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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Development genes and evolution 184 (1978), S. 143-153 
    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
    Springer
    Development genes and evolution 187 (1979), S. 283-305 
    ISSN: 1432-041X
    Keywords: Inhibitors ; Insect embryogenesis ; Oogenesis ; Permeabilisation ; Two-dimensional gel electrophoresis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Embryos of the chironomid midgeSmittia spec. were permeabilized with sodium hypochlorite and octane. Uptake of labeled uridine and amino acids suggested that these compounds are actively transported across the plasma membrane. Before blastoderm formation, uridine was incorporated at low levels into nuclear DNA and mitochondrial RNA. After blastoderm formation, uridine was incorporated rapidly, mostly into cytoplasmic RNA including both ribosomal RNA precursors and poly(A)-containing RNA. Protein synthesis was observed throughout early embryogenesis. By measuring incorporation of labeled amino acids and internal amino acid pool sizes, we found that the rate of protein synthesis increased with development. Experiments with inhibitors of transcription indicated that proteins synthesized before blastoderm formation were translated from maternal mRNA. During blastoderm stages, embryonic mRNAs seemed to replace maternal mRNAs. Proteins synthesized during short incubation periods in vivo were separated by two-dimensional gel electrophoresis. After blastoderm formation, several new proteins were found that could not be detected at earlier stages.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-041X
    Keywords: Drosophila ; Dorsalizing mutant ; Phenotypic rescue ; Poly(A)+ RNA ; Cytoplasm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary spätzle (spz), a maternal effect gene of Drosophila, is involved in the establishment of the dorso-ventral axis during embryogenesis. Eggs from females lacking the spz gene product develop into completely dorsalized embryos, i.e. the ventral and lateral pattern elements fail to develop. Upon injection of either cytoplasm or poly(A)+ RNA from early wild-type embryos, spz embryos develop lateral pattern elements represented by Filzkörper and in the case of injected cytoplasm additional ventral pattern elements represented by ventral setae. Wild-type cytoplasm retains the rescuing activity longer than the poly(A)+ RNA fraction does, and cytoplasm is always more effective in provoking the rescue than poly(A)+ RNA. Mosaic females containing spz germ cells surrounded by spz + tissues were generated by pole cell transplantations; a mutant genotype in the germ cells is sufficient to produce all aspects of the spz mutant phenotype, suggesting that the maternal source of spz gene product is the germ line.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Development genes and evolution 187 (1979), S. 179-193 
    ISSN: 1432-041X
    Keywords: Insect embryogenesis ; Poly(A)-containing RNA ; maternal RNA ; RNP-particles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Eggs of the chironomid midgeSmittia spec. were shown to contain maternal rRNA, tRNA and poly(A)-containing RNA. The ribonucleoprotein spectrum consisted of monosomes, ribosomal subunits, and subribosomal particles, whereas polysomes could be detected only in small amounts. Poly(A)-containing RNA was found in different regions of the RNP spectrum, mainly between 15 S and 60 S. After labelling maternal RNA by feeding tritiated uridine to the larvae, the radioactivity associated with poly(A)-containing RNA accounted for about 4% of the label in the total RNA extracted from newly deposited eggs. About half of the radioactivity in the poly(A)-containing RNA was lost between egg deposition and an advanced blastoderm stage. The loss was accompanied by both a decrease in the size of the poly(A)-containing RNA molecules and a shift of poly(A)-containing RNP particles to less dense regions in sucrose gradients. Comparison with poly(A)-containing RNA synthesized by the embryo indicates that the reduction in size of maternal poly(A)-containing RNA is not artifactual but reflects its degradation after the formation of blastoderm.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-041X
    Keywords: Key words Transcription factor ; Zinc finger ; Molecular evolution ; Development ; spalt gene family
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  We report the full coding sequence of a new Drosophila gene, spalt-related, which is homologous and adjacent to the region-specific homeotic gene, spalt. Both genes have three widely spaced sets of C2H2 zinc finger motifs, but spalt-related encodes a fourth pair of C-terminal fingers resembling the Xenopus homologue, Xsal-1. The degrees of sequence divergence among all three members of this family are comparable, suggesting that the Drosophila genes originated from an ancient gene duplication. The spalt-related gene is expressed with quantitative variations from mid-embryogenesis (8–12 h) to the adult stage, but not in ovaries or early embryos. Expression is localized to limited parts of the body, including specific cell populations in the nervous system. In the wing disc, spalt and spalt-related are expressed in indistinguishable domains; in the nervous system and some other organs the expression patterns extensively overlap but are not identical, indicating that the genes have partially diverged in terms of developmental regulation. A characteristic central set of zinc fingers specifically binds to an A/T-rich consensus sequence, defining some DNA binding properties of this ancient family of nuclear factors.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Development genes and evolution 188 (1980), S. 225-233 
    ISSN: 1432-041X
    Keywords: Insect embryogenesis ; Actin synthesis ; “Masked” mRNP-particles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Actin synthesis was observed in early embryos of the chironomid midgeSmittia spec. The criteria used to identify newly synthesized actin include comigration with purified actin in two-dimensional gel electrophoresis, and peptide mapping after limited proteolysis. Actin was also identified after in vitro translation of RNA or salt washed RNP-particles isolated from newly deposited eggs. While intact RNP-particles stimulated protein synthesis only poorly, the rate of synthesis increased considerably after partial or complete removal of proteins from RNP-particles. Actin was synthesized both during advanced stages of oogenesis and during early embryogenesis. In embryos during intravitelline cleavage actin synthesis was insensitive to inhibitors of transcription (actinomycin D, α-amanitin). Actin was found everywhere along the longitudinal axis of the embryo using a procedure which allowed simultaneous sectioning of a large number of embryos.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-041X
    Keywords: Drosophila embryo ; Homeotic genes ; Fork head gene ; Gut development ; Enhancer detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The homeotic gene fork head (fkh) of Drosophila melanogaster promotes terminal as opposed to segmental development in the ectodermal parts of the gut. Molecular analysis revealed that fkh expression is not restricted to the ectodermal parts of the gut, but is detectable in a variety of other tissues. Therefore, the phenotype of fkh mutant embryos was re-examined using molecular probes as tissue specific markers. With the exception of the nervous system, which was not studied, phenotypic effects were found in all tissues expressing fkh protein in the wild-type. Particularly, these tissues include all components of the gut in the Drosophila embryo: the foregut and hindgut, the midgut and the yolk nuclei. The defects observed in the gut of fkh mutant embryos are primordium specific.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Development genes and evolution 207 (1997), S. 186-193 
    ISSN: 1432-041X
    Keywords: Key words Conserved protein domains ; Developmental expression pattern ; Drosophila embryo ; Krüppel ; Muscle development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Krüppel (Kr), a member of the gap class of Drosophila segmentation genes, encodes a zinc finger-type transcription factor. After blastoderm formation, Kr is expressed in various spatially and temporally restricted patterns of the developing embryo, including a subset of muscle precursors. By virtue of Krüppel in vitro binding sites, we identified a putative Kr target gene, termed KrT95D. It encodes a novel protein which contains evolutionarily conserved regions. KrT95D is expressed in spatially restricted patterns throughout embryogenesis. Kr and KrT95D expression overlap in several locations including muscle precursor cells, the tip cell of the Malpighian tubules and the ventral midline cells of the central nervous system. Results from the analysis of the KrT95D expression pattern in Kr loss-of-fuction and Kr gain-of-function embryos suggest that Kr activity is not essential for KrT95D expression in most locations of the embryo, except in the muscle precursors VO5.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Irregular facets (If) is a dominant gain-of-function allele of the Drosophila segmentation gene Krüppel (Kr) that interferes with eye development. In a search for genes that interact with Kr activity, we recently performed a systematic genetic screen to identify dominant enhancers and suppressors of the If eye phenotype that are located on the third chromosome. Here we describe locations and candidate genes of the second chromosome that act as dominant modifiers of ectopic Kr activity during eye development. The collection of more than 40 modifiers of Kr activity located on the second and third chromosomes, from which a total of 16 genes were identified, includes genes encoding transcription factors and components of signal transduction pathways that may regulate or be regulated by Kr activity. We also identified genes coding for more general cellular factors that could interfere with the intracellular transport or the half-life of the Kr protein. The data demonstrate that the If mutation provides a means to screen the Drosophila genome for functional components of developmental pathways that depend on or can be modified by Kr activity. Owing to the bias of the screening system applied, these modifier genes will be expressed and are likely to be required during Drosophila wild-type eye development.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The Drosophila melanogaster genome contains about 100 copies of the B104 transposable element, which is strongly expressed during embryogenesis. Here we show that B104 expression is restricted to the esophageal and amnioproctodeal regions of the embryo and to the developing mesoderm. Mesoderm-specific B104 expression requires the activity of the mesoderm-determining factors twist and snail. Virtually the same expression patterns were observed in Drosophila yakuba, a species that a separated from D. melanogaster by some 15 million years of evolution. We show that B104 expression is directed by internal sequences of the retrotransposon that are capable of acting as a cis-acting regulatory element in front of a heterologous Drosophila promoter. Our findings suggest that retrotransposon insertions can affect the expression patterns of endogenous genes by adding and distributing specific cis-acting control elements throughout the host genome. We therefore propose that transposable elements in addition to reducing the fitness of their hosts may also provide a rich pool of cis-acting sequences that contribute to the long-term evolutionary potential of the population in a beneficial manner.
    Type of Medium: Electronic Resource
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