bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cytoplasmic, nuclear, membrane-bound and secreted [35S]methionine-labelled polypeptide pattern in differentiating fibroblast stem cells in vitro
Authors: Francz P. I. , Bayreuther K. , Rodemann H. P. 
Published: April 2021

ABSTRACT
Methods for the selective enrichment of various subpopulations of the human skin fibroblast cell line HH-8 have been developed. These methods permit the selection of homogeneous populations of the three mitotic fibroblast cell types MF I, II and III, and the four postmitotic cell types PMFIV, V, VI and VII. These seven cell types exhibit differentiation-dependent and cell-type-specific patterns of [35S]methionine-labelled polypeptides in total soluble cytoplasmic and nuclear proteins, also in membrane-bound proteins, and in secreted proteins. In the differentiation sequence MF II - MF III - PMF IV - PMF V - PMF VI 14 cell-type-specific marker proteins have been found in the cytoplasmic and nuclear fraction, also 24 cell-type-specific marker proteins have been found in the membranebound protein fraction, and 11 cell-type-specific marker proteins in the secreted protein fraction. Markers in spontaneously arising and experimentally selected or induced populations of a single fibroblast cell type were found to be identical.
NCL-SG3: A human eccrine sweat gland cell line that retains the capacity for transepithelial ion transport
Authors: Lee Catherine M. , Dessi John 
Published: April 2021

ABSTRACT
An ion-transporting human epithelial cell line, NCL-SG3, has been established by simian virus 40 (SV40) infection of primary cultures from eccrine sweat glands.
The line has been passaged 38 times (over 100 population doublings), has an aneuploid karyotype but has not undergone any ‘crisis’. The cells have retained epithelial morphology and expression of cytokeratin, the intermediate filament characteristic of epithelial cells. Approximately 85% of the population shows at least weak co-expression of vimentin, an intermediate filament associated with mesenchymal and some other non-epithelial cell types in vivo. In addition, SV40 large T-antigen is present, in a predominantly nuclear localization.
Electrically resistant cell sheets are formed on dialysis tubing and cellulose-ester permeable supports. Electrogenic ion transport can be stimulated by the β-adrenergic agonist isoproterenol (10−6M) and by lysylbradykinin (10−7M) but not by the cholinergic agonist carbachol at 10 −6M.
The kinetics of cell-substratum detachment mediated by trypsin: A comparison of normal and duchenne fibroblasts
Authors: Simon L. V. , Pizzey J. A. , Jones G. E. 
Published: April 2021

ABSTRACT
In previous studies of cell-cell and cell-substratum adhesion, we have identified differences in the behaviour between human skin fibroblasts cultured from normal individuals and patients with Duchenne muscular dystrophy (DMD). In these studies, monolayer cultures were dissociated by trypsinization. and no detectable difference was noted in the efficiency of cell dissociation between normal and DMD fibroblast cultures. However, a detailed study by Kent has suggested that Duchenne fibroblasts exhibit increased sensitivity to trypsin. We have re-investigated this finding using an assay that directly measures the number of cells remaining attached to a substratum following trypsinization. In a series of experiments using cultures derived from five normal and five DMD individuals, we can detect no significant difference in the trypsin-induced detachment rates between normal and DMD skin fibroblasts. This observation applies to both growth-phase and stationary-phase cell cultures. This inconsistency with previously reported data on the trypsin-sensitivity of DMD cells is considered in terms of the different assays used and the effects of trypsin on cell-cell and cell-substratum adhesion. The relationship between abnormalities in the behaviour of DMD cells and the localization and primary structure of the DMD gene product are also discussed.
Ultrastructural changes accompany inhibition of proteoglycan synthesis in chondrocytes by cyclofenil diphenol
Authors: Lancaster Carole A. , Fryer Patricia R. , Griffiths Stephen , Mason Roger M. 
Published: April 2021

ABSTRACT
Cyclofenil diphenol, a weak non-steroidal oestrogen, profoundly inhibits [35S] proteoglycan synthesis in cultures of Swarm chondrosarcoma chondrocytes under conditions in which protein synthesis is only marginally reduced. In the present experiments it was shown that after a 40-min treatment with Cyclofenil diphenol (90 μg ml1) most of the normally abundant Golgi stacks in these cells disappeared and after 60 min they were absent. After 2 – 3 h treatment the cisternae of the endoplasmic reticulum (ER) were grossly distended and transformed into large ribosome-studded vesicles containing flocculent and filamentous material. These changes were dependent on the concentration of Cyclofenil and were fully reversible within 21 h of withdrawing the drug.
The ultrastructural changes differed in some aspects if protein synthesis was blocked with cycloheximide for 15 min or 180 min before and during treatment with Cyclofenil. The Golgi disappeared but the ER cisternae, though distended, formed a continuous network and swollen ribosome-studded vesicles did not develop. However, non-membrane-bounded structures containing lipid droplets and material of low electron density developed in the cytoplasm under these conditions.
The ultrastructural changes induced by Cyclofenil differ from those induced by monensin and diethylcarbamazine, suggesting that the drug acts at a different point in the secretory pathway for macromolecules.
Identification of a nucleic acid-regulated cyclic gmp-binding activity in Dictyostelium discoideum
Authors: Parissenti A. M. , Coukell M. B. 
Published: April 2021

ABSTRACT
Using ion-exchange chromatography, we have identified and isolated two forms of a cyclic GMP-specific binding activity in filter-broken cell extracts of Dictyostelium discoideum. Upon addition of excess cold ligand, one form (S-type) released bound 3H-labelled cyclic GMP very slowly (t½ ≈ 68 min), while the other form (F-type) released the cyclic GMP in &lt;1 min. After photoaffinity labelling with 32P-labelled cyclic GMP, both forms revealed a major 160×103Mr band (and a few bands of lower molecular weight) on autoradiograms of sodium dodecyl sulphate-polyacrylamide gels. Addition of 500mM-NaCl to S-type activity converted the activity to a fast-dissociating form indistinguishable from F-type, and this conversion was reversed by dialysis. Salt treatment or dialysis had no appreciable effect on the association/dissociation kinetics of F-type activity. When crude S-type activity was heated (to destroy cyclic GMP binding) and then added to F-type activity, the latter activity acquired slow-dissociating properties identical to S-type. This result suggested that the cells possess a ‘factor’ that can dramatically alter the binding properties of this cyclic GMP-binding protein. Crude preparations of this factor were unaffected by boiling or proteases, but were sensitive to RNase A. Further studies revealed that nucleic acids (in particular, DNA) could effectively mimic the factor in its ability to modulate the binding kinetics of the cyclic GMP-binding activity.
Three-dimensional chromosome arrangement of Crepis capillaris in mitotic prophase and anaphase as studied by confocal scanning laser microscopy
Authors: Oud J. L. , Mans A. , Brakenhoff G. J. , Van Der Voort H. T. M. , Van Spronsen E. A. , Nanninga N. 
Published: April 2021

ABSTRACT
To estimate the extent of ordering of chromosomes, confocal scanning laser microscopy was used to make three-dimensional images from optical sections. For Crepis capillaris, which has 2n = 6 easily recognizable chromosomes, a statistically significant sample of 75 Feulgen-stained root tip anaphases was analysed. A comparison of the observed chromosome ordering and the expected random distribution showed a significant surplus of one of the arrangements with a juxtaposition of the two chromosomes with a nucleolus organizer region. Two of the arrangements with these chromosomes in opposite positions were never observed in our material. Another analysis of 30 mithramycin A-stained prophases and 30 meta- and anaphases showed partly different patterns of non-random chromosome distribution in the two stages of mitosis. A preference for an association of the homologues was observed for all pairs of chromosomes in prophase cells, whereas in meta- and anaphase the association only persisted for the nucleolus organizer chromosomes. This indicates that there may be some relocation of the chromosome positions during the transition from prophase to metaphase. In meta- and anaphase one of the arrangements with juxtaposed NOR chromosomes was preferred, i.e. the ordering in which chromosomes 1 and 3 occupied alternate positions. Probably, the nucleolus is an important factor in producing a non-random distribution, but there could be other factors that influence chromosome ordering as well. A comparison of the anaphase chromosome ordering in C. capillaris plants from very different localities, indicated that the observed non-random distribution was independent of the origin of the material. Existing models of chromosome disposition are not sufficient to explain the observed non-random chromosome ordering in C. capillaris.
Microinterferometry of the movement of dry matter in fibroblasts
Authors: Brown A. F. , Dunn G. A. 
Published: April 2021

ABSTRACT
We describe the use of interferometric microscopy coupled with a novel application of Sénarmont compensation for detecting and quantifying the distribution of dry matter in cultured cells. In conjunction with video techniques and digital image processing, a two-dimensional, calibrated map of the dry mass distribution in an isolated cell can be obtained and digitally recorded. We have called the technique Digitally Recorded Interferometric Microscopy with Analyser Shift (DRIMAS). The method greatly facilitates the automatic recognition of cells by computer. Recorded time-lapse sequences can be used to establish a database of the growth and motility of specific cells in given experimental conditions.
Databases of this type can be analysed to reveal the patterns of growth and locomotory behaviour of individual cells. We describe a systematic method of obtaining parameters of cell size, shape, spreading, intracellular motility and translocation. Autocorrelations and cross-correlations between these parameters can be detected and quantified using time series analysis, revealing potential cause/effect relationships in the mechanisms of growth and motility.
Besides characterizing the overall pattern of cell behaviour, these data can also yield information about the instantaneous pattern of intracellular motility. We describe the use of finite element analysis to reveal the dynamics of the intracellular transport of dry matter. This yields the pattern of the minimum flow of dry matter required to account for the changes in its distribution. Most of this flux is not associated with the movement of visible structures and possibly represents the transport of dissociated components of the cytoskeleton. In chick heart fibroblasts, surprisingly high velocities of nearly 2·0 μm s−1 were detected during the period of increased motility following tail detachment. The total kinetic energy associated with the dry mass flux is a single parameter, which characterizes the instantaneous motility of the cell. We found that the kinetic energy of intracellular motility can be several hundred times greater than the kinetic energy of translocation. Kinetic energy may prove to be a very informative single measure of intracellular motility for assessing the effects of malignant transformation, genetic manipulations, and other experimental treatments on the locomotory machinery of the cell.
Surface views of spermatozoa as revealed by fracture-flip
Authors: Forsman Catarina Andersson , Silva Pedro Pinto Da 
Published: April 2021

ABSTRACT
We have used fracture-flip to produce new, macromolecular-resolution images of the surface of boar spermatozoa. Over the head, acrosomal and postacrosomal regions display sharply demarcated, subtly different surface textures. The rim is particle-poor, as well as a region above the oblique cords over the posterior ring. The tail shows two morphologically distinct domains: (1) the principal piece is covered by a high density of parallel-helical strands and a high density of large globular particles; (2) the midpiece and the neck are covered by smaller particles with apparent random distribution. Rectangular surface specializations frequently seen near the annulus display a waffle-like texture. With the notable exception of the parallelhelical strands of the principal piece the fractureflip images of the boar spermatozoon can be directly related to the freeze-fracture morphology of its plasma membrane.
Quantitative analysis of membrane and secretory protein processing and intracellular transport
Authors: Noe Dennis A. , Delenick Joann C. 
Published: April 2021

ABSTRACT
Quantitative experimental data from studies of intracellular processing and transport of secretory and membrane proteins are only rarely evaluated using kinetic modelling. Instead, the analysis of such data is usually limited to calculating either the apparent half-life or the transit time. Neither of these parameters accurately measures rates of cellular processing or transport. This paper describes a formal approach for the calculation of rate constants, half-lives and lag times for single and sequential processing and transport steps. Generalized kinetic models are presented that can be used to analyse data from both pulse-chase and continuous incubation experiments with labelled amino acids or sugars. The results from a number of published studies are reanalysed using the models to demonstrate the usefulness of kinetic modelling in the routine analysis of experimental data.
Collagenase secretion accompanying changes in cell shape occurs only in the presence of a biologically active cytokine
Authors: Kuter Irene , Johnson-Wintj Barbara , Beaupre Nancy , Gross Jerome 
Published: April 2021

ABSTRACT
We have investigated the relationship between collagenase production, cell shape and stimulatory factors in cell culture. In a homogeneous culture of primary rabbit corneal stromal cells, shape change induced by a variety of agents was not effective in stimulating collagenase secretion. Only in the presence of a biologically active cytokine or phorbol myristate acetate was a correlation seen between changes in cell shape (induced by a second agent) and collagenase secretion by these primary cells. Cell shape changes were not, however, necessary for collagenase secretion, since certain concentrations of endotoxin or lactalbumin hydrolysate effected secretion of the enzyme in the absence of morphological changes. With passaged cells or mixed cell cultures, where cell shape change did correlate with collagenase secretion without the addition of an exogenous agent, the production of an effective cytokine (autocrine or paracrine) was demonstrated. Thus cell shape change seems to be neither universally necessary nor sufficient for the stimulation of collagenase secretion. It is proposed that the function of cytokines may be more immediately related to gene expression in this system than is change in the shape of the cell. The hypothesis is presented that cell shape changes may render the target cells receptive to cytokines, perhaps by replacing the need for a natural cytokine cofactor. It is also demonstrated here that the use of passaged cells, mixed cell cultures containing endogenous cytokine-secreting cells or tissue culture additives can profoundly affect the interpretation of the effect of various agents on collagenase secretion, and may lead to observations that are not directly relevant to cell function in vivo.
Gelatinase (type iv collagenase) immunolocalization in cells and tissues: Use of an antiserum to rabbit bone gelatinase that identifies high and low M
r forms
Authors: Murphy G. , Hembry R. M. , McGarrity A. M. , Reynolds J. J. , Henderson B. 
Published: April 2021

ABSTRACT
An antiserum was raised to rabbit bone gelatinase (type IV collagenase). It was shown by immunoblotting to detect both the low Mr (72000) enzyme produced by connective tissue cells from rabbit, pig, human and mouse, as well as the high Mr (94000–97000) enzymes secreted by macrophages and polymorphonuclear leucocytes from these species, and by rabbit chondrocytes and endothelial cells. Crossed immunoblotting, antibody inhibition and deglycosylation studies indicated that the high and low Afr forms of gelatinase are immunologically distinct gene products, although their substrate specificity profiles are identical.
The anti-gelatinase antiserum was used to immunolocalize the enzyme. Gelatinase was most efficiently detected in rabbit monocytes and connective tissue cells, but cells derived from the human and pig gave poor immunostaining, although mouse gelatinase stained well. The anti-gelatinase antiserum stained cells of the synovial tissue of rabbits at 14 days after induction of an antigen-induced arthritis, demonstrating its usefulness as a tool to assess the role of this enzyme in degradative events.
Invasion of a basement membrane matrix by chick embryo primitive streak cells in vitro
Authors: Sanders E. J. , Prasad S. 
Published: April 2021

ABSTRACT
At the time of gastrulation in the chick embryo the upper epiblast layer penetrates its own basement membrane at the primitive streak so that its cells may invade the underlying tissue space. In so forming the primary mesoderm, the cells undergo a concomitant epithelial-to-mesenchymal transformation. In this study, epiblast tissue has been explanted onto a basement membrane gel in order to examine its invasive potential. Fully ingressed primary mesoderm cells were able to penetrate the gel as individual cells, during the course of which the texture of the gel was disrupted. By contrast, epiblast tissue taken from the immediate vicinity of the primitive streak penetrated the gel, but only as a coherent tongue of cells and without gel disruption. These tongues of cells did not undergo the epithelial-to-mesenchymal transformation, and consequently spread as a epithelial sheet when replated on glass. Thus, the absence of gel disruption correlated with the failure of transformation, suggesting that these two events may be linked and that they may require in situ cell interactions for their manifestation. Tissue from the lateral epiblast failed to penetrate the gel. Instead, this tissue either spread on the gel surface or rounded up into a hollow sphere with the basal surface of the cells innermost. In the former case, despite the cell spreading, no lamina densa was organized beneath the sheet, but in the latter case polarity reversal occurred with the formation of a new lamina densa at the cell-gel interface. These results demonstrate that epiblast cells from the primitive streak region tend to show some inherent invasiveness, while more lateral cells do not. However, although this in vitro system may model such embryonic invasive potential, it cannot elicit a prompt epithelial-to-mesenchymal transformation.
Colour genes, oncogenes and melanocyte differentiation
Authors: Bennett Dorothy C. 
Published: April 2021

ABSTRACT
Pigmentation has long been a favourite and easily used marker in the genetics of diverse organisms. Mammalian integumental pigments are melanins, synthesized by melanocytes in the epidermis and hair bulbs. Our understanding of mammalian pigmentation genes has been advanced significantly in the last few years (Hearing and Jiménez, 1989), partly by the advent of methods for the culture and immortalization of melanocytes. In cultured melanocytes, homozygous recessive germline mutations can be visibly expressed, complemented or even revert spontaneously, as will be discussed. In the mouse there are over 130 mutations that affect coat colour, mapping to well over 50 loci (Silvers, 1979). For the sake of brevity, most of this commentary will be concerned with the recent molecular characterization of mutations at just four of these loci, two of which encode developmentally controlled, melanocyte-specific products while the other two play a part in melanocyte development.
On the mechanism of induction of dna synthesis in cultured arterial smooth muscle cells by leukotrienes: Possible role of prostaglandin endoperoxide synthase products and platelet-derived growth factor
Authors: Palmberg Lena , Åke Lindgren Jan , Thyberg Johan , Claesson Hans-Erik 
Published: April 2021

ABSTRACT
The induction of DNA replication in rat aortic smooth muscle cells (SMCs) by leukotrienes (LTs) was studied in order to elucidate the mechanisms of action in further detail. The effect of LTB4 was blocked by the prostaglandin (PG) synthesis inhibitor indomethacin and the effects of LTC4 and LTD4 were blocked by the cysteinyl-containing leukotriene receptor antagonists FPL 55712 and ICI 198615. These observations suggest that LTB4 and the cysteinyl-containing leukotrienes act via distinct receptors and point to a role for prostaglandin endoperoxide synthase products in bringing about the effect of LTB4. Radioimmunological determinations and analyses of [3H]arachidonic acid metabolism showed that the SMCs were able to synthesize PGI2 (measured as the stable metabolite 6-keto-PGFlα), PGE2, PGF2α, and 15(S)hydroxy-eico-satetraenoic acid (15(S)HETE). Moreover, picomolar concentrations of arachidonic acid, PGI2, PGE2, PGF2β and 15(S)HETE induced DNA replication in the SMCs under serum-free conditions, whereas linoleic acid, 6-keto-PGFlα and 5(S)HETE were inactive in this respect Analysis of conditioned media for mitogenic activity (with or without antibodies against platelet-derived growth factor, PDGF) and for the presence of material competing with radioiodinated PDGF for binding to specific cell surface receptors indicated that LTB4 stimulated release of PDGF or a PDGF-like molecule from the cells. These findings suggest that the growth-promoting effect of LTB4 is mediated via a prostaglandin endoperoxide synthase product and/or PDGF produced by the cells themselves.
Rotating the plane of imposed vibration can rotate the plane of flagellar beating in sea-urchin sperm without twisting the axoneme
Authors: Shingyoji Chikako , Katada Jun , Takahashi Keiichi , Gibbons I. R. 
Published: April 2021

ABSTRACT
When the head of a sea-urchin sperm is held in the tip of a micropipette and vibrated laterally, the flagellum beats in phase with the imposed vibration. Rotation of the plane of pipette vibration around the head axis induces a corresponding rotation of the plane of beating, in both live and reactivated sperm. Detailed analysis of the waveforms occurring at different stages of this rotation shows that the characteristic asymmetry of the flagellar bending waves rotates along with the plane of beat. The positions of small polystyrene beads attached as markers on the axonemes of demembranated sperm flagella appear unaffected by the rotation of the beat plane and asymmetry. The imposed rotation of the waveform is thus the result of a rotation of the coordinated pattern of sliding among the doublet tubules of the axoneme, and is not accompanied by a twisting of the whole axonemal structure. These data indicate that neither the plane of flagellar beat nor the direction of beat asymmetry is tightly dependent upon a structural or chemical specialization of particular members of the nine outer doublet microtubules, but that both are the result of some regulatory structure that can be forced to rotate relative to the outer structure of the axoneme.