Skip to main content

The differential expression of ribosomal 18S RNA paralog genes from the chaetognath Spadella cephaloptera


Chaetognaths constitute a small marine phylum of approximately 120 species. Two classes of both 18S and 28S rRNA gene sequences have been evidenced in this phylum, even though significant intraindividual variation in the sequences of rRNA genes is unusual in animal genomes. These observations led to the hypothesis that this unusual genetic characteristic could play one or more physiological role(s). Using in situ hybridization on the frontal sections of the chaetognath Spadella cephaloptera, we found that the 18S Class I genes are expressed in the whole body, with a strong expression throughout the gut epithelium, whereas the expression of the 18S Class II genes is restricted to the oocytes. Our results could suggest that the paralog products of the 18S Class I genes are probably the “housekeeping” 18S rRNAs, whereas those of class II would only be essential in specific tissues. These results provide support for the idea that each type of 18S paralog is important for specific cellular functions and is under the control of selective factors.



ethylene diamine tetra-acetic acid


messenger ribonucleic acid




optimal cutting temperature


phosphate buffered saline


rough endoplasmic reticulum


ribosomal ribonucleic acid


reverse transcription-polymerase chain reaction


sodium chloride sodium citrate


transfer ribonucleic acid


  1. Casanova, J.-P. Chaetognatha. in: South Atlantic Zooplankton (Boltovskoy, D., Ed.), Backhuys Publishers, Leiden, 1999, 1353–1374.

    Google Scholar 

  2. Feigenbaum, D.L. and Maris, R.C. Feeding in chaetognatha. Oceanogr. Mar. Biol. Ann. Rev. 22 (1984) 343–392.

    Google Scholar 

  3. Matus, D.Q., Copley, R.R., Dunn, C.W., Hejnol, A., Eccleston, H., Halanych, K.M., Martindale, M.Q. and Telford, M.J. Broad taxon and gene sampling indicate that chaetognaths are protostomes. Curr. Biol. 16 (2006) R575–576.

    PubMed  Article  CAS  Google Scholar 

  4. Marletaz, F., Martin, E., Perez, Y., Papillon, D., Caubit, X., Lowe, C.J., Freeman, B., Fasano, L., Dossat, C., Wincker, P., Weissenbach, J. and Le Parco, Y. Chaetognath phylogenomics: a protostome with deuterostome-like development. Curr. Biol. 16 (2006) R577–R578.

    PubMed  Article  CAS  Google Scholar 

  5. Casanova, J.-P., Duvert, M. and Perez, Y. Phylogenetic interest of the chaetognath model. Mésogée 59 (2001) 27–31.

    Google Scholar 

  6. Jean, S., De Jong, L. and Moreau, X. Chaetognaths: a useful model for studying heat shock proteins. Effect of wound healing. J. Exp. Marine Biol. Ecol. 312 (2004) 319–332.

    Article  CAS  Google Scholar 

  7. Takada, N, Goto, T. and Satoh, N. Expression pattern of the Brachyury gene in the arrow worm Paraspadella gotoi (chaetognatha). Genesis 32 (2002) 240–245.

    PubMed  Article  CAS  Google Scholar 

  8. Goto, T. and Yoshida, M. Growth and reproduction of the benthic arrowworm Paraspadella gotoi (Chateognatha) in laboratory culture. Invert. Reprod. Dev. 32 (1997) 201–207.

    Google Scholar 

  9. Prokopowich, C.D., Gregory, T.R. and Crease, T.J. The correlation between rDNA copy number and genome size in eukaryotes. Genome 46 (2003) 48–50.

    PubMed  Article  CAS  Google Scholar 

  10. Rooney, A.P. Mechanisms underlying the evolution and maintenance of functionally heterogeneous 18S rRNA genes in apicomplexans. Mol. Biol. Evol. 21 (2004) 1704–1711.

    PubMed  Article  CAS  Google Scholar 

  11. Ledee, D.R., Seal, D.V. and Byers, T.J. Confirmatory evidence from 18S rRNA gene analysis for in vivo development of propamidine resistance in a temporal series of Acanthamoeba isolates from a patient. Antimicrob. Agents Chemother. 42 (1998) 2144–2145.

    PubMed  CAS  Google Scholar 

  12. Stothard, J.R., Frame, I.A., Carrasco, H.J. and Miles, M.A. Temperature gradient gel electrophoresis (TGGE) analysis of riboprints from Trypanosoma cruzi. Parasitology 117 (1998) 249–253.

    PubMed  Article  CAS  Google Scholar 

  13. Carranza, S, Baguna, J. and Riutort, M. Origin and evolution of paralogous rRNA gene clusters within the flatworm family Dugesiidae (Platyhelminthes, Tricladida). J. Mol. Evol. 49 (1999) 250–259.

    PubMed  Article  CAS  Google Scholar 

  14. Bonnaud, L., Saihi, A. and Boucher-Rodoni, R. Are 28SrDNA and 18SrDNA informative for cephalopod phylogeny? Bull. Mar. 71 (2003) 197–208.

    Google Scholar 

  15. Krieger, J. and Fuerst, P.A. Characterization of nuclear 18S rRNA gene sequence diversity and expression in an individual lake sturgeon (Acipenser fulvescens). J. Appl. Ichthyol. 20 (2004) 433–439.

    Article  CAS  Google Scholar 

  16. Krieger, J., Hett, A.K., Fuerst, P.A., Birstein, V.J. and Ludwig, A. Unusual intraindividual variation of the nuclear 18S rRNA gene is widespread within the acipenseridae. J. Hered. 97 (2006) 218–225.

    PubMed  Article  CAS  Google Scholar 

  17. Papillon, D., Perez, Y., Caubit, X. and Le Parco, Y. Systematics of Chaetognatha under the light of molecular data, using duplicated ribosomal 18S DNA sequences. Mol. Phyl. Evol. 38 (2006) 621–634.

    Article  CAS  Google Scholar 

  18. Telford, M.J. and Holland, P.W.H. Evolution of 28S ribosomal DNA in Chaetognaths: duplicate genes and molecular phylogeny. J. Mol. Evol. 44 (1997) 135–144.

    PubMed  Article  CAS  Google Scholar 

  19. Qari, S.H., Goldman, I.F., Pieniazek, N.J., Collins, W.E. and Lal, A.A. Blood and sporozoite stage-specific small subunit ribosomal RNA-encoding genes of the human malaria parasite Plasmodium vivax. Gene 150 (1994) 43–49.

    PubMed  Article  CAS  Google Scholar 

  20. Thompson, J., van Spaendonk, R.M., Choudhuri, R., Sinden, R.E., Janse, C.J. and Waters, A.P. Heterogeneous ribosome populations are present in Plasmodium berghei during development in its vector. Mol. Microbiol. 31 (1999) 253–360.

    PubMed  Article  CAS  Google Scholar 

  21. Grino, M and Zamora, A.J. An in situ hybridisation histochemistry technique allowing simultaneous visualization by the use of confocal microscopy of three cellular mRNA species in individual neurons. J. Histochem. Cytochem. 46 (1998) 753–759.

    PubMed  CAS  Google Scholar 

  22. Gutell, R.R., Weibser, B., Woese, C.R. and Noller, H.F. Comparative anatomy of 16S-like ribosomal RNA. Prog. Nucleic. Acid. Res. Mol. Biol. 32 (1985) 155–216.

    PubMed  CAS  Article  Google Scholar 

  23. Shinn, G.L. Chaetognaths. in: Microscopic anatomy of invertebrates, Vol. 15, Hemichordates, Chaetognatha and the invertebrate chordates (Harrison, F.W. and Ruppert, E.E., Eds.), Wiley-Liss, New York, 1997, 103–220.

    Google Scholar 

  24. Ghirardelli, E. Some aspects of the biology of the Chaetognaths. Adv. Mar. Biol. 6 (1968) 271–375.

    Google Scholar 

  25. Canipari, R., Pietrolucci, A. and Mangia, F. Increase of total protein synthesis during mouse oocyte growth. J. Reprod. Fertil. 57 (1979) 405–413.

    PubMed  CAS  Article  Google Scholar 

  26. Mercereau-Puijalon, O., Barale, J.C. and Bischoff, E. Three multigene families in Plasmodium parasites: facts and questions. Int. J. Parasitol. 32 (2002) 1323–1344.

    PubMed  Article  CAS  Google Scholar 

  27. Komiya, H., Hasegawa, M. and Takemura, S. Differentiation of oocyte-type and somatic-type 5S ribosomal-RNAs in animals. J. Biochem. 100 (1986) 369–374.

    PubMed  CAS  Google Scholar 

  28. Paillisson, A., Levasseur, A., Gouret, P., Callebaut, I., Bontoux, M., Pontarotti, P. and Monget, P. Bromodomain testis-specific protein is expressed in mouse oocyte and evolves faster than its ubiquitously expressed paralogs BRD2,-3, and-4. Genomics 89 (2007) 215–223.

    PubMed  Article  CAS  Google Scholar 

  29. Yang, J., Su, A.I. and Li, W.H. Gene expression evolves faster in narrowly than in broadly expressed mammalian genes. Mol. Biol. Evol. 22 (2005) 2113–2118.

    PubMed  Article  CAS  Google Scholar 

Download references

Author information

Authors and Affiliations


Corresponding author

Correspondence to Roxane-Marie Barthélémy.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Barthélémy, RM., Grino, M., Pontarotti, P. et al. The differential expression of ribosomal 18S RNA paralog genes from the chaetognath Spadella cephaloptera . Cell Mol Biol Lett 12, 573–583 (2007).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

Key words

  • 18S
  • Chaetognath
  • Spadella cephaloptera
  • In situ hybridization
  • Duplication
  • Expression pattern
  • rRNA paralogs