bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of retinoic acid and dimethylsulfoxide on the morphogenesis of the sea urchin embryo
Authors: Sciarrino Serafina , Matranga Valeria 
Published: September 2002

AbstractSea urchin embryos of the species Paracentrotus lividus were treated continuously with different concentrations of all‐trans retinoic acid (RA) or dimethylsulfoxide (DMSO) at different developmental stages. A delay in embryonic development was observed when embryos were cultured in the presence of 2x10−5 M RA, between 1 and 12 hours of development. Hence, at 48 hours of development, while control embryos had reached the pluteus stage, RA‐treated embryos were at the prism stage. At 72 hours of development RA‐treated embryos recovered and continued normal development reaching the pluteus stage. No effect was observed when treatment was performed before 1 hour or after 12 hours of developmet. DMSO treatment had no effect on normal sea urchin embryo development, although we observed that pigment cells, clearly visible at the pluteus stage, become visible earlier with respect to control embryos. This report confirms the advantages that the sea urchin embryo offers for the study of problems in cellular and developmental biology.
The subcellular localization of newly synthesized cytochrome b5.
Authors: Carlsen Jens , Christiansen Kirsten 
Published: September 2002

AbstractThe fate of newly synthesized cytochrome b5 was studied in rat hepatocytes. Using an antibody specific for microsomal cytochrome b5, we found newly synthesized microsomal cytochrome b5 in both mitochondria and a mitochondria associated membrane fraction as well as in microsomes. Newly synthesized cytochrome b5 was quickly removed from the site of synthesis on free ribosomes and inserted into membranes at random. No migration of newly synthesized cytochrome b5 between cellular compartments was observed and therefore the assembly of the apoprotein with the heme moiety is apparently not taking place in any particular cellular compartment.
Proliferative capacity of embryonic chick notochord: a comparaison between PCNA positivity versus 3H‐thymidine incorporation.
Authors: Ghanem E. , Cornelissen M. , De Ridder L. 
Published: September 2002

AbstractThe proliferation rate of the embryonic chick notochord is measured during its functional period. Chick embryos of 4 different age groups respectively, 3.5, 4.5, 5.5 and 6.5 days of development, are selected. To measure proliferation activity in the notochords, two different methods are used. 1. Notochords are immunostained for proliferating cell nuclear antigen (PCNA). 2. After in vivo incorporation of 3H‐thymidine (3H‐TdR), DNA synthesis is visualized by autoradiography. After embedding in paraffin, 5 μm sections are cut and stained with PC10 monoclonal antibody and avidine biotin peroxidase complex (ABC) technique. Corresponding chick embryos of the same age groups are injected in ovo with 3H‐thymidine. After fixation 2 μm sections are made and exposed for autoradiography. Results obtained by PCNA and autoradiography labelling techniques for the evaluation of the proliferative capacity are different. Both however show a regression of the proliferative activity. The regression of the number of cells that went through S‐phase, as shown by autoradiography, is lower than that of PCNA positive cells. So, a number of notochordal cells stops in G1 phase. Our results moreover, indicate that the proliferating activity of the notochord of chick embryos is higher at young developmental stages than at later stages.
EARLY STEPS OF SPERM—EGG INTERACTIONS DURING MAMMALIAN FERTILIZATION
Authors: BARROS C. , CROSBY J. A. , MORENO R. D. 
Published: September 2002

AbstractMammalian eggs are surrounded by two egg coats: the cumulus oophorus and the zona pellucida, which is an extracellular matrix composed of sulfated glycoproteins. The first association of the spermatozoon with the zona pellucida occurs between the zona glycoprotein, ZP3 and sperm receptors, located at the sperm plasma membrane, such as the 95kDa tyrosine kinase‐protein. This association induces the acrosome reaction and exposes the proacrosin/acrosin system. Proacrosin transforms itself, by autoactivation, into the proteolytical active form: acrosin. This is a serine protease that has been shown to be involved in secondary binding of spermatozoa to the zona pellucida and in the penetration of mammalian spermatozoa through it. The zona pellucida is a specific and natural substrate for acrosin and its hydrolysis and fertilization can be inhibited by antiacrosin monoclonal antibodies. Moreover, inin vitrofertilization experiments, trypsin inhibitors significantly inhibits fertilization. The use of the silver‐enhanced immunogold technique has allowed immunolocalization of the proacrosin/acrosin system in spermatozoa after the occurrence of the acrosome reaction. This system remains associated to the surface of the inner acrosomal membrane for several hours in human, rabbit and guinea‐pig spermatozoa while in the hamster it is rapidly lost. In the hamster, the loss of acrosin parallels the capability of the sperm to cross the zona pellucida. Rabbit perivitelline spermatozoa can fertilize freshly ovulated rabbit eggs and retain acrosin in the equatorial and postacrosomal region. These spermatozoa also show digestion halos on gelatin plates that can be inhibited by trypsin inhibitors. This evidence strongly suggests the involvement of acrosin in sperm penetration through the mammalian zona. Recently it was shown, however, that acrosin would not be essential for fertilization. It is likely, then, that such an important phenomenon in the mammalian reproductive cycle would be ensured though several alternative mechanisms.
EPITHELIAL CELL MIGRATION IN THE INTESTINE
Authors: HEATH JULIAN P. 
Published: September 2002

AbstractDespite significant advances in our understanding of the roles of the cytoskeleton and matrix receptors in cell locomotion, derived largely fromin vitrostudies on the movement of epithelial cell sheets and isolated cells, the mechanism of epithelial cell migration in the adult intestine remains an enigma. The primary function of the epithelial cell cytoskeleton seems to be in the maintenance of the apical region of the epithelium facing the gut lumen. There we find the brush border, with its associated enzymes, and the intercellular adhesion complexes that give the epithelium its cohesiveness and its barrier function. Curiously, there is little in the way of an organized cytoskeleton in the basal region of the epithelium adjacent to the basement membrane on which the epithelium is presumed to migrate. In this short review, I focus on what is known about epithelial migration from our understanding of the structure of the epithelium and from studies on wound healing, and indicate some avenues for future study.
TRANSCELLULAR BIOSYNTHESIS OF CYSTEINYL LEUKOTRIENES BY KUPFFER CELL—HEPATOCYTE COOPERATION IN RAT LIVER
Authors: FUKAI FUMIO , SUZUKI YOSHITAKA , NISHIZAWA YOSHINORI , KATAYAMA TAKASHI 
Published: September 2002

AbstractWe previously proposed that an enzymatic cooperation between Kupffer cells and hepatocytes may play an important role in cysteinyl leukotriene (LT) production in rat liver. Anin vitrotranscellular synthesis cysteinyl LTs by a Kupffer cell—hepatocyte coculture system was characterized here. Kupffer cells alone, with A23187 stimulation, did not generate cysteinyl LTs until supplemented either with isolated hepatocytes or with LTC4synthase and glutathione, indicating that Kupffer cells can synthesize LTA4but not convert it into LTC4. In contrast, hepatocytes converted the LTA4into cysteinyl LTs and further degraded the cysteinyl LTs. Cysteinyl LT production by the Kupffer cell—hapatocyte coculture system was optimized by addition of 1–3% serum albumin to the culture and by bringing the cell—cell distance closer to less than 3μ. Tumour necrosis factor also stimulated cysteinyl LT production by the coculture system. From these results, it is expected that the Kupffer cell—hepatocyte transcellular system for cysteinyl LT production actually functionsin vivo.
INTERCELLULAR COMMUNICATION IN RAPIDLY PROLIFERATING AND DIFFERENTIATED C6 GLIOMA CELLS IN CULTURE
Authors: GHOSH PARAMITA , SINGH UDAI N. 
Published: September 2002

AbstractGlial cells in the brain are known to provide structural and functional supports to neurons. To sustain such a supportive role, they have developed cell‐to‐cell communicating gap junctional channels. The authors studied the effect of dbcAMP on gap junctional channels mediated communication in C6 cells, a rat glioma cell line. Quantitative assessment of coupled cells under microscope after microinjection of a fluorescent dye was taken as a measure of junctional permeability. An enhanced coupling between cells was observed following dbcAMP treatment and this elevated coupling was found to be dependent on the duration of exposure of cells to dbcAMP. The studies have focused on a subtle shift in the spatial organization of the functional channels to the processes of dbcAMP induced differentiated cells from the cell cytoplasms and membranes of dbcAMP untreated cells. Immunofluorescence study with affinity purified antibody against gap junction further confirmed the spatial distribution of gap junctional protein(s) in the processes and also showed an increase in the density of the protein at the intercellular spaces in dbcAMP induced differentiated C6 glioma cells.
MULTINUCLEATION AND PRESERVATION OF NUCLEOLAR INTEGRITY OF MACROPHAGES
Authors: SORIMACHI KENJI , NAORA HONAMI , AKIMOTO KAZUMI , NIWA AKIRA , NAORA HIROTO 
Published: September 2002

AbstractRat bone marrow‐derived macrophages formed multinucleated giant cells spontaneously when cultured in slide glass chambers or when induced with the polyanion acetyl lignin. Nuclei in such cells tended to cluster in distinct rings. DNA fragmentation appeared to occur in multinucleated cells, as detected by 3′ end‐labeling. Southern blot analyses, using probes specific for nucleolar and non‐nucleolar genes, indicated that chromatin DNA was fragmented whereas nucleolar DNA was relatively intact. Autoradiography revealed preservation, in multinucleated cells, of nucleoli into which radiolabeled uridine was incorporated. Multinucleated macrophages appeared to eventually fragment. Preserved integrity of nucleoli seems to be a feature of macrophage multinucleation, a process which apparently culminates in cell death.
CELL‐TO‐CELL COMMUNICATION VIA PLANT ENDOMEMBRANES
Authors: Cantrill L.C , Overall R.L , Goodwin P.B 
Published: September 2002

AbstractCell‐to‐cell communication was investigated in epidermal cells cut from stem internodal tissue of Nicotiana tabacum and Torenia fournieri. Fluorescently labelled peptides and dextrans were microinjected using iontophoresis into the cytoplasm andcortical endomembrane network of these cells. The microinjected endomembrane network was similar in location and structure to the endoplasmic reticulum (ER) as revealed by staining with 3,3′‐dihexyloxacarbocyanine iodide (DiOC6). No cell‐to‐cell movement of dextrans was observed following cytoplasmic injections but injection of dextrans into the endomembrane network resulted in rapid diffusion of the probes to neighbouring cells. It is proposed that the ER acts as a pathway for intercellular communication via the desmotubule through plasmodesmata.
PERMEABILIZATION BY STREPTOLYSIN‐O REVEALS A ROLE FOR CALCIUM‐DEPENDENT PROTEIN KINASE C ISOFORMS ALPHA AND BETA IN THE RESPONSE OF CULTURED CARDIOMYOCYTES TO HYPOSMOTIC CHALLENGE
Authors: Boyle Robert T. , Lieberman Melvyn 
Published: September 2002

AbstractImmunocytochemical techniques indicate that the uninhibited activity of protein kinase C alpha and protein kinase C beta are necessary for a normal regulatory volume decrease (RVD) response of cultured chick embryo cardiomyocytes subjected to a hyposmotic environment. Antibodies against protein kinase C isoforms alpha, beta, gamma and epsilon were introduced into the cultured myocytes using a developed streptolysin‐O (SLO) permeabilization technique that allows the targeted cells to accumulate large biomolecules without perturbing their normal physiological state. The loaded cells were then tested for their ability to RVD when submitted to hyposmotic stimulus. Results show that exposing the cultured cells to SLO in the presence of antibodies against protein kinase C alpha and beta, prior to volume challenge, significantly slows the RVD rate. Additional experiments that combined anti‐alpha and anti‐beta antibodies in the same exposure media did not result in a significantly different rate than the anti‐alpha or anti‐beta rates alone. The evidence gained in this study is in agreement with previous work in the cultured chick embryo cardiomyocyte that report the involvement of a calcium dependent protein kinase C in the signal transduction pathway of the RVD.
CHANGES IN LIVER GANGLIOSIDES IN STREPTOZOTOCIN‐INDUCED DIABETIC RATS
Authors: Sánchez S. S. , Abregú A. V. , Aybar M. J. , Sánchez Riera A. N. 
Published: September 2002

AbstractDiabetes mellitus is associated with various structural and functional liver abnormalities that affect the glycogen and lipid metabolisms. The effects of streptozotocin‐induced diabetes and of insulin supplementation to Sprague—Dawley diabetic rats on ganglioside patterns in liver were determined. Diabetic livers showed a tendency to hepatomegaly 3 weeks after STZ‐induction of diabetes. The concentration of total gangliosides in diabetic and non‐diabetic livers was similar, but the concentration of total gangliosides in the liver of insulin‐stabilized rats was slightly increased. Bidimensional TLC chromatographic analysis of gangliosides isolated from normal diabetic and insulin‐stabilized diabetic livers showed quantitative and qualitative changes. In comparison with normal controls, the densitometric analyses of diabetic liver ganglioside patterns had increased amounts of GM3, GM1, GD1b, and GT1b gangliosides, while GM2 could not be detected. The hepatic ganglioside pattern of insulin‐stabilized diabetic rats was partially restored, resembling the profile of normal rats. The activity of GalNAcT, GalT‐2 and SialT‐4 transferases was measured in liver microsomal fractions of the different groups of animals. Diabetic rats showed an increased activity of GalNAcT and a decrease in the activity of GalT‐2 and SialT‐4 compared with the controls. The enzymatic activities found in insulin‐treated rats showed a tendency to return to the values observed in normal control animals. The results evidenced that streptozotocin‐induced diabetes affects the liver ganglioside pattern and the ganglioside synthesis enzyme activity. The alterations found in ganglioside metabolism could represent one of the earliest changes associated with the diabetic pathology.
ABNORMALITIES OF SPINDLE AND CYTOKINE BEHAVIOR LEADING TO THE FORMATION OF MEIOTIC RESTITUTION NUCLEI IN INTERGENERIC CEREAL HYBRIDS
Authors: Shamina Natalia , Dorogova Natalia , Goncharov Nicolay , Orlova Albina , Trunova Svetlana 
Published: September 2002

AbstractMobile stages of meiosis have been analysed by visualizing the spindle in fertile cereal F1 hybrids. We describe four different mechanisms of the formation of restitution nuclei in meiotic division: (1) centripetal migration of telophase chromosome groups from the poles of a curved spindle at early telophase; (2) centripetal migration of the chromosome groups at late telophase when cell plate formation has failed; (3) preferable migration of univalents to one of the poles although spindle appearance is morphologically normal; and (4) in the absence of chromosome segregation where kinetochore fibers have failed to form.
PARTIAL CHARACTERIZATION OF MOSQUITO LARVAE EXTRACT INDUCING DNA SYNTHESIS ALTERATIONS ON HUMAN MONONUCLEAR CELLS
Authors: Ronderos J. R. , Salas M. A. , Rimoldi O. J. , Finarelli G. 
Published: September 2002

AbstractA crude mosquito larvae and dialysed extract alters the mitotic rate of several epithelial cell populations in normal young and adult hepatectomized mice. A crude extract also showed a biphasic effect on the proliferation of human mononuclear cells (MNCs), either stimulating or inhibiting them depending on the dose applied. In the present paper, we assayed the effect of the dialysed mosquito larvae extract and two different protein fractions on human MNCs. Analysis of cell viability after culture indicated that the extract did not have toxic effects. Our results show a dual response of the MNCs to the dialysed, as well as to the protein fraction, with the highest molecular weight inhibiting or stimulating proliferation, depending on the dose applied. The protein fraction with the lowest molecular weight (range between 12–80kDa) showed only an inhibitory effect on cell proliferation.
MITOCHONDRIAL KINETICS DURING AMPHIBIAN ERYTHROPOIESIS RELATED TO HAEME SYNTHESIS
Authors: Cianciarullo Aurora M. , Bertho Álvaro L. , Meirelles Maria De Nazareth L. 
Published: September 2002

AbstractFlow cytometry, light and epifluorescence microscopies and transmission electron microscopy were used to follow the mitochondrial kinetics during amphibian erythropoiesis. A similar behaviour in response to the induction of anaemia was observed in the diploid Bufo ictericus and the tetraploid Odontophrynus americanus. A high cellular activity was observed ten days after haemolytic anaemia induced by phenylhydrazine, based on the higher Rhodamine 123 uptake by the erythroid cells. In addition, the more intense expression of the mitochondrial enzyme cytochrome oxidase, isocitrate and succinic dehydrogenases were cytochemically detected at this stage. This suggests that erythroid cell mitochondria, at this time, could be in a more active functional state than at other stages. In both species, mitochondrial plasticity was observed during cell maturation. A progressive loss of oxidation—reduction enzyme expression seemed to follow changes at the mitochondrial cristae morphology, from transverse to longitudinal form, mainly at the 20th day of recovery from anaemia, possibly related to a natural loss of function. The presence of these mitochondrial enzymes in mitochondrion‐like organelles also favours their participation in the haeme synthesis, although with a reduced expression, since this suggests the presence of a complete and active enzymatic complex in these modified organelles. This also supports the idea that all these organelles are mitochondria in distinct metabolic stages, and not mitochondrion‐like organelles or haemosomes, as proposed by some authors.
CELLULAR SIGNALLING AFTER IN VIVO HEAT SHOCK IN THE LIVER
Authors: Maroni Paola , Bendinelli Paola , Zuccorononno Cinzia , Schiaffonati Luisa , Piccoletti Roberta 
Published: September 2002

AbstractIn an experimental model of in vivo hyperthermia, we investigated the involvement of a number of signalling events in rat liver. We report that in vivo heat shock causes a powerful activation of c‐Jun N‐terminal kinase and p38 kinase but does not trigger poly(ADP‐ribose) polymerase cleavage, a signature event of apoptosis. Among the upstream regulators of the kinases, we show that stress‐activated protein kinase/extracellular signal‐regulated kinase/nitrogen‐activated protein kinase kinase 4 SEK1/MKK4 is not involved whereas MKK3 and/or MKK6 are activated. PAK activity displays a transient rise, whereas GCK does not change. PI3‐kinase activity increases in anti‐phosphotyrosine immunoprecipitates, suggesting a tyrosine kinase‐dependent induction mechanism, and the co‐immunoprecipitation of PI3‐kinase with p60 Src kinase supports the involvement of this latter. GSK3, which may act downstream to PI3‐kinase through AKT, undergoes hyperphosphorylation, thus playing a possible role in the protection from apoptosis and in the modulation of heat‐shock transcription factor activity.
EFFECT OF SERUM WITHDRAWAL ON THE PROLIFERATION OF B16F10 MELANOMA CELLS
Authors: Rodriguez‐Ayerbe Clara , Smith‐Zubiaga Isabel 
Published: September 2002

AbstractB16F10 murine melanoma cell proliferation was inhibited after 48h in medium with serum in the range 0.1 to 0.5% by volume. Cell viability was mostly retained, whereas cells completely deprived of serum died. Growth‐arrested cultures showed serum‐dependent suppression of DNA synthesis. The response was typically that of a ‘cell cycle freeze’, verified by flow cytometric distribution of cells. Consequently, serum deprivation did not lead to synchony when serum was restored to arrested populations. Furthermore, there was no change in PCNA expression in arrested cells.
INFLUENCE OF INHIBITORS OF CYTOSKELETON PROTEINS ON WATER EXCHANGE OF WHEAT ROOTS UNDER THE AFTER‐ACTION OF WATER STRESS
Authors: Volobuyeva O. V. , Khokhlova L. P. , Ganiyeva G. R. , Velikanov G. A. 
Published: September 2002

AbstractThe dynamics of water molecular state and transport in winter wheat (Triticum aestivum L.) of roots different resistance cultivars was studied by a biophysical method, Nuclear Magnetic Resonance (NMR), and a physiological method, Water‐Holding Capacity (WHC). The effective coefficient of water self‐diffusion (Deff), spin—spin relaxation times (T2) and WHC were measured after structural modification of cytoskeleton by colchicine and cytochalasin B after the action of water stress. New information about molecular mechanisms of water state and water transport regulation determined by the influence of dynamic cytoskeleton structure has been obtained. This is very important for the development of a fundamental theory of water exchange in plants, and for the ways of its optimization under conditions of environmental stress.
HELICOBACTER PYLORI VACUOLATING CYTOTOXIN (VacA) ALTERS CYTOSKELETON‐ASSOCIATED PROTEINS AND INTERFERES WITH RE‐EPITHELIALIZATION OF WOUNDED GASTRIC EPITHELIAL MONOLAYERS
Authors: Pai Rama , Sasaki Eiji , Tarnawski Andrzej S. 
Published: September 2002

AbstractIn previous studies, we demonstrated that Helicobacter pylori vacuolating cytotoxin (VacA) inhibits gastric epithelial cell proliferation and inhibits epidermal growth factor (EGF)‐activated signal transduction. Cell proliferation and migration, both essential for mucosal healing are dependent on the cell cytoskeleton. Other investigators demonstrated that VacA induces vacuolation of eukaryotic cells. Since in some cells, control of actin cytoskeleton involves GTP‐binding proteins of Rho family, in this study we examined whether VacA affects wound re‐epithelialization, cell cytoskeleton‐associated proteins Rho, Rac1 in a gastric epithelial (RGM1) cell monolayer wound model, and whether these changes correlate with vacuolation. VacA treatment significantly inhibited wound re‐epithelialization, cell proliferation vs control. VacA‐induced cell vacuolation strongly correlated with inhibition of wound re‐epithelialization. Furthermore, VacA reduced Rac‐1 protein expression and distribution, and C3‐mediated ADP‐ribosylation of Rho. These findings suggest that VacA may interfere with repair of gastric mucosal injury and ulcer re‐epithelialization by altering cytoskeleton‐dependent cell functions and signaling.