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  • 1990-1994  (3)
  • 1993  (3)
  • 1H and 13C NMR  (1)
  • Astyanax fasciatus (Teleostei) Eye regression  (1)
  • Organic Chemistry
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Materialart
Erscheinungszeitraum
  • 1990-1994  (3)
Jahr
Schlagwörter
  • 1
    Digitale Medien
    Digitale Medien
    Transcription of the opsin gene in degenerate eyes of cave-dwelling Astyanax fasciatus (Teleostei, Characidae) and of its conspecific epigean ancestor during early ontogeny (1993)
    Springer
    Cell & tissue research 273 (1993), S. 183-192 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Opsin ; Retina ; Morphogenesis ; Regressive development ; Eye regression ; Blindness ; In situ hybridization ; Cave fish ; Astyanax fasciatus (Teleostei) Eye regression ; Cave animals
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The early morphogenesis of the degenerate eyes of the Mexican cave fish Astyanax fasciatus and of its conspecific epigean ancestor has been studied comparatively using light- and electron-microscopical techniques; the transcription of the opsin gene has been analysed during early ontogeny in both populations by in situ hybridization. The opsin protein is an integral component of the disk membranes of the photoreceptor cells. In epigean specimens, its expression is correlated with the beginning of outer segment formation on the third day of development. Morphogenesis of the cave fish eye is similar to that of the epigean eye until end of the third day. However, eye growth and morphogenesis of the retina are delayed and sporadic cell death occurs in all retinal layers at the beginning of the second day. Retinal cytodifferentiation breaks off at the point of outer segment formation. Cave specimens are not able to develop regular outer segments at any stage, but the opsin gene is nevertheless expressed in the outer nuclear layer of the developing retina for a limited period of time. On the basis of the comparative morphology and transcriptional studies of epigean and cave specimens, it is suggested that the eye regression of cave fish is primarily the result of mutations of developmental control genes and not of structural genes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00304625
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  • 2
    Digitale Medien
    Digitale Medien
    Compounds with bridgehead nitrogen. Part 72For Part 71, see Ref. 1. - NMR spectra and stereochemistry of 8,9,10,11,11a,11b,12,13-octahydro-7aH-quino [1,2-c][1,3]benzoxazines and perhydropyrido [1,2-c][1,3]benzoxazines. NMR chemical shifts of methylene group protons adjacent to a nitrogen atom (1993)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 31 (1993), S. 505-508 
    Details
    ISSN: 0749-1581
    Schlagwort(e): Octahydro-7aH-quino[1,2-c][1,3]benzoxazines ; Perhydropyrido[1,2-c][1,3]benzoxazines ; 1H and 13C NMR ; Conformation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The positions of conformational equilibria in the four diastereoisomers of 8,9,11,11a,11b,12,13-octahydro-7aH-quino [1,2-c] [1,3] benzoxazines were investigated using 13C and 1H NMR spectroscopy. Comparison of the NMR chemical shifts of these isomers with those in the corresponding isomers of perhydropyrido [1,2-c] [1,3]benzoxazine shows the effect on NMR shifts of fusion of the aromatic ring on to the fully saturated system. The Δδ values are discussed in terms of degree of overlap of the nitrogen lone pair orbitals with the aromatic π-system.
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/mrc.1260310516
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  • 3
    Digitale Medien
    Digitale Medien
    Confusion between dimethyl selenenyl sulfide and dimethyl selenone released by bacteria (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 7 (1993), S. 335-342 
    Details
    ISSN: 0268-2605
    Schlagwort(e): Bioremediation ; biodegradation ; dimethyl selenenyl sulfide ; biomethylation ; pathway ; chemiluminescence ; micro-organism ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Dimethyl selenone [(CH3)2SeO2] has been reported in the literature as a metabolite released by bacteria in contact with selenium metal or selenium salts. In this study, mass spectral, chromatographic, and boiling-point data are presented that show that dimethyl selenone has been confused with dimethyl selenenyl sulfide (CH3SeSCH3). In addition, the headspaces above monocultures of selenium-resistant bacteria were examined using gas chromatography followed by fluorine-induced chemiluminescence detection. A number of alkyl sulfur and selenium species were detected, along with dimethyl selenenyl sulfide. A pathway from oxidized selenium salts to reduced methylated selenides and dimethyl selenenyl sulfide is also presented.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aoc.590070507
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