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  • Cell & Developmental Biology  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Forskolin and the meiosis inducing substance synergistically initiate meiosis in fetal male germ cells (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 34 (1993), S. 47-52 
    Details
    ISSN: 1040-452X
    Keywords: Fetus ; Testis ; Receptors ; MIS ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have shown that Meiosis Inducing Substance (MIS) and forskolin synergistically and dose dependently induce meiosis in germ cells of cultured fetal mouse testes. We used a bioassay which consists of fetal mouse testes and ovaries cultured for 6 days. In this study MIS media are spent culture media from 24 hour cultures of minced adult mouse testes. In the bioassay one gonad of each fetus is cultured either in MIS medium, in control medium with forskolin, or in MIS medium with forskolin. The other gonad serves as the control and is cultured in control medium. After culture the gonads are fixed, squashed, and DNA-stained. In these preparations germ cells and somatic cells can be distinguished, and the number of germ cells in the different stages of meiosis is counted as is the number of somatic cells in mitosis. MIS activity is defined to be present in a medium when meiosis is induced in male germ cells during culture. We found that MIS media as well as forskolin induced meiosis in fetal male germ cells in a dose-dependent manner. In addition, MIS media and forskolin acted synergistically by inducing meiosis. Female germ cells seem to be unaffected by the various culture media. These findings indicate that receptors for stimuli of meiotic initiation may exist in germ cells or neighbouring somatic cells. In addition to induction of meiosis, MIS media and forskolin also dose dependently increase the number of male germ cells compared to controls. This increase is correlated with induction of advanced stages of meiosis: Male germ cells seem to survive better if they are triggered to enter meiosis. Neither MIS media nor forskolin affected the growth of somatic cells. We therefore propose that MIS media has a growth factor activity with a specific effect on meiotic initiation. © 1993 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080340108
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  • 2
    Electronic Resource
    Electronic Resource
    Cumulus cells secrete a meiosi-inducing substance by stimulation with forskolin and dibutyric cyclic adenosine monophosphate (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 39 (1994), S. 17-24 
    Details
    ISSN: 1040-452X
    Keywords: Mouse oocyte ; Meiotic maturation ; Forskolin ; dbcAMP ; Cumulus cells ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The role of the cumulus cells in initiating the resumption of meiosis after exposure to forskolin and dbcAMP was studied in the mouse. The resumption of meiosis was monitored by the percentage of germinal vesicle breakdown (GVBD) and polar body formation (PB). The cumulus-enclosed oocytes (CEO) and denuded oocytes (DO) were cultured with and without hypoxanthine (HX) in the culture medium.Three types of experiments were performed: (1) Effect of forskolin on spontaneous resumption of meiosis, i.e. cultures without HX, and two experiments in which HX is present throughout the culture: (2) Effect of transient exposure to forskolin or dibutyric-cyclic adenosinemonophosphate (dbcAMP) on GVBD prior to continued culture without forskolin or dbcAMP (oocyte priming). (3) Priming of CEO with forskolin for 2 hr, separation of cumulus cells and oocytes, followed by coculture of rejoined cumulus cells and oocytes, or coculture of the cumulus cells and new, unprimed DO.(1) Forskolin inhibited a spontaneous resumption of meiosis in a dose-dependent manner during the first 5 hr of culturing. After 22 hr all controls and CEO resumed meiosis, whereas only half of the DO did.(2) At least 1 hr of priming the CEO with forskolin is needed to induce GVBD and PB formation, but forskolin inhibited the resumption of meiosis when present for 24 hr. Similar results were obtained with a high concentration of dbcAMP.(3) A separation and rejoining of oocytes and cumulus cells after priming induced the resumption of meiosis in a significantly greater number of oocytes than in the control oocytes which were not primed. The GVBD of unstimulated DO also increased significantly when cocultured with cumulus cells from primed CEO. The percentage of GVBD in unprimed DO and in DO isolated from primed CEO was the same.We suggest that within 1-2 hr, forskolin and cAMP stimulate cumulus cells to produce a diffusible meiosis-inducing substance which overcomes HX-inhibition and induces oocyte maturation, including both GVBD and PB formation. The CEO must be primed for more than 2 hr before the resumption of meiosis in DO isolated from such CEO is induced. Oocyte-cumulus connections are crucial as far as initiating the production of a meiosis-inducing substance is concerned. Oocyte-cumulus connections are not needed for transferring this substance to the oocyte. © 1994 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080390104
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  • 3
    Electronic Resource
    Electronic Resource
    The inhibition of DNA-dependent RNA synthesis in yoshida ascites cells by bovine follicular fluid (1975)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 86 (1975), S. 31-35 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Follicular fluid aspirated from large cow follicles inhibits endogenous, DNA-dependent RNA polymerase activity in Yoshida ascites cells. The inhibitory component of follicular fluid is probably a protein and appears to affect specifically the activity of the nucleoplasmic polymerase II.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040860105
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