First report on chitinous holdfast in sponges (Porifera)

Hermann Ehrlich, Oksana V. Kaluzhnaya, Mikhail V. Tsurkan, Alexander Ereskovsky, Konstantin R. Tabachnick, Micha Ilan, Allison Stelling, Roberta Galli, Olga V. Petrova, Serguei V. Nekipelov, Victor N. Sivkov, Denis Vyalikh, René Born, Thomas Behm, Andre Ehrlich, Lubov I. Chernogor, Sergei Belikov, Dorte Janussen, Vasilii V. Bazhenov, Gert Wörheide

Research output: Contribution to journalArticlepeer-review

Abstract

A holdfast is a root- or basal plate-like structure of principal importance that anchors aquatic sessile organisms, including sponges, to hard substrates. There is to date little information about the nature and origin of sponges' holdfasts in both marine and freshwater environments. This work, to our knowledge, demonstrates for the first time that chitin is an important structural component within holdfasts of the endemic freshwater demosponge Lubomirskia baicalensis. Using a variety of techniques (near-edge X-ray absorption fine structure, Raman, electrospray ionization mas spectrometry, Morgan-Elson assayand Cal-cofluor White staining), we show that chitin from the sponge holdfast is much closer to a-chitin than to b-chitin. Most of the three-dimensional fibrous skeleton of this sponge consists of spicule-containing proteinaceous spongin. Intriguingly, the chitinous holdfast is not spongin-based, and is ontogenetically the oldest part of the sponge body. Sequencing revealed the presence of four previously unde-scribed genes encoding chitin synthases in the L. baicalensis sponge. This discovery of chitin within freshwater sponge holdfasts highlights the novel and specific functions of this biopolymer within these ancient sessile invertebrates.

Original languageEnglish
Article number20130598
JournalProceedings of the Royal Society B: Biological Sciences
Volume280
Issue number1762
DOIs
StatePublished - 7 Jul 2013

Keywords

  • Chitin
  • Endemic sponges
  • Holdfast
  • Porifera

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