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  • 1
    Electronic Resource
    Electronic Resource
    Culture media for mouse oocyte maturation affect subsequent embryonic development (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 25 (1990), S. 164-171 
    Details
    ISSN: 1040-452X
    Keywords: Oocyte maturation ; Developmental capacity ; Culture medium ; Fertilization ; Mouse ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: These experiments were done to determine whether the culture medium used for the spontaneous maturation of mouse oocytes can affect the subsequent capacity of the ova to become fertilized and complete preimplantation development in vitro and development to live young. Oocytes obtained from antral follicles of gonadotropin-primed immature mice underwent spontaneous maturation in control medium, i.e. Eagle's Minimum Essential Medium (MEM) supplemented with 5% fetal bovine serum, or in one of eight different media which were also supplemented with serum. All of the ova were fertilized in Whitten's medium and were assessed for cleavage to the 2-cell stage and for further preimplantation development to blastocysts during culture in Whitten's medium. Three of the eight media used for oocyte maturation improved the capacity of the ova to develop to the blastocyst stage when compared with the control: Waymouth MB 752/1, MEM with non-essential amino acids, and MEM Alpha; Waymouth medium promoted the highest frequency of development of ova to the blastocyst stage. Moreover, the blastocysts derived from oocytes that matured in Waymouth medium contained more cells than blastocysts derived from oocytes that matured in control medium. Although BGJb medium promoted the cleavage of eggs to the 2-cell stage when present during oocyte maturation, it had a detrimental effect on their subsequent preimplantation developmental capacity. Following transfer to foster mothers, more 2-cell stage embryos developed to live young after oocyte maturation in Waymouth medium (21%) than in control medium (13%). It is concluded that the medium used for oocyte maturation in vitro can affect processes involved in the subsequent development of the eggs and that, of the media tested, Waymouth MB 752/1 promoted the highest capacity for embryo development of maturing mouse oocytes.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080250209
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  • 2
    Electronic Resource
    Electronic Resource
    Comparison between transport and degradation of leucine and glutamine by peripheral human lymphocytes exposed to concanavalin A (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 143 (1990), S. 94-99 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Transport and pathways of leucine and glutamine degradation were evaluated in resting human peripheral lymphocytes and compared with the changes induced by concanavalin A (ConA). Cells were incubated with [1-14C]leucine (0.15 mM), [U-14C]leucine (0.15 mM), or [U-14C]glutamine (0.4 mM) after culture with or without 2, 5, 7, or 10 μg/ml ConA for 2, 18, or 24 hours, respectively. Initial rates of transport of leucine and glutamine were augmented 2.7-fold and threefold by the mitogen. Leucine transamination, irreversible oxidation, and catabolism beyond isovaleryl-CoA were increased by 90%, 20%, and 60%, respectively. Glu-tamine utilization increased threefold; accumulation of glutamate, aspartate, and ammonia increased by 700%, 50%, and 100%, respectively, and 14CO2 production by about 400% in response to ConA. The results indicate that ConA stimulates to about the same extent transport of leucine and glutamine into lymphocytes. Glutamine is mainly channeled into catabolic pathways, while leucine remains largely preserved. It is suggested that these metabolic changes provide more leucine for incorporation into protein and more N- and C-atoms required for the synthesis of macromolecules and energy from glutamine.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041430112
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  • 3
    Electronic Resource
    Electronic Resource
    Evidence for involvement of a nuclear envelope-associated RNA helicase activity in nucleocytoplasmic RNA transport (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 145 (1990), S. 136-146 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: It seems well established that translocation of at least some mRNAs through the nuclear pore is (1) an energy-dependent process, and (2) dependent on the presence of the poly(A) segment attached to most mRNA species. We describe that RNA helicase (RNA duplex unwindase) activity is present in a nuclear envelope (NE) preparation, which also appears to be involved in nucleocytoplasmic RNA transport. This activity unwinds RNA : RNA hybrids. The helicase has a pH optimum of 7.5 and a temperature optimum of 30°C. Applying the sealed NE vesicle system, it was shown that duplex RNA species are readily released from the vesicles in an unidirectional manner, in contrast to single-stranded RNA, which is much slower transported into the extravesicular space. Attachment of a poly(A) segment to the RNA duplex additionally increases the efflux rate of this RNA. Efflux of duplex RNA but not efflux of single-stranded RNA was strongly inhibited by formycin B 5′-triphosphate. Our results suggest that, besides poly(A), duplex structures, if present in a given RNA, modulate and control the export of RNA.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041450119
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  • 4
    Electronic Resource
    Electronic Resource
    Characterization of glutamine transport into resting and concanavalin A-stimulated peripheral human lymphocytes (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 145 (1990), S. 155-161 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Characteristics of glutamine transport, its substrate specificity, and its pattern of competitive and non-competitive inhibition in response to amino acid analogues were determined in peripheral human lymphocytes, incubated with or without concanavalin A (Con A). Maximum capacity of transport (Vmax) at 37°C and 136.9 mM Na+ was 30 pmol/106 cells/30 seconds, while the apparent Km was 142 μM. In cells exposed to 10 mM histidine, asparagine, serine, or leucine transport of glutamine declined to 28%, 15%, 17%, and 21%, respectively, of the rates in controls. Inhibition by histidine (Ki = 0.58 mM) and serine (Ki = 0.25 mM) was competitive, by leucine was non-competitive (Ki = 0.64), while α-methylamino-isobutyric acid and 2-amino carboxy-bicyclo (2.2.1)-heptane had no effect. In cells cultured for 24 hours with or without 10 μg/ml Con A, the apparent Km was 70 μM vs. 89 μM and Vmax 73 vs. 26 pmol/106 cells/30 seconds. Sodium depletion (9.0 mM NaCl) greatly diminished glutamine transport in resting and stimulated cells. Inhibition of glutamine transport by serine was sodium sensitive, while inhibition by histdine and asparagine was not. Serine had no competitive effect in sodium-depleted media. The data demonstrate what appear to be two carrier systems for glutamine, sodium sensitive and sodium insensitive. It is suggested that glutamine transport into lymphocytes occurs via processes similar to System N and System ASC described in other cells, with System ASC as the sodium-sensitive component. Con A augments the capacity rather than the affinity of glutamine transporting systems.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041450121
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  • 5
    Electronic Resource
    Electronic Resource
    Human aortic endothelial cells express the type I but not the type II receptor for interleukin-1 (IL-1) (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 153 (1992), S. 583-588 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Endothelial cells (EC) are very responsive to the proinflammatory cytokine inter-leukin-1 (IL-1). EC are induced by IL-1 to secrete chemotactic factors and to increase expression of cell surface adhesion molecules leading to increased leukocyte adhesion. Activated EC turther contribute to the inflammatory response by secreting additional cytokines. IL-1 interacts with EC through high-affinity cell-surface receptors. However, the low number of receptors present on EC has made characterization difficult. Further, recent evidence has suggested diversity in the responses of EC from different regions of the vascular system. Interested in the effect of IL-1 on early atherosclerotic lesion formation, we have characterized the IL-1 receptors on human aortic endothelial cells (HAEC). Using a direct binding assay, we found that HAEC have 1,000-3,000 IL-1 receptors per cell and bind IL-1α with a Kd of 3.5 × 10-10 M. We found that a monoclonal antibody specific for the type I receptor completely blocks IL-1α binding. The blocking antibody also completely inhibits the IL-1 induced increase in intracellular adhesion molecule 1 (ICAM-1) expression by HAEC. Using solution hybridization and ribonuclease protection with an antisense probe, a sensitive method for detection of low abundance mRNA species we found that HAEC as well as human umbilical vein EC (HUVEC) have significant levels of mRNA for the type I IL-1 receptor. To test whether HAEC might also contain transcripts for the type II IL-1 receptor, we compared levels of mRNAs by polymerase chain reaction (PCR) amplification of cDNAs reverse-transcribed from total RNA. We found only transcripts for the type I receptor and not the type II receptor in HAEC. Based on this data, we conclude that aortic endothelial cells respond to IL-1 through the type I receptor. © 1992 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041530320
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  • 6
    Electronic Resource
    Electronic Resource
    RNA as a catalyst: Natural and designed ribozymes (1993)
    New York, NY : Wiley-Blackwell
    BioEssays 15 (1993), S. 299-307 
    Details
    ISSN: 0265-9247
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: RNA can catalyse chemical reactions through its ability to fold into complex three-dimensional structures and to specifically bind small molecules and divalent metal ions. The 2′-hydroxyl groups of the ribose moieties contribute to this exceptional reactivity of RNA, compared to DNA. RNA is not only able to catalyse phosphate ester transfer reactions in ribonucleic acids, but can also show aminoacyl esterase activity, and is probably able to promote peptide bond formation. Bearing its potential for functioning both as a genome and as a gene product, RNA is suitable for in vitro evolution experiments enabling the selection of molecules with new properties. The growing repertoire of RNA catalysed reactions will establish RNA as a primordial molecule in the evolution of life.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bies.950150503
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