Format

Send to

Choose Destination
Curr Biol. 2016 Jul 11;26(13):1768-1774. doi: 10.1016/j.cub.2016.05.007. Epub 2016 Jun 30.

The Genome of Intoshia linei Affirms Orthonectids as Highly Simplified Spiralians.

Author information

1
Belozersky Institute for Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119991, Russian Federation; Kharkevich Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow 127994, Russian Federation.
2
Saint Petersburg State University, St. Petersburg 199034, Russian Federation.
3
Belozersky Institute for Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119991, Russian Federation.
4
Belozersky Institute for Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119991, Russian Federation; Kharkevich Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow 127994, Russian Federation. Electronic address: ypanchin@yahoo.com.

Abstract

Orthonectids are rare parasites of marine invertebrates [1] that are commonly treated in textbooks as a taxon of uncertain affinity [2]. Trophic forms of orthonectids reside in the tissues of their hosts as multinucleated plasmodia, generating short-lived, worm-like ciliated female and male organisms that exit into the environment for copulation [3]. These ephemeral males and females are composed of just several hundred somatic cells and are deprived of digestive, circulatory, or excretory systems. Since their discovery in the 19(th) century, the orthonectids were described as organisms with no differentiated cell types and considered as part of Mesozoa, a putative link between multicellular animals and their unicellular relatives. More recently, this view was challenged as the new data suggested that orthonectids are animals that became simplified due to their parasitic way of life [3, 4]. Here, we report the genomic sequence of Intoshia linei, one of about 20 known species of orthonectids. The genomic data confirm recent morphological analysis asserting that orthonectids are members of Spiralia and possess muscular and nervous systems [5]. The 43-Mbp genome of I. linei encodes about 9,000 genes and retains those essential for the development and activity of muscular and nervous systems. The simplification of orthonectid body plan is associated with considerable reduction of metazoan developmental genes, leaving what might be viewed as the minimal gene set necessary to retain critical bilaterian features.

PMID:
27374341
DOI:
10.1016/j.cub.2016.05.007
[Indexed for MEDLINE]
Free full text

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center