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  • 1
    ISSN: 1432-041X
    Keywords: Insect embryogenesis ; 3H-uridine precursor conversion ; Polyadenylated RNA ; Maternal RNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung In der Oogenese und frühen Embryogenese markierte Nukleinsäuren wurden aus Eiern der ZikadeEuscelis plebejus isoliert. Poly(A)-haltige RNS wird in frühen Oogenesestadien in die Oocyte eingebaut. Im frisch abgelegten Ei beträgt ihr Anteil am RNS-Gehalt etwa 2,7%. Im Molekulargewicht ist diese Fraktion (15–32 S) deutlich verschieden von poly(A)-haltiger RNS aus dem embryonalen Markierungszeitraum zwischen früher Furchung und Vorkeimanlagenstadium (4–20 S). Am vorderen Eiende injiziertes3H-Uridin war innerhalb von 3 h gleichmäßig über den Eiraum verteilt. Als3H-Uridin im frühen Furchungsstadium injizierte Markierung fand sich in späteren Stadien (nach 10–10 h) in hohem Umfang in DNS eingebaut (25–35%); markierte RNS konnte erst im zellulären Blastodermstadium nachgewiesen werden. Bei getrennter Aufarbeitung von Dotter-Endoplasma und Blastodermzellen war nur in den letzteren eine embryonale RNS-Synthese erkennbar. Von der im Embryo markierten RNS lagen im frühen Blastodermstadium etwa 10% als poly(A)-haltige RNS vor, im frühen Keimanlagenstadium nur etwa 3%. Anteriore und posteriore Eihälften im frühen Keimanlagenstadium zeigten keine Unterschiede der Molekulargewichte ihrer poly(A)-haltigen RNS.
    Notes: Summary RNA labelled during oogenesis or early embryogenesis was isolated from eggs of the leaf hopperEuscelis plebejus. The polyadenylated RNA fraction deposited during early oogenesis accounted for approximately 2.7% of the total RNA content of the newly laid egg. This fraction differed significantly in molecular weight (15–32 S) from poly(A)-containing RNA synthesised between early cleavage and early germ anlage stages (4–20S). Locally injected3H-uridine spread through the egg within approximately 3 h. A considerable fraction (25–35%) of label injected as3H-uridine during early cleavage was recovered in DNA at subsequent stages (10–20 h later); labelled RNA was not found prior to the cellular blastoderm stage. When the yolk-endoplasm was separated from the blastoderm cells, only the latter contained demonstrable amounts of RNA synthesised by the embryo. Of the precursor incorporated into embryonic RNA, approximately 10% was found in the polyadenylated fraction at the early blastoderm stage, but only 3% at the early germ anlage stage. No differences in size distribution of polyadenylated RNA were evident between anterior and posterior halves of the early germ anlage stage.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    BioEssays 13 (1991), S. 343-346 
    ISSN: 0265-9247
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Insect endoparasitoids are able to circumvent the defense reactions of their habitual hosts. In a hymenopteran wasp species, virus-like particles, found on the egg surface are responsible for the protection against the encapsulation reaction of the host caterpillar. Some of the particle proteins are structurally and probably functionally related to host protein(s). Biological properties of some of the host proteins suggest that they might be involved in the insect defense reaction.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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