The characean internodal cell as a model system for studying wound healing

Abstract

SummaryThis work describes the characean internodal cell as a model system for the study of wound healing and compares wounds induced by certain chemicals and UV irradiation with wounds occurring in the natural environment. We review the existing literature and define three types of wound response: (1) cortical window formation characterised by disassembly of microtubules, transient inhibition of actin-dependent cytoplasmic streaming and chloroplast detachment, (2) fibrillar wound walls characterised by exocytosis of vesicles carrying wall polysaccharides and membrane-bound cellulose synthase complexes coupled with endocytosis of surplus membrane and (3) amorphous, callose-and membrane-containing wound walls characterised by exocytosis of vesicles and endoplasmic reticulum cisternae in the absence of membrane recycling. We hypothesize that these three wound responses reflect the extent of damage, probably Ca 2+ influx, and that the secretion of Ca 2+ -loaded endoplasmic reticulum cisternae is an emergency reaction in case of severe Ca 2+ load. Microtubules are not required for wound healing but their disassembly could have a signalling function. Transient reorganisation of the actin cytoskeleton into a meshwork of randomly oriented filaments is required for the migration of wound wall forming organelles, just as occurs in tip-growing plant cells. New data presented in this study show that during the deposition of an amorphous wound wall numerous actin rings are present, which may indicate specific ion fluxes and/or a storage form for actin. In addition, we present new evidence for the exocytosis of FM1-43-stained organelles, putative endosomes, required for plasma membrane repair during wound healing. Finally, we show that quickly growing fibrillar wound walls, even

The Evolutionary Origin of a Terrestrial Flora

“…The deposition of callose at the tip of developing rhizoids in Spirogyra suggests developmental similarity to pollen tubes and root hairs in flowering plants [74]. Callose is broadly distributed among the charophytes and other algae, and seems often to be associated with tip growth [75][76][77].…”

Photosynthesis-dependent formation of convoluted plasma membrane domains in Chara internodal cells is independent of chloroplast position

“…Fluorescent plasma membrane dyes like FM1-43 accumulate in the membranous tubules of charasomes and can therefore be used for visualization of charasomes in living cells (Schmoelzer et al 2011 ). The FM-dyes also stain membrane- and callose-containing amorphous wound walls deposited after injury or in senescent cells (Foissner and Wasteneys 2012 ; see below). In order to exclude the possibility that small wound walls were mistaken for charasomes, we used electron microscopy and/or co-labeling with sirofluor, a callose-specific fluorescent stain which labels the wound walls only (see Klima and Foissner 2008 ).…”

“…This treatment was sufficient to cause rounding up of chloroplasts and to temporarily impede streaming in the irradiated zone. Longer irradiation times which lead to the deposition of a wound wall (Foissner and Wasteneys 2012 ) were not applied. For recovery and for charasome formation, cells were placed into Petri dishes containing AFW or a mixture of AFW and modified Forsberg medium and exposed to light provided by fluorescent lamps with an intensity of about 5 μEinstein m −2 s −1 .…”

“…The internodal cells of the characean algae may become up to 20 cm long. They have been a widely used model system in plant biology and are useful for studying various aspects of cellular dynamics and the cytoskeleton (Foissner and Wasteneys 2012 ; Shimmen and Yokota 2004 ). They are also well suited for the study of transmembrane transport and plasma membrane domains (Beilby and Bisson 2012 ; Beilby and Casanova 2014 ; Foissner and Wasteneys 2014 ; Volkov 2006 ).…”

The role of charophytes (Charales) in past and present environments: An overview

“…Thus, charophyte cells became convenient models for plant cells in general. The large size of charophyte internode cells makes them easy targets for various kinds of studies in plant cell biology, such as transport processes (Boot et al, 2012), wound healing (Foissner and Wasteneys, 2012), cell wall formation (Proseus and Boyer, 2006), cell elongation (Proseus and Boyer, 2012) or the uptake of persistent organic chemicals into cells (Schneider and Nizzetto, 2012). This is an incomplete list, and numerous studies have been published based on charophytes as models for plant cells in general.…”