Proteomics of the insect larval midgut

Gut proteomics, © MPI CE / Y. Pauchet

Although genomic approaches based on sequencing of cDNA libraries and microarrays can provide information on the identity and abundance of mRNAs produced in the midgut cells, they provide no information on the spatial distribution of proteins in the different compartments of the midgut, and offer no insights into their temporal dynamics afterward, which are exclusively determined by post-translational processes. We are applying proteomic techniques to map the midgut proteome in detail to get more insights on the likely function of this key tissue in insect larvae.
(Yannick Pauchet, Group leader)

 

Relationship between Helicoverpa midgut proteinases and plant proteinase inhibitors

How do plant serine proteinase inhibitors regulate the expression of serine proteinase genes in the insects? Our goal is to get insights into the complex relationship between these plant defenses and their target digestive enzymes present in the caterpillar midgut.
(Suyog Kuwar, PhD student)

Plant cell wall degrading enzymes in herbivorous beetles

Although the presence of plant cell wall degrading enzymes in herbivorous beetles has been known since the late 1990’s, we recently discovered, by using deep sequencing of beetle midgut transcriptomes, that these enzymes are part of relatively large multigene families. Our goal is to characterize these enzymes biochemically and also study their molecular evolution. We are also interested in determining if plants have evolved defenses, such as inhibitors, against these enzymes.
(Yannick Pauchet, Group leader)

Fatty acid nutritional requirements in heliothines

Our goal is to understand how fatty acid intake during the larval stage influences adult performance. We are focusing on an important fatty acid, linolenic acid, which is required for the normal development and metamorphosis of most insect larvae.
(Brent Sørensen, PhD student)

We are also undertaking the exhaustive characterization of the lipase gene family, which is the main family of enzymes responsible for the digestion of these fatty acids.
(Ariadne Tan-Kristanto, Postdoc)

 

Response to environmental stress and resistance to chemical and bio pesticides

Apoptosis, © MPI CE / J. Courtiade

How an organism adapts to environmental stresses, such as infection by pathogens or parasites as well as to xenobiotics, is a complex phenomenon. Cell suicide or apoptosis is often part of this response, but is poorly understood in insects especially in Lepidoptera. Caspases, a type of cysteine proteases, play a central role in apoptosis. We are currently undergoing an exhaustive characterization of this gene family in Lepidoptera.
(Juliette Courtiade, PhD student)

We are also interested in unraveling the mechanisms by which insects become resistant to chemical insecticides. We are focusing on the resistance of Helicoverpa armigera to fenvalerate a pyrethroid-type insecticide.
(Nicole Joußen, Postdoc)

Another aspect of our work focuses on Bacillus thuringiensis Cry toxins. Those toxins represent a class a bioinsecticides that are attractive alternatives to broad-spectrum chemicals. The high specificity, potency, and environmental safety of Cry toxins have led to their wide use in sprayable Bt formulations or transgenic crops. However, evolution of resistance is the main threat to the widespread commercial use of Bt toxins. In this context, we are trying to identify potential candidate genes implicated in resistance to Cry toxins in populations of the Tobacco budworm Heliothis virescens.