Search results for "Computing"
showing 10 items of 25279 documents
Behavior of plant plasma membranes under hydrostatic pressure as monitored by fluorescent environment-sensitive probes.
2010
International audience; We monitored the behavior of plasma membrane (PM) isolated from tobacco cells (BY-2) under hydrostatic pressures up to 3.5 kbar at 30 °C, by steady-state fluorescence spectroscopy using the newly introduced environment-sensitive probe F2N12S and also Laurdan and di-4-ANEPPDHQ. The consequences of sterol depletion by methyl-β-cyclodextrin were also studied. We found that application of hydrostatic pressure led to a marked decrease of hydration as probed by F2N12S and to an increase of the generalized polarization excitation (GPex) of Laurdan. We observed that the hydration effect of sterol depletion was maximal between 1 and 1.5 kbar but was much less important at hig…
Soil decomposer community as a model system in studying the effects of habitat fragmentation and habitat corridors
2008
Abstract Due to the practical difficulties of experimental study of habitat fragmentation and habitat corridors at the landscape scale, the use of smaller-scale model systems has been offered as a feasible alternative to uncover the ecological phenomena taking place in fragmented environments. In this mini-review, we consider the applicability of the soil decomposer community as such a model system. For the most part, this article is based on the few studies that have explicitly addressed this question by experimental manipulations of the natural habitat of soil decomposer community. However, to broaden the view, we also capitalize upon studies focusing on the effects of isolation and soil …
Effects of two acanthocephalan parasites on the fecundity and pairing status of female Gammarus pulex (Crustacea: Amphipoda)
2002
Acanthocephalan parasites are known to alter the reproductive biology and physiology of their hosts in various ways. In this study we investigated the influence of two acanthocephalan parasites, Pomphorhynchus laevis and Polymorphus minutus, on the fecundity and pairing success of female Gammarus pulex. The results show that P. laevis and P. minutus affect female intermediate host reproduction in different ways. Females infected with P. minutus were totally castrated, whereas those infected with P. laevis only showed reduced fecundity. The oocytes of P. laevis-infected females showed a similar structure to those of uninfected females, although infected females had a higher proportion of ooc…
Genetic Transformation of Serratula tinctoria (Dyer’s Savory) for Ecdysteroid Production
1999
Serratula tinctoria is a perennial plant of the Compositae family with medium-sized, serrated leaves and purple flowers (Loste 1937). This plant, also known as dyer’s savory, is widespread in Europe but with an irregular distribution. Inflorescences (capitula) are purple and are usually unisexual, staminate, or pistillate. In Europe, the flowering period extends from July to September. More than 40 species have been described in Europe, North Africa, and Asia. The plants produce large amounts of secondary metabolites, in particular ecdysteroids at very high concentration in roots (up to 2% dry wt.), in flowers, and in leaves (Bathori et al. 1986; Rudel et al. 1992; Corio-Costet et al. 1993b…
Ardeola, a Scientific Journal of Ornithology: Cooperative Survivorship within the Red Queen Game
2016
Editorial.-- et al.
Coupling agent-based with equation-based models to study spatially explicit megapopulation dynamics
2018
International audience; The incorporation of the spatial heterogeneity of real landscapes into population dynamics remains extremely difficult. We propose combining equation-based modelling (EBM) and agent-based modelling (ABM) to overcome the difficulties classically encountered. ABM facilitates the description of entities that act according to specific rules evolving on various scales. However, a large number of entities may lead to computational difficulties (e.g., for populations of small mammals, such as voles, that can exceed millions of individuals). Here, EBM handles age-structured population growth, and ABM represents the spreading of voles on large scales. Simulations applied to t…
Energetic costs of size and sexual signalling in a wolf spider
1998
A prerequisite for honest handicaps is that there are significant condition–dependent costs in the expression of sexual traits. In the wolf spider Hygrolycosa rubrofasciata (Ohlert), sexual signalling (drumming) is costly in terms of increased mortality. Here we investigated whether this mortality may be caused by increased energy expenditure. During sexual signalling, metabolic rate was 22 times higher than at rest and four times higher than when males were actively moving. Metabolic rate per unit mass was positively related to absolute body mass during sexual signalling but not during other activities. This positive relationship is novel to any studies of metabolic rates. Indeed, it seems…
A morphological and mitochondrial assessment of Apis mellifera from Palermo, Italy
1998
A characterization of the honey bees from western Sicily (Palermo, Italy) is presented. Mor- phological comparisons to A. m. ligustica were made using data taken from honey bee populations from southeastern (Bari) and central (Emilia Romagna) Italy. The honey bees of the Palermo area have distinct morphological differences compared to the mainland honey bees. The mtDNA haplotype common in subspecies within the African lineage of A. mellifera predominated in the Sicilian honey bee samples (13 out of 16). These results suggest both the potential and the desirability to expend efforts to conserve A. m. sicula. © Inra/DIB/AGIB/Elsevier, Paris
Responses of tobacco to elicitins, proteins from Phytophthora spp. eliciting acquired resistance
1994
With the exception of Phytophthora parasitica var. nicotianae (Ppn), the tobacco black-shank causing agent, Phytophthoras give rise to non-host interactions with tobacco. The resulting local hypersensitive response (HR) is accompanied by necrotic spots on the leaves at distance from the infection site [1]. Low molecular weight proteins are excreted by these Phytophthoras, both in planta and in vitro. They form a family of highly homologous holoproteins, called elicitins [2]. Tobacco plants treated with purified elicitins develop necrotic symptoms similar to those induced by the live fungus, and become resistant to further inoculation with Ppn [3]. Elicitin-treated tobacco represent an attra…
Acquired resistance triggered by elicitins in tobacco and other plants
1996
Elicitins are a family of proteins excreted byPhytophthora spp. They exhibit high sequence homology but large net charge differences. They induce necrosis in tobacco plants which then become resistant to the tobacco pathogenPhytophthora parasitica var.nicotianae. In stem-treated plants, resistance was not restricted to the site of elicitin application, but could be demonstrated by petiole inoculation at all levels on the stem. Resistance was already maximum after two days and lasted for at least two weeks. It was effective not only towardsP. p. var.nicotianae infection, but also against the unrelated pathogenSclerotinia sclerotiorum. In contrast to dichloroisonicotinic acid, an artificial i…