Thesis (M.Phil.)--University of Hong Kong, 1998. / Includes bibliographical references (leaves 146-158) Also available in print.

The chlorophyll and carotenoid pigments obtained from a number of algae were studied in gross acetone extracts. A method proposed by Richards and Thompson was used to calculate the relative proportions of chlorophylls a, b, and c, astacin and non-astacin carotenoids present. Complete absorption spectra from 350 mμ to 700 mμ were obtained for several algae, chiefly those belonging to the Chlorophyta. It was found that the presence of chlorophyll b could be detected as a small irregularity in the spectral curve at 460 mμ. The xanthophyll pigments of twenty-eight different species of algae were investigated. Chromatographic columns were used to isolate the individual pigments. A mixture of magnesia (Micron Brand) and Hyflo Super Cel was used as the adsorbent. Ethylene chloride was used as the solvent. Fourteen different xanthophyll pigments were found. Twenty two species of Green Algae were investigated in an attempt to show that the presence or absence of certain pigments may indicate phylogenetic relationships. Individual xanthophyll pigments appear to be of little phylogenetic significance. Groups of these pigments, however, seem to be more significant. Fairly uniform and closely related groups such as the Zygnematales and the Ulvales contain certain characteristic groups of pigments. Less uniform groups such as the Volvocales and the Cladophorales appear to lack characteristic groups of pigments. The results agree fairly well with modern phylogenetic relationships, based on the morphology and methods of reproduction. More extensive work with more genera and species is needed before generalizations at the ordinal level can be made. / Science, Faculty of / Botany, Department of / Graduate

Pseudendoclonium was established in 1900 by N. Wille to include a crust-forming green microalga occurring near the high water line on jetties in Drobak, Norway. Ordinal and familial affiliation of the genus have remained uncertain due to a lack of distinguishing morphological characteristics and because molecular phylogenetic data have not been generated for the type species. Ribosomal SSU rDNA sequence data for Pseudendoclonium submarinum, the type species, are presented. Phylogenetic analysis of these data place Pseudendoclonium within the Ulvales. SSU rDNA sequence data from three additional species, Pseudendoclonium basiliense, Pseudendoclonium akinetum and Pseudendoclonium fucicola are included in the analyses and clearly support the hypothesis that Pseudendoclonium is polyphyletic. Based on the sequence data, P. submarinum and P. fucicola share ulvalean lineage, but these algae are not congeneric and P. fucicola must be removed from Pseudendoclonium. Sequence data support the classification of P. basiliense and P. akinetum as distinct species of a single genus. The close affiliation of these two species with Ulothrix and other Ulotrichalean genera, however, reveals their ordinal separation from P. submarinum. P. basiliense and P. akinetum must also be removed from Pseudendoclonium and require generic reassignment within the Ulotrichales.

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A culture collection of clonal, axenic cultures of 35 Arthrospira strains and five strains, which were duplicate subcultures of the original isolates, was established. In addition, eight morphological mutants were isolated from cultures of these strains. All strains are different from those belonging to the genus Spirulina as concluded from TEM and PyMS studies. All Arthrospira strains, duplicates and different morphotypes were screened for variation in morphological, ultrastructural, physiological and biochemical characters for taxonomic purposes. Special emphasis was put on the analysis of factors which influence the morphology of the trichome helix, as this is the feature most characteristic forArthrospira strains. For example, the orientation of coiling was found to be influenced by genetic drift or the growth temperature, but can also be reversed by mechanical impact. Studies were also made on the ability to utilize sugars for growth. None of the strains grew on sucrose, but many grew on glucose and/or fructose. Growth in the presence of sucrose under photoheterotrophic conditions required an adaptation process, though sucrose is not being utilized for growth. Analysis of fatty acid composition of all strains revealed quantitative differences between strains, most markedly in the unsaturated fatty acid fraction. Repeat experiments showed the same results each time, indicating the value of this approach for identification purposes. Similarly, lectin-binding to cell surface structures proved to be a useful approach for differentiation between strains. Analysis of the whole cell composition by pyrolysis mass spectrometry (PyMS) did not confirm the clusters based on other phenotypic characters, but showed that there is a high similarity between duplicate strains or different morphotypes derived from the same stock. Numerical analysis of the data for 28 characters resolved the helical strains in two phenotypic clusters which show a high correlation to the two molecular clusters based on ARDRA of the ITS of the same set of strains. The helical trichome morphology of the strains showed the highest correlation to either of the clusters. Comparison of species descriptions and morphological characters of the strains, as determined in the presented work, indicate, that phenotypic cluster I is composed of Arthrospira maxima, A. fusiformis and A. indica, while A. platensis forms phenotypic cluster II

This thesis is a study of the evolution and development of the flagellate green algae. The first part is a comparative study of the evolution of body size, multicellularity and segregated soma. The allometry of morphological characters, development, life history and the life cycle are also considered. The second part is an experimental test of the potential role of mutation as a determinant of the course of evolution. Mutation is directional for all the characters studied. The variances and covariances created by mutation are compared to those of 30 species of Volvocaceae; the correspondence between the two depends upon the characted examined. In the third part, the growth of germ cells grown with and without a soma is compared. The response to nutrient concentration of cells grown with an intact soma is steeper than that of cells grown without a soma. This result demonstrates a physiological advantage of soma in Volvox, attributable to a division of labour between 'source' and 'sink'.

Genomic sequence data from the three domains of life have revealed a remarkable diversity of genome architectures. The relative contributions of adaptive versus non-adaptive processes in shaping this diversity are poorly understood and hotly debated. This thesis investigates the evolution of genome architecture in the Chloroplastida (i.e., green algae and land plants), with a particular focus on the mitochondrial and plastid genomes of chlamydomonadalean algae (Chlorophyceae, Chlorophyta). Much of the work presented here describes unprecedented extremes in: i) genome compactness (i.e., the fraction of noncoding DNA in a genome), ii) genome conformation (e.g., circular vs. linear vs. linear fragmented genomes), iii) intron and repeat content; and iv) nucleotide-composition landscape (e.g., GC-rich vs. AT-rich genomes). These data are then combined with intra-population nucleotide diversity data to explore the degree to which non-adaptive forces, such as random genetic drift and mutation rate, have shaped the organelle and nuclear genomes of the Chloroplastida. The major conclusions from this dissertation are that chlamydomonadalean algae show a much greater variation in organelle genome architecture than previously thought — this group boasts some of the most unusual mitochondrial and plastid genomes from all eukaryotes — and that the majority of this variation can be explained in non-adaptive terms.

Thesis (Ph. D.)--California State University, Fullerton, 1985. / Includes bibliographical references (leaves 59-64).