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  • 1
    ISSN: 1432-041X
    Keywords: Key words engrailed ; Thermobia domestica ; Oncopeltus fasciatus ; Dorsal ridge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Homologues of the Drosophila segment polarity gene engrailed have been cloned from many insect species, as well as other arthropods and non-arthropods. We have cloned partial cDNAs of two engrailed homologues, which we call engrailed-related genes, from the phylogenetically basal insect, Thermobia domestica (Order Thysanura) and possibly as many as four engrailed-related genes from the phylogenetically intermediate insect, Oncopeltus fasciatus (Order Hemiptera). Previous to our findings, only single engrailed-related homologues had been found in phylogenetically intermediate insect species (Tribolium and Schistocerca) and in the crustacean Artemia, while two engrailed-related homologues have been found in more derived orders (Hymenoptera and the engrailed and invected genes of lepidopterans and dipterans). Consequently, we performed a phylogenetic analysis of insect engrailed-related genes to determine whether insects ancestrally had one or two engrailed-related genes. We have found evidence of concerted evolution among engrailed-related paralogues, however, that masks the true phylogenetic history of these genes; the phylogeny may only be decipherable, therefore, by examining the presence or absence of engrailed-specific and invected-specific motifs, which will require cloning the full length cDNAs from more species. In addition, we examined the embryonic expression pattern of the two Thermobia engrailed-related genes; like Drosophila engrailed and invected, they are expressed in very similar patterns, but show one temporal difference in pregnathal segments that correlates with the tentative phylogenetic placement of the genes. Thermobia engrailed-related expression also confirms that the dorsal ridge is an ancient structure in insects.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 51-57 
    ISSN: 0899-0042
    Keywords: molecular mechanic ; guest-host cyclodextrin complexes ; enantiodiscriminating forces ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A molecular mechanics investigation of R- vs. S-phenylethanol, R- vs. S-mandelic acid, R- vs. S-flurbiprofen, and R- vs. S-fenoprofen in their cyclodextrin crystal environments was undertaken. It was found that the dominant force responsible for guesthost complexation is the short-range London force; the enantiodiscriminating forces tend to be very small and are generally, but not always, dominated by long-range electrostatic contributions. Derivatized cyclodextrins are generally more enantiodiscriminating than native cyclodextrins, perhaps due to exterior rather than interior guest-host binding. © 1993 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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