bluuebunny/crossref_metadata_2025 huggingface dataset:
Golgi complex and lysosomes in rabbit derived Pneumocystis carinii
Authors: Palluault François , Dei‐Cas Eduardo , Slomianny Christian , Soulez Benoît , Camus Daniel
Published: August 2004

Summary—

The ultrastructural morphology of Pneumocystis carinii obtained from nonimmunosuppressed rabbit is described in details. Golgi complex and primary lysosomes of P carinii are described here for the first time. They are easily revealed by the zinc iodide‐osmium tetroxide cytochemical reagent. Thiamine pyrophosphatase and β‐glycerophosphatase activities are found in the parasite but cytidine 5′ monophosphatase activity is not observed. A weak thiamine pyrophosphatase activity is detected in Golgi vesicles. An endomembranous saccular structure, present from the intracystic body stage to the precystic stage, apparently plays the role of secondary lysosome. A second type of endomembranous saccular structure, only present in the well developed trophozoitic and precystic forms is also described. The presence of carbohydrates in the cell wall of the parasite was demonstrated by periodic acid‐thiosemicarbazide‐silver proteinate staining and lectin concanavalin A labeling. The development of Golgi vesicles preceded the transition from double‐layered to three‐layered parasite stages.
Instability of pleomorphic tubulin paracrystals artificially induced by Vinca alkaloids in tissue‐cultured cells
Authors: Takanari Hideki , Yosida Toshimichi , Morita Joji , Izutsu Kosaku , Ito Tadahiro
Published: August 2004

Summary—

The processes of tubulin paracrystal induction in Chinese hamster ovary cells treated with a Vinca alkaloid, ie, vinblastine or vincristine, and treated simultaneously with one of the Vinca alkaloids and colcemid or colchicine were followed by four different microscopic techniques, in particular by tubulin‐immunofluorescence. Vinca alkaloid alone, in lower concentrations, induced basically tactoid or needle‐shaped (N‐shaped) paracrystals. However, the formation of crystalloid was greatly enhanced by increasing the concentration of Vinca alkaloid. Square or barrel‐shaped (S‐shaped) and hexagonal paracrystals were also commonly induced by simultaneous treatment with a Vinca alkaloid and colcemid or colchicine. Large rectangular paracrystals often displayed fibrillar or lamellar fine structures which ran perpendicular to the long axis but tended to cleave into fragments by spontaneous splitting. Electron micrographs revealed the fine structure of crystalloids to be aggregates of numerous filaments. The growth of paracrystals, particularly N‐shaped crystals, was markedly inhibited when cells were exposed to drug(s) at a low temperature (4°C). We confirmed that both N‐ and S‐shaped paracrystals dissociated rapidly after the culture medium was replaced with fresh, drug‐free medium. Glutaraldehyde‐fixed paracrystals treated with RNase solution were stained with acridine orange, showing a weak orange color. Possible factors involved in the assembly and disassembly of tubulin paracrystals are discussed.
Benzoxazinone kanamycin A conjugate. A new fluorescent probe suitable to detect mycoplasmas in cell culture
Authors: Monsigny Michel , Midoux Patrick , Depierreux Christiane , Bebear Christine , le Bris Marie‐Thérèse , Valeur Bernard
Published: August 2004

Summary— The synthesis of a new benzoxazinone derivative suitable to detect early infection of cultured cells with mycoplasmas is described. p‐[β—(7 — dimethylamino 1,4 — benzoxazin 2 — one 3yl) — vinyl] — phenylpropenoic acid was coupled to kanamycin A, an aminoglycoside leading to a cationic fluorescent probe which fluoresces at 600 nm upon excitation at 490 nm. This fluorescent probe is shown to heavily label the glycocallix of all the mycoplasma strains tested which are found to be associated with contaminated cultured cells and to allow an easy and rapid detection of contamination by fluorescence microscopy and flow cytometry.
Image analysis of the chromatin organization in the nuclear domains of freeze fractured hepatocytes and lymphocytes
Authors: Marinelli Fiorenzo , Falcieri Elisabetta , Squarzoni Stefano , Del Coco Rosalba , Zini Nicoletta , Manzoli Lucia , Maraldi Nadir Maris
Published: August 2004

Summary— The complex organization of the interphase nucleus can be analyzed, by way of thin sectioning and also freeze‐fracture. This approach has previously been utilized in association with image analysis to quantitatively describe the organization of isolated rat liver nuclei and nuclear matrices. The main nuclear domains which, in section, present marked differences due to their electron‐density, can be identified in replicas with more complex procedures, based on the quantitative evaluation of the number of particles per unit area and mainly by using image analysis. A quantitative analysis of the nuclear substructures has been performed by way of image analysis on in situ nuclei of freeze‐fractured cells presenting marked differences in the heterochromatin quantity, such as hepatocytes and lymphocytes. The replicated nuclear particles have been classified according to their diameter and the obtained histograms have been quantitatively evaluated. The nuclear domains, heterochromatin, interchromatin, nucleolus, present characteristic ratios among the three main classes of particles; that is, ribonucleoproteins, solenoid filaments and solenoid fibre aggregates. The typical patterns of the nuclear domains can be further stressed by selecting a single class of particles and by examining its topographic localization. While interchromatin and nucleolar domains present a similar quantitative pattern in hepatocytes and lymphocytes, the heterochromatin of lymphocytes contains a significative higher percentage of solenoid aggregates than that of hepatocytes.
Secondary ion mass spectrometry analysis of the copper distribution in Drosophila melanogaster chronically intoxicated with Bordeaux mixture
Authors: Marchal‐Ségault Danièle , Briançon Colette , Halpern Sylvain , Fragu Philippe , Laugé Ginette
Published: August 2004

Summary— The fungicides used intensively in agriculture may affect non‐target organisms. The concentrations of copper sulfate‐based fungicide, Bordeaux mixture, normally used in agriculture, can significantly reduce both the life span and breeding rate of Drosophila melanogaster. The present study examines the distribution of copper in organ sections of fruit flies intoxicated with Bordeaux mixture, by secondary ion mass spectrometry. The organs of most control flies contained no copper. In contrast, copper accumulated in the cytoplasm of all the mesenteron and Malpighian tubule epithelial cells of the treated flies. There were also copper deposits in the fat body and the epithelia of the seminal receptacle and accessory glands of some flies, but there was little or no copper in the ovaries. The mesenteron and Malpighian tubules are generally responsible for detoxification by accumulation of ingested metal salts in insects. The high concentration of Bordeaux mixture used saturated these organs and resulted in excess copper being deposited in other sites, such as the fat body and the reproductive system.
Association between microtubules and Golgi vesicles isolated from rat parotid glands
Authors: Coffe Gérard , Raymond Marie‐Noëlle
Published: August 2004

Summary— We report an isolation procedure of trans‐Golgi vesicles (GVs) from rat parotid glands. Various organelle markers were used, particularly galactosyl transferase as a trans‐Golgi marker, to test the purity of the GV fraction. A quantitative in vitro binding assay between microtubules and GVs is described. The vesicles were incubated with taxol‐induced microtubules, layered between 50% and 43% sucrose cushions and subjected to centrifugation. Unlike free microtubules which were sedimented, the GV‐bound microtubules co‐migrated upward with GVs. Quantification of these bound microtubules was carried out by densitometric scanning of Coomassie blue‐stained gels. The association between microtubules and GVs followed a saturation curve, with a plateau value of 20 μg of microtubule protein bound to 500 μg of GV fraction. The half‐saturation of the GV sites was obtained with a microtubule concentration of 20 μg/ml. Electron microscopy of negatively stained re‐floated material showed numerous microtubule‐vesicle complexes. Coating of microtubules with an excess of brain microtubule‐associated proteins (MAPs) abolished binding. In the absence of exogenous microtubules, we showed that the GV fraction was already interacting with a class of endogenous rat parotid microtubules. This class of colcemid and cold‐stable microtubules represents 10–20% of the total tubulin content of the parotid cell.
Mapping the cellular distribution of labelled molecules by SIMS microscopy
Authors: Hindie Elif , Coulomb Bernard , Beaupain René , Galle Pierre
Published: August 2004

Summary—

We took advantage of one of the main possibilities of ion microscopy, ie isotopic analysis, to study the cellular distribution of molecules labelled either with carbon 14 or with stable isotopes of low natural abundance such as nitrogen 15 and deuterium. The surface of the sample is bombarded with an ion beam (O2+, Cs+ etc). Secondary ions emitted from the sample are filtered by a mass spectrometer and the distribution of the labelling isotope is recorded. In this way, we obtained images showing the characteristic distribution of 14C‐thymidine and d‐arginine in human fibroblasts, and of 15N‐adenine in organotypic cultures of human breast cancer cells. The spatial resolution on the acquired images was close to 0.1 μm when using the UPS‐ONERA ion microprobe. The sensitivity of the method for detecting carbon 14 is far greater than that of autoradiography and the technique is both fast and quantitative. On the other hand, the capacity of ion microscopy for studying the tissular distribution of molecules labelled with stable isotopes, opens the way for biological and pharmacological tracer studies of human diseases.
The imaging and quantification of aluminium in the human brain using dynamic secondary ion mass spectrometry (SIMS)
Authors: Candy John M. , Oakley Arthur E. , Mountfort Simon A. , Taylor Geoffrey A. , Morris Christopher M. , Bishop Hugh E. , Edwardson James A.
Published: August 2004

Summary—

Dynamic secondary ion mass spectrometry (SIMS) has been utilised to study the post‐mortem distribution of aluminium in air‐dried frozen sections from unfixed, unstained human brain in order to minimise contamination of the tissue and avoid redistribution and extraction of endogenous tissue aluminium. Substrates, sputter‐coated with silver, were found to be free of focal aluminium surface contamination and thus minimised substrate induced artefacts in the tissue aluminium ion image. SIMS imaging of aluminium secondary ions at a mass resolution that eliminated the major molecular interferences, combined with a photomontage technique provided a unique strategy for studying aluminium distribution in tissue unrivalled by other spatially resolved microanalytical techniques such as laser microprobe mass spectrometry or X‐ray microanalysis. Using this strategy, high densities of focal aluminium accumulations have been demonstrated in the cerebral cortex of the majority of chronic renal dialysis patients studied. In contrast, such aluminium accumulations were absent in control patients. SIMS imaging of aluminium appeared to provide much better discrimination between the dialysis patient group and the control group than one of the most widely used techniques for measuring aluminium in bulk samples, graphite furnace atomic absorption spectrometry. Preliminary studies have shown the feasibility of quantifying focal aluminium SIMS images obtained from brain tissue using aluminium‐loaded brain homogenates as reference standards.
Calcium‐dependent self‐aggregation of toposome, a sea urchin embryo cell adhesion molecule
Authors: Cervello Melchiorre , Di Ferro Daniela , D'Amelio Lucia , Zito Francesca , Matranga Valeria
Published: August 2004

Summary— Sea urchin embryos can be easily dissociated into single cells by exposure to Ca2+‐ and Mg2+‐free seawater. When transferred back to normal seawater, isolated cells spontaneously form aggregates capable of development. Here, the Ca2+‐dependent self‐aggregation of toposome, a 22S glycoprotein complex which mediates cell‐cell adhesion in sea urchin embryos, has been investigated using the purified molecule. Results show that the 22S complex is completely converted to 15S particles by sedimentation on sucrose isokinetic gradients in the presence of EDTA. Reconstitution of the 22S complex is achieved by readdition of Ca2+. We propose that the 15S particle constitutes the toposome functional unit on the cell surface.
In vitro effect of fungal cyclodepsipeptides on leukemic cells: study of destruxins A, B and E
Authors: Odier Franc¸oise , Vey Alain , Bureau JP
Published: August 2004

Summary— The activities of three mycotoxins isolated from the hyphomycete Metarhizium anisopliae: destruxin A, B, and E (DA, DB and DE) are described and compared in vitro on leukemic cells. Their antitumor effect was investigated by flow cytometry on growth, cell viability and cell cycle perturbation 48 h after destruxin exposure. Against P388 leukemic cells, DE displayed greater antiproliferative activity than DA and DB. The minimum concentration required to inhibit 50% of cell proliferation is 0.33 μg/ml for DE, 11.7 μg/ml for DA and 9.4 μg/ml for DB. Cell cycle modifications were only observed with DE at 50 and 10 μg/ml and consisted in an accumulation of the cells in GO/1 phase. DA and DB did not modify the number of cells in G0/1 of the cell cycle. Nevertheless a decrease in the number of cells in G2 + M phase was induced by the three destruxins.
Effects of camptothecin, an inhibitor of DNA topoisomerase I on ribosomal gene structure and function in TG cells
Authors: Farabegoli Fulvia , Govoni Marzia , Novello Francesco
Published: August 2004

Summary— The effects of camptothecin treatment and topoisomerase I inhibition on ribosomal gene structure and function were investigated in TG cells, a human tumour cell line. 90‐ and 180‐min treatments with 25 μM camptothecin resulted in an increased DNA fragmentation and decreased activity of topoisomerase I in cell extracts. After 180‐min treatment, the incorporation of labelled uridine into total cell RNA was reduced to 39% and the ribosomal RNA synthesis to 10%, as compared to values of control cells. At the ultrastructural level, the nucleolar components appeared to be segregated; after selective DNA staining, with osmium‐amine complex, a part of the nucleolar chromatin of treated cells showed the presence of thin, extended DNA filaments, superimposable to those present in control cells.
Cellular analysis of the kinetics of alpha‐fetoprotein and nuclear oncogene activation in primary cultures of adult rat hepatocytes stimulated by epidermal growth factor
Authors: Tournier‐Thurneyssen Isabelle , Feldmann Gérard , Bernuau Dominique
Published: August 2004

Summary— Alpha‐fetoprotein (AFP), a fetal gene normally inactivated in quiescent adult hepatocytes, is re‐expressed in hepatocytes during the proliferating response induced by liver regeneration in vivo, or epidermal growth factor (EGF) in vitro. The nuclear oncogenes c‐jun, c‐fos and c‐myc are ‘immediate early’ genes also activated during the proliferative response of hepatocytes. Whether AFP gene activation is linked to oncogene activation is not known. As a first step in answering this question, we have analysed the cellular kinetics of nuclear oncogene and AFP gene activation in primary cultures of adult rat hepatocytes stimulated by EGF. Gene activation was evaluated at the mRNA level by dot blot and in situ hybridization, and at the protein level by immunoperoxidase. C‐jun, c‐fos and c‐myc mRNA steady state levels in total cellular RNA were increased from 30 min‐2 h after EGF stimulation. In situ hybridization analysis showed that transcripts of the three oncogenes increased in all hepatocytes after EGF stimulation. While unstimulated cultures did not immunostain for Fos and Myc proteins, Fos immunostaining was visible in the majority of hepatocyte nuclei I and 2 h after EGF addition, and Myc cytoplasmic immunostaining of the majority of hepatocytes was observed at 2 h of stimulation. AFP mRNA increased in total cellular RNA 2 and 4 h after EGF stimulation, with elevated in situ hybridization signal for AFP mRNA in all hepatocytes. No hepatocytes immunostained for AFP in unstimulated cultures, but a cytoplasmic labeling of 20–30% of the hepatocytes was observed 6 h after stimulation. These results indicate that sequential activation of nuclear oncogenes and of the AFP gene occurs in proliferating adult rat hepatocytes in culture. Activation of these genes results in a moderate increase of their expression in all hepatocytes.
The calcium loading of secretory granules. A possible key event in stimulus‐secretion coupling
Authors: Nicaise Ghislain , Maggio Katia , Thirion Sylvie , Horoyan Marianne , Keicher Erick
Published: August 2004

Summary—

The review focuses on calcium accumulation by secretory organelles. The observation that secretory granules contain variable and often important quantities of calcium (1–200 mM of total calcium) can be interpreted as a maturation index. A progressive loading with calcium would be permitted by a Ca2+‐transport mechanism on the granular membrane and calcium‐binding molecules in the granular core. The saturation of this store by the stimulus‐induced calcium transient would permit in mature (calciumloaded) granules the ionic crisis leading to exocytosis. The inside of secretory organelles being acidic, calcium influx into the granule can be driven by calcium‐proton exchange. The calcium‐proton exchanger could be a Ca2+‐ATPase.
Interaction of the Golgi membranes isolated from rabbit liver with microtubules in vitro
Authors: Murata Masayuki , Itoh Tomohiko J. , Kagiwada Satoshi , Hishida Ryuichi , Hotani Hirokazu , Ohnishi Shun‐Ichi
Published: August 2004

Summary—

We have developed a reconstituted model system to study the interaction of the Golgi membranes isolated from rabbit liver with taxol‐stabilized bovine‐brain microtubules without microtubule‐associated proteins (MAPs). The Golgi membranes are associated with microtubules. The sheets of vesicles and the membranous tubules are observed along microtubules by direct visualization using differential‐interference‐contrast, dark field, or fluorescence microscopy. The monoclonal antibody against Golgi membranes suggests that the Golgi membranes, but not the contaminating vesicles, are interacting with microtubules. The degree of association is assayed quantitatively using rhodamine‐labeled microtubules after separation of the complex from unbound microtubules by centrifugation upon sucrose gradient. The association is inhibited by crude MAPs, purified MAP2, or 1.0 mM ATP. However, the association neither requires the cytosol from rat liver or bovine brain nor N‐ethylmaleimide, brefeldin A, or GTP‐γ‐S. The association is mediated by trypsin‐sensitive peripheral protein(s) on the Golgi membranes.
A predominant basic α‐tubulin isoform present in prophase Xenopus oocyte decreases during meiotic maturation
Authors: Thibier Catherine , Denoulet Philippe , Jessus Catherine , Ozon René
Published: August 2004

Summary— Xenopus oocytes are blocked in prophase of the first meiotic division. During the G2/M transition drastic changes occur both in the cytoskeletal organization and in the capacity of tubulin to polymerize. Posttranslational modification of tubulin isoforms might be one of the factors that control the dynamic properties of microtubules. We have therefore analysed, by two‐dimensional polyacrylamide gel electrophoresis, the isotubulins purified from Xenopus oocytes, and we show that tubulin is resolved into at least four α‐isoforms and four β‐isoforms. We have identified a basic α (αb)‐tubulin isoform which is specific to prophase arrested oocyte and that progressively disappears during meiotic maturation; its decrease is initiated when the nuclear envelope breaks down and is controlled by the nucleus. Using 35S methionine labelled oocytes we demonstrate that the disappearance of the αb isotubulin results from both an arrest of its biosynthesis after maturation, and from posttranslational modification which induces a shift of this α‐isoform to a more acidic pI. Moreover, in vitro experiments using 35S prelabelled tubulin purified from prophase oocytes show that metaphase extracts containing MPF activity are able to induce the acidification of the αb‐isoform, suggesting that the observed post‐translational modification might be regulated by p34cdc2. However, the nature of this modification remains to be elucidated.
Spatial distribution of the Sm antigen in Drosophila early embryos
Authors: Ségalat L , Lepesant JA
Published: August 2004

Summary— Anti‐Sm antibodies recognize the major small nuclear RNA‐protein particles (snRNPs) involved in pre‐mRNA processing. The spatial distribution of the snRNPs has been investigated in Drosophila embryos up to the cellularization stage (cycle 14), using the Y12 anti‐Sm antibody. Our results show that: 1) all or most of the Sm antigen is localized in the cytoplasm of the syncitial blastoderm until the 12th cycle of division, in both the nuclear and cytoplasmic compartments at cycle 13, and then in the nuclei at cycle 14 and later. This relocalization takes place when zygotic transcriptional activation occurs; 2) at the subcellular level, the Sm antigen localizes in a speckled pattern and in foci‐like structures within the nucleus of Drosophila blastoderm embryos; 3) strikingly, some nuclei of embryos at the 14th cycle appear to contain more snRNPs than others. The position of these nuclei differs from one embryo to another, and their distribution does not resemble any known developmental pattern of Drosophila embryogenesis. We propose that random differences in snRNP concentration may serve as an epigenetic signal for stochastic events occurring during development.
Stress response in Drosophila subobscura: DNA‐RNA hybrids and transcriptional activity
Authors: Arbona Maria , Cuenca Juan Bautista , De Frutos Rosa
Published: August 2004

Summary— Immunofluorescent techniques have been used in the analysis of DNA‐RNA hybrids occurrence and its relationship to transcriptional events on polytene chromosomes of Drosophila subobscura. We have studied the distribution of these hybrids on uninduced/induced chromosomes. Two different indirect immunofluorescence methods for the detection of DNA‐RNA hybrids were used. Our data confirm the positive correlation between localization of DNA‐RNA hybrids and transcriptional activity by following the Büsen et al procedure 1982. Using the other protocol, which allows chromosomal DNA‐RNA to denature and renature, makes DNA‐RNA hybrids detectable not exclusively in active chromosomal regions. Taking Büsen as method of choice, this technique allowed to localize the exact transcriptional active sites on puffs: hybrid fluorescence was restricted to marginal or central puff areas. Moreover, no correlation between fluorescence and puffs size was found. However, our studies on induced chromosomes indicate that: 1) the 15DE puff, previously described as t‐puff, was not really a heat shock puff, since no transcriptional activity was detected; 2) hybrid fluorescence at 2C and 31CD regions was observed. No labelling was found in these loci in the autoradiography data, reported by other authors.
Clinical applications of flow cytometry in hematology and immunology
Authors: Drouet Mireille , Lees Olivier
Published: August 2004

Summary— Rapid developments in computer technology combined with new fluorescent dyes and monoclonal antibody production have led to the development of a powerful tool: flow cytometry. The techniques of flow cytometry can be applied in a wide clinical field, from routine tasks to research in immunology and hematology. The availability of automated instruments and standardized sample preparation methods have led to its daily clinical use, helping diagnosis, prognosis or monitoring therapy. Further advances will be made with the introduction of multi‐parametric analysis ie quantification of antigen expression of cell surface antigens.
Interlaboratory quality assessment of lymphocyte phenotyping. Etalonorme 1990–1992 surveys
Authors: Goguel AF , Crainic K. , Ducailar A. , Ouin M.
Published: August 2004

Summary— A 3‐year interlaboratory proficiency testing for lymphocyte subset phenotyping was initiated as part of the Etalonorme national quality control program. Specimens consisted of fresh whole blood and of lyophilised mononuclear cells (Cytotrol Coulter). The number of participating laboratories was 62 in 1990, 99 in 1991 and 129 in 1992. Statistical analysis indicated that results of phenotyping, expressed as percentages of positive cells, are not related to reagents, instruments or differences in methodology (like, eg time and temperature of incubation). The highest dispersion was observed for total lymphocyte counts and was found to correlate with the type of calibration of the instrument. The coefficients of variation for different lymphocyte subsets were similar if phenotyping was performed on whole blood or lyophilised cells and varied inversely with the percentage of positive cells in each specimen. The consistency of the results indicated that they could serve as a basis for clinical decisions.
Image and flow cytometry: Companion techniques for adherent and non‐adherent cell analysis and sorting
Authors: Métézeau Philippe
Published: August 2004

Summary— Flow cytometry (FMC) is an analytical and preparative technique whereas image analysis is only applied to cell analysis. Recently, image analysis has been adapted as a preparative method using a new technique: image cytometry for analysis and sorting (ICAS). FCM and ICAS are complementary. Flow cytometry allows rapid, quantitative and precise study of fluorescence and light scattering in a large number of cells in suspension, while ICAS analyses fewer cells (adherent cells or tissue) on the basis of fluorescence, morphology and size. ICAS can use these criteria to destroy unwanted cells and hence sort selected cells. ICAS can also be used for confocal microscopy and laser surgery.
Role of calcium during release of mollusc oocytes from their blocks in meiotic prophase and metaphase
Authors: Abdelmajid H. , Guerrier P. , Colas P. , Durocher Y. , Gobet I. , Krantic S. , Leclerc‐David C. , Moreau M. , Néant I. , Rivailler P. , Tomkowiak M.
Published: August 2004

Summary— Bivalve oocytes constitute an excellent model to study the mechanisms which control cell division, since they arrest at different stages of the meiotic process and respond quite synchronously to various external signals regulating their evolution. Different situations were observed, according to the species, which required a more careful analysis. For example, the same serotonin (5‐HT) signal was found to drive prophase‐arrested oocytes of Spisula to the female pronucleus stage, whereas Ruditapes oocytes stopped in metaphase I. In this last species, 5‐HT treatment thus represents a necessary prerequisite for further development since sperm cannot penetrate prophase‐arrested oocytes, in contrast to the situation found in Spisula. The reasons for these differences cannot be found at the level of the receptors and second messengers. In both species, we found that Ca2+ was involved as a second messenger and required to release oocytes from their blocks in prophase and metaphase I. This is an unexpected and puzzling situation since MPF is activated by the prophase Ca2+ surge and inactivated during metaphase‐anaphase transition. The mechanisms underlying these paradoxical situations are discussed, taking into account results from previous observations and experiments. Briefly, our data suggest: I) that the absence of K− sensitive voltage‐gated Ca2+ channels may be responsible for the unfertilizability of prophasearrested Ruditapes oocytes; and ii) that functional variations in the network of activated kinases present in prophase and metaphase oocytes may be responsible for the divergent responses exhibited by Spisula and Ruditapes oocytes. In particular, these oocytes differ in their sensitivity to Ca2+/calmodulin antagonists and in tyrosine phosphorylation of their activated p34cdc2 kinase.
Immunolabelling of the presynaptic membrane of Torpedo electric organ nerve terminals with an antiserum towards the acetylcholine releasing protein mediatophore
Authors: Brochier Guy , Israel Maurice , Lesbats Bernard
Published: August 2004

Summary—

Mediatophore is a nerve terminal membrane protein purified from Torpedo electric organ on its ability to translocate acetylcholine upon calcium action. An antiserum able to immunoprecipitate mediatophore activity was used to study the subcellular distribution of this protein. The presynaptic membrane exhibited a strong and discontinuous immunogold labelling, especially at the active zone where ACh is thought to be released. Two antigens were recognized on immunoblots of synaptosomal membranes: the 15‐kDa subunit of mediatophore and a 14‐kDa membrane protein that has a wide non‐neuronal distribution. Antibodies purified from the serum on native mediatophore and monospecific towards the 15‐kDa antigen still gave a high presynaptic membrane localized labelling. In addition, a few 14‐kDa protein sites were present at the active zone. The Schwann cell finger interposed between the presynaptic membrane and the postsynaptic arch also exhibited the 14‐kDa antigen raising the question of a possible interaction of mediatophore with the 14‐kDa protein originating from the Schwann cell.
Structural analysis of glycosyl‐phosphatidylinositol membrane anchor of the Toxoplasma gondii tachyzoite surface glycoprotein gp23
Authors: Tomavo Stanislas , Dubremetz Jean‐Francois , Schwarz Ralph T.
Published: August 2004

Summary—

In this study we describe the biochemical features of the Toxoplasma gondii tachyzoite surface glycoprotein, gp23, demonstrating that it is attached to the parasite membrane by a glycosyl‐phosphatidyl inositol anchor. Gp23 was metabolically labeled with tritiated palmitate, myristate, ethanolamine, inositol, glucosamine, mannose and galactose, as expected for a GPI‐anchor structure. Gp23 was released from the surface of living parasites after treatment with phosphatidyl inositol‐specific phospholipase C (PI‐PLC) and the resulting water‐soluble protein was immunoprecipitated with a monoclonal antibody specific for gp23. The GPIcore glycan was generated after aqueous‐HF dephosphorylation followed by nitrous acid deamination and its carbohydrate structure was analyzed using selective exo‐ and endoglycosidase treatments. Finally, the phosphatidylinositol moiety of gp23 was characterized using PI‐PLC and phospholipase A2 (PLA2) digestions. Our cumulative data suggest that gp23 of T gondii tachyzoites contains a modified GPI‐backbone similar to the mammalian Thy‐1 anchor, consisting of a conserved core structure (ethanolaminePO4‐6‐Manαl‐2‐Manαl‐6‐Manαl‐4‐GIcNαl‐6‐PI) bearing β‐linked N‐acetylgalactosamine residue(s).
Localization of a Band 3‐related protein in the mitochondria‐rich cells of amphibian skin epithelium
Authors: Devuyst Olivier , Rott Ruti , Denef Jean‐François , Crabbé Jean , Katz Uri
Published: August 2004

Summary—

Based on immunoblotting procedure, the isolated epithelium of amphibian skin was found to contain a 180 kDa protein which cross‐reacts with a polyclonal antiserum raised against human erythrocyte Band 3. Immunoperoxidase and immunofluorescence staining techniques indicated that the Band 3‐related protein was localized in the mitochondria‐rich cells (MRC) of this epithelium, with characteristic apical labelling pattern. Our findings show that the putative apical anion exchanger of the MRC is immunologically related to the band 3 multigenic family, which catalyzes Cl‐HCO3
− transmembranous exchange. It thus suggests a molecular basis for the role played by these cells in the transepithelial Cl pathway and acid‐base regulation.
Spies, files and lies: explaining the failure of access to Securitate files
Authors: Stan Lavinia
Published: August 2004

Transitional justice in post-communist Romania has made little progress since the Council for the Study of Securitate Archives was set up in early 2000. This article discusses several factors that might explain the failure of giving citizens access to the files compiled by the communist-era secret political police and of publicly identifying the former political police agents and informers.
Neuropsychologische Grundlagenforschung bei demenziellen Erkrankungen anhand ausgewählter Beispiele
Authors: Gauggel Siegfried , Böcker Maren
Published: August 2004

Zusammenfassung: Demenzielle Erkrankungen verursachen einen kontinuierlichen Abbau kognitiver, emotionaler und motivationaler Funktionen und Prozesse. Der Verlauf, der Umfang und die Art dieses kognitiven Abbaus ist bei den verschiedenen Demenzformen unterschiedlich und kann mit neuropsychologischen Untersuchungsverfahren sehr genau dokumentiert und beschrieben werden. Aber nicht nur für klinische Zwecke sind neuropsychologische Untersuchungsbefunde wichtig, sondern auch für die Entwicklung fundierter Modelle über die Funktionsweise des gesunden Gehirns. In diesem Beitrag werden der neuropsychologische Forschungsansatz sowie ausgewählte Ergebnisse neuropsychologischer Forschung mit Demenz-Patienten skizziert. Insbesondere werden überblicksartig neuropsychologische Studien zur kognitiven Reservekapazität, zum semantischen Gedächtnis und zur Motivation vorgestellt.
Memory Span in German and Chinese: Evidence for the Phonological Loop
Authors: Lüer Gerd , Becker Dietrich , Lass Uta , Yunqiu Fang , Guopeng Chen , Zhongming Wang
Published: August 2004

Three experiments are conducted with German and Chinese student subjects to investigate short-term memory performance with regard to different kinds of stimulus material. Experiment 1 demonstrates that the Chinese subjects’ superior memory span performance cannot be traced back to existing differences in intelligence (assessed with Raven’s Advanced Progressive Matrices Test). In Experiment 2 a high correlation is found between the oral reproduction time of test items in the two languages and the resulting memory span of subjects. The results of Experiment 3 show that the Chinese subjects’ superiority in performance decreases and disappears completely where it is difficult to find verbal descriptions for the items to be memorized. These findings are discussed within the framework of Baddeley’s (1990) working memory model and cross-cultural intelligence research.
Five Big, Big Five Issues
Authors: De Raad Boele
Published: August 2004

This article discusses the rationale, content, structure, status, and cross-cultural assessment of the Big Five trait factors, focusing on topics of dispute and misunderstanding. Taxonomic restrictions of the original Big Five forerunner, the “Norman Five,” are discussed, and criticisms regarding the lexical hypothesis are refuted. The main issue of the psycholexical approach, namely, coverage of the trait domain, is elaborated upon, and the logic of the circumplexical structuring of the trait variables is summarized. A distinction is made between the common status of the Big Five approach, with a description of the competing positions of the Big Five model and other personality models, and the particular status of the Big Five approach, including its role as a general communication medium of personality traits. Finally, a review of recent, psychometrically based comparisons among different taxonomies is provided, lending support to the Big Five model as the main working hypothesis, on the one hand, but also showing discrepancies between languages, particularly as regards Factor V.
Microbreaking and the enhancement of air‐water transfer velocity
Authors: Zappa C. J. , Asher W. E. , Jessup A. T. , Klinke J. , Long S. R.
Published: August 2004

The role of microscale wave breaking in controlling the air‐water transfer of heat and gas is investigated in a laboratory wind‐wave tank. The local heat transfer velocity, kH, is measured using an active infrared technique and the tank‐averaged gas transfer velocity, kG, is measured using conservative mass balances. Simultaneous, colocated infrared and wave slope imagery show that wave‐related areas of thermal boundary layer disruption and renewal are the turbulent wakes of microscale breaking waves, or microbreakers. The fractional area coverage of microbreakers, AB, is found to be 0.1–0.4 in the wind speed range 4.2–9.3 m s−1 for cleaned and surfactant‐influenced surfaces, and kH and kG are correlated with AB. The correlation of kH with AB is independent of fetch and the presence of surfactants, while that for kG with AB depends on surfactants. Additionally, AB is correlated with the mean square wave slope, 〈S2〉, which has shown promise as a correlate for kG in previous studies. The ratio of kH measured inside and outside the microbreaker wakes is 3.4, demonstrating that at these wind speeds, up to 75% of the transfer is the direct result of microbreaking. These results provide quantitative evidence that microbreaking is the dominant mechanism contributing to air‐water heat and gas transfer at low to moderate wind speeds.
Dissipation of isotropic turbulence and length‐scale measurements through the wave roller in laboratory spilling waves
Authors: Govender K. , Mocke G. P. , Alport M. J.
Published: August 2004

The measurement of turbulence dissipation rates and length scales associated with three‐dimensional isotropic structures under spilling waves breaking in a laboratory surf zone is presented. Dissipation rates were estimated from the spectral characteristics of the turbulence velocities in the inertial subrange, and length scales were estimated using measurements of the turbulent kinetic energy and dissipation rate. The spatial velocity flow fields for the above analysis were measured using digital correlation image velocimetry. A unique set of measurements that spans the entire water column, including the aerated portion near the crest of the wave, is presented. Dissipation rates were found to reach a maximum above the effective trough level, with over 80% of the depth integrated dissipation occurring in this upper zone. The total depth integrated turbulence dissipation rate is found to be up to an order of magnitude smaller than the local rate of wave energy dissipation due to breaking, the primary turbulence production source. The length scale is found to increase in magnitude below the surface, consistent with the idea that turbulence production occurs above the trough level in the vicinity of the wave roller and is transported downward toward the bed.
Magnetic dipole anomalies as indicators of mantle wedge serpentinization
Authors: Kido Yukari , Kido Motoyuki , Fujioka Kantaro
Published: August 2004

Fine‐scale magnetic anomaly data based on high‐density airborne surveys have revealed several dipole anomalies along the Chichibu Zone (CZ), which lies parallel to the Nankai Trough and forms a part of the accretionary complex of southwest Japan. A plausible explanation of magnetic sources for the anomalies is a series of fossil serpentine diapirs involved during the accretion process. Serpentine diapirs are known to be developed in several forearc regions as mantle wedge serpentinized material associated with dehydration of the subducting oceanic slab. Surface geological and paleomagnetic evidence also suggests the existence of serpentine bodies in the CZ. We applied a magnetic inversion to each of the dipole anomalies and determined the magnetic bodies in a triaxial ellipsoid approximation. Magnetic bodies are interpreted to lie nearly parallel to the CZ and are inclined southward. Intensities of magnetization are compatible with those expected by measured susceptibilities of samples in the subareal CZ, and their directions are roughly the same as the current geomagnetic field, implying that the induced magnetization is dominant rather than the remanent component.
Secular variation of the Late Archean–Early Proterozoic geodynamo
Authors: Smirnov A. V. , Tarduno J. A.
Published: August 2004

We report new paleomagnetic data from ∼2.5 Ga dikes of the Superior Province and derive estimates of paleosecular variation. When combined with data from coeval dikes of the Karelia Craton (Russia) and older (∼2.7 Ga) volcanics of the Pilbara Craton, these estimates suggest a latitudinal variation of secular variation similar to that of the last 5 million years, but with potentially smaller quadrupole family contributions. The observations are consistent with some numerical models of the field that suggest a more dipolar field when the Earth had a much smaller solid inner core.
A Generalized Significance Testing Method for Global Measures of Spatial Association: An Extension of the Mantel Test
Authors: Lee Sang-Il
Published: August 2004

This research is concerned with providing a generalized significance testing method for global measures of spatial association by extending the Mantel test. Even though it has long been recognized that univariate spatial association measures such as Moran's I and Geary's c are special cases of Mantel's generalized association statistic, an intensive and comprehensive examination of the connections, particularly in terms of significance testing has never been undertaken. Furthermore, researchers have faced difficulties in dealing with spatial weights matrices with nonzero diagonal elements, and establishing the significance testing method for bivariate spatial association measures such as Cross–Moran and Lee's L. The author demonstrates that the proposed extended Mantel test can be applied to any global measure of spatial association with any form of spatial weights matrix in order to approximate the first two moments of the measures. A Monte Carlo simulation for each measure with various forms of spatial weights matrices confirms the exactness of the approximation.
The Changing Dynamics of Land-Use Change in Rural China: A Case Study of Yuhang, Zhejiang Province
Authors: Xu Wei
Published: August 2004

There is considerable debate in the literature on the extent and magnitude of Chinese rural land-use change since the onset of reforms in 1978. Moreover, there is little agreement on the factors leading to rural land-use change. Urbanization of the countryside, rural industrialization and housing development, lack of systematic agricultural protection policies and mechanisms for their implementation, and land-development programs are often considered responsible for the conversion of agricultural land to nonagricultural uses. Through a detailed case study of Yuhang in Zhejiang Province, the author attempts to unveil the complexity involved in land-use change in rural China. A variety of data sources, including published and unpublished official documents and statistics, local gazetteers, key informant interviews, and field observations, are employed. The results of the case study indicate a substantial reduction in agricultural land over the last twenty years. However, the path of this decline has not been smooth. The second decade of reform saw much evidence of decline in agricultural land. Spatially, the most severe decrease in agricultural land has been in areas close to urban centers, and with high accessibility. Urban sprawl, rural industrialization, and housing development have all contributed to the loss of agricultural land. But the author concludes that governments at various levels have played contradictory roles in the process of change. Whereas the governments have made a series of policy initiatives to protect agricultural land, they have, however, been the most important players in destabliizing the land base for agricultural production.
Migration, Care, and the Linked Lives of Dual-Earner Households
Authors: Bailey Adrian J , Blake Megan K , Cooke Thomas J
Published: August 2004

In this paper we explore how family relations influence the migration decisions of partners in dual-earner households. Specifically, we focus on how care responsibilities link the lives of partners, their children, and their parents, and how these ‘linked lives’ enable and constrain migration. We adopt a grounded theory approach and interview partners in two suburbs of Boston, Massachusetts. The results have two implications for the development of family migration theory. First, as dual-earner households make family migration decisions in the context of linked lives, these migration decisions cannot be understood as either economically driven or care driven, being contextualised by both spheres. Second, the importance of intergenerational links may increase the incidence of return migration of later-life dual-earner households.
The Internationalisation/Globalisation of Retailing: Towards an Economic – Geographical Research Agenda
Authors: Coe Neil M
Published: August 2004

Within economic geography, the internationalisation of retailing is a much understudied element of contemporary globalisation processes. In this paper the author seeks to develop the research agenda in this area from an economic – geographical perspective that is sensitive to spatial and temporal fluctuations in corporate strategies and investment patterns, the importance of political economic context(s), and the variety of potential developmental outcomes. The paper is structured into two main parts. First, the author offers a review of current levels of retail internationalisation in static and dynamic terms, illustrating that this is a phenomenon that demands more academic attention. The second reveals several limitations in the prevailing management/business approach to the topic, and maps out an explicitly geographical research agenda on the internationalisation of retailing. Six key areas in which research can usefully proceed are identified.
Designing and Living in a New Industrial Suburb: Experiences in the Cannock Chase Coalfield from the 1950s to the 1970s
Authors: Evans Gareth , Larkham Peter J
Published: August 2004

The immediate postwar period was one of major change in UK industry and society. The restructuring of the coal industry involved large-scale population movement from declining areas to more productive areas including Cannock Chase. New housing estates were constructed to house these migrants. In this paper we review aspects of the location and design of these estates, and discuss a long-term study of the experiences of miners and their families in a new physical and cultural context. The long distance of their move led to cultural isolation, which was reinforced by the location and design of the estates. The lack of estate facilities persisted for years after their construction. Several of the estates are now problem estates requiring massive investment. But the cohesion of the mining community distinguishes these estates from other studies of migration to new suburban estates.