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Studies on some British Columbian representatives of the Erythropeltidaceae (Rhodophyceae, Bangiophycidae) McBride, Douglas Leonard

Abstract

Four species of the Erythropeltidaceae [Smithora naiadurn (Anderson) Hollenberg, Erythrotrichia carnea (Dillwyn) J. Agardh, Erythrotrichia boryana (Montange) Berthold and Erythrotrichia pulvinata Gardner] were observed in freshly collected and cultured conditions using light and electron microscopic techniques. The North American Pacific coast distribution of these algae was revised in view of recent collections in British Columbia and Alaska by various workers. A study of their morphologies and life histories revealed new information concerning production of asexual reproductive units (monospores) from the basal attachment organs of E. pulvinata and S. naiadum. At an ultrasfcructural level, many organelles in the vegetative cells of the Erythropeltidaceae examined were found to be similar to those reported in other members of the Rhodophyceae. However, several interesting fine structural characteristics were noted. The cellular shape was remarkably irregular, exhibiting many cytoplasmic protrusions into the cell wall. The single lobed chloroplast possessed a uniform lamellar arrangement and primitive thylakoid stacks or bands. In addition, multivesicular bodies occurred within the cytoplasm and in the cell wall near the plasmalemma. There was no evidence of any type of intercellular connection. The vegetative cell ultrastructurs of E. boryana and E. pulvinata was virtually identical to S. naiadurn but E. carnea exhibited fewer pyrenoid-traversing lamellae and a somewhat different cell wall morphology. Monospore differentiation and release in the Erythropeltidaceae was found to involve a number of specialized subcellular activities. Concomitant with a rounding of the protoplast and reduction in vacuolar area in the vegetative cell, was the accumulation of two products originating from dictyosomes. The possible functions of these products are discussed in relation to spore release and attachment. Additional fine structural features of the developing monospore included an increased number of mitochondria and nuclear pores, a large amount of endoplasmic reticulum and an association between the chloroplast and the nuclear envelope. Upon release the monospore lacked a cell wall and was typified by an extensive accumulation of dictyosome product. In addition, the chloroplast exhibited a "pseudogranum-like" arrangement of thylakoids. The ultrastructural aspects of monospore dsgsneration in culture are also described. Monospore germination in S. naiadum involved several cellular changes including formation of a call wall and a number of vacuoles. A large amount of peripheral endoplasmic reticulum and certain dictyosome populations appeared to play an important role in wall construction while other populations of dictyosomes appeared to be involved in vacuole formation. Of special interest, since it has not been reported in the Rhodophyceae, was the occurrence of a crystalline matrix in some pyrenoids. In addition, the presence of microtubular spindle fibres was demonstrated. The alternate methods of holdfast formation in this alga are also discussed. Sexual reproduction in the Erythropeltidacsae is poorly known. In this study, an ultrastructural description of "spermatial" production in S. naiadum is presented. The dictyosome appeared to play an important role in the maturation of these pale cells. Evidence of the process of gametogenesis and fertilization in E. boryana is also shown. In a concluding discussion, certain ultrastructural and gross morphological information is employed in the construction of a bilateral scheme on the evolution of growth types in the Bangiophycidae.

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