title: Plasticity in algae.
abstract: Unicellular planktonic algae show considerable developmental plasticity in relation to mean cell size and the fraction of the cell volume occupied by various organelles. Changes in cell size and composition in relation to variations in the supply of light and nutrient solutes have been partially characterized with respect to the signals which regulate the changes, and in terms of the possible significance of the changes in maximizing growth rate under different resource-limited conditions. Less is known of the mechanisms by which the signals lead to the observed phenotypic effects. Multicellular attached macroalgae, whether acellular or multicellular, rhizophytic or haptophytic, have greater scope for phenotypic modification of morphology than do microalgae, in addition to the possibility of biochemical (compositional) changes. In addition to biochemical changes in response to variations in the ratio of availability of various resources (photons, N, P) there are also structural changes; significant here is the increased occurrence of (often colourless) hairs in haptophytes and (probably) of enhanced rhizoid development in rhizophytes. Many of the changes in morphology and physiology of macroalgae in response to changes in photon and nutrient supply have analogies in the behaviour of vascular plants (especially of aquatic vascular plants).
mesh_terms: D000222:Adaptation, Physiological; D002245:Carbon Dioxide / Q000378:metabolism; D002470:Cell Survival; D003300:Copper / Q000378:metabolism; D056890:Eukaryota / Q000166:cytology / Q000502:physiology*; D007501:Iron / Q000378:metabolism; D008938:Mitosis; D010641:Phenotype
chemical_list: D002245:Carbon Dioxide; D003300:Copper; D007501:Iron