Coupling astogenic aging in the colonial tunicate Botryllus schlosseri with the stress protein mortalin

Oshrat Ben-Hamo, Amalia Rosner, Claudette Rabinowitz, Matan Oren, Baruch Rinkevich

Research output: Contribution to journalArticlepeer-review


Botryllus schlosseri, a colonial marine invertebrate, exhibits three generations of short-lived astogenic modules that continuously grow and die throughout the colony's entire lifespan, within week-long repeating budding cycles (blastogenesis), each consisting of four stages (A-D). At stage D, aging is followed by the complete absorption of adult modules (zooids) via a massive apoptotic process. Here we studied in Botryllus the protein mortalin (HSP70s member), a molecule largely known for its association with aging and proliferation. In-situ hybridization and qPCR assays reveal that mortalin follows the cyclic pattern of blastogenesis. Colonies at blastogenic stage D display the highest mortalin levels, and young modules exhibit elevated mortalin levels compared to old modules. Manipulations of mortalin with the specific allosteric inhibitor MKT-077 has led to a decrease in the modules’ growth rate and the development of abnormal somatic/germinal morphologies (primarily in vasculature and in organs such as the endostyle, the stomach and gonads). We therefore propose that mortalin plays a significant role in the astogeny and aging of colonial modules in B. schlosseri, by direct involvement in the regulation of blastogenesis.

Original languageEnglish
Pages (from-to)33-46
Number of pages14
JournalDevelopmental Biology
Issue number1
StatePublished - 1 Jan 2018
Externally publishedYes

Bibliographical note

Funding Information:
We thank Guy Paz and Jacob Douek for their help in various stages of the research, Elizabeth Moiseeva for assisting with histology, Ido Itzhaki and Eitan Reem for help with the statistical analyses, Saurav Misra and Zvi Fishelson for providing the information on MKT-077-mortalin-p53 binding, and Smadar Ben-Tabou de-Leon for helpful remarks. This study was supported by a grant from the Israel Science Foundation (ISF) and partly by a grant from the United States-Israel Binational Science Foundation (BSF), Jerusalem, Israel.

Publisher Copyright:
© 2017 Elsevier Inc.


  • Apoptosis
  • Blastogenesis
  • Botryllus schlosseri
  • GRP75
  • HSP70
  • HSPA9
  • PBP74
  • Senescence
  • Stemness
  • Urochordata

ASJC Scopus subject areas

  • Molecular Biology
  • Developmental Biology
  • Cell Biology


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