The distribution of fibronectin and laminin in the somitogenesis of Xenopus laevis.
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D Wedlich
Publications and source records attributed to D Wedlich.
Method for epitope selection of antisera for immunohistology.
Polyclonal anti-laminin serum was affinity-purified on paraformaldehyde-fixed laminin on a nitrocellulose filter. The purified antibodies were tested for their specificity in immunohistological stainings on frozen sections of paraformaldehyde-fixed tissue. As compared to the initial polyclonal serum, the purified antibodies increased the specificity of antigen detection, since all background caused by nonspecific reactions was eliminated. This technique promises to be very useful for immunohistological analysis using light and electron microscopy.
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Cell specificity of nuclear protein antigens in the development of Xenopus species.
Protein antigens accumulated in the oocyte nucleus of Xenopus spp. are found later in all nuclei of the embryo. During and after organogenesis, the fate of different nuclear antigens diverges: Some are permanently expressed in all nuclei, some are no longer detectable in any nuclei, and some show a high degree of specificity relative to cell type. Of the class of antigens permanently expressed in all cells, a nucleolar antigen has been studied that is relatively enriched in the gonia of both sexes. A possible correlations of its occurrence with ribosomal DNA amplification and transcription is examined. The cell-specific expression of 4 antigens has been analyzed in detail, using indirect immunofluorescent staining methods as well as conventional histology. The tissue-specificity of 2 of these antigens does not change during metamorphosis, whereas the pattern of others is dynamic until after metamorphosis. We conclude that the observed tissue-specificity does not correlate with descendence from one of the 3 primary germ layers: Some antigens appear to accumulate in the nucleus when a cell takes up its specific function.
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The distribution of nucleoplasmin in early development and organogenesis of Xenopus laevis.
The fate of the germinal vesicle-derived protein, nucleoplasmin, was followed in embryos and tadpoles of Xenopus using monoclonal antibodies and indirect immunofluorescent staining. Nucleoplasmin was found in all nuclei up to feeding tadpole stages. Thereafter its level decreased in all nuclei. It was not detected in nuclei of advanced tadpoles or of adults. Contrasting with another protein, N1, that was previously monitored in the nuclei of dividing gonia of both sexes, nucleoplasmin was only detected in the nuclei of ovarian oocytes starting at diplotene. Traces of nucleoplasmin have also been found in a rapidly-dividing fibroblastic cell-line by immunohistology and protein blotting.
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Occurrence of a species-specific nuclear antigen in the germ line of Xenopus and its expression from paternal genes in hybrid frogs.
An abundant acidic germinal vesicle protein of 100,000 Da has been previously described in Xenopus laevis and termed N1. It is supposed to bind stored histones in the oocyte. Species-specific monoclonal antibodies (mABs) have been raised against the oocyte nuclear protein of X. borealis B3, that is equivalent to protein N1 of X. laevis. These mABs have been used to monitor paternal gene expression of B3 in hybrids between X. laevis and X. borealis. Protein B3 is accumulated in oocyte nuclei, shed into the cytoplasm of the egg upon germinal vesicle breakdown, and reaccumulated by the nuclei of the embryo. During development it appears to be gradually diluted in all cells of the embryo, its levels falling below the limits of detection after stage 50. In interspecies hybrids, the paternal antigen is not found in somatic cells, as judged by immunohistological criteria. Therefore it has been concluded that protein B3 is not expressed from the genes of the embryo and that the maternal store of B3 is sufficient to endow the nuclei of the embryo with this protein up to the feeding tadpole stage. This deduction is corroborated by radiolabeling experiments. The paternal antigen B3 is, however, specifically expressed in the germ line. In hybrids and in X. borealis it is first detected in the nuclei of oogonia and spermatogonia, but, in both sexes, it is undetectable during early meiotic prophase. In female germ cells, accumulation of B3 is resumed at the beginning of diplotene, concomitant with the onset of oocyte growth. The significance of the observed cell specificity of B3 during germ cell differentiation is discussed in relation to its postulated function as a histone storage factor.
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