Advantage or Disadvantage: Is Asexual Reproduction Beneficial to Survival of the Tunicate, Polyandrocarpa misakiensis?
スポンサーリンク
概要
- 論文の詳細を見る
It has been believed that clonal propagation by asexual reproduction has serious disadvantages for long-term survival, because asexual reproduction seems not to remove harmful mutations, it seems not to give rise to genetic variations upon which evolution depends and it seems not to reset cell aging. In this article, we re-consider those arguments, by reviewing asexual reproduction of the tunicate, Polyandrocarpa misakiensis. Tracer experiments of bud formation and growth using morphological and chimeric phenotypes showed that the parental epithelial tissues surrounding the bud primordium do not enter the growing bud. It is possible, therefore, to assume that budding involves the purge of a large number of parental somatic cells and tissues. Unlike sexuals, asexuals do not carry out meiotic recombination nor gene shuffling that are two major sources of genetic variation, but we can show that in P. misakiensis at least two genes have significant redundancy and genetic variation even in a clonal colony. Telomerase expressed in germlines is thought to reset the molecular clock executed by telomere shortening. In our Polyandrocarpa cDNA projects, four out of about 2,000 cDNAs examined were matched with retroviral reverse transcriptase that is the catalytic subunit of telomerase, suggesting that telomerase might work in asexual reproduction. In P. misakiensis, dedifferentiation system is used to make new asexual generations. TC14 lectin plays an important role in the maintenance of multipotent but differentiated state of the formative tissue. It is antagonized by tunicate serine protease (TRAMP) that has striking mitogenic and dedifferentiation-inducing activities on the multipotent cells. This system would serve to delay aging of somatic cells. In conclusion, empirical arguments that asexual reproduction is disadvantageous to long-term life do not appear to be tenable to budding of P. misakiensis.
- 社団法人日本動物学会の論文
- 2000-04-10
著者
-
Kawamura Kazuo
Laboratory Of Cellular And Molecular Biotechnology Faculty Of Science Kochi University
-
FUJIWARA Shigeki
Laboratory of Cellular and Molecular Biotechnology, Faculty of Science, Kochi University
-
Fujiwara Shigeki
Laboratory Of Cellular And Molecular Biotechnology Faculty Of Science Kochi University
-
Kawamura Kazuo
Laboratory of Cellular and Molecular Biotechnology, Faculty of Science, Kochi University
関連論文
- The Structural Organization of Ascidian Halocynthia roretzi Troponin I Genes
- Structure of a cDNA for Ciona Cytochrome b_5 and the Ubiquitous Expression of mRNA in Embryonic Tissues
- Phospholipids and Their Derivatives as Mitogen and Motogen of Budding Tunicates
- Characterization of Cytochrome b_5 in the Ascidian Polyandrocarpa misakiensis and Budding-Specific Expression^1
- Functional retinoid receptors in budding ascidians
- Serine Protes\ase Inhibitors Expressed in the Process of Budding of Tunicates as Revealed by EST Analysis
- Molecular collaborations between serpins and trefoil factor promote endodermal cell growth and gastrointestinal differentiation in budding tunicates
- Establishment of Cell Lines from Multipotent Epithelial Sheet in the Budding Tunicate, Polyandrocarpa misakiensis
- Piwi-expressing hemoblasts serve as germline stem cells during postembryonic germ cell specification in colonial ascidian, Botryllus primigenus
- Postembryonic epigenesis of Vasa-positive germ cells from aggregated hemoblasts in the colonial ascidian, Botryllus primigenus
- Acquisition of Retinoic Acid Signaling Pathway and Innovation of the Chordate Body Plan
- In Vitro Culture of Mesenchymal Lineage Cells Established from the Colonial Tunicate Botryllus primigenus
- Advantage or Disadvantage: Is Asexual Reproduction Beneficial to Survival of the Tunicate, Polyandrocarpa misakiensis?
- REGULATION OF ZICL TRANSCRIPTION IN THE CIONA INTESTINALIS EMBRYO(Genetics,Abstracts of papers presented at the 75^ Annual Meeting of the Zoological Society of Japan)
- POSTEMBRYONIC EPIGENESIS OF GERMLIME CELLS FROM AGGREGATED HAEMOBLASTS IN BUDDING TUNICATES
- Multipotent epithelial cells in the process of regeneration and asexual reproduction in colonial tunicates