bluuebunny/crossref_metadata_2025 huggingface dataset:
Colchicine‐induced tubular, vesicular and cisternal organelle aggregates in absorptive cells of the small intestine of the rat. I. Morphology and phosphatase cytochemistry
Authors: Ellinger A. , Pavelka M.
Published: February 2012

Treatment of rats with colchicine administered intraperitoneally at a dosage of 0.5 mg per 100 g of body weight for 6 hr induces extensive accumulations of tubular‐vesicular and cisternal organelles in the absorptive cells of the small intestine. The formation of these organelle aggregates coincides with a reduction of microtubules and massive changes in the cellular organization including alterations of the Golgi apparatus and the plasma membrane. In most cases the accumulated tubules and vesicles contain a homogeneous electron‐dense matrix, the cisternae often having the character of rigid lamellae. The organelle aggregates mainly occupy apical cell portions subjacent to the terminal web as well as basal cellular regions close to the basolateral plasma membrane. Tubular‐vesicular as well as cisternal organelles react strongly for thiamine pyrophosphatase (TPPase), inosine diphosphatase (IDPase), acid phosphatase (AcPase) and trimetaphosphatase (TMPase). The staining pattern of TMPase differs from that of the other phosphatases in that the reaction is restricted to the colchicine‐induced tubular‐vesicular and cisternal aggregates, whereas TPPase, IDPase, and AcPase, respectively, also appear over Golgi stacks, multivesiculated bodies and plasma membrane. This phosphatase reactivity indicates the lysosomal character of the organelle aggregates.
The application of the nucleolar organizer region silver staining (AgNOR) to backscattered electron imaging (BEI)
Authors: Thiebaut F. , Rigaut J. P. , Feren K. , Reith A.
Published: February 2012

Until recently scanning electron microscopes were mainly used to observe surfaces. However, it has been proved that a backscattered electron detector can give an image (BEI) of the specimen's internal structure after heavy metal staining. In this paper, we report how we have applied the silver staining for NOR‐associated proteins to scanning electron microscopy, studying C3H10T1/2 cells in culture. This technique allows to localize, inside the nucleus, the nucleolar arrangement of AgNOR‐associated proteins. In BEI imaging, the silver staining shows several intranucleolar silver spot‐like deposits sometimes associated in “doublets” as on metaphasic chromosomes. These silver grains probably represent the fibrillar centre location, thought to be the interphasic counterpart of the NORs. However, these silver spot granules are more numerous during interphase.
Distribution of U3 snRNA in the nucleolus of CHO cells
Authors: Lacoste‐Royal G. , Simard R.
Published: February 2012

Localization of snRNA at the ultrastructural level was studied in the nucleolus of CHO cells by EM autoradiography. In conditions where snRNA U3 is the only RNA species labelled in the nucleolus, silver grains were largely found at the periphery, over the granular ribonucleoprotein component and the perinucleolar condensed chromatin; this enrichment was quantitatively significant. Inhibition of pre‐rRNA synthesis with actinomycin D did not alter the concentration or the distribution of U3 inside the nucleolus. The results are consistent with the demonstration that U3 is hydrogen‐bonded to 28S pre‐rRNA, and thus should be found in the granular compartment where 32S‐28S pre‐rRNA is assembled into 55s RNP.
S‐antigen immunoreactivity in retinal rods and cones and pineal photosensitive cells
Authors: Mirshahi M. , Faure J. P. , Brisson P. , Falcon J. , Guerlotte J. , Collin J.
Published: February 2012

The S‐antigen is a protein of photoreceptors, mainly known for its autoantigenic properties in mammals, which is widely distributed in the retina of vertebrates and in photoreceptor organs of invertebrates. Using three monoclonal antibodies specific for different epitopes of S‐antigen, this study complements our previous data on retinal rods and cones and presents new results on the photosensory cells of the pineal complex. Immunoreactivity was found in (i) retinal rods and cones, (ii) cone‐like and modified photoreceptor cells, and pinealocytes of the pineal organ of vertebrates, (iii) cone‐like photoreceptors of the frontal organ of the frog and of the third eye of the lizard. According to the species and the antibody used, some differences were found at the level of the cellular compartments of the pineal photoreceptor cells.
Modifications in the phosphorylation of cell proteins related to the expression of src gene in chicken embryo fibroblasts
Authors: Perrot D. , Dezelee P.
Published: February 2012

The possible physiological targets of pp60src in chicken embryo fibroblasts transformed by Rous sarcoma virus were looked for by a general screening of the modifications of phosphorylation of the major cell phosphoproteins. These modifications were analyzed quantitatively by SDS‐PAGE of total cell proteins on gradient gels, combined with a computerized densitometric evaluation of gel autoradiographies, using cells labeled with either [14C]‐amino acids or with [32P]‐phosphate. A large numbers of proteins, 37 out of the 68 studied, were found to be more phosphorylated in virally transformed cells. The determination of the phosphoamino acid content of proteins which were more phosphorylated in transformed cells and the study of the kinetics of protein phosphorylation in cells infected by a ts mutant, after a shift from the nonpermissive to the permissive temperature, showed that, among these proteins, five displayed a large increase in phosphotyrosine content and an early increase in phosphorylation after the temperature shift. These proteins of 36 K, 41 K, 46 K, 65 K and 280‐300 K doublet are therefore good candidates for being physiological targets of pp60src in the cell.
Effects of the vital DNA probe fluorochrome Hoechst 33342 on PtK cell chromatin
Authors: Gregoire M. , Hernandez‐Verdun D. , Bouteille M.
Published: February 2012

We investigated the effects of DNA labelling by fluorochrome Hoechst 33342, on chromatin distribution and transcription during a short‐term non‐toxic staining procedure which did not prevent the cell growth. By electron microscope examination we found chromatin condensation and nucleolar fragmentation just after the staining. Both effects appeared to be reversible 24h after staining; 48h afterwards, the morphological pattern was similar to that of control cells. The rate of RNA transcription was reduced at the end of staining, increased at 24h, and was comparable to the control at 48h. We also observed an effect on the cell cycle when the staining pasted 6h. Consequently, 24h after Hoechst vital staining, the effects on chromatin vanished whereas the cells remained fluorescent.
Effect of alpha‐difluoromethylornithine in lung metastases before and after surgery of primary adenocarcinoma tumors in mice
Authors: Klein S. , Miret J. J. , Algranati I. D. , de Lustig E. S.
Published: February 2012

The depletion of polyamines by alpha‐difluoromethylornithine (DFMO) treatment of mice after subcutaneous inoculation of adenocarcinoma M3 cells caused a remarkable inhibition in the growth rate of primary tumors as well as in the occurrence and number of lung metastases with a concomitant increase in survival time. Tumor‐bearing mice submitted to the surgical removal of primary tumors and then treated with alpha‐difluoromethylornithine also showed a significant reduction of lung metastases. In addition, a lower number of lung metastatic nodules correlated with decreased levels of polyamines in the same tissue. The described approach provides a useful experimental model for studies in human cancer therapy.
Relationship between growth inhibition and mitochondrial function in petite‐negative yeasts. II. Effects of central nervous system drugs upon pathogenic and non‐pathogenic Candida species
Authors: Marmiroli N. , Tedeschi F. , Sabatini M. A. , Truzzi G. , Ferrari C. , Puglisi P. P.
Published: February 2012

Six nervous system drugs which inhibited vegetative reproduction of S. cerevisiae arrested also mitotic division of C. utilis, C. albicans and C. tropicalis. Chlorpromazine and chlorpheniramine which proved to be the most effective, affected respiration and cytochrome biosynthesis. Electrophoretic bands with MW congruent to 100 K were faint in silver‐stained electrophoregrams of proteins from cells grown in the presence of a sub‐inhibitory concentration of chlorpromazine.
Transforming growth factors—an overview
Authors: Lawrence D. A.
Published: February 2012

Transforming Growth Factors (TGFs) are a sub‐group of a larger family of protein hormones. Two major types of TGF are currently known, alpha‐TGF and beta‐TGF. Biologically their most important property is to act synergistically to induce anchorage‐independent growth of target cells otherwise incapable of such growth. Since this growth parameter is well correlated with tumorigenicity in vivo, these factors may play a role in cancer development. Biochemically both alpha‐TGF and beta‐TGF have been well characterised in some types of cells and tissues. Their role in normal and neoplastic growth is actively studied.
Enhancement of glomerular permeability to anionic ferritin induced by kidney perfusion with collagenase
Authors: Schaeverbeke J. , Lalande H. Moreau , Geloso‐Meyer A. , Perichon M. , Borot‐Laloi C. , Cheignon M.
Published: February 2012

The role of collagen in ultrafiltration properties of the glomerular basement membrane (GBM) was tested after a single administration of bacterial collagenase, using native ferritin as a tracer which does not pass through the GBM under physiological conditions. Experiments were performed both in situ and with isolated kidneys. Increased permeability to ferritin occurs 6 hr following enzyme perfusion and becomes patent after 30 hr, numerous tracer molecules appearing in urinary space, without any readily observable changes either in distribution of fixed negative charges (as revealed by colloidal iron and polyethyleneimine) or in structural organization of the glomerulus. Selective permeability of the GBM is progressively restored so that ferritin is almost confined to capillary lumen one month after enzyme injection. We conclude that collagen plays an important part in restricting plasma protein filtration.
Permeability and changes in carbohydrate moiety in rat endometrial epithelium during oestrus as revealed by ruthenium red
Authors: de Mendoza M. V. Hurtado , Moreno F. J. , López‐Campos J. L.
Published: February 2012

We have used four different methods of ruthenium red (RuR) staining (RuR‐Lumen, RuR‐Glu, Glu/CB‐RuR and RuR‐OsO4) in order to study the permeability of the uterine epithelial cells of the rat during oestrus. The best results were obtained with the application of RuR‐OsO4, and this test was used for the statistical analysis. In addition, the dialyzed iron and diamine test (HID) techniques corroborated the nature of the acid glycoconjugate part of luminal surface of the uterine epithelium stained by the RuR. By means of the Thiéry technique we detected the presence of neutral glycoconjugates. These results, together with statistical analysis, lead us to suggest a) that the uterine epithelial cells present a greater permeability to RuR during early oestrus (Stage II) than during the later part (Stage III) and b) that sulphate group‐bearing glycoconjugates decrease in the course of the oestrus, whereas the neutral glycoconjugates remain constant.
In vitro multiplication and apparently indefinite subcultures of normal mouse resident peritoneal macrophages
Authors: Lombard Y. , Ulrich B. , Poindron P.
Published: February 2012

Multiplication of Balb/C mouse resident peritoneal macrophages was observed, when all the cells collected in the washing fluid of the peritoneal cavity were seeded in appropriate culture medium. This multiplication began only after the appearance of a confluent monolayer of flat cells, referred to as “mesothelial” cells. The macrophages produced passed from the “mesothelial” cell layer to the suspension and could be passaged indefinitely. Each culture underwent an identical cycle of events which always included the appearance of a confluent monolayer of “mesothelial” cells. The cells transferred were characterized by their ability to phagocytose yeasts, and by the presence of Fc receptors and cytoplasmic non‐specific esterases.
Effect of sodium butyrate on the complexity and the translation activity of hepatoma tissue‐cultured cell RNAs
Authors: Raymondjean M. , Tichonicky L. , Kruh J.
Published: February 2012

We have studied the effect of sodium butyrate on RNA populations and on the in vitro translation pattern of RNA from Hepatoma Tissue‐Cultured (HTC) cells. Since sodium butyrate inhibits cell growth we have used stationary cells as control. Molecular hybridization study of cDNA with polyadenylated RNAs shows that sodium butyrate induces the formation of additional 15% new RNA sequences, essentially in the class of abundant sequences and of sequences of intermediary abundance. This drug also decreases 5‐10 times the frequency of the sequences of intermediary abundance. One‐ and two‐dimensional polyacrylamide gel electrophoreses of the translational products of RNAs show that sodium butyrate induces or strongly increases the synthesis of 13 polypeptides and decreases the synthesis of 6 polypeptides, which is consistent with the effect of sodium butyrate on RNA populations and could result from the effect of this drug at both transcriptional and early post‐transcriptional steps. Electrophoretic analysis of the in vitro translation products of RNAs from cells submitted to sodium butyrate and transferred to a normal medium for various lengths of time shows that most of the polypeptides return to a normal pattern after a certain length of time which varies according to the polypeptide.
Osmium impregnation of the endoplasmic reticulum correlates with the functional status of prostatic secretory cells
Authors: Beaudry‐Lonergan M. , Thiery G. , Bergeron M.
Published: February 2012

The ultrastructure of prostatic secretory cells was studied with the osmium impregnation technique in order to determine if the ER reactivity, or its absence, and its three‐dimensional organization correspond to specific functions possibly hormono‐dependent. Thick sections (0.3 micron) of rat ventral prostate were made after a five‐day impregnation with osmium tetroxide and examined by standard transmission electron microscopy at 80 kV. Studies were performed in normal adult rats, between the 3rd and 26th day following castration and in castrated rats treated with 5‐alpha‐dihydrotestosterone. In normal rats the impregnation technique delineated three secretory cell types (dark, greyish and clear), representing various degrees of reactivity in ER cisternae; however, despite this quantitative variation, they had similar morphological characteristics. In a longitudinal section, the ER network appeared to be made of saccules running parallel along the length of the cell and forming whorl‐like patterns around the nucleus. Comparison of sections taken at various angles suggests that the ER network is made of concentric parallel saccules extending from the base to the apex of the cell and encircling the nucleus and the Golgi apparatus like a large multilayered cylinder. Whereas in dark cells the Golgi apparatus contained mostly clear vesicles, it was always heavily impregnated in clear cells. Noteworthy, osmium deposits were rarely observed on the nuclear envelope of secretory cells but were always present in basal cells. After castration, secretory cells became progressively cubic and the most conspicuous cytoplasmic change was observed in association with the ER. The Golgi apparatus decreased markedly in volume and became heavily stained with metallic osmium.(ABSTRACT TRUNCATED AT 250 WORDS)
Three‐dimensional analysis of fibrillar centers and associated chromatin in the nucleolus of human oocytes in primordial follicles
Authors: Cataldo C. , Souchier C. , Vasserot M. , Calisti A. , Vagner‐Capodano A. M. , Stahl A.
Published: February 2012

The intranucleolar localization of fibrillar centers and their relationships with nucleolus‐associated chromatin were determined in stereopairs of human oocyte nucleoli obtained by computer reconstruction of serial sections. This study showed that there was no numerical relationship between the number of fibrillar centers and the number of chromosomal NORs. The three‐dimensional reconstruction demonstrated that the majority of fibrillar centers was directly connected with the nucleolus‐associated chromatin.
Modulation of membrane receptor endocytosis by chemical effectors of membrane fluidity
Authors: Elguindi I. , Redziniak G. , Metezeau P. , Meybeck A. , Goldberg M. E.
Published: February 2012

Several chemical effectors were used to induce changes in spleen B cell membrane fluidity. Membrane fluidity was monitored by fluorescence polarization analysis of the hydrophobic probe 1,6‐diphenyl‐1,3,5‐hexatriene (DPH) and cell viability was checked not to be affected by the treatments. Membrane immunoglobulin (Ig) endocytosis by the living B cells with modified or unmodified membranes was quantitatively measured by flow cytometry, using a previously described method (Métézeau et al., 1982, 1984). The kinetics of endocytosis of membrane Ig was not affected by chemical effectors increasing membrane fluidity. On the contrary, increasing membrane microviscosity resulted in the slowing down and eventually the blocking of membrane Ig endocytosis. It is suggested that a step depending on membrane microviscosity is involved in the process of endocytosis; this step may become rate limiting when membranes are artificially rendered or naturally become (i.e. for pathological or particularly differentiated cells) more viscous.
The use of bacteria as probes for lectins in preparations of solubilized human tonsil cell membranes
Authors: Ralapati S. , Teodorescu M.
Published: February 2012

In earlier work we have shown that some bacteria bind naturally to lymphocyte subpopulations and that this binding may be due to lectin‐carbohydrate interactions. Here we determined the possibility of using bacteria to probe for these lectins in solubilized tonsil cell membrane preparations. Since lectins are capable of agglutination, we determined the ability of human tonsil cell membrane extract (TCME) to agglutinate bacteria. We used Escherichia coli strain YS57 which does not bind to human lymphocytes and a mutant strain derived from it, E. coli UI 2023, which binds to about 50 percent of human lymphocytes. The UI 2023 was agglutinated while the YS57 was not; this agglutination was not due to antibodies or DNA. When E. coli UI 2023 was treated with periodate, it lost its ability to be agglutinated. The agglutination of E. coli UI 2023 was not blocked by any of the monosaccharides and disaccharides used but was blocked by the E. coli LPS, more specifically, by its carbohydrate moiety. Also, the E. coli UI 2023 absorbed the agglutinating factor while its parental strain, YS57, did not. Sodium dodecylsulfate‐polyacrylamide gel electrophoresis of TCME after absorption with bacteria showed that a band around 67kD was absent in the TCME absorbed by E. coli prevented the absorption by E. coli UI 2023 whereas Na2IO4‐treated LPS did not. In addition, tonsil cell membrane was radioiodinated before obtaining the TCME; sodium dodecylsulfate‐polyacrylamide gel electrophoresis of the radioiodinated TCME recovered after elution from E. coli UI 2023, but not from E. coli YS57, showed again a band around 67 kD.(ABSTRACT TRUNCATED AT 250 WORDS)
Morphometrical and immunocytochemical studies on rat pancreatic acinar cells under control and experimental conditions
Authors: Bendayan M. , Bruneau A. , Morisset J.
Published: February 2012

Process of amylase and chymotrypsinogen secretion by acinar cells has been studied applying morphological and biochemical approaches. Three conditions were investigated; resting (fed control), cholinergic stimulation and fasting. Morphometrical evaluations have shown that under stimulation, the volume density of zymogen granules decreases drastically while that of the Golgi apparatus increases. This may result from the enhancement in protein processing and the rapid discharge. Quantitation of amylase and chymotrypsinogen immunolabelings present over the cellular compartments has shown that there is no difference in the intensities between tissues from control and stimulated animals. These results imply that total amounts of protein processed by the Golgi apparatus are markedly enhanced primarily because of the increase in size of the organelle, the amounts of protein processed per unit surface remaining unchanged. Under starvation where reduction of secretion occurs, there is a significant decrease in the volume density of the Golgi apparatus but no variation in that of the zymogen granules. However, the morphological aspect of these was markedly altered since many of them present an electron luscent periphery which was devoid of immunolabeling for amylase and chymotrypsinogen. Quantitation of amylase and chymotrypsinogen immunolabelings has shown significant diminution for both enzymes. In both experimental conditions, the volume density of lysosomes was enhanced, however in none of these conditions evidence of crinophagy was observed. The morphometrical and immunocytochemical results were consistent with those obtained from biochemical determination of amylase and chymotrypsinogen contents in tissues. Correlations between results obtained from morphometric and immunocytochemical studies were made leading to a better understanding of the cellular secretory activity during experimental conditions.
Actin content and organization of microfilaments in primary cultures of mouse embryonic fibroblasts (in vitro ageing)
Authors: Van Gansen P. , Pays A. , Malherbe L.
Published: February 2012

Actin distribution in serially passaged embryonic mouse fibroblasts has been visualized by the anti‐actin‐PAP method; the organization of the microfilaments has been observed by electron microscopy (SEM and TEM). Four successive actin patterns have been identified: early (few well‐organized bundles of microfilaments), middle‐aged (many well‐organized bundles and patches around the nucleus), late (numerous ill‐organized filamentous structures and diffuse perinuclear‐actin) and “senescent” (heavy packs of short microfilaments around the nucleus). All the observed actin‐positive filaments were disrupted by cytochalasin B treatment. The cytoplasmic actin complex was cell‐age and not cell‐size‐dependent; it behaved differently from the cytoplasmic microtubular complex to serially subcultivated fibroblasts. Measurements of the cell‐protein content (Lowry's method) and SDS‐polyacrylamide gel electrophoresis (Laemmli's method) have been performed in the successive population doubling levels (PDL) of the primary cultures. Triton‐insoluble actin increased in parallel with total protein and reached about 4% of the total proteins in all the PDLs. Triton‐soluble actin also increase at the beginning of the middle‐aged period (generally 6 PDL) and another in declining cultures (generally 10 PDL). Total actin amounted to about 8% of the total proteins in early fibroblasts, to about 16% at the beginning of the middle‐aged period and to about 20% in the declining terminal cultures. Taking into account all the known characteristics of subcultivated primary cultures, we tentatively consider the evolution of the fibroblasts as an in vitro differentiation followed by true in vitro senescence in the declining cultures. Regarding the cytoplasmic actin‐complex, senescence would be characterized by a sharp increase in soluble actin, an unbalanced ratio between soluble and insoluble actin and an impairment of the ability of the microfilaments to form well‐organized bundles.
Control of the blastemal cell cycle by the peripheral nervous system during newt limb regeneration; continuous labeling analysis
Authors: Boilly B. , Oudkhir M. , Lassalle B.
Published: February 2012

Forty‐eight and 96 hr 3H‐thymidine continuous labeling was analyzed on denervated mid‐bud limb blastemas of Pleurodeles waltlii M. In innervated blastemas, 92 to 95% of mesenchymal cells are cycling; denervation provokes an early exiting from the cycle in G0‐1(+ 15% of non‐cycling cells for a 6‐day denervation, + 20% for an 8 day denervation) and an elongation of the G1 phase. For epidermis only 25% (48 hr labeling) to 53% (96 hr labeling) of cells are cycling in innervated blastemas; denervation strongly decreases this percentage (+ 40% of non‐cycling cells for a 6‐day denervation, + 60% for an 8‐day denervation). As for mesenchyme, denervation also lengthens the G1 phase of epidermal cells. So our results contradict the conclusion of other authors claiming a G2 blockage. They account for the fall in proliferation indices and the arrest of regeneration after denervation. Finally, they show that the cell cycle of regeneration cells is controlled by the neurotrophic factor.
Three‐dimensional graphical reconstruction from HVEM stereoviews of biological specimens by means of a microcomputer
Authors: Bonnet N. , Quintana C. , Favard P. , Favard N.
Published: February 2012

A microcomputer reconstruction technique has been developed in order to permit a larger exploitation of stereomicroscopy. The microcomputer facility consists of a digitizing tablet, a microcomputer, a graphics terminal, a graphics plotter and a printer. The technique has been applied to the study of HVEM stereopairs, performed by recording two images of the same area of a specimen (thick section of araldite‐embedded leech ganglion neurons), tilted relative to the beam axis through an angle 0/20 degrees. Coordinates of N conjugate points of interest, expressed in a common reference system were obtained with the help of a digitizing tablet and the misorientation between the two images was determined by a method based on a least square technique. New projections of the object on different planes are provided by the microcomputer facility. Also the microcomputer method permits to obtain new stereopairs drawings, in various orientations and slices from a three‐dimensional reconstruction of the object oriented in any direction in space. The method permits to obtain computed anaglyph drawings, printed here, which are stereoviews of the same object.
Application of computer‐assisted image analysis for studying viral structures
Authors: Rudolph M. , Pleissner K. P.
Published: February 2012

The application of CAIE has been shown to be useful for analyzing the structures of RNA viruses. Critical assessment of this method is essential for the selection of the micrographs of viruses. In our experience this procedure was helpful for resolving some questions concerning virus morphology.
Mechanism of inhibition by lithium of sodium transport in the toad bladder
Authors: Herrera F. C. , Beauwens R. , Crabbe J.
Published: February 2012

Lithium transport across the urinary bladder of Bufo marinus has been studied by means of the short‐circuit current technique, as well as unidirectional ion flux measurements. Exposure to lithium of the epithelial (mucosal) surface of this preparation led to a slow, progressive decrease of ion transport, with increasing discrepancy between short‐circuit current and lithium influx; in fact there was still an appreciable lithium influx across bladder exposed to amiloride even though short‐circuit current was suppressed. Ohmic conductance and sodium efflux barely increased under these circumstances. Upon replacement of lithium by sodium on the epithelial side, the preparations recovered slowly indeed, and residual lithium could be detected in bladder tissue for more than 2 hr while the rate of sodium extrusion at the basal‐lateral cell border was slowed down. Recovery from exposure to lithium was accelerated by vasopressin and amphotericin, both of which facilitate sodium entry at the apical border of the epithelium. Thus the lasting deleterious influence of lithium on sodium transport might result from the fact that this ion, once trapped in the cytoplasm, closes the sodium channels.
Steroid hormone receptors: intracellular distribution
Authors: Gasc J. M. , Baulieu E. E.
Published: February 2012

Recent reports, both biochemical and morphological, have challenged the widely accepted two‐step model of steroid hormone action. This model proposed that steroid hormone receptors existed under two different forms: the unliganded receptor in the cytoplasm and the hormone‐bound receptor complex in the nucleus. A nuclear translocation mechanism was hypothesized as a necessary link between the two forms. In contradiction with this model, new studies have concluded to the absence of receptor in the cytoplasm and its presence in the nucleus under all hormonal conditions, thus rendering the hypothetical nuclear translocation unnecessary. In this review, we discuss how our concept of the mechanism of action of steroid hormone ought to be revised in the light of the new data.
Studies on DNA polymerases of Xenopus laevis oocytes: subcellular distribution and physical association of DNA polymerase alpha inside the nucleus
Authors: Solari A. , Zourgui L. , Carvallo P. , Tarrago‐Litvak L.
Published: February 2012

The localization of DNA polymerases in Xenopus laevis oocytes and eggs was studied. Oocytes have a high level of DNA polymerase alpha activity detected exclusively in the nuclei, while mitochondria contain all the DNA polymerase activity of the gamma type. No DNA polymerase beta activity is present in the nuclear fraction. Moreover, the beta activity is not present in unfertilized eggs. In oocytes, DNA polymerase alpha is weakly bound to the nucleoplasm. The leakage of the enzyme from whole nuclei can be prevented using polyvinylpyrrolidone, a nuclear pore sealing agent.
Folded chromosome in Bacillus subtilis after rifamycin treatment
Authors: Guillen N. , Bohin J. P.
Published: February 2012

Bacterial DNA is organized as a compact nucleoid whose structure is maintained by membrane—DNA, protein—DNA and RNA—DNA interactions. We investigated the effect of the transcription inhibitor rifamycin on the structure of the nucleoid in B. subtilis. Decrease of nucleoid compactness and loss of DNA superhelicity were correlated with DNA transcription arrest, both in the wild‐type and in a rifamycin‐resistant strain. Moreover, the phospholipid content of the nucleoid does not change upon rifamycin treatment.
Locus ref(2)P of Drosophila melanogaster. I. Cytogenetic localization of ref(2)P
Authors: Nakamura N. , Gay P. , Contamine D.
Published: February 2012

The ref(2)P gene is a Drosophila gene which acts on Sigma virus multiplication. From recombination experiments the ref(2)P gene was located between hk and pr. This location was confirmed by the study of eight chromosomic aberrations, without ref(2)P gene activity, obtained following × irradiation. From the cytological study of three of these chromosomes and from the study of the ref(2)P gene activity of chromosomic aberrations obtained by other workers in the same region of the second chromosome, the ref(2)P gene was cytologically located in 37E3‐37F3.
Molecular forms of acetylcholinesterase in mammalian smooth muscles
Authors: Taxi J. , Rieger F.
Published: February 2012

A comparative study of the molecular forms of acetylcholinesterase (AChE) was made in various smooth muscles (intestine, vas deferens, ciliary body, iris, nictitating membrane retractor, ureter, arteries, anococcygeus muscles) of some mammals (cat, guinea‐pig, rat, rabbit, mouse), seeking for a correlation between the presence of 16 S (asymmetric, tailed) form of AChE in smooth muscles and their type of innervation defined by morphological criteria, as well as by the nature of the main neurotransmitters involved in their neuroeffector junctions. Contrary to previous assertions, many smooth muscles contain 16 S AChE, although all those examined here exhibited a proportion clearly less than that of striated muscles. There are large species‐specific and individual variations in the percentage of 16 S AChE. The highest percentages of 16 S AChE were found in ciliary and iris muscles, which are provided with an individual (= multiunit) cholinergic innervation. The vas deferens muscles, which are also individually, but noradrenergically innervated contain practically no 16 S AChE. In the muscles having a fascicular (= unitary) innervation, the differences are striking: 16 S AChE is in rather high amount in intestine muscle layers, whereas it is very low or virtually absent in ureter or arterial muscles. Thus, the type of innervation is not clearly involved in the amount of 16 S AChE present in smooth muscles. As for the nature of neurotransmitter a clear correlation exists only in the case of individual innervation, in which only one neurotransmitter is involved or largely predominant.
Primary rat cardiac cell culture: diet of the mother rats as a determinant parameter of cardiomyoblast production from neonates
Authors: Grynberg A. , Degois M. , Guenot L. , Athias P.
Published: February 2012

Two populations of Wistar rats from the same strain were fed two commonly used commercial chows. The yields of myocardial cells for primary culture obtained from neonatal rats in these 2 populations were significantly different. This effect is strickly caused by diet used during pregnancy and is quickly reversible from one pregnancy to the following one in the same females. This diet effect is limited to the yield in cardiomyoblasts and cultures were not found different after 5 days in the same medium.
Membrane tubulin
Authors: Stephens R. E.
Published: February 2012

Tubulin has been identified as a membrane component of nerve synaptosomes and myelin, plasma membranes of platelets, thyroid, and tissue culture cells, brain and liver coated vesicles, mitochondria, and in cilia but not flagella of certain molluscs. Membrane tubulin can differ from cytoplasmic forms in isoelectric point, non‐polar amino acid substitutions, lack of carboxy‐terminal tyrosine, carbohydrate content, and selective ability to reassociate with lipids. This tubulin may function as an attachment site for binding vesicles or plasma membranes to cytoplasmic microtubules, as a source of precursor tubulin at the growing tips of axonemes, or as a component of signal transduction in sensory cilia.
p53 and transformation by SV40
Authors: O'Reilly D. R.
Published: February 2012

The large T antigen of SV40 is able to immortalize and transform primary and established cells in culture, and can, at least in certain cases, confer a tumorigenic phenotype on the infected cell. T antigen has been shown to induce cellular DNA synthesis in the infected cell and this activity is likely to be instrumental in T antigen mediated oncogenesis. A property of T antigen which may be of paramount importance to its oncogenic and mitogenic activities is its ability to specifically bind and stabilize the cellular protein p53. p53 has been implicated in the control of the passage of the cell from G0 arrest to G1 and S phase. Furthermore, altered p53 expression is strongly associated with various phenotypes of the transformed state, and p53 has been identified as an immortalizing oncogene. Thus it is possible that p53‐fixation by T antigen is responsible for its transforming potential. In this article, the transforming activities of T antigen and p53 are reviewed, and the possible relevance of p53‐binding to T antigen‐induced transformation is discussed.
Autoradiographic detection of the earliest stage of [3H]‐uridine incorporation into the cow embryo
Authors: Camous S. , Kopecný V. , Fléchon J. E.
Published: February 2012

Cow embryos, obtained from superovulated heifers on days 3 and 4 after oestrus, were cultured for 20 min in Ménézo's complete culture medium (B2), enriched with 200 microCi/ml of 5‐[3H]‐uridine. Semi‐thin Epon sections of this material were investigated by autoradiography for sites of RNA synthesis. It was found that 5‐[3H]‐uridine was incorporated into the nucleoplasm and nucleoli only at the end of the 8‐cell stage. This suggested that synthesis of hnRNA and rRNA occurred from this stage onwards. Ultrastructural studies were performed on these embryos as well as on other non‐incubated 4‐cell embryos recovered on day 2. The transformation of dense fibrillar primary nucleoli into functional reticulated nucleoli appeared sooner in the development of cow embryos than in other mammalian species hitherto studied and took place generally during the 8‐cell stage. An unusual step in this transformation was represented by the development of a single vacuole in nucleoli at the beginning of this stage (day 3 post‐oestrus).
Biochemical and ultrastructural findings in Epstein‐Barr virus‐transformed lymphoid cell lines from type 1 Gaucher disease
Authors: Maret A. , Salvayre R. , Livni N. , Icart J. , Vuillaume M. , Douste‐Blazy L.
Published: February 2012

Lymphoid cell lines established by Epstein‐Barr Virus (EBV)‐transformation of peripheral blood B‐lymphocytes from patients affected with type 1 Gaucher disease showed a severe deficiency of glucosylceramide‐beta‐glucosidase activity (residual activity around 15%‐30% of control activity). Ultrastructural investigations showed, in these lymphoid cell lines from type 1 Gaucher disease, the presence of numerous membrane‐bound inclusion bodies characteristic of Gaucher cells.
Evolution of the rat oocyte nucleolus during follicular growth
Authors: Antoine N. , Lepoint A. , Baeckeland E. , Goessens G.
Published: February 2012

The ultrastructural evolution of the nucleolus was followed during follicular growth by means of a silver staining procedure. The oocyte nucleolus in the primordial and primary follicles consists of strands of dense fibrillar silver‐stained component and aggregates of granules which are devoid of silver grains. Small fibrillar centres are also recognized and appear to have less silver stainability. At the secondary follicle stage, a new nucleolar component appears in the reticulated oocyte nucleolus. This component is devoid of silver grains. During follicle growth, at the antral follicle stage, this new component seems to fuse and the nucleolus becomes constituted of a compact homogeneous mass which exhibits a vacuole at the end of the oocyte maturation. The results obtained suggest that this nucleolar mass is essentially made of proteins and particularly of acidic proteins.
The three‐dimensional ultrastructure of interphasic and metaphasic nucleolar argyrophilic components studied with high‐voltage electron microscopy in thick sections
Authors: Ploton D. , Beorchia A. , Menager M. , Jeannesson P. , Adnet J. J.
Published: February 2012

The three‐dimensional structure of the nucleolar argyrophilic components was studied by recording stereo‐pairs of tilted thick sections—0.5‐2 microns thick—observed with 200 and 300 kV high‐voltage electron microscopy (HVEM). Using a very specific silver staining method, the argyrophilic components were stained with a high contrast relatively to the unstained background, thus allowing their study with a high resolution within thick sections. This study was performed on compact nucleoli (of HL60 and K562 cells), on reticulated nucleoli (of human breast cancerous cells) and on metaphasic nucleolar organizer regions (NORs). In compact nucleoli argyrophilic components show a ‘knotted rope‐like’ structure in which knots are constituted of one central fibrillar centre surrounded at some distance by loops of the dense fibrillar component and in which the rope is constituted of dense fibrillar component. In reticulated nucleoli silver deposits are confined to the surface of the nucleolonema as several strands twisted at the periphery of the fibrillar component. During metaphase some NORs get a characteristic crescent‐shaped structure disposed at the periphery of some chromosomes.
Effect of tubulozole, a new synthetic microtubule inhibitor, on the induction of casein gene expression by prolactin
Authors: Servely J. L. , Geuens G. M. , Martel P. , Houdebine L. M. , de Brabander M.
Published: February 2012

Colchicine and related drugs are known to inhibit milk secretion. They are also able to prevent stimulation of casein and DNA synthesis by prolactin in the mammary gland. The present report reports data obtained with tubulozole, a new antimitotic drug. Tubulozole C added to culture medium of isolated rabbit epithelial mammary cells strongly inhibited their multiplication. Simultaneously, at a concentration of 1 microM, it prevented almost completely the induction of beta‐casein mRNA. Induced cells were rapidly deinduced by addition of the drug to the medium. A similar inhibition was observed when the induction was obtained with prolactin alone or with its two stimulators insulin and glucocorticoids. Tubulozole T, an isomer of tubulozole C which is known to be ineffective in disrupting microtubules, did not alter prolactin actions. These data and those obtained with other tubulin‐binding drugs strongly suggest that the integrity of microtubules is required for prolactin to deliver its message to the mammary cell.
Cytochemical localization of thiamine pyrophosphatase and nicotinamide adenine dinucleotide phosphatase activities in rat epiphyseal chondrocytes
Authors: Velasco A. , Hidalgo J.
Published: February 2012

Two phosphatase activities, which have been reported to be associated with the Golgi apparatus in several cellular types, have been cytochemically demonstrated in rat epiphyseal cartilage. This was the case for thiamine pyrophosphatase (TPPase) which was detected in Golgi trans face cisternae and also in nascent or immature secretory granules of chondrocytes. beta‐Nicotinamide adenine dinucleotide phosphatase (beta‐NADPase), on the other hand, was localized mainly in the endoplasmic reticulum region of both proliferative and hypertrophic chondrocytes. Most of the beta‐NADPase reaction was shown to be associated with the cytoplasmic side of the rough endoplasmic reticulum membranes and also partially dispersed throughout the cytosol background. We suggest that beta NADPase in chondrocytes could be an enzyme with different properties from that described in other secretory cells.
Fibronectin (FN) localizations in mitochondria‐rich cells of frog epidermis
Authors: Denefle J. P. , Lechaire J. P. , Zhu Q. L.
Published: February 2012

Indirect immunoperoxidase detection of fibronectin (FN) in the ventral frog epidermis showed that only one type of epidermal cell, the mitochondria‐rich cells (MRC), was FN‐detected. FN was found in MRC having rounded, flask‐like and intermediate shapes, located at different levels of the epidermis between the stratum germinativum and the stratum corneum. These cells contained cytoplasmic FN particularly in the form of small granules. Our results support the view that MRC differ from other epidermal cells in their in vivo FN localizations.
Differential expression of alkaline phosphatase and ATPase activities in human colon carcinoma cell line HT‐29.18 during differentiation
Authors: Le Bivic A. , Arsanto J. P.
Published: February 2012

The expression and cytochemical localization of alkaline phosphatase and Na+‐pump sites were investigated in the human adenocarcinoma cell line HT‐29.18 during differentiation. In the undifferentiated state, HT‐29.18 cells expressed ATPase activity on plasma membrane whereas they displayed no alkaline phosphatase activity. In differentiated HT‐29.18 cells, strong alkaline phosphatase activity was present on the apical membrane, whereas ATPase activity was restricted to the basolateral membrane. Intra‐ and intercellular lumina (cysts) observed in undifferentiated cells were devoid of both enzyme activities. In differentiated cells, cysts bearing well developed microvilli were strongly positive for alkaline phosphatase activity, while this activity seemed to be lacking in cysts without microvilli. ATPase activity was not found in either type of structure. Finally, HT‐29.18 differentiated cells expressed, at pH 9.0, a p‐nitrophenylphosphatase activity six‐fold greater than that of undifferentiated cells.
Ultrastructural localization of actin in the intermediate lobe of rat hypophysis
Authors: Kondo H.
Published: February 2012

The localization of actin in the cells of the pars intermedia of rat hypophysis was studied by means of the polyethylene glycol (PEG) embedding and subsequent de‐embedding method together with FITC and IgG‐colloidal gold immunolabelling techniques. Actin immunofluorescence was detected to be punctate throughout the entire cytoplasm, except for the nuclear region. In electron microscopy actin gold‐labelling was localized on portions of microtrabeculae in close association with the secretory granules, but not within the secretory granules themselves. This close association of actin with the secretory granules strongly suggests the involvement of the contractile protein in the cellular secretory process. Several restrictions due to the PEG‐method itself are also discussed to interpret clearly immunoelectron microscope images from the embedment‐free sections.
Cytoskeleton of the unfertilized sea urchin egg
Authors: Foucault G. , Raymond M. N. , Pudles J.
Published: February 2012

Unfertilized Paracentrotus lividus egg cytoskeleton is prepared by mild, nonionic detergent extraction at 4 degrees C in buffer systems containing either 2‐methyl‐2,4‐pentanediol (hexylene glycol) or glycerol. These extractions allow the isolation of cytomatrices that maintain the egg form and are 70‐80 micron in diameter. DNase inhibition assays show that actin is in polymerized form in these cytomatrices. Ultrastructural observations reveal that the cytoskeletons are made up essentially of 2 categories of filaments, 7‐8‐nm and 2‐4‐nm in diameter, respectively. After heavy meromyosin labelling, short, radiating actin filaments are seen in the cortical region, while longer actin filaments are found in the internal region of these cytomatrices. The 2‐4‐nm filaments of still unknown biochemical nature are organized in a meshwork. In contrast to results found with fertilized eggs, bundles of actin filaments and microtubules are absent; 8‐13‐nm filaments are not detected.
Human autoimmune serum antibodies against gag gene p30 retroviral protein also react with a U1‐SnRNP 68K comigrant protein
Authors: Rucheton M. , Graafland H. , Valles H. , Larsen C. J.
Published: February 2012

Using Immunoblotting procedure, we showed that autoimmune human antibodies reacting with mouse retrovirus gag‐p30 also reacted with a HnRNP 68 Kd protein. Since U1‐SnRNP 68 K and p30‐gag proteins show 40% homology, the detected 68 Kd protein is likely to be the U1‐RNA 68 K.
Nuclear antigens differentially expressed during early development of Drosophila melanogaster
Authors: Garzino V. , Moretti C. , Pradel J.
Published: February 2012

To obtain specific immunological probes for studying molecular events involved in gene activation during early development of Drosophila, we have produced monoclonal antibodies directed against nuclear proteins differentially expressed in time and space during embryogenesis. Twenty‐five antibodies against nuclear antigens detected after the onset of zygotic genome transcription were obtained. These antigens have been distributed into six categories depending on their reactivity in dot‐blot, in Western‐blot and in immunofluorescence on embryo frozen section assays. Six antigens (fifth and sixth categories) are stage‐, but not tissue‐specific and are present in all nuclei of the embryo after the blastoderm stage. Ten antigens, the third and fourth categories, did not react on immunofluorescence and have not been characterized for a possible tissue specificity. Antigens of the first and second categories are stage‐ and tissue‐ specific. Two of them are of particular interest. The first (250 kd, recognized by the monoclonal antibody GB7) is preferentially expressed in nuclei of the ventral nerve cord, whereas the other (65 kd, recognized by the monoclonal antibody LA9) is located in nuclei of the gut and associated structures.