bluuebunny/crossref_metadata_2025 huggingface dataset:
Red cell ageing: phagocytosis and life‐span of young and old erythrocytes fractionated by centrifugation
Authors: Bladier D. , Vassy R. , Perret G. , Cornillot P. , Monsigny M.
Published: February 2012

Young and old red blood cells, separated by centrifugation on the basis of differences in cell density, were submitted to phagocytosis by either autologous human alveolar macrophages or syngeneic murine bone‐marrow macrophages. Young cells adhere to macrophages, but to a much smaller extent than old ones. The influence of both type and quality of the separation procedure on the differences observed between the two erythrocyte subpopulations is discussed in the light of the half‐life times of murine young and old red blood cells. Fractionation according to age was obtained following the method of Murphy (1973) and glutamate oxalo‐acetate transaminase activity was measured and used as an indicator of both cell age and separation.
Galactose‐specific adsorptive endocytosis: an ultrastructural qualitative and quantitative study in cultured rat hepatocytes
Authors: Deschuyteneer M. , Prieels J. P. , Mosselmans R.
Published: February 2012

Using galactosylated bovine serum albumin coupled to colloidal gold (galBSA‐CG) as a probe, the receptor‐mediated endocytosis pathway has been analyzed qualitatively and quantitatively at the ultrastructural level in cultured rat hepatocytes. The results showed that galBSA‐CG was specifically recognized by the asialoglycoprotein receptor of the hepatocytes, thus confirming biochemical findings. The probe was preferentially bound in coated pits of the cell surface. When bound elsewhere on the plasma membrane, it apparently moved towards coated regions. In both cases, it was then internalized via coated vesicles. The galBSA‐CG passed through pleiomorphic tubular structures and in endosomes, a pool of smooth‐surfaced vesicles of various size (50‐350 nm), before transiently accumulating in multivesicular bodies. The latter then fused with lysosomes where the glycoproteinic moiety of the probe was degraded, as judged by the flocculated aspect of the accumulated gold particles. About 10% of the internalized ligand was recycled back to the cell surface via secreting vesicles containing lipoprotein‐like particles without having apparently passed through lysosomes, which suggests the existence of a pre‐lysosomal sorting mechanism of the endocytosed material. Functional recovery of the morphologically restored biliary polarity of hepatocytes in culture was indicated by the fact that galBSA‐CG finally appeared in the reconstituted bile canaliculi.
Estimating glycoprotein carbohydrate chain structures by lectin reactivities in polyacrylamide gels
Authors: Nicolson G. L. , Irimura T.
Published: February 2012

Complex mixtures of cellular glycoproteins contain a myriad of different carbohydrate chains that cannot be easily analyzed without rigorous purification of each individual glycoprotein. We have analyzed the carbohydrate chains in complex mixtures of cellular glycoproteins by separation using sodium dodecyl‐sulfate polyacrylamide gel electrophoresis and interacting the gels with several 125I‐labeled lectins. By use of in situ chemical modifications of the glycoproteins after their electrophoretic separation together with the known carbohydrate‐binding specifities of several lectins, it has been possible to estimate glycoprotein carbohydrate chain structures. As an example we have examined the cellular glycoproteins of a ovary‐colonizing metastatic variant of B16 melanoma and report the types of carbohydrate chains that are found on various melanoma glycoproteins.
Liver connective tissue cells isolated from human schistosomal fibrosis or alcoholic cirrhosis represent a modified phenotype of smooth muscle cells
Authors: Borojevic R. , Vinhas S. A. , Monteiro A. N. , Domont G. B. , Zyngier F. R. , Grimaud J. A.
Published: February 2012

Hepatic connective tissue cells associated with schistosomal fibrosis and alcoholic cirrhosis were studied in vitro. Primary cell lines were isolated from all biopsies: they were identified as specific homogeneous cell populations, named liver connective tissue cells (LCTC). They were recognized as analogous to smooth muscle cells, different from true fibroblasts by morphological and physiological criteria. The proliferative capacity of LCTC is directly proportional to the degree of fibrosis in hepatic tissues. LCTC are able to secrete type I, III and IV collagen, fibronectin, laminin and amyloid P component. Their relationship with specific pathology of intrahepatic vascular tree in schistosomiasis is hypothesized.
Increase of globin RNA synthesis induced by phosphatidylserine liposomes in isolated erythroleukemic cell nuclei. Morphological and functional features
Authors: Cocco L. , Gilmour R. S. , Maraldi N. M. , Martelli A. M. , Papa S. , Manzoli F. A.
Published: February 2012

The effect of phospholipid vesicles on chromatin structure, protein composition and globin RNA synthesis has been analysed in nuclei isolated from murine erythroleukemia cells. In terms of chromatin organisation, PC vesicles with neutral surface charge do not affect the structure of chromatin fibres, whereas negatively charged PS vesicles induce chromatin decondensation to a great extent. Indeed the fibres appear uniformly dispersed lacking also the perinucleolar heterochromatin. These morphological features are accompanied by depletion of lysine‐rich histones H1 and H1(0) and of histone‐like protein A5, due to PS liposomes. Functionally, PS vesicles induce enhancement both of total RNA and specific mRNA synthesis, as analysed by in vitro transcription of beta globin gene. On the contrary, PC vesicles do not seem to affect significantly total RNA and globin mRNA synthesis. These observations fit well with previous data obtained in other experimental systems, and support both the use of these molecules as probes for chromatin structure and function and their possible involvement in transcriptional events.
Re‐evaluation of the site of transcription in Ehrlich tumour cell nucleoli
Authors: Thiry M. , Lepoint A. , Goessens G.
Published: February 2012

Recent electron microscopic immunolocalization studies (Scheer and Rose, 1984) indicated that RNA polymerase I is located in, and probably confined to, the fibrillar centres of the nucleoli. This conclusion appears to be in contradiction to previous autoradiographic studies reporting that transcription of rRNA genes takes place in the dense fibrillar component. Despite the fact that rRNA transcription occurs in the dense fibrillar component of Ehrlich tumour cell nucleoli, we show in the present paper that dense fibrillar component containing rapidly labelled RNA can be visualized not only around but also inside the fibrillar centres.
Fibrillarin: a new protein of the nucleolus identified by autoimmune sera
Authors: Ochs R. L. , Lischwe M. A. , Spohn W. H. , Busch H.
Published: February 2012

Autoimmune serum from a patient with scleroderma was shown by indirect immunofluorescence to label nucleoli in a variety of cells tested including: rat kangaroo PtK2, Xenopus A6, 3T3, HeLa, and human peripheral blood lymphocytes. Immunoblot analysis of nucleolar proteins with the scleroderma antibody resulted in the labeling of a single protein band of 34 kD molecular weight with a pI of 8.5. Electron microscopic immunocytochemistry demonstrated that the protein recognized by the scleroderma antiserum was localized exclusively in the fibrillar region of the nucleolus which included both dense fibrillar and fibrillar center regions. Therefore, we have named this protein “fibrillarin”. Fibrillarin was found on putative chromosomal nucleolar organizer regions (NORs) in metaphase and anaphase, and during telophase fibrillarin was found to be an early marker for the site of formation of the newly forming nucleolus. Double label indirect immunofluorescence and immunoelectron microscopy on normal, actinomycin D‐segregated, and DRB‐treated nucleoli showed that fibrillarin and nucleolar protein B23 were predominantly localized to the fibrillar and granular regions of the nucleolus, respectively. RNase A and DNase I digestion of cells in situ demonstrated that fibrillarin was partially removed by RNase and completely removed by DNase. These results suggest that fibrillarin is a widely occurring basic nonhistone nucleolar protein whose location and nuclease sensitivity may indicate some structural and/or functional role in the rDNA‐containing dense fibrillar and fibrillar center regions of the nucleolus.
Electron microscopic studies of condensed mitotic chromosomes in the fission yeast Schizosaccharomyces pombe
Authors: Erard M. , Barker D. G.
Published: February 2012

By blocking cells in mitosis with the anti‐fungal drug thiabendazole, it has been possible to carry out ultrastructural studies on the condensed chromosomes of the fission yeast, Schizosaccharomyces pombe. It is estimated that the DNA in these chromosomes is compacted approximately 1000‐fold, and that the nucleoprotein density is similar to that of higher eukaryotic metaphase chromosomes. A basic structural component of the condensed chromosomes appears to be a 50‐60 nm fibre, which is often visible in a loop configuration on the periphery of the chromatids. This is reminiscent of the 50‐60 nm fibre loops which are frequently seen in preparations of metaphase chromosomes, and suggests that mechanisms of nucleoprotein folding may be similar in both lower and higher eukaryotes.
Ultrastructural localization of bronchial inhibitor in human airways using protein A‐gold technique
Authors: Puchelle E. , Hinnrasky J. , Tournier J. M. , Adnet J. J.
Published: February 2012

Gold immunolabelling of human airways using a polyclonal antibody specific for the bronchial inhibitor (brI) demonstrates that this protease inhibitor is present in the serous cells of the bronchial glands. Most of the largest secretory granules (89%) are uniformly stained for brI whereas the smallest granules (diameter less than 80 nm) appear frequently (68%) devoid of brI.
Simultaneous demonstration of 3 synaptic markers: nerve endings, localization of AChE and AChR clusters at neuromuscular junctions of the rat in vitro
Authors: de la Porte S. , Courbin P. , Chapron J. , Hantaz‐Ambroise D. , Koenig J.
Published: February 2012

Our triple labelling method allows the AChE and AChR distributions and the nerve endings to be stained in the same preparation. This method which provides a detailed visualization of the synaptic contacts and is capable of revealing a weak AChE activity is particularly valuable in studies of synaptogenesis.
Granular and extra‐granular forms of immunoreactive calcitonin in normal rat C" cells
Authors: Treilhou‐Lahille F. , Pidoux E. , Day F. , Milhaud G. , Moukhtar M. S.
Published: February 2012

The intracellular localization of the intermediate calcitonin‐related peptides produced during calcitonin maturation (CT, 3.4 Kd) from the polyprotein precursor (15 Kd) has been studied by means of subcellular fractionation of normal adult rat thyroid using a continuous hypertonic Percoll gradient. A fraction B (Bottom), containing the secretory granules, was separated from a fraction T (Top) constituted of rough and smooth membranes devoid of granules. Immunoreactive calcitonin extracted from both fractions was heterogeneous when analysed by gel electrophoresis followed by radioimmunoassay. In fraction T, the immunoreactive molecules assayed were associated with the membranes. Their apparent molecular weights (lower than 18 Kd) were compatible with the intermediates predicted by the aminoacid sequence of the precursor. However the maturation was not complete, as indicated by the absence of the monomer. The smallest molecular weight detected (4‐4.5 Kd) was compatible with a calcitonin‐katacalcin uncleaved molecule. These data strongly suggest the occurrence of a cleavage separating the N‐terminal part of the molecule during the pre‐granular step of calcitonin secretory pathway. In the granular fraction, the monomer constituted the granular matrix, representing 65% of the total immunoreactivity. The remainder was associated with the granules membranes, consisting of the 4‐4.5 Kd precursor and some 43 Kd material which has already been demonstrated by others to be covalent polymers of calcitonin [17]. It is thus concluded that a second cleavage could take place in the granules where the major immunoreactive form is the processed calcitonin, either as free monomer or as covalent polymers associated with the membrane of the granules.
Internalization and recycling of lutropin receptors upon stimulation by porcine lutropin and human choriogonadotropin in porcine Leydig cells
Authors: Genty N. , Salesse R. , Garnier J.
Published: February 2012

Porcine lutropin (pLH) and human choriogonadotropin (hCG) recognize the same hormonal receptor and elicit the same steroidogenic response in porcine Leydig cells in primary culture. We compared the variation in the number of occupied and free receptors present on the cell surface under short‐term stimulation by the two hormones at 35 degrees C. Both hormones produced a rapid dose‐dependent decrease in the total number of the gonadotropin receptors present on the cell surface with a half‐life of 8‐10 min. This decrease was reversible upon hormone removal and receptors were recovered on the cell surface with the same half‐life of 8‐10 min. With pLH, the receptors were recycled in a free state, but in the presence of hCG the receptors were recycled in an occupied state. This difference could be related to the higher affinity of hCG for the receptor in 150 mM NaCl buffer (Ka = 1.6 × 10(9) for hCG and 1.5 × 10(7) for pLH) and higher stability to acid pH of the hCG‐receptor complex (dissociation pK = 3.7 for hCG and 4.5 for pLH).
Chemical inducers of differentiation, dimethylsulfoxide, butyric acid, and dimethylthiourea, induce selective ultrastructural patterns in B16 melanoma cells
Authors: Malik H. , Nordenberg J. , Novogrodsky A. , Fuchs A. , Malik Z.
Published: February 2012

The morphology and ultrastructure of B16 melanoma cells was examined after treatment of the cells with the chemical inducers of differentiation dimethylsulfoxide (DMSO), butyric acid, and dimethylthiourea (DMTU). The treated B16 melanoma cells seemed to be enlarged and more flattened, and to possess dendrite‐like structures as revealed by scanning electron microscopy. The main ultrastructural features, depicted by transmission electron microscopy in DMSO‐treated B16 cells were: a marked increase in melanin granules, migration of the melanin granules to the dendrites, and appearance of melanosome aggregates. Butyric acid did not induce melanin biosynthesis; however, it stimulated rough endoplasmic reticulum (RER) formation all over the cytoplasm. The DMTU‐treated cells also showed a well developed RER accompanied by early stages of melanosomes and melanin granules. The increase in the endoplasmic reticulum was also reflected by enhancement of NADPH cytochrome c reductase activity, an enzymatic marker of the endoplasmic reticulum. The mitochondria in the DMTU‐treated cells were swollen with disrupted cristae. The results indicate that DMSO, butyric acid, and DMTU induce different ultrastructural patterns in B16 melanoma cells. These findings correlate with the biochemical alterations induced in melanoma cells by these agents.
Distribution of nuclear matrix proteins in interphase CHO cells and rearrangements during the cell cycle. An ultrastructural study
Authors: Noaillac‐Depeyre J. , Azum M. C. , Geraud M. L. , Mathieu C. , Gas N.
Published: February 2012

The nuclear matrix contains a group of residual non‐histone proteins which remain structurally organized after extensive extraction of isolated nuclei with a high salt buffer, nucleases and a non‐ionic detergent. Electron microscopic examination shows that the nuclear matrix is composed of a pore‐complex lamina, an intranuclear network and residual nucleoli. In CHO cells biochemical analyses performed by one‐dimensional SDS‐PAGE show three major nuclear matrix polypeptides with molecular weights between 60 and 70 kDa. Polyclonal antibodies produced against these polypeptides were used to determine their nuclear distribution. Using immunoblotting, these proteins were found in whole nuclei, nuclear matrix, and in the intranuclear network but not in the pore‐complex lamina. In order to determine the relationship between these structural proteins and the organization of the nucleus, the proteins were localized in situ. Ultrastructural detection was carried out by immunogold staining of thin sections of Lowicryl K4M‐embedded cells. In interphase nuclei all condensed chromatin clumps were labelled. The nucleolus and the interchromatin granules were never immunogold‐stained. During mitosis, the label was found to be associated with the chromosomes. This study shows that unlike the lamins, these 60‐70 kDa nuclear matrix proteins are associated with the condensed chromatin throughout the cell cycle.
Fine structure of Blastocrithidia culicis as seen in thin sections and freeze‐fracture replicas
Authors: Soares M. J. , de Souza W.
Published: February 2012

The fine structure of epimastigotes of Blastocrithidia culicis was studied by transmission electron microscopy of thin sections and freeze‐fracture replicas. This parasite presents a well developed endoplasmic reticulum and Golgi complex systems. Differences in the density and organization of the intramembranous particles were observed between the membranes which enclose the cell body and the flagellum. Ridge‐like elevations, visualized in freeze‐fracture replicas, were observed in sites where the mitochondrial branches touched the plasma membrane. A special array of membrane particles was observed on both faces of the flagellar and the cell body membranes at the region where the flagellum adheres to the cell body. It appeared as strands made of two rows of membrane particles. Filipin‐treated cells were used for the localization of membrane sterols in freeze‐fracture replicas. The number of filipin‐sterol complexes varied from cell to cell. In some cells, rows of filipin‐sterol complexes were seen. No complexes were observed in the region of the attachment of the flagellum to the cell body.
Precise localization of an overproduced periplasmic protein in Escherichia coli: use of double immuno‐gold labelling
Authors: Bernadac A. , Bolla J. M. , Lazdunski C. , Inouye M. , Pages J. M.
Published: February 2012

The subcellular localization of beta‐lactamase produced by a secretion‐cloning vector pIN‐III was studied by immunolabelling of frozen thin sections of Escherichia coli. Using double immuno‐gold detections and internal reference proteins, it is shown here that beta‐lactamase encoded by this vector can be exported and that its overproduction leads to aggregation within the periplasm. This aggregation induces the appearance of electron‐dense areas immunolabelled by the antiserum directed against the beta‐lactamase at the external side of the cytoplasmic membrane. The overproduced enzyme is also secreted to the medium in vesicles budding from the outer membrane of lpp strains.
Membrane fluidity of Toxoplasma gondii: a fluorescence polarization study
Authors: Gallois Yves , Foussard Françoise , Girault Andrée , Hodbert Jocelyne , Tricaud Anne , Mauras Geneviève , Motta Claude
Published: February 2012

Toxoplasma gondii membrane fluidity was investigated by fluorescence polarization. We used 1,6‐diphenyl 1,3,5‐hexatriene (DPH) as a fluorescent hydrophobic probe. Fluorescence anisotropy (r) and degree of order (s) showed high fluidity properties. Chemical analysis was performed on this parasite. We found a low cholesterol/phospholipid ratio, many unsaturated fatty acid chains, and high phosphatidylcholine and low sphingomyelin amounts. These results were in good agreement with the observed high fluidity. This may be related to the great adaptability of Toxoplasma gondii in infesting a wide variety of host cells.
Three‐dimensional computer reconstructions from serial sections of cell nuclei
Authors: Geraud Gérard , Soyer Alain , Epelboin Yves
Published: February 2012

The analysis of ultrathin serial sections as 3‐dimensional (3D) information requires interpretation and display of a large amount of data. We suggest a simple way to solve this problem; it permits presentation of a series of sections as a 3D color image of good quality. It involves a picture system with specialized hardware and software written for this purpose.

3D images of cellular organelles have been drawn either by manually defining the contour of the objects or by thresholding of the volumes in the structures.

These 2 methods allow rapid drawing of the image on the screen. It is possible to determine the position, shape and size of 3D structures. This interactive system allows the user to choose between several option: colors, removal of parts of the object, and cutout.
Ciliogenesis and centriole formation in the mouse embryonic nervous system. An ultrastructural analysis
Authors: Cohen Edith , Binet Stéphane , Meininger Vincent
Published: February 2012

Serial ultrathin sections were used to study the formation of the primary cilium and the centriolar apparatus, basal body, and centriole in the neuroepithelial primordial cell of the embryonic nervous system in the mouse. At the end of mitosis, the centrioles seem to migrate toward the ventricular process of the neuroepithelial cell, near the ventricular surface. One of these centrioles, the nearest to the ventricular surface, begins to mature to form a basal body, since its tip is capped by a vesicle probably originating in the cytoplasm. This vesicle fuses with the plasmalemma and the cilium growth by the centrifugal extension of the 9 sets of microtubule doublets. These 9 sets invade the thick base of the cilium which is initially capped by a ball‐shaped tip with the appearance of a mushroom cilium. The secondary extension of 7, then 5, and finally 2 sets of microtubule doublets contribute to form the tip of the mature cilium, which is associated with a mature centriolar apparatus formed by a basal body and a centriole. Centriologenesis occurs before mitosis and is concomitant with the progressive resorption of the cilium. The daughter centriole, or procentriole, begins to take form near the tips of fibrils that extend perpendicularly and at a short distance from the wall of the parent centriole. Osmiophilic material accumulates around these fibrils, and gives rise to the microtubules of the mature daughter centriole. These centrioles formed by a centriolar process are further engaged in mitosis, after the total resorption of the cilium. This pattern of development suggests that in the primordial cells of the embryonic nervous system, centriologenesis and ciliogenesis are 2 independent phenomena.
Ciliary beat and cell motility of Dunaliella: computer analysis of high speed microcinematography
Authors: Schoevaert Damien , Krishnaswamy Sushila , Couturier Martine , Marano Francine
Published: February 2012

A high‐speed microcinematographic study was performed on the biflagellate unicellular alga Dunaliella. A frame‐by‐frame analysis has shown that the two flagella never beat at the same frequency. For a better characterization of the bending pattern of the two flagella, a new automated method of image analysis has been developed. The method allowed an automatic acquisition of a line characterizing the Dunaliella flagellum and its mathematical modelling. From this model, some binding parameters could be automatically measured, which have permitted determination of the velocities of formation and propagation of flagellar waves and the variation of the curvature radius of the bends between the two flagella. Both flagella showed a similar pattern of ciliary beat. The most important difference was the lengthening of the initiation phase for the slower flagella.
Incorporation of argyrophilic proteins into the nucleolus‐associated chromatin caused by exposure to actinomycin D
Authors: Sato Seiichi
Published: February 2012

The nucleolus‐associated chromatin (NAC) became argyrophilic when the root tips of Vicia faba were treated with 0.2 μg/ml actinomycin D (AMD) for 15 hr at 22°C. To determine how the argyrophilic NAC is formed, detailed observations were carried out on thin sections following silver staining and ribonucleoprotein (RNP) preferential staining. In a few instances, thick channels with loosely packed fibrillar material (light fibrillar area) were seen meandering throughout the nucleoli. Large granules 280–330 Å in diameter (300 Å granules), which responded positively to both RNP preferential staining and silver staining, were sometimes present within the light fibrillar area. Some fragments of NAC were also seen in the light fibrillar area and, interestingly, they responded positively to silver even though they were bleached by the RNP preferential staining. Most nucleoli showed a segregation of two major components, the fibrillar and granular components. The nucleolar vacuoles were localized strictly within the fibrillar component and usually accompanied the light fibrillar area or, alternatively, contained a number of 300 Å granules. Another category was characterized by the presence of poorly developed vacuoles in which the 300 Å granules were still found, and the spherical argyrophilic NAC associated with the surface of the nucleolus. The present observations suggest that AMD induces the DNA‐containing structure engaged in ribosomal RNA transcription to condense, and during this process some argyrophilic proteins are incorporated into the chromosomal structure thereby causing the NAC to become argyrophilic. In this context, the NAC is assumed to contain ribosomal RNA genes.
A 70 kDa microtubule‐associated protein in NIL8 cells comigrates with the 70 kDa heat shock protein
Authors: Weller Nancy K.
Published: February 2012

When eukaryotic cells are exposed to environmental stress such as elevated temperature, the synthesis of heat shock proteins (HSP) is stimulated. We have raised a monoclonal antibody to a 70 kDa cytoskeleton‐associated protein; this antibody also appears to recognize HSPs 68, 70 and 90, as well as an additional 40 kDa non‐heat shock protein. We have used this monoclonal antibody to study the localization of the 70 kDa protein in the cytoskeletons of NIL8 hamster fibroblasts. By selective sequential solubilization of the components of NIL8 cells and analysis of the resulting cytoskeletal preparations by Western blot technique and indirect immunofluorescence, we have shown that the 70 kDa protein is associated with microtubules in mitotic and interphase cells and comigrates with HSP70 on 2‐dimensional gel electrophoretigrams.
In vitro stability of pancreatic zymogen granules: roles of pH and calcium
Authors: Lebel Denis , Grondin Gilles , Paquette Jean
Published: February 2012

Purified preparations of pancreatic zymogen granules have the peculiar property of lysing instantaneously at neutral pH, a property clearly irreconcilable with the cytoplasmic pH of the acinar cell. Two important factors known for regulating the stability of secretory granules are calcium and pH. Fluorescence microscopy of acinar cells in the presence of weak bases showed that zymogen granules have an acidic pH. In vivo, abolition of the ΔpH by NH4Cl did not induce any lysis of the granules. In vitro, with purified granules, an acidic intragranular pH was measured. This ΔpH was produced by a Donnan potential. The importance for granule stability of keeping the intragranular pH acidic has been confirmed in vitro by addition of K+ and nigericin to the suspension medium. These conditions produced alkalinization of the granule matrix and caused instantaneous solubilization of the granules.

Concentrations of 15 mM total, and 10 mM free calcium were measured in purified granules. The importance of intragranular Ca2+ was evaluated by means of the ionophore A23187 which induced calcium efflux and granule lysis. The lysis induced by the calcium ionophore was in direct relation with the calcium efflux, since addition of Ca2+ to the medium, at concentrations corresponding to that measured in the granule, relieved the effect. The role of calcium‐binding sites on the cytoplasmic surface of the granules was investigated with Ca2+, EGTA, and La3+. Calcium did not have any damaging effects; EGTA induced a slight lysis, while lanthanum yielded a strong and spontaneous lysis at micromolar concentrations. In addition to calcium‐binding sites, La3+ would bind to specific sites on the granule that would be directly coupled to maintenance of its stability.

These findings suggest that the intragranular acidic pH and calcium are both important for the in vitro stability of the zymogen granule and that purified granules have lost, in the course of purification, some cytoplasmic factors that in vivo, control the permeability of the membrane to protons, and chloride more particularly. Calcium‐binding sites and other specific sites probed with La3+, presumably on proteins at the surface of the granule, are also believed to have key roles in preserving the integrity of the membrane and the resulting stability of the granule.
Binucleate cells in the Ehrlich ascites tumor. Autoradiographic labeling
Authors: Pertusa Jose , Pellicer Jose A. , Alcober Vicente
Published: February 2012

An autoradiographic study was performed on binucleate and mitotic cells in the Ehrlich ascites tumor (EAT) untreated and after treatment with 5‐fluorouracil (FU).

The number of binucleate cells was greater in the treated tumor than in the controls. It was also observed that the number of labeled mitoses was greater in the Fu‐treated tumor.

Autoradiographic labeling showed that the cells that proved to be binucleate had previously passed through S‐phase; thus, these cells belonged to the proliferative compartment.
Tridimensional analysis of the formation of secretory vesicles in the Golgi apparatus of absorptive columnar cells of the mouse colon
Authors: Rambourg Alain , Clermont Yves , Chrétien Monique
Published: February 2012

The tridimensional structure of the Golgi apparatus has been studied in the absorptive cells of the mouse colon by means of reduced osmium postfixation and phosphatase cytochemistry. In thick sections of tissue impregnated with osmium tetroxide or treated with a technique to demonstrate TPPase activity, the Golgi formed a continuous ribbon‐like structure capping the upper pole of the nucleus. Along the longitudinal axis of this ribbon, compact zones made up of super‐posed flattened saccules alternated with less compact zones which consisted of highly perforated saccules of bridging anastomosed tubules. In the cis‐trans axis, the following elements were observed: (1) a cis element consisting of a continuous osmiophilic tubular network; (2) two or three subjacent elements selectively perforated by wells; (3) a trans compartment made up of two or three TPPase‐reactive sacculotubular elements, some showing a “peeling‐off” configuration. In some regions, the first flattened saccule of this trans compartment displayed discrete ovoid dilatations, located in compact zones and containing a dense granulofibrillar material; in the subjacent elements this material was seen concentrated in nodular swellings, at the intersection of the meshes of anastomosed membranous tubules. 100–300 nm vesicles containing a similar dense granulofilamentous material were observed in the trans Golgi zone and interspersed in the supranuclear cytoplasm between the Golgi zone and the apical surface of the cell. Smaller vesicles 80–100 nm in diameter containing a fine dusty material were also seen in proximity. These morphological observations suggested that at least two kinds of material were segregated in the saccules of the trans compartment and packaged in vesicles of two class sizes that detached from the Golgi stack on its trans aspect.
Cell cycle‐specific variation of intercellular plasminogen activator activity in cultured human alveolar epithelial carcinoma and rat hepatoma cells
Authors: Orfanoudakis Georges , Zaoui Driss , Befort Jean‐Jacques , Bieth Joseph G.
Published: February 2012

Plasminogen activator activity was demonstrated in two carcinoma cell lines: A549 cells derived from a human alveolar epithelial carcinoma; and ZHC cells derived from a rat hepotoma. Beoth cells had intracellular plasminogen activator activity throughout their cell cycles and in each case this activity reached a maxumum. For A549 cells the maximal activity took place either during the G2 phase or in the course of the S to G2 transition, suggesting that plasminogen activator might play a role in cell division. For ZHC cells, the maximal activity occurred at the start of the S phase, suggesting that in these cells plasminogen activator might be involved in DNA replication.
Dynamics of pancreatic tissue cells in the rat exposed to long‐term caerulein treatment: 1. Biochemical, morphological and morphometrical evaluations
Authors: Morisset Jean , Grondin Gilles
Published: February 2012

This study was undertaken to evaluate whether hypertrophy and hyperplasia of the pancreatic acinar cells induced by caerulein remained after termination of the hormonal treatment. Rats received subcutaneous injections of saline or caerulein for 4 days and were killed immediately after termination of treatment or 2, 15 and 50 days later. Caerulein treatment induced significant increases in pancreatic weight and contents of DNA, RNA, protein, amylase and chymotrypsinogen along with an increased number of acinar cells per acinus and zymogen granules per acinar cells. During the post‐treatment period, the caerulein‐treated pancreas reverted to control values for their contents in proteins, enzymes and RNA and number of zymogen granules per acinar cell while the number of pancreatic cells remained constant as indicated by the absence of modification in total DNA content and acinar cells per acinus. During that same period, saline‐treated pancreas exhibited constant growth. These morphological and biochemical data indicate that the already present and newly formed acinar cells can remain in place once the trophic stimulus is withdrawn and that they can adjust their cellular components and thus their digestive capacity to the circulating levels of endogeneous cholecystokinin released in response to normal meals.
Effect of dimethyl sulfoxide on mouse embryo fibroblasts: inhibition of plasminogen activator inhibitor deposition and interference with early events of serum‐stimulated growth
Authors: Nagashunmugam Thandavarayan , Srinivas Shankara , Shanmugam Govindaswamy
Published: February 2012

Quiescent and serum‐stimulated cultures of Swiss mouse embryo fibroblasts (MEF) showed alterations in cell morphology including an enlargement in size upon treatment with 2% dimethyl sulfoxide (DMSO). Treatment of MEF and monkey kidney epithelial cells (MK2) with 2% DMSO at the early periods of serum‐stimulated growth inhibited RNA, protein and DNA synthesis. DMSO treatment of cells at late stages of serum‐stimulated growth (MEF after 1 hr and MK2 cells after 3 hr of stimulation) had little effect on DNA and protein synthesis although cell enlargement occurred in these cells. When the [35S]methionine labelled proteins of the control and the DMSO treated cells were analysed by high resolution polyacrylamide gel electrophoresis, no apparent difference was observed in the pattern of intracellular proteins of these cells. In contrast, the extracellular levels of two serum‐induced secreted proteins of MEF (Mr 48 000 and 26 000) were dramatically reduced by DMSO treatment. The DMSO sensitive 48 kDa protein was found to be the major component of the extracellular matrix, while the 26 kDa protein was not. The 48 kDa protein was identified as plasminogen activator inhibitor (PAI‐1). Densitometric quantitation showed a gradual accumulation of this protein in the matrix of serum‐stimulated cells. The deposition of this protein in the matrix was inhibited by DMSO. Flow‐cytometric quantitation of indirect immunofluorescence indicated higher intracellular levels of the 48 kDa protein in fetal calf serum (FCS)+DMSO treated cells, suggesting that the low level of this protein in the medium of DMSO treated cells is probably due to lack of transport of this protein from the cells into the medium.
Immunocytochemical localization of Δ3, Δ2‐enoyl‐CoA isomerase in rat liver. The effects of di‐(2‐ethylhexyl)phthalate, a peroxisome proliferator
Authors: Yokota Sadaki , Hirose Akihiko , Mizugaki Michinao
Published: February 2012

Immunocytochemical localization of Δ3, Δ2‐enoyl‐CoA isomerase (isomerase) was investigated in rat liver. Livers of di‐(2‐ethylhexyl)phthalate) (DEHP)‐treated or untreated rats were perfusion‐fixed and embedded in Epon or Lowicryl K4M. By light microscopy, reaction deposits for the enzyme were present in the cytoplasmic granules of hepatocytes and interlobular bile duct epithelium. Weak staining was noted in sinus‐lining cells. After administration of DEHP, the granular staining of the hepatocytes was markedly enhanced, whereas the staining reaction of the sinus‐lining cells decreased. The isomerase staining pattern was quite similar to that of long‐chain acyl‐CoA dehydrogenase (a mitochondrial marker), but different from that of catalase (a peroxisomal marker). Under electron microscopy, gold particles for isomerase were seen to be confined mainly to mitochondria of the hepatocytes, the bile duct epithelial cells and sinus‐lining cells. Peroxisomes were weakly labeled. After DEHP administration, the peroxisomes were markedly induced, but the mitochondria were not. Quantitative analysis showed that the induction of the peroxisomal isomerase was only 2‐fold whereas the mitochondrial isomerase was enhanced about 5‐fold, 40 times as high as the peroxisomal enzyme. The results show that the mitochondria are the main intracellular site for isomerase and the peroxisomes a minor site. The mitochondrial isomerase of the rat liver is markedly induced by peroxisome proliferators, DEHP and clofibrate.
Farnesylacetone, a sesquiterpenic hormone of crustacea, inhibits electron transport in isolated rat liver mitochondria
Authors: Dupont Jacques , Rodes Jean‐François , Berreur‐Bonnenfant Josette , Carre Marie‐Claude , Tekitek Ali , Berreur Paul
Published: February 2012

Farnesylacetone (C18 H30 0) is a male hormone extracted from the androgenic gland of crab, Carcinus maenas. Appropriate enzymatic assays, as well as spectrophotometric studies, indicate that micromolar concentrations of farnesylacetone interact with the electron transport pathway of rat liver mitochondria. By the use of artificial electron donors and electron acceptors, it is shown that farnesylacetone immediately inhibits the electron transfer within complex I (NADH ubiquinone reductase activity) and complex II (succinate ubiquinone reductase activity). It is proposed that farnesylacetone could interact with these two complexes of the respiratory chain at the level of the iron‐sulfur centers implicated in the dehydrogenase activities. These observations are compared with the results obtained with terpenic molecules which interact with mitochondrial respiration.
Translation in a cell‐free system, and in Xenopus oocytes, of mRNA which specify a cadmium‐binding protein in Nereis diversicolor (annelida, polychaeta)
Authors: Benouareth Djamal Eddine , Dhainaut‐Courtois Nicole , Porchet‐Hennere Eliane , Curgy Jean‐Jacques
Published: February 2012

The presence in the marine worm Nereis diversicolor of a low molecular mass protein with the capacity to bind cadmium has been previously demonstrated [5].

Poly(A)+‐mRNA were extracted from coelomocytes of Nereis diversicolor and were translated either in vitro, using a rabbit reticulocyte lysate, or in vivo into Xenopus laevis oocytes. Analysis of synthesized polypeptides by enzyme‐linked immunosorbent assay (ELISA) and by Western blotting, using a specific monoclonal anti‐MP II antibody, showed that this metalloprotein was translated both in in vitro and in vivo translation systems, with an apparent molecular mass of 11–13 kDa. Two other products, with 26.5 and 28 kDa molecular mass, cross‐reacted with the monoclonal anti‐MP II antibodies. The present work confirms that coelomocytes are sites of important synthesis of MP II‐mRNA.
Actin and spectrin‐like (Mr= 260–240 000) proteins in gregarines
Authors: Ghazali Machhour , Philippe Michel , Deguercy Alain , Gounon Pierre , Gallo Jean‐Marc , Schrevel Joseph
Published: February 2012

In Gregarina blaberae a Mr = 47 000 and a Mr = 260–240 000 doublet polypeptides reacted in immunoblotting: i) with a polyclonal monospecific rabbit antibody to frog muscular actin, a monoclonal anti‐actin antibody against chicken gizzard; and ii) with polyclonal and monoclonal antibodies to human erythrocyte β‐spectrin, respectively. The Mr = 47 000 actin‐like protein is associated with the ghost and a contractille cytoplasmic extract. The presence of an actin‐like protein in Gregarina and Lecudina and its cellular distribution in the cortex indicated that the gliding movement might involve an actin‐myosin system in contrast to previous studies. Immunofluorescence showed clear differences between the anterior part of Gregarina and Lecudina which illustrated the high cell polarity of these protozoa. The Mr = 260–240 000 doublet was detected in SDS‐PAGE from G. blaberae trophozoite ghosts but not in the cytoplasmic extracts or in extracts from sexual stages, indicating that the presence of these spectrin‐like proteins is stage‐dependent. Visualization of the Mr = 260–240 000 by immunofluorescence showed clear species differences, with rings arranged perpendicular to the longitudinal narrow folds of G. blaberae, with longitudinal lines underlying the folds of L. pellucida and with lines separating the large folds of Selenidium pendula. The cellular distribution is consistent with a stabilizer function of the spectrin‐like proteins in the scaffolding of the cortex of gregarines according to the high diversity of the cell‐shape and the cell motility systems in gregarines. The presence of spectrin‐like proteins in protozoa and particularly in parasites from primitive arthropods indicated that ancestral spectrin genes could the Mr = 260–240 000 form.
Specific characters of vessel primary walls during the early stages of wood differentiation
Authors: Catesson Anne‐Marie
Published: February 2012

At the peak of its activity, the cambial zone comprises several layers of undifferentiated, apparently identical cells. In order to find criteria indicating the commitment of cambial cells either to phloem or xylem, early changes in primary wall structure and composition were looked for, using sycamore branches as experimental material. Several chemicals were employed to extract cell wall polysaccharides. Treated specimens were studied by electron microscopy after selective staining. Extracted matrix components were analysed through HPLC. Comparison of ultrastructural and biochemical results indicated that in contrast to phloem derivatives cellulose biosynthesis in xylem derivatives was delayed. Among xylem‐committed cells, the very young vessels were characterized by a nearly complete lack of a cellulose skeleton and a high amount of xylose‐rich hemicelluloses in their primary walls. This organization would cause the wall plasticity necessary for the cell extensive growth in diameter.
Motility processes in Acantharia (protozoa) III. Calcium regulation of the contraction ‐ relaxation cycles of in vivo myonemes
Authors: Febvre Jean , Febvre‐Chevalier Collete
Published: February 2012

The myonemes in the marine pelagic protozoa Acantharia are contractile organelles involved in buoyancy regulation. It was previously shown that they can perform three kinds of movement: rapid contraction, slow undulation and slow relaxation. They consist of a periodically striated bundle of 2–4 nm nonactin filaments that are twisted in pairs and shortened by a coiling mechanism. After permeabilization or demembranation, contraction and relaxation can still be performed by varying Ca2+ concentration and ATP is not needed.

In the present paper, we have studied the role of Ca2+ and inhibitors of energy production in intact cells. Our data suggest that; (i) the in vivo rapid contraction subsequent to mechanical or electrical stimulation is triggered by Ca2+ influx across the cell membrane; (ii) the slow contraction that takes place during the undulating movement depends on Ca2+ release provided by internal calcium stores; (iii) the rapid contraction as well as the progressive shortening that occurs during the slow undulating movement are caused by Ca2+ binding to the myoneme filaments; (iv) ATP is not directly involved in the saturation by Ca2+ of Ca2+ sensitive sites located along the myoneme microstrands; (v) regulation of the movements of Ca2+ within the cytoplasm depends mainly upon the alternative pathway of ATP production; (vi) calmodulin is presumably involved in this regulation. A tentative cytophysiologic interpretation of the mechanism of contractility is proposed.
Characterization and serial propagation of mouse prostate epithelial cells in serum‐free medium
Authors: Chowdhury Anisuzzaman , Harber Gregory J. , Chopra Dharam P.
Published: February 2012

Epithelial cell cultures derived from the ventral prostate of normal adult mice have been propagated in serum‐free medium. The cultures were initiated and maintained in Ham's F‐12 nutrient mixture supplemented with insulin (5 μg/ml), EGF (10 ng/ml), hydrocortisone (0.5 μg/ml), cholera toxin (10 ng/ml), bovine pituitary extract (25 μg protein/ml) and antibiotics. The cells exhibited microvilli on cell surfaces, interdigitations and junctional complexes including desmosomes between cells, and cytokeratins in cytoplasm which are characteristic of epithelial cells. In addition, the cells exhibited the tissue‐specific markers, prostatic acid phosphatase and prostate‐specific antigen.
Diazepam induces abnormal mitosis in the early Drosophila embryo
Authors: Callaini Giuliano , Dallai Romano , Riparbell Maria Giovanna
Published: February 2012

Drosophila embryos, because of their high proportion of dividing nuclei, offer many advantages for the study of the mitotic cycle. In the present study we combined immunofluorescence with interference contrast techniques to follow centrosome and spindle behavior in embryos exposed to diazepam during the first stages of development. Exposure to 100 μg/ml of diazepam produced polyploid and aneuploid figures resulting from the unusual fusion of one or more adjacent spindles. Diazepam also causes the inhibition of centrosome shifting and induces the formation of monopolar spindles during the metaphase‐anaphase transition.
Transcription of dispersed repeated sequences during Pleurodeles waltl oogenesis
Authors: Randsholt Neel B. , Muller Jean‐Pierre , Loones Marie‐Thérèse
Published: February 2012

Summary— Several repeated DNA sequences were isolated from a partial genomic DNA library of the newt Pleurodeles waltl. These repeated DNA elements are dispersed over the 12 P. waltl bivalents, and some of them are transcribed in the oocyte. We describe the localization of label following in situ hybridization to nascent RNA attached to the lateral loops of lampbrush chromosomes. Variations in the number and the location of labelled loops were constantly found for several of the probes. The results are discussed in view of the “cotranscription model” of RNA synthesis on lampbrush chromosomes. We speculate on the possible origins of variation in transcription on lampbrush loops.