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  • 1
    Electronic Resource
    Electronic Resource
    A cladistic phylogeny of the genus Littorina (Gastropoda): implications for evolution of reproductive strategies and for classification (1990)
    Springer
    Hydrobiologia 193 (1990), S. 1-19 
    Details
    ISSN: 1573-5117
    Keywords: biogeography ; Atlantic ; Pacific ; reproductive strategy ; larval development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Gross anatomical characters of all 18 species of Littorina are used to construct a phylogenetic hypothesis for the genus, by the method of cladistic analysis. The resulting cladogram suggests that of the four subgenera of Littorina, one (Littorina) is paraphyletic. It is uncertain whether the genus Mainwaringia should be included in Littorina. It is shown that the non-planktotrophic Littorina species in the northern Atlantic comprise a monophyletic group, with the sister-species L. kurila and/or L. subrotundata in the northern Pacific. Invasion of the Atlantic by a minimum of two Pacific species, across the Arctic migration route established during the late Cenozoic, is sufficient to account for the modern distribution of the subgenera Littorina and Neritrema. The importance of the cladogram as a basis for hypotheses of adaptation is illustrated by a discussion of spawn and development in Littorina.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00028062
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Shell microstructure and mineralogy of the Littorinidae: ecological and evolutionary significance (1990)
    Springer
    Hydrobiologia 193 (1990), S. 199-215 
    Details
    ISSN: 1573-5117
    Keywords: shell dissolution ; calcite ; aragonite ; shell structure ; latitudinal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An examination of the shell microstructure and mineralogy of species from 30 of the 32 genera and subgenera of the gastropod family Littorinidae shows that most species have a shell consisting of layers of aragonitic crossed-lamellar structure, with minor variations in some taxa. However, Pellilitorina, Risellopsis and most species of Littorina have partly or entirely calcitic shells. In Pellilitorina the shell is made entirely of calcitic crossed-foliated structure, while in the other two genera there is only an outer calcitic layer of irregular-prismatic structure. A cladistic analysis shows that the calcitic layers have been independently evolved in at least three clades. The calcite is found only in the outermost layers of the shell and in species inhabiting cooler waters of both northern and southern hemispheres. Calcium carbonate is more soluble in cold than warm water and, of the two polymorphs, calcite is about 35% less soluble than aragonite. We suggest that calcitic shell layers are an adaptation of high latitude littorinids to resist shell dissolution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00028077
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Calmodulin discriminates between the two enantiomers of the receptor-operated calcium channel blocker sk&f 96365: A study using 1H-NMR and chiral HPLC (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 229-232 
    Details
    ISSN: 0899-0042
    Keywords: receptor-operated calcium channel antagonist ; 1H NMR ; chiral HPLC ; calmodulin ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1H nuclear magnetic resonance at 360 MHz shows that SK&F 96365 (1-{β-[3-(p-methoxyphenyl)-propyloxy]-p-methoxyphenethyl}-1H- imidazole hydrochloride), an antagonist of mammalian receptor-operated calcium channels, interacts with the calcium-binding regulatory protein calmodulin (CaM). This may be inferred by a number of chemical shift changes in the spectrum of the calcium-saturated protein induced by addition of the compound. Moreover, two well-resolved singlets corresponding to the 2-proton of the SK&F 96365 imidazolium moiety are observed in the spectrum over a wide range of protein:compound ratios. Separation of rac SK&F 96365 into its two enantiomers by high-performance liquid chromatography on a cellulose tris (4-methylbenzoate) column enabled us to show that the doubling of this NMR signal in the presence of CaM is due to a propensity of the protein to distinguish between the two optical isomers of the compound.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020407
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    Paper (German National Licenses)
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