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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)

Langecker, Thomas G. ; Schmale, Hartwig ; Wilkens, Horst

Springer

Cell & tissue research 273 (1993), S. 183-192

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ISSN: 1432-0878

Keywords: Opsin ; Retina ; Morphogenesis ; Regressive development ; Eye regression ; Blindness ; In situ hybridization ; Cave fish ; Astyanax fasciatus (Teleostei) Eye regression ; Cave animals

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: 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.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00304625

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Confusion between dimethyl selenenyl sulfide and dimethyl selenone released by bacteria (1993)

Chasteen, Thomas G

New York, NY [u.a.] : Wiley-Blackwell

Applied Organometallic Chemistry 7 (1993), S. 335-342

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ISSN: 0268-2605

Keywords: Bioremediation ; biodegradation ; dimethyl selenenyl sulfide ; biomethylation ; pathway ; chemiluminescence ; micro-organism ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: 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.

Additional Material: 2 Tab.