Cup cells: structure and distribution of a unique class of epithelial cells in guinea pig, rabbit, and monkey small intestine.
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Animals↗
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Immunocytochemical localization of cyclo-oxygenase isoforms in cultured human airway structural cells.
BACKGROUND: Cyclo-oxygenase (COX) exists as two isoforms, COX-1, the constitutive isoform, and COX-2, which is inducible by cytokines or inflammatory stimuli and may participate in airway inflammation. OBJECTIVE: To determine the basal distribution of COX isoforms, and their regulation by interleukin-1 beta (IL-1beta), bradykinin (BK) and dexamethasone (Dex) in cultured airway structural cells. METHODS: We measured COX-1 and COX-2 in cultured human airway smooth muscle (HASM) cells, MRC5 fibroblasts and normal human epithelial cells (NHBE) using immunocytochemical analysis. RESULTS: The majority of all types of untreated cultured cells expressed COX-1 (75% of HASM, 75% of MRC5 fibroblasts and 72% of NHBE cells). Fibroblasts and smooth muscle cells showed low constitutive COX-2 expression (2 and 8%, respectively) but this was higher in NHBE cells (28%). IL-1beta (24 h incubation) or BK (4 h incubation) had no effect on COX-1 expression in any of the cells studied. In contrast, there was a two- and 1.5-fold rise in the percentage of NHBE cells expressing COX-2; a 7.5- and sixfold rise in the percentage of HASM cells expressing COX-2 and a 33.5- and 20.5-fold increase in the percentage of fibroblasts expressing COX-2 after IL-1beta or BK treatment, respectively. Pretreatment with dexamethasone abolished IL-1beta- and BK-stimulated COX-2 induction in all cells studied. CONCLUSION: COX-1 is expressed constitutively in human airway fibroblasts, smooth muscle and epithelial cells but epithelial cells also show constitutive expression of COX-2. Both IL-1beta and BK induced COX-2 expression in all cells studied and this induction was blocked by dexamethasone. Immunocytochemical techniques can be successfully used to detect the distribution of COX isoforms in cell cultures.
Blotting, Western↗
The MinE ring: an FtsZ-independent cell structure required for selection of the correct division site in E. coli.
E. coli cell division is mediated by the FtsZ ring and associated factors. Selection of the correct division site requires the combined action of an inhibitor of FtsZ ring formation (MinCD) and of a topological specificity factor that somehow prevents MinCD action at the middle of the cell (MinE). Here we show that a biologically active MinE-Gfp fusion accumulates in an annular structure near the middle of young cells. Formation of the MinE ring required MinD but was independent of MinC and continued in nondividing cells in which FtsZ function was inhibited. The results indicate that the MinE ring represents a novel cell structure, which allows FtsZ ring formation at midcell by suppressing MinCD activity at this site.
Adenosine Triphosphatases↗
The effects of morphine self-administration on cortical pyramidal cell structure in addiction-prone lewis rats.
The consumption of drugs of abuse provokes sensitization, the development of tolerance, dependency, and eventually addiction. It is thought that these events are partially a consequence of drug-induced alterations in the organization of neuronal circuits in specific areas of the brain. In the present study, we have used intracellular injections of lucifer yellow to examine the alterations that may occur in cortical pyramidal neurons of addiction-prone Lewis rats following 15 days of self-administration of morphine. Specifically, the effects of morphine on the structure, size and branching complexity of the basal dendrites, and spine density were determined in the basal dendritic arbors of layer III pyramidal neurons in both the prelimbic and motor cortex. We found that following morphine self-administration, there was a reduction in the size and branching complexity of the dendritic arbors of pyramidal cells in the motor cortex. In contrast, prelimbic pyramidal neurons from these morphine-treated animals had larger and longer basal dendritic arbors. Furthermore, the spine density on pyramidal neurons was higher in both cortical regions of morphine self-administered rats. These results suggest that at least part of the behavioral changes produced by repeated opiate administration may be attributed to alterations in pyramidal cell structure.
Analgesics, Opioid↗
Contractile proteins in cell structure and function.
1. The cytoplasm of cells is a colloidal network of contractile proteins. Actin filaments are the major components of this network. Other contractile proteins interact with these filaments to create structural rigidity and movement. 2. The structure and function of contractile proteins is striated muscles is well characterized and thus provides a good example for extrapolitation to an analysis of contractile-protein structure and function of nonmuscle cells. However, the interaction of contractile proteins of various cells may be unique. 3. The study of contractile proteins in cells other than muscle has distinct difficulties: (a) The proteins are present in much lower concentration than in muscle, and only a few cell types are obtainable for study in quantities comparable to muscle. (b) Proteolysis and other detriments may be more severe in nonmuscle cells. (c) The organization of contractile proteins is difficult to define in nonmuscle cells. (d) The effort is diffuse; investigations examine a wide variety of different, or less commonly the same, cells. Reflecting these difficulties, a catalogue of putative nonmuscle cell fucntions related to contractile proteins reveals no one system to be definitively worked out. Nevertheless, the ubiquity of contractile proteins and the obvious importance of their intractions presages increasing relevancy for physiology and medicine.
Actinin↗
Androgenic gland cell structure and spermatogenesis during the molt cycle and correlation to morphotypic differentiation in the giant freshwater prawn, Macrobrachium rosenbergii.
The freshwater prawn Macrobrachium rosenbergii shows three male morphotypes: blue-claw males (final stage having high mating activity), orange-claw males (transitional stage showing rapid somatic growth), and small males (primary stage showing sneak copulation). This morphotypic differentiation is considered to be controlled by androgenic gland hormone, which is probably a peptide hormone. However, its physiological roles are not fully understood. In the present study, we examined the correlation of androgenic gland cell structure to spermatogenic activity and morphotypic differentiation histologically in M. rosenbergii. spermatogenic activity showed close correlation to the molt cycle in orange-claw males and small males. spermatogonia increased in number in the late premolt stage, becoming spermatocytes in the postmolt stage, and spermatocytes differentiated into spermatozoa in the intermolt and early premolt stages. Ultrastructure of the androgenic gland was additionally compared among the molt stages, but, distinct histological changes were not observed in relation to spermatogenesis during the molt cycle. On the other hand, among the three morphotypes, the androgenic gland was largest in the blue-claw males, containing developed rough endoplasmic reticulum in the cytoplasm. These results suggest that, during spermatogenesis which is related to the molt cycle, the androgenic gland hormone is at rather constant levels and plays a role in maintaining spermatogenesis rather than directly regulating the onset of a specific spermatogenesis stage and that, during the morphotypic differentiation, the androgenic gland is most active in the blue-claw males and plays a role in regulating the observed high mating activity in M. rosenbergii.
Analysis of Variance↗
Neonatal focal denervation of the rat olfactory bulb alters cell structure and survival: a Golgi, Nissl and confocal study.
Contact between sensory axons and their targets is critical for the development and maintenance of normal neural circuits. Previous work indicates that the removal of afferent contact to the olfactory bulb affects bulb organization, neurophenotypic expression, and cell survival. The studies also suggested changes to the structure of individual cell types. The current work examines the effects of denervation on the morphology of mitral/tufted, periglomerular, and granule cells. Focal denervation drastically changed mitral/tufted cell structure but had only subtle effects on periglomerular and granule cells. Denervated mitral/tufted cells lacked apical tufts and, in most cases, a primary dendrite. In addition, the denervated cells had more secondary processes whose orientation with respect to the bulb surface was altered. Our results suggest that contact between olfactory axons and the bulb is necessary for cell maintenance and may be critical for the ability of mitral/tufted cells to achieve adult morphology
Animals↗
Biochemical effects of pure isomers of hexachlorobiphenyl: fatty livers and cell structure.
The effects of a single oral dose (50 mg/kg body wt.) of 3,4,5,3',4',5'-hexachlorobiphenyl (HCB), 2,4,5,2',4',5'-HCB or 2,3,5,2',3',5'-HCB for a period of 72 h have been studied in the male rat. Only 3,4,5,3',4',5'-HCB caused necrosis of thymocytes. 3,4,5,3',4',5'-HCB caused marked pathological changes in the liver with less marked effects being caused by 2,4,5,2',4',5'-HCB and 2,3,5,2',3',5'-HCB. Total lipid content was increased by all the isomers studied, but 3,4,5,3',4',5'-HCB had more pronounced effect on total lipid content. Lipid accumulation was pericentral in the livers obtained from rats treated with 3,4,5,3',4',5'-HCB, but midzonal in the liver obtained from the rats treated with the other two isomers. Analysis of various lipid fractions showed that triacylglycerols were increased seven-fold only by 3,4,5,3',4',5'-HCB, while phospholipids were increased slightly by 2,4,5,2',4',5'-HCB or 2,3,5,2',3',5'-HCB. Only 3,4,5,3',4',5'-HCB increased the level of total and esterified cholesterol. These results show that the fatty livers caused by 3,4,5,3',4',5'-HCB were qualitatively and quantitatively different from those caused by the other two isomers at the same dose. For the first time a hexachlorobiphenyl unchlorinated in the para position, 2,3,5,2',3',5'-HCB has been shown to be a specific inducer of cytochrome P-450. The effects of 2,3,5,2',3',5'-HCB on cell structure and phospholipid content were quantitatively similar to those caused by 2,4,5,2',4',5'-HCB. Thus, chlorination at para (4,4') positions in chlorobiphenyls is not necessarily required for biological activity. It is hypothesized that net stereoelectronic properties of the isomers or resistance to metabolism may be the underlying factor in determining structure-activity relationships.
Animals↗
The neuroscience of Helmholtz and the theories of Johannes Müller. Part 1: Nerve cell structure, vitalism, and the nerve impulse.
Hermann Helmholtz made monumental contributions to the neural sciences in the second half of the nineteenth century. Among his earliest achievements were experiments that challenged vitalism, microscopic studies on the structure of the nerve cell and its processes, and the first reasonable estimates of the speed of nerve transmission based on physiological experiments. In this, the first of a two-part article, we review Helmholtz's early contributions in biographical context and with reference to Johannes Müller's own thoughts. We reveal how Johannes Müller, considered by many to be the greatest physiologist of the first half of the nineteenth century, helped to launch and shape Helmholtz's career. We also show that Helmholtz was only willing to accept some of his mentor's theories, even though he had great admiration for Müller. The point will be made that Helmholtz owed a great debt to Müller, but even from his student days in Berlin he was an independent thinker with his own agenda, and never his strict disciple.
Germany↗
Effects of weightlessness on photosynthesizing cells structure of plant.
It was established early that the signs of accelerated aging of both plant leaves and of moss chloronema were observed in seedlings of high plants and in Funaria hygrometrica protonema under long term growing under weightlessness. It was observed the structure changing of photosynthesizing cells in Arabidopsis thaliana, Epidendrum radicans and Pisum sativum leaves. Authors found out the extension and vesiculation of thylakoids between chloroplast granas. They observed thylakoids partly destroying under 96 and 110 days microgravity influence. But some questions are still opened: 1. Are these changes consequence of accelerated differentiation and aging photosynthesizing cells? 2. Do the definite changes appear in photosynthesizing cells during short-term microgravity influence? Therefore the study of mesophyll cells ultrastructure of leaves that finished growth by tension in microgravity was the idea of our experiment.
Adenosine Triphosphate↗
O6-Methylguanine-DNA methyltransferase of human lymphoid cells: structural and kinetic properties and absence in repair-deficient cells.
Human lymphoid cell lines contain a DNA repair enzyme which removes the mutagenic alkylation lesion O6-methylguanine from DNA. The enzyme transfers the methyl group to a protein cysteine residue, generating S-methylcysteine, and is inactivated as a consequence of the reaction. Apparently the methylated enzyme represents a dead-end complex. The transfer reaction is very rapid and is completed in less than 1 min at 37 degrees, but methyl group transfer from single-stranded DNA or heavily damaged DNA is less efficient. The active methyltransferase and the methylated protein both have molecular weights of 21,000 to 22,000, as determined by gel filtration. Lymphoid cell lines proficient in repair of O6-methylguanine in vivo, Mex+, contain 10,000 to 25,000 molecules of the methyltransferase per cell. In contrast, repair-deficient cell lines, Mex-, do not contain detectable amounts of the enzyme. The latter point was verified by applying a partial purification procedure for the enzyme to cell-free extracts from two Mex- cell lines.
Burkitt Lymphoma↗
Dictyostelium discoideum cells lacking the 34,000-dalton actin-binding protein can grow, locomote, and develop, but exhibit defects in regulation of cell structure and movement: a case of partial redundancy.
Cells lacking the Dictyostelium 34,000-D actin-bundling protein, a calcium-regulated actin cross-linking protein, were created to probe the function of this polypeptide in living cells. Gene replacement vectors were constructed by inserting either the UMP synthase or hygromycin resistance cassette into cloned 4-kb genomic DNA containing sequences encoding the 34-kD protein. After transformation and growth under appropriate selection, cells lacking the protein were analyzed by PCR analyses on genomic DNA, Northern blotting, and Western blotting. Cells lacking the 34-kD protein were obtained in strains derived from AX2 and AX3. Growth, pinocytosis, morphogenesis, and expression of developmentally regulated genes is normal in cells lacking the 34-kD protein. In chemotaxis studies, 34-kD- cells were able to locomote and orient normally, but showed an increased persistence of motility. The 34-kD- cells also lost bits of cytoplasm during locomotion. The 34-kD- cells exhibited either an excessive number of long and branched filopodia, or a decrease in filopodial length and an increase in the total number of filopodia per cell depending on the strain. Reexpression of the 34-kD protein in the AX2-derived strain led to a "rescue" of the defect in the persistence of motility and of the excess numbers of long and branched filopodia, demonstrating that these defects result from the absence of the 34-kD protein. We explain the results through a model of partial functional redundancy. Numerous other actin cross-linking proteins in Dictyostelium may be able to substitute for some functions of the 34-kD protein in the 34-kD cells. The observed phenotype is presumed to result from functions that cannot be adequately supplanted by a substitution of another actin cross-linking protein. We conclude that the 34-kD actin-bundling protein is not essential for growth, but plays an important role in dynamic control of cell shape and cytoplasmic structure.
Actins↗
In vitro models of differentiated Sertoli cell structure and function.
Primary cultures of Sertoli cells maintained in conventional cultures on plastic culture vessels do not retain many of the structural and functional properties of their in vivo counterparts. Sertoli cell phenotype is better maintained by incorporating certain environmental parameters, intrinsic to the testis, into the Sertoli cell culture system. These environmental parameters include a) high cell density, b) a unique extracellular matrix, c) a semipermeable support between the basal plasma membrane of the cells and blood-derived nutrients in the interstitium, d) chemically distinct microenvironments at the apical and basal surfaces of the cells, and e) cell-to-cell interactions among Sertoli cells and other testicular cell types. Using three variations of Sertoli cell culture we have demonstrated the importance of each of these environmental parameters in obtaining a better Sertoli cell culture model.
Animals↗
Are intermediate filaments of vertebrate smooth muscle cells and tonofilaments of epithelial cells identical cell structures?
In epithelial and smooth muscle cells of the urinary bladder of the frog, a class of filaments exists which is partly disintegrated by glycerol treatment and very resistant to potassium solutions of high ionic strength.
Animals↗
The early changes of parietal cell structure in the course of secretory activity in the rat.
The fine structure of the rat parietal cell was studied, both at rest and after stimulation by refeeding or insulin administration. Experiments on fixation procedures showed that whenever the fixative contained sucrose at a concentration higher than 0.2 M, the system of cytoplasmic membranes was clearly tubular in arrangement, whereas the omission of sucrose in the fixative usually resulted in a vesicular structure. The study with the high-voltage electron microscope of thick sections prepared by conventional techniques or by impregnation with zinc iodide-osmium (ZIO) revealed that the tubules are grouped into fascicles, and that these form a feltwork that is especially thick toward the cell apex. The development of the secretory canaliculus after stimulation appears to take place by an in situ remodeling of the cytoplasmic domain occupied by the tubular system. Cells examined after short periods of stimulation (5-15 min) showed images of the tubular system and of the canalicular structure which differed both from the nonstimulated and from the fully active (30-45 min of stimulation) cell. These features include the formation of wide cisternae and of pericanalicular cytoplasmic trabeculae or laminae, whose fine structure bears close resemblance to that of the intracanalicular processes in the same cells. These images can be ordered into a hypothetical sequence which is proposed as a model to explain the transformation of the tubular system and intervening cytoplasmic matrix into secretory canaliculus.
Animals↗
Two- and three-dimensional cell structures govern epidermal growth factor survival function in human bladder carcinoma cell lines.
Human bladder carcinomas often express high levels of the epidermal growth factor (EGF) receptor. In three human bladder carcinoma cell lines (OBR, T24, and 647V), we show that two EGF receptor ligands, namely EGF and transforming growth factor alpha, enhanced the apoptosis due to serum starvation on cells cultured as monolayers. Conversely, EGF and transforming growth factor alpha prevented apoptosis when the same serum-starved cells were cultured as three-dimensional spheroids. Both stimulation and inhibition of apoptosis by EGF were associated with p21 WAF1/CIP1 overexpression. In 647V spheroids, EGF protection against radiation-induced apoptosis was negated by genistein and tyrphostin AG1478, suggesting that blockade of the EGF signal transduction in patients with bladder cancer may improve the radiotherapy efficacy.
Apoptosis↗
Inorganic thiophosphate effects on chromaffin cell structure and function.
The effect was determined of replacing medium inorganic phosphate with thiophosphate on the structure and function of cultured bovine chromaffin cells. Cell cultures were incubated in normal medium containing fetal bovine serum, phosphate free medium or similar medium supplemented with inorganic phosphate or thiophosphate. In contrast to the other media, cells cultured with thiophosphate medium for 3-4 days showed seriously compromised structure and functions. The cells lost 75% of their catecholamine content and their ability to secrete remaining catecholamines in response to nicotine stimulation. Radiolabelled thiophosphate was rapidly taken up by the cells and, in long-term experiments, was incorporated largely into a 97-121 kDa protein band on SDS-PAGE. Additional minor bands were found to a lesser, variable extent. Transmission electron micrographs of cells treated with thiophosphate showed extensive depletion of chromaffin vesicles and disruption of mitochondria, suggesting that the functional damage noted with these cells could be associated with damage to mitochondria. Analysis of general cell metabolic activity by conversion of the dye (3-[3,4-dimethylthiazol-2-yl]-3,5-diphenyltetrazolium bromide) to its formazan derivative indicated increased metabolic activity at early stages of exposure to thiophosphate followed by a decline with continued exposure, supporting the argument for an overall depression of cell metabolism. Uptake of the dye neutral red, which is avidly accumulated by chromaffin cells, was also reduced for cells exposed to thiophosphate. The data suggest that thiophosphate enters chromaffin cells and disrupts energy dependent cell functions, including catecholamine storage and secretion.
Animals↗
[Interaction of lactate dehydrogenase with structural cell components: possible physiological significance].
Reversible binding of cytoplasmic enzymes to structural elements of the cell is one of mechanisms of in vitro regulation of enzyme properties. The results on lactate dehydrogenase interactions with myofibrillar proteins and membranes and the changes in enzyme properties induced by these interactions (modification of kinetic parameters and stability) are analyzed. A hypothesis is proposed concerning the functional role of reversible lactate dehydrogenase interactions with structural components of the cell during glycolysis activation.
Adsorption↗