Search results for "SYMBIOSIS"
showing 10 items of 627 documents
Female mate choice in convict cichlids is transitive and consistent with a self-referent directional preference
2013
10 pages; International audience; INTRODUCTION: One of the most important decisions that an animal has to make in its life is choosing a mate. Although most studies in sexual selection assume that mate choice is rational, this assumption has not been tested seriously. A crucial component of rationality is that animals exhibit transitive choices: if an individual prefers option A over B, and B over C, then it also prefers A over C. RESULTS: We assessed transitivity in mate choice: 40 female convict cichlids had to make a series of binary choices between males of varying size. Ninety percent of females showed transitive choices. The mean preference index was significantly higher when a female…
Parasite-induced behavioral change: mechanisms.
2010
Animal behavior and parasitism are more tightly linked than commonly thought. One of the most astonishing phenomena in host–parasite antagonistic interactions is ‘host manipulation,’ that is, the ability of a parasite to alter the behavior of its host in ways that appear to increase parasite fitness at the expense of host fitness. The mechanisms by which a parasite hijacks the behavior of its host have been explored using ethopharmacological and immunocytochemical approaches or carrying out a large-scale proteomic study on manipulated host’s brain. These few mechanistic studies have confirmed both the complexity of host manipulation by parasites and the importance of understanding the molec…
Effects of Arbuscular Mycorrhizal Fungi on the Vegetative Vigor of Ailanthus altissima (Mill.) Swingle Seedlings under Sustained Pot Limitation
2018
In order to invade new ecosystems, invasive alien plants need to cope with different microbial communities. Whilst the ability to avoid antagonists is well recognized, the opportunity to establish mutualistic associations is less known, even in widespread invasive species such as Ailanthus altissima (Mill.) Swingle. We sought to evaluate whether the beneficial effects of arbuscular mycorrhizal fungi (AMF) on Ailanthus seedlings are maintained over time, under prolonged pot limitation. We compared three-month-, three-year- and four-year-old mycorrhizal seedlings grown in natural forest soil (NT) with seedlings grown in sterilized (ST) and non-mycorrhizal (NM) soils, in pots of 3.4 L (22 &tim…
25S rDNA-based molecular monitoring of glomalean fungi in sewage sludge-treated field plots
2001
Recycling of sewage wastes in agriculture is likely to affect the biological activity of soils through contamination of ecosystems by pathogens and metallic or organic micropollutants. The impact of sewage sludge spreading under field conditions on arbuscular mycorrhiza (AM) formation by a community of glomalean fungi was evaluated using a nested polymerase chain reaction (PCR) and discriminating primers based on 25S rDNA polymorphisms to detect different fungal species within root systems. Medicago truncatula was grown in soil of field plots amended or not with a composted sewage sludge, spiked or not with organic or metallic micropollutants. Overall AM development in roots decreased with …
Sugar transporters in plants and in their interactions with fungi.
2012
International audience; Sucrose and monosaccharide transporters mediate long distance transport of sugar from source to sink organs and constitute key components for carbon partitioning at the whole plant level and in interactions with fungi. Even if numerous families of plant sugar transporters are defined; efflux capacities, subcellular localization and association to membrane rafts have only been recently reported. On the fungal side, the investigation of sugar transport mechanisms in mutualistic and pathogenic interactions is now emerging. Here, we review the essential role of sugar transporters for distribution of carbohydrates inside plant cells, as well as for plant fungal interactio…
Can sucrose content in the phloem sap reaching field pea seeds (Pisum sativum L.) be an accurate indicator of seed growth potential ?
2003
The composition of the translocates reaching the seeds of pea plants having various nitrogen (N) nutrition regimes was investigated under field situations. Sucrose flow in the phloem sap increased with the node number, but was not significantly different between N nutrition levels. Because N deficiency reduced the number of flowering nodes and the number of seeds per pod, the sucrose flow bleeding from cut peduncles was divided by the number of seeds to give the amount of assimilates available per seed. The sucrose concentration in phloem sap supplied to seeds at the upper nodes was higher than that at the lower nodes. The flow of sucrose delivered to the seeds during the cell division peri…
The Medicago truncatula sucrose transporter family: characterization and implication of key members in carbon partitioning towards arbuscular mycorrh…
2012
We identified de novo sucrose transporter (SUT) genes involved in long-distance transport of sucrose from photosynthetic source leaves towards sink organs in the model leguminous species Medicago truncatula. The iden- tification and functional analysis of sugar transporters provide key information on mechanisms that underlie carbon partitioning in plant-microorganism interactions. In that way, full-length sequences of the M. truncatula SUT (MtSUT) family were retrieved and biochemical characterization of MtSUT members was performed by heterologous expression in yeast. The MtSUT family now comprises six genes which distribute among Dicotyledonous clades. MtSUT1-1 and MtSUT4-1 are key members…
Genome sequence of the pea aphid Acyrthosiphon pisum
2010
The genome of the pea aphid shows remarkable levels of gene duplication and equally remarkable gene absences that shed light on aspects of aphid biology, most especially its symbiosis with Buchnera.
Arbuscular mycorrhiza and fungal root endophytes of weeds in an altitudinal gradient in the Pamir Alai Mountains of Central Asia
2014
Arbuscular mycorrhiza and fungal root endophytes of three weeds, Galium tricornutum, Lycopsis orientalis and Scandix pecten-veneris, were studied in an altitudinal gradient of the Pamir Alai Mountains. Colonisation by arbuscular mycorrhizal fungi (AMF) was found in all species. Only in the case of G. tricornutum was there a rise in mycorrhizal parameters values found for the medium altitude range. Similar tendencies were observed in the case of the AMF colonisation potential assessment. This suggests that plant species' identity, dependency on symbiosis and interactions with soil properties determine root colonisation and the abundance of AMF in soils at the elevations in question. Four AMF…
Genome reduction of the aphid endosymbiont Buchnera aphidicola in a recent evolutionary time scale.
2007
International audience; Genome reduction, a typical feature of symbiotic bacteria, was analyzed in the last stages of evolution of Buchnera aphidicola, the primary aphid endosymbiont, in two neutrally evolving regions: the pseudogene cmk and an intergenic region. These two regions were examined in endosymbionts from several lineages of their aphid host Rhopalosiphum padi, and different species of the same genus, whose divergence times ranged from 0.62 to 19.51 million years. Estimates of nucleotide substitution rates were between 4.3 and 6.7 x 10(-9) substitution/site/year, with G or C nucleotides being substituted around four times more frequently than A or T. Two different types of indel …