Understanding Membrane Function

Abstract

Work on algae has had wide‐ranging impacts on our understanding of membrane function. Work on giant cells of freshwater and marine algae has been very important in defining and characterizing active transport systems for ions and other solutes and for studying other transport processes at the plasmalemma and tonoplast. Such work was particularly important in changing the focus of studies of higher plant membrane transport processes in the 1960s. Recent technical and genetic advances mean that studies formerly confined to large algal cells can now also be performed on higher plants and microalgae, but work on giant cells still makes important contributions. Studies on fucoid embryos continues to make significant contributions to our understanding of the role of transmembrane calcium fluxes in early development. This work has wide‐ranging implications for the development of other organisms.

PHOTOSYNTHETIC UTILIZATION OF INORGANIC CARBON IN THE ECONOMIC BROWN ALGA, HIZIKIA FUSIFORME (SARGASSACEAE) FROM THE SOUTH CHINA SEA1

“…The photosynthetic oxygen evolution rates of many marine macroalgae, however, have been found to be faster than the theoretical maximum rates of CO 2 supply from the uncatalyzed spontaneous dehydration of HCO 3 − in seawater, suggesting the existence of photosynthetic utilization of HCO 3 − (Gao and McKinley 1994, Raven 1997). Although CO 2 can easily pass through biological membranes when there is a gradient in concentration, the ionic HCO 3 − cannot unless actively transported by some facilitating mechanisms (Beer 1994, Axelsson et al 1995, Raven 1997, Raven and Brownlee 2001). Two basic processes have been proposed for HCO 3 − utilization by marine macroalgae.…”

Analysis of Porphyra Membrane Transporters Demonstrates Gene Transfer among Photosynthetic Eukaryotes and Numerous Sodium-Coupled Transport Systems

“…Many vital cellular processes (e.g. osmoregulation, removal or compartmentalization of toxic compounds, and acquisition of nutrients) are dependent on electrochemical gradients of ions such as H + , K + , Na + , and Cl 2 , membrane potential, and/or a pH gradient (Harold, 1986;Raven and Brownlee, 2001;Bisson et al, 2006). Membrane transporters, usually heterogeneous in structure, are integral membrane proteins (that span the lipid bilayers) responsible for moving ions and biomolecules (both organic and inorganic) across the plasma membrane, and between the cytoplasm and organelles (e.g.…”

“…Previous electrophysiological and radioactive tracer studies of algal membrane physiology (Raven and Brownlee, 2001) have revealed families of transporter proteins that are differentially regulated. The biochemistry of these proteins and the gene families that encode them have been examined in green algae and plants (Ward et al, 2009), but much less is known about the function and evolutionary histories of these transporters in Rhodophyta (red algae; for exception, see Barbier et al, 2005).…”