Biparental inheritance of plastidial and mitochondrial DNA and hybrid variegation in Pelargonium

Plastidial (pt) and mitochondrial (mt) genes usually show maternal inheritance. Non-Mendelian, biparental inheritance of plastids was first described by Baur (Z Indukt Abstamm Vererbungslehre 1:330–351, 1909) for crosses between Pelargonium cultivars. We have analyzed the inheritance of pt and mtDNA by examining the progeny from reciprocal crosses of Pelargoniumzonale and P. inquinans using nucleotide sequence polymorphisms of selected pt and mt genes. Sequence analysis of the progeny revealed biparental inheritance of both pt and mtDNA. Hybrid plants exhibited variegation: our data demonstrate that the inquinans chloroplasts, but not the zonale chloroplasts bleach out, presumably due to incompatibility of the former with the hybrid nuclear genome. Different distribution of maternal and paternal sequences could be observed in different sectors of the same leaf, in different leaves of the same plant, and in different plants indicating random segregation and sorting-out of maternal and paternal plastids and mitochondria in the hybrids. The substantial transmission of both maternal and paternal mitochondria to the progeny turns Pelargonium into a particular interesting subject for studies on the inheritance, segregation and recombination of mt genes

Recent Acceleration of Plastid Sequence and Structural Evolution Coincides with Extreme Mitochondrial Divergence in the Angiosperm Genus Silene

The angiosperm genus Silene exhibits some of the most extreme and rapid divergence ever identified in mitochondrial genome architecture and nucleotide substitution rates. These patterns have been considered mitochondrial specific based on the absence of correlated changes in the small number of available nuclear and plastid gene sequences. To better assess the relationship between mitochondrial and plastid evolution, we sequenced the plastid genomes from four Silene species with fully sequenced mitochondrial genomes. We found that two species with fast-evolving mitochondrial genomes, S. noctiflora and S. conica, also exhibit accelerated rates of sequence and structural evolution in their plastid genomes. The nature of these changes, however, is markedly different from those in the mitochondrial genome. For example, in contrast to the mitochondrial pattern, which appears to be genome wide and mutationally driven, the plastid substitution rate accelerations are restricted to a subset of genes and preferentially affect nonsynonymous sites, indicating that altered selection pressures are acting on specific plastid-encoded functions in these species. Indeed, some plastid genes in S. noctiflora and S. conica show strong evidence of positive selection. In contrast, two species with more slowly evolving mitochondrial genomes, S. latifolia and S. vulgaris, have correspondingly low rates of nucleotide substitution in plastid genes as well as a plastid genome structure that has remained essentially unchanged since the origin of angiosperms. These results raise the possibility that common evolutionary forces could be shaping the extreme but distinct patterns of divergence in both organelle genomes within this genus

The representations of riders in Egypt at the Ptolemaic and Roman times and the influence of foreign iconography

Aux époques ptolémaïque et impériale, les représentations de cavaliers se multiplient et de nouveaux motifs apparaissent en Égypte. Des divinités du panthéonpharaonique peuvent être dotées d’un cheval et d’attributs militaires. Des dieux étrangers font leur apparition ainsi que des personnages cuirassés et armés dont lanature divine n’est pas avérée. Le présent travail constitue une première monographie sur l’ensemble de ces représentations. Le catalogue comporte cent quarante‐huit objets et présente une hétérogénéité importante, tant du point de vue des supports que des sites d’où proviennent les sources. Axée sur l’interdisciplinarité, la thèse repose sur deux approches, technique et iconographique. L’étude du mode de fabrication des figurines en terre cuite et les réflexions sur la question de la mise en série des objets constituent le premier champ de recherches. L’axe iconographique repose sur la comparaison systématique des motifs iconographiques avec les emblèmes visibles dans le reste du pourtour du bassin méditerranéen et traite de la signification des représentations. La confrontation des données a permis d’établir des hypothèses sur l’origine et la fonction des terres cuites et sur les raisons qui ont mené à la production des objets du corpus.Des critères de datation nouveaux ont été définis pour tenter de pallier les lacunes dues à l’absence de contexte de la majorité des sources du catalogue. Les travaux effectués dans les musées ont permis de publier des reproductions de qualité pour des objets qui pour certains n’avaient plus été observés depuis 1915. Ils ont également donné lieu à la découverte d’inédits.During the Ptolemaic and Imperial times in Egypt we find increasing representations of horsemen, and new emblems start to appear. Divinities of the Pharaonic pantheon are sometimes endowed with a horse and military attributes. Foreign gods also begin to appear, as do cuirassed and armed characters, whose divinity is unproven. This study is a first attempt to produce a monograph encompassing all of these representations. The catalogue contains 148 objects and has a significant degree of heterogeneity, both with regard to the items themselves and to the sites from which they come from. With a strongly interdisciplinary approach, the thesis is based on two methods of investigation: the technical and the iconographic. The first area of researches comprises an examination of the method of manufacture of the terracotta figurines and some thoughts regarding the series production of the objects. The iconographic approach is based on a systematic comparison of the iconographic attributes with the emblems that can be seen around the rest of the Mediterranean, and considers the significance of these representations. By comparing data, it has been possible to make assumptions regarding the origin and purpose of the terracotta figurines, and the reasons which led to the production of the objects comprising the study. New dating criteria have been defined in an effort to bridge the gaps caused by the lack of context for the majority of sources listed in the catalogue. Work done in the museums has allowed the creation of high‐quality reproductions of the objects, some of which were last examined in 1915; it has also resulted in the discovery of previously unpublished material

Study of a plant specific family of proteins involved in organellar genome maintenance

Pas de résuméPas de résum

The representations of riders in Egypt at the Ptolemaic and Roman times and the influence of foreign iconography

Aux époques ptolémaïque et impériale, les représentations de cavaliers se multiplient et de nouveaux motifs apparaissent en Égypte. Des divinités du panthéonpharaonique peuvent être dotées d’un cheval et d’attributs militaires. Des dieux étrangers font leur apparition ainsi que des personnages cuirassés et armés dont lanature divine n’est pas avérée. Le présent travail constitue une première monographie sur l’ensemble de ces représentations. Le catalogue comporte cent quarante‐huit objets et présente une hétérogénéité importante, tant du point de vue des supports que des sites d’où proviennent les sources. Axée sur l’interdisciplinarité, la thèse repose sur deux approches, technique et iconographique. L’étude du mode de fabrication des figurines en terre cuite et les réflexions sur la question de la mise en série des objets constituent le premier champ de recherches. L’axe iconographique repose sur la comparaison systématique des motifs iconographiques avec les emblèmes visibles dans le reste du pourtour du bassin méditerranéen et traite de la signification des représentations. La confrontation des données a permis d’établir des hypothèses sur l’origine et la fonction des terres cuites et sur les raisons qui ont mené à la production des objets du corpus.Des critères de datation nouveaux ont été définis pour tenter de pallier les lacunes dues à l’absence de contexte de la majorité des sources du catalogue. Les travaux effectués dans les musées ont permis de publier des reproductions de qualité pour des objets qui pour certains n’avaient plus été observés depuis 1915. Ils ont également donné lieu à la découverte d’inédits.During the Ptolemaic and Imperial times in Egypt we find increasing representations of horsemen, and new emblems start to appear. Divinities of the Pharaonic pantheon are sometimes endowed with a horse and military attributes. Foreign gods also begin to appear, as do cuirassed and armed characters, whose divinity is unproven. This study is a first attempt to produce a monograph encompassing all of these representations. The catalogue contains 148 objects and has a significant degree of heterogeneity, both with regard to the items themselves and to the sites from which they come from. With a strongly interdisciplinary approach, the thesis is based on two methods of investigation: the technical and the iconographic. The first area of researches comprises an examination of the method of manufacture of the terracotta figurines and some thoughts regarding the series production of the objects. The iconographic approach is based on a systematic comparison of the iconographic attributes with the emblems that can be seen around the rest of the Mediterranean, and considers the significance of these representations. By comparing data, it has been possible to make assumptions regarding the origin and purpose of the terracotta figurines, and the reasons which led to the production of the objects comprising the study. New dating criteria have been defined in an effort to bridge the gaps caused by the lack of context for the majority of sources listed in the catalogue. Work done in the museums has allowed the creation of high‐quality reproductions of the objects, some of which were last examined in 1915; it has also resulted in the discovery of previously unpublished material

Study of a plant specific family of proteins involved in organellar genome maintenance

Pas de résuméPas de résum