Development Genes and Evolution

, Volume 217, Issue 5, pp 403–411

The planarian nanos-like gene Smednos is expressed in germline and eye precursor cells during development and regeneration


  • Mette Handberg-Thorsager
    • Departament de Genètica, Facultat de BiologiaUniversitat de Barcelona
    • Departament de Genètica, Facultat de BiologiaUniversitat de Barcelona
Short Communication

DOI: 10.1007/s00427-007-0146-3

Cite this article as:
Handberg-Thorsager, M. & Saló, E. Dev Genes Evol (2007) 217: 403. doi:10.1007/s00427-007-0146-3


Planarians are highly regenerative organisms with the ability to remake all their cell types, including the germ cells. The germ cells have been suggested to arise from totipotent neoblasts through epigenetic mechanisms. Nanos is a zinc-finger protein with a widely conserved role in the maintenance of germ cell identity. In this work, we describe the expression of a planarian nanos-like gene Smednos in two kinds of precursor cells namely, primordial germ cells and eye precursor cells, during both development and regeneration of the planarian Schmidtea mediterranea. In sexual planarians, Smednos is expressed in presumptive male primordial germ cells of embryos from stage 8 of embryogenesis and throughout development of the male gonads and in the female primordial germ cells of the ovary. Thus, upon hatching, juvenile planarians do possess primordial germ cells. In the asexual strain, Smednos is expressed in presumptive male and female primordial germ cells. During regeneration, Smednos expression is maintained in the primordial germ cells, and new clusters of Smednos-positive cells appear in the regenerated tissue. Remarkably, during the final stages of development (stage 8 of embryogenesis) and during regeneration of the planarian eye, Smednos is expressed in cells surrounding the differentiating eye cells, possibly corresponding to eye precursor cells. Our results suggest that similar genetic mechanisms might be used to control the differentiation of precursor cells during development and regeneration in planarians.


PlanariannanosGerm cellsEyeDevelopmentRegeneration

Supplementary material

427_2007_146_MOESM1_ESM.doc (58 kb)
S1Nucleotide and deduced amino acid sequences of Smednos. The nucleotide sequence consists of four exons. The location of the three introns is indicated with black arrowheads and numbered from I-III. The cysteine and histidine residues of the conserved zinc-finger motifs are shown in bold and the two zinc-finger motifs are underlined in black. The start codon is underlined. The stop codon is indicated with an asterisk. The nucleotides and amino acids (in bold) are numbered in the right margin (DOC 59 kb)
427_2007_146_MOESM2_ESM.doc (107 kb)
S2Alignment of amino acid sequence of the SmedNos zinc-finger motifs and flanking regions with representatives of the Nanos family using ClustalW. The cysteine and histidine residues of the zinc-finger motifs are underlined. The percentage identities are indicated on the right with SmedNos as the consensus sequence. Sequences used for the alignment indicating organism and accession number: Porifera (Ephydatia fluviatilis, PoNOS, BAB19253); Cnidaria (Hydra magnipapillata, CNNOS1, BAB01491; CNNOS2, BAB01492; Podocoryne carnea, PCNOS1, AAU11513; PCNOS2, AAU11514; Nematostella vectensis, NVNOS1, AAY67907; NVNOS2, AAY67908); Platyhelminthes (Schmidtea mediterranea, SmedNos, EF153633; Dugesia japonica, DjNOS, BAD88623.1); Arthropoda (Drosophila melanogaster, DmNos, AAA28715); Annelida (Helobdella robusta, Hro-Nos, AAB63111); Echinodermata (Hemicentrotus pulcherrimus, HpNanos, BAE53723); Chordata (Danio rerio, DanioNos, AAH97090; Xenopus laevis, Xcat-2, CAA51067; Mus musculus, MusNanos1, NP_848508; MusNanos2, NP_918953; MusNanos3, NP_918948; Homo sapiens, HsNanos1, Q8WY41; HsNanos2, P60321; HsNanos3, P60323) (DOC 109 kb)
427_2007_146_MOESM3_ESM.doc (68 kb)
S3Phylogenetic tree obtained by Bayesian inference analysis of the amino acid sequences corresponding to the zinc-finger motifs and flanking regions of representatives of the Nanos family shown in S2. Branch lengths are proportional to numbers of substitutions per site indicated by the scale. Nanos from sponge, PoNOS, was used as the outgroup. SmedNos (highlighted in grey) forms a monophyletic group with Nanos from the protostomes, including Platyhelmintes (DjNOS), Arthropoda (DmNos) and Annelida (Hro-Nos). Accession numbers are indicated in S2 (DOC 69 kb)

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© Springer-Verlag 2007