bluuebunny/crossref_metadata_2025 huggingface dataset:
Membrane control of ciliary movement in ciliates
Authors: Andrivon Claude
Published: February 2003

Summary— Ciliary movement is generated in the axoneme by the unidirectional sliding of the outer doublets of microtubules produced by the adenosine triphosphate (ATP)‐energized dynein arms. It is composed of an effective stroke phase and a passive recovery stroke phase. Two parameters are modulated to determine the swimming characteristics of the cell (speed and direction): (i) beat frequency; (ii) direction of the effective stroke.

They are linked to the internal Ca++ level and to the membrane potential. The membrane governs the internal Ca++ level by regulating Ca++ influx and efflux. It contains voltage‐sensitive Ca++ channels through which is passive Ca++ influx, driven by the electrochemical gradient, occurs during step depolarization. The rise of the Ca++ level, up to 6.10−7M triggers ciliary reversal and enhances beat frequency. Ca++ is extruded from cilia by active transport. Ca++ also activities a multistep enzymatic process, the first component of which is a membrane calmodulin‐dependent guanylate cyclase. cGMP interacts with Ca++ to modulate the parameters of the ciliary beat. The phosphorylation‐ dephosphorylation cycle of axoneme and membrane proteins seems to play a major role in controlling ciliary movement.

Hyperpolarization of the membrane enhances beat frequency by an unknown mechanism. It could be a modification of the ratio of axonemal bound Ca++ and Mg++, or activation by cyclic adenosine monophosphate (cAMP) produced by a membrane adenylate cyclase.

The ciliary membrane behaves as a receptor able to detect modifications of external parameters, and as a transductor transmitting the detected signal by second or third messengers toward the interior of the cilia. These messengers, acting at different levels, modulat the parameters of the mechanism that generates ciliary movement.
The flagellar apparatus of spermatozoa in fish. Ultrastructure and evolution
Authors: MATTEI Xavier
Published: February 2003

Chondrichthyes posses an evolved type of spermatozoa. Their flagellar apparatus is characterized by the presence of flagellar roots which form the axis of the midpiece, and the existence of one or two lateral elements associated with the axoneme, Osteichthyes, mainly teleosteans, show a great diversity of spermatic forms. The primitive spermatozoon with a 9+2 pattern flagellum is common. The primitive spermatozoon has evolved along different lines. The spermatic diversity which results from this is mainly evident in the structure of the flagellar apparatus. In the animal kingdom the primitive spermatozoon with a 9+2 pattern flagellum, present in primitive metazoa, is retained in phyla where external fertilization is maintained. The main evolutionary tendencies – elongation, aflagellarity or biflagellarity – are generally connected with the acquisition of internal fertilization. These evolutionary tendencies are found in teleosteans. It is not Possible to link aflagellarity or biflagellarity of the gamete in certain fishes to this method of fertilization. Only the elongation of the spermatozoon is connnected, in certain cases, with interanl fertilization, but this cannot be taken as general.
Organization and functions of cytoskeleton in metazoan ciliated cells
Authors: Sandoz Daniel , Chailley Bernadette , Boisvieux‐Ulrich Emmanuelle , Lemullois Michel , Laine Marie‐Christine , Bautista‐Harris Guillermina
Published: February 2003

Summary— Ciliated cells are characterized by a highly organized cytoskeleton which is connected with the ciliary apparatus. The organization of microtubules, microfilaments, and cytokeratin filaments is described and the relationships of each network with the ciliary apparatus are emphasized. Possible functions of such a complex cytoskeleton are discussed.
Development and functions of the cytoskeleton during ciliogenesis in metazoa
Authors: Lemullois Michel , Boisvieux‐Ulrich Emmanuelle , Laine Marie‐Christine , Chailley Bernadette , Sandoz Daniel
Published: February 2003

Summary— The different steps of ciliogenesis occurring in quail oviduct were compared to the ciliogenesis pattern described in other metazoan species.

Centrioles are generated according to pathways that are found within the same cell: the centriolar and the acentriolar pathways. In the acentriolar pathway, centrioles are generated in the Golgi area, without contact with the preexisting centrioles of the centrosomes, and they migrate toward the apical membrane. The control of this polarized migration was studied by means of several drugs (colchicine, nocodazol, taxol, cytochalasin D, benzodiazepines) and immunocytochemistry.

It was suggested that an actin‐myosin system was involved in the migration of centrioles, whereas labile microtubules were not necessary.

Basal bodies must dock with plasma membrane or cytoplasmic vesicles for the initiation of axonemal microtubule polymerization. This signal is necessary even in the presence of taxol.
Molecular heterogeneity of the isolated surface glycoprotein from variant AnTat 1.1 of Trypanosoma brucei brucei
Authors: Boutignon Franc¸ois , Hublart Marylène , Gomes Véronique , Mendonca‐Previato Lucia , Tetaert Daniel , Huet‐Duvillier Guillemette , Degand Pierre
Published: February 2003

Variant surface glycoprotein (VSG) of Trypanosoma brucei brucei AnTat 1.1 was released by means of the procedure described by Baltz et al. ([1976], Ann. Immunol. [Inst. Pasteur] 127C, 761–774). The concanavalin‐A chromatography yielded 3 VSG fractions according to the addition, in the elution buffer, of α‐methyl‐d‐mannopyranoside, β‐mercaptoethanol, and sodium dodecyl sulfate. These VSG fractions showed heterogeneous behaviour on reverse‐phase high performance liquid chromatography. The 3 VSG fractions as well as the myristylated VSG of AnTat 1.1 essentially consist of dimer VSG forms linked through a disulfide bridge, as judged by sodium dodecyl sulfate polyacrylamide gel electrophoresis, under reducing and nonreducing conditions.
ATP‐independent DNA topoisomerase II as potential drug target in trypanosomes
Authors: Douc‐Rasy Sétha , Riou Jean‐Franc¸ois , Ahomadegbe Jean‐Charles , Riou Guy
Published: February 2003

Two categories of trypanosomal type II topoisomerases have been isolated from trypanosomes: one is unique since it is able to realize DNA topoisomerization reactions in the absence of ATP, in contrast to the other enzyme and mammalian topoisomerase II. The biochemical properties of ATP‐independent topoisomerase II from Trypanosoma cruzi are described in this report. The enzyme can decatenate trypanosome kinetoplast DNA networks, catenate supercoiled DNA molecules, unknot P4 phage DNA, and cleave double‐stranded DNA. The enzyme is inhibited by various classes of drugs and is more sensitive than mammalian topoisomerase II. Therefore, trypanosome ATP‐independent topoisomerase II provides a potential target for chemotherapy.
Protein p126: a parasitophorous vacuole antigen associated with the release of Plasmodium falciparum merozoites
Authors: Delplace Patrick , Bhatia Aruna , Cagnard Maryvonne , Camus Daniel , Colombet Guy , Debrabant Alain , Dubremetz Jean‐Franc¸ois , Dubreuil Nicole , Prensier Gérard , Fortier Bernard , Haq Afrozul , Weber James , Vernes Alain
Published: February 2003

The p126 protein is synthesized by P. falciparum between the 32nd and the 36th hour of the erythrocytic cycle, and is localized in the parasitophorous vacuole. It is processed when schizonts rupture and the major fragments (50, 47 and 18 kDa), which are released into culture supernatant, have been characterized using monoclonal antibodies. The 47 kDa fragment has been mapped at the N‐terminus of the molecule. The portion of the protein p126 gene coding for this fragment contains 3 introns and is characterized by a sequence coding for 6 repeats of 8 aminoacids and by repeats of TCA/T‐AGT coding for a polyserine sequence of 37 serines in a row for the FCR‐3 strain. The 50 kDa fragment is also found in culture supernatant when merozoites are released from mature schizonts. The incubation of mature schizonts with leupeptin inhibits the release of merozoites and, in this case, a 56 kDa intermediate product is found. In those conditions, merozoites were observed free in the erythrocyte cytoplasm, the membrane of the parasitophorous vacuole being destroyed. The 50 kDa fragment can be obtained from the 56 kDa fragment by treatment with trypsin (a protease inhibited by leupeptin). Our results suggest that the processing of the 56 kDa fragment: 1) is protease‐dependent, and could depend on a trypsin‐like activity; 2) cannot occur after the release of merozoites because of the protease inhibitors contained in the serum; 3) does not occur before the release of merozoites, since no processed products of the protein p126 are observed in unruptured schizonts. Saimiri sciureus monkeys were immunized with purified p126 antigen adsorbed on aluminum hydroxide, splenectomized and challenged with P. falciparum. A spontaneous recovery without treatment was observed for 2 out of the 3 immunized monkeys. We investigated the mechanisms responsible for the protective immunity and it appeared that cellular effector mechanisms are probably involved.
Neutral proteases involved in the reinvasion of erythrocytes by Plasmodium merozoites
Authors: Schrevel Joseph , Grellier Philippe , Mayer Roger , Monsigny Michel
Published: February 2003

Neutral proteases of Plasmodium sp erythrocytic stages were studied by means of a sensitive fluorogenic method and gelatin‐SDS‐PAGE. The substrates gluconoyl‐Val‐Leu‐Gly‐Lys(or Arg)‐3‐amido‐9‐ethylcarbazole were selectively hydrolyzed by an endopeptidase from rodent Plasmodium berghei (Pb) and Plasmodium chabaudi (Pc) and from human Plasmodium falciparum (Pf) parasites. These endopeptidases were purified from 100,000‐g soluble schizont extract by high pressure liquid chromatography; they have a similar Mr of 68,000 in SDS‐PAGE, and an optimal activity at pH 7.4. The Pb 68 and Pf 68 endopeptidases were localized in shizonts and also in merozoites as shown by indirect immunofluorescence on Pb merozoites and by the identification of the Pf68 endopeptidase activity in free viable merozoites. The Pb68 and Pf68 endopeptidases belong to the class of cysteine proteases. Analysis by gelatin‐SDS‐PAGE of a Pb 68 endopeptidase‐enriched fraction showed a reproducible 95,000 proteolytic band. The initial extracts showed a similar 95,000 proteolytic band, and also 2 other 90,000 and 85,000 major bands. During reinvasion experiments, it was possible to recover a 95,000 and a 40,000 protease band from supernates of cultures grown in a semidefined medium without serum. Hydrophilic peptide derivatives related to the substrate of Pf 68 endopeptidase are shown to be potential inhibitors of the Pf reinvasion process in vitro.
Culture of proliferating and differentiating fat‐storing cells in 3T3‐conditioned medium
Authors: MENDOZA‐FIGUEROA Tomás , Arg¨ello Carlos , KURI‐HARCUCH Walid
Published: February 2003

There is growing evidence suggesting that hepatic fat‐storing cells (FSC) or Ito cells have an important function in vitamin A storage and metabolism and in the synthesis of connective tissue components in normal liver and during fibrogenesis. The purified FSC acquire a fibroblastic morphology and their vitamin A content decreases in culture. We cultivated cells under in vitro conditions that allowed the expression of FSC morphological and functional characteristics for 3–4 weeks of primary culture. Cells were isolated from rat liver by the collagenase‐perfusion method without further purification and cultured with 3T3‐conditioned medium, which seemed to stimulate the selective proliferation of the FSC. After 8–10 days, round and stellate cells grew actively from a few precursor cells in the primary culture and were not subcultivated; the stellate cells had the ability to become round and vice versa and were highly motile. The cells had intracytoplasmic lipid droplets, a well developed rough endoplasmic reticulum, Golgi complex, numerous vesicles filled with electron‐dense material, and extracellular matrix (ECM) components on their surface. Both stellate and round cells showed the presence of desmin by immunofluorescence and vitamin A autofluorescence, but lacked peroxidase activity. The culture conditions we describe allowed the selective proliferation of cells with morphological and functional characteristics of the FSC in the normal liver, raising the possibility of studying FSC proliferation and differentiation.
Ultrastructural identification of round‐granule EC cells in rabbit fundic mucosa
Authors: PRADAL Gilbert , LEFRANC Gérard , PILOQUET Philippe , Huong Ngoc VO , RIET Anne
Published: February 2003

In endocrine (EC) cells of rabbit fundic mucosa, it is practically impossible to obtain unequivocal ultrastructural identification of all cells found in order to perform morphometric analysis. In addition to classic EC cells with pleomorphic granules, a cell type with entirely round granules is encountered which can be confused with non‐EC cells. To solve this problem, all EC cells in our study were first identified by their 5‐HT (immunocytochemistry) and argentaffinity. Examination of the fine structures of reactive cells then revealed that the round granules of EC cells were differentiated from those of non‐EC cells by the existence of a dense core surrounded by a less dense halo, a feature providing unequivocal ultrastructural identification. EC cells with round granules showed less argentaffinity and less immunoreactivity to 5‐HT as compared with classic EC cells. After labelling with [3H]L‐dopa, EC cells with round‐granules displayed an overall staining index higher than that of classic EC cells and comparable with that of D cells; however, the nuclear staining index was higher than that of D cells.
SYNTHESIS OF MELATONIN BY THE PINEAL MODIFIED PHOTORECEPTORS OF BIRDS IMMUNOCYTOCHEMICAL LOCALIZATION OF HYDROXYINDOLE‐O‐METHYLTRANSFERASE
Authors: GUERLOTTE Jérôme , VOISIN Pierre , BRISSON Paul , FAURE Jean‐Pierre , COLLIN Jean‐Pierre
Published: February 2003

Photoperiodic control of several biological rhythms is exerted through the inhibitory effect of light on melatonin synthesis in the pineal organ. Hydroxyindole‐O‐methyltransferase (HIO‐MT), the last acting‐enzyme in melatonin biosynthesis, constitutes a specific marker of melatoninergic cells. In the present study, an antibody directed against chicken HIOMT was affinity‐purified and used to identify melatoninergic cells in the pineal organ of chicken, quail, sparrow and blackbird. Regardless of the species, intense immunocytochemical reactions were observed in modified photoreceptors, whereas other cellular constituents (mostly glial cells) remained unlabeled. We conclude that modified photoreceptors synthesize melatonin in the avian pineal gland and are thus accountable for the translation of the photoperiodic input into hormonal output.
ULTRASTRUCTURAL LOCALIZATION OF ARGYROPHILIC PROTEINS IN NUCLEOLI OF ZEA MAYS BY TWO SILVER STAINING TECHNIQUES
Authors: MOTTE Patrick , MOSEN Henri , BRONCHART Raymond , DELTOUR Roger
Published: February 2003

Summry—

Ag staining was applied on interphasic nucleoli of Zea mays root cells 120h after germination. We applied the two‐step Ag‐NOR staining technique to small root fragments and the one‐step technique to sections of Lowicryl‐embedded tissue. The small‐sized silver grains were mainly located in the dense fibrillar component (DFC). The unstained fibrillar centers (FCs) differed in their proteinic contents from the NOR (which is positively silver stained) and were not the interphasic NOR counterpart.
EXPRESSION OF THE c‐fos PROTO‐ONCOGENE IN BONE, CARTILAGE AND TOOTH FORMING TISSUES DURING MOUSE DEVELOPMENT
Authors: CAUBET Jean‐François , BERNAUDIN Jean‐François
Published: February 2003

Summry—

The c‐fos proto‐oncogene is the cellular homologue of v‐fos identified as the bone transforming gene of the FBJ and the FBR murine osteosarcoma viruses. We show here, using a sensitive in situ hybridization method, that the c‐fos proto‐oncogene is expressed in the cartilage, bone and tooth forming tissues during mouse development. This result suggests that the tumors observed after infection by the FBJ viral complex and c‐fos overexpression in transgenic mice occur in those tissues in which c‐fos is expressed during development.
Vasopressin‐induced changes in receptor‐mediated endocytosis of asialoglycoprotein in rat hepatocytes
Authors: Gil‐Falgon Sophie , Lamaze Christophe , Feger Jeanne
Published: February 2003

Summary— The ability of second messengers to modulate receptor‐mediated endocytosis was studied on isolated rat hepatocytes. A 20‐min preincubation with vasopressin was used as a modulation. We observed a 20% inactivation of both surface and intracellular receptors, with no change in the affinity of those remaining active. The internalization and dissociation of a synchronous wave of ligand was not affected, but its degradation was partially inhibited. Our observations suggest that second messengers such as intracellular calcium and diacylglycerol play a complex role in the intracellular trafficking associated with endocytosis.
Modulations of the epithelial phenotype and functional activity of cultured bovine tracheal gland cells: dependence on the culture medium and passage number
Authors: Benali Rachid , Dupuit Florence , Chevillard Martine , Jacquot Jacky , Haye Bernard , Puchelle Edith
Published: February 2003

Summary— Bovine tracheal gland (BTG) cells in culture show an epithelial‐fibroblastoid transition after several passages. To investigate these BTG cell phenotype changes, we studied the effects of both the culture medium and passage number on the expression of epithelial cytoskeletal proteins and glandular serous cell markers. We also analyzed the intracellular cAMP level in the basal state and after adrenergic stimulation. Three culture media were used: 1) serum‐free defined medium (SFDM); 2) medium supplemented with 2% Ultroser G; and 3) medium supplemented with 10% fetal calf serum (FCS). Using immunofluorescence microscopy, we showed that, in the first 4 passages whatever the culture conditions, BTG cells expressed immunoreactivities to cytokeratin filaments and desmoplakins I and II, whereas vimentin filaments were not detected. After four passages, BTG cells cultured in 10% FCS or 2% Ultroser G became progressively fibroblastoid and showed immunoreactivities to both vimentin and cytokeratin intermediate filaments. No immunoreactivity to vimentin filaments was observed on BTG cells cultured in a SFDM. Using biochemical analysis, we showed that basal levels of cAMP in cultured BTG cells and lysozyme secretion by these cells vary according to the culture medium and passage number. It was higher in BTG cells cultured in a SFDM compared to that recovered from cells cultured in medium supplemented with Ultroser G or FCS. Whatever the culture medium, BTG cells responded to stimulation by isoproterenol. However, the results of stimulation in a SFDM were higher than in Ultroser G or FCS supplemented medium. We conclude that the BTG epithelial cell organization and the regulation of biosynthesis of secretory proteins by these cells in culture depend on both the culture medium and passage number. The maintenance of the epithelial serous phenotype of BTG cells during the first passages (1 to 4) suggests that the study of the regulation of these gland cells should be limited to these early passages.
Lipid trafficking between high density lipoproteins and Babesia divergens‐infected human erythrocytes
Authors: Valentin Alexis , Rigomier Daniel , Précigout Éric , Carcy Bernard , Gorenflot André , Schrével Joseph
Published: February 2003

Summary— A two‐fold increase in the amount of phospholipids was observed in Babesia divergens infected human red blood cells. In vitro incubation with [32P]‐phosphorus and [3H]‐glycerol demonstrated that B divergens has the ability to synthesize the phospholipid backbone. On the other hand, the low incorporation of [14C]acetate indicated the absence of a de novo fatty acid synthesis and suggested the necessity of an exogenous lipid source for the parasite. Several intra‐erythrocytic growth cycles of B divergens could be achieved in vitro, using a serum‐free medium supplemented only with fractions of human high density lipoproteins (HDL). At an HDL concentration of 0.5 mg/ml (protein concentration) and with a 1% starting parasitaemia, parasite growth was similar to that observed under standard culture conditions with 10% human serum, at least for the first 24 h, a time equivalent to three parasite erythrocytic life‐cycles. Lipid transfer from HDL to the intra‐erythrocytic parasites was demonstrated by uptake and exchange of fluorescent NBD‐phosphatidylcholine (NBD‐PC) loaded HDL at different temperatures. Kinetic experiments with [3H]‐oleyl‐PC‐loaded HDL demonstrated a unidirectional transfer of lipids from radiolabelled HDL to the parasite; partial conversion of PC to phosphatidylethanolamine (PE) was also observed. In the semi‐defined medium, the HDL fraction appeared to be the major source of lipids for the growth of B divergens in human erythrocytes.
Comparative analysis of four parameters involved in puffing activity along chromosome arm 2L of D melanogaster
Authors: Visa Neus , Díez Joséluís , Santa‐Cruz M. Carmen
Published: February 2003

Summary— Autoradiographic and immunofluorescent techniques have been used to analyse the relationship between puffing, transcription and occurrence of DNA/RNA hybrids in D melanogaster salivary gland chromosome 2L. Experiments of 3H‐uridine incorporation have indicated that similar rates of RNA synthesis are observable in well developed puffs as well as in some diffuse bands and interbands. On the other hand, puffs of similar size incorporate 3H‐uridine at quite different rates. The presence of RNA polymerase II seems to follow a coincident pattern with that of 3H‐uridine incorporation. Our results indicate that the rate of transcription does not determine either the formation of a puff or its potential size. Instead, we have found a positive correlation between the amount of DNA/RNA hybrids and puff size, independently of the transcription rates. Transient accumulation of transcribed RNAs in their chromosomal compartment could therefore play a relevant role in the determination of puff size.
Quantitative immunolocalization of four immunodominant antigens of Toxoplasma gondii
Authors: Boulanger Florence , Bonhomme Annie , Lebonvallet Stéphane , Bonnet Noël , Pluot Michel , Pinon Jean‐Michel
Published: February 2003

Summary— Ultrastructural localization of four immunodominant antigens of Toxoplasma gondii was investigated quantitatively on thin sections and replicas by an immunogold technique using four monoclonal antibodies (Mab). On immunoblot Mab IV47, GII9, II38 and IE10 identified proteins of 28, 30, 45 and 66–70 kDa, respectively. Use of digital image analyzer and a semi‐automatic procedure developed by us, the patterns of label distribution were compared in three cell structures: cell surface, submembrane area and rhoptries. On the whole cell surface, protein P28 and P30 were 2.5 and 4 times more abundant than P66–70 respectively. The protein P28 was essentially concentrated in the submembrane area with a labeling of 195.4 ± 46.7 gold particles/μm2 that follows a decreasing gradient from this area to the cell centre. In the rhoptries, all four antigens were detected, P45 and P66–70 being major with a labeling of 97.1 ± 31.1 gold particles/μm2 and 155.1 ± 39.3 gold particles/μm2 respectively. The results support the hypothesis that rhoptries are the essential site for antigen storage.
Neurosteroids: a new function in the brain
Authors: Baulieu Étienne‐Émile
Published: February 2003

Summary— “Neurosteroids” accumulate in the central nervous system independently of supply by peripheral endocrine glands. Dehydroepiandrosterone (DHA) and pregnenolone (Δ5P) were first found in the rat brain. Then, a steroid biosynthetic pathway was demonstrated in oligodendrocytes, mostly by enzyme immunocytochemistry and biochemical studies in primary cultures of glial cells, where the formation, from appropriate radioactive precursors, of Δ5P, Δ5‐pregn‐3β,20α‐diol (20α‐DHΔ5P), progesterone (P), 5α‐pregnane‐3, 20‐dione (5α‐DHP) and 3α‐hydroxy‐5α‐pregnane‐20‐one (3α, 5α‐THP), as well as estrogen‐induced progesterone receptor (PR) was observed. Several biological effects of neurosteroids have been observed, such as electrical stimulation of neurones, involvement in behavioral activities, modulation of GABAA‐receptor (GABAA‐R) function (potentiated by 3α,5α‐THP and its 21‐hydroxyderivative, antagonized by Δ5P‐ and DHA‐sulfates) and growth/differentiation of glial cells in vitro. Preliminary findings suggest that the neurosteroid concept applies to all mammalian species, including man. Further investigations should assess the pathophysiological significance of the synthesis of neurosteroids and decipher their mechanisms of action via nuclear and membrane receptors.
Glucose‐6‐phosphatase activity of endoplasmic reticulum and Golgi apparatus in spermatocytes and spermatids of the rat: an electron microscopic cytochemical study
Authors: Thorne‐Tjomsland Gro , Clermont Yves , Tang Xueming
Published: February 2003

Summary— The glucose‐6‐phosphatase (G6Pase) activity of cytoplasmic components of spermatocytes and spermatids of the rat was examined by electron microscope cytochemistry using cerium chloride as a capture agent. G6Pase activity, a recognized ER‐resident enzyme, was present in all ER cisternae of spermatocytes. In spermatids, while some ER cisternae were G6Pase‐reactive, others were negative or only slightly reactive, indicating an unequal distribution of the enzymatic activity throughout the network of ER cisternae in these cells. In spermatocytes, the cis‐ and trans‐elements of the stacks of Golgi saccules were slightly but significantly reactive for G6Pase. In the Golgi apparatus of spermatids, the cis‐element, 4 or 5 underlying saccules, as well as one or two thick trans Golgi elements were G6Pase reactive. The G6Pase activity of the various Golgi elements, like that of the ER cisternae was not affected by the pH of the medium and was completely inhibited by Na‐vanadate, a known G6Pase inhibitor. Sertoli and Leydig cells, submitted to the same cytochemical conditions, showed complete G6Pase reactivity of their ER; however in Sertoli cells, all Golgi components were consistently negative while in Leydig cells the cis‐ and trans‐elements of the Golgi stacks were slightly reactive, as in spermatocytes. Thus, the G6Pase reactivity of Golgi elements, appeared variable from one cell type to another. The compact juxtanuclear Golgi apparatuses of spermatocytes and spermatids were both associated with numerous G6Pase reactive ER cisternae; some were present at their surface, others crossed their cortices between Golgi stacks and formed elaborate networks in their cores. Other ER cisternae, in turn were closely apposed to or intertwined with trans‐elements of the Golgi stacks, a relationship raising the possibility of molecular exchanges at this pole of the stacks in germinal cells.
Mitochondrial maturation during neuronal differentiation in vivo and in vitro
Authors: Cordeau‐Lossouarn Laurence , Vayssière Jean‐Luc , Larcher Jean‐Christophe , Gros François , Croizat Bernard
Published: February 2003

Summary— The evolution of the mitochondrion has been followed within differentiating neuronal cells, both in primary cultures of neurons from fetal rat cortex and during rat brain cortex maturation. Changes in total mitochondrial proteins (mt‐proteins) were evaluated, and qualitative changes in the mt‐proteins pattern were analyzed using the Western blot technique. The evolution of mt‐protein contents in cultured neurons resembles what is observed during rat brain maturation. The mitochondrion exhibits pronounced changes in the course of neurogenesis, in particular, bursts of mitochondrial masses accompanying the successive steps of neurogenesis are observed. There are indications that protein equipment of mitochondria during neuronal development undergoes variations. Although more work is required to establish the significance of these correlations, the present data might suggest an important role of the mitochondrion in neurogenesis.
Precursors of neuropeptides in the marine worm Nereis diversicolor. In vitro translation of a precursor related to human prepro‐cholecystokinin and immunolocalization of this precursor in the nervous system
Authors: Guissi‐Kadri Sanae , Dhainaut‐Courtois Nicole , Porchet Maurice , Curgy Jean‐Jacques
Published: February 2003

Summary— Total mRNA extracted from the brain of a marine worm, Nereis diversicolor, were in vitro translated using 2 cell‐free systems: rabbit reticulocyte lysate and wheat germ extract. Among numerous products newly translated in both systems, only one class of 70 kDa polypeptides immunoprecipitated when we used a mixture of 3 well defined antibodies raised against known sequences of the human prepro‐CCK. At the cellular level, using immunocytochemistry techniques, strong and moderate immunoreactivities were seen in perikarya located in various ganglionic nuclei of the worm brain. Immunoreactive nerve fibres were visible in the neuropile but not in the infracerebral region, a neurohemal area. Immunoreactions also appeared on perikarya located in the anterior and medial groups of the ventral nerve cord. Furthermore, immunolabeled cells were observed in the midgut. Interestingly, several colocalizations of materials immunologically related to human prepro‐CCK and CCK/gastrin were observed in the brain and the ventral nerve cord both in perikarya and in nerve fibres. We propose that, in Nereis a polypeptide (molecular mass 70 kDa) is the large precursor of molecules related to those of the CCK/gastrin peptide family.
Eosinophil granulocytopoiesis in hepatic periovular granulomas during the chronic phase of experimental murine Schistosomiasis mansoni
Authors: Geuskens Maurice , Borojevic Radovan , Van Gansen Paulette
Published: February 2003

Summary— We have observed in hepatic periovular granulomas of C3H mice infected with Schistosoma mansoni, in the chronic phase of the disease (12–19 weeks of infection), groups of early precursors and immature eosinophil granulocytes corresponding, at the ultrastructural level, to promyelocytes and myelocytes. Mitosis also seen in eosinophil myelocytes. These eosinophil myeloid foci were observed in close contact with macrophages and epithelioid cells, and they were surrounded by an extracellular matrix, rich in collagen fibres. These morphological observations give support to the concept of a peripheral proliferation of cosinophils in chronic schistosomiasis, mediated by a factor secreted by macrophages present in granulomas.
Ultrastructural similarity in landmark loops of amphibian lampbrush chromosomes
Authors: Bonnanfant‐Jais Marie‐Louise , Penrad‐Mobayed May , Angelier Nicole
Published: February 2003

Summary— Simultaneous transmission and scanning electron microscopy studies were performed on lampbrush chromosomes of Notophthalmus viridescens and Xenopus laevis. The organization of their normal and landmark loop ribonucleoprotein (RNP) matrices was compared to that of Pleurodeles waltl lampbrush loops, previously described. Ultrastructural observations clearly showed that in the three species, the RNP matrix of normal and landmark loops displayed a common basic structure: an RNP fibril packed into tightly juxtaposed RNP particles of remarkably uniform size, ie 30 nm. Furthermore, analysis of the spatial arrangement of these constitutive RNP fibrils allowed us to establish ultrastructural similarities between the different types of loop matrices of the three species studied. Thus, granular loops with the same organization were found to be present in the three species, whereas Pleurodeles was the only one to exhibit, in its lampbrush chromosomes, the typical globular matrices previously described. “Sequential labelling loops” of Notophthelmus were shown to be similar of both “convoluted dense loops” of Xenopus and “dense loops” of Pleurodeles.
An helicoidal structure surrounding the cilium axoneme: Visualization by the monoclonal antibody CC‐248
Authors: Bautista‐Harris Guillermina , Klotz Catherine , Bordes Nicole , Sandoz Daniel
Published: February 2003

Summary— Monoclonal antibody CC‐248 labels cilia differentially on Triton X‐100 permeabilized ciliated epithelium of quail oviduct by indirect immunofluorescence. On isolated ciliated cells, a punctuated staining is seen at the distal region over the bend of cilia. Electron micrographs of immunoperoxidase and immunogold techniques showed that the punctuated fluorescence corresponds to a helical disposition of CC‐248 antigenic sites. This labeling was arranged on the axonemal distal region either as a simple or a double helix externally disposed around the nine microtubular doublets. These results suggest the existence of a detergent insoluble structure in the ciliary matrix that might concern the ciliary skeleton, probably acting as an elastic recoil that keeps the structural integrity of the axoneme during bending. The cross‐reactivity of CC‐248 MAb with the intermediate filament cytoskeleton of ciliated and smooth muscle cells indicates that this structure might be related to the intermediate filament family.
Spermatozoa and relationships in palaeognath birds
Authors: Baccetti Baccio , Burrini Anna Giselda , Falchetti Elisabetta
Published: February 2003

Summary— In this paper the authors describe the ultrastructure of the mature spermatozoon and the spermatid in Struthio camelus and Dromaius novaehollandiae. The first species is characterized by a rod‐like foratorium within an endonuclear canal in the anterior third of the nucleus, while the second is characterized by an extremely reduced completely extranuclear perforatorium. Other differences are in the sperm dimensions, the number of mitochondria and the length of the axonemal accessory fibers. Considering both the present data and previous findings, Palaeognath birds appear to be a peculiar and monophyletic group, characterized by: 1), a conical acrosome surrounding the nucleus; 2), a fibrous sheath aroundmost of the axoneme; and 3), an elongated distal centriole occupying the entire midpiece. Within this group, Tinamiformes seem to be more primitive than Struthioniformes. In the latter order Dromaius is distinctly different from the reduced Struthio and Rhea which are closely related to one another by the presence of a rod‐like endonuclear perforatorium.
Microtubule diversity in ciliated cells: evidence for its generation by post‐translational modification in the axonemes of Paramecium and quail oviduct cells
Authors: Adoutte André , Delgado Pilar , Fleury Anne , Levilliers Nicolette , Lainé Marie‐Christine , Marty Marie‐Chantal , Boisvieux‐Ulrich Emmanuelle , Sandoz Daniel
Published: February 2003

Summary— The diversity of microtubular networks was analyzed in quail oviduct and in Paramecium cells using conventional and confocal immunofluorescence as well as pre‐ and post‐embedding EM immunocytochemistry with a variety of anti‐tubulin antibodies. The 6‐11B‐1 monoclonal antibody, specific for the post‐translational acetylation of Lys 40 of α‐tubulin [40], and a polyclonal antibody raised against Paramecium axonemal tubulin (anti‐PA tubulin antibody) [16] both decorated stable microtubular arrays in Paramecium ie ciliary axonemes and a set of microtubular bundles associated with the cortex, suggesting that the two antibodies may be directed against the same epitope. However, several differences in the immunocytological patterns yielded by each antibody on the two cell types were evident. For example, in quail, as in all other Metazoa, the anti‐PA tubulin antibody only decorated axonemes enclosed in normal ciliary membrane while it was unreactive on cytoplasmic tubulins. Immunoblotting of peptide maps of axonemal tubulins demonstrated that the epitopes of the two antibodies were indeed completely different. Double immunolabelling of dividing paramecia using a universal anti‐tubulin antibody and the anti‐PA tubulin one revealed that all newly assembled microtubular arrays were first detected by the universal antibody and, only shortly afterwards, by the anti‐PA tubulin one. This provided a strong indication that the anti‐PA tubulin antibody is directed against a post‐translational modification taking place on already assembled microtubules (MTs) (as previously known to be the case for acetylation and detyrosination). In taxol‐treated quail cells undergoing ciliogenesis, massive assembly of MTs and even axonemes occurred in the cytoplasm. These MTs were not decorated by the anti‐PA tubulin antibody however, suggesting that in Metazoa the post‐translational modification can only take place within the ciliary lumen. The present work provides one further mechanism for generating MT immunological and biochemical diversity post‐translationally; this may account for the high multiplicity of tubulin isoforms observed in ciliates which contain very little if any genetic diversity of tubulin genes.
‘Neurosecretion’ by synaptic terminals in the locust corpus cardiacum: is non‐synaptic exocytosis part of the regulated or the constitutive pathway?
Authors: Golding David W. , Pow David V.
Published: February 2003

Summry— Nerve fibres form conventional synaptic junctions with gland cells in the corpus cardiacum of the locust, Schistocerca gregaria. They contain synaptic vesicles whose contents are normally electron‐lucent, but which react positively to cytochemical tests for amines (eg, incubation in the false transmitter 5‐OHDA). Secretory granules are also present in the terminals and such inclusions are known to contain neuropeptides. The granules undergo non‐synaptic exocytosis and this process has been visualized by the application of tannic acid. Granule exocytosis gives clear signs of being part of a regulated secretory pathway: it is elevated in vivo by flight— a natural stimulus known to activate the gland (this effect is blocked by prior injection of trehalose); its incidence is closely correlated with a postsynaptic response, suggesting a role for the materials discharged in short‐term signalling; and when induced in vitro by high K+, it is Ca2+‐dependent. However, a low level of exocytosis was encountered under all conditions employed, suggesting the existence of a constitutive component. It is postulated that the regulated and constitutive patterns of discharge of neuropeptides are related to the roles of these materials as neurotrans/mittersmodulators and neurotrophic substances, respectively.
Liquid crystal‐type assembly of native cellulose‐glucuronoxylans extracted from plant cell wall
Authors: Reis Danièle , Vian Brigitte , Chanzy Henri , Roland Jean‐Claude
Published: February 2003

Summry— In numerous plant cell walls, the cellulose microfibrils are arranged in a helicoidal pattern which has been considered as an analog to a cholesteric order. Here, we report on the spontaneous helicoidal organization which occurs in acellular conditions from aqueous suspensions of cellulose. The cellulosic mucilage of mature seeds of quince (Cydonia oblonga L) was studied both in situ (pre‐release mucilage) and after water extraction and in in vitro re‐assembly (prolonged high speed ultracentrifugation, further progressive dehydration and embedding in LR White methacrylate or hydrosoluble melamine resin). The cellulosic component was characterized by the use of cellobiohydrolase (CBH1) bound to colloidal gold, and the glucuronic acid residues of the xylan matrix were characterized by the use of cationised gold. Inside the seeds, the pre‐release mucilage is mostly helicoidal, with the occurrence of more or less ordered domains, which indicate a fluid organization relevant to an actual liquid crystal state. Cytochemical tests revealed the tight association between cellulose and glucuronoxylans, the latter constituting a charged coat around each microfibril. Following the hydration of the seed, a cellulosic suspension was extracted in which microfibrils were totally dispersed. The progressive dehydration of the suspension gave rise to concentrated viscous drops. Ultrastructural observations revealed the occurrence of multidomain organization, from non‐ordered to cholesteric‐like regions, revealing that the mucilage is at the same time crystalline and liquid. This constitutes the first demonstration that liquid crystal type assemblies can arise from crystalline and biological cellulose in aqueous suspension. It strengthens the hypothesis that a transient liquid crystal state must occur during the cellulose ordering. The possible morphogenetic role of the glucuronoxylans in the cholesteric organization of the cellulose is discussed.
Effect of culture duration on hepatocyte subcellular membranes involved in endocytosis
Authors: Thirion Jacqueline , Wattiaux Robert
Published: February 2003

Summary— The influence of culture duration on some characteristics of hepatocyte subcellular membranes involved in endocytosis was investigated. Activity of enzymes located in plasma membrane, Golgi apparatus and lysosomes increases with time. These modifications are accompanied with several changes in sedimentation properties of these organelles. Endocytosis of [14C]sucrose and [14C]surcose‐LDL is not affected by culture age. On the contrary, [14C]sucrose‐ASF endocytosis strongly decreases in these conditions. These modifications are delayed to some extent by lowering the temperature. Addition to the culture medium of 3‐methyladenine (an inhibitor of autophagy), sodium butyrate, dimethylsulfoxide, phenobarbital or nicotanamide does not prevent the decrease of ASF endocytosis caused by culture duration. These results indicate that one must be cautions when extrapolating to liver in vitro, observations on endocytosis obtained with primary culture of hepatocytes.
The synthesis and accumulation of membrane protein 4.1 in Friend erythroleukemia cells
Authors: Benabdallah Khadija , Boivin Pierre , Dhermy Didier
Published: February 2003

Summary— The effect of extensive differentiation on the synthesis and accumulation of protein 4.1 were studied on Friend erythroleukemia grown in suspension and on fibronectin coated dishes. Whole membranes of Friend erythroleukemia cells (FELC) contained a protein 4.1a and 4.1b doublet of Mr 76 and 74 kDa and two minor bands of Mr 105 and 43 Da that cross‐reacted with anti‐human protein 4.1 IgG. These proteins were present even in uninduced cells. the synthesis of protein 4.1 was maximal after 4 days of induction in both suspension culture and in fibronectin‐coated dishes whereas the protein 4.1 continued to accumulate until the seventh day. More protein 4.1 accumulated in cells grown on fibronectin‐coated dishes, at each stage of differentiation, than in cells grown in suspension. The protein 4.1a/4.1b ratio changed during differentiation. The amounts of protein 4.1b increased progressively after induction until the protein 4.1a/4.1b ratio was similar to that of mouse mature erythrocyte. The protein 4.1a/4.1b ratio appears to be an internal marker of erythroid differentiation.
The evidence for Na+, K+‐ATPase activity in the epidermis of Pelobates syriacus tadpoles and toads
Authors: Rosenberg Mira , Warburg Michael R.
Published: February 2003

Summary— In the present study an attempt was made to localize cytochemically ATPase activity in the epidermis of Pelobates syriacus during its metamorphic cycle. In the epidermis of the legless tadpole, evidence for ATPase activity was confined intracellularly in two cell types: on the membranes of vesicles in the vesicle cells, and in the ER and Golgi inside the granular cell. This state continued throughout most of the tadpole life during the 2‐ and 4‐limbed stages. This is possibly an indication for either Ca2+ ‐ or Mg2+‐ATPases. Only in later stages, preceding metamorphic climax, did Na+‐K+‐ATPase activity shift to the baso‐lateral cell membranes bordering with the intercellular spaces. This continued after metamorphic climax in the juvenile toadlets, diminishing later in the adult stage.
Adhesion of sea‐urchin embryonic cells to substrata coated with cell adhesion molecules
Authors: Matranga Valeria , Di Ferro Daniela , Cervello Melchiorre , Zito Francesca , Nakano Eizo
Published: February 2003

Summary— A cell‐to‐substratum adhesion assay is developed to study the adhesion of sea‐urchin embryonic cells to coated substrata. The involvement in this process of both carbohydrate and protein molecules is reported. Concanavalin A (Con A) increases the attachment of cells to the substratum in a dose‐dependent manner and this effect is completely abolished when the incubation is carried out in the presence of the specific monocarbohydrate Con A‐inhibitor, α‐methyl‐d‐mannoside. A Con A‐mediated enhancement of cell‐to‐substratum adhesion was also detected on cells deprived of toposome, a glycoprotein complex responsible for cell‐to‐cell adhesion. The involvement of other molecules as well as toposome in the process of cell‐to‐substratum adhesion is also investigated. Results of these in vitro experiments indicate that all the molecules tested contribute to the process of cell‐to‐substratum adhesion.
The effect of clofibrate on amphibian hepatic peroxisomes
Authors: Ciolek Eric , Dauça Michel
Published: February 2003

Summary— Liver peroxisomes of two anuran amphibian species, Rana esculenta and Xenopus laevis, were studied in untreated and in clofibrate‐treated adults by means of complementary technical approaches, ie, ultrastructural cytochemistry, cell fractionation and marker enzyme activity assays. In untreated adults, hepatic peroxisomes were found to be very scarce in Xenopus when compared to Rana. Activities of catalase, d‐amino acid oxidase and of the three first enzymes of the peroxisomal β‐oxidation system were detected in the light mitochondrial fractions enriched in peroxisomes and prepared from livers of both species. Administration of clofibrate at a daily dose level of 60 mg (Rana) and 90 mg (Xenopus) during ten days induced a drastic peroxisome proliferation in Rana hepatocytes but had no visible effect on the hepatic peroxisomal population of Xenopus. The catalase activity and the peroxisomal β‐oxidation system of liver cells were enhanced in Rana as well as in Xenopus. The hepatic d‐amino acid oxidase specific activity was increased in Rana whereas it remained rather constant in Xenopus. Taking advantage of the behaviors of Rana and Xenopus hepatic peroxisomes, the molecular mechanisms of clofibrate induction are now investigated in the target liver cells of the two amphibian species.