Search results for "SYMBIOSIS"
showing 10 items of 627 documents
Evidence of Recombination in Intrapatient Populations of Hepatitis C Virus.
2008
Hepatitis C virus (HCV) is a major cause of liver disease worldwide and a potential cause of substantial morbidity and mortality in the future. HCV is characterized by a high level of genetic heterogeneity. Although homologous recombination has been demonstrated in many members of the family Flaviviridae, to which HCV belongs, there are only a few studies reporting recombination on natural populations of HCV, suggesting that these events are rare in vivo. Furthermore, these few studies have focused on recombination between different HCV genotypes/subtypes but there are no reports on the extent of intra-genotype or intra-subtype recombination between viral strains infecting the same patient.…
Differential competitive ability between sexes in the dioecious Antennaria dioica (Asteraceae)
2012
† Background and Aims Differences in competitive ability between the sexes of dioecious plants are expected as a result of allocation trade-offs associated with sex-differential reproductive costs. However, the available data on competitive ability in dioecious plants are scarce and contradictory. In this study sexual competition was eval- uated using the dioecious plant Antennaria dioica in a common garden transplantation experiment. † Methods Male and female plants were grown for 3 years either in isolation, or in competition with a plant of the same sex or the opposite sex. Flowering phenology, sexual and asexual reproduction, plant growth, nutrient content and arbuscular mycorrhizal col…
Variable mycorrhizal benefits on the reproductive output ofGeranium sylvaticum, with special emphasis on the intermediate phenotype
2012
In several gynodioecious species, intermediate sex between female and hermaphrodite has been reported, but few studies have investigated fitness parameters of this intermediate phenotype. Here, we examined the interactions between plant sex and arbuscular mycorrhizal (AM) fungal species affecting the reproductive output of Geranium sylvaticum, a sexually polymorphic plant species with frequent intermediate sexes between females and hermaphrodites, using a common garden experiment. Flowering phenology, AM colonisation levels and several plant vegetative and reproductive parameters, including seed and pollen production, were measured. Differences among sexes were detected in flowering, fruit …
Climate change and cyclic predator-prey population dynamics in the high Arctic.
2009
The high Arctic has the world's simplest terrestrial vertebrate predator–prey community, with the collared lemming being the single main prey of four predators, the snowy owl, the Arctic fox, the long-tailed skua, and the stoat. Using a 20-year-long time series of population densities for the five species and a dynamic model that has been previously parameterized for northeast Greenland, we analyzed the population and community level consequences of the ongoing and predicted climate change. Species' responses to climate change are complex, because in addition to the direct effects of climate change, which vary depending on species' life histories, species are also affected indirectly due to…
Endosymbiont communities in Bemisia tabaci: a metagenomic approach
2014
Este trabajo es parte de un programa de investigación que tiene como objetivo dilucidar la evolución de las bacterias endosimbiontes utilizando los consorcios insecto-bacteria como modelo. Los diferentes estudios realizados sobre los insectos y sus bacterias endosimbiontes han arrojado luz sobre los cambios ocurridos tras la adquisición de una forma de vida intracelular, así cómo la interacción entre diferentes endosimbiontes formando comunidades endosimbioticas. Dos son los objetivos principales de este trabajo. El primera (capítulos “Portiera y su socio Hamiltonella” y “El tercer pasajero: Cardinium cBtQ1)” trata de analizar y describir las relaciones de la comunidad endosimbiótica en B. …
Two Host Clades, Two Bacterial Arsenals: Evolution through Gene Losses in Facultative Endosymbionts.
2015
International audience; Bacterial endosymbiosis is an important evolutionary process in insects, which can harbor both obligate and facultative symbionts. The evolution of these symbionts is driven by evolutionary convergence, and they exhibit among the tiniest genomes in prokaryotes. The large host spectrum of facultative symbionts and the high diversity of strategies they use to infect new hosts probably impact the evolution of their genome and explain why they undergo less severe genomic erosion than obligate symbionts. Candidatus Hamiltonella defensa is suitable for the investigation of the genomic evolution of facultative symbionts because the bacteria are engaged in specific relations…
What Symbionts Teach us about Modularity
2013
The main goal of Synthetic Biology is to apply engineering principles to biotechnology in order to make life easier to engineer. These engineering principles include modularity: decoupling of complex systems into smaller, orthogonal subsystems that can be used in a range of different applications. The successful use of modules in engineering is expected to be reproduced in synthetic biological systems. But the difficulties experienced up to date with synthetic biology approaches question the short-term feasibility of designing life. Considering the “engineerable” nature of life, here we discuss the existence of modularity in natural living systems, particularly in symbiotic interactions, an…
EX VITRO MYCORRHIZATION OF VITRO-DERIVED PLANTLETS OF 'CARRIZO' CITRANGE [C. SINENSIS (L.) OSB. × P. TRIFOLIATA (L.) RAF.]
2015
In this study, vitro-derived plantlets of âCarrizoâ citrange were inoculated with Glomus intraradices during the acclimatization phase, from in vitro to in vivo. Plantlets were grown in presence (+M) and in absence of inoculum (-M) and in addition, in sterile and non-sterile substrate. After three months of culture, some vegetative parameters and the level of infection, varied greatly in the different theses. In particular, the highest formation of new branched roots has been observed in inoculated plantlets cultivated in sterile substrate. Good results were observed also in non-inoculated plantlets cultivated in non-sterile substrate, in presence of endemic inoculum. The same trend was…
High Temperatures Result in Smaller Nurseries which Lower Reproduction of Pollinators and Parasites in a Brood Site Pollination Mutualism
2014
In a nursery pollination mutualism, we asked whether environmental factors affected reproduction of mutualistic pollinators, non-mutualistic parasites and seed production via seasonal changes in plant traits such as inflorescence size and within-tree reproductive phenology. We examined seasonal variation in reproduction in Ficus racemosa community members that utilise enclosed inflorescences called syconia as nurseries. Temperature, relative humidity and rainfall defined four seasons: winter; hot days, cold nights; summer and wet seasons. Syconium volumes were highest in winter and lowest in summer, and affected syconium contents positively across all seasons. Greater transpiration from the…
Proteome adaptations under contrasting soil phosphate regimes of Rhizophagus irregularis engaged in a common mycorrhizal network.
2021
International audience; For many plants, their symbiosis with arbuscular mycorrhizal fungi plays a key role in the acquisition of mineral nutrients such as inorganic phosphate (Pi), in exchange for assimilated carbon. To study gene regulation and function in the symbiotic partners, we and others have used compartmented microcosms in which the extra-radical mycelium (ERM), responsible for mineral nutrient supply for the plants, was separated by fine nylon nets from the associated host roots and could be harvested and analysed in isolation. Here, we used such a model system to perform a quantitative comparative protein profiling of the ERM of Rhizophagus irregularis BEG75, forming a common my…