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  • Cell & Developmental Biology  (152)
  • 1990-1994  (132)
  • 1965-1969  (18)
  • 1940-1944  (2)
  • 1
    ISSN: 1040-452X
    Keywords: Embryonic stem cells ; Cell differentiation ; Pluripotency ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Ten embryonic stem (ES) cell lines from mink blastocysts were isolated and characterized. All the lines had a normal diploid karyotype; of the ten lines studied, five had the XX and five had the XY constitution. Testing of the pluripotency of the ES-like cells demonstrated that (1) among four lines of genotype XX, an X was late-replicating in three; both Xs were active in about one-third of cells of line MES8, and analysis of glucose-6-phosphate dehydrogenase revealed no dosage compensation for the X-linked gene; (2) when cultured in suspension, the majority of lines were capable of forming “simple” embryoid bodies (EB), and two only showed the capacity for forming “cystic” multilayer EBs. However, formation of ectoderm or foci of yolk sac hematopoiesis, a feature of mouse ES ceils, was not observed in the “cystic” EB; (3) when cultured as a monolayer without feeder, the ES cells differentiated into either vimentin-positive fibroblast-like cells or cytokeratin-positive epithelial-like cells (less frequently); neural cells appeared in two lines; (4) when injected into athymic mice, only one of the four tested lines gave rise to tumors. These were fibrosarcomas composed of fibrobalst-like cells, with an admixture of smooth muscular elements and stray islets of epithelial tissue; (5) when the ES cells of line MES1 were injected into 102 blastocyst cavities and subsequently transplanted into foster mathers, we obtained 30 offspring. Analysis of the biochemical markers and coat color did not demonstrate the presence of chimaeras among offspring. Thus the cell lines derived from mink blastocysts are true ES cells. However, their pluripotential capacities are restricted. © 1992 Wiley-Liss, Inc.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 34 (1993), S. 53-57 
    ISSN: 1040-452X
    Keywords: Spermatozoa ; Gene expression ; Mutation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Basic chromosomal proteins were extracted from the sperm of fertile and infertile human males. The relative proportions of protamine 1, 2, and 3 were determined by scanning microdensitometry following electrophoresis of total protamine in polyacrilamide gels. The findings were as follows: (1) The proportion of protamine P(2 + 3) in sperm obtained from infertile males was lower than that in fertile males. (2) Protamine P(2 + 3) in infertile human males showed reduced affinity to DNA. The possibility that some cases of human male infertility may be due to mutation within the protamine P2 gene is discussed. © 1993 Wiley-Liss, Inc.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 39 (1994), S. 384-391 
    ISSN: 1040-452X
    Keywords: Transgene ; Mouse ; Embryo ; Microinjection ; PCR ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The production of transgenic animals from ungulate species is an inefficient and expensive procedure. The development of selection methods to identify the small number of transgenic preimplantation embryos produced following DNA microinjection of one-cell embryos would greatly reduce both the cost and effort of these procedures. This study has examined the fate of the ovine β-lactoglobulin-human α1-antitrypsin (AATB) minigene construct or a subfragment of this following microinjection into one-cell mouse embryos. It has examined two PCR-based methods that were designed to identify a biochemical difference between microinjected DNA constructs to select preimplantation stage embryos in which chromosomal integration of exogenous DNA has occurred. The two methods involved the modification of the AATB DNA construct either by dam-methylation or the substitution of dTTP by dUTP. The dam-sensitive DNA endonuclease Dpnl, that was used to digest nonintegrated AATB sequences at sites located between PCR oligonucleotide sequences, was found to interfere with the activity of the subsequent PCR reaction. Analyses of the fate of dUTP-DNA indicated that either repair or replication of microinjected DNA interfered with the ability to distinguish between integrated and nonintegrated DNA constructs in the mid-preimplantation stage embryo. The distribution of microinjected AATB DNA between the blastomeres of individual four and eight-cell stage embryos was also examined by the PCR reaction. Microinjected DNA was not found to be evenly distributed between all the blastomeres of individual embryos. © 1994 Wiley-Liss, Inc.
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  • 4
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The tissue distribution of P-glycoprotein (Pgp) and the structurally related cystic fibrosis transmembrane conductance regulator (CFTR) is apparently mutually exclusive, particularly in epithelia; where one protein is expressed the other is not. To study the possible function(s) of Pgp and its potential effects on CFTR expression in epithelia, HT-29 colon adenocarcinoma cells, which constitutively express CFTR, were pharmacologically adapted to express the classical multidrug resistance (MDR) phenotype (Pgp+). Concomitant with the appearance of Pgp and MDR phenotype (drug resistance, reduced drug accumulation and increased drug efflux), CFTR levels and cAMP-stimulated Cl conductances were markedly decreased compared to wild-type HT-29 (Pgp-) cells (as shown using the whole cell patch clamp technique). Removal of drug pressure led to the gradual decrease in Pgp levels and MDR phenotype, as evidenced by increased rhodamine 123 accumulation (Pgp-Rev). Concomitantly, CFTR levels and cAMP-stimulated Cl- conductances incresed. The cell responses of Pgp/Rev cells were heterogeneous with respect to both Pgp and CFTR functions. We also studied the possible contribution of Pgp to hypotonically activated (HCS) ion conductances. K+ and Cl- effluxes from Pgp- cells were markedly increased by HCS. This increase was twice as high as that induced by the cation ionophore gramicidin; it was blocked by the Cl- channel blocker DIDS (4,4′-disothiocyano-2,2′-disulfonic stilbene) and required extracellular Ca2+. In Pgp+ cells, the HCS-induced fluxes were not significantly different from those of Pgp- cells. Verapamil (10 μM), which caused 80% reversal of Pgp-associated drug extrusion, failed to inhibit the HCS-evoked Cl- efflux of Pgp+ cells. Similarly, HCS increased Cl- conductance to the same extent in Pgp-, Pgp+ and Pgp-Rev cells. Verapamil (100 μM), but not 1,9-dideoxyforskolin (50 and 100 μM), partially inhibited the HCS-evoked whole cell current (WCC) in all three lines. Since the inhibition by verapamil was not detected in the presence of the K+ channel blocker Ba2+ (3 mM), it is suggested that verapamil affects K+ and not Cl- conductance. We conclude that hypotonically activated Cl- and K+ conductances are similar in HT-29 cells irrespective of Pgp expression. Expression of high levels of Pgp in HT-29 cells confers no physiologically significant capacity for cell volume regulation. © 1994 Wiley-Liss, Inc.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 66 (1940), S. 481-495 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 6
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The complete regeneration of a new oral-disc and tentacles has been observed and described for Aiptasia diaphana. These structures are regenerated quite rapidly: seven to ten days at 20°C. At three days post-amputation, the new primary, secondary, and tertiary tentacle buds begin to develop in direct association with the underlying primary, secondary, and tertiary septae (respectively) of the column, suggesting that the latter organize the form of the regenerating oral-disc. Two days after amputation, the zooxanthellae of the presumptive oral disc arrange themselves into a ring which quite precisely delimits the area from which the tentacle buds will form. In spite of its suggestive proximity, this accumulation of algae plays no role in the induction of tentacle buds as was shown by studying regeneration in anemones which essentially lacked large quantities of these symbiotic algae.Cuts perpendicular to the longitudinal axis of the column result in an equal rate of tentacular regeneration around the entire circumference of the presumptive oral disc. Oblique amputations foster an asynchronous regeneration: the tentacle buds of the distal-most area of the severed column are larger and regenerate much sooner than those of the proximal region. Similar results were obtained by studying anemones which were cut perpendicular to their longitudinal axes at different levels along the column. The data suggest that an oral-aboral gradient exists concerning the time required for the initiation of tentacle budding and the rate of tentacle regeneration.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 211 (1992), S. 243-258 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Subdigital adhesive pads play an important role in the locomotion of many species of gekkonid lizards. These pads consist of integrated components derived from the epidermis, dermis, vascular system, subcuticular tendons, and phalanges. These components become intimately associated with each other during the developmental differentiation of the digits and the sequence of this integration is outlined herein in Ptyodactylus guttatus. The pads initially appear as paired swellings at the distal tips of the digits. Subsequently, a fan-like array of naked scansors develops on the ventral surface of each digit, at about the same time that scales differentiate over the surface of the foot as a whole. At the time of appearance of the naked scansors, the vascular sinus system of the pad also differentiates, along with subcuticular connective tissue specializations. At this stage the digits, along with the rest of the body, are clad in an embryonic periderm. Only after hatching and as the periderm is shed, do the epidermal setae and spines appear. The developmental sequence described here is consistent with predictions previously advanced about the evolutionary origin and elaboration of subdigital pads in gekkonid lizards. The paucity of available staged embryonic material leaves many questions unresolved.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 214 (1992), S. 341-350 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Representative functional teeth from Cryptobranchus alleghaniensis (Cryptobranchidae), Amphiuma means (Amphiumidae), Dicamptodon ensatus (Dicamptodontidae), Necturus maculosus (Proteidae), and Dermophis sp. (Costa Rica) (Caeciliidae) were prepared for transmission electron microscope and electron microprobe analysis of the trace elements of the enamel layer. The enamel layer of these species is very thin and the arrangement of enamel crystals variable. In particular, the outer part of the enamel layer in which hydroxyapatite elements (Ca, P) and trace elements (e.g., F, Fe, Mg) are concentrated, is most heavily mineralized. The concentrations and alignment of crystals in the outer and inner parts of the enamel layer differ among these species.The presence of collagen fibers in the inner part of the enamel layer of Cryptobranchus and Dermophis indicates that it is enameloid rather than true enamel. The presence of trace elements may be related to the pattern of mineralization of enamel or enameloid, as suggested for tetra-odontiform fishes by Suga et al. (J. Dent. Res. 68:1115-1123, 1989). © 1992 Wiley-Liss, Inc.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 217 (1993), S. 171-181 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the American alligator, the jaw muscles show seven bundles of tendinous structure: cranial adductor tendon, mandibular adductor tendon, lamina anterior inferior, trap-shaped lamina lateralis, lamina intramandibularis, lamina posterior, and depressor mandibular tendon (originating from the musculus depressor mandibulae, m. pseudotemporalis, m. adductor mandibulae posterior, m. adductor mandibulae externus, m. intramandibularis, m. pterygoideus anterior, and m. pterygoideus posterior). These tendinous structures are composed of many collagen fibrils and elastic fibers; however, the distributions and sizes of the fibers in these tendinous components differ in comparison with those of other masticatory muscles. The differences of these properties reflect the kinetic forces or the stretch applied to each tendon by the muscle during jaw movements in spite of the simple tendon-muscle junctions. © 1993 Wiley-Liss, Inc.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 219 (1994), S. 35-46 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Embryos of viviparous goodeid fishes undergo a 10 to 150 × increase in dry weight during gestation. Maternal nutrients are transferred across a trophotaenial placenta comprised of the ovarian lumenal epithelium and the trophotaeniae of the embryo. Trophotaeniae are externalized projections of the embryonic hindgut. Epithelial cells of the ribbon trophotaenia (Ameca splendens) resemble intestinal absorptive cells of suckling mammals and endocytose macromolecules. They possess an apical brush border, endocytotic complex, endosomal-lysosomal system, and apical and basal clusters of mitochondria. Cells of the rosette trophotaenia (Goodea atripinnis) lack an endocytotic apparatus, have small lysosomes, two mitochondrial clusters, and transport small molecules. Organelle-specific fluorescent probes were employed to characterize the functional organization of the two types of trophotaenial cells. In A. splendens, Lucifer Yellow, a membrane-impermeable tracer of vesicular transport, first appears in peripheral vesicles (15-45 sec), then passes into elongated tubular endosomes (1-3 min) and later appears in large central vacuoles (10-15 min). These vacuoles accumulate Acridine Orange, a classical probe for lysosomes, and have been shown to contain lysosomal enzymes. Endosomelysosome fusion was observed. In both A. splendens and G. atripinnis, Rhodamine 123 fluorescence was localized in two clusters of fine spots that corresponded to mitochondria. 4′,6-diaminido-2-phenyl-indole (DAPI) staining of nuclei established the positional relationships of cell organelles with respect to the nuclei. 3,3′-dihexyloxacarbo-cyanine iodide (DiOC6) revealed the perinuclear distribution of the endoplasmic reticulum. In order to compare in vivo fluorescence of Lucifer Yellow with previous ultrastructural observations, we employed fluorescence photoconversion and electron microscopy. © 1994 Wiley-Liss, Inc.
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