Nucleolar cycle and localization of NORs in early embryos of Parascaris univalens
| العنوان: | Nucleolar cycle and localization of NORs in early embryos of Parascaris univalens |
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| المؤلفون: | José A. Suja, Carmen Antonio, José M. González-García, Julio S. Rufas |
| المصدر: | Chromosoma. 104:287-297 |
| بيانات النشر: | Springer Science and Business Media LLC, 1995. |
| سنة النشر: | 1995 |
| مصطلحات موضوعية: | Nucleologenesis, Fibrillarin, Blastomeres, Staining and Labeling, Chromosomal Proteins, Non-Histone, Somatic cell, Nucleolus, Cell Cycle, Autoimmunity, Biology, Molecular biology, Chromatin, Prophase, Nucleolus Organizer Region, Genetics, Animals, Female, Horses, Ascaridida, Metaphase, Cell Nucleolus, In Situ Hybridization, Fluorescence, Genetics (clinical), Anaphase |
| الوصف: | During early embryogenesis of the nematode Parascaris univalens (2n=2) the processes of chromatin diminution and segregation of the germ and somatic cell lineages take place simultaneously. In this study we analyzed the nucleolar cycle in early embryos, both in germinal and somatic blastomeres, by means of silver staining and antibodies against the nucleolar protein fibrillarin. We observed an identical nucleolar cycle in both types of blastomeres, hence, the chromatin diminution process has no effect on the nucleolar cycle of somatic blastomeres. We report the existence of outstanding differences between this cycle and those previously reported during early embryogenesis of other species. There is a true nucleolar cycle in early embryos that shows a peculiar nucleolar disorganization at prophase, and a preferential localization of prenucleolar bodies only on the euchromatic regions during nucleologenesis. Moreover, fibrillarin does not form a perichromosomal sheath in metaphase or anaphase holocentric chromosomes, probably owing to their special centromeric organization. The number and location of nucleolus organizer regions (NORs) in the chromosomal complement have been determined using silver impregnation, chromomycin A3/ distamycin A staining, and fluorescent in situ hybridization using an rDNA probe. There are only two NORs, one per chromosome, and these are located in the middle of the euchromatic central regions. This location implies that no rDNA sequences are lost in blastomeres after chromatin diminution. Moreover, the constant presence of two nucleoli in somatic blastomeres suggests that NORs are not affected during the fragmentation of euchromatic regions when this process occurs. |
| تدمد: | 1432-0886 0009-5915 |
| الوصول الحر: | https://explore.openaire.eu/search/publication?articleId=doi_dedup___::51b2445bddd80b18ab7d708bba363afbTest https://doi.org/10.1007/s004120050118Test |
| حقوق: | CLOSED |
| رقم الانضمام: | edsair.doi.dedup.....51b2445bddd80b18ab7d708bba363afb |
| قاعدة البيانات: | OpenAIRE |
| تدمد: | 14320886 00095915 |
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