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  • 1
    Electronic Resource
    Electronic Resource
    Middle-ear development: II. Morphometric changes in the conducting apparatus of the chick (1992)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 212 (1992), S. 257-267 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ontogeny of various middle-ear structures was examined in 11 groups of chicks between 10 days embryonic and adult. Measurements of the tympanic membrane surface area and height, columella length, and that of the columella footplate, annular ligament, and oval window area were obtained using video micrographs and computer digitization techniques. The oval window matures first at 53 days post-hatching, whereas the columella achieves adult size at 74 days. The tympanic membrane surface area is the last middle-ear variable studied to reach adult size (79 days post-hatch). The columella increases its length from 0.63 mm (10 days embryonic) to 2.73 mm in the adult. The tympanic membrane area expands by 280% whereas the columellar footplate area increases by 11x. As a result, the pressure amplification of the middle ear due to the tympanic membrane/columellar footplate area ratio improves by over 400%. These data further contribute to our understanding of the functional development of the middle ear. © 1992 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052120305
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  • 2
    Electronic Resource
    Electronic Resource
    Structural evidence for contractile units in the giant smooth muscle cell of Beröe (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 153-158 
    Details
    ISSN: 0886-1544
    Keywords: giant smooth muscle fiber ; ctenophore ; myofilaments ; ultrastructure ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Bundles of giant smooth muscle fibers of the ctenophore Beröe have been stretched up to four times their initial length and then examined by transmission electron microscopy. Stretching induces the segregation of actin and thick (myosinlike) filaments into separate domains. The thick filaments domains are made of 20-30 filaments, with a regular spacing identical to that of nonstretched fibers. A moderate stretching permits the visualization of microtendons associating actin filament bundles to hyaluronidase-resistant condensations of the extracellular matrix. It is deduced from these observations that Beröe giant smooth muscle fibers possess myofibrils which attach at both ends upon the sarcolemmal membrane. Each myofibril is probably made of two long actin filament bundles (of approximately 150 filaments) and short (2-3 μm) myosinlike bundles (of approximately 30 filaments).
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060213
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  • 3
    Electronic Resource
    Electronic Resource
    Mechanism-based isocoumarin inhibitors for serine proteases: Use of active site structure and substrate specificity in inhibitor design (1989)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 39 (1989), S. 33-46 
    Details
    ISSN: 0730-2312
    Keywords: anticoagulants ; blood coagulation enzymes ; elastase ; emphysema ; isocoumarins ; molecular modeling ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Isocoumarins are potent mechanism-based heterocyclic irreversible inhibitors for a variety of serine proteases. Most serine proteases are inhibited by the general serine protease inhibitor 3,4-dichloroisocoumarin, whereas isocoumarins containing hydrophobic 7-acylamino groups are potent inhibitors for human leukocyte elastase and those containing 7-alkylureidogroups are inhibitors for porcine pancreatic elastase. Isocoumarins containing basic side chains that resemble arginine are potent inhibitors for trypsin-like enzymes. A number of 3-alkoxy-4-chloro-7-guanidinoisocoumarins are potent inhibitors of bovine thrombin, human factor Xa, human factor XIa, human factor XIIa, human plasma kallikrein, porcine pancreatic kallikrein, and bovine trypsin. Another cathionic derivative, 4-chloro-3-(2-isothiureidoethoxy) isocoumarin, is less reactive toward many of these enzymes but is an extremely potent inhibitor of human plasma kallikrein. Several guanidinoisocoumarins have been tested as anticoagulants in human plasma and are effective at prolonging the prothrombin time. The mechanism of inhibition by this class of heterocyclic inactivators involves formation of an acyl enzyme by reaction of the active site serine with the isocoumarin carbonyl group. Isocoumarins with 7-amino or 7-guanidino groups will then decompose further to quinone imine methide intermediates, which react further with an active site residue (probably His-57) to form stable inhibited enzyme derivatives. Isocoumarins should be useful in further investigations of the physiological function of serine proteases and may have future therapeutic utility for the treatment of emphysema and coagulation disorders.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240390105
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  • 4
    Electronic Resource
    Electronic Resource
    Activation of phospholipase D by ras proteins is independent of protein kinase C (1996)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 61 (1996), S. 599-608 
    Details
    ISSN: 0730-2312
    Keywords: ras proteins ; growth factors ; phospholipase D ; PKC ; phorbol esters ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Growth factors activate phospholipases, causing the generation of diverse lipid metabolites with second messenger function. Among them, the phosphatidylcholine-preferring phospholipase D (PLD) has attracted great interest, since in addition to the transient activation by growth factors stimulation, it is constitutively activated in some of the src- and ras-transformed cells investigated. To establish further the functional relationship of ras oncogenes with PLD, we have investigated its mechanism of regulation. Growth factors such as PDGF or FGF activate the PC-PLD enzyme by a common, PKC-dependent mechanism. By contrast, ras oncogenes activate the PC-PLD enzyme by a PKC-independent mechanism. These results suggest the existence of at least two mechanisms for PLD activation, and ras oncogenes contribute to one of them. © 1996 Wiley-Liss, Inc.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Histochemical and ultrastructural study of the digestive tract of the tortoise Testudo graeca (Testudines) (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 204 (1990), S. 235-245 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The digestive tract of the tortoise Testudo graeca (Testudines) was investigated by means of light and electron microscopy. The esophagus of T. graeca was lined by two types of epithelium: non-keratinized stratified squamous in the upper portion and stratified columnar in the lower. The lamina propria of the esophagus contained tubular or tubuloacinar glands. The mucosa of the stomach showed similar characteristics to those of other reptiles. The small intestine exhibited longitudinal folds lined by absorptive and goblet cells. The large intestine was lined by columnar mucous cells. Within the lamina propria of the large intestine, masses of 10-15 epithelial cells connecting with the surface epithelium by means of slender cytoplasmic processes were observed. A battery of six lectins (Con-A, PNA, WGA, DBA, SBA, and LTA) was used to identify the epithelial mucins. WGA and DBA reacted with all types of mucous cells throughout the alimentary canal. PNA was only unreactive in the intestine, LTA in the esophagus, and SBA in the large intestine. These results indicate a similar lectin-binding pattern throughout the gut of T. graeca.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052040302
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  • 6
    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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  • 7
    Electronic Resource
    Electronic Resource
    Expression of bovine trophoblast interferons by in vitro-derived blastocysts is correlated with their morphological quality and stage of development (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 36 (1993), S. 1-6 
    Details
    ISSN: 1040-452X
    Keywords: Blastocyst ; Embryo ; Embryonic development ; In vitro fertilization ; Trophectoderm ; Trophoblast interferon ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Bovine embryos, whether produced naturally or by in vitro techniques, exhibit considerable variability in morphological quality and develop at different rates. Our objectives have been to determine whether initial expression of trophoblast interferon (IFN-τ) was a reflection of conceptus stage of development or age and whether there was an effect of embryo quality on the amount of IFN-τ produced. Early blastocysts (N =187) were selected at the onset of blastocoele formation and cultured individually. Embryo quality (excellent, good, or fair: E, G, or F) and developmental stage (early, expanded and hatched blastocysts: BL, EBL, and HBL, respectively) were used in a 3 x 3 factorial complete randomized block design, each block (n = 4) consisting of batches of embryos produced from oocytes in different collections. Quality and developmental stage of embryos and IFN-τ released into the medium were assessed every 24 h. Production of IFN-τ (units/embryo/24 h) was greater (P 〈 0.01) among hatched blastocysts (HBL; 0.91 ± 0.08) than expanded blastocysts (EBL; 0.23 ± 0.04) and early blastocysts (BL; 0.05 ± 0.08). Embryos of similar developmental stage but differing by 2 days in age released equal amounts of IFN-τ. Expression of antiviral activity increased (P 〈 0.05) from 27% to 57% to 100% as development proceeded from BL to EBL and to HBL respectively. More IFN-τ was produced by HBL graded G (1.0 ± 0.1) or E (1.3 ± 0.1) than by those of F quality (0.5 ± 0.1). All blastocysts, whatever their quality and developmental stage, contained IFN-± mRNA. Therefore, developmental stage and quality of the embryos significantly influence the expression of IFN-±. The amount produced may be a useful objective indicator of embryo quality. © 1993 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080360102
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  • 8
    Electronic Resource
    Electronic Resource
    Binding of chemotactic peptide to the outer surface and to whole human spermatozoa with different affinity states (1988)
    New York, NY : Wiley-Blackwell
    Gamete Research 20 (1988), S. 233-239 
    Details
    ISSN: 0148-7280
    Keywords: human sperm ; membrane ; receptors ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Binding of N-formyl-methionyl-L-leucyl-[3H]phenylalanine (fML[3H]Ph) to human ejaculated spermatozoa and to its isolated plasma membrane was studied. Our data confirm the presence of specific receptors for f-MLPh in the human spermatozoa and suggest that whole spermatozoa receptors exist in two affinity states, one high-affinity, low-capacity specific receptor (Kd = 12.3 ± 0.5 nM, n = 22,285 ± 65,008 binding sites per sperm cell) and a second one (Kd = 700 ± 47 nM) that is not saturable, indicating a low-affinity, high-capacity nonspecific site. In contrast, sperm membrane showed only one class of binding site (Kd = 6.4 ± 0.12 nM), which was statistically different from that of the high-affinity binding site of intact spermatozoa. To explain this difference we discuss the possibility that first, the two binding affinities represent two interconvertible states of a single receptor population, which, depending on the metabolic activity of spermatozoa, may change its physicochemical properties; or second, they reflect two different processes, binding and/or transport into the spermatozoa.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120200213
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  • 9
    Electronic Resource
    Electronic Resource
    Heparin and glutathione: Physiological decondensing agents of human sperm nuclei (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 39-47 
    Details
    ISSN: 0148-7280
    Keywords: nuclei decondensation ; thiol reagents ; reduced glutathione ; glycosaminoglycan ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: It has been proposed that reduced glutathione (GSH) or other thiol reagents may partici pate in the basic mechanism by which sperm-decondensing activity is accomplished. How ever, in vitro, these reagents seem to be inactive and require the presence of other chemi cals, usually detergents. Heparin binds specifically to the sperm membrane and provokes the decondensation of human sperm and the activation of DNA transcription and synthe sis. However, the concentrations at which these effects occur seem to be higher than those expected under physiological conditions. In the present study, thiol reagents at 10 mM concentration, either alone or combined, were completely ineffective in inducing any sig nificant nuclear decondensation after prolonged exposures (24 hr) of incubation. Heparin, 153.8 μM, was capable of inducing only a small increase in nuclear swelling. However, GSH at concentrations as low as 0.1 mM in combination with heparin induces deconden sation of human sperm nuclei in vitro. When GSH concentration was kept constant at 5 mM, nuclear decondensation was induced with heparin at concentrations as low as 11.6 μM, and a maximal decondensation (90%) was obtained with only 21.6 μM of heparin. The latter is more than ten times less than the minimal active concentration of heparin used alone.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120230105
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  • 10
    Electronic Resource
    Electronic Resource
    The chromosome periphery during mitosis (1994)
    New York, NY : Wiley-Blackwell
    BioEssays 16 (1994), S. 179-185 
    Details
    ISSN: 0265-9247
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A complex structure, visible by electron microscopy, surrounds each chromosome during mitosis. The organization of this structure is distinct from that of the chromosomes and the cytoplasm. It forms a perichromosomal layer that can be isolated together with the chromosomes. This layer covers the chromosomes except in centromeric regions. The perichromosomal layer includes nuclear and nucleolar proteins as well as ribonucleoproteins (RNPs). The list of proteins and RNAs identified includes nuclear matrix proteins (perichromin, peripherin), nucleolar proteins (perichro-monucleolin, Ki-67 antigen, B23 protein, fibrillarin, p103, p52), ribosomal proteins (S1) and snRNAs (U3 RNAs). Only limited information is available about how and when the perichromosomal layer is formed. During early prophase, the proteins extend from the nucleoli towards the periphery of the nucleus. Thin cordon-like structures reach the nuclear envelope delimiting areas in which chromosomes condense. At telophase, the proteins are associated with the part of the chromosomes remaining condensed and accumulate in newly formed nucleoli in regions where chromatin is already decondensed. The perichromosomal layer contains several different classes of proteins and RNPs and it has been attributed various roles: (1) in chromosome organization, (2) as a barrier around the chromosomes, (3) involvement in compartmentation of the cells in prophase and telophase and (4) a binding site for chromosomal passenger proteins necessary to the early process of nuclear assembly.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bies.950160308
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