3D analysis of chitin deposition and ECM interactions during the development of the Drosophila tracheal system in comparison to Parasteatoda tepidariorum, Araneae.

• Applicant: Dr. Bastian-Jesper Klußmann-Fricke
• Subject Area: Evolutionary Cell and Developmental Biology (Zoology)
• Term: from 2018 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 403531010

The tracheal (respiratory) system in arthropods is considered as one of the key adaptations which enabled several arthropod taxa to obtain a terrestrial lifestyle and as a result renders arthropods as the most diverse terrestrial taxon. Within arthropods, however, tracheae evolved not only once but several times independently, i.e. in Arachnida, Myriapoda and Hexapoda. Despite their independent origin, the tracheal systems of most arthropods are remarkable similar, being tubular, cuticle lined respiratory organs which run through the body and conduct oxygen from the exterior to the internal tissues. The cuticle of the tracheae is a highly organized apical extracellular matrix (aECM) formed by several plain horizontal layers. It is composed of the polysaccharide chitin, and a variety of proteins. However, nearly nothing is known about the embryonic development of the tracheal system in other species than Drosophila melanogaster. This implies that a detailed mechanistic study on various aspects of the development of tracheae can only be done in Drosophila before such kind of studies can be extended to other tracheate arthropod taxa. The aim of the proposed project is to contribute to understanding the function of different chitin deposition related genes involved in tracheal morphogenesis in Drosophila. By studying those genes known to play a key role in chitin deposition, I aim to gain new insights into how the aECM controls tube size, cell rearrangements and organization, and how epithelial cells and ECM cross-talk. In order to better understand the developmental processes involved in tracheogenesis, I will analyze the gene expression during tracheal development in Drosophila using various molecular methods like RNA / DNA extraction, in situ hybridization, RNAi and CRISPR / Cas9 in combination with different up-to-date 3D-microscopical techniques. At my chosen host lab of Dr. Marta Llimargas, these techniques are well established. In comparison and to start studies on morphogenesis in other species than Drosophila, these studies will be extended to the spider Parasteatoda tepidariorum, where tracheae clearly evolved independently from insects. Knowledge of these mechanisms would enhance our understanding of morphogenesis and the evolution of organ systems in general and the evolutionary and molecular requirements to evolve such systems in particular.

• DFG Programme: Research Fellowships
• International Connection: Spain
• Host: Dr. Marta Llimargas