Specific alterations in riboproteomes composition of isonicotinic acid treated arabidopsis seedlings

Plants have developed strategies to deal with the great variety of challenges they are exposed to. Among them, common targets are the regulation of transcription and translation to finely modulate protein levels during both biotic and abiotic stresses. Increasing evidence suggests that ribosomes are highly adaptable modular supramolecular structures which remodel to adapt to stresses. Each Arabidopsis thaliana ribosome consists of approximately 81 distinct ribosomal proteins (RPs), each of which is encoded by two to seven genes. To investigate the identity of ribosomal proteins of the small subunit (RPS) and of the large subunit (RPL) as well as ribosomes-associated proteins, we analysed by LC/MS/MS immunopurified ribosomes from A. thaliana leaves treated with isonicotinic acid (INA), an inducer of plant innate immunity. We quantified a total of 2084 proteins. 165 ribosome-associated proteins showed increased abundance while 52 were less abundant. Of the 52 identified RPS (from a possibility of 104 encoding genes), 15 were deregulated. Similarly, from the 148 possible RPL, 80 were detected and 9 were deregulated. Our results revealed potential candidates involved in innate immunity that could be interesting targets for functional genomic studies

Individual rules for trail pattern formation in Argentine ants (Linepithema humile)

We studied the formation of trail patterns by Argentine ants exploring an empty arena. Using a novel imaging and analysis technique we estimated pheromone concentrations at all spatial positions in the experimental arena and at different times. Then we derived the response function of individual ants to pheromone concentrations by looking at correlations between concentrations and changes in speed or direction of the ants. Ants were found to turn in response to local pheromone concentrations, while their speed was largely unaffected by these concentrations. Ants did not integrate pheromone concentrations over time, with the concentration of pheromone in a 1 cm radius in front of the ant determining the turning angle. The response to pheromone was found to follow a Weber's Law, such that the difference between quantities of pheromone on the two sides of the ant divided by their sum determines the magnitude of the turning angle. This proportional response is in apparent contradiction with the well-established non-linear choice function used in the literature to model the results of binary bridge experiments in ant colonies (Deneubourg et al. 1990). However, agent based simulations implementing the Weber's Law response function led to the formation of trails and reproduced results reported in the literature. We show analytically that a sigmoidal response, analogous to that in the classical Deneubourg model for collective decision making, can be derived from the individual Weber-type response to pheromone concentrations that we have established in our experiments when directional noise around the preferred direction of movement of the ants is assumed.Comment: final version, 9 figures, submitted to Plos Computational Biology (accepted

In memoriam Jacques Gervet (1934–2018)

International audienc

Comparative study of resistance to heat in two species of leaf-cutting ants

International audienc

Nonrandom search geometry in subterranean termites

[Extract] Studies of the organization of search in ants suggest that individual and colonylevel patterns are related to foraging ecology and may be adaptive [1, 2]. The organization of search in termites has received far less attention, in part because of their cryptic, subterranean foraging habits. Search in subterranean termites involves the construction of a gallery system, a series of branching tunnels in the soil that brings termites into contact with food. The organization of the gallery system might reflect the efficiency of colony search. In this paper we describe the nonrandom colony- level search pattern of the subterranean termite Reticulitermes ftavipes (Kollar), and suggest that it may be organized to minimize search redundancy

Self-Organization Patterns in Wasp and Open-Source Communities

International audienc

From individual to collective displacements in heterogeneous environments.

Animal displacement plays a central role in many ecological questions. It can be interpreted as a combination of components that only depend on the animal (for example a random walk) and external influences given by the heterogeneity of the environment. Here we treat the case where animals switch between random walks in a homogeneous 2D environment and its 1D boundary, combined with a tendency for wall-following behaviour (thigmotactism) that is treated as a Markovian process. In the first part we use mesoscopic techniques to derive from these assumptions a set of partial differential equations (PDE) with specific boundary conditions and parameters that are directly given by the individual displacement parameters. All assumptions and approximations made during this derivation are rigorously validated for the case of exploratory behaviour of the ant Messor sanctus. These PDE predict that the stationary density ratio between the 2D (centre) and 1D (border) environment only depends on the thigmotactic component, not on the size of the centre or border areas. In the second part we test this prediction with the same exploratory behaviour of M. sanctus, in particular when many ants move around simultaneously and may interact directly or indirectly. The prediction holds when there is a low degree of heterogeneity (simple square arena with straight borders), the collective behaviour is "simply" the sum of the individual behaviours. But this prediction breaks down when heterogeneity increases (obstacles inside the arena) due to the emergence of pheromone trails. Our approach may be applied to study the effects of animal displacement in any environment where the animals are confronted with an alternation of 2D space and 1D borders as for example in fragmented landscapes