RAPID ASSEMBLY OF A WOUND PLUG: STAGE ONE OF A TWO‐STAGE WOUND REPAIR MECHANISM IN THE GIANT UNICELLULAR CHLOROPHYTE DASYCLADUS VERMICULARIS (CHLOROPHYCEAE)¹

Abstract

Upon injury, selected coenocytic algae are capable of forming temporary wound plugs to prevent detrimental cytoplasmic loss. Wound plugs of Dasycladus vermicularis ([Scropoli] Krasser) were harvested 5 min post-injury and dried. The plug material contained 94% water and can be considered a hydrogel. The gel plug extended several millimeters from the cut end and filled the space inside the cell wall, which resulted from cytoplasmic retraction. Total organic carbon included 55% sugars, 5%-15% protein, and 0.18% lipids. The major sugars were glucose, galactose, mannose, and galacturonic acid. Fluorescein isothiocyanate-lectins specific for these sugars were localized around the plug matrix. Sulfur content calculated as sulfate corresponded to 17% of the carbohydrate by weight, and sulfated material was detected in plugs by Alcian Blue staining. Formation of the initial plug occurred within 1 min of injury and was not significantly perturbed by the addition of ionic, antioxidant, or chelating agents to the seawater medium. However, addition of exogenous D( þ )-galactose and D( þ )-glucose prevented formation of the nascent gel plug. Wound plugs that were allowed to form from 10 min up until 24 h post-injury were isolated and incubated with selected biochemical probes to identify the biochemical processes involved in plug formation. The operative strategy in Dasycladus to prevent ''cytoplasmic hemorrhage'' required availability of sequestered carbohydrate and lectin precursor components throughout the thallus for plug assembly. Once the initial assembly had commenced, additional biochemical interactions were initiated (as a function of time) to promote structural integrity.

Purification and characterization of a lectin, BPL-3, from the marine green alga Bryopsis plumosa

“…Algal lectins are known to function in the sexual reproduction (Maier and Müller 1986;Kim et al 2007) and wound-healing events (Kim et al 1995;Ross et al 2005). Recently, the medical use of algal lectins has been studied extensively, and some lectins exhibiting high anti-HIV (Sato et al 2007;Li et al 2008;Ziółkowska and Wlodawer 2006) and antibiotic activities (Liao et al 2003) have been isolated.…”

Molecular characterization of a lectin, BPL-4, from the marine green alga Bryopsis plumosa (Chlorophyta)

“…The difference of amino acids in binding domains of these lectins may explain the difference of sugar binding specificity and hemagglutinating activity between BPL-3 and other H type lectins (Han et al 2011). Accumulating evidences show that algal lectins are involved in many biological processes, including wound response and sexual reproduction (Maier and Müller 1986, Kim et al 1995, Ross et al 2005, Yoon et al 2008. However, the evolutionary origin of algal lectins is still in question.…”

Eine Desulfatierungs‐Oxidations‐Kaskade aktiviert auf Cumarin basierende Vernetzer in der Wundverschlussreaktion der einzelligen Makroalge Dasycladus vermicularis

“…Der zeitliche Ablauf des Wundheilungsprozesses in dieser Alge wurde bereits detailliert beschrieben. [6,7] Nach einer anfänglich schnellen Gelbildung folgt eine verzögerte Verhärtung und Braunfärbung. Dieser Ablauf führt insgesamt zur Bildung eines starren Biopolymers (Abbildung 1).…”

“…Da Hydroxycumarine leicht oxidiert werden können, [12] haben wir die Hypothese überprüft, dass THyC in der verwundeten Alge direkt weiter umgewandelt wird. Reaktive Sauerstoffspezies, die bereits in verwundeter D. vermicularis nachgewiesen wurden, [7] könnten als Oxidationsmittel für THyC dienen. Wenn man die Kinetiken der H 2 O 2 -Produktion [7] und der DHyCS-Umwandlung vergleicht, fällt auf, dass erst nach der vollständi-gen Umwandlung von DHyCS das Oxidationsmittel detektiert werden kann (siehe die Hintergrundinformationen [13,14] Um weitere Beweise für eine Beteiligung von THyC an der oxidativen Biopolymerisation zu liefern, wurde der Metabolit zusammen mit HRP und H 2 O 2 in Gegenwart des Modellproteins a-Lactalbumin inkubiert.…”