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  • Cleavage  (2)
  • intersex  (2)
  • Imposex  (1)
  • Nucella  (1)
  • reproductive failure
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  • 1
    Digitale Medien
    Digitale Medien
    The ultrastructure of the yolk nucleus during early cleavage of Nassarius reticulatus L. (Gastropoda, Prosobranchia) (1974)
    Springer
    Cell & tissue research 153 (1974), S. 79-88 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Yolk nuclei ; Nassarius reticulatus ; Cleavage ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Dotterkerne kommen in allen Blastomeren des 4- bis 16-Zellstadiums von Nassarius vor. Sie haben überwiegend kugelige Gestalt und liegen kernnah zwischen Kern und apikalem Plasmalemm. Feinstrukturell sind sie erstaunlicherweise nicht einheitlich aufgebaut, sondern treten in zwei Typen auf: Typ I besteht aus einer relativ kompakt erscheinenden kugeligen Ansammlung von Mitochondrien. Die Mitochondrien liegen in einer dichten, teils granulären, teils fibrillären intermitochondrialen Substanz eingebettet. Typ II besteht aus einer ebenfalls kugeligen Ansammlung vieler kleiner radiär angeordneter Golgi-Stapel, welche in der gleichen dichten, teils granulären, teils fibrillären Substanz liegen wie die Mitochondrien von Typ I. Die Funktion beider Typen von Dotterkernen wird diskutiert. Sicherlich haben sie nichts mehr mit der Dottersynthese zu tun wie möglicherweise die Dotterkerne der Oocyten, doch gibt es bisher auch keine Anzeichen dafür, daß sie bevorzugt am Dotter- oder Lipidabbau beteiligt sind.
    Notizen: Summary In all blastomeres of Nassarius from 4- to 16-cell stage yolk nuclei occur. Most of them are spherical bodies, lying juxtanuclearly between the nucleus and the apical plasmalemma. Strangely they are not ultrastructurally uniform but fall into two categories (Fig. 5): Type I is a massive spherical accumulation of mitochondria embedded in a dense intermitochondrial substance, which appears to contain both granules and filaments. Type II is a ball of radially arranged small Golgi stacks clustered around a centre of Golgi vesicles and other organelles embedded in a ground cytoplasm structurally similar to the intermitochondrial substance of type I. The function of both types of yolk nuclei is unknown. These segmentation yolk nuclei have nothing to do with yolk synthesis any more. On the other hand there are no indications that yolk nuclei occurrence is correlated with the break-down of yolk because neither lipid droplets nor protein yolk granules are observed in or beside the yolk nuclei.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00225447
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Cell differentiation during early development of Nassarius reticulatus L. (Gastropoda, prosobranchia) (1976)
    Springer
    Cell & tissue research 168 (1976), S. 361-371 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Nucleolar differentiation ; Nassarius reticulatus ; Cleavage ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In Nassarius reticulatus the nuclei and nucleoli undergo important morphological changes from the zygote to the 16-cell stage. In the zygote and in the trefoil (2-cell) and 4-cell stage, several agranular, fibrillar nucleolus-like bodies 1 μm diameter are present in the interphase nucleus. Granular nucleoli first appear at the 8-cell stage. These nucleoli have fibrillar and granular regions. The granular regions are made up predominantly of ribosome-like osmiophilic granules. From the 16 and 32-cell stage onwards, the one or two spherical nucleoli of each nucleus measure 2.5 μm in diameter and show a concentric organization with a very dense central region surrounded by a broad peripheral zone containing numerous granules, possibly of ribonucleoprotein. At the same time the number of ribosome-like particles increase in the karyoplasm and that of ribosomes in the cytoplasm. These findings are surprising because in eggs with radial cleavage, which have been subjected to more detailed analysis, the first granular nucleoli appear after the end of the cleavage, at the blastula or gastrula stage. The early appearance of granular nucleoli which seem to be characteristic of several eggs with spiral cleavage is discussed in connection with biochemical data on RNA-synthesis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00215313
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Comparison of imposex response in three Prosobranch species (1995)
    Springer
    Hydrobiologia 309 (1995), S. 29-35 
    Details
    ISSN: 1573-5117
    Schlagwort(e): imposex ; gastropod ; TBT ; Nucella ; Ocenebra ; Hinia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A comparative study of the three gastropod species Nucella lapillus (L.), Ocenebra erinacea (L.) and Hinia (Nassarius) reticulata (L.) reveals that Nucella is the most TBT sensitive species while Hinia is the least sensitive. Of the two imposex indices VDSI and RPSI, good interspecies correlations were obtained only for VDSI. The three species can be considered as complementary not only in terms of their ecology but also for their levels of sensitivity. Indeed, Nucella and Ocenebra are useful test species at TBT concentrations below 2 ng Sn 1−1 while Hinia is the more appropriate species at higher TBT levels. For the first time, two sterilised Hinia females are recorded. This sterilization does not seem to be due to proliferation of vas deferens tissue in the vaginal opening and further investigation is needed to find intermediary VDS stages between stage 4+ and sterilization. Studies using Nucella show that the use of narcotization in imposex analysis leads to an underestimation of RPSI compared with non-narcotization methods. Indeed, narcotization straightens the penis and increases its length when compared with non-narcotized animals, but this increase is proportionally higher in males than in females.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00014469
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Imposex in Nucella lapillus and intersex in Littorina littorea: interspecific comparison of two TBT-induced effects and their geographical uniformity (1998)
    Springer
    Hydrobiologia 378 (1998), S. 199-213 
    Details
    ISSN: 1573-5117
    Schlagwort(e): Nucella lapillus ; Littorina littorea ; imposex ; intersex ; TBT effect monitoring ; geographical differences
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Two different tributyltin (TBT)-induced virilisation phenomena in prosobranch snails – intersex in Littorina littorea and imposex in Nucella lapillus – are compared in order to facilitate their simultaneous use in geographical large scale effect monitoring surveys. Imposex in dogwhelks is a more sensitive biomarker and should be used in areas that are only slightly or moderately contaminated with TBT (ambient TBT concentrations 〈 2.0 ng as Sn l-1). The assessment of intersex intensities in periwinkle populations has considerable advantages in areas with higher TBT concentrations and should be used also wherever dogwhelks are absent irrespective of the TBT exposure level. The intersex index (ISI) and vas deferens sequence (VDS) index are proposed as the most suited parameters for effect monitoring purposes. The geographical uniformity of intersex and imposex is analysed and proven for the coasts of Ireland, France, and Germany. A relative loss of TBT sensitivity in females can be found, but to a varying extent in both species. The implications of this result for biological TBT effect monitoring programmes are discussed in light of the fact that intersex and imposex have both been found to be irreversible. Because it is the objective of these programmes to assess current TBT contaminations and resulting biological effects, only relatively young specimens should be considered in the sampling strategy.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1003218411850
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Toxico-kinetic and -dynamic aspects of TBT-induced imposex in Hydrobia ulvae compared with intersex in Littorina littorea (Gastropoda, Prosobranchia) (1998)
    Springer
    Hydrobiologia 378 (1998), S. 215-225 
    Details
    ISSN: 1573-5117
    Schlagwort(e): Hydrobia ulvae ; Littorina littorea ; imposex ; intersex ; reproductive failure ; TBT biomonitoring ; TBT biomonitoring
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A short description of the imposex condition in Hydrobia ulvae is presented. In this species four different imposex stages with two types of development were identified. In laboratory experiments the mud snail accumulates TBT in a time and concentration-dependent manner. Increasing biological indices e.g. VDSI (vas deferens sequence index), female penis length (FPL) and the imposex incidence are significantly correlated with increasing TBT body burden. The percentage of sterile females depends on the TBT contamination of sediments. An interspecific comparison of the mud snail H. ulvae and the periwinkle Littorina littorea elucidates that the mud snail is the more sensitive species at lower environmental TBT concentrations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1003270528688
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Marisa cornuarietis (Gastropoda, prosobranchia): a potential TBT bioindicator for freshwater environments (1995)
    Springer
    Ecotoxicology 4 (1995), S. 372-384 
    Details
    ISSN: 1573-3017
    Schlagwort(e): Imposex ; TBT pollution ; biomonitoring ; reproduction ; Marisa cornuarietis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: The ramshorn snail Marisa cornuarietis (L., 1767) exhibits imposex (occurrence of male parts in addition to the female genital duct) under the influence of TBT (tributyltin) in laboratory experiments and accumulates this biocide in a time-and concentration-dependent manner. A comparison of BCF (bioconcentration factors) demonstrates that this limnic species accumulates more TBT than marine species. Evidence is given that TBT causes hormonal disorders which are responsible for imposex development. The testosterone/oestradiol quotient reflects the imposex development which can be described by a classification scheme differentiating four stages in Marisa cornuarietis. In the background of the constantly increasing organotin concentration in the limnic environment Marisa cornuarietis could be a well-suited bioindicator for TBT pollution. No other limnic species with a lower threshold concentration for measurable TBT effects is reported within the literature.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00118872
    Standort Signatur Erwartet Verfügbarkeit
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