Examinando por Autor "Arganda, Sara"

Mostrando 1 - 4 de 4

Insect lifestyle and evolution of brain morphology
(Elsevier, 2020-12) Bouchebti, Sofia; Arganda, Sara
Insect lifestyles are extremely diversified and have important consequences for brain function. Lifestyle determines the resources and information that brains have access to, but also those that are required, to produce adaptive behaviors. Most of the observed adaptations of brain morphology to lifestyle are related to the first stages of sensory information processing (e.g. adaptations to diel habits). However, morphological signatures of lifestyles related to higher order processing of information are more difficult to demonstrate. Co-option of existing neural structures for new behaviors might hinder the detection of morphological changes at a large scale. Current methodological advances will make it possible to investigate finer structural changes and might shed light on whether or not some lifestyles (e.g. eusociality) require morphological adaptations.
Nutrition in extreme food specialists: An illustration using termites
(British Ecological Society, 2018-08-19) Poissonnier, Laure-Anne; Arganda, Sara; Simpson, Stephen J.; Dussutour, Audrey; Buhl, Jerome
1. Recent nutritional ecology theories predict that an organism feeding on a single, highly predictable food should lack the typical active regulation of nutrient balance observed in all other organisms studied so far. It could instead limit itself to controlling the amount of food eaten alone. Such an animal would however be strongly affected by nutrient imbalances. 2. Termites are an ideal model animal to test those predictions. 3. We investigated how the nutritional content of food affected termites’ intake and performance by constraining groups of Nasutitermes exitiosus to artificial diets varying in their macronutrient ratios. 4. We showed that (1) termites, contrary to other insects, did not compensate for nutrient imbalance by adjusting food collection (2) longevity in workers was strongly influenced by carbohydrate intake, while in soldiers it depended almost entirely on the number of workers remaining to feed them (3) tunnelling activity increased with the quantity of food collected and (4) intake had very little influence on lipid and protein termite body contents. 5. We provide evidence that extreme food specialists might have lost the ability to regulate macronutrient intake.
Responses to nutritional challenges in ant colonies
(Elsevier, 2016-01) Bazazi, Sepideh; Arganda, Sara; Moreau, Mathieu; Jeanson, Raphael; Dussutour, Audrey
In social insects, food collection for the entire colony relies on a minority of its workers. How can the colony performance in the choice of resources, the allocation of workers, and the flexibility of food storage strategies emerge from the foraging decisions taken only by a minority? We addressed this question by posing nutritional challenges in the trap-jaw ants Odontomachus hastatus and explored their response in term of survival, foraging behaviour and energy storage. In the first challenge, ants alternated between long periods of confinement to a high protein diet to short periods of confinement to a high carbohydrate diet. In the second challenge, ants alternated between long periods of confinement to a high carbohydrate diet to short periods of confinement to a high protein diet. In the third challenge, ants were given simultaneously the high protein diet and the high carbohydrate diet. First, we showed that (i) mortality increased with protein consumption (ii) short access to a high carbohydrate diet lessened the negative consequence of high protein consumption (iii) ants given a choice of complementary diets regulated intake to minimize mortality. Second, we demonstrated that ants are using an energy saving strategy to overcome challenging nutritional environments. Third, we demonstrated that ants have an extraordinary capacity to regulate the amounts of food entering the nest: (i) at the collective level by allocating more workers to foraging on a high protein diet (ii) at the individual level by collecting more food on a high carbohydrate diet. Our study provides new insights into the strategies used by ants facing nutritional challenges and deepens our understanding of the nutritional ecology of ants, thereby, their vast ecological success.
Sodium pumps adapt spike bursting to stimulus statistics
(Springer Nature, 2007-09-30) Arganda, Sara; Guantes, Raúl; G de Polavieja, Gonzalo
Pump activity is a homeostatic mechanism maintaining ionic gradients. Here we test whether the slow reduction in excitability induced by sodium pump activity seen in many neuronal types can also play a role in neuronal coding. We record intracellularly from a spike bursting sensory neuron in response to naturalistic stimulation using different statistical distributions. We show that the regulation of excitability by sodium pumps is necessary for the neuron to respond differently depending on the statistical context of stimuli. In particular, sodium pump activity allows spike burst sizes and rates to code not for stimulus values per se but their ratio with the standard deviation of the stimulus distribution. Modeling further shows that sodium pumps can be a general mechanism of adaptation to statistics in the time scale of a minute. These results implicate the ubiquitous pump activity in the adaptation to statistics in neural codes.