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Immune and METabolic control in intracellular SYMbiosis of insects – IMetSym

Immune and METabolic control in intracellular SYMbiosis of insects (IMetSym)

We investigate insect immune and metabolic regulations potentially involved in endosymbiont maintenance and control. We also explore the effects of endosymbionts on insect immune performance.

General objective of the project

This project focuses on two agronomic pest insects that have different and independent evolutionary and symbiotic histories: the cereal weevil Sitophilus oryzae, and the pea aphid Acyrthosiphon pisum. It is founded at the interface between immunity, metabolism and symbiosis. It aims at deciphering molecular, cellular and metabolic pathways involved in the maintenance and control of insect intracellular symbiotic bacteria. As symbiosis impacts in turn immune and metabolic functions of the host, we also examine the effects of symbiosis on host immune performances. S. oryzae and A. pisum are two emerging models in genomics that have benefited recently of significant advances on genome and transcriptome sequencing and annotation, as well of new genetic tools, cellular and experimental facilities that have proved their feasibility.

The three teams involved have a long-standing expertise in the study of the molecular, cellular and metabolic bases of insect endosymbiosis. Partner 1 is at the forefront of research deciphering immune interactions and the molecular dialogue between weevils and their endosymbionts, partner 2 has a long experience in insect cellular immune defenses and has recently developed exciting cellular tools on the aphid model, and partner 3 has a long-standing knowledge on host-symbiont metabolic exchanges, and uses a system biology approach, including artificial nutrition, biochemistry and transcriptomic analyses, functional biology and metabolic modeling mainly on aphids.

We have shown at first time that insects modulate their symbiont load and adjust it to their physiological needs. Indeed, weevils drastically multiply their endosymbionts following adult emergence, which help them to build up rapidly their cuticle, then they recycle them completely by activating autophagy and apoptosis (Vigneron et al., Current Biology, 2014)

The project is progressing normally. At mid-term, post-doctoral students will be recruited, which will boost the project in temrs of result and paper production. The equipment essential to the progress of work has been chosen (funded through the budget of the ANR) and the purchase has been finalized.

Since the beginning of the IMetSym project, two publications has been accepted, including one article in Current Biology journal. Moreover, four papers are submitted.

The field of microbial symbiosis has achieved astonishing advances during the past two decades demonstrating its universality and significance in multicellular life and evolution. For example, it has been estimated that microbes in the human body collectively make up to 100 trillion cells. The majority resides in the gut and has a profound influence on human nutrition and physiology. Accordingly, disequilibrium of the gut microbiome has been shown to be often associated with immune-related diseases.
Insects, such as Drosophila, are developing models to decipher microbial interactions. Insights can also be expected from the study of insects thriving on nutritionally poor habitats that have evolved long-term mutualistic relationships with one or a few endosymbiotic bacteria. These bacteria are vertically transmitted and are housed within specific host cells, the bacteriocytes that are thought to isolate endosymbionts and protect them against a systemic host immune response. However, whilst physiological and evolutionary features of these insect associations have been investigated in detail over the past decades, current knowledge of specific host factors leading to endosymbiont tolerance, localization, transmission and control by the host remains limited. It is suggested that components of host immunity are in a constant struggle between managing beneficial symbionts while turning on host defenses to prevent pathogenic infections.
Here, we will investigate insect immune and metabolic regulations potentially involved in endosymbiont maintenance and control, as well as explore the effects of endosymbionts on insect immune performance. Our focus will be on the comparison of two agronomic pest insects that have different and independent evolutionary and symbiotic histories. The cereal weevil Sitophilus oryzae, a holometabolous insect, exhibits an evolutionary recent symbiosis with strictly one primary endosymbiont, while the pea aphid Acyrthosiphon pisum, a hemimetabolous insect, lives a relatively old association with one primary and several secondary endosymbionts. These insects are expected to become emerging models in functional genomics thanks to the recent initiatives in genome and transcriptome sequencing and to the development of new genetic, and cellular experimental tools. We will use a multidisciplinary approach to understand the links between humoral immune responses, hemocyte and bacteriocyte immune function and specificity, and metabolism, so as to decipher the role of these different players in endosymbiosis homeostasis. We expect from this project to open new insights into insect symbiosis establishment and maintenance and to identify potential gene targets useful for the development of new strategies for pest insects control and management.

Project coordinator

Monsieur Abdelaziz HEDDI (UMR203 Biologie Fonctionnelle Insectes et Interactions (BF2I), équipe Symbioses et Signalisations Immunitaires (SymSIm))

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

ISA-ESIM INRA-PACA Centre de Sophia Antipolis, UMR Sophia Agrobiotech, INRA 1355, CNRS 7254, Université Nice Sophia Antipolis - ESIM team
SymT, INSA Lyon, INRA UMR203 Biologie Fonctionnelle Insectes et Interactions (BF2I), équipe Symbioses et Interactions Trophiques (SymT)
SImSym, INSA Lyon, INRA UMR203 Biologie Fonctionnelle Insectes et Interactions (BF2I), équipe Symbioses et Signalisations Immunitaires (SymSIm)

Help of the ANR 423,890 euros
Beginning and duration of the scientific project: December 2013 - 42 Months

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