A genome wide survey reveals multiple nematocyst-specific genes in Myxozoa

BMC Evolutionary Biology

Paulyn Cartwright¹  Arik Diamant²  Erez Shpirer³ 

[1] Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, USA;National Center for Mariculture, Israel Oceanographic and Limnological Research, Eilat, Israel;School of Zoology, Tel Aviv University, Tel Aviv, Israel

关键词: Cnidaria;    Taxonomically restricted genes;    Polar capsule;    Phylogeny;    Endoparasitism;   

DOI  :  10.1186/s12862-018-1253-7

学科分类：生物科学（综合）

来源: BioMed Central

【 摘 要 】

Myxozoa represents a diverse group of microscopic endoparasites whose life cycle involves two hosts: a vertebrate (usually a fish) and an invertebrate (usually an annelid worm). Despite lacking nearly all distinguishing animal characteristics, given that each life cycle stage consists of no more than a few cells, molecular phylogenetic studies have revealed that myxozoans belong to the phylum Cnidaria, which includes corals, sea anemones, and jellyfish. Myxozoa, however, do possess a polar capsule; an organelle that is homologous to the stinging structure unique to Cnidaria: the nematocyst. Previous studies have identified in Myxozoa a number of protein-coding genes that are specific to nematocytes (the cells producing nematocysts) and thus restricted to Cnidaria. Determining which other genes are also homologous with the myxozoan polar capsule genes could provide insight into both the conservation and changes that occurred during nematocyst evolution in the transition to endoparasitism. Previous studies have examined the phylogeny of two cnidarian-restricted gene families: minicollagens and nematogalectins. Here we identify and characterize seven additional cnidarian-restricted genes in myxozoan genomes using a phylogenetic approach. Four of the seven had never previously been identified as cnidarian-specific and none have been studied in a phylogenetic context. A majority of the proteins appear to be involved in the structure of the nematocyst capsule and tubule. No venom proteins were identified among the cnidarian-restricted genes shared by myxozoans. Given the highly divergent forms that comprise Cnidaria, obtaining insight into the processes underlying their ancient diversification remains challenging. In their evolutionary transition to microscopic endoparasites, myxozoans lost nearly all traces of their cnidarian ancestry, with the one prominent exception being their nematocysts (or polar capsules). Thus nematocysts, and the genes that code for their structure, serve as rich sources of information to support the cnidarian origin of Myxozoa.

【 授权许可】

CC BY