QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online September 25, 2009
doi: 10.1242/10.1242/dev.037754

This Article Figures Only Full Text Full Text (PDF) Supplementary Material Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Related articles in Development Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Brown, F. D. Articles by De Tomaso, A. W. PubMed PubMed Citation Articles by Brown, F. D. Articles by De Tomaso, A. W. Social Bookmarking                         What's this?

Early lineage specification of long-lived germline precursors in the colonial ascidian Botryllus schlosseri

Federico D. Brown^1,2,3,*,, Stefano Tiozzo^3,*, Michelle M. Roux^3,*, Katherine Ishizuka³, Billie J. Swalla^1,2 and Anthony W. De Tomaso^3,

¹ Biology Department, Center for Developmental Biology, and Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA 98195, USA.
² Friday Harbor Laboratories, University of Washington, Friday Harbor, WA 98250, USA.
³ Molecular, Cellular and Developmental Biology, UC Santa Barbara, Santa Barbara, CA 93106, USA.

Author for correspondence (detomaso{at}lifesci.ucsb.edu)

Accepted 17 August 2009

In many taxa, germline precursors segregate from somatic lineages during embryonic development and are irreversibly committed to gametogenesis. However, in animals that can propagate asexually, germline precursors can originate in adults. Botryllus schlosseri is a colonial ascidian that grows by asexual reproduction, and on a weekly basis regenerates all somatic and germline tissues. Embryonic development in solitary ascidians is the classic example of determinative specification, and we are interested in both the origins and the persistence of stem cells responsible for asexual development in colonial ascidians. In this study, we characterized vasa as a putative marker of germline precursors. We found that maternally deposited vasa mRNA segregates early in development to a posterior lineage of cells, suggesting that germline formation is determinative in colonial ascidians. In adults, vasa expression was observed in the gonads, as well as in a population of mobile cells scattered throughout the open circulatory system, consistent with previous transplantation/reconstitution results. vasa expression was dynamic during asexual development in both fertile and infertile adults, and was also enriched in a population of stem cells. Germline precursors in juveniles could contribute to gamete formation immediately upon transplantation into fertile adults, thus vasa expression is correlated with the potential for gamete formation, which suggests that it is a marker for embryonically specified, long-lived germline progenitors. Transient vasa knockdown did not have obvious effects on germline or somatic development in adult colonies, although it did result in a profound heterochrony, suggesting that vasa might play a homeostatic role in asexual development.

Key words: Asexual reproduction, Botryllus schlosseri, Blastogenesis, Heterochrony, Regeneration, Budding, Colonial ascidian, Coloniality, Germ cells, Germline, Stem cells, vasa

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

Related articles in Development:

Ascidian vasa-llates over (a)sexual development

Development 2009 136: e2005. [Full Text]