effects of the concentration on tissue changes make it difficult to generalize the behavior of diffusion coefficients. PRACTICAL APPLICATIONSThe main innovation introduced in this study is represented by the model formulation that allows simulation of the concentration profiles during osmotic dehydration with a reasonable degree of accuracy. The model is useful for the design and control of this process and of further operations such as convective drying, as nonhomogeneous initial conditions can be established. In addition, the diffusivities expressed as a function of the local concentration in the slices allows interpretation of some of the physical changes in plant tissues exposed to concentrated solutions.

Changes of cellular structure of potato tuber parenchyma tissues during storage

The presented work is continuation of researches on cellular structure of potato tuber parenchyma tissue. It concerns changes of the potato tuber cellular structure parameters during storage. Tubers of two varieties: Andromeda and Pasat were tested, 5 tubers for each variety and storage period. Cylindrical samples 10 mm in diameter and 1 mm thick were taken out of two types of tissues − potato pith and internal parenchyma from each tuber. Images of the tissues in natural state were taken with optical confocal microscope. Technique elaborated earlier by the author was used to obtain images containing number of cells sufficient for statistical analysis. As the result of analysis performed following mean values parameters of cell size and shape were used: surface area of plane section of the cell A (μm<sup>2</sup>) and cell elongation E. The results show differences between cell size for potato pith and internal parenchyma Andromeda variety and storage period. For this smaller values of the area of cell were obtained just after harvest. No differences of area of cell were observed for Pasat variety, and no differences in elongation of cell were observed for all varieties.

Morphometric analysis for early detection of changes in cellular structure in a toxicological experiment

This paper presents a method for semi-automatic analysis of morphometry in image cytometry studies. We examine morphological changes in neuroblastoma cells caused by a toxin. Nuclei are automatically recognized from images using a constrained seeded region growing algorithm. The shape of the nuclei is quantified by fitting ellipses to the identified regions. Features such as centroids, elongation, orientation and size are extracted from this fitting process. Under certain assumptions, it is demonstrated that the log elongation measurement has an asymptotically normal distribution whose variance is dependent only on object size. This allows weighted linear models to be fitted to elongation measurements. Hypothesis tests show that over time, there is a significant elongation due to application of the toxin. The other variables are not significant, but there is a significant 'image' effect. The scientific implications of these findings are considered.

Basic Science for the Clinician 43

Growth factors, cytokines, chemokines, apoptotic stimuli, TLR ligands, stress-a lot can happen to a cell in day-to-day living, but these are extracellular phenomena, and all influence the inner workings of the cell. Once the ligand binds to the receptor, or the stress, occurs, changes occur within the cell that eventuate in intranuclear transcription of new genes, subsequent changes in cellular structure and function, and often in the release of chemicals that transmit signals to self (autocrine) and other cells (paracrine and juxtacrine). Often, these changes occur due to the activation of cascades of kinases, a perireceptor choreography that is only now being elucidated. The human "kinome" (the various families of kinases) is very complex; we will limit ourselves in this discussion to the mitogen-activated protein kinases.

Central haemodynamics and peripheral muscle function during exercise in patients with chronic heart failure

In this narrative review of the current literature, we examine the central and peripheral mechanisms responsible for the exercise intolerance of chronic heart failure and highlight briefly the benefits of exercise training in the treatment of this debilitating disorder. Specifically, we identify the common finding of reduced cardiac output reserve during exercise conditions leading to decreased exercise tolerance. We also reveal that the stroke volume response to exercise varies depending on the individual patient, the presence of mitral regurgitation, and the aetiology of heart failure. Chronic heart failure patients with left ventricular systolic dysfunction appear able to use the Frank-Starling mechanism to compensate (in part) for their decreased contractile reserve. Patients with left ventricular diastolic dysfunction have normal contractile function; however, they are unable to make use of the Frank-Starling mechanism during exercise conditions. We also reveal that pericardial constraint may limit diastolic filling and exercise capacity in patients with chronic heart failure. It appears that interventions that reduce pericardial constraint and mitral regurgitation enhance diastolic filling and increase exercise tolerance. A series of peripheral muscle changes also occur, including changes in muscle mass, cellular structure, energy metabolism, and blood flow. Each of these factors is associated with decreased exercise capacity and the symptoms of chronic heart failure. Exercise training has been shown to improve both central haemodynamics and peripheral muscle function leading to improvements in exercise capacity, functional status, and overall quality of life in patients with chronic heart failure.

Extracorporeal Ablation of Uterine Fibroids With High-Intensity Focused Ultrasound

The purpose of this study was to evaluate the therapeutic efficacy of high-intensity focused ultrasound (HIFU) in the treatment of uterine fibroids by using imaging and histopathologic examination. From May 2004 to June 2005, 119 consecutive patients with 187 uterine fibroids were treated with HIFU. Sixty-two fibroids received ultrasonographically guided needle puncture biopsy 1 week before and after HIFU treatment, respectively, to confirm the diagnosis and to assess the early therapeutic efficacy. Hematoxylin-eosin staining and electron microscopy were performed to characterize more subtle phenotypic changes to determine treatment success. Immediate therapeutic effects were assessed at follow-up with Doppler ultrasonography and computed tomography or magnetic resonance imaging. All patients were followed for 6 to 12 months to observe long-term therapeutic effects. Fibroid mean diameters, volumes, and reduction rates 1, 3, 6, and 12 months after HIFU treatment were calculated and compared with 1-way analysis of variance and Student-Newman-Keuls tests. No severe complications were observed after HIFU ablation. Fifty-one (82.3%) of 62 biopsy specimens revealed obvious signs of necrosis under light microscopy, and more subtle changes in cellular structure that indicated nonviability could be found in 60 specimens (96.8%) under electron microscopy. However, viable cells still could be found in 16 specimens (25.8%). Follow-up images showed absence or reduction of blood supply in the lesions after HIFU ablation. Median reductions in tumor size as a percentage of initial tumor volume at 1, 3, 6, and 12 months after HIFU treatment were 21.2%, 29.6%, 44.8%, and 48.7%, respectively. Imaging and histopathologic evidence directly validate HIFU ablation as an effective treatment of uterine fibroids.

Influence of Processing Temperature on Microcellular Injection‐Moulded Wood–Polypropylene Composites

AbstractSummary: Microcellular wood fibre reinforced polymer materials are significant because of their possibility to reduce the density of automotive components through microcellular structure, process and product part advantages, and as a new development with bio‐fibre strengthened plastics. Soft wood fibre reinforced PP composites in box part and panel shape were prepared by an injection moulding process. Polymeric microspheres as a chemical foaming agent (endothermic) were used to produce the microcellular composites. The influence of injection moulding processing temperature on the microcellular structure and properties (tensile and flexural properties, notched charpy impact strength) was investigated by varying the temperature over the 150–170 °C, 160–180 °C and 170–190 °C. A comparative study of cell morphology, weight reduction and mechanical properties was conducted between box part and panel. Microcell morphology, cell size, shape and distribution were investigated using scanning electron micrographs. The results indicated that the lower processing temperature should be below the range of 170–190 °C and processing temperature at 160–180 °C, where the composites showed finer cellular structure compared to other processing temperatures. The mechanical properties did not differ with the variation of processing temperature regardless of composite types (box part or panel). Cellular structure changes in the box part were found considering near or far from injecting point.Microcellular injection‐moulded box part (geometry: 150 × 100 × 70 mm3 in size) of soft wood fibre–PP composites.magnified imageMicrocellular injection‐moulded box part (geometry: 150 × 100 × 70 mm3 in size) of soft wood fibre–PP composites.

Receptor tyrosine kinases: role in cancer progression.

The mutation and deregulation of rtks can lead to a wide variety of changes in cellular structure and function, all of which contribute to the malignant phenotype and pathologic behaviour of human cancer. The progress in recent years on the clinical validation of molecularly targeted drugs that inhibit rtks has demonstrated that, in appropriately selected patients, treatment can alter disease progression and survival. Rational drug design will benefit from computational biology and a detailed understanding at the structural level both of the kinase domains and of the ligand binding sites of these receptors. The large tissue and serum repositories from patients in clinical trials will also allow outcome to be linked to molecular changes observed in tumours.

Development and assessment of morphologic criteria for diagnosing gastric cancer using confocal endomicroscopy: an ex vivo and in vivo study

The Confocal Endomicroscopy System (Optiscan Pty Ltd. and Pentax Corp.) is a newly developed imaging tool that uses laser light and optical technology to visualize living tissue at the cellular level. Digital images of cells magnified 1000-fold appear in real time on a computer screen, which enables immediate detection of changes in cellular structure without the need for a biopsy. The aim of this study was to assess the features of the cellular architecture of cancerous tissue that can be used in the differential diagnosis of cancerous tissue and normal mucosa using this system's image-processing software. A total of 27 gastric cancers were examined ex vivo using confocal endomicroscopy. A fluorescent contrast agent, acriflavine, was applied topically to normal and to cancerous mucosa. In vivo imaging of the gastric mucosa after intravenous injection of fluorescein sodium was also performed in nine patients with gastritis or gastric cancer. The nuclear area in the ex vivo specimens was calculated using Scion Image software. The mean nuclear area of cancer cells was found to be significantly larger than that of normal cells in 18/27 gastric cancers (67 %). The mean nuclear area of the cancers tended to be larger than that of normal mucosa, especially in cases of differentiated adenocarcinoma. In more than half the cases, it was possible to diagnose malignancy automatically using confocal endomicroscopy and image-processing software without the need for biopsy and pathological examination. In vivo imaging of cancerous lesions showed irregularity in cellularity and vascularity. The ability of this imaging device to differentiate between normal tissue and cancerous tissues gives it potential value as a new screening tool for early detection of malignancy.

The evolution of development inStreptomycesanalysed by genome comparisons

There is considerable information about the genetic control of the processes by which mycelial Streptomyces bacteria form spore-bearing aerial hyphae. The recent acquisition of genome sequences for 16 species of actinobacteria, including two streptomycetes, makes it possible to try to reconstruct the evolution of Streptomyces differentiation by a comparative genomic approach, and to place the results in the context of current views on the evolution of bacteria. Most of the developmental genes evaluated are found only in actinobacteria that form sporulating aerial hyphae, with several being peculiar to streptomycetes. Only four (whiA, whiB, whiD, crgA) are generally present in nondifferentiating actinobacteria, and only two (whiA, whiG) are found in other bacteria, where they are widespread. Thus, the evolution of Streptomyces development has probably involved the stepwise acquisition of laterally transferred DNA, each successive acquisition giving rise either to regulatory changes that affect the conditions under which development is initiated, or to changes in cellular structure or morphology.

Effects of Cellular Fine Structure on Scattered Light Pattern

Biological cells are complex in both morphological and biochemical structure. The effects of cellular fine structure on light scattered from cells are studied by employing a three-dimensional code named AETHER which solves the full set of Maxwell equations by using the finite-difference time-domain method. It is shown that changes in cellular fine structure can cause significant changes in the scattered light pattern over particular scattering angles. These changes potentially provide the possibility for distinguishability of cellular intrastructures. The effects that features of different intrastructure have on scattered light are discussed from the viewpoint of diagnosing cellular fine structure. Finally, we discuss scattered light patterns for lymphocyte-like cells and basophil-like cells.

AFM studies of environmental effects on nanomechanical properties and cellular structure of human hair

Characterization of cellular structure and physical and mechanical properties of hair are essential to develop better cosmetic products and advance biological and cosmetic science. Although the morphology of the cellular structure of human hair has been traditionally investigated using scanning electron microscopy and transmission electron microscopy, these techniques provide limited capability to in situ study of the physical and mechanical properties of human hair in various environments. Atomic force microscopy (AFM) overcomes these problems and can be used for characterization in ambient conditions without requiring specific sample preparations and surface treatment. In this study, film thickness, adhesive forces and effective Young's modulus of various hair surfaces were measured at different environments (humidity and temperature) using force calibration plot technique with an AFM. Torsional resonance mode phase contrast images were also taken in order to characterize the morphology and cellular structure changes of human hair at different humidity. The correlation between the nanomechanical properties and the cellular structure of hair is discussed.