bluuebunny/crossref_metadata_2025 huggingface dataset:
Binding of bacteria in lymphocyte subpopulations: role of lectin‐carbohydrate interactions
Authors: Teodorescu M.
Published: February 2012

Bacteria have been found to bind to lymphocyte subpopulations in a highly reproducible manner. Some of these bacteria such as B. melitensis and a strain of E. coli binds to mammalian B. cells. The binding of B. melitensis and other bacteria is due, at least in part, to lectins on lymphocytes interacting with the carbohydrates on the LPS or LTA of the bacteria. These receptors for bacteria give some indications regarding the functional potential of the cells, suggesting the possibility that the receptors identified by bacteria are used in cellular interactions with normal or malignant cells.
Dynamics of zona pellucida formation by the mouse oocyte. An autoradiographic study
Authors: Fléchon J. E. , Pavlok A. , Kopecný V.
Published: February 2012

The dynamics of the synthesis of the mouse oocyte zona pellucida was studied using light microscope autoradiography after intrabursal injection of (3H) ‐fucose. Zona accretion occurred continuously from the inside, demonstrating that the oocyte itself elaborated all the raw material of the zona. The duration of zona synthesis corresponded to that of the oocyte growth phase. Zona secretion stopped one week before ovulation and there was no renewal of its material.
Regulation of intracisternal A particles in mouse teratocarcinoma cells: involvement of DNA methylation in transcriptional control
Authors: de Oca F. Hojman‐Montes , Lasneret J. , Dianoux L. , Canivet M. , Ravicovitch‐Ravier R. , Périès J.
Published: February 2012

The methylation state of Intracisternal A Particle (IAP) genes in mouse teratocarcinoma cell lines has been investigated as an approach to study the regulation of the expression of these particles. Treatment of the cells with the methylation inhibitor 5‐azacytidine induces the production of the particles in all the cells; the induction is particularly striking in an embryonal carcinoma cell line which is normally devoid of IAPs. The induction is accompanied by decrease in DNA methylation as demonstrated by using the methylation sensitive isoschizomer enzymes MspI and HpaII. Hypomethylation of the IAP genes correlates with accumulation of IAP, specific polyadenylated RNA reinforcing the hypothesis that methylation plays an important role in the control of IAP expression.
Cellular localization of class I (HLA‐A, B, C) and class II (HLA‐DR and DQ) MHC antigens on the epithelial cells of normal human jejunum
Authors: Gorvel J. P. , Sarles J. , Maroux S. , Olive D. , Mawas C.
Published: February 2012

HLA class I and class II (HLA‐DR (human I‐E equivalent) and DQ (human I‐A equivalent] antigens were localized by immunofluorescence technique on thin frozen sections of normal human jejunum using a panel of monomorphic monoclonal antibodies. HLA class I (A, B and C) and HLA‐DR molecules were found in the basolateral membrane of enterocytes; HLA‐DR were also detected in a patchy distribution in the apical part of enterocytes; HLA‐DQ molecules (the human equivalent of the murine I‐A molecular subset) were not detected on normal enterocytes. All three molecules were detected on the membrane of lymphocytes and monocytes present in the lamina propria.
Effects of antimicrotubular agents in cAMP production and in steroidogenic response of isolated rat Leydig cells
Authors: Saltarelli D. , De la Llosa‐Hermier M. P. , Tertrin‐Clary C. , Hermier C.
Published: February 2012

In dispersed rat Leydig cells, colchicine was found to stimulate basal cAMP production and testosterone secretion in a dose and time‐dependent manner, but to a lesser extent than LH. However, these drugs are unable to stimulate adenylate cyclase activity in plasma membranes isolated from these cells. The amount of testosterone secreted at 150 min under the influence of colchicine and LH added simultaneously was not different from the amount produced during stimulation by LH alone. It is only after exposure of the cells for 1 hr to colchicine that the accumulation of cAMP in response to LH was inhibited; furthermore, both intracellular and medium testosterone accumulation in response to the hormone were reduced. Similar effects were observed with two other alkaloids, vinblastine and podophyllotoxin. The three drugs also inhibited the stimulation of testosterone secretion by 8‐Br‐cAMP or choleratoxin. These studies suggest that the state of microtubule polymerization and/or tubulin can influence the process of steroidogenesis in rat Leydig cells.
Three‐dimensional reconstruction of innermost chorion layer from Drosophila melanogaster
Authors: Margaritis L. H. , Hamodrakas S. J. , Arad T. , Leonard K. R.
Published: February 2012

A low‐resolution three‐dimensional structure of the crystalline innermost chorion layer (ICL) has been calculated from electron microscope images of tilted negatively stained crystals. The isolated ICL is a single layer, about 12 nm thick and appears to be made up of two types of subunits, each approximately 3 nm in diameter, arranged regularly as groups of four heterodimers in space group C222. Linking density between these groups of subunits, maintaining the integrity of the layer, appears to be confined mainly to the outer surfaces of the ICL.
High molecular weight microtubule‐associated proteins from pig brain are immunologically related to human erythrocyte membrane proteins spectrin, ankyrin, proteins 4.1 and 4.2
Authors: Hill A. M. , Cassoly R. , Chetrite G. , Pantaloni D.
Published: February 2012

The microtubule‐associated proteins MAPs 1 and 2 from pig brain have been found to react with antibodies directed against human ankyrin and spectrin, respectively (Bennett and Davis, 1981; Davis and Bennett, 1982). In a complementary approach we have prepared antibodies against MAP1 alpha. MAP1 gamma and MAP2 purified from pig brain and tested their reactivity with human erythrocyte membrane proteins. Anti‐MAP1 alpha was shown to react with alpha and beta‐spectrin and with protein 4.1; anti‐MAP1 gamma reacted with alpha‐spectrin and ankyrin and with a 60 K peptide which copurified with human spectrin. Finally anti‐MAP2 was specific for beta‐spectrin and protein 4.2. The biological function of protein 4.2 is still unknown but details on the interactions between ankyrin, spectrin and protein 4.1 and their role in mediating the linkage of oligomeric actin on the erythrocyte membrane are well documented. The present results, which demonstrate extended immunological analogies between pig brain high molecular weight MAPs and human erythrocyte membrane proteins, may reflect the presence, in the two families of proteins, of similar functionally important epitopes.
Epstein‐Barr virus transformed lymphoid cell lines as a new model system in culture for the study of GM2‐gangliosidoses: Tay‐Sachs and Sandhoff diseases
Authors: Maret A. , Salvayre R. , Negre A. , Bes J. C. , Douste‐Blazy L.
Published: February 2012

Epstein‐Barr Virus transformed cell lines (LCL) were established from blood B‐lymphocytes of patients affected with GM2‐gangliosidoses variant O (Sandhoff disease, SD) and variant B (Tay‐Sachs disease, TSD). LCL from SD showed a severe deficiency of activity of the major lysosomal beta‐N‐acetylhexosaminidase isoenzymes, Hex A and B; the residual activity was due to Hex S and Hex C. In LCL from TSD, the whole Hex activity was not deficient but isoenzyme composition was completely abnormal. Ultrastructural investigations showed the presence of pleiomorphic enlarged lysosomes appearing as clear vacuoles containing a finely fibrillo‐granular material characteristic of the visceral lysosomal storage of gangliosidoses.
In vivo interaction between mouse liver lysosomes and chloroquine
Authors: Colombo M. I. , Bertini F.
Published: February 2012

Particles sedimenting at 27,000 g × 10 min (MLCQ) were separated from liver homogenates of mice injected with chloroquine (CQ). The MLCQ contained most of the drug recovered in the organ as well as 50% of the liver aryl sulphatase activity. The release of CQ from MLCQ was studied in some physicochemical conditions, and in the presence of various agents known to modify membrane composition and stability. At pH 7.4, the equilibrium between free and bound CQ depended on the dilution of the MLCQ, and the time to reach equilibrium was strongly influenced by the temperature of incubation. Several agents causing membrane disruption and lysosomal enzyme leakage, such as osmotic shock, sonication and digitonin, had little effect on the CQ release. Acid and alkaline buffers, 0.55 M KCl and 0.1% Triton X‐100 caused, instead, the immediate release of most of the bound CQ. Concentrations of digitonin causing the release of aryl sulphatase activity had little effect on bound CQ, suggesting that the drug is retained in lysosomes by forces and/or structures different in nature from those retaining most of the lysosomal enzyme activity. We think that the CQ trapped in lysosomes is bound to high affinity sites in membranous structures which are particularly altered by agents known to extract peripheral proteins from biological membranes or to change the conformation of molecular structures.
Rotation of the cell nucleus in living cells: a quantitative analysis
Authors: Bard F. , Bourgeois C. A. , Costagliola D. , Bouteille M.
Published: February 2012

Nuclear rotation is observed in a variety of cell types. However, few quantitative analyses are reported and the significance of this phenomenon is still unclear. To investigate this type of nuclear movement, we performed a quantitative analysis in mouse L‐929 fibroblasts, a cell line chosen since it displays a high nuclear rotational activity. Analyses were performed using time‐lapse microcinematography. The relationship between nuclear rotation and other cellular phenomena such as the cell cycle and locomotion were studied. Then, we investigated the rotation in a population of sister cells to study whether it is genetically determined. Finally, we performed a qualitative analysis of nuclear rotation in different cultured cell lines. Results show that nuclear rotations preferentially occur during the phases of the cell cycle which surround mitosis.
Carbonic anhydrase in the rat salivary glands: distribution and ultrastructural localization
Authors: Carpentier P. , Chetail M. , Fournie J.
Published: February 2012

Rat salivary glands were studied by Hanson's method to specify the ultrastructural localization of carbonic anhydrase (CA). Two different procedures were used: 1) The embedding of the tissues in water‐soluble resins, followed by the incubation of the resin sections on the medium. 2) The embedding in epon‐araldite of previously incubated frozen sections. Light and electron microscopy were used to observe the distribution and the ultrastructural localization of the cobalt precipitate. In parotid and mandibular glands, CA was localized in the secretion granules and the hyaloplasma of the secretory endpieces. The enzyme was also detected on the basal and lateral membranes of the striated duct cells in the three glands. In the convoluted granular duct cells of the mandibular gland CA was found in the hyaloplasma only. In the sublingual gland, CA was localized in the hyaloplasma of the serous crescents and no activity was detected in the mucous tubules. As regards the localization of the enzyme in the granules of the secretory endpieces of parotid and mandibular glands, it appears that CA has to be considered as a secretory product of these cells; this localization is consistent with the presence of the enzyme in rat saliva.
Morphological study on the entry of African swine fever virus into cells
Authors: Valdeira M. L. , Geraldes A.
Published: February 2012

The early interactions between African swine fever virus (ASFV) and monkey kidney cells in culture, and the effect of chloroquine were studied by electron microscopy. Our results indicate that ASFV uptake occurs by endocytosis: after attachment to the cell surface, the virions were seen in coated pits and were internalized by endocytosis in endosomes and finally in lysosomes. Virions in coated vesicles were never seen. All these steps were completed in about 15 min. Direct penetration of viruses through the plasma membrane was never observed. In order to elucidate the participation of an acidic intracellular compartment in the penetration of ASFV, we studied the effect of chloroquine, a lysosomotropic drug known to increase the pH of acidic intracellular vacuoles and to inhibit ASFV infection. In the presence of this drug there were no apparent alterations on binding, endocytosis and intracellular distribution of the viral particles. The main effect of chloroquine was to retain the virions in lysosomes. When the drug was removed from the medium, the viral particles disappeared and images of binding of viral membranes with the membranes of the intracellular vacuoles were obtained, suggesting that the inhibited step is the uncoating of the virus. Viral fusion with the plasma membrane was obtained when the medium was acidified to pH 5‐6. These results suggest that ASFV enters the cells by adsorptive endocytosis and that the uncoating process takes place intracellularly in a way similar to that described for Semliki Forest virus and other enveloped viruses.
A central role for cell osmolarity in isotonic fluid transport across epithelia
Authors: Fischbarg J. , Liebovitch L. S. , Koniarek J. P.
Published: February 2012

Previous theoretical models for solute‐solvent coupling in epithelia that dealt only with the intercellular channel did not predict isotonic transport except when very high cell membrane permeabilities were assumed. To study this issue, we have developed the formalisms for osmotic equilibration at an alternative location, the apical cell membrane (including its adjacent unstirred layer), which are somewhat simpler than those for the channel. Much as in other models, we confirm that only rather unrealistically high values of the cell membrane permeability lead to isotonic transport. We have also found, however, that isotonic transport can occur at much lower values of the cell membrane permeability if the concentration within the cell differs slightly from that in the ambient medium. This emphasizes the importance of incorporating the intracellular concentration as an integral part to any transport model, such as in the present apical membrane version of local osmosis.
Surface Plasmodium sugar‐binding components evidenced by fluorescent neoglycoproteins
Authors: Schrevel J. , Philippe M. , Bernard F. , Monsigny M.
Published: February 2012

A sugar‐binding component was shown to be present at the surface of endoerythrocytic Plasmodium berghei and P. chabaudi stages and merozoites by means of a panel of neoglycoproteins using fluorescence microscopy and flow cytofluorometry. The protein nature of this material was ascertained by the loss of sugar‐binding capacity upon trypsin treatment. This lectin‐like protein primarily bound neoglycoprotein‐borne N‐acetylglucosamine and secondarily bound neoglycoprotein‐borne alpha‐D‐glucose, beta‐D‐galactose and alpha‐L‐fucose. These results suggest the presence of at least one type of lectin‐like protein with an extended binding site accomodating several sugar units, and define its localization on the parasite surface.
Identification of two macrophage populations by flow cytometry monitoring of oxidative burst and phagocytic functions
Authors: Lepoivre M. , Roche A. C. , Tenu J. P. , Petit J. F. , Nolibe D. , Monsigny M.
Published: February 2012

Two populations of phagocytic cells from trehalose dimycolate‐elicited mouse peritoneal cells are demonstrated by flow cytofluorometry, using two fluorescent probes excited at the same wavelength (488 nm). Liposomes containing diethylenetriaminepentaacetate daunorubicin conjugate (maximum emission wavelength: 590 nm) allow the discrimination of phagocytes and non‐phagocytic cells. Among the phagocytes, an activated population is revealed by a cell‐associated fluorescence of the oxidation product of dichlorofluorescein diacetate (maximum emission wavelength: 520 nm).
Viral alkaline nuclease in intranuclear dense bodies induced by herpes simplex infection
Authors: Puvion‐Dutilleul F. , Pichard E.
Published: February 2012

The distribution of the herpes simplex virus alkaline nuclease (HSV DNase) in rabbit fibroblast cells infected with HSV type 1 or 2 (HSV‐1 or HSV‐2) has been examined with the aid of immunocytochemical techniques using gold particles as markers. HSV DNase was found to be accumulated within infected nuclei as early as 2.5 hr post‐infection. Labeled antibody to HSV DNase subsequently increased in all nuclei after 7 hr and 17 hr. At all times post‐infection the virus induced nuclear dense bodies were always the most intensely labeled structures. The association of HSV DNase with nucleoprotein containing structures was readily dissociated by hypotonic shock and detergent treatment, but its association with the dense bodies was not disrupted. Nucleolar 100 kDa protein was found to be simultaneously present in the dense bodies. This suggests that HSV DNase might interfere with ribosomal RNA synthesis and play a role in the degradation of the host‐cell metabolism.
Effects of castration on the epididymis of a non‐mammalian vertebrate: evolution of morphology, protein synthesis, and of specific mRNA levels
Authors: Morel F. , Courty Y. , Mesure M. , Dufaure J. P.
Published: February 2012

The lizard epididymis is an androgen‐dependent organ undergoing large variations in its structure and in protein synthesis ability during its annual cycle. It produces a major androgen‐dependent protein, the L protein. This work reports the effects of castration performed at 3 prominent points of the sexual cycle: stage 1 (epithelium reorganization) stage 3 (onset of secretory activity) stage 6 (full secretory activity). Evolution of various parameters (organ weight, histology, amount of soluble proteins, rate of soluble protein synthesis and of specific protein synthesis: L protein, and mRNA levels) was considered over a period ranging from 7 days to 15, 30 and 60 days. Deprivation of the testis was followed by an organ involution which was more or less accentuated or more or less rapid according to the stage of the operation but some peculiarities need to be emphasized. At first, the evolution of the organ was not stopped but it proceeded: at stage 1, there was cell division and a correlated increase in total protein synthesis (without L protein synthesis), at stage 3 total protein synthesis and L protein mRNA levels increased (synthesis of L protein proceeded up to 30 to 60 days), at stage 6 the involution was accelerated. These effects concerning stage 1 and particularly stage 3 appeared as a kind of a paradoxical induction. Secondly, the epithelium underwent phases of destruction and regeneration which were obviously not controlled by the testis.
Cytocidal effects of human fibroblasts on HeLa cells in vitro
Authors: Delinassios J. G.
Published: February 2012

Cocultivation of human fibroblasts and HeLa cells in vitro leads to the development of specific patterns of growth. These patterns depend on the cell density and cell‐cell ratio in the initial mixed inoculum. Human fibroblasts can cause extensive nuclear fragmentation and cellular disintegration of HeLa cells in vitro after coculture for periods longer than 10 days, without subculturing, and with medium replacement every 2 days. This phenomenon is preceded by directional locomotion of the fibroblastic population parallel to the edges of and around HeLa colonies and by overgrowth of both cell types at the border sites. A dense border is thus developed around the HeLa colonies. In the absence of refeeding every 2 days, HeLa cells can overgrow, pass the dense border and form a new zone. Refeeding at this stage can again cause the formation of a second concentric dense border around the HeLa zone. This phenomenon may represent an in vitro metaphor of the invasive property of neoplastic cells. It also points out, however, the importance of feeding for the activation of fibroblasts against HeLa cells.
Immunological study of the tissue expression of D‐beta‐hydroxybutyrate dehydrogenase, a ketone body‐converting enzyme
Authors: Coquard C. , Adami P. , Cherkaoui‐Malki M. , Fellmann D. , Latruffe N.
Published: February 2012

In rats, as in most mammal, ketone bodies are mainly produced in liver while they are metabolized in extrahepatic tissues. The expression of mitochondrial membrane‐bound D‐beta‐hydroxybutyrate dehydrogenase (BDH), a ketone body‐converting enzyme, has been estimated by two immunological techniques: immunohistofluorescence and Western blotting. The in situ labeling with anti‐BDH antibody shows that the enzyme is expressed differently among the organs. Furthermore, within a given organ there are strong differences according to the cell type. The quantification of the enzyme by immunoblotting reveals that liver mitochondria have the highest content (more than 3% in protein mass). This content is 3,5 and 10 times lower in kidney, heart and brain mitochondria, respectively. Parallel D‐beta‐hydroxybutyrate dehydrogenase activity measurements on isolated mitochondria show differences in molecular activity of this enzyme according to the tissue origin. Due to the phospholipid requirement of this enzyme these differences in molecular activity are related to specific membrane lipid composition.
Dermal tracts in frog skin: fibronectin pathways for cell migration
Authors: Denèfle J. P. , Zhu Q. L. , Lechaire J. P.
Published: February 2012

The dermis of the frog skin (Rana esculenta) displayed a remarkable organization of vertical and horizontal tracts. Vertical thick tracts connected the dermal Stratum spongiosum with the subcutaneous tissue. Horizontal thin tracts were found alongside and contiguous to them. The thick tracts were sheathed by collagen fibrils of the Stratum compactum which were vertically oriented (i.e. parallel to the axes of the tracts) according to the horizontal and orthogonal arrangement of the collagen bundles of the Stratum compactum. The thin tracts devoid of collagenous sheath were formed by clear spaces between superimposed collagen bundles of the dermal Stratum compactum. On vertical sections, the thick tracts were seen to contain fibronectin (FN), detected by indirect immunoperoxidase. Continuous vertical FN lines were centred in these tracts. On horizontal sections, a clear zone around these FN‐centred lines was also sheathed by FN. The thick tracts contained flattened pigmentary cells and fibroblasts; these cells were FN‐outlined. The thin tracts contained patches of FN and FN‐outlined fibroblasts. In culture, in vertical thick tracts, both pigmentary cells and fibroblasts disappeared when antiserum to FN was added to the culture medium. This suggested that thick tracts were pathways allowing pigmentary cells to move upward or downward between their usual upper dermal and lower subcutaneous localizations. Fewer fibroblasts were found in the thin tracts in the presence of antiserum to FN.
Evidence for two mechanisms of human erythrocyte endocytosis by Entamoeba histolytica‐like amoebae (Laredo strain)
Authors: Lejeune A. , Gicquaud C.
Published: February 2012

A study of the ultrastructural aspects of endocytosis of human erythrocytes by Entamoeba histolytica‐like amoebae (Laredo) revealed two different mechanisms of endocytosis. First, there is classical phagocytosis which consists of the formation of a phagocytotic pseudopod. This process begins with the engulfment of the red blood cell followed by its entrapment in a food vacuole of the same size as the erythrocyte. It is then digested in the food vacuole. The second means of endocytosis is achieved through a preliminary lytic attack on the red blood cell. Following attachment of the prey to the attacking cell, dendritic extensions elongate from the surface of the amoeba at the site of attachment. Intense folding and liquefaction of the red blood cell membrane is then observed. The fluid membrane is then sucked into the amoeba through a pinocytotic‐like channel. The end result is the formation of small vacuoles in the amoeba's cytoplasm, filled with the digested red blood cell.
Relationship between nucleoli and sex chromosomes during meiosis of the male wood lemming Myopus schisticolor: a fine‐structure study
Authors: Wolf K. W. , Winking H. , Fredga K.
Published: February 2012

Electron microscopy of ultrathin serial sections has been used to study the origin and fate of a mass of fibrillar material (FM) during spermatogenesis in the wood lemming Myopus schisticolor. In the course of early pachytene, one of the two nucleoli completely disappears. The remaining nucleolus loses its granular portion and acquires a “round body” encased by the fibrillar moiety, and the restructuring is accompanied by the appearance of FM in the close vicinity of this nucleolus. During diakinesis, the FM increases in volume and density and selectively infiltrates the chromatin of the XY pair. The intermingling of sex chromosomes and FM is at its maximum in metaphase I, giving the XY chromatin a patchy appearance. The FM separates along with the chromatin during the ensuing anaphase I and is shed from the chromosomes during early telophase I. By the time the nuclear envelope is reconstituted, the FM is completely separated from the chromatin. It disintegrates in the spermatids. The FM could not be stained using the Ag‐NOR technique. In the wood lemming, X and Y chromosomes show an end‐to‐end association without a detectable synaptonemal complex. The FM may contribute to the attachment of the two sex chromosomes to each other. Thus, the FM is considered to be a substitute for a chiasma, which normally guarantees proper segregation in anaphase I.
Inclusion bodies in recombinant E. coli producing human calcitonin tetramer, as visualized by immuno‐gold electron microscopy
Authors: Petrov P. , Jay E. , Ivanov I.
Published: February 2012

Inclusion bodies are described in recombinant E. coli cells harboring plasmid for the expression of a synthetic gene coding for human calcitonin tetramer. The inclusion bodies are visualized by electron microscopy and the protein is identified by immuno‐gold technique, using antibodies against synthetic human calcitonin. The diameter of the inclusion bodies is 1 micron on the average.
Stress response in Drosophila subobscura. III. Variability of heat shock puffs
Authors: Pascual L. , Latorre A. , de Frutos R.
Published: February 2012

Variability in the heat shock response has been studied in D. subobscura, both in individuals from different strains at the same moment of development and in individuals belonging to the same strain at different moments of prepupal development. The heat shock response was independent of the genic background of the individuals, whereas a variability depending on the moment of development has been obtained. In relation to this variability two kinds of heat shock puffs have been found: those induced independently of the moment of development and those induced with a response dependent on it. In both cases a differential genic response that is dependent on the temperature of treatment has been detected.
A mucus‐secreting human colonic epithelial cell line responsive to cholinergic stimulation
Authors: Roumagnac I. , Laboisse C.
Published: February 2012

The human colonic epithelial cell line Cl.16E grows in culture as a polarized monolayer which differentiates at confluency into typical goblet cells secreting their mucin content into the culture medium. Polyclonal antibodies raised against these mucins were used in an ELISA to measure the amount of mucins secreted by the Cl.16E cells. Carbachol caused a transient and significant increase in mucus secretion with a maximal stimulation occurring at 30 min. A dose‐dependent effect was found with a maximal stimulation with 10‐3M carbachol. This effect was inhibited by atropine. These results indicate that the effects of carbachol are mediated by muscarinic receptors present on mucus‐secreting epithelial cells.
Use of monoclonal antibodies to follow the phylogenic distribution of human renal antigens
Authors: Candelier J. J. , Le Pendu J. , Couillin P. , Boue A.
Published: February 2012

Nine human differentiation antigens have been defined by monoclonal antibodies (M. Abs) developed from mice immunized with embryonic kidney cells (mesonephros or metanephros of 7 week‐developmental ages). Their spatial and temporal distributions during human kidney organization were previously studied [3]. In this paper we have attempted to follow by immunofluorescence their phylogenic location, from fish to mammals. Six of them recognized the same structures as in humans: proximal convoluted tubules (PCT) (EG9.11, EG19.6, E116.1), glomerular basement membrane (GBM) (EG14.1) and extracellular matrix (EK8.1, EK17.1). However, staining was limited to certain mammals. EK17.1 has been characterized as an anti‐fibronectin. These antibodies revealed the same histological structures in the human mesonephros and metanephros. The three other antibodies revealed epitopes appearing earlier in evolution and whose histological distribution varied according to species. These antibodies stained different structures in the mesonephros and metanephros. Thus, the staining particularities observed during human renal ontogenesis were found again in the phylogenetical study.
Immunohistochemical localization of type IV collagen in mouse tooth germ: an ultrastructural study
Authors: Brisset L. , Laurent‐Maquin D. , Brossard D. , Cam Y.
Published: February 2012

Localization of type IV collagen was analyzed at the ultrastructural level in mouse embryonic molars by using a preembedding technique. Cryostat sections were incubated with type IV collagen antibody and then treated with the peroxidase‐antiperoxidase complex. This antibody was visualized at the epithelio‐mesenchymal interface. Labeling was intense and uniformly distributed throughout the basement membrane. However, it was mainly restricted to the lamina densa. No immunostaining was detectable in the lamina lucida but it was crossed by fine filaments that appeared as projections from the lamina densa to the epithelial cell plasma membrane. At the mesenchymal aspect of the basement membrane, projections of labeled material extended from the lamina densa in the underlying dental mesenchyme. At the presecretory stage of odontoblasts, these projections were in close connection with mesenchymal cell processes.
Calbindin D‐27 kDa: preferential localization in non‐B islet cells of the rat pancreas
Authors: Pochet R. , Pipeleers D. G. , Malaisse W. J.
Published: February 2012

The presence and abundance of calbindin in rat pancreatic islet cells was assessed by immunohistochemistry of either whole islets or purified B and non‐B islet cells, as well as by Western blotting of extracts derived from whole islets and purified B and non‐B islet cells. Immunohistochemistry of pancreatic sections indicated a higher calbindin content in non‐B cells, located at the periphery of the islets, than in the centrally located insulin‐producing B cells. Comparable results were obtained in purified islet cells. Likewise, scanning densitometry of the Western blots indicated that, relative to cell volume, the single calbindin band (Mr 27 kDa) was 5‐7 times higher in non‐B than in B cells. In the splenic lobe of chick pancreas, however, the opposite situation prevailed. Thus, insulin‐producing cells clustered in small roundish islets were more intensely labelled after exposure to anti‐calbindin serum than non‐B islet cells located in large and irregularly shaped islets. Nevertheless, even in the chick pancreas, non‐B islet cells contained an appreciable amount of calbindin.
Three‐dimensional electron microscopy of the nucleolus and nucleolus‐associated chromatin (NAC) during early germination of Zea mays L.
Authors: Motte Patrick , Deltour Roger , Mosen Henri , Bronchart Raymond
Published: February 2012

Nucleoli and nucleolus‐associated chromatin (NAC) of radicle cells have been three‐dimensionally reconstructed from serial ultrathin sections during early germination of Zea mays. As a preliminary, the effect of 5 methods of fixation on the ultrastructure of the active NAC were tested qualitatively and quantitatively. It appeared that paraformaldehyde best preserved the fibrillar centres (FCs) and was consequently used for the 3‐D reconstructions. In quiescent cells, the NAC forms either 2 short internal strands about 0.7 μm thick running within the nucleolus or 2 peripheral knobs of the same diameter. Whatever its morphology, the NAC was composed of one clear zone, i.e., secondary constriction (SC) of the nucleolar organizer region (NOR), and one electron‐opaque zone, i.e., heterochromatic segment (HS). During germination the NAC was always connected to the nuclear envelope (NE) by a bridge of dense chromatin. The NAC strands or knobs of the quiescent cells are likely to be the counterpart of the 2 NORs of this species. 10–12 hr after onset of germination, one or several networks of nucleolar vacuoles were formed within which the whole NAC was located. Chromatin fibers about 12 nm thick emerged from unfolding portions of the NAC within these “nucleolar chromatin dispersal vacuoles” (NCDV). At 24 hr, the NAC appeared as 2 dichotomous strands. Seventy‐two hr after germination both the stretching out and branching of the NAC were more pronounced. After 120 hr, the transcribing ribosomal genes for each NAC strand together with the newly synthesized RNP transcripts formed a layer of dense fibrillar component surrounding a thin axis which was composed mainly of pale material. Together these formed a typical plant nucleolonema.
Comparative study of molecular characteristics of X and Y nucleolar organizers of various lines of Drosophila melanogaster
Authors: Rosenberg‐Bourgin Myriam , Paumard Solange , Contesse Gérard
Published: February 2012

We have determined for the X chromosomes of 10 laboratory strains and the Y chromosomes of 4 of them both the total number of ribosomal units and the relative percentages of uninterrupted (ins‐), type 1 (ins1: with distinction between small ins1S and large ins1L) and type 2 (ins2) interrupted ribosomal units.

These studies were made with the DNA extracted from third instar larval diploid tissues (brains and imaginal discs) of X/X female lines or XNO−/Y male lineages (devoid of X ribosomal genes) whose members possess copies of the same initial X or Y chromosome.

Between the X chromosomes as well as the Y chromosomes an ⋍ 2‐fold variation was observed in the total number of ribosomal genes: from ⋍ 200 to 420 for the X chromosomes and from ⋍ 150 to 330 for the Y ones.

The Y chromosomes are devoid of insertion 1 interrupted units, but one can observe some variation in the percentage and hence the absolute numbers of uninterrupted and insertion 2 interrupted units.

Among the X chromosomes a very large variation exists between the percentage and absolute number of all the ribosomal unit types; it is to be noted especially that the number of uninterrupted units, which are the only kind of ribosomal genes actively transcribed, can vary from about 20 to 140 without any differences in the development of the different strains.
Subcellular topology of rat liver methionyl‐, leucyl‐, and arginyl‐tRNA synthetases
Authors: Amar‐Costesec Alain , Turu Christine
Published: February 2012

We have investigated the distribution of methionyl‐, leucyl‐, and arginyl‐ tRNA synthetases in primary liver fractions obtained by differential centrifugation of homogenates in isotonic sucrose: 78–93% of synthetase activities are recovered in the cytosolic fraction. Microsomes contain only 4.8%, 19.4%, and 6.4% of the methionyl‐, leucyl‐, and arginyl‐tRNA synthetases activities, respectively. This proportion increases up to 11.3%, 26.1%, and 20.7%, respectively, when the homogenization medium is supplemented the 5 mM Mg2+ and 25 mM K+. The presence of protease inhibitors in the homogenization medium does not increase the proportion of synthetases recovered in microsomes. After subfractionation of microsomes by isopycnic centrifugation, the distributions of the 3 synthetases display a peak of soluble enzyme at a density of 1.12. In addition, methionyl‐ and leucyl‐ tRNA synthetases display a second peak overlapping that of RNA. This suggests that a small proportion of these synthetases (0.7% and 5.71% of total activities, respectively) bind to the d domain of the ER. The Golgi complex, the plasma membranes, and the peroxisomes lack aminoacyl‐tRNA synthetase activity. The 3 synthetases are readily detached from membranes when intact microsomes are washed with 250 mM sucrose alone or containing 5 mM PPi, or 320 mM KCl. The binding of methionyl‐tRNA synthetases to microsomes was measured in vitro, at 4°C, with a sample of the cytosolic fraction as a source of synthetase. Microsomes stripped of their bound polysomes display a binding capacity that is not significantly different from that of unstripped microsomes. Even in the presence of cations, the amount of synthetase bound to the membranes remained low by comparison with the cytosolic content.
Does the synthesis of ribosomal RNA take place‐within nucleolar fibrillar centers or dense fibrillar components?
Authors: Rasˇka Ivan , Reimer Georg , Jarni´k Michal , Kostrouch Zdeneˇk , Rasˇka Karel
Published: February 2012

By means of immunocytochemistry performed on cryosections of cultured cells, RNA polymerase I was localized mainly to nucleolae fibrillar centers. The labelling of nucleolar dense fibrillar components was low and depended on the cell type. In contrast, DNA topoisomerase I and RNP complexes containing U3 snRNA were enriched in dense fibrillar components, their occurrence in fibrillar centers being usually much less.
Inhibition of the hydrosmotic response to antidiuretic hormone by 3,3′‐diallyldiethylstilbestrol (DADES)
Authors: Calamita G. , Bourguet J. , Hugon J.S. , Fischbarg J.
Published: February 2012

3,3′‐diallyldiethylstilbestrol (DADES), a blocker of the facilitated diffusion of glucose, was found to interfere markedly with the hydrosmotic response to antidiuretic hormone and its related agonists. Frog urinary bladders were isolated and monitored for transmural net water flow. DADES was added either to the serosal or to the apical medium at concentrations ranging from 10−4 M to 10−6 M. Pretreatment for 30 min with apical 10−4 M DADES drastically reduced the subsequent hydrosmotic response: (a) to oxytocin (4.4×10−8 M) by 91.7±17.6% versus 6.2±7.8 in control; (b) to 8‐bromo 3′,5′‐cyclic AMP by 93.5±19.4% versus 19.4±11.4%; (c) to serosal hyperosmolarity (mannitol 220 mOsm) by 99.3±0.5% versus 12.3±18.2%.

This effect was dose‐dependent. Inhibitory action of DADES was more effective on the apical side than on the serosal side (97.0±1.5 versus 45.8±10.8). Freeze‐fracture studies revealed a modified distribution of the particles and unusual endocytotic pits and vesicles in the apical membrane of both granular and mitochondria‐rich epithelial cells. These observations point to multiple and complex effects of the drug. Thus, it seems that DADES has numerous effects on urinary epithelium, which makes it a nonspecific inhibitor of water permeation. Conclusions on its use should therefore be drawn with suitable caution.
Water flow in the toad urinary bladder in response to vasopressin: role of potassium
Authors: Carvounis Christos P. , Carvounis Georgia , Bernstein Cheryl , Oros Mary E.
Published: February 2012

In agreement with previous reports, we found that absence of K+ from the serosal bath of the toad urinary bladder substantially impairs vasopressin and cAMP‐stimulated water flow. The decreased response to vasopressin appears unrelated to prostaglandin production since inhibition of endogenous prostaglandins by pretreatment with naproxen 10−5 M failed to prevent the effect seen with K+‐free Ringer's. The resistance to vasopressin does not appear to be directly related to epithelial K+ concentrations, in that maneuvers leading to decreased intracellular K+ failed to produce a similar effect. A more likely explanation appears to be that K+‐free Ringer's induces an increased cytosolic Ca++ which, in turn, decreases the hydrosmotic effects of vasopressin. Several lines of evidence argue in favor of such an explanation: (a) Increased cytosolic Ca++ had been found in other tissues with low extracellular K+; (b) The resistance to vasopressin decreases with decreased serosal Ca++; (c) The effects of K+‐free Ringer's are not additive in situations believed to have increased epithelial Ca++, i.e. replacement of serosal Na+ with choline; (d) The effects of K+‐free serosal bathing medium could be both prevented and/or reversed if already established by increasing serosal bath, and presumably intracellular, pH, which is believed to decrease intracellular Ca++.
Vasopressin‐induced intramembrane particle aggregates. A dose‐response relationship in the isolated cortical collecting duct of the rabbit kidney
Authors: Kubat B. , Lorenzen M. , Reale E.
Published: February 2012

The water permeability of collecting ducts is greatly increased by the antidiuretic hormone, vasopressin (VP). Freeze‐fracture studies were carried out to test if this permeability increase is associated with the appearance of intramembrane particle (IMP) aggregates and whether increased doses of VP lead to an increase in the number and size of particle aggregates in the luminal membrane of principal cells in the isolated cortical collecting duct. Unstimulated cells expressed 17±6.5 particle aggregates per 100 μm2. Stimulation with VP at concentrations of 20 or 200 μU/ml increased the number of particle aggregates significantly to 129±15.8 and 324±45.8, respectively. The size of the particle aggregates increased from 0.0012 μm2 under control conditions to 0.025 μm2 at 20 μU/ml VP and to 0.063 μm2 at 200 μU/ml VP. In addition, the total area occupied by the IMP increased from 0.02 μm2/100 μm2 (controls) to 3.17% and 20.38% (after 20 and 200 μU ADH/ml, respectively). Particle aggregates were also observed in the luminal plasma membrane of isolated collecting ducts fixed immediately after dissection, resembling the in vivo status. These results demonstrate that a dose‐dependent relationship exists between the concentration of the applied VP and the number of particle aggregates, as well as the size of the aggregates. Cytoplasmic tubular vesicles in fusion with the apical membrane were observed.
A method of isolation of apical membranous sheets from frog urinary bladder epithelium by stripping with gelatin
Authors: Favard Pierre , Favard Nina , Zhu Qian Long , Bourguet Jacques , Lechaire Jean‐Pierre
Published: February 2012

We have developed a techique for recovering apical membranous sheets from aphibian urinary bladders by gelatin stripping. The tissue is mounted on a lucite support and the apical surface is first stuck onto a gelatin‐coated glass slide at 30°C. This sandwich is then chilled on ice and the bladder is pulled away from the slide. Preliminary results indicate that this simple technique could be used to remove membranous apical sheets of various sizes, almost devoid of cytoplasmic contamination and without significant damage to the underlying cell structures. The method could also be adapted to prepare perforated cells and to study the cohesive forces between the different layers of the tissue.
Stimulation by aldosterone of a conductive chloride pathway in toad skin
Authors: Crabbe J. , Beaujean V. , Devuyst O.
Published: February 2012

As a rule, chloride movement (JCl−) across amphibian skin is considered to be passive; this is implied in fact for preparations incubated in Ringer's fluid, since short‐circuit current (Isc) is the quantitative expression of net, active sodium transport (JNa+). The nature of the Cl− pathway(s) was investigated by incubating amphibian skin (mostly Bufo marinus) with Cl− present on the epithelial side only, and after blocking JNa+ by combined treatment with ouabain and amiloride. In such conditions, JCl− was found to be equal to (reversed) Isc; furthermore, when JCl− was “translated” in terms of conductance, gCl−, the latter accounted almost quantitatively for transepithelial conductance, gt. When residual intratissue (i.e. intracellular) electronegativity was eliminated by replacing Na+ with K+, JCl− was larger but Isc and JCl− were still found to reflect each other, and gCl− again accounted for most, if not all, of gt. JCl− in the opposite direction, as a result of Cl− being present only on the dermal side, was negligible, and gt was very low.

Thus, in the absence of sodium transport, when experimental conditions are such that a net inward JCl− obtains, the anion apparently flows only through (a) conductive pathways(s). Aldosterone is probably involved in the regulation of this pathway, as JCl− was much lower when toads were maintained in dilute saline than in water or on moist peat; so was the fraction of the apical surface corresponding to mitochondria‐rich cells.
Fluorescence labeling of proteins related to ADH‐induced change in frog bladder luminal membrane
Authors: Valenti Giovanna , Guerra Lorenzo , Casavola Valerua , Svelto Maria
Published: February 2012

Sulfhydryl (SH) reactive reagents, such as cosin derivatives, have been found to be useful in labelling water pathways in red cells. In the present study we used an impermeable SH‐reagent, a fluorescent maleimide analogue EMA (eosin‐5′‐maleimide), in order to identify proteins involved in water permeability response to antidiuretic hormone (ADH).

We observed that: 1) EMA (1 mM) mucosal pretreatment did not modify either the basal water flux or the subsequent ADH‐induced hydrosmotic response; 2) EMA added to the mucosal bath at the maximum response to ADH, significantly decreased net water flux by about 40%; similar results were obtained when 10−5 M forskolin was used as a hydrosmotic agent. These results suggest that the inhibitory effect of EMA occurs at a post cAMP step, possibly at the level of the sulfhydryl groups of the water channels themselves.

Fluorescence distribution in SDS‐PAGE of Triton X‐100 extracted proteins from bladder labeled with EMA in both control conditions and under ADH stimulation allowed us to identify apical membrane proteins, labeled during ADH stimulation and not labeled in water impermeable controls. Of particular importance are four proteins of 52, 32–35, 26, 17, kDa. These polypeptides are probably involved in ADH‐stimulated water transport and may be components of the water channels.
Are close contacts between astrocytes and endothelial cells a prerequisite condition of a blood‐brain barrier? The rat subfornical organ as an example*
Authors: Bouchaud Claude , Le Bert Marc , Dupouey Pierre
Published: February 2012

The microvessels of the rat subfornical organ (SFO) are heterogeneous: those of the caudal part lack a blood‐brain barrier (BBB) unlike those of the rostral part. The astroglial environment of these microvessels has been studied by combining an immunocytochemical technique employing an anti‐GFAP (glial fibrillary acidic protein) antiserum with the morphological detection of a barrier to the protein‐silver complex.

All the SFO microvessels are surrounded by astrocytes characterized by a tumescent aspect; however, the relative proximity between the astrocytic feet and the endothelial cells varies considerably. The capillaries provided with a barrier (rostral SFO) are contiguous with the astrocytes from which they are only separated by a basement membrane. The capillaries devoid of BBB (caudal SFO) are surrounded by a pericapillary space that keeps the astrocytes at a short distance (capillaries with a very rich vesicular entothelium) or at a long distance (capillaries with a fenestrated endothelium).

The astrocytes are absent in the choroid plexus where all microvessels are fenestrated and lack a barrier.

These data suggest that the astrocytes release one or more signals which in their vicinity inhibit the expression of endothelial morphological characteristics (fenestrations, vesicles) responsible for the leakage of plasmatic proteins from the blood to the cerebral parenchyma of the circumventricular organs.