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  • atpB  (2)
  • Cell & Developmental Biology  (1)
  • Euglossini  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Altering the 3′ UTR endonucleolytic cleavage site of a Chlamydomonas chloroplast mRNA affects 3′-end maturation in vitro but not in vivo (1999)
    Springer
    Plant molecular biology 40 (1999), S. 679-686 
    Details
    ISSN: 1573-5028
    Keywords: atpB ; Chlamydomonas reinhardtii ; chloroplast gene expression ; mRNA processing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The 3′ ends of chloroplast mRNAs are produced by the processing of longer precursors. The 3′ ends of most plastid mRNAs are located at, or several nucleotides downstream of, stem-loop structures, which act as 3′-end-processing signals and RNA stability elements. In chloroplasts of the green alga Chlamydomonas reinhardtii, 3′-end maturation of atpB mRNA involves endonucleolytic cleavage of the pre-mRNA at an AU-rich site located about 10 nucleotides downstream of the stem-loop structure. This cleavage is followed by exonucleolytic resection to generate the mature 3′ end. In order to define critical nucleotides of the endonucleolytic cleavage site, we mutated its sequence. Incubation of synthetic atpB pre-RNAs containing these mutations in a chloroplast protein extract resulted in the accumulation of 3′-end-processed products. However, in two cases where the AU-rich sequence of this site was replaced with a GC-rich one, the 3′ end of the stable processing product differed from that of the wild-type product. To examine whether these mutations affected atpB mRNA processing or accumulation in vivo, the endogenous 3′ UTR was replaced with mutated sequences by biolistic transformation of Chlamydomonas chloroplasts. Analysis of the resulting strains revealed that the accumulation of atpB mRNA was approximately equal to that of wild-type cells, and that a wild-type atpB 3′ end was generated. These results imply that Chlamydomonas atpB 3′ processing parallels the situation with other endonucleases such as Escherichia coli RNAse E, where specific sequences are required for correct in vitro processing, but in vivo these mutations can be overcome.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006252201661
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The sequence and structure of the 3′-untranslated regions of chloroplast transcripts are important determinants of mRNA accumulation and stability (1998)
    Springer
    Plant molecular biology 36 (1998), S. 307-314 
    Details
    ISSN: 1573-5028
    Keywords: atpB ; Chlamydomonas reinhardtii ; chloroplast ; inverted repeat ; 3′-untranslated region
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A general characteristic of the 3′-untranslated regions (3′ UTRs) of plastid mRNAs is an inverted repeat (IR) sequence that can fold into a stem-loop structure. These stem-loops are RNA 3′-end processing signals and determinants of mRNA stability, not transcription terminators. Incubation of synthetic RNAs corresponding to the 3′ UTRs of Chlamydomonas chloroplast genes atpB and petD with a chloroplast protein extract resulted in the accumulation of stable processing products. Synthetic RNAs of the petA 3′ UTR and the antisense strand of atpB 3′ UTR were degraded in the extract. To examine 3′ UTR function in vivo, the atpB 3′ UTR was replaced with the 3′ UTR sequences of the Chlamydomonas chloroplast genes petD, petD plus trnR, rbcL, petA and E. coli thrA by biolistic transformation of Chlamydomonas chloroplasts. Each 3′ UTR was inserted in both the sense and antisense orientations. The accumulation of both total atpB mRNA and ATPase β-subunit protein in all transformants was increased compared to a strain in which the atpB 3′ UTR had been deleted. However, the level of discrete atpB transcripts in transformants containing the antisense 3′ UTR sequences was reduced to approximately one-half that of transformants containing the 3′ UTRs in the sense orientation. These results imply that both the nucleotide sequences and the stem-loop structures of the 3′ UTRs are important for transcript 3′-end processing, and for accumulation of the mature mRNAs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005943701253
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  • 3
    Electronic Resource
    Electronic Resource
    Nonfloral sources of chemicals that attract male euglossine bees (Apidae: Euglossini) (1993)
    Springer
    Journal of chemical ecology 19 (1993), S. 3017-3027 
    Details
    ISSN: 1573-1561
    Keywords: Hymenoptera ; Apidae ; Euglossini ; floral fragrance ; fungi ; skatole ; chemical ecology ; orchid ; rotting wood
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract We present chemical analysis of four rotten or fungus-infected logs that attracted fragrance-collecting male euglossine bees. Eight of the 10 volatile compounds detected have never been found in the fragrances of orchids pollinated by male euglossine bees. Nonfloral sources of chemicals such as rotting wood may constitute an important fragrance resource for male bees. Since rotten logs produce large quantities of chemicals over long periods of time, such nonfloral sources might be more important than flowers as a source of certain fragrances for some euglossine bee species. Fragrance collecting in euglossine bees might have evolved originally in relation with rotting wood rather than flowers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00980599
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  • 4
    Electronic Resource
    Electronic Resource
    A pathway of coagulation on endothelial cells (1985)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 28 (1985), S. 253-264 
    Details
    ISSN: 0730-2312
    Keywords: coagulation ; endothelial cell ; thrombosis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Although the endothelial cell is considered antithrombogenic, endothelium has recently been shown to participate in procoagulant reactions. Factor IX bound to specific endothelial cell sites can be activated by the intrinsic and extrinsic pathways of coagulation. Perturbation of endothelium results in induction of tissue factor which promotes factor VIIa-mediated activation of factors IX and X. thus initiating procoagulant events on the endothelial surface. Cell bound factor IXa, in the presence of factor VIII, promotes activation of factor X. The factor Xa formed can interact with endothelial cell factor V/Va, resulting in prothrombin activation. Thrombin then cleaves fibrinogen and a fibrin clot closely associated with the endothelial cell forms. The perturbed endothelial cell thus provides a focus of localized procoagulant events. This model suggests a simple endothelial-cell-dependent mechanism for initiation of coagulation at the site of an injured or pathological vessel.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240280403
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