Identification of genes associated with the circadian clock, localization of clock neurons, and characterization of neurosecretory tissues in Onychophora (velvet worms)

• Applicant: Professor Dr. Georg Mayer
• Subject Area: Systematics and Morphology (Zoology) ; Animal Physiology and Biochemistry
• Term: since 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 408490506

The initial project aimed at clarifying the nomenclature and homology of major brain neuropils in the onychophoran Euperipatoides rowelli, as this topic is important to understanding the evolution of panarthropods (Tardigrada, Onychophora, and Arthropoda). This initiative has been success-ful, as we not only were able to characterize in detail known cerebral structures, but additionally discovered novel regions and neuropils in the onychophoran brain. Furthermore, the initial project opened new perspectives and research questions, which will be pursued in a follow-up project. In the first part of this project, we will focus on identifying and characterizing the molecular mech¬anisms responsible for circadian rhythms in onychophorans. After identifying the major clock genes in E. rowelli and analyzing their potentially rhythmic expression, we will localize the corre¬sponding neurons using in situ hybridization and immunohistochemistry. This will provide insights into the organization and evolution of circadian clocks across panarthropods. In the second part of the project, we will focus on the potential neurosecretory/neuroendocrine tissues in velvet worms. For that, we will investigate the architecture and major molecular components of the so-called dorsal nerve in E. rowelli to address the question of whether this structure is a true nerve or rather a gland. Furthermore, we will analyze the molecular composition (potential neuropep¬tides, small neurotransmitters, and receptors) of the hypocerebral organs, to which presumed neurosecretory functions have been attributed. Using data obtained from differential transcriptom¬ics and different mass spectrometry approaches, such as MALDI TOF and ESI-Q-TOF, we will explore the possible neurosecretory/endocrine roles of the dorsal nerve and the hypocerebral organs and address the question of their potential functional and/or evolutionary relationship to the neurohemal organs and endocrine glands of arthropods.

• DFG Programme: Research Grants