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  • Cell & Developmental Biology  (3)
  • Ecdysis  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Journal of comparative physiology 168 (1991), S. 697-707 
    ISSN: 1432-1351
    Schlagwort(e): Ecdysis ; Eclosion hormone ; Manduca sexta ; Neuropeptide ; Lepidoptera ; Pupal molt ; Verson's gland
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary 1. Ecdysis, a behavior by which insects shed the old cuticle at the culmination of each molt, is triggered by a unique peptide hormone, eclosion hormone (EH). In pupal Manduca sexta, EH is released into the hemolymph just prior to ecdysis, and circulating hormone is sufficient to elicit this behavior. 2. Removal of the proctodeal nerves in prepupal animals eliminated the appearance of blood-borne EH, but ecdysis behavior occurred on schedule. Therefore, circulating EH is not necessary for the triggering of ecdysis. 3. In contrast, a set of dermal glands failed to show their expected bout of secretion after proctodeal nerve removal. Injection of exogenous EH rescued this secretion. Thus, circulating EH appears necessary for action on peripheral but not central targets. 4. A major reduction in EH immunostaining is seen in the proctodeal nerves just preceding ecdysis; this coincides with a 〉90% reduction in extractable EH from this structure and the appearance of circulating EH. A similar, concomitant reduction was seen in central EH cell processes, suggesting release of peptide within the CNS. 5. Antidromic stimulation of the proctodeal nerve stumps following proctodeal nerve removal triggered precocious ecdysis. This result further supports the conclusion that centrally released EH is sufficient to trigger the motor program.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 33 (1992), S. 119-123 
    ISSN: 1040-452X
    Schlagwort(e): Porcine ; -Amanitin ; Immunoreactivity ; Monoclonal antibody ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie
    Notizen: The appearance and stabilization of a core protein epitope of the snRNP is developmentally regulated during pig embryogenesis. The epitope recognized by the monoclonal antibody Y12 is present in the germinal vesicle of mature ooocytes and interphase nuclei of late 4-cell stage (24 to 30 hours post cleavage to the 4-cell stage) to blastocyst stage embryos. There was no antibody iocalization within pronuclei, or nuclei of 2-cell or early 4-cell stage embryos. Zygotes or 2-cell stage embryos cultured in the presence of α-amanitin to the late 4-cell stage showed no immunoreactivity, whereas control embryos had immunoreactivity. Thus antibody localization was correlated with RNA synthesis and RNA processing that begins by 24 hours post cleavage to the 4-cell stage. A final experiment showed no detectable immunoreactivity in 16-cell stage nuclei that had been transferred to enucleated activated meiotic metaphase II oocytes. Since immunoreactivity is associated with active RNA synthesis and RNA processing, it suggests that the 16-cell stage nucleus, which is RNA synthetically active, does not process RNA after nuclear transfer to an enucleated activated meiotic metaphase II oocyte. © 1992 Wiley-Liss, Inc.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 41 (1995), S. 70-75 
    ISSN: 1040-452X
    Schlagwort(e): Pig ; Parthenogenesis ; Cycloheximide ; Puromycin ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie
    Notizen: This study was designed to evaluate the effects of cycloheximide and puromycin on activation and protein synthesis of porcine oocytes. When matured oocytes were electrostimulated, then cultured in the presence of cycloheximide (5 μ/ml) for 6 or 24 hr, 92% of oocytes were activated as indicated by pronuclear formation, vs. 2.8% for untreated oocytes, 5.3% for oocytes not electrostimulated but cultured with cycloheximide, and 60.0% for those only electrostimulated. When cultured with L-[35S]methionine in the presence of cycloheximide, puromycin (100 μg/ml), or no protein synthesis inhibitor for 24 hr, oocytes had mean radiolabeled incorporation rates of 36.5, 2.21, and 32.0 fmol/4 hr/oocyte, respectively. Thus, cycloheximide had little effect on protein synthesis after 24 hr of culture. A 1D-SDS PAGE showed that oocytes cultured with puromycin or cycloheximide are not activated, while electrostimulated oocytes are activated, as characterized by the conversion of a 25-kDa polypeptide to a 22-kDa polypeptide. The radiolabeling experiment was repeated, except that oocytes were cultured for 4 or 24 hr. At 4 hr, mean incorporation rates were lower in the cycloheximide group (2.34 fmol/4 hr/oocyte), but similar in the puromycin (15.7 fmol/4 hr/oocyte) and control groups (18.9 fmol/4 hr/oocyte). At 24 hr, the puromycin group (5.73 fmol/4 hr/oocyte) had a lower rate of incorporation, while the cycloheximide (22.6 fmol/4 hr/oocyte) and control (26.0 fmol/4 hr/oocyte) groups were similar. Cycloheximide was more effective earlier during culture, while puromycin was more effective later. When combined with ES, puromycin did have a higher rate (P = 0.10) of activation (87.8%) than with electrostimulation alone (73.0%). A final experiment evaluated the development to blastocyst after transfer to a ligated oviduct. Cycloheximide treatment in conjunction with an electric pulse did not increase the rate of compact morula or blastocyst formation. In conclusion, puromycin and cycloheximide have differential effects on protein synthesis, and although cycloheximide alone will not induce activation in porcine oocytes, it is very effective in generating activated oocytes in combination with electrostimulation. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Gamete Research 22 (1989), S. 233-247 
    ISSN: 0148-7280
    Schlagwort(e): chimera ; transgenics ; embryos ; ES cells ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie
    Notizen: The preimplantation embryo is highly resilient to experimental manipulations. A specific manipulation that has revealed many clues to the developmental process is chimera production. Chimeras have been used to describe the importance of developmental characteristics of embryonic cells and how these characteristics are involved with developmental fate. These characteristics have been monopolized in the production of interspecific chimeras and the production of transgenic animals. This review attempts to discuss the major factors affecting preimplantation mammalian embryo chimera production.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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