bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cytochalasin-b-binding proteins related to glucose transport across the basolateral membrane of the intestinal epithelial cell
Authors: Uezato Tadayoshi , Fujita Michiya 
Published: April 2021

ABSTRACT
Basolateral membrane vesicles were isolated from mouse enterocytes. The vesicles showed Na+-independent uptake of D-glucose. The uptake was inhibited by cytochalasin B and phloretin with 50% inhibition at 2’0 μM and 25 μM, respectively. 2-Deoxy-D-glucose inhibited D-glucose transport by 50% at 0·5 M. The basolateral membranes bound 13·5 p mol mg protein-1 of 0·1 μM-cytochalasin B. The effects of various monosaccharides on cytochalasin B binding were examined; the strongest inhibitor was 2-deoxy-D-glucose (20-30%). Sodium dodecyl sulphate-polyacryl-amide gel electrophoresis of the basolateral membranes labelled with [3H]cytochalasin B revealed two components with Mr values of 52(±2) and 30×103). Phloretin and 2-deoxy-D-glucose inhibited the photo-incorporation of [3H]cytochalasin B into these components. While phloretin inhibited the photolabelling of the two components to a similar extent, 2-deoxy-D-glucose seemed to inhibit preferentially that into the 52×103Mr component. The similar sensitivity to 2-deoxy-D-glucose of the photolabelling of the 52×103Mr component and of D-glucose transport, together with the fact that dithiothreitol removal increased the incorporation into the 52×103Mr component and decreased that into the 30×103 Mr component, seems to suggest that the 52×103Mr component is the major glucose transporter of the basolateral membrane.
Regulation of intracellular algae by various strains of the symbiotic Hydra viridissima
Authors: Bossert Patricia , Dunn Kenneth W. 
Published: April 2021

ABSTRACT
In observations on three strains of green hydra, the host and the algal mitotic index is closely coordinated only for the smallest. As the hydra strain size increases the coordination of host and algal mitosis progressively breaks down, first in timing for a medium-sized strain and then in rate for a large strain. Despite disparities between host and algal mitotic index, the number of algae per host cell remains constant in all strains during the interval measured. To account for this constancy we suggest that the hydra may either prolong the duration of the algal tetraspore stage or cull excess algae.
Physical association between the peribacteroid membrane and lipopolysaccharide from the bacteroid outer membrane in Rhizobium-infected pea root nodule cells
Authors: Bradley Desmond J. , Butcher Geoffrey W. , Galfref Giovanni , Wood Elizabeth A. , Brewin Nicholas J. 
Published: April 2021

ABSTRACT
Monoclonal antibodies were used as cytochemical markers to study surface interactions between endosymbiotic Rhizobium bacteroids from pea root nodules and the encircling peribacteroid membranes, which are of plant origin. Monoclonal antibodies that react with Rhizobium lipopolysaccharide (LPS) or with a plant membrane glycoprotein were used as markers for material from the bacteroid outer membrane or the peribacteroid membrane, respectively.
Membrane-enclosed bacteroids were isolated from nodule homogenates by sucrose gradient centrifugation, and the encircling peribacteroid membrane was released by mild osmotic shock treatment. Using an immunochemical technique (sandwich ELISA), it was shown that 1–5 % of the LPS antigen released into the peribacteroid fraction by mild osmotic shock treatment was physically associated with peribacteroid membrane through a detergent-sensitive linkage. This association could be visualized when freshly prepared peribacteroid material was immobilized on gold grids and examined by electron microscopy after dual antibody immunogold treatment and subsequent negative staining. The distribution of LPS antigen within infected nodule cells was also investigated by immunogold staining for thin sections of nodule tissue fixed in glutaraldehyde, and a close association between LPS antigen and peribacteroid membrane was often seen.
Nucleoside diphosphokinase, an enzyme with step changes in activity during the cell cycle of the fission yeast Schizosaccharomyces pombe: I persistence of steps after a block to the DNA-division cycle
Authors: Creanor J. , Mitchison J. M. 
Published: April 2021

ABSTRACT
In confirmation of earlier results, nucleoside diphosphokinase is shown to be a ‘step’ enzyme in Schizosaccharomyces pombe with a sharp doubling in activity at the beginning of the cell cycle. These doubling steps occur at the same time in the cycle in the smaller cells of the mutant weel.6. An important result is that the activity steps persist with normal cell cycle timing after a block to the DNA-division cycle imposed by the cell cycle mutants cdc2.33 and cdc2.33 wee 1.6. This is clear proof that oscillatory controls of some cell cycle events can persist after the main periodic events of the DNA-division cycle have been abolished.
Assembly and remodelling of myofibrils and intercalated discs in cultured neonatal rat heart cells
Authors: Atherton B. T. , Meyer D. M. , Simpson D. G. 
Published: April 2021

ABSTRACT
The reorganization of myofibrils and the re-formation of intercalated discs was examined in neonatal rat cardiac muscle cells during the first 72 h of culture. Rhodamine phalloidin was used to monitor the organizational state of the myofibrils and antibodies to desmoplakin and vinculin were used as markers for the presence of desmosomes and fasciae adherentes, respectively. Tiny punctate desmosomes were observed between muscle cells after 24 h and apparently increased in number and/or size between 24 and 48 h in culture. Fasciae adherentes were not detectable with antibodies to vinculin until after 48 h in culture. Well-defined sarcomeres were restored after 48 h in culture. Once formed the sarcomeric organization of the myofibrils was found to be stable provided they were attached to the sarcolemma via intercalated discs. However, if the myofibrils attached to regions of the membrane that lacked intercalated discs the sarcomeres appeared to break down gradually centripetally. When myofibrils attached to the membrane at the free edges of cells that were not in contact with other muscle cells, the striations stopped abruptly at a considerable distance before the myofibril attached to the membrane. These non-striated terminals elongated between 48 and 72 h and were associated with focal contacts that contained vinculin. Overall the results suggest that cell-cell contact may be critical for the stabilization of normal myofibrillar structure in the heart.
Isolation and culture of high endothelial cells from rat lymph nodes*
Authors: Ager Ann 
Published: April 2021

ABSTRACT
The isolation and culture of an enriched population of cells from rat lymph nodes that have several properties of high endothelial cells are described.
High endothelial cells synthesize a unique sulphated glycolipid. This macromolecule in high endothelial cells was labelled with 35SO4 prior to cell isolation and was used to identify high endothelial cells after isolation. Collagenase digestion of pre-labelled lymph nodes yielded primary lymph node cultures in which two different cell types accounted for &gt;90% of non-lymphoid cells isolated. The majority (&gt;70%) were 20–30 μm diameter, round and 35S-labelled and were therefore high endothelial cells. The remaining unlabelled cells were 10–15 μm diameter and were identified as macrophages by phase-contrast microscopy. Isolated cells proliferated after 1–2 days and cultures were enriched for high endothelial cells as macrophages did not persist beyond 7–10 days. Small clumps (2–3 cells) of microvascular endothelial cells and/or adventitial fibroblasts were occasionally seen in primary cultures (⊁1% of isolated cells) but neither cell type proliferated. The identity of high endothelial cells was further substantiated using a polyclonal antiserum raised against lymph node cultures, which stained high endothelium in cryostat sections of lymph nodes. At confluence primary lymph node cultures bound lymphocytes as efficiently as high endothelium in lymphoid tissue and 40-fold more efficiently than rat aortic endothelial cells.
It is concluded that lymph node cultures contain high endothelial cells and that these cells continue to express surface determinants for lymphocytes in vitro.
Different mechanisms mediate structural changes and intracellular enzyme efflux following damage to skeletal muscle
Authors: Duncan C. J. , Jackson M. J. 
Published: April 2021

ABSTRACT
Cellular damage, induced by either A23187 (2×10−5M) or 2,4-dinitrophenol (DNP) (10−3M), has been studied in incubated mouse soleus muscle and has been monitored by electron microscopy and measurement of creatine kinase (CK) efflux. CK efflux induced by DNP was dependent on extracellular Ca, whereas the characteristic myofllament breakdown was not. Chlorpromazine (2 ×10−4M; an inhibitor of phospholipase A (PLA2)) or 5 ×10−6M-nordi-hydroguaiaretic acid (NDGA) (a lipoxygenase inhibitor) almost completely inhibited CK efflux, following treatment with either A23187 or DNP, but did not affect myofilament damage. It is concluded that there are at least two separate pathways in cellular damage: (1) PLA2 activation and lipoxygenase activity culminating in sarco-lemma damage and (2) a system that produces characteristic destruction of the myofilament apparatus.
The ultrastructural localization of luciferase in three bioluminescent dinoflagellates, two species of Pyrocystis, and Noctiluca, using antiluciferase and immunogold labelling
Authors: Nicolas Marie-Thérèse , Sweeney Beatrice M. , Hastings J. Woodland 
Published: April 2021

ABSTRACT
In order to discover the intracellular location of luciferase in dinoflagellates, sections from a number of species were treated with a polyclonal anti-luciferase and the bound antibody was visualized at the electron-microscope level by indirect immunogold labelling.
In two species of Pyrocystis and in Noctiluca, as in Gonyaulax, antibody became bound to dense vesicles, which correspond in size and position to light-emitting bodies detected in previous work. These vesicles resemble microsomes, are bounded by a single membrane and sometimes project into the vacuole.
Unexpectedly, the trichocysts of Gonyaulaxand Noctiluca and the related mucocysts of Pyrocystis also bound the antibody. This cross-reaction seems quite independent of bioluminescence, since the trichocysts of the non-luminous Cachonina also reacted positively. The possibility is discussed that a protein, different from luciferase but having some antigenic similarity, is present in trichocysts and related organelles.
Reactivation of cytoplasmic actomyosin in Physarum plasmodia extracted with glycerol and dimethylsulphoxide
Authors: Bell Renate , Achenbach Friedhelm 
Published: April 2021

ABSTRACT
Thin-spread plasmodia of Physarum were subjected to extraction procedures using 50% glycerol or DMSO (dimethylsulphoxide) followed by labelling of actin with fluorescent phallotoxins.
During the reactivation of the actomyosin system by 2 mM-MgATP fluorescent actin fibres contract isotonically, which results in numerous fluorescent‘contraction beads’.
After short-term extraction 1 mM-Ca2+ has an inhibitory effect on the reactivation. This calcium sensitivity is abolished after long-term extraction with glycerol.
Calcium at 10 mM irreversibly inhibits reactivation, irrespective of the duration of extraction. The inhibitory effect of 10mM-calcium is prevented by phallotoxin labelling prior to incubation in Ca2+.
The DMSO model shows an improvement in structural preservation when compared with the glycerol models. However, reactivation is inhibited by prolonged treatment with DMSO.
Identification of protein antigens associated with the nuclear matrix and with clusters of interchromatin granules in both interphase and mitotic cells
Authors: Turner B. M. , Franchi L. 
Published: April 2021

ABSTRACT
Monoclonal antibody 3C5 recognizes a family of protein antigens present predominantly within the nucleus of interphase cells. We have shown previously that the epitope recognized by 3C5 is phosphorylated and have concluded that the proteins defined by this antibody share a common phosphorylation site. Using a combination of immunofluorescence microscopy and immune-gold labelling in conjunction with electron microscopy, we have studied the distribution of 3C5-reactive material within interphase and mitotic cells. Antibody 3C5 was found to label specific structures within the interphase nucleus that, on the basis of their characteristic granulo-fibrillar morphology and strong staining with bismuth, have been identified as clusters of interchromatin granules (IG clusters). Double-labelling experiments with 3C5 and monoclonal antibodies to DNA have shown that these structures contain no detectable DNA. However, by indirect immunofluorescence, we have shown that 3C5-reactive nuclear structures do label with human autoantibodies to the Sm antigen, a component of small nuclear RNP particles (snRNPs). Granulofibrillar structures that stained strongly with bismuth, and were morphologically identical to nuclear IG clusters, were observed in the cytoplasm of mitotic cells. These structures also labelled with 3C5 but not with anti-Sm anti-bodies. Our results suggest that IG clusters remain essentially intact through mitosis though some snRNP components are apparently lost. In situ extraction of cultured cells with Triton X-100, micrococcal nuclease and 1–2M-NaCl failed to deplete 3C5-reactive material in either interphase or mitotic cells, though some redistribution was evident. In addition, 3C5-reactive proteins were identified in nuclear matrices prepared from rat liver by high-salt extraction procedures. However, the recovery of such proteins was strongly influenced by the preparation technique employed. Our results suggest that 3C5-reactive proteins and IG clusters are anchored to, but not integral components of, salt-resistant structural elements of the interphase nucleus and the mitotic cytoplasm, presumably the nuclear matrix and the cytoskeleton, respectively.
The origin and composition of nucleolus-like inclusions in the cytoplasm of fern egg cells
Authors: Bell P. R. , Pennell R. I. 
Published: April 2021

ABSTRACT
Investigations of oogenesis in a number of lepto-sporangiate ferns have revealed nucleolus-like bodies in the cytoplasm of the maturing egg cells. In Pteridium and Lygodium these bodies appear to be aggregates of material secreted from protrusions of the nucleus. They are acidic in reaction, but autoradiography following feeding with [3H]uridine and the use of an RNase-gold probe, has failed to demonstrate the presence of RNA. Itis concluded that the bodies consist of acidic protein. Since their appearance coincides with an amoeboid condition of the nucleus and extreme dispersal of the chromatin, it is suggested that they represent a temporary storage in the cytoplasm of non-histone structural proteins of nuclear origin.
Conditional absence of mitosis-specific antigens in a temperature-sensitive embryonic-arrest mutant of Caenorhabditis elegans
Authors: Hecht R. M. , Berg-Zabelshansky M. , Rao P. N. , Davis F. M. 
Published: April 2021

ABSTRACT
A monoclonal antibody, specific to phosphor-proteins in mitotic HeLa cells was found to cross-react with a similar set of proteins in embryos of the nematode, Caenorhabditis elegans. In C. elegans, as in mammalian cells, the highly conserved antigenic epitope is associated with a family of high molecular weight polypeptides. The antigenic reactivity of these multiple proteins also depends on their phosphorylation, since antibody binding is reduced after alkaline phosphatase treatment. The antigens are detected at the centrosomes, and in the nuclear region and surrounding cytoplasm of mitotic cells. The significance of these antigens is emphasized by their absence at restrictive temperature in embryos of the temperature-sensitive embryonic-arrest mutant, emb-29V. Furthermore, temperature shift-down experiments suggest that the emb-29 mutation defines a cell division cycle function that affects an essential activity required for progression into M phase.
Regulation of epitectin production in a malignant cell line
Authors: Bader Scott A. , Harris Henry 
Published: April 2021

ABSTRACT
RT112 cells, a line derived from a human bladder carcinoma, produce epitectin at very low levels in standard culture media; but production and secretion of this mucin are greatly increased when the cells are exposed to hyperosmotic conditions. It appears that hyperosmolarity, by inducing an increase in intracellular sodium, entrains an increase in intracellular free calcium. Evidence is presented for the view that it is the increase in intracellular free calcium that provides the more direct stimulus for the enhanced production of epitectin.
Cytoplasmic ph at the onset of development in Dictyostelium
Authors: Aerts Rob J. , Durston Antony J. , Konijn Theo M. 
Published: April 2021

ABSTRACT
Cytoplasmic pH (pH1) was measured by a pH ‘null point’ method in synchronous populations of Dictyostelium discoideum cells. Synchronous populations of vegetative cells with a lower pH1 than asynchronous populations of vegetative cells show a clear preference for the prespore differentiation pathway when they enter development. Treatment of these cells before development with the weak base ammonia results in an increase in pH1 and an abolition of the preference of the cells for the prespore pathway. On the other hand, synchronous populations of vegetative cells with the same pH) as asynchronous populations of vegetative cells resemble these last cells in that they show no preference for a certain differentiation direction when they enter development. However, both these synchronous and asynchronous populations of cells do acquire a preference for the prespore pathway when they are treated before development with the weak acid 5,5-dimethyl-2,4-oxazolidineolione (DMO), which lowers their pH). It is concluded that changes in pH1 at the onset of the developmental program lead to significant changes in the preference of the cells for the prespore differentiation pathway in Dictyostelium discoideum.
Synaptonemal complex spreading in Allium ursinunr. pericentric asynapsis and axial thickenings
Authors: Loidl Josef 
Published: April 2021

ABSTRACT
In Allium ursinum meiotic pairing of homologues is always incomplete; a proximal region on each bivalent remains regularly unsynapsed even in late pachytene. The spatial correlation of the unsynapsed region with the kinetochore suggests that the kinetochore itself exerts an inhibitory effect on synapsis in its vicinity. This can be interpreted as the cytological basis of the ‘centromere effect’ on recombination in this species. Moreover, the high incidence of a pericentric inversion loop in a heterozygous chromosome pair shows that proximal pairing initiation is possible and that its failure cannot be responsible for pericentric asynapsis.
The formation of the inversion loop is complicated by the need for two independent pairing initiation sites because synapsis cannot proceed across the pericentric region. It is proposed that the meiotic bouquet polarization helps in establishing the presynaptic alignment of the homologous sites within the inverted regions and hence to achieve a high rate of inversion loop formation.
Thickenings of the axial/lateral elements are not distributed equally along the synaptonemal complex. They are underrepresented in unpaired axes but strikingly abundant at the borders with synapsed regions, suggesting their origin in the pairing forks during the process of synapsis. They are virtually always present at nucleolusorganizing regions and often they appear at corresponding sites on opposite lateral elements. Besides the thickenings several other kinds of axial deformities are present in unpaired axes.
Reticuloplasmins: a novel group of proteins in the endoplasmic reticulum
Authors: Koch G. L. E. 
Published: April 2021

ABSTRACT
The existence of a special milieu within the endoplasmic reticulum (ER) has been well known to microscopists because of its special osmiphilic properties and the term ‘reticuloplasm’ was coined to describe the contents of the ER (Krstic, 1979). The purpose of this article is to bring together some recent observations showing that reticuloplasm does indeed contain a very special complement of its own resident proteins, referred to as reticuloplasmins, and to consider the possible role of these proteins in ER structure and function.
Enhancement Of Pheomelanogenesis By L-Dopa In The Mouse Melanocyte Cell Line, Tm10, In Vitro
Authors: Sato Chikara , Ito Shousuke , Takeuchi Takuji 
Published: April 2021

ABSTRACT
Cells of TM10, an established cell line, are melanocytes that contain equal amounts of eumelanin (black pigment) and pheomelanin (yellow pigment). The content of pheomelanin drastically increased when the cells were cultured in growth medium containing 0·2mM-L-dopa (L-dihydroxyphenylalanine), which is the common precursor for both eumelanogenesis and pheomelanogenesis.
After this treatment, the amount of pheomelanin was 3·7-fold greater than that of control in TM10, whereas the amount of eumelanin changed very little. In contrast, 5-S-cysteinyl-dopa, which is the specific precursor for pheomelanogenesis downstream of L-dopa, did not cause preferential increase in pheomelanogenesis. Ultrastructural observations also confirmed these results; in 0·2 mM-L-dopa, an increase in the number of pheomelanosomes was observed in the cytoplasm of TM10 cells. Our results also suggest that the L-dopa treatment results in a decrease in tyrosinase activity per melanosome.
Biochemical characterization of isolated CHO cell mitotic spindles: identification of calmodulin-binding proteins
Authors: Brady Richard C. , Schibler Matthew J. , Dedman John R. , Cabral Fernando 
Published: April 2021

ABSTRACTMitotic spindles were isolated from Chinese hamster ovary (CHO) cells and examined morphologically and biochemically. The isolated spindles were observed to be intact structures containing associated chromosomes and were surrounded by a cage of vimentin-containing filaments. Two-dimensional gel electrophoresis of isolated spindles versus whole cell homogenates indicated that isolated spindles were free from significant cytoplasmic contamination and contained tubulin, actin, vimentin and an 80×103Mr quadrapeptide as their major protein constituents. Five calmodulin-binding proteins with molecular weights of 200, 160, 130, 60 and 52(×103) Mr were identified within isolated spindles. These calmodulin-binding proteins may be involved in regulating microtubule organization and depolymerization during karyokinesis.
Clonal analysis in vitro of osteogenic differentiation of marrow CFU-F
Authors: Owen M. E. , Cavé J. , Joyner C. J. 
Published: April 2021

ABSTRACT
Fibroblastic colonies, each of which is derived from a single precursor cell (CFU-F), are formed when suspensions of marrow cells are cultured in vitro. The ability of marrow CFU-F to differentiate in vitro was investigated using the expression of alkaline phosphatase activity as a marker for osteogenic differentiation. In cultures of rabbit marrow cells the colonies formed varied in size, morphology and expression of enzyme activity, indicating that marrow stromal CFU-F are a heterogeneous population. Growth and differentiation of marrow CFU-F can be modified in vitro. Epidermal growth factor increased average colony size and reduced clonal expression of alkaline phosphatase activity to very low levels. Hydrocortisone activated the osteogenic differentiation programme within the cellular progeny of a wide spectrum of CFU-F. The results support the possible development of in vitro clonal methods for the study of differentiation and regulation of the osteogenic and other fibroblastic cell lines of the marrow stromal system.