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  • 1
    ISSN: 0749-503X
    Keywords: Saccharomyces cerevisiae ; glycolysis ; metabolism ; glucose ; trehalose ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Intracellular metabolic flux has been investigated in two strains of Saccharomyces cerevisiae grown into stationary phase under both glucose-repressed and glucose-derepressed conditions. By employing a variety of simple methodologies (manometry, enzymatic analysis and colorimetric analysis) we have been able to identify and quantitate carbon flow from glucose without the need for isotopically labelled substrate. We can account for 88-98% (depending on strain and growth conditions) of the carbon products of glucose metabolism under both glycolytic and oxidative conditions as ethanol (27-40%), carbon dioxide (15-26%), acetate (2-3%), glycerol (5-11%), glycogen (5-13%) and trehalose (9-39%).©1997 John Wiley & Sons, Ltd.
    Additional Material: 1 Ill.
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  • 2
    ISSN: 1040-452X
    Keywords: Embryo banking ; Vitrification ; Genotype effects ; Inbred strains ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We examined possible genotype effects on the survival of 8- to 16-cell mouse embryos isolated from four inbred strains (C57BL/6N, BALB/cAnN, DBA/2N, and C3H/HeN), a outbred stock (ICR), and various crosses after cryopreservation by vitrification or conventional slow freezing using glycerol solutions. The rates of in vitro development of C57BL/6N, BALB/cAnN, C3H/HeN, and ICR embryos to expanded blastocysts ranged from 86% to 94% after slow freezing and 85% to 97% after vitrification. The cryopreservation method did not significantly influence in vitro embryo survival after thawing (P 〉0.05). Although genotype significantly influenced the in vitro survival of embryos (P = 0.008), this presumably resulted from an increased difficulty in assessing the quality grade of C3H/HeN embryos prior to cryopreservation. The rates in vivo development of C57BL/6N, BALB/cAnN, C3H/HeN, DBA/2N, and ICR embryos to normal day 18-19 fetuses ranged from 19% to 64% after slow freezing and from 18% to 63% after vitrification. The in vivo development of cryopreserved embryos was significantly influenced by cryopreservation method and genotype (P = 0.01 and P = 0.001, respectively). Vitrification yielded significantly higher rates of in vivo development than that after slow freezing (P 〉 0.05). In vivo development rates of DBA/2N and ICR♀ X B6D2F1 ♂ embryos after cryopreservation were significantly higher than that of embryos from BALB/cAnN and C3H/HeN mice (P 〈 0.05). These results indicate that parental genotype exerts little or no effect on the ability of embryos to develop in vitro after vitrification or slow freezing. Differences in the ability of cryopreserved embryos to develop normally in vivo may reflect inherent genotype related differences in their post-implantation developmental potential and not their sensitivity to cryoinjury. © 1995 Wiley-Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
    Additional Material: 4 Tab.
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  • 3
    ISSN: 0886-1544
    Keywords: intermediate filaments ; vimentin ; myogenesis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Desmin and vimentin are two type III intermediate filament (IF) proteins, which can be phosphorylated in vitro by cAMP-dependent kinase (kinase A) and protein kinase C, and the in vitro phosphorylation of these proteins appears to favor the disassembled state. The sites of phosphorylation for desmin and vimentin have been mapped to their amino-terminal headpiece domains; in chicken smooth muscle desmin the most kinase A-reactive residues are ser-29 and ser-35. In this study we have examined the phosphorylation of desmin by the catalytic subunit of kinase A by using anti-peptide antibodies directed against residues 26-36. The antibodies, which we call anti-D26, recognize both native and denatured desmin and can discriminate between intact desmin and those derivatives that do not possess residues 26-36. Pre-incubation of desmin with affinity purified anti-D26 blocks total kinase A catalyzed incorporation of 32P into desmin by 75-80%. When antibody-treated IFs are subjected to phosphorylation, no filament breakdown is observed after 3 hours. Thus anti-D26 antibodies block phosphorylation of IF in vitro. We have also explored the role of desmin phosphorylation in skeletal muscle cell differentiation using these antibodies. Quail embryo cells, induced to differentiate along the myogenic pathway by infection with avian SKV retroviruses expressing the ski oncogene, were microinjected with affinity purified anti-D26 at the mononucleated, myoblast stage. By 24 h post-injection, the vast majority of uninjected cells had fused into multinucleated myotubes, but all microinjected cells were arrested in the process of incorporating into myotubes and remained mononucleated. This observation suggests that kinase A phosphorylation-induced dynamic behavior of the desmin/vimentin IF cytoskeleton may be one of the many cytoskeletal restructuring events that must take place during myoblast fusion.
    Additional Material: 8 Ill.
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  • 4
    ISSN: 0886-1544
    Keywords: intermediate filament proteins ; vimentin ; domain function ; filament assembly ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Although the head and rod domains of intermediate filament (IF) proteins are known to play significant roles in filament assembly, the role of the tail domain in this function is unclear and the available information supports contradictory conclusions. We examined this question by comparing transfection of the same cDNA constructs, encoding vimentins with modified tail domains, into cell lines that do and do not contain endogenous IF proteins. By this approach, we were able to distinguish between the ability of a mutant IF protein to initiate assembly de novo, from that of incorporating into existing filament networks. Vimentins with modifications at or near a highly conserved tripeptide, arg-asp-gly (RDG), of the tail domain incorporated into existing IF networks in vimentin-expressing (vim+) cells, but were assembly-incompetent in cells that did not express IF proteins (vim-). The failure of the RDG mutant vimentins to assemble into filament arrays in vim- cells was reversible by re-introducing a wild-type vimentin cDNA, whereupon both wild-type and mutant vimentins coassembled into one and the same IF network. We conclude that the function of the tail domain of type III IF proteins, and possibly of keratins K8 and K18, in IF assembly is distinct from those of other domains; a region encompassing the RDG tripeptide appears to be important in the assembly process. © 1994 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Clinical Anatomy 6 (1993), S. 280-288 
    ISSN: 0897-3806
    Keywords: femur ; anteversion ; ultrasound ; bones ; Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: This study evaluates the most valid and reproducible method for directly measuring anteversion (torsion) in dried femora using a commercially available measuring machine. Each femur was placed horizontally on the surface of the machine and readings were obtained from the head, the shaft distal to the lesser trochanter, and the distal end. Using computer software, four different anteversion angles were calculated: the center head-neck line to the retrocondylar line (Method 1); the center head-neck line to the transcondylar line (Method 2); the anterior head-trochanter line to the retrocondylar line (Method 3); and the anterior head-trochanter line to the transcondylar line (Method 4). The methods were applied to 20 femora, which were measured twice by one observer. The most reproducible method of measuring femoral anteversion uses the bone surfaces on the anterior aspect of the head and greater trochanter and on the posterior aspect of the condyles (Method 3.95% confidence limits of ± 0.4°). The other methods are shown to be reproducible to ±2.4°, ±3.3° and ±1.7° (Methods 1, 2, and 4, respectively, 95% confidence limits). Conversion factors between the different methods are: 12.5° + 0.8 x (anteversion angle) to change each of Method 2 to Method 1 and Method 4 to Method 3; and 8° + 0.7 x (anteversion angle) to change each of Method 1 to Method 3 and Method 2 to Method 4 (correct to within ±3°). © 1993 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
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  • 6
    ISSN: 0897-3806
    Keywords: hip ; knee ; femoral anteversion ; tibial torsion ; Life and Medical Sciences ; Miscellaneous Medical
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: In this paper, we introduce the concept of functional anteversion of the femur and its positional change. It emerged from studies using B-mode and real-time ultrasound to determine femoral anteversion in two knee positions. Twenty healthy children were scanned at the hips whilst lying supine with knees extended and then with the knees flexed to about 90°. The “anteversion” angle between the head-trochanter line and the horizontal measured with knees extended and feet together is determined by three factors: 1) anatomical femoral anteversion, 2) femoro-tibial rotation at the knee, and 3) tibial torsion. This is one type of “functional anteversion” of the femur.The best reproducibility for functional femoral anteversion was obtained by scanning with real-time ultrasound and the knees extended (95% confidence limits within ± 2.8°); the use of B-mode ultrasound in the knees-extended position is significantly less reproducible (95% confidence limits within ± 6.1°). In the flexed-knee position, the reproducibility is similar with both B-mode and real-time ultrasound (± 2.6-3.5°). Both positions have limitations in attempts to measure anatomical femoral anteversion by ultrasound.The functional femoral anteversion angle measured by B-mode and real-time ultrasound is significantly larger (by 9-10°) with the knees flexed than with the knees extended. This positional change of measured femoral anteversion involving axial rotation at the hip is attributed mainly to 1) lateral rotation (unlocking) of the femur at the knee during flexion from the fully extended position and 2) any lateral tibial torsion which rotates the femur nedially in the knees-extended position with the feet vertical. The considerable individual variation and asymmetry of this axial rotational change may have relevance to the etiology of certain clinical disorders of the spine, hip, and knee joints. © 1993 Wiley-Liss, Inc.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0741-0581
    Keywords: Ovary ; Vitellogenesis ; Follicle ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Oogenesis, the early events of primary oocyte growth (meiotic arrest, synapsis, ribosomal gene duplication), and folliculogenesis can be seen to particular advantage in the germinal ridge of the syngnathan ovary. After budding off the germinal ridge (a compartment of the luminal epithelium), nascent follicles then enter into a linear array of developing follicles within which temporal and stage-specific events can be correlated with spatial distribution. Prominent features of the later phase of primary oocyte growth include intense transcriptional activity and the formation and subsequent dispersal of the Balbiani vitelline body (mitochondrial cloud) concomitant with an increase in cytoplasmic organelles and volume. Further oocyte growth is characterized by a period of cortical alveolus (in teleosts) or cortical granule (in anurans) formation, in which Golgi elements play a predominant role, and finally vitellogenesis. The latter process, which is responsible for the preponderance of oocyte growth, includes the hepatic synthesis and secretion of vitellogenin (VTG), the uptake of VTG from the bloodstream into the oocyte by receptor-mediated endocytosis, and the transport of VTG via endosomes and multivesicular bodies to forming yolk platelets. In the process, VTG is proteolytically cleaved into the yolk proteins, which assume either a monoclinic (in cyclostomes) or orthorhombic (in teleosts and amphibians) crystalline array. Other structures associated with the growing oocyte are also briefly discussed, including nuage, the vitelline envelope, intercellular junctions between the oocyte and overlying follicle cells, pigment, intramitochondrial crystals in ranidae, and annulate lamellae.
    Additional Material: 20 Ill.
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  • 8
    ISSN: 1040-452X
    Keywords: Male sterility ; Modified HSV-1 thymidine kinase ; HSV-2 thymidine kinase ; Thyrocytes ; Conditional ablation ; Ganciclovir ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Previously we demonstrated that lines of transgenic mice carrying the herpes simplex type 1 virus thymidine kinase (HSV1-tk) reporter gene are malesterile. Ectopic transcription of the HSV1-tk reporter in the testis was initiated downstream of the normal translation initiation codon and truncated proteins consistent with translational initiation at the second and third ATG codons were synthesized. Here we describe the effects on fertility (1) of converting the second and third ATG codons of the HSV1-tk reporter to CTG codons and (2) of utilizing the HSV type 2 thymidine kinase (HSV2-tk) reporter gene, in which the second ATG codon is located downstream of the ATP-binding pocket of the enzyme. Both reporters were coupled to the bovine thyroglobulin promoter (bTG-tk1α and bTG-tk2 transgenes). The level of ectopic expression of these transgenes in the testis, relative to expression in the thyroid, was one to two orders of magnitude less than that of bTG-tk1.Sixty percent of male founders carrying the bTG-tk1α and bTG-tk2 transgenes were fertile but did not transmit the transgene. In contrast, most males from subsequent generations were fertile and transmitted the transgenes at the expected frequency. This difference between founder males and male descendants is also observed with certain constructs in which the HSV1-tk reporter is coupled to other promoters. We attribute the effect to mosaicism among male founders, leading to competition between transgenic and nontransgenic spermatozoa and/or spermatogenic precursor cells and resulting in a lack of fertilization by transgenic sperm that would successfully fertilize eggs in the absence of competition. © 1995 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
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  • 9
    ISSN: 1040-452X
    Keywords: Signal transduction ; Cytokines ; Cancer ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Splice variations in genes coding for the transmembrane FGF receptor (FGFR) result in isoforms that vary in the ectodomain, intracellular juxtamembrane domain, and the intracellular kinase domain. An analysis of biochemical functions of distinct recombinant isoforms expressed in baculoviral-infected insect cells allowed generation of models for function of splice variants in both the ecto- and intracellular domains. A structural model for the ectodomain of the FGFR is proposed as follows. Alternately-spliced immunoglobulin-like disulfide Loop I, which is not required for ligand-binding, is sufficiently interactive with the base FGF binding site formed by Loops II and III to modify ligand affinity and affect interaction of the receptor with heparan sulfate cofactor. The NH2-terminal domain of Loop II, which is highly conserved across all isoforms, exhibits a 19-residue heparin-binding domain which is obligatory for FGF binding. Heparin protects a 30-kDa ligand-binding fragment from proteolysis that is composed of Loop II, the inter-Loop II/III sequence, and the NH2-terminus of Loop III. This suggests that the high-affinity FGF receptor complex is an intimate ternary complex of transmembrane tyrosine kinase, heparan sulfate glycosaminoglycan, and FGF, each of which have interactive binding domains for the other and may contribute to specificity of the FGFR complex. Although Ig Loop II, the inter-Loop II/III sequence, and the NH2-terminus of Loop III with heparan sulfate form the base FGF binding site, mutually exclusive alternate splicing of two exons coding for the COOH-terminal half of Loop III determines which specific members of the FGF ligand family bind with high affinity to the base site.A kinase- and tyrosine phosphorylation site-defective splice variant, FGFR type 2, acts as a dominant-negative suppressor of phosphorylation of specifically tyr-653 in the catalytic domain of the kinase, with less effect on phosphorylation of tyr-766 in the COOH-terminal tail. We propose that phosphorylation of tyr-766, which is required for interaction of phospholipase Cγ1 (PLCγ1) with the receptor, may occur by a cis-intramolecular mechanism within FGFR monomers, while phosphorylation of tyr-653, which is required for phosphorylation of PLCγ1, may occur by a trans-intermolecular mechanism between monomers within kinase homodimers. From the combined results, we propose a model whereby increasing concentrations of FGF may control FGF-mediated signal transduction by heterodimerization of different FGFR monomers. Different monomers arise by regulated combinatorial alternate splicing that alters both the extracellular and intracellular domains. © 1994 Wiley-Liss, Inc.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 8 (1893), S. 563-568 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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