Wound‐healing in Vaucheria longicaulis Hoppaugh var. macounii Blum.

Abstract

SUMMARY The sequence of events leading to wound‐healing and resumption of growth are studied by light microscopy including the use of differential interference contrast optics in Vaucheria longicaulis Hoppaugh var. macounii Blum. Wound‐healing has been divided into four stages. In stage 1, a wound‐healing vesicle is rapidly extruded from the wound site. Loss of turgor pressure, as observed by the appearance of plasmolysis, is seen along the length of the filament. In stage 2, the wound‐healing vesicle is sealed‐off from the filament. Organelles then accumulate at the barrier created by the sealing‐off process. This is followed by chloroplast retraction from and return to the wound site, concurrent with the restoration of turgor pressure in late stage 2. In stage 3 chloroplasts again retract from and return to the wound site, in preparation for stage 4 that finally leads to the resumption of growth on the part of the healed filament. The effect of wound healing on organelle distribution has been studied with the use of selective fiuorochromes. The distribution of nuclei, identified by DAPI staining, remains largely unchanged after wounding. Mitochondria and probable lipid bodies (designated RBIs) are identified by staining with DiOC6 and Rhodamine B, respectively. Their presence in the wound‐healing vesicle cytoplasm and accumulation along the wound site points to the existence of an efficient mechanism of ATP synthesis in support of the energy requirements associated with the healing process. CTC fluorescence along the wound site and wound vesicle cytoplasm suggests that Ca2+‐based exocytosis is important in both wound‐healing vesicle expansion and its sealing‐off from the filament.

Mitochondrial Dynamics in Red Algae. 3. Filament Apices in Colaconemacaespitosum (Acrochaetiales) and Antithamnion cruciatum (Ceramiales)

“…First, red algal mitochondria label similar to other algae (e.g., Chida and Ueda 1986;Hatano and Ueda 1988;Hayashi and Ueda 1989;Tornbom and Oliveira 1993), although the red algal wall seems more difficult for these fluorescent stains to penetrate than in other algae. This problem was previously noted with entry of other labeling agents (Garbary and McDonald 1998), and was overcome with the use of concentrated seawater or glucuronidase.…”

Wound‐healing in Vaucheria longicaulis Hoppaugh var. macounii Blum.

“…However, both the pattern and speed of movement of the organelles are different from those in uncut filaments. These changes are largely coincident with the development of plasmolysis along the length of the wounded filaments (Tornbom & Oliveira, 1993). Initially, chloroplast movement stops as plasmolysis increases.…”

“…Cut filaments : wound region. The sequence of events characteristic of stages 1 and 2 of wound healing (Tornbom & Oliveira, 1993) remain largely unaltered by Cytochalasin B. However, the woundhealing process takes approximately 35 times longer than in untreated cut filaments.…”

“…macounii selected for microscopical studies were removed from actively growing cultures, and excised while immersed in half-strength Instant Ocean medium. Observations of wound healing were conducted as described in the companion study (Tornbom & Oliveira, 1993).…”

“…Vaucheria longicaulis exhibits the capacity to studies have been conducted in coenocytic cells heal large transverse wounds, and this wound- (Menzel, 1988). This is due to the fact that being healing process is the object of the companion study large, single-celled organisms, the occurrence of (Tornbom & Oliveira, 1993). However, most of the healing at the cellular, compared to the tissue level as studies on wound healing provide little information in multicellular organisms, is critical for their on the dynamic reorganization and participation of survival (Menzel, 1988;Ott, 1992).…”