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  • 1
    Electronic Resource
    Electronic Resource
    Chromatin condensation in hamster sperm: A flow cytometric investigation (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 37 (1994), S. 93-98 
    Details
    ISSN: 1040-452X
    Keywords: Chromatin condensation ; DNA packaging ; Spermatozoa ; Hamster ; Acridine orange ; Flow cytometry ; Bromobimane ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In this study we have used acridine orange staining, as described by Evenson (1990), to follow changes in DNA packaging as they occur in hamster spermatozoa which have left the testis and are undergoing maturation in the epididymis. Measurement of the green and red fluorescent intensities of hamster sperm nuclei by flow cytometry demonstrated a decrease in acridine orange binding to DNA as sperm made their way from proximal corpus epididymis to the vas deferens. Using sperm from the cauda epididymis of the mature hamster as the standard, a method was developed for estimating the % of cells in a given sample that have matured with regard to DNA packaging. Staining with bromobimane was used to determine the extent of sulfhydryl oxidation in the nuclei. It was seen that sulfhydryl oxidation occurred mainly in the cauda epididymis whereas another process in chromatin condensation occurred earlier, during sperm passage through the caput epididymis. This earlier process could be mimicked by incubating sperm nuclei with alkaline phosphatase, suggesting that it consists of removal of phosphate in protamine. © 1994 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080370113
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  • 2
    Electronic Resource
    Electronic Resource
    The modified midventral scales of Percina (Osteichthyes; Percidae) (1976)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 148 (1976), S. 255-264 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The modified midventral scales on Percina males probably function to induce tactile stimulation of the female during spawning. The midbelly row of modified scales presumably evolved as a result of increased selective advantage of larger and more strongly toothed scales on the midventer; primitive and intermediate conditions in the evolution of the modified scales as well as a distinctly modified row are extant, The morphology of the scales varies seasonally and ontogenetically. The scales are permanent rather than deciduous as described in the literature interspecific variation of the modified scales is pronounced intersubgenerically. less so intrasubgenerically.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051480209
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  • 3
    Electronic Resource
    Electronic Resource
    Homology of facial structures in extant archosaurs (birds and crocodilians), with special reference to paranasal pneumaticity and nasal conchae (1995)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 225 (1995), S. 269-327 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Homology of virtually all major components of facial anatomy is assessed in Archosauria in order to address the function of the antorbital cavity, an engimatic structure that is diagnostic for the group. Proposed functions center on its being a housing for a gland, a muscle, or a paranasal air sinus. Homology is approached in the context of the Extant Phylogenetic Bracket method of reconstructing unpreserved aspects of extinct organisms. Facial anatomy and its ontogeny was studied in extant archosaurs (birds and crocodilians) to determine the osteological correlates of each soft-tissue component; resemblances between birds and crocodilians comprised the similarity test of homology. The congruence test of homology involved surveying phylogenetically relevant fossil archosaurs for these bony signatures. The facial anatomy of extant birds and crocodilians is examined in detail to provide background and to discover those apomorphic aspects that contribute to the divergent specialization of these two groups and thus obscure homologies. Birds apomorphically show enlarged eyeballs, expanded nasal vestibules, and reduced maxillae, whereas crocodilian faces are dorsoventrally flattened (due to nasal rotation) and elongated. Most facial attributes of archosaurs are demonstrably homologous and in fact characterize much more inclusive groups. Special emphasis has been placed on the nasal conchae and paranasal air sinuses. Within Amniota, the following conchal structures are homologous, and all others are neomorphs: Avian caudal concha, crocodilian concha + preconcha, Sphenodon caudal concha, squamate concha, and probably the mammalian crista semicircularis. The avian antorbital paranasal air sinus is homologous with the crocodilian caviconchal sinus; the maxillary sinus of placental mammals is not homologous with the archosaurian paranasal sinus. With regard to the function of the antorbital cavity, archosaurs possess homologous nasal glands, dorsal pterygoideus muscles, and paranasal air sinuses, but the osteological correlates of only the paranasal sinus involve the antorbital fenestrae and fossae. Thus, the antorbital cavity is best interpreted as principally a pneumatic structure. © 1995 Wiley-Liss, Inc.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052250304
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of germanium on the morphology of silica deposition in a freshwater sponge (1979)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 159 (1979), S. 343-353 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effect of germanium on the secretion of siliceous spicules by the freshwater sponge Spongilla lacustris was investigated by exposing germinating and hatching gemmules to varying concentrations of germanium (Ge) in the presence of silicon (Si). Results were analyzed quantitatively and qualitatively and demonstrate that a [Ge]/[Si] (= molar ratio) of 1.0 completely inhibits silicon deposition. Intermediate ratios (0.5, 0.1, 0.01) which are permissive to spicule appearance result in fewer, shorter, and thinner spicules, in proportionately fewer microscleres, and in short bulbous megascleres. The size of the bulb increases with increasing [Ge]/[Si], while the length of the bulbous megascleres decreases with increasing [Ge]/[Si]. Microscleres do not demonstrate these graded responses suggesting that they are secreted in an all or none manner. Swellings produced in pond water and bulbs produced in germanium appear to decrease in size with time indicating a spreading of the accumulated silica. The effect of germanium on spicule secretion can be partially explained by its ability to uncouple the growth in length of the axial filament from the growth of the surrounding silicalemma. Under these conditions excess silicalemma is produced in which silica accumulates as bulbs in short spicules. Continuous exposure to Ge is necessary to produce this altered morphology. It is conjectured that the bulbs may be retained due to an inhibition of spreading. which in turn may be caused by the incorporation of germanium into the silica.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051590305
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  • 5
    Electronic Resource
    Electronic Resource
    Genes that regulate apoptosis in the mouse thymus (1996)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 60 (1996), S. 18-22 
    Details
    ISSN: 0730-2312
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Elimination of self-reactive T lymphocytes occurs during T-cell development in the thymus by a process known as negative selection. The mechanism that drives negative selection is apoptosis. To identify genes that regulate apoptosis in the mouse thymus, a library of negatively selected T cells was constructed and, by subtractive screening, several differentially regulated genes were isolated. Two transcripts that are repressed during cell death were identified, in addition to two induced transcripts. Further experiments demonstrated that cell death in thymocytes can occur via several induction pathways and each pathway appears to be regulated by a unique cascade of genes. © 1996 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Transepithelial transport in cell culture: Bioenergetics of Na-, D-glucose-coupled transport (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 114 (1983), S. 263-266 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The renal cell line LLC-PK1 contransports Na and D-glucose from the apical to the basolateral side of the cell monolayer, and the short-circuit current (Isc) measures the net amount of Na transported. Under conditions of maximal cotransport, the addition of phlorizin or removal of Na rreversibly decreased oxygen consumption by one-hal. In the absence of glycolytic substrates, α-methyl-D-glucoside stimulated Isc and oxygen consumption, although the Isc came to a steady state 50% less than when glycolytic substrates were present. The addition of other aerobic substrates did not increase Isc; however, when non-contransported glycolytic substrates were introduced the Isc returned to a maximum with an associated fall in oxygen consumption and increased lactate production. Thus, in the absence of glycolytic substrates aerobic ATP formation may be rate-limiting for Na, D-glucose contansport. For this epithelium glycolysis makes an impotant contribution to the provision of energy or transport. Oxygen consumption does not correlate well with Isc and is not a good measured off the energy used in transport.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041140303
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  • 7
    Electronic Resource
    Electronic Resource
    Interferon inhibition of thymidine incorporation into DNA through effects on thymidine transport and uptake (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 121 (1984), S. 431-436 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Replenishment of medium after 72 hr of growth of HeLa-S3 cells in dense suspension cultures increased [3H]-thymidine uptake into cells and incorporation into DNA, with the levels reaching a peak ∼ 12 hr following medium change; β interferon inhibits the enhanced uptake of [3H]-thymidine and labeling of DNA in a dose-dependent manner. Some reduction in these processes is observed at a concentration as low as 1 u/ml, and ∼ 75% inhibition at 640 u/ml. Kinetic analysis has revealed that the rate of labeling of the acid-soluble pool with [3H]-thymidine, measured either at 22°C, or 37°C, is reduced in interferon-treated (640 u/ml, 24 hr) HeLa-S3 cells. At 22°C, the initial rate of thymidine transport at a high (500 μM) thymidine concentration, determined within the first 30 sec of [3H]-thymidine addition was depressed by 44% in interferon-treated HeLa cells. At 37°C, labeled precursors accumulate in acid-soluble material for ∼ 8 min after the addition of [3H]-thymidine, after which an apparent equilibrium level is attained. At this temperature, the rate of thymidine uptake and the apparent equilibrium level attained were depressed by 70% in interferon-treated HeLa cells. The reduced incorporation of [3H]-thymidine into DNA in interferon-treated HeLa-S3 cells can be largely explained by interferon inhibition of thymidine transport and phosphorylation.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041210223
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  • 8
    Electronic Resource
    Electronic Resource
    Regulation of plasma membrane protein phosphorylation in two mammalian cell types (1976)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 89 (1976), S. 815-826 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The appreciation of protein phosphorylation as a ubiquitous mechanism for the post-translational control of protein function has drawn our attention to the phosphorylation of plasma membrane proteins. We have studied this phenomenon in the human erythrocyte and rat adipocyte, and have observed several features, common to the two systems, which may be of general significance. In examining protein phosphorylation in intact cells incubated with 32Pi, it is evident that the 32P-polypeptides of the plasma membrane are among the most highly labelled species in the cell, despite their minor contribution to overall protein content. The addition of epinephrine (to adipocytes) or cAMPThe following abbreviations are used: cAMP, adenosine 3′:5′-cyclic monophosphate; DBcAMP, N6, O2′-dibutyryl adenosine 3′:5′-cyclic monophosphate; HEPES, N-2-hydroxyethylpiperazine-N1-2-ethanesulfonic acid; SDS, sodium dodecyl sulfate. (to erythrocytes) increases the phosphorylation of certain peptides, whereas others are unaffected. The protein kinases mediating these phosphorylations are present in the plasma membrane as isolated, and can be divided into two groups--cAMP dependent and cAMP independent. These two classes of kinase differ markedly in their substrate specificity toward endogenous and exogenous polypeptide substrates. Two classes of protein kinases with similar properties can be detected in the cytoplasm. The relationship between the membrane-bound and cytoplasmic enzymes is uncertain.The potential roles of the plasma membrane cAMP dependent protein kinases are evident from the diverse effects of cAMP on surface properties; however, the prevalence of plasma membrane proteins phosphorylated via cAMP independent pathways is striking. Thus, elucidation of the regulatory properties of the plasma membrane cAMP independent protein kinases may give new insight into the control of a variety of surface phenomena not mediated by cAMP.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040890449
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  • 9
    Electronic Resource
    Electronic Resource
    Differences in oxygen-dependent regulation of enzymes between tumor and normal cell systems in culture (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 108 (1981), S. 393-400 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Metabolic studies in tumor cells have indicated that bioenergetic regulatory mechanisms geared to acute changes in oxygen availability are abnormal. In the present studies we have examined bioenergetic adaptations to chronic oxygen depletion in culture maintained tumor cells in comparison to normal cell lines. Activities of two key glycolytic enzymes (pyruvate kinase (PyKi) and phosphofructokinase (PFK)) were measured in two tumor cell lines (fibrosarcoma (FS) and Hela) and two normal cell lines (rat lung fibroblasts (RLF) and WI-38) maintained in culture for up to 96 hours under aerobic (PO2 ∼ 140) and hypoxic PO2 ∼ (15) conditions. Exposure to low O2 tensions for 96 hours resulted in significant increases in PyKi and PFK in both RLF and WI-38, but did not alter activities of these enzymes in either FS or HeLa cell systems. Activities of two enzymes involved in O2 metabolism (cytochrome oxidase (CyOx)) and superoxide dismutase (SOD) were also measured in the two tumor cell lines and in RLF. Chronic hypoxia significantly decreased the activities of CyOx and SOD in RLF cell systems but did not alter the activities of these enzymes in the tumor cells. In these studies, the tumor-derived cell lines do not demonstrate specific enzymatic responses to sustained oxygen depletion in vitro noted in normal cell systems, suggesting significant abnormalities in regulatory mechanisms geared to chronic changes in molecular O2.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041080313
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  • 10
    Electronic Resource
    Electronic Resource
    Ced-3/ICE: Evolutionarily conserved regulation of cell death (1994)
    New York, NY : Wiley-Blackwell
    BioEssays 16 (1994), S. 387-389 
    Details
    ISSN: 0265-9247
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bies.950160604
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