Phycoerythrins from some Acrochaetium Species

Abstract

THE possibility that the water soluble phycobilin pigments of red algae show physical properties of taxonomic significance at the generic level has been frequently explored. The three main phycoerythrin “types” described are C, B and R-phycoerythrin, based on their plant sources (from the Cyanophyceae, and from the sub-classes Bangiophycidae and Florideophycidae (Rhodophyceae) respectively), and on their absorption spectra. These “types” have been further described as “single”, “two” and “three peak” phycoerythrins, with peaks at 550 mµ, 565 and 550 mµ, and 565, 540 and 496 mµ, respectively¹. It has also been shown in a recent review that the taxonomic implications are not entirely reliable². Thus, in the genus Rhodochorton (order Nemalionales, Florideophycidae), R-phycoerythrin was obtained from R. purpureum (Lightf.) Rosenv. (= R. rothii)³, and B-phycoerythrin from R. floridulum (Dillw.) Nag.⁴. In a recent survey of the phycoerythrins from forty-four species of red algae from Japan, three “types” were again described, a “single peak” phycoerythrin from Compsopogon oishii (Bangiphycidae), with ^λmax at 565 mµ and a “shoulder” at 542 mµ; “two peak” phycoerythrin (peaks at 565 and 495 mµ, with a “shoulder” at 545 mµ) from Bangia and Porphyra (Bangiophycidae) and from Batrachospermum, Chantransia (= Acrochaetium) and Sirodotia (order Nemalionales, Florideophycidae); and “three peak” phycoerythrin (with peaks at 560–570 mµ, 535–545 mµ and 490–500 mµ) extracted from numerous representatives of the Florideophycidae⁵. It seems likely that the pigment “types” described from Japan represent different interpretations of the positions of maxima on the absorption spectra, and such differences can result from both the physiological conditions of the plants and the modes of pigment extraction². Thus the “two peak” phycoerythrin described from Japan was considered to be a form of R-phycoerythrin, and similar to that described for Porphyra from a number of other sources^6–10. It was also suggested, however, that these three pigment “types” might prove of taxonomic significance, with the “single peak” phycoerythrin being typical of primitive red algae, then the plants possessing the “two peaks and shoulder” phycoerythrin being next in order of advance, and the “three peak” phycoerythrin being characteristic of advanced genera.