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 کاملEmpty Alternation
We introduce the notion of empty alternation by investigating alternating automata which are restricted to empty their storage except for a logarithmically space-bounded tape before making an alternating transition. In particular, we consider the cases when the depth of alternation is bounded by a constant or a polylogarithmic function. In this way we get new characterizations of the classes AC...
متن کاملThe Impact of Alternation
Alternating automata have been widely used to model and verify systems that handle data from finite domains, such as communication protocols or hardware. The main advantage of the alternating model of computation is that complementation is possible in linear time, thus allowing to concisely encode trace inclusion problems that occur often in verification. In this paper we consider alternating a...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Annals of Botany
سال: 1898
ISSN: 1095-8290,0305-7364
DOI: 10.1093/oxfordjournals.aob.a088720