Sensory evolution in the darkness: study on the chemosensory system of subterranean planaria Girardia multidiverticulata (Platyhelminthes, Tricladida)

• Grant number: 23/03134-0
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: March 01, 2024
• End date: May 31, 2027
• Field of knowledge: Biological Sciences - Zoology - Morphology of Recent Groups
• Principal Investigator: Federico David Brown Almeida
• Grantee: Carlos Henrique Zanello Talarico
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Animals with less developed visual abilities, like many organisms that inhabit the subterranean environment, generally rely on chemotaxis to find food. This is the case of the planaria, a model organism that exhibits chemotactic behavior. Recently, a new species of planaria (Girardia multidiverticulata) was described, which represents the first obligate cave-dwelling species in South America that presents specialized characters for living in these environments, called troglomorphisms. Troglomorphisms may involve enhancement of the non-visual sensory system to compensate for the regression of eyes or loss of the phototactic system. In addition to the auricles of flatworms, other regions such as the oropharynx and hair cells in the epidermis throughout the body could be involved in chemoreception. The cave planarian G. multidiverticulata represents an ideal model to study how the absence of light can influence the evolution of the chemosensory system. The objectives of this project are: 1) Identify the planarian chemotaxis system. Understand which body regions, tissues and cells of planarians are involved in chemotaxis through behavioral, morphological and histological analyses comparing two species G. multidiverticulata and the epigean species of the same genus G. tigrina.; 2) Understand gene regulation (expression and function) during development of the chemosensory system in studies of regeneration or dissection of different cell types (epidermis or neuronal cells related to chemotaxis) using transcriptomic analyses and gene knockdowns by RNAi. By comparing surface vs. cave planarians, we expect to elucidate the chemosensory differences among these species, and understand the selective pressures acting on them. With this project, we hope to contribute to the general understanding of the mechanisms related to non-visual sensory systems in a challenging environment such as caves.