منابع مشابه
Origin of Alternation of Generations
Alternation of generations is a common component of all land plants, vascular and nonvascular; it does not express itself in the same manner in any other organisms. Given the other overwhelming similarities in land plant biochemistry, photosynthetic pigments and tissue organization, it seems that the easiest assumption is that they are derivatives of a common ancestor. The origin of alternation...
متن کاملSexual conflict and the alternation of haploid and diploid generations.
Land plants possess a multicellular diploid stage (sporophyte) that begins development while attached to a multicellular haploid progenitor (gametophyte). Although the closest algal relatives of land plants lack a multicellular sporophyte, they do produce a zygote that grows while attached to the maternal gametophyte. The diploid offspring shares one haploid set of genes with the haploid mother...
متن کاملAlternation of generations - unravelling the underlying molecular mechanism of a 165-year-old botanical observation.
Characteristically, land plants exhibit a life cycle with an 'alternation of generations' and thus alternate between a haploid gametophyte and a diploid sporophyte. At meiosis and fertilisation the transitions between these two ontogenies take place in distinct single stem cells. The evolutionary invention of an embryo, and thus an upright multicellular sporophyte, in the ancestor of land plant...
متن کاملcausative alternation in persian
in this article, the causative alternation in persian is discussed. first, it is shown that persian anticausative verbs involve a cause component and an implicit external argument. second, we claim that causative alternation arises when a single change-of-state verb invokes more than one semantic frame (fillmore, 1985): causative frame and anticausative frame. these semantic frames are the resu...
متن کاملPhylogenetic analysis of ligninolytic peroxidases: preliminary insights into the alternation of white-rot and brown-rot fungi in their lineage
White-rot and brown-rot fungi employ different mechanisms to degrade lignocellulose. These fungi are not monophyletic and even alternate in their common lineage. To explore the reason for this, seventy-six ligninolytic peroxidases (LPs), including 14 sequences newly identified from available basidiomycetous whole-genome and EST databases in this study, were utilized for phylogenetic and selecti...
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ژورنال
عنوان ژورنال: Nature
سال: 1871
ISSN: 0028-0836,1476-4687
DOI: 10.1038/005122a0