Nucleus higher plant

The eukaryotes these include animals, plants, fungi and protozoa, the DNA of which is enclosed in a membrane-enclosed organelle (the cell nucleus). They have a cytoskeleton (a fine membrane-like network in the interior of the cell, which provides stability) and contain mitochondria. Higher plants, as well as algae, are equipped with chloroplasts for photosynthesis. 

The simple coumarin nucleus (Fig 7.3), which is derived by lactone formation of an ortho-hydroxy-czs cinnamic acid, is a common metabolite in higher plants and is often found in glycosidic form. Coumarins are common in Api-aceae, in certain genera of Fabaceae (e.g. Dipteryx odorata, Melilotus officinalis), Poaceae (e.g. Anthoxanthum odoratum) and Rubiaceae (e.g. Galium odoratum). However, proliferation of coumarins to the status of major chemical markers occurs in only a few cases, most notably, but not exclusively, in the Api-aceae (subfamily Apioideae) and in the Rutaceae (Gray and Waterman, 1978 Murray et al., 1982). In these cases, the coumarin nucleus has almost invariably been embellished by the addition of a prenyl unit leading to furocoumarin (Fig 7.3) and pyranocoumarin structures. 

There is an alternative way of viewing the above results, however. It could be that the biosynthetic pathway to the pyrrolidine ring of nicotine is similar (in part) to the route to the piperidine alkaloids. Part of the model suggested for the biosynthesis of the piperidine nucleus from lysine (see above) could be easily adapted to account for the C02 and nornicotine results, that is variable/in-complete equilibration of bound putrescine (arising by enzyme-mediated decarboxylation of ornithine) with unbound material. L-Ornithine decarboxylase (EC 4.1.1.17, L-ornithine carboxy-lyase) occurs widely in higher plants and like L-lysine decarboxylase requires pyridoxal phosphate as a co-factor. ... 

D. More tonnage of 2,4-D type herbicide is still used than other herbicides, so algae cannot be used as the sole test organism. Cyanobacteria (blue-green algae) are even less representative of plants. They lack a higher plant type nucleus, and thus dinitroaniline type herbicides which prevent the tubulin formation necessary for nuclear division are inactive (Table I). 

Finally, profilins have been reported as residents of the nucleus. Immunofluorescence revealed nuclear profilin I in fibroblasts and epithehal cells (Mayboroda et al. 1997 Skare et al. 2003) and in bovine oocyte germinal vesicles and early embryos (Rawe et al. 2006). Nuclear profilin has also been described in several higher plants (see Hussey et al. 2006 for original references). Additionally, the existence of nuclear profilin-actin complexes can be deduced from studies on HeLa cells and Xenopus oocytes (Striven et al. 2003). In a recent study with GFP-profilin transfected cells and polyclonal anti-serum, profilin II has been shown to accumulate in the nucleus of hippocampal neurons. This concentration was de-... 

The activity of multi-cellular organisms like higher plants depends on the Interaction of a number of regulatory systems which can be represented schematically by a sequence of regulators, first that of a cell (gene, chromosome, nucleus, cytoplasm), then of a tissue and. 

With the possibility of the 1-deoxyxylulose 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway to the hemiterpene units, IPP and DMAPP, operating in higher plants, it will be of interest to establish whether the five-carbon unit incorporated into the quinoline nucleus is preferentially derived from mevalonic acid or 1 -deoxyxylulose. 

Anthraquinones derived from acetate-malonate pathways are particularly common in fungi and lichens, but are often found in higher plants as well. Acetate-malonate-de-rived anthraquinones usually can be distinguished by their structures because they possess substituents in both benze-noid rings of the anthraquinone nucleus (also see Chapter 5), although there are some exceptions to this generalization. 

Phylloquinone is a constituent of higher plants. Its structure is similar to vitamin K2 in that it also contains the menadione nucleus to which, however, a phytyl residue (one unsaturated and three saturated isoprene units) is attached (Fig. 4). Phylloquinone occurs in chloroplasts of... 

The biosynthesis of this group of compounds is confined almost exclusively to higher plants and algae and whilst the steps in the formation of the quinone or aromatic nucleus are in most cases fairly well understood the pathways utilised for the subsequent... 

Examination of some of the features of the biosynthesis of phylloquinones such as (9) in higher plants and of menaquinones (10) in bacteria has shown that the pol5qjrenyl chains and nuclear C methyl groups arise imexceptionally from (R)-mevalonic acid (11) and L-methionine respectively The aspect of biosynthesis which has commanded most attention is the building of the naphthoquinone nucleus from (—)-shikimic acid and almost all of the critical and pertinent observations upon this intriguing problem have been made in relation to menaquinones from bacterial sources. 

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