Library Biological Sciences

Paperback Edition

Paperback$19.95

162 pages

Choose vendor for paperback edition

Purchase from

PDF eBook

Sample Preview Free

Size: 1512k

Download a sample of the first 25 pages


Complete PDF $17

Size: 212k

Get instant access to an entire eBook

How do I open and print my eBook?

Preview & ebook options

Book cover image

Organisation et évolution du génome des Angiospermes

by Carels, Nicolas

  Paperback       e-Book PDF
Institution:   Université Paris VI - Pierre et Marie Curie, France
Advisor(s): M. Giorgio Bernardi
Degree: Ph.D., Genetics
Year: 2000
Volume: 162 pages
ISBN-10: 1581121121
ISBN-13: 9781581121124
Purchase options

Abstract

Les relations gënomiques dëgagëes dans ce travail font apparaÓtre que l'anctre commun des graminëes a subi une transition de la composition en bases qui se traduit par l'augmentation en GC dans tous les consitutants gëniques et gënomiques. Par opposition, cette transition n'a pas eu lieu dans la plupart des autres Monocots et Dicots. La transition compositionnelle renforce l'ëvidence de l'existence de deux classes de gnes chez les Angiospermes : les gnes pauvres et riches en GC. Les premiers sont caractërisës par la prësence d'introns en plus grand nombre et de plus grande longueur que les derniers. Par ailleurs, les deux classes de gnes chez les graminëes ont, sur base de l'ëtude des substitutions synonymes, des taux d'ëvolution diffërents et sont associëes  des plans de fonction diffërents.

La composition en bases est un facteur dëterminant de la localisation des gnes dans le gënome. Chez les graminëes, la plupart des gnes sont concentrës dans un intervalle de composition en bases d'environ 2% de GC. Chez Arabidopsis, la composition en GC est plus ëlevëe aux parties distales des chromosomes que dans leurs parties centrales. La composition en GC des gnes et des sëquences codantes suit la mme tendance. Le gënome d'Arabidopsis peut tre dëcomposë en 2 composantes principales, l'une pauvre en GC correspondant  la partie centrale des chromosomes, l'autre riche en GC, et quantitativement plus importante, correspondant aux parties distales des chromosomes. L'expression des gnes associës  la composante riche en GC  ëtë trouvëe, en moyenne, supërieure  celle des gnes de l'autre composante. La compilation de nos rësultats et de ceux disponibles dans la littërature suggre que le plan de base de l'organisation du gënome est similaire chez les graminëes.

The work shows, by a detailed analysis of the genomic features of Gramineae, that their common ancestor did the experience of a compositional transition leading to the increase in GC level of all parts of the genome and of the genes. By contrast, this transition did not occur in a number of Dicots and Monocots. With regard to GC level of the genes, the compositional transition stresses the existence of two classes of genes in Angiosperms. The GC-poor genes are characterized by introns higher in average number and size compared to GC-rich genes. Moreover, by analysing synonymous and non-synonymous substitutions, we showed that the evolution rates in the two classes of genes are different and correspond to different functional patterns.

The base composition is a determinant of gene location within the Angiosperm genomes. In Gramineae, most genes occur in genomic regions that have a narrow range of GC levels (about 2%). In Arabidopsis, the GC level of contigs is higher, on the average, in the distal regions of chromosomes compared to their central regions. The GC levels of genes and coding sequences follow the same trend. The Arabidopsis genome is made up of two major components. One is GC-poor and corresponds to the central part of the chromosomes, the other, quantitatively higher, is in comparison GC-rich and corresponds to the distal regions of chromosomes. Gene expression is generally higher in this GC-rich component. The sum of our results and those available in the literature suggest that the genome organization of Gramineae is basically similar.

Paperback Edition

Paperback$19.95

162 pages

Choose vendor for paperback edition

Purchase from

PDF eBook

Sample Preview Free

Size: 1512k

Download a sample of the first 25 pages


Complete PDF $17

Size: 212k

Get instant access to an entire eBook

How do I open and print my eBook?

Preview & ebook options