bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural and biochemical aspects of liver cell nuclear organization in normal and scalded rats
Authors: Śevaljević Ljiljana , Petrović Miodrag , Poznanović Goran , Śkaro Andjelija , Pantelić Dragoljub 
Published: April 2021

ABSTRACT
The response of rat liver nuclei to thermal injury was studied at the ultrastructural and biochemical levels using nuclei isolated in the presence of either Mg2+ or polyamines and metal chelators.
The extent of chromatin condensation, as revealed by electron microscopy, increased in the order: nuclei in situ, Mg-stabilized nuclei, polyamine-stabilized nuclei. In addition, we observed that thermal injury caused an increase in the number of nuclear pores, an enlargement of nucleoli and an accumulation of ribonucleoprotein material. Along with this, greater amounts of protein, DNA and RNA were retained in nuclei from scalded rats.
The salt-resistant residue from Mg-stabilized nuclei was a spherical proteinaceous structure of the nuclear matrix, whereas that of the polyamine-stabilized nuclei was amorphous and deprived of three major constituents of the spherical matrix, the 60 –70 × 103Mr lamina proteins. However, exposure of the polyamine-stabilized nuclei to Ca2+ and Mg24- rendered the 60 –70 × 103Mr proteins salt-insoluble and thus enabled the extraction of a spherical residual nuclear structure. This structure was highly enriched in DNA, RNA and non-histone proteins and, hence, more like dehis-tonized nuclei than the minimal residual nuclear structure. It retained 70% of DNA in the controls but virtually all the DNA in scalded rats. This difference was interpreted to reflect activation-related changes in chromatin organization.
Activatable esterase activity of murine natural killer cell-yac tumour cell conjugates
Authors: Petty Howard R. , Hermann William , Dereski William , Frey Tom , Mcconnell Harden M. 
Published: April 2021

ABSTRACT
Natural killer (NK) cells have been obtained from mouse spleens and grown in vitro. These cells: (1) retained cytotoxicity against YAC targets; and (2) were homogeneous as judged by morphology and surface markers. The a-naphthol acetate esterases (ANAE) and diisopropyl-fluorophosphate (DFP)-binding proteins of NK cells, YAC cells and NK-YAC conjugates have been examined. Ultrastructural cytochemistry indicates that NK cells have two types of ANAE: an enzyme primarily associated with the granule externum and an activatable ANAE associated with the granule internum. Both of these activities are inhibited by DFP. The activatable ANAE appears during incubation of NK cells with YAC cells.
DFP-binding proteins were examined by sodium dodecyl sulphate/polyacrylamide gel electrophoresis and autofluorography. NK cells and YAC cells have major DFP-binding proteins of 35 × 103 and 20 × 103Mr, respectively. NK-YAC conjugates had a new band at 55 × 103MrThis new protein may be identical to the activatable ANAE described above. Our studies provide evidence for an NK cell esterase that becomes activated when incubated in the presence of tumour cells. This esterase may be related to the cytolytic mechanism.
Cell type specific electrophoretic polypeptide profiles of cultured bovine cells
Authors: Lincoln David W. , Braunschweiger II, Karen I. , Braunschweiger Walter R. , Smith James R. 
Published: April 2021

ABSTRACT
The polypeptide profiles of bovine vascular endothelial cells (from pulmonary artery and descending aorta), smooth muscle cells (from pulmonary artery) and fibroblast cells (from skin and lung) were examined by high-resolution two-dimensional polyacrylamide gel electrophoretic techniques. A set of polypeptides (molecular weights between 43 × 103 and 47 × 103 and pl values from 6·0—4·8, respectively) exhibited patterns that were unique to the three cell types. In the case of smooth muscle cells, these polypeptides exhibited cell-density-dependent expression. These results allow for identification of the three cell types on the basis of their highly specific polypeptide signatures.
Human serotonectin: A blood glycoprotein that binds serotonin and is associated with platelets and white blood cells
Authors: Tamir H. , Payette R. F. , Huang Y. L. , Liu K. P. , Gershon M. D. 
Published: April 2021

ABSTRACT
A glycoprotein that circulates in blood, binds to the surface of platelets, and also binds serotonin with high avidity and specificity, has previously been found in rats. This glycoprotein has been called serotonectin. We now report the purification and characterization of a similar circulating glycoprotein in human blood that we propose be called human serotonectin, to distinguish it from the rat protein. Human serotonectin binds serotonin with high affinity (Kd1=36nM; Kd2= 1·1 μM). Monospecific antisera were raised in rabbits to purified human serotonectin. These antibodies were used to locate human serotonectin immunocytochemically, for quantitative estimation of the glycoprotein, and for rapid preparation of material purified by affinity chromatography. Evidence was obtained that indicated that human serotonectin circulates in plasma and also binds to the surfaces of white blood cells and platelets but not to red blood cells. In bone marrow it is found on megakaryocytes and on developing white cells of the eosinophil line. The protein can be completely removed by washing with isotonic sucrose or salt solutions from the surfaces of white cells but similar treatment only partially (63% sucrose wash/73% salt wash) removes human serotonectin from platelets. Antibodies to human serotonectin antagonize the uptake of serotonin by platelets but do not inhibit platelet aggregation. These data show that humans, like rats, have a circulating serotonin-binding glycoprotein that is also present as a peripheral membrane protein on platelets. The human also differs from the rat serotonectin in binding to white cells. The material may function in platelet serotonin uptake in both humans and rats; however, its function, if any, with respect to white cells is obscure.
Skin fibroblasts obtained from cancer patients display foetal-like migratory behaviour on collagen gels
Authors: Schor S. L. , Schor A. M. , Durning P. , Rushton G. 
Published: April 2021

ABSTRACT
When plated on the surface of collagen gel substrata, all types of fibroblasts rapidly begin to migrate down into the three-dimensional collagen matrix. We have previously demonstrated that normal (adult and foreskin), foetal and transformed fibroblasts may be distinguished from each other by virtue of their differential migratory response to changes in cell density. The effects of cell density on fibroblast migration into the gel may be expressed by a single numerical value, the ‘cell density migration index’ (CDMI). We now present evidence that ostensibly normal skin fibroblasts obtained from the majority of patients we examined with carcinoma of the breast, malignant melanoma, familial polyposis coli, retinoblastoma and Wilms’ tumours display aberrant CDMI values falling within the foetal range. Skin fibroblasts obtained from the majority of patients examined with genetic or chronic diseases (e.g. rheumatoid arthritis, Duchenne muscular dystrophy) displayed CDMI values falling within the normal range.
Isolation and characterization of macronuclei of Paramecium caudatum infected with the macronucleus-specific bacterum Holospora obtusa
Authors: Freiburg Manfred 
Published: April 2021

ABSTRACT
Macronuclei from Paramecium caudatum infected with Holospora obtusa may be isolated on sucrose step gradients. Macronuclei containing primarily infectious forms can be separated from those bearing predominantly reproductive forms. RNA polymerase activity in infected macronuclei is greater by a factor of 5 than that in uninfected macronuclei. Proteinase activity is also significantly higher.
Sperm-oocyte interaction in the sea-urchin
Authors: Dale Brian , Santella Luigia 
Published: April 2021

ABSTRACT
A study was made of the electrical and morphological changes in the sea-urchin oocyte during interaction with spermatozoa. The first event, a small step depolarization accompanied by a 20—40% decay in input resistance occurs within seconds of attachment. The evidence suggests that this electrical event is the result of sperm—oocyte fusion, and that the ion channels that lower the resistance across the oocyte-sperm complex are located in the sperm plasma membrane. This primary electrical event does not necessarily lead to sperm incorporation. A second, determinative, event occurs at 50 s, which leads to sperm entry and the formation of a cytoplasmic protrusion at the site of sperm entry. This second event probably results from the transfer of a soluble component from the spermatozoon into the oocyte cytoplasm, which leads to sperm incorporation and formation of the protrusion. The changes in the oocyte following insemination are compared with the events of egg activation.
Apoptosis as the mode of cell death in antibody-dependent lymphocytotoxicity
Authors: Stacey N. H. , Bishop C. J. , Halliday J. W. , Halliday W. J. , Cooksley W. G. E. , Powell L. W. , Kerr J. F. R. 
Published: April 2021

ABSTRACT
A light and electron microscopic study of antibody-dependent lymphocytotoxicity was carried out with the object of elucidating the mechanisms responsible for the cell killing, the basis for the research being the relationship that has recently been shown to exist between the morphology of cell death and its pathogenesis. Chang liver cells coated with a rabbit anti-human antibody were used as targets and normal human peripheral-blood lymphocytes as effector cells.
Cytotoxicity assays using release of 51Cr demonstrated extensive K-cell killing, thus validating the suitability of the model for morphological studies. Cell death displaying the features of apoptosis correlated with K-cell activity. A small amount of cell death by classical necrosis was observed, but its extent appeared to be unrelated to the presence of lymphocytes, to pre-treatment of the target cells with antibody, or to the magnitude of 51Cr release.
The results support evidence indicating that lymphocytotoxicity depends on activation of a selfdestruct program within the target cell. They do not favour a mechanism involving the production of plasma membrane lesions analogous to those responsible for complement-mediated immune cytolysis.
Production and functional properties of eosinophils from bone marrow cultures
Authors: Strath Malcolm , Sanderson Colin J. 
Published: April 2021

ABSTRACT
Bone marrow cultures have been established from mice infected with Mesocestoides corti and undergoing parasitic eosinophilia. In the absence of added conditioned medium, eosinophil differentiation ceases, and eosinophils are undetectable by 7 days, whereas neutrophil production continues over several weeks as with normal bone marrow. Eosinophil production can be induced by adding pokeweed mitogen-stimulated spleen supernatants (MSSS) or specific antigen-stimulated spleen supernatants (ASSS) produced from spleen cells of M. corti-infected mice. In contrast to the continuous production of neutrophils, eosinophil production is transient, suggesting that there is no continued production of eosinophil progenitor cells in these cultures. More eosinophils are produced when MSSS is added at the initiation of cultures, compared to after a delay of 2 weeks, and establishing the cultures at 33 °C does not appear to enhance eosinophil production.
The eosinophils produced are shown to express the eosinophil differentiation antigen defined by monoclonal antibody NIMP-R13, they produce eosinophil peroxidase in similar amounts to eosinophils taken from mice. They show normal phagocytic activity of antibody-coated erythrocytes and lyse red cells coated with antibodies of IgGl, IgG2a, IgG2b, but not IgM isotypes.
Correlations between characteristics of some free-living Chlorella sp. and their ability to form stable symbioses with Hydra viridis
Authors: Rahat M. , Reich V. 
Published: April 2021

ABSTRACT
Aposymbiotic polyps of Hydra viridis were infected with 17 strains of in vitro cultured Chlorella sp. Larvae of Artemia fed with the chlorellae were used as an infecting vector.
Of the 17 strains, seven formed stable symbioses and one formed a transient infection that disappeared within several weeks. Chlorellae of the nine other strains were cleared out of the infected hydra within 2–3 days.
There was a distinct correlation between the ability of the chlorellae to form stable symbioses and their ability to adapt and grow in media enriched with 0·5% proteose peptone. Only strains that grew in the latter medium formed symbioses with the hydra.
The symbioses formed with the different strains of chlorellae differed from one another. Hydra infected with some strains greened completely while those infected with other strains greened only partially. The degree of infection varied also within each population, and there were differences in the distribution of the various chlorellae along the stalk and inside the digestive cells of the hydra. Growth rates of the infected hydra were all less that those of aposymbiotic hydra or of hydra hosting native zoochlorellae.
We conclude that adaptability to a nutrient-rich environment inside the perialgal vacuole of the digestive cell and a sufficient growth rate therein are crucial to the ability of chlorellae to form stable symbioses with H. viridis. In time, co-adaptation of hydra and chlorellae would restore the normal growth rate of the former and bring about regularity to the form and extent of infection by the latter.
Morphological changes in rat tracheal cells during the adaptive and early growth phase in primary cell culture
Authors: Chang Ling-Yi , Wu Reen , Nettesheim Paul 
Published: April 2021

ABSTRACT
The purpose of our studies was to determine the fate of different cell types present in early primary cultures of tracheal epithelial cells and, if possible, to elucidate the role they play in the establishment of the cultures. Epithelial cells were isolated from rat trecheas with 0’5% Pronase and were cultured on collagen-coated dishes as described previously. Light and transmission electron microscopic studies showed that the cell population harvested from rat trachea was composed of approximately 30% ciliated cells, 50% granule-containing cells and 20% undifferentiated cells (presumably basal cells). Upon seeding the tracheal cell suspensions into culture, ∼ 40% of the cells attached. Cell attachment was virtually complete after 16 h. Roughly 60% of the cells attaching during the first 12 h were neither ciliated nor granulated, suggesting that undifferentiated cells played a major role in establishment of the early cultures. Between 20 and 35% of the cells attaching during this time were identified as granulated cells (mucous cells). Ciliated cells did not start to attach in significant numbers until 8 h after seeding. They never amounted to more than 8–12% of the attached cell population.
After 12 h of culture, the cell population underwent a progressive loss of differentiation. The number of poorly differentiated cells (i.e. those showing neither cilia nor mucous granules) increased correspondingly. This loss of differentiation preceded the onset of DNA synthesis and cell growth which began at about 24 and 40 h, respectively. Continuous [3H]thymidine-labelling studies showed that at 48 h after the start of culture about 90% of all attached cells had entered DNA synthesis at least once. This finding is consistent with the interpretation that the ciliated cells are terminally differentiated cells and are probably the only part of the tracheal cell inoculum not participating in the growth of the cultures.
At 72 h, the cultures (now in mid-log growth phase) were composed of uniformly undifferentiated cells lacking cilia and mucous granules. The cells nevertheless showed unequivocal epithelial characteristics such as tight junctions and desmosomes.
The studies suggest that both basal and mucous cells are responsible for the establishment and growth of the rat tracheal epithelial cell cultures.
Ultrastructural changes in gap junctions associated with co2 uncoupling in frog atrial fibres
Authors: Mazet F. , Dunia I. , Vassort G. , Mazet J. L. 
Published: April 2021

ABSTRACT
The correlation between gap junction morphology and the state of electrical coupling was investigated in the frog auricle, which presents an atypical gap-junction organization. Electrical uncoupling of the tissue was achieved by perfusion with CO2 -saturated Ringer medium. The tissue was fixed with glutaraldehyde and freeze-fractured before and during the application of CO2 -saturated Ringer medium and after returning to the initial medium. The electrical tissue coupling was assayed by microelectrode recording just before fixation. At least 97% uncoupling was induced by CO2 -saturated Ringer medium, as estimated from double sucrose gap experiments on several single atrial trabeculae.
Several modifications were induced by CO2 -saturated Ringer medium. A decrease in the number of particles per junctional assembly and dispersion of these assemblies in the plane of the membrane, indicate a decrease in the organization of the gap junctions. In parallel, loose clusters of particles became evident on the P-fracture face of the membrane. The size of the particles in these clusters was larger than the size of the background particles, and of the gap junction particles. They never corresponded with complementary pits on the E-fracture face. On return to the initial Ringer perfusion medium the cell coupling was reversed and the gap junction dispersion was also reversed. However, the gap junctions remained small. The relationship between these morphological modifications and the conducting state of the tissue is discussed.
A subclass of luminal epithelial cells in the human mammary gland, defined by antibodies to cytokeratins
Authors: Bartek J. , Durban E. M. , Hallowes R. C. , Taylor-Papadimitriou J. 
Published: April 2021

ABSTRACT
Two monoclonal antibodies, BA16 and BA17, have been developed using a detergent-insoluble extract of human mammary epithelial organoids as immunogen. Indirect immunofluorescent staining of cultured cells showed that the component reacting with the antibodies was filamentous and the intensity of staining was stronger in mitotic cells. Immunoblotting of cell extracts showed that both antibodies react with only one band of 40× 103 molecular weight, which was present in keratin-enriched extracts of cells or organoids. Furthermore, the tissue distribution of the component reacting with the antibodies was that predicted for human keratin 19. The antibodies showed differences in the intensity of staining of cells or tissue sections fixed and prepared in different ways indicating that they reacted with different epitopes. The pattern of expression of the 40×103Mr keratin by normal mammary epithelial cells was investigated by immunoperoxidase staining of tissue sections, cultured milk cells, and organoids of different sizes cultured in collagen gels. It was found that basal or myoepithelial cells did not express this keratin. Some heterogeneity of expression of this component was seen in luminal epithelial cells, found almost exclusively in the smaller structures. These cells did, however, express other keratins characteristic of luminal cells. The distribution in the mammary tree of the luminal cells that did not express the 40 × 103Mτ keratin appears to be similar to that expected for cells with the proliferative potential to produce new terminal ductal lobular units or an increase in branching of existing terminal ductal lobular units. It is shown that these cells have considerable proliferative potential by the fact that they form large colonies in milk cell cultures.
Capsella embryogenesis: The chalazal proliferating tissue
Authors: Schulz Patricia , Jensen W.A. 
Published: April 2021

ABSTRACT
Electron-microscope and histochemical procedures were used to study the development and breakdown of the chalazal proliferating tissue in Capsella. This tissue is formed by the enlargement of several layers of nucellar cells at the chalazal end of the embryo sac. When the embryo reaches the early globular stage these enlarged cells start to disintegrate, beginning with those immediately bordering the embryo sac and continuing until all have broken down. Characteristic ultrastructural changes accompany the development and breakdown of the chalazal proliferating cells. The mature cells form increased numbers of dictyosomes and large amounts of endoplasmic reticulum (ER). This is accompanied by a thickening of the cell wall. As the cells begin to break down, electron density increases, plastids become polarized in the cells, dictyosomes disappear and the ER is dispersed and fragmented. Plastids, some mitochondria, and pieces of ER appear to be digested in autophagic vacuoles. Cell disorganization is accompanied by an increased number of microbodies and multivesicular bodies per cell. Finally, the nucleus breaks down and the plasmalemma disappears. The end wall ruptures and releases intact mitochondria, ribosomes, and portions of degenerated cytoplasm into the endosperm. Histochemical changes accompany these events. Also discussed are the antipodals and the destruction of the proximal part of the chalazal nucellus by the expanding megagametophyte prior to the development of the chalazal proliferating tissue.
The analysis of malignancy by cell fusion: I. hybrids between tumour cells and l cell derivatives
Authors: Klein G. , Bregula U. , Wiener F. , Harris H. 
Published: April 2021

ABSTRACT
A wide range of different kinds of malignant cell were fused with certain derivatives of the L cell line and the ability of the resulting hybrid cells to grow progressively in vivo was examined. In all cases the highly malignant character of the tumour cells was suppressed by fusion with the L cell derivatives, whether or not these had metabolic defects that facilitated selection of the hybrid cells. So long as the hybrid cells retained the complete chromosome complements of the two parent cells, their ability to grow progressively in vivo was very limited, for tumours composed of such unreduced hybrids were not found. However, when they lost certain specific, but as yet unidentified, chromosomes, the hybrid cells regained the ability to grow progressively in vivo and gave rise to a tumour. These findings thus indicated that the L cell derivatives contributed something to the hybrid that suppressed the malignancy of the tumour cell, and that this contribution was lost when certain specific chromosomes were eliminated.
The quantitative glucose and mineral nutrient requirements of mouse LS (suspension) cells in chemically defined medium
Authors: Birch J. R. , Pirt S. J. 
Published: April 2021

ABSTRACT
The influences of glucose, phosphate, magnesium and potassium concentration on growth rate and maximum population density were studied. From the data obtained the growth yields for glucose and phosphorus were found to be 2·4× 106 cells (i.e. 0·76 mg dry weight)/mg glucose and 2·2 × 106 (i.e. 69 μg dry weight) μg P. The growth response to magnesium and potassium was complex since there were threshold concentrations of these metals below which no growth occurred. The growth yield for potassium (2·4 × 105 cells (i.e. 75μg dry weight) μg K) was obtained by measuring potassium uptake during growth. Omission of calcium ions from the medium resulted in poor reproducibility of growth.