bluuebunny/crossref_metadata_2025_split huggingface dataset:
Monoclonal antibody to a 43 000 M
r surface protein of a human leukaemia cell line (thp-1) crossreacts with the fibroblast intermediate filament protein vimentin
Authors: Herrmann Harald , Aberer Werner , Majdic Otto , Schuler Gerold , Wiche Gerhard 
Published: April 2021

ABSTRACT
Monoclonal antibodies were produced against surface antigens of live cells from a human acute monocytic leukaemia cell line (THP-1). One clone, VIC-C2, when assayed by immunofluor-sscence microscopy, brightly stained the surface of THP-1 cells and the cytoplasm of Langerhans cells, fibroblasts and melanocytes in sections of human skin. The immunoreactive cytoplasmic structures were filamentous and resembled intermediate filaments. By double immunofluorescence microscopy using VIC-C2 and polyclonal antibodies to vimentin, the VIC-C2 antigen was shown to be located on intermediate filaments of cultured fibroblasts and to follow these filaments during various drug-induced rearrangements. As demonstrated by immunoprecipitation, antibody gel overlay and immunoblotting of two-dimensional polyacrylamide gels, VIC-C2 recognized two different antigens in extracts of THP-1 cells: one of Mr = 43000 and pl = 7, the other of Mr = 57000. In extracts from various cultured fibroblast cells only the 57 000Mr antigen was detected. This 57000AL protein was identified as vimentin by immunoblotting of rat glioma C6 cytoskeletons on two-dimensional gels. When vimentin was digested with chymotrypsin, only fragments containing parts of both helical rod pieces and the connecting non-helical spacer-region were strongly antigenic, whereas the helical rods alone were only weakly crossreactive. Moreover, immunoprecipitation revealed that VIC-C2 preferentially reacted with native compared to denatured vimentin.
Electron probe x-ray microanalysis of the effects of Bacillus thuringiensis var Kurstaki crystal protein insecticide on ions in an electrogenic k+-Transporting epithelium of the larval midgut in the lepidopteran, Manduca sexta, in vitro
Authors: Gupta Brij L. , Dow Julian A. T. , Hall Theodore A. , Harvey William R. 
Published: April 2021

ABSTRACT
An alkaline hydrolysate of Bacillus thuringiensis var kurstaki HD 1 (Btk) parasporal crystals was administered at 25 μgml-1 (f.c.) to isolated, short-circuited, midguts of tobacco homworm (Manduca sexta) larvae. The short-circuit current (s.c.c.), a precise measure of K+ active transport, was inhibited by 78% in 10 min in Btft-treated midguts as compared to controls. The elemental concentrations of K, together with Na, Mg, P, S, Cl and Ca, as well as the water content, were determined by electron probe X-ray microanalysis (EPXMA) in the muscle cells, columnar cells and goblet cells, as well as in the extracellular goblet cavity and the bathing media. The average K concentration in the goblet cell cavity was 129mmol/kg wet wt in control midguts but only 37 mmol/kg wet wt in fitA-treated midguts. The elemental concentrations, including that of K, in other cell compartments were much less affected by Btk, but a rise in total cell calcium is suggested. It has been previously suggested that in vivo Btk acts specifically on limited regions of the apical membrane of the midgut epithelial cells. The simplest interpretation of the EPXMA results would be that initially Btk interacts specifically with the goblet cell apical membrane, which bounds the goblet cavity and contains the K+ pump responsible for the s.c.c. and high transepithelial potential difference (p.d.). Such interaction results in a rapid disruption of K+ transport across the goblet cell apical membrane, leading to dissipation of the K+ gradient and loss of p.d. The histopathological changes previously reported by other workers would then be a consequence of K+ pump inhibition causing changes in the intracellular pH, Ca2+ etc. Some possible molecular bases for these specific interactions between Btk and cell membrane are discussed.
Isolation and partial characterization of Urechis caupo egg envelopes
Authors: Cross Nicholas L. , Slezynger T. C. , Holland Linda Z. 
Published: April 2021

ABSTRACT
Eggs of Urechis caupo are surrounded by a≃0·9 μm thick egg envelope and, attached to that, a peripheral jelly layer about 3 μm thick. Before fertilization, the sperm undergoes the acrosome reaction and binds to the egg envelope. As part of a study of the induction of the acrosome reaction and sperm binding in Urechis, we have developed a method to prepare an egg envelope fraction by differential centrifugation. The isolation procedure removes much of the jelly layer, but does not alter the fine structure of the envelope. When a sperm contacts an isolated envelope, it undergoes a normal acrosome reaction and binds to the envelope’s outer face. Electrophoresis of the envelope fraction on sodium dodecyl sulphate (SDS)/polyacrylamide gels revealed six major components stained by Coomassie Blue, of which four are stained by the periodic acid-Schiff reagents (PAS). To measure the degree of enrichment of the envelope fraction, envelopes were isolated from eggs that had been externally radio-iodinated; the specific activity of the envelope fraction was 17 ± 3 times greater than that of intact eggs. The amino acid composition of the envelope fraction is dominated by Gly (19 mole%), Asx (11%), Thr (11%), Ser (8%), Ala (8%) and Glx (8%). The sugars fucose, xylose, mannose, galactose, glucose, jV-acetylglucosamine and N-acetylgalactosamine were detected by gas-liquid chromatography. We also investigated whether the egg envelope changes at fertilization. No change was detected in the electrophoretic 125I pattern of externally radio-iodinated eggs, and the envelope fractions prepared from unfertilized and fertilized eggs produced the same Coomassie Blue pattern on SDS/polyacrylamide. gels.
Inhibition of cell spreading on the band of extracellular fibres in early chick and quail embryos
Authors: Andries L. , Vanroelen Ch. , Hoof J. Van , Vakaet L. 
Published: April 2021

ABSTRACT
The ventral surface of the upper layer shows a band of extracellular fibrils around the anterior and lateral border of tfieareapellucida during gastrulation of the chick embryo. Using scanning electron microscopy, we found that this disposition is correlated with the motility of the middle-layer cells of gastrulating chick and quail embryos. Outside the fibrous band, single middle-layer cells and a sheet of mesoblast cells were spread out and possessed lamellae. Single cells on the fibrous band did not form lamellae. The same cell behaviour was obtained with the expiants of deep layer on the fibrous band. The fibrous band is assumed to operate as a barrier that inhibits cell motility during gastrulation.
Extraction model of the longitudinal flagellum of Ceratium tripos (dinoflagellida): Reactivation of flagellar retraction
Authors: Maruyama Tadashi 
Published: April 2021

ABSTRACT
The mechanism of retraction of the longitudinal flagellum of Ceratium tripos was studied by making extracted models of the flagellum. Non-detergent models extracted in low ionic strength medium containing 1 M-glucose, 10mM-EDTA and 50mM-Tris. HCl buffer (pH8·0), retracted when Ca2+, Mg2+, Ba, Sr2+, Mn2+ or Cd2+ was applied locally with a glass capillary. A demembranated model of the flagellum was made with an extraction medium containing 0·8-TO M-glucoβe, 20mM-Tris-acetate (pH7·8), 2mM-EGTA, 5–7mM-MgS04, 0·l M-potassium glutamate and 0·l% Triton X-100. The model required a concentration of Mg2+ of a few mmol/1 for successful reactivation of both retraction and undulation, and about 0·l M-potassium glutamate (or sodium glutamate) for reactivation of undulation. Neither type of motion of the models could be reactivated above 35 °C. Ca2+ induced the retraction at pCa 5·5 or less. In addition to Ca2+, Mn2+, Ba2+, Sr2+ and Cd2+ also induced retraction but Mg2+, La3+ or Tb3+ did not. Although ATP was required for undulation, it was not required for retraction. Co-incubation with hexokinase to remove contaminating ATP did not suppress the retraction. The potent ATPase inhibitor, orthovanadate, inhibited undulation at 10μM but did not inhibit retraction even at 2mM. SH blockers, N- ethylmaleimide and dithio-bis-nitrobenzoic acid strongly suppressed undulation but had no effect on retraction. Calmodulin inhibitors, trifluoperazine and chlorpromazine, also had no effect on retraction. These data indicate that undulation is generated by a 9+2 microtubular axoneme using energy released by hydrolysis of ATP and that retraction can be induced by Ca2+ without a requirement for ATP.
Architecture of the microtubule component of mitotic spindles from Dictyostelium discoideum
Authors: Mcintosh J. R. , Roos U.-P. , Neighbors B. , McDonald K. L. 
Published: April 2021

ABSTRACT
Ten mitotic spindles from Dictyostelium discoideum have been studied by electron microscopy of serial sections. We have used computer graphics to track individual microtubules (MTs) in three dimensions and to compare seven spindles at different stages of anaphase and telophase. The central spindle of early anaphase is formed by the interdigitation of two sets of pole-associated MTs. The distribution of MT lengths at this stage is hetero-disperse. During anaphase total MT length decreases by a factor of about 2 as a result of two opposing changes in MT length: the longer MTs that interdigitate become even longer, while the short MTs, including those attached to kineto-chores, become shorter still and decrease in number. The extent of MT interdigitation is less in longer spindles than in short ones. In metaphase and early anaphase, the MTs are not in an ordered arrangement as seen in spindle cross-sections, but as anaphase proceeds the MTs cluster into a square-packed, paracrystalline bundle in which most of the nearest neighbours come from opposite poles. This arrangement and the condensation-like increase in order suggest the existence of specific interactions between antiparallel MTs. A quantitative analysis of MT positions supports this interpretation, but direct evidence for convincing bridges between MTs is lacking. The pole-distal ends of the MTs that interdigitate show an irregular termination (C-shaped ends in transverse view), as is characteristic of MTs that are either adding or losing subunits. Since it is these interdigitating MTs that elongate, and since the shortening MTs show the customary blunt endings, we conclude that subunits add to the interdigitating MTs at their pole-distal ends. This inference, combined with other structural data, suggests that the interdigitating MTs of Dictyostelium are sliding over one another as they polymerize in anaphase. It also suggests a simple model for why the spindle becomes thinner as it elongates. We propose that MT interdigitation defines a region where MTs bind a factor that will associate only with antiparallel MTs. This factor biases the MT assembly equilibrium toward polymer. As the shorter MTs slide out of this region, they lose their polymerization advantage and depolymerize, releasing subunits to contribute to the further elongation of the already longer MTs. The properties of the Dictyostelium spindle are compared with those of both higher and lower eukaryotes.
Ultrastructural features of transneuronal cell degeneration in the olfactory system
Authors: Pinching A. J. , Powell T. P. S. 
Published: April 2021

ABSTRACT
The electron microscope has been used to study transneuronal degenerative changes in the cells of the olfactory bulb of the rabbit and rat following removal of the olfactory mucosa. The principal features of this type of change are cell shrinkage, a concentration of cytoplasmic and nuclear constituents, an alteration in the organization of nucleic acid material, and a swelling of membrane-bound systems; some elements of cellular organization appear unchanged, including synaptic specializations. The changes are described for each part of theneuron.—soma, dendrite, axon and terminal—as well as the variants found in different cells. The degree of morphological alteration appears to be related to the extent of denervation for any individual cell and does not seem to be sequential. These changes are related to findings on altered impregnation properties of the same cells with the Golgi technique and are discussed in the context of the functional alteration produced by deafferentation. A new interpretation of some ‘dark neurons’ is also suggested on the basis of these findings.
Protein composition of nuclear matrix preparations from hela cells: An immunochemical approach
Authors: Verheijen Ron , Kuijpers Helma , Vooijs Peter , Van Venrooij Walther , Ramaekers Frans 
Published: April 2021

ABSTRACT
Procedures for the isolation of HeLa S3 nuclear matrices were re-examined with special emphasis on the use of various nucleases and detergents as well as on the ionic strength of the final salt extraction.
The protein composition of the resulting nuclear matrix preparations was analysed by one- and two-dimensional gel electrophoresis and found to be extremely reproducible. By means of co-electrophoresis several typical cytoskeletal proteins (actin, vimentin and cytokeratins) and heterogeneous nuclear RNA (hnRNA)-associated core proteins (hnRNP) were shown to be present in such nuclear matrix preparations. The nature of some other protein components was elucidated using two-dimensional immunoblotting and immunofluorescence. For this purpose mouse monoclonal antibodies to cytokeletal components (vimentin, cytokeratins), small nuclear RNP (70× 103Mr protein of U1-RNP), hnRNP (C1/C2) and the pore-complex lamina (lamins A, B and C) were used next to human autoimmune sera obtained from patients with connective tissue diseases and directed against the residual nucleoli and the internal fibrillar mass. These antibodies enabled us to identify a number of proteins present specifically in the nuclear matrix and to show that part of the cytoβkeletal proteinβ are still present in the isolated structures.
Distribution of chromomeres as a basis of chromosomal coiling
Authors: Sorsa Veikko 
Published: April 2021

ABSTRACT
Periodicity in the distribution of prominent bands was analysed from the light and electron microscopic maps of salivary gland chromosomes of Drosophila melanogaster. The data obtained indicate that a similar distribution of prominent chromomeres in an individual interphase chromatid results in a unilateral accumulation of chromatin at the chromonema stage, if the helical axis of chromonema consists of ∼5-9 interchromomere + chromomere units per turn. Orientation of the largest chromomeres mainly on one lateral half and the smallest chromomeres mainly on the opposite lateral half of the chromonema apparently bends it to form the chromosomal ‘macro’ coil. Thus the increase in DNA content in the chromomeric loops located at specific intervals along the chromatids may have an important role in the evolution of coiling hierarchy in the eukaryotic chromosomes.
Immunocytochemical differentiation of microtubules in the cytoskeleton of Giardia lamblia using monoclonal antibodies to α-tubulin and polyclonal antibodies to associated low molecular weight proteins
Authors: Crossley Richard , Marshall Jonathan , Clark John T. , Holberton David V. 
Published: April 2021

ABSTRACT
In interphase trophozoites of Giardia lamblia, separate populations of microtubules constitute the four parts of the mastigont apparatus: flagella, ventral disc, funis and median body.
Antigenic differences between the tubules have been investigated by light and electron immunocytochemistry after labelling with two monoclonal antibodies to α-tubulin (YL 1/2 and YOL 1/34 clones), and with polyclonal antibodies to Giardia tubule-associated proteins. Both anti-tubulins stained all tubules after isolated structures were fixed in formaldehyde, but different patterns of reactivity were shown by unfixed tubules. YL 1/2 antibodies labelled flagellar axonemes and basal bodies, funis and median body tubules. Disc microtubules were mostly unlabelled, but the antibody bound strongly to the outer edge of the disc where the ends of tubules are embedded. YOL l/34 antibodies stained disc tubules uniformly, and cross-reacted with the median body but not with tubules of axonemes, basal bodies or funis.
Antibodies to giardins 14A and 14B (∼30000 Mr filament-forming proteins) localized these proteins in the microribbons attached to disc microtubules. The median body was also labelled by anti-giardins, indicating an ontogenetic relationship between this organelle and the ventral disc.
A second set of ∼30000 Mr proteins with no immunoreactivity to anti-giardin was found in flagella purified without removing flagellar membranes. These polypeptides were Triton-soluble and therefore probably originated from an extra-axonemal site. A rabbit antiserum to the labile flagellar proteins specifically stained the two ventral flagella, but not the other six flagella on this cell.
Surface glycoproteins of human spermatozoa
Authors: Kallajoki M. , Virtanen I. , Suominen J. 
Published: April 2021

ABSTRACT
The surface membrane glycoprotein composition of human spermatozoa has been studied by introducing radioactive label into galactosyl (Gal) and N-acetylgalactosaminyl (GalNAc) residues by using the galactose oxidase/NaB3H4 method. Triton X-100 extracts and Triton X-100-resistant cytoskeletal residues were subjected to analysis by polyacrylamide gel electrophoresis.
The distribution of the radiolabel in sperm cells was studied by light-microscopic autoradiography. The grains were evenly distributed on the cells by the labelling methods used. The Triton X-100 treatment did not affect sperm morphology at the light-microscopic level, but in transmission electron microscopy the plasma membrane covering the acrosome was removed totally, together with most of the acrosomal membranes and acrosomal contents. Plasma membrane residues were, however, always found in the postacrosomal region.
Borohydride alone without oxidative pretreatment labelled two polypeptides of molecular weights (Mr) 48000 and 43 000 in the Triton X-100-soluble fraction. When the Gal/GalNAc residues were labelled by galactose oxidase pretreatment 120000, 105 000, 78000 and 68 000Afr glycoproteins were revealed. When additional neuraminidase treatment was used to remove terminal sialic acid residues, the total labelling intensity was increased two-to fivefold and additional 36000 and 20000Mr glycoproteins were revealed. The Triton X-100-resistant cytoskeletal residue contained 53–75% of the total radioactivity bound in sperm cells. When these components were analysed by polyacrylamide gel electrophoresis, all the major bands found in the Triton X-100-soluble fraction were detected and also some radioactivity was incorporated into the major bands visualized by protein staining. In the present study we describe several human sperm glycoproteins, which seem to be distributed evenly on the sperm cells. Detergent extraction, producing cytoskeletal models, appeared to leave most of the glycoproteins detectable in the extraction residues also with the apparent enrichment of a single 68 000Mr glycoprotein.
Nuclear antigens follow different pathways into daughter nuclei during mitosis in early Drosophila embryos
Authors: Frasch Manfred , Glover David M. , Saumweber Harald 
Published: April 2021

ABSTRACT
In the early embryonic development of Drosophila melanogaster, there is a series of 13 rapid and highly synchronous nuclear divisions. We have used a collection of monoclonal antibodies to follow the re-distribution of nuclear antigens into daughter nuclei at this developmental stage by indirect immunofluorescence microscopy. The antigens fall into several categories in terms of the pathways that are followed at mitosis. At one extreme is a group of antigens that remains continuously associated with the DNA throughout all the mitotic phases. At the other extreme, another group of antigens is excluded from the nucleus at prophase, and does not associate with the nucleus again until late telophase. One antigen, which becomes incorporated into the nucleolus at cellularization after the thirteenth division, becomes associated with the chromosomes during mitosis, but not until anaphase. Several different antibodies stain a diamond-shaped compartment that develops over the spindle at anaphase. The distribution of antigens within this spindle compartment shows some variation: one antigen appears to be present at higher concentrations in the central region of the spindle; others appear in three quite distinct areas corresponding to the positions of the new daughter nuclei and the old parental nucleus. Yet another antibody gives uniform staining of the spindle compartment. This antibody also recognizes a protein present in centrosomes.
Signal transduction in human neutrophil leucocytes: Effects of external Na+ and Ca2+ on cell polarity
Authors: Haston Wendy S. , Shields James M. 
Published: April 2021

ABSTRACT
Stimulation of neutrophil leucocytes with chemotactic factors is known to result in membrane permeability changes, as evidenced by fluxes of Na+ and K+ across the cell membrane together with an increased uptake of Ca2+ from the medium. These fluxes have been implicated in the transduction mechanisms of various responses, including locomotion and subsequent chemotaxis. We have previously reported that exposure of unstimulated, round neutrophils held in suspension, to the chemotactic peptide fMet-Leu-Phe confers morphological polarity on the neutrophils by stimulating waves of contraction, which are also intimately connected with locomotion on an appropriate substratum. As the acquisition of polarity is the important first step in the chemotactic response we have investigated the effects of modifying the external ionic environment and of various ion channel blockers on the polarizing response of neutrophils held in suspension.
Removal and chelation of both Ca2+ and Mg2+ from the external medium did not inhibit the acquisition of polarity and a variety of inorganic Ca2+ channèl blockers together with the organic Ca2+ antagonists, verapamil and D600, were ineffective in inhibiting the response. Replacement of Na+ in the external medium with choline inhibited the polarizing response completely but tetrodotoxin, which blocks fast Na+ channels, and amiloride, which inhibits Na+/K+ exchange, had no effect. Inhibition of the Na+/K+-ATPase with ouabain and also tetraethylammonium ions, which block potassium channels, had no inhibiting effect on polarization. These results indicate that while Ca2+ and Mg2+ are not required in the external medium, Na+ is essential, and therefore Na+/K+ fluxes across the cell membrane play a role in initiating locomotion.
Inositol 1,4,5-trisphosphate and calcium stimulate actin polymerization in Dictyostelium discoideum
Authors: Europe-Finner G. Nicholas , Newell Peter C. 
Published: April 2021

ABSTRACT
The effect of chemoattractants such as cyclic AMP and folate on amoebae of the cellular slime mould Dictyostelium discoideum is to cause a series of rapid intracellular responses. One of the most rapid of these responses is the polymerization of actin associated with the cytoskeleton, an event correlated with pseudopodium formation, which ocurrs within 3—5 s of chemotactic receptor stimulation. We report that this response can be mimicked by addition of 5 μM-inositol 1,4,5-trisphosphate (IP3) or by addition of 100μM-Ca2+ to saponin-permeabilized amoebae.
The data suggest that cytoskeletal actin polymerization occurs in normal cells as a result of IP3 formation in response to cell surface receptor stimulation and the consequent release of Ca2+ from internal stores.