Distribution of Charasomes in Chara: Re-establishment and Loss in Darkness and Correlation with Banding and Inorganic Carbon Uptake

Abstract

Charasomes are complex structures found in the plasmalemma of the internodal and branchlet cells of the algal genus Chara. They are lost when internodes are stored in the dark for prolonged periods. Prolonged darkness results in the loss of the ability of internodes to form spatially separated bands of low and high pH. Rates for the uptake of inorganic carbon by the internodal cells are also diminished. The ability to band is re-established 8 h after the reintroduction of a light regime. Rates for the uptake of inorganic carbon begin to increase from 24 h. Charasomes reform over the period of 1-15 days after light, beginning as a simple cytoplasmic evagination and progressing toward a typical complex morphology. The re-establishment of charasomes is correlated with an increase in the uptake of inorganic carbon from bicarbonate-containing solutions.

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

“…5 ). Charasomes were never detected in pale cells lacking well-developed chloroplasts consistent with the observation that photosynthesis is required for charasome development (Bisson et al 1991 ; Chau et al 1994 ; Schmoelzer et al 2011 ). Apart from this prerequisite, every cell of the vegetative part of the thallus of Chara australis seems to have the capacity for charasome formation, although to different extent.…”

“…The possibility to stain charasomes in living cells, with the aid of fluorescent plasma membrane and endocytic markers (Klima and Foissner 2008 ; Schmoelzer et al 2011 ), confirmed the earlier electron microscopical studies about the presence of charasomes in the internodal cells of the main axis, the branches, and the branchlets (Fig. 1a ; Bisson et al 1991 ; Chau et al 1994 ; Franceschi and Lucas 1980 and references therein). Under steady state conditions, charasome size and abundance correlated with the pH banding pattern as revealed by the pH indicating dye phenol red (Fig.…”

“…The plasma membrane along the longitudinal cell walls is smooth in the internodal cells of the genera Nitella and Nitellopsis as investigated so far. In the internodal cells of the genus Chara , however, smooth plasma membrane domains alternate with highly complex convoluted membrane areas in light-exposed thalli (Chau et al 1994 ; Franceschi and Lucas 1980 ; Schmoelzer et al 2011 and references therein). The function of these “charasomes” is similar to that of the membrane invaginations found in leaves of submerged water plants (see above).…”

“…The function of these “charasomes” is similar to that of the membrane invaginations found in leaves of submerged water plants (see above). Several studies indicate that they are involved in the photosynthesis-dependent acidification of the environment required for efficient uptake of CO 2 (e.g., Chau et al 1994 ; Price and Badger 1985 ; Price et al 1985 ; Price and Whitecross 1983 ). A recent study confirmed the abundance of H + -ATPases in charasomes and their involvement in the generation of the pH banding pattern at the cell surface under steady state conditions (Schmoelzer et al 2011 ).…”

Calcification and measurements of net proton and oxygen flux reveal subcellular domains in Acetabularia acetabulum

“…The identi®cation and de®nition of these patterns provides us with a starting point from which to analyze the molecular and cellular mechanisms underlying subcellular dierentiation in this alga. Like Chara, which also has been investigated as a system for understanding acid and alkaline domains, photosynthesis and subcellular patterning (Lucas and Smith 1973;Lucas 1983;Chau et al 1994;Plieth et al 1994;Fisahn and Lucas 1995), A. acetabulum is a giant cell with highly active transmembrane ionic behaviors (Bowles and Allen 1986;Gradmann et al 1982;Gradmann 1989), and is capable of withstanding substantial dissection and manipulation (HaÈ mmerling 1936;Mandoli and Hunt 1996;Mandoli 1998b), features which will facilitate our investigations of the behavior of its subcellular regions. Although virtually nothing is known about the mechanisms of subcellular dierentiation in A. acetabulum, these regional dierences could arise through the asymmetric distribution of dierent ion transporters, organelles, photoreceptors and/or other macromolecules.…”