ISSN:
1438-3888
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Description / Table of Contents:
Resume 1. La caryogamie est supprimée dans des zygotes obtenus à partir d'une souche sauvage unialgale de l'Acrosiphonia arcta (Dillw.)J. Ag. de Héligoland. 2. Les deux pronucléi des pseudozygotes ainsi formés peuvent se séparer définitivement au moment de la première segmentation de l'élément zygotique qui intervient au bout d'une quinzaine de jours. 3. Les pseudozygotes se développment directement en nouvelles plantes d'Acrosiphonia. 4. Les plantes issues de pseudozygotes ainsi que les plantes-mères possèdent des noyaux haploïdes avec n=5 chromosomes. 5. L'Acrosiphonia arcta d'origine apocaryogamique semble constituer des lignées micto-haploïdes stables et génétiquement isolées. Leur origine et leur mode de ségrégation sont discutés.
Notes:
Abstract Nuclear studies of zygotes obtained from the wild type ofAcrosiphonia arcta (Dillw.)J. Ag. from Helgoland were carried out in order to test the hypothesis that these algae might be of apocaryogamic origin. It is shown that caryogamy may be completely suppressed in zygotes of this species, although plasmogamy is normally carried out. The two pronuclei which do not fuse, become definitively separated after the first segmentation of zygote. In culture, these zygotes develop directly into filamentous plants which are morphologically similar to those from which they originate. These plants possess haploid nuclei with n=5 chromosomes. The same chromosome number is found in the mother plants. Since successive generations continue to reproduce by apocaryogamy, it is suggested that genetically isolated micto-haploid strains occur in theA. arcta population studied. Origin and segregation of such strains are discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01609463
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