論文 - 詳細
| RRC ID | 32368 |
|---|---|
| 著者 | Nozaki H, Yamada TK, Takahashi F, Matsuzaki R, Nakada T. |
| タイトル | New "missing link" genus of the colonial volvocine green algae gives insights into the evolution of oogamy. |
| ジャーナル | BMC Evol Biol |
| Abstract |
BACKGROUND:The evolution of oogamy from isogamy, an important biological event, can be summarized as follows: morphologically similar gametes (isogametes) differentiated into small "male" and large "female" motile gametes during anisogamy, from which immotile female gametes (eggs) evolved. The volvocine green algae represent a model lineage to study this type of sex evolution and show two types of gametic unions: conjugation between isogametes outside the parental colonies (external fertilization during isogamy) and fertilization between small motile gametes (sperm) and large gametes (eggs) inside the female colony (internal fertilization during anisogamy and oogamy). Although recent cultural studies on volvocine algae revealed morphological diversity and molecular genetic data of sexual reproduction, an intermediate type of union between these two gametic unions has not been identified. RESULTS:We identified a novel colonial volvocine genus, Colemanosphaera, which produces bundles of spindle-shaped male gametes through successive divisions of colonial cells. Obligately anisogamous conjugation between male and female motile gametes occurred outside the female colony (external fertilization during anisogamy). This new genus contains 16- or 32-celled spheroidal colonies similar to those of the volvocine genera Yamagishiella and Eudorina. However, Colemanosphaera can be clearly distinguished from these two genera based on its sister phylogenetic position to the enigmatic flattened colonial volvocine Platydorina and external fertilization during anisogamy. Two species of Colemanosphaera were found in a Japanese lake; these species are also distributed in European freshwaters based on a published sequence of an Austrian strain and the original description of Pandorina charkowiensis from Ukraine. CONCLUSIONS:Based on phylogeny and morphological data, this novel genus exhibits a missing link between Platydorina and the typical spheroidal colonial volvocine members such as Pandorina or Yamagishiella. Considering the external obligate anisogamy, oogamy evolution may have been preceded by the transition from external to internal fertilization during anisogamy within the volvocine green algae. |
| 巻・号 | 14(1) |
| ページ | 37 |
| 公開日 | 2014-3-3 |
| DOI | 10.1186/1471-2148-14-37 |
| PII | 1471-2148-14-37 |
| PMID | 24589311 |
| PMC | PMC4015742 |
| MeSH | Biological Evolution* Chlorophyta / classification Chlorophyta / genetics* Chlorophyta / physiology Fertilization Germ Cells / physiology* Molecular Sequence Data Phylogeny Reproduction |
| IF | 3.058 |
| 引用数 | 33 |
| WOS 分野 | EVOLUTIONARY BIOLOGY GENETICS & HEREDITY |
| リソース情報 | |
| 藻類 | NIES-3383 NIES-3384 NIES-3385 NIES-3386 NIES-3387 NIES-3388 NIES-3382 |