Table 1.
Primers used for PCR amplification in this study.
Table 2.
Summary of the response to thallus severing.
Fig 1.
Budding, rhizoid formation, and sporulation are the major responses to injury.
(A) Number of macroalgal species that showed the indicated response. The numbers of red, brown, and green algae are indicated by their colours. (B) Rhizoid formation at the basal cut site in Myelophycus simplex (Harvey) Papenfuss. (C) Budding at the cut site of Gelidium elegans. The rightmost panel is a section image of the blue dotted line in the second panel. Buds appeared in the inner part of the cut surface. (D) Buds appeared at the edge of the cut surface in Gracilariopsis chorda (Holmes) Ohmi. (E) Bud and rhizoid formation after cutting of Bryopsis sp. (F) Bud and rhizoid formation after cutting of Symphyocladia linearis (Okamura) Falkenberg. (G) Sporulation in Cladophora albida. Within 24 h after injury, spores were formed and released from the thalli. White arrowhead, bud; yellow arrowhead, rhizoid; blue arrowhead, pore through which spores are released.
Fig 2.
Tip growth, nuclear division, and septation in Colaconema codicola.
(A) Colaconema codicola was isolated from the surface of Codium fragile (top). Colaconema codicola was successfully cultured in the absence of Codium fragile in the laboratory (bottom). (B) Rhizoid formation upon severing. (C) Time-lapse imaging of the nuclei (yellow arrows) of a regenerating cell (rhizoid). The cell next to the injured cell underwent a nuclear division followed by septation (arrowhead) during tip growth. Mitotic chromosome condensation was observed at 540 min, and sister chromatid segregation was complete by 630 min (a sister nucleus is out of focus). (D) Schematic presentation of the injury response in Colaconema codicola. Mitotic nuclei are indicated in green.
Fig 3.
Tip growth, synchronised multinuclear division, and septation in Dasya sp.
(A) Dasya sp. (B) Formation of buds (white arrowheads) and rhizoids (yellow arrowheads) at the apical and basal cut sites, respectively. (C) Time-lapse imaging of the nuclei of a regenerating cell (rhizoid). The cell next to the injured cell underwent two rounds of nuclear divisions and septation during tip growth. Yellow and blue arrows indicate mitotic chromosome condensation and septation, respectively. (D) Schematic presentation of the injury response in Dasya sp. Mitotic nuclei are indicated in green.
Fig 4.
Tip growth, unsynchronised multinuclear division, and septation in Cladophora albida.
(A) Formation of rhizoids (yellow arrowhead) at the basal cut site. (B, C) Time-lapse imaging of the nuclei of a regenerating cell (rhizoid). The cell next to the injured cell showed tip growth (tips are indicated by open white arrows). (B) In the majority of cases, nuclear division was undetectable, whereas the vacuole developed and occupied the cytoplasm. (C) In other cases, the growing cell underwent nuclear division, not in a synchronous manner, followed by single septation during tip growth. Branching is also observed at the end (white arrow). Green, yellow, and magenta arrows indicate mitotic chromosome condensation, whereas septation is indicated by filled white arrowheads. (D) Schematic presentation of the injury response in Cladophora albida. Mitotic nuclei are indicated in green.
Fig 5.
Cell repair, protrusion, tip growth, and nuclear migration in Codium fragile.
(A) Codium fragile. Close-up of the thalli that are composed of closely packed utricles (top right). A single utricle (bottom left, white arrow) with an incomplete septum (blue arrow) and tubular branches (white arrowhead). Fourteen days after isolation, the utricles withered (white open arrow), and the tubular branches grew to form filamentous thalli. (B) Formation of rhizoids (left arrow) and new branches (right arrow) after severing. (C) Time-lapse imaging of nuclei (dyed with Hoechst 33342) (top) and plastids that are visualized by transmission light microscopy (bottom). The cut-repaired site is located on the right (indicated by a strong, linear Hoechst signal). The orange arrow indicates the emergence of a bud. Blue arrows indicate incomplete septation. (D) Schematic presentation of the injury response of Codium fragile.