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  • 1
    Electronic Resource
    Electronic Resource
    Comparative studies on the histology of the ovotestis in Hypselodoris tricolor and Godiva banyulensis (Gastropoda, Opisthobranchia), with special reference to yolk formation (1986)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 188 (1986), S. 105-118 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The histology of the ovotestis was studied by light and electron microscopy in two nudibranch gastropod species. While in Hypselodoris tricolor the ovotestis is intimately associated with the digestive gland tissue, the large gonadal mass of Godiva banyulensis is placed freely in the haemocoele. This fact results in great histological differences between both species.As is common among Mollusca, the immature yolk granule in Hypselodoris and Godiva presumably originates from membrane-rich cytoplasmic inclusions, which we have termed dense multivesicular bodies. Such inclusions consist of an outer membrane enclosing membrane remnants and a granular, electron-dense material. These elements are accumulated and mixed in the center of the dense multivesicular body and could be actually transformed into the paracrystalline core of the immature yolk granule, the cortex of which is made up of part of the central accumulation materials that have not spread into the crystal. During vitellogenesis, some mitochondria are subjected to a process of transformation affecting mainly their inner membrane (including mitochondrial cristae) and matrix. However, the conversion of modified mitochondria into yolk precursors, as reported for other gastropod species, could not be determined with absolute certainty on the basis of our observations on static material.The mature yolk granule consists of a central paracrystalline core, similar in structure to that of the immature yolk granule, and a peripheral membranous cortex, which seems to spread centripetally, thus permitting the crystal to grow. The cortical material consumed in synthesizing the central core appears to be restored by addition of degenerative mitochondria to the yolk granule surface.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051880110
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  • 2
    Electronic Resource
    Electronic Resource
    F-actin in guinea pig spermatozoa: Its role in calmodulin translocation during acrosome reaction (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 33 (1992), S. 172-181 
    Details
    ISSN: 1040-452X
    Keywords: F-actin in guinea pig spermatozoa ; Calmodulin ; Cytochalasin D ; Phalloidin-rhodamine ; Acrosomal reaction ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The presence of actin has been determined in mammalian spermatozoa. However, its function in these cells is still almost unknown. Only in boar spermatozoa has evidence for F-actin and a possible function for it been presented. In this work, actin distribution and F-actin were determined in uncapacitated, capacitated, and acrosomal-reacted guinea pig spermatozoa, by means of monoclonal and polyclonal antibodies, using an indirect immunoperoxidase technique, and by the use of rhodamine-phalloidin. With the last probe we found filamentous actin in these cells. By both techniques, actin was detected in the acrosome and in the entire tail. In some cells with acrosomal reaction, actin was also detected in the equatorial and in the postacrosomal regions. SDS-PAGE and Western blots immunostained with monoclonal and polyclonal anti-actin antibodies confirmed the presence of actin in extracts of guinea pig spermatozoa. Actin was also detected in preparations of Percoll-purified spermatozoa. We have communicated that guinea pig spermatozoa show a change on calmodulin location during the acrosome reaction. They present it first in the equatorial region and later in the postacrosomal region. To determine if F-actin participates in this calmodulin translocation, we studied the effect of cytochalasin D. It was found that the number of cells with calmodulin in the equatorial region increased in the presence of cytochalasin D while the number of cells with calmodulin in the postacrosomal region decreased. We also found that after cytochalasin D treatment acrosome loss was increased and sperm motility was slightly inhibited. Our results suggest that actin participate in calmodulin translocation to the postacrosomal region during acrosome reaction, in maintaining the acrosome structure, and perhaps also in sperm motility. © 1992 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080330209
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  • 3
    Electronic Resource
    Electronic Resource
    DNA synthesis and cell division related to adipose differentiation of 3T3 cells (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 114 (1983), S. 39-44 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Adipose differentiation of 3T3-F442A cells in surface cultures depends on adipogenic factor present in the culture medium. We found that after stimulation with adipogenic serum, 3T3T442A cell underwent a burst of DNA synthesis before adipose conversion was manifested by an augmented li-pogenic enzyme activity. In differentiating cells, DNA synthesis, judged by a 100-fold higher rate of [3H]thymidine incorporation into TCA-insoluble material, was followed by a 100-fold increase in the activity of glycero-phosphate acyltransferase. Cytosine arabinoside, added to the cultures at a concentration of 3 μg/ml, exerted 95% inhibition of [3H]thymidine incorporation and also inhibited adipose conversion. The burst of DNA synthesis correlated with a 2.5-fold increase in the amount of DNA and in the number of cells in the culture. The DNA content was the same in differentiated and nondifferentiated cells. We conclude that after the interaction with the adipogenic factor, the cells go through DNA synthesis and cell division essential for adipose conversion.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041140107
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  • 4
    Electronic Resource
    Electronic Resource
    Sperm tail differentiation in the nudibranch mollusc Hypselodoris tricolor (gastropoda, opisthobranchia) (1988)
    New York, NY : Wiley-Blackwell
    Gamete Research 20 (1988), S. 223-232 
    Details
    ISSN: 0148-7280
    Keywords: nudibranch ; axoneme ; basal body ; centriolar adjunct ; mitochondrial derivative ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The sperm axoneme of Hypselodoris tricolor forms from a single centriole that is located initially beneath the plasma membrane and then migrates to the nuclear surface. A conspicuous centriolar adjunct-like formation is present in the neck of midspermatids, but it becomes very reduced at the end of spermiogenesis. In spermatocyte and spermatid mitochondria, intracristal bodies originate from the accumulation of a dense material in some cristae. From our observations and foregoing reports, it may be concluded that the process of sperm tail differentiation in opisthobranchs resembles that in pulmonates, whereas it differs in many respects from that occurring in prosobranchs. The appearance of intracristal bodies in modified mitochondria seems to be a special feature of spermatogenesis in the opisthobranchs that does not occur in the two other groups of gastropod molluscs.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120200212
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  • 5
    Electronic Resource
    Electronic Resource
    Nuclear morphogenesis during spermiogenesis in the nudibranch molluscHypselodoris tricolor (Gastropoda, opisthobranchia) (1986)
    New York, NY : Wiley-Blackwell
    Gamete Research 13 (1986), S. 159-171 
    Details
    ISSN: 0148-7280
    Keywords: nudibranch ; spermiogenesis ; nuclear morphogenesis ; chromatin condensation ; manchette ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: An electron microscope study was carried out on Hypselodoris tricolor spermatids to describe the development of the nuclear morphogenesis and investigate the possible cause(s) of the change in the shape of the spermatid nucleus during spermiogenesis. Three different stages may be distinguished in the course of the nuclear morphogenesis on the basis of the morphology and inner organization of the nucleus. Stage 1 spermatid nuclei are spherical or ovoid in shape and the nucleoplasm finely granular in appearance. Stage 2 nuclei exhibit a disc- or cup-shaped morphology, and the chromatin forms short, thin filaments. During stage 3, a progressive nuclear elongation takes place, accompanied by chromatin rearrangement, first into fibers and then into lamellae, both formations helically oriented. A row of microtubules attached to the nuclear envelope completely surrounds the nucleus. Interestingly, the microtubules always lie parallel to the chromatin fibers adjacent to them. Late stage 3 spermatids show the highest degree of chromatin condensation and lack the manchette at the end of spermiogenesis. Our findings indicate the existence of a clear influence exerted on the chromatin by the manchette microtubules, which appear to be involved in determining the specific pattern of chromatin condensation in Hypselodoris tricolor.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120130209
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  • 6
    Electronic Resource
    Electronic Resource
    Ca2+ influx, phosphoinositide hydrolysis, and histamine release induced by lysophosphatidylserine in mast cells (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 165 (1995), S. 89-95 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have previously demonstrated that snake venom phospholipases A2 (PLA2s) and mammalian PLA2s induced inflammatory processes. This effect was correlated with the activity of the enzymes and the release of lipid mediators. We have now determined the role of lysophosphatidylserine (LysoPS) as an inflammatory lipid mediator. Thus, we have studied the possibility that intracellular calcium concentration, phosphoinositide hydrolysis, and the subsequent histamine release in mast cells is due to the action of lysophosphatidylserine. Lysophosphatidylserine-stimulated release of histamine was significantly higher than release by other lysophospholipids. The contribution of increased phospholipase C activity and the intracellular Ca2+ influx were therefore examined. LysoPS increased mast cell calcium concentration, and this increment was associated with phospholipase C activation and release of inositol phosphates. The increase in intracellular calucium and histamine degranulation induced by LysoPS were inhibited by apomorphine. Pretreatment of mast cells with pertussis toxin decreased the secretagogic effect of LysoPS and compound 48/80 without modifying the effect of the ionophore A23187. These results suggest that pertussis toxinsensitive G-protein might be involved in the mast cell degranulation produced by lysophosphatidylserine and allow the increase in phospholipase C activity, thus enhancing intracellular calcium concentration, which then induces exocytosis of histamine. © 1995 Wiley-Liss Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041650112
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  • 7
    Electronic Resource
    Electronic Resource
    Purification of isocitrate lyase from Saccharomyces cerevisiae (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 4 (1988), S. 41-46 
    Details
    ISSN: 0749-503X
    Keywords: Isocitrate lyase ; purification ; Catabolite inactivation ; Saccharomyces cerevisiae ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Isocitrate lyase purified to homogeneity from Saccharomyces cerevisiae was composed of four identical subunits with a molecular mass 75 K Da. The enzyme was most active at pH 7.0 in the presence of 5 mM-Mg2+. The Km value for threo-Ds-isocitrate was 1.4 mM. Isocitrate lyase was shown to be thermostable at 50°C for 60 min at a high salt concentration, but rapidly lost activity at -20°C or by dialysis.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/yea.320040105
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  • 8
    Electronic Resource
    Electronic Resource
    Role of the Cytoskeleton in Endocytosis of the Yeast Maltose Transporter (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 13 (1997), S. 541-549 
    Details
    ISSN: 0749-503X
    Keywords: cytoskeleton ; endocytosis ; yeast maltose transporter ; Saccharomyces cerevisiae ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Certain components of the cytoskeleton play a role in yeast fluid-phase endocytosis as well as in endocytosis of the α-factor when this pheromone is bound to its 7-transmembrane segment receptor. The yeast maltose transporter is a 12-transmembrane segment protein that, under certain physiological conditions, is degraded in the vacuole after internalization by endocytosis. In this work, the possible role of the cytoskeleton in endocytosis of this transporter has been investigated. Using mutants defective in β-tubulin, actin and the actin-binding proteins Sac6 and Abp85, as well as nocodazole, which inhibits formation of microtubules, we have shown that actin microfilaments are involved in endocytosis of the maltose transporter whereas microtubules are not.© 1997 John Wiley & Sons, Ltd.
    Additional Material: 4 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Inhibition of glycolysis by 2-deoxygalactose in Saccharomyces cerevisiae (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 8 (1992), S. 107-115 
    Details
    ISSN: 0749-503X
    Keywords: Yeast ; Saccharomyces cerevisiae ; glycolysis ; hexokinase ; phosphofructokinase ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The enzymatic steps involved in the inhibition of glycolysis by 2-deoxygalactose in Saccharomyces cerevisiae have been investigated. Yeast, incubated with 2-deoxygalactose, accumulates up to 8 mM-2-deoxygalactose, 30 mM-2-deoxygalactose-1-phosphate and 0·25 mM-UDP-2-deoxygalactose and UDP-2-dexyglucose. An inverse correlation between 2-deoxygalactose-1-phosphate content and rate of glycolysis has been observed. The intracellular concentration of glycolytic intermediates and related metabolites point to the hexokinase and phosphofructokinase steps as the targets for the inhibition of glycolysis by 2-deoxygalactose and rule out all other mechanisms that have been proposed to explain this inhibition.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/yea.320080205
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  • 10
    Electronic Resource
    Electronic Resource
    The peroxisomal membrane proteins of Candida boidinii: Gene isolation and expression (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 10 (1994), S. 1447-1457 
    Details
    ISSN: 0749-503X
    Keywords: Candida boidinii ; methylotrophic yeasts ; peroxisomes ; membrane proteins ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Candida boidinii is a methylotrophic yeast in which several growth substrates can cause vigorous peroxisomal proliferation. While such diverse substrates as methanol, oleic acid and D-alanine induce different peroxisomal metabolic pathways, membranes seem to contain common abundant peroxisomal membrane proteins (PMPs). These proteins have been termed PMP31, PMP32 and PMP47. The gene encoding PMP47 has been previously cloned and analysed. We now report the isolation of a second PMP47 gene (or allele) as well as PMP31 and PMP32. PMP47A and PMP47B share 95% sequence identity at the amino acid level. PMP31 and PMP32 each contain 256 amino acids and are highly similar (97% identity) in protein sequence. Both PMP31 and PMP32 are predicted to span the membrane once or twice. All abundant PMPs of C. boidinii are basic in charge; they all have predicted isoelectric points above 10. RNAs corresponding to the PMP47s and to PMPs31-32 are strongly induced by methanol, oleic acid and D-alanine. While the PMP47s probably encode substrate carriers, the functions of PMP31 and PMP32 from C. boidinii are still unknown. The GenBank Accession Numbers for PMP47B, PMP31, and PMP32 are L27998, L27999 and L28000, respectively. The 5′ untranslated sequence of PMP47A, accession number J05672, has been corrected.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/yea.320101108
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