Gene expression profiles of dicyemid life-cycle stages may explain how dispersing larvae locate new hosts

• Published in: Zoological letters Vol. 5; no. 1; p. 32
• Main Authors: Lu, Tsai-Ming, Furuya, Hidetaka, Satoh, Noriyuki
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 13-11-2019; BioMed Central; BMC
• Subjects: Asexual and sexual reproduction; Dicyema japonicum; Differential gene expression; Environmental quality; Gene expression; Genes; Genetic research; Genomes; Genomics; Parasite in octopus renal sacs; RNA; RNA-seq analyses; Two adult and larval forms; Two adult and larval forms; Parasite in octopus renal sacs; Differential gene expression; RNA-seq analyses; Asexual and sexual reproduction; Dicyema japonicum
• ISSN: 2056-306X; 2056-306X
• DOI: 10.1186/s40851-019-0146-y

Metazoans have evolved a great variety of life histories in response to environmental conditions. A unique example is encountered in dicyemid mesozoans. In addition to a highly simplified adult body comprising only ~ 30 cells, dicyemids exhibit a parasitic lifestyle that includes nematogens (asexual reproductive adults), rhombogens (sexual reproductive adults), vermiform larvae generated by nematogens, and infusoriform larvae generated by rhombogens. However, due to the difficulties of observing microscopic endoparasites, the complex life cycle and biological functions of life-cycle stages of dicyemids have remained mysterious. Taking advantage of the recently decoded genome of
, we examined genes that undergird this lifestyle. Using stage-specific gene expression profiles, we found that biological processes associated with molecular transport, developmental regulation, and sensory response are specified at different stages. Together with the expression of potential neurotransmitters, we further suggest that apical cells in infusoriform larva probably serve sensory functions, although dicyemids have no nervous system. Gene expression profiles show that more genes are expressed in free-living infusoriform larvae than in the other three stages, and that some of these genes are likely involved in locating new hosts. These data provide molecular information about the unique lifestyle of dicyemids and illustrate how an extremely simplified endoparasite adapted and retained gene sets and morphological characters to complete its life cycle.
accompanies this paper at 10.1186/s40851-019-0146-y.