The parasitism in Cnidaria: evolution of the genes involved in parasitic life mode, immune response and toxin-like genes

• Grant number: 25/22244-6
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: November 01, 2025
• End date: April 30, 2027
• Field of knowledge: Biological Sciences - Genetics - Animal Genetics
• Principal Investigator: Sónia Cristina da Silva Andrade
• Grantee: Celine Lopes da Silva Santos
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 21/06738-8 - Seascape genetics and comparative genomics: an integrative evolutionary approach in marine invertebrates, AP.BTA.JP2

Abstract

Groups of animals whose species display a wide variety of life strategies, such as Cnidaria, needed to develop different pathways for adaptation to the abiotic and biotic factors. To identify which genetic mechanisms are involved in the maintenance of different life strategies is essential to elucidate the evolution and adaptation of the earliest lineages, which give us a basis to understand the evolutionary process in most recent lineages. The innate immune system and the synthesis of toxins on a large scale through specialized cells are mechanisms that assure the survival of the cnidarians in highly distinct environments. The toxins arsenal in free-life organisms undergoes quick shifts in response to different niches. Usually, the sessile and locomotor behavior are hypothesized to be associated with the emergence, the different profiles and the evolution of the toxins in Cnidaria. On the other hand, the scenario found for pattern recognition receptors (PRRs) repertory in free-life cnidarians involve: a large number of PRRs and expansions of nucleotide-binding oligomerization domain-like receptors (NLRs) and C-type lectins (CTLs) in Anthozoa. The main hypothesis to explain the differences of the immune system repertory between Medusozoa and Anthozoa are associated to the symbiosis, coloniality and sedentary life. Whereas in a parasitic relationship the host provides the energetic demand and protection, but the parasite still needs to deal with the defense strategies of their host, how do immune system and toxin-like proteins work and evolve in parasite cnidarians? The parasitic cnidarians compose the subphylum Endocnidozoa, which include two classes Myxozoa and Polypodiozoa. The parasitism in Myxozoa and Polypodiozoa can have evolved at least, twice independently. Usually, the evolution to the parasitic lifestyle is followed by genetic loss and decrease of the genome size. However, studies evidence the conservation and expansion of gene families that are associated with parasitic activities in Myxozoa. To understand the evolution of the parasitism occurring in earliest diverging animal groups is crucial to elucidate the genetic basis behind this life mode and the transitional process between free and parasitic-life mode. The present study have the following objectives: (1) to identify genes involved in the immune system and the toxin-like proteins in parasite cnidarians of the class Myxozoa and to compare with the profiles of the free-life cnidarians; (2) to understand the evolutionary process acting under genes of the immune system and toxin-like proteins families in parasite cnidarians in comparison with free-life cnidarians and (3) to determine the gene repertory associated with parasitism in Myxozoa and to identify the gene losses, expansion or reduction. (AU)