bluuebunny/crossref_metadata_2025_split huggingface dataset:
Partial activation of surf clam oocytes by hypertonic treatment.
Authors: Coutu Louise , Larochelle Stéphane , Dubé François 
Published: October 2002

AbstractIn prophase I‐arrested surf clam oocytes, fertilization is the normal trigger for resumption of meiosis, first evidenced by germinal vesicle breakdown (GVBD). Various artificial agents are able to induce GVBD and most of them require the presence of external Ca2+ to be efficient. One exception to this rule is the reported possibility of inducing GVBD by an hypertonic treatment, using high concentrations of glycerol, in the complete absence of external Ca2+. We have investigated the processes underling glycerol‐induced activation and found that, under this condition, GVBD shows very slow kinetics and is not followed by any normal subsequent steps of meiosis, such as formation of metaphase chromosomes or polar body extrusion. Glycerol‐activated oocytes do not show the normal response in protein synthesis but they undergo increased protein phosphorylation which is inhibited by 6‐dimethylaminopurine (6‐DMAP), which also inhibits GVBD. We conclude that the hypertonic treatment by glycerol, in the complete absence of external Ca2+, induces a partial program of activation through increased protein phosphorylation but that the normal full response requires an increased Ca2+ influx as triggered by other well‐known artificial activating agents.
Modulation of glycolysis induction in primary cultures of rabbit kidney proximal tubule cells: the role of shaking, glucose and insulin.
Authors: Monteil Christelle , Leclere Caroline , Dantzer Françoise , Elkaz Veronika , Fillastre Jean‐Paul , Morin Jean‐Paul 
Published: October 2002

AbstractWe have assessed the impact of increasing oxygen availability on cellular phenotype expression of rabbit proximal tubule cells in primary culture developed with variable glucose and/or insulin contents. To mitigate hypoxia at the cell/medium interface, cells were shaken for the whole culture duration and their expressed phenotype was compared with those expressed by static cultures. O2 and CO2 tensions were kept constant in the incubator atmosphere. Glycolysis and gluconeogenesis pathways, detoxication system, and mitochondrial, apical and basolateral membrane marker enzyme activities were assessed. This study showed that the induction of glycolysis which appear in primary cultures of proximal tubule cells may be partially prevented by continuously shaking the cultures. This effect was more marked in the presence of glucose, suggesting better substrate oxidation in shaken cultures.
Immunodetection of spectrin antigens in plant cells
Authors: De Ruijter Norbert , Emons AnneMie 
Published: October 2002

AbstractThe occurrence of spectrin in plant cells was studied by immunoblotting of extracts, and its localization by immunolabelling of cells, using two polyclonal antibodies raised against spectrin from human and chicken erythrocytes. A variety of plant cells were studied. The two antibodies gave the same results on blots as well as on cells. Western blots of extracts showed weak immunolabelling at 220 kD, where spectrin can be expected, but bands at 85 kD stained more heavily. Because the latter bands were also seen on blots with commercially purified spectrin, we conclude that they were breakdown products of spectrin. Native plant extracts on blots from IEF gels showed a band at pI 4.8, where the purified animal spectrin is also found. Immunolocalizations done on whole cells, PEG‐, BMM‐, or cryo‐sections gave similar data. In most cells the labelling was localized predominantly at the plasma membrane, especially of thin‐walled cells. Labelling was also seen in the periphery of a particular class of organelles, probably plastids. This labelling was tissue specific in maize somatic embryos. During carrot somatic embryogenesis cytoplasmic labelling was observed depending on the developmental stage. Many cells with cytoplasmic labelling also had stained nuclei. Labelled nuclei had more condensed chromatin than non‐labelled nuclei.
The distribution of secretory products in plant cells is affected by brefeldin A
Authors: Satiat‐Jeunemaitre Béatrice , Hawes Chris 
Published: October 2002

SummaryThe patterns of redistribution of two classes of Golgi derived cell surface antigens recognised by monoclonal antibodies JIM1 and JIM7, after the treatment of roots with Brefeldin A (BFA) are described. The results for these secretory products are compared with those previously reported for Golgi membrane epitopes recognised by JIM 84. The preliminary results described here demonstrate that the combination of immunocytochemical techniques with drug induced perturbation of secretory pathways will be invaluable in enhancing our understanding of the pathways of intracellular trafficking in plants.
Spatial and temporal patterns of B hordein synthesis in developing barley (Hordeum vulgare L.) caryopses
Authors: Davies J. T. , Shewry P. R. , Harris N. 
Published: October 2002

AbstractmRNA species encoding B hordeins and B hordein protein have been localised in developing barley caryopses using in situ hybridisation and immunocytochemistry. B hordeins are first detected immunocytochemically in sections from 5 dpa (days post anthesis) barley caryopses. At this stage the endosperm is well differentiated and hordein levels are relatively constant across the starchy endosperm though notably absent from the aleurone layer. Analysis of serial transverse sections through later stages of caryopsis development (7‐10 dpa) show a distinct differential accumulation of B hordeins. Hordeins accumulate at the periphery of the starchy endosperm, towards the apex and along the endosperm/scutellum boundary. Using in situ hybridisation B hordein mRNA was detected in equivalent patterns to the protein indicating that there is regulation of gene product accumulation at a transcriptional level. 3‐D reconstruction of hordein in developing barley caryopses have been made using data from multiple serial sections in conjunction with a commercial computer‐aided design package.
Outer membrane protein gene expression traced by immunogold labelling in Rhizobium Leguminosarum bv. viciae strain 248 in Vicia sativa ssp. nigra.
Authors: Goosen‐de Roo Leentje , De Maagd Ruud A. , Lugtenberg Ben J. J. 
Published: October 2002

AbstractDuring differentiation from bacterium into nitrogen fixing bacteroid, the outer membrane protein RopA decreases in density. Comparison between size increase of the rhizobia and density decrease of a RopA protein epitope after immuno‐gold labelling, indicates that although ropA gene expression stops at the onset of nitrogen fixation, the amount of RopA protein probably remains the same.
Cytoskeleton‐bound polysomes in plants. III. Polysome‐cytoskeleton‐membrane interactions in corn endosperm.
Authors: Davies E. , Comer E. C. , Lionberger J. M. , Stankovic B. , Abe S. 
Published: October 2002

AbstractOver 80% of the polysomes in corn endosperm sediment along with protein bodies at 30 xg from seeds ground in cytoskeleton‐stabilizing buffer. The cytoskeleton‐disrupting agents, Tris‐HCl, K+, heparin, and sodium deoxycholate cause polysome release, while protease K and the non‐ionic detergent, PTE, are effective only in the presence of these agents, and RNase is almost without effect. We suggest that many of the polysomes in corn endosperm are associated via their ribosomes, but not mRNA or nascent polypeptides with the actin component of the cytoskeleton and only indirectly with membranes. Corn endosperm homogenates examined under the fluorescence microscope show polysomes coating individual protein bodies and co‐localizing with actin, but not with ER.
Phagocytic activity of Dictyostelium amoebae treated with an organochlorine pesticide.
Authors: Gayatri R. , Chatterjee S. 
Published: October 2002

AbstractThe effect of an organochlorine pesticide benzene hexachloride (containing α, β, γ and δ isomers) on the phagocytic activity of the vegetative cells of Dictyostelium discoideum was investigated. Benzene hexachloride (BHC) at concentrations of 60 ppm and above inhibited the phagocytic activity as revealed by 3H‐labelled E. coli uptake. The BHC treated cells also showed smaller and delayed plaque formation. Interactions of lipophilic pesticide with the hydrophobic cell surface presumably alters the receptor mediated phagocytosis of Dictyostelium amoebae.
The effect of differentiation inducers on the integrin expression of K562 erythroleukemia cells.
Authors: Järvinen Maarit , Ylänne Jari , Virtanen Ismo 
Published: October 2002

AbstractWe studied the effects of differentiation‐inducers on the integrin profile and adhesive properties of K562 leukemia cells. The fibronectin (Fn) receptor integrin, α5β1, was the only integrin expressed in suspension cultured K562 cells. When the cells were exposed to 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA) immunoreactivity for the β1 integrin subunit was slightly enhanced. TPA exposure also induced the appearance of the α2, α3, αv and β3 integrin subunits, but the platelet integrin subunit αIIb was not detected. On the other hand, hemin chloride‐induced erythroid differentiation of K562 cells diminished the expression of the α5β1 integrin on the surface of the cells. Adhesion experiments with TPA‐exposed K562 cells indicated that although the adherence to the extracellular matrix (ECM) proteins as a rule was low a few cells spread on these proteins. The present results specify the effects of differentiation inducers on the integrin profile of K562 cells and excludes the comprehension that TPA would induce expression of the platelet integrin αIIb on their surface. Our results also show, that an increased expression of a certain integrin does not necessarily lead to a comparable adhesion ability on its ligand in vitro.
Suppression of DNA synthesis and induction of apoptosis in rat prostrate by human seminal plasma inhibin (HSPI).
Authors: Mundle Suneel D. , Sheth Nandini A. 
Published: October 2002

AbstractIn vivo administration of HSPI (10.7 kDa FSH suppressing peptide of prostate) to intact adult male rats was found to suppress the basal levels of incorporation of 3H‐thymidine into DNA of ventral and dorsolateral lobes of the prostate, in a dose‐dependent manner. Interestingly, microscopic examination of the prostate histology of HSPI treated rats revealed a significantly increased incidence of apoptotic bodies which are indicative of cell death. In another experiment, HSPI was also found to suppress the active DNA synthesis in testosterone‐induced regrowth of prostate in castrated rats. Thus HSPI can suppress the basal and stimulated DNA synthesis and also induce apoptotic cell death in rat prostate.
Synergistic effect of interferon‐γ and phorbol myristate acetate on superoxide production by human monocytes.
Authors: Wolfson Marina , Nathan Ilana , Aharon Miriam , Dvilansky Alexander , Aboud Mordechai 
Published: October 2002

AbstractThis study demonstrates a synergistic effect of IFNγ and PMA on superoxide generation by human monocytes. A strict correlation was observed between the induction of superoxide production and PK‐C activation by PMA alone. No such correlation was evident for IFNγ. However, exposure of the cells to IFNγ for 10 to 15 hr prior to PMA treatment enhanced both superoxide production and PK‐C activation. Using protein kinase inhibitors, we noticed that while PMA exerted its effect by activating PK‐C, IFNγ operated via activation of calcium/calmodulin‐dependent or some other calcium‐dependent protein kinases. These kinases appeared to be involved in the effect of IFNγ on superoxide production, as well as in its potentiation of PMA activity.
In patients with common variable immunodeficiency, interleukin‐6 and expression of its receptor on B‐cells are normal
Authors: Junker U. , Heyden‐Rynsch B. v. d. , Dieher C. , Vogelsang H. , Jäger L. 
Published: October 2002

AbstractIn a group of patients suffering from common variable immunodeficiency (CVID), levels of interleukin‐6 (IL6) were measured and found to be in the normal range or even increased, for single patients. IL6 production of peripheral blood mononuclear cells was shown to be in the normal range when corrected for monocyte number. To exclude the possibility that the Interleukin‐6 receptor (IL6R) on B‐cells is missing, its expression was measured by assessing the binding of a Phycoerythrin‐derivative of IL6 by flow cytometry and correlated with various markers for B‐cells and T‐cells. As compared with normal controls, no statistically significant deviation of the group as a whole nor for individual patients could be shown. It was concluded that lack of B cell differentiation in the presence of normal to high IL6 as shown for these patients is not due to inability of the B cells to detect IL6 in the serum.
Role of stress fibers in the association of intermediate filaments with microtubules in fibroblast cells.
Authors: Roy Sujata Guha 
Published: October 2002

AbstractThe association between intermediate filaments (IF) and microtubules (MT) has been demonstrated by several experiments using MT inhibitors and by microinjecting specific antibodies. The actin cytoskeleton has recently been assigned a role in this process of drug induced IF collapse. However, this was not found to be true in large cells with irregular morphology. For instance, in early passage diploid fibroblasts of human origin and in armadillo cell lines, where the cells are large, irregular in shape and exhibit prominent stress fibers (SF), depolymerization of MT with nocodazole did not lead to collapse of IF. Instead, the IF formed bundles of coils that seemed to associate with the SF. Disintegration of the SF with cytochalasin B led to the collapse of the IF. It appears that the actin organization in such large cells with extensive SF, is not as contractile as in typical spindle shaped fibroblasts which have relatively less stable actin organization. The stable SF may actually prevent IF collapse.
Elemental mapping of fluorine using electron spectroscopic imaging for the intracellular localisation of an anthracycline drug (ME2303) in human ovarian cancer cells.
Authors: Huxham I. M. , Barlow A. L. , Mairs R. , Gaze M. N. , Workman P. 
Published: October 2002

AbstractA major limitation to the clinical usefulness of cancer chemotherapy is the onset of acquired drug resistance, in which the effectiveness of a drug such as Doxorubicin (DOX), used in a wide variety of neoplasms, diminishes following repeated administration. Resistance is associated with drug exclusion from tumour cell nuclei. New analogues of DOX have been synthesised to reduce patient cardiotoxicity and to increase anti‐tumour activity. More recently, a 2‐fluoroglycoside of DOX (ME2303) has been shown to be more resistant to glycolysis and has marked anti‐proliferative effects on DOX‐resistant tumours. The aim of the current study was therefore to determine the intracellular localisation of ME2303 in drug sensitive and resistant human ovarian cancer cell aggregates by mapping fluorine, as a means of understanding the complex mechanisms of drug resistance. Cell aggregates of the human ovarian cell line A2780 and its DOX‐resistant subline 2780AD were cultured for 1hr in 5μM of the drug ME2303, then chemically fixed and embedded in Lowicryl K4M using alcohol dehydration at −20°C. Ultrathin sections (40‐50nm) were examined on a Zeiss TEM 902 energy filtering electron microscope using 80Kv at a magnification of 12,000x. Fluorine maps were generated using the two window method by collecting two integrated images above and two integrated images below the K ionisation edge for fluorine (685eV) with a 15eV window. Image sequences were collected within 20sec to minimise the effects of mass loss from the specimen via a Dage SIT 66 video camera connected to a DT 2861 video interface board (512x512 pixels with 256 grey levels) within a 486 PC. In the A2780 cell line, fluorine was found to be distributed diffusely within the cytoplasm and at discrete sites within the nucleus. In contrast, fluorine in the 2780AD subline (co‐cultured with 1.4μM DOX to maintain resistance) was found to be largely associated with the peri‐nuclear Golgi region and with mitochondria, but was also found within cell nuclei, along the inner nuclear envelope and in the nucleolus. The intra‐nuclear localisation of fluorine suggests that even in the presence of DOX, ME2303 can mediate anti‐proliferative activity in DOX resistant human ovarian cancer cells by effective nuclear translocation.
Active ribosomal cistrons in plant nucleolus
Authors: Ghosh S. , Chakrabarti A. , Chaudhuri S. K. 
Published: October 2002

AbstractIn onion root‐tip cell nucleoli some tapered cylindrical structures appear in the dense fibrillar component (DFC) after cycloheximide treatment. These structures resemble the "Christmas‐tree" like configurations which have been noted in spread preparations from the nucleoli. The similarities in their general appearance are strengthened by observations after RNase and pepsin digestions. The presence of such structures in the DFC of prophase nucleoli has also been demonstrated. These observations indicate the presence of active ribosomal cistrons in DFC of the nucleolus. It is proposed that nucleolar transcription becomes initiated in the DFC around the FC (fibrillar centres) and then these transcripts along with their axis move to the granular component (GC) for their processing. As such some of these structures were observed to penetrate into the GC.
Changes in prometaphase chromosome motion are dependent on experimentally induced changes in kinetochore structure.
Authors: Geck David C. , Snyder Judith A. 
Published: October 2002

ABSTRACTPrometaphase PtK1 cells are treated with low concentrations of sucrose in order to analyze its effects on kinetochore structure, microtubule (MT) associations with the developing kinetochore and chromosome congression. Prometaphase cells treated with 0.15M sucrose slows chromosome congression, yet chromosomes form a metaphase configuration. However, 0.2M sucrose treatment prevents chromosome congression and affects some of the kinetochore MT linkages with the kinetochore, resulting in loss of chromosome congression. We use time lapse video microscopy and ultrastructural analysis to correlate changes in the linkages in the kinetochore MTs and the kinetochore to explain these findings. It appears hyperosmotic shock treatment can produce non‐functional linkages between kinetochore MTs and kinetochores such that chromosome congression is affected. When non‐functional linkages are formed, the presence of both a corona and matrix‐like material is also present, proximal to the kinetochore. The role of this material and its organization at the klnetochore is discussed in its relation to generating mitotic forces.
The effect of in vitro heating on the distribution of nuclear matrix polypeptides in HeLa cells
Authors: Martelli A. M. , Bareggi R. , Riederer B. M. , Marugg R. A. , Narducci P. 
Published: October 2002

ABSTRACTThe in situ nuclear matrix was obtained from HeLa cells. After permeabilization with nonionic detergent, the resulting structures were incubated for 1h at 37°C to determine whether or not such an incubation might result in the redistribution of nuclear polypetides which resisted extraction with buffers of high‐ionic strength (1.6 M NaCl or 0.25 M (NH4)2SO4 as well as DNase I digestion. Using indirect immunofluorescence experiments and monoclonal antibodies we show that heating to 37° C changes the distribution of a 160 kDa protein previously shown to be a component of the inner matrix network. On the other hand, a 125 kDa polypeptide was not affected at all by the incubation. Our results clearly indicate that the inclusion of a 37°C incubation (for example during digestion with DNase I) in the protocol to obtain the in situ nuclear matrix can result in the formation of in vitro artifacts.
Video enhanced laser scanning microscopic analysis of DNA comet formation.
Authors: Fairbairn Daryl W. , Rowe Kevin C. , O'Neill Kim L. 
Published: October 2002

ABSTRACTLaser Scanning Microscopy is a sensitive tool that provides a unique method of analyzing biological systems. Coupled with the Single Cell Gel assay, it allows for accurate and reproducible detection of DNA strand breaks. An understanding of the theory of DNA comet formation is lacking. Using dexamethasone induced apoptosis in murine thymocytes as a model for double strand breaks, we used video enhanced laser scanning microscopy to evaluate the leading edge of DNA migration in the single cell gel assay. In this system, comet length increases significantly within the first thirty seconds of electrophoresis, the greatest increase in length is completed within the first minute, and the first two minutes are important in significant increases in DNA migration during DNA comet formation.
ENDOCYTOSIS DURING POSTNATAL DIFFERENTIATION IN SUPERFICIAL CELLS OF THE MOUSE URINARY BLADDER EPITHELIUM
Authors: Romih Rok , Jezernik Kristijan 
Published: October 2002

ABSTRACTThis electron microscopical study was performed in order to follow the endocytic pathway of horseradish peroxidase and colloidal gold tracers and to determine the involvement of endocytosis in postnatal differentiation in superficial cells of the mouse urinary bladder epithelium. Morphometric analyses of late endosomes/multivesicular bodies from day of birth to day 25 were performed. The internalisation and intracellular transport of luminal plasmalemma to multivesicular bodies via endocytic vesicles, early endosomes and pleomorphic compartments was established. Dynamic changes in endocytic activity took place within the first few days of postnatal differentiation. During this period the number of multivesicular bodies changed in an inverse ratio to their size. After the third day endocytic activity gradually approached the low rate of adult urothelium.
EVALUATION OF FREQUENCY OF MICRONUCLEI IN EXFOLIATED CELLS FROM BLADDER OF MICE TREATED WITH BENZO(A)PYRENE, 2‐ACETYLAMINOFLUORENE AND CYCLOPHOSPHAMIDE
Authors: Konopacka Maria 
Published: October 2002

ABSTRACTThe micronucleus test (MNT) was applied in the epithelial cells from the bladder of mice treated with benzo(a)pyrene (BaP), 2‐acetylaminofluorene (2‐AAF) and cyclophosphamide (CP). Micronuclei (MN) were scored at different time on Feulgen and fast green stained smear preparations of exfoliated cells. These cells were obtained by scraping the internal surface of the bladder. The tested compounds gave the maximal response at 7‐10 days after treatment. The number of MN in epithelial cells was dose dependent. These results suggest that exfoliated bladder cells from mice can be used as indicators for genotoxic damage in proliferating cell populations.
Water channels in membranes
Authors: Benga Gheorghe 
Published: October 2002

ABSTRACTA systematic programme of comparative nuclear magnetic resonance measurements of the membrane permeability for water (Pd) and of activation energy (Ea,d) of this process in red blood cells of various wild, laboratory and domestic animals was carried out here. The RBC from humans, cow, sheep and kangaroos had Pd values around 5·10−3 cm/s at 25 °C, 7 · 10−3 cm/s at 37 °C with Ea,d values around 25 kJ/mol. For RBC from other ten marsupial species and from mouse, rat and rabbit, the Pd values were more than twice as high as for human RBC. For mosr RBC a high value of Pd was associated with a low value of Ea,d (range from 15 to 21 kJ/mol), pointing to specialized channels for water diffusion incorporated in membrane proteins. Recently a channel‐forming integral protein of 28 kDa (CHIP 28) was identified as a major water channel protein in the RBC membrane. A procedure for quantitating the purified CHIP 28 by densitometry of silver‐stained polyacrylmide gel electrophoreograms was developed. The analysis of a purified fraction of CHIP 28 showed that the 28 kDa component represents approximately two‐thirds of the sample with the remainder comprising the glycosylated high‐molecular‐weight component. A correlation between the content in CHIP 28 and the relative water permeability among RBC from different vertebrate species was attempted.