A field, culture and cytological investigation has been made of the life histories of Porphyra gardneri (Smith et Bollenberg) Hawkes, P. nereocystis Anderson and P. thuretii Setchell et Dawson, three superficially similar epiphytic red algae (Bhodophyceae, Bangiales). Porphyra gardneri was found from February through November, but is basically a spring-early summer species, Porphyra nereocystis is an autumn-winter species and P. thuretii is a winter-early spring species. The reported number of host species and geographical distribution is increased for all three species. A light microscope study of spermatogenesis and carposporogenesis was undertaken to characterize the spermatangium and carpogonium and to follow their division sequence. The spermatangium in Porphyra gardneri and probably P. thuretii is formed by the production of a new wall layer around a transformed vegetative cell. In contrast, no new wall layer is formed by P. nereocystis spermatangia, making them difficult to distinguish from vegetative cells. The carpogonium of P. gardneri and P. thuretii is easily recognized because it differentiates bipolar prototrichogynes. In P. nereocystis the carpogonium does not form prctctrichogynes and can only be distinguished from vegetative cells by its elongate, rectangular shape. On the basis of these observations and reports in the literature I suggest that the species of Porphyra can be separated into at least two groups based on their spermatangial and carpogonial morphology; the more advanced group has carpogonia with prototrichogynes and clearly defined spermatangia due to the deposition of a new wall layer, whereas the more primitive group lacks these features. The first division in both spermatogenesis and carposporogenesis is periclinal. This is discussed with respect to the division sequences reported by other workers. The transfer of Porphyrella Gardneri Smith et Hollenberg to Porphyra gardneri is explained on the basis of the observed mode of carpogonium formation and carposporangial division. Of the three species studied, only Porphyra gardneri produces monospores. Under all photoperiod and temperature regimes tested monospores germinated into the foliose phase. At an ultrastructural level monosporogenesis in Porphyra gardneri is characterized by the production of abundant small and large fibrous vesicles. The economic implications of monospore production are discussed. Field observations of Porphyra gardneri suggest that photoperiod is an important factor involved in inducinq the formation of spermatangia and carpogonia. A conchocelis phase is reported for the first time for Porphyra gardneri and Porphyra thuretii. Under all photoperiod and temperature reqimes tested carpospores qerminated into the conchocelis phase. In P. sardneri and P. thuretii short days favoured conchosporanqial branch formation; however, no such photoperiodic effect was observed for P. nereocystis., Although my results were inconclusive, reports in the literature indicate that temperature is a critical factor in conchospore release. Amoeboid movement of conchospores is reported for E°I£J3J£§ thuretii and discussed with respect to the occurrence of this phenomenon in the Rhodophyta generally. The epiphyte-'host' attachment zone of Porphyra gardneri and P. nereocystis was examined with the light microscope. The basal rhizoids of P. gardneri penetrate deep into the medulla of the Laminaria blade, whereas the rhizoids of P. nereocystis make only a superficial penetration of the Nereocystis stipe. The spermatia of Porphyra gardneri and P. nereocystis were examined ultrastructurally and found to have many similarities with Florideophycidae spermatia. The occurrence of fertilization in the life history of Porphyra gardneri is documented with the light and electron microscopes. A diploid chromosome number 2n=8 is reported for the carpospores and vegetative cells of the conchocelis phase P. gardneri. This is the first unequivocal report of sexual reproduction in the genus Porphyra. Suspected spermatia attached to the carpogonia and linked to them via fertilization canals have been observed in P. nereocystis and P. thuretii suggesting that sexual reproduction also occurs in their life histories. Reports of sexual reproduction in other members of the Bangiophycidae are evaluated in light of my observations. / Science, Faculty of / Botany, Department of / Graduate

Thesis (M.Sc. (Zoology & Entomology)) - Rhodes University, 2009

A comparative study was made between two similar red algal endophytes, Audouinella porphyrae (Drew) Garbary and Audouinella vaga (Drew) Garbary, Hansen et Scagel, (Acrochaetiaceae, Acrochaetiales) and their red algal hosts Porphyra spp. and Pterosiphonia bipinnata, respectively. Both endophytes have axial, stellate chloroplasts with a central pyrenoid and reside in their host's cell walls, producing erect portions outside the host that may bear monosporangia. The endophytes were cultured "free" from their hosts and morphological and cytological features of the free-living forms were compared with field material. Although the two endophytes differ significantly in cell dimensions and branching patterns, the free-living forms do not retain these differences. Cell dimensions, branching patterns and developmental patterns are identical in the two free-living forms. Asexual reproduction with regeneration by monospores was observed. Sexual reproduction was not observed in either endophytic or free-living forms of the endophytes. Free-living forms were used for re-infection and cross-infection experiments. Under all experimental conditions, the endophytes showed only epiphytic growth. The hosts seem to have some effect on both of the endophytes. Epiphytes, Audouinella porphyrae and A. vaga were not selective and grew on both hosts, Porphyra torta and Pterosiphonia bipinnata. Both epiphtyes growing on blades of Porphyra tended to branch and have more extensive prostrate portions (3-5 cells) whereas both epiphytes on Pterosiphoni a bipinnata tend not to branch and have only 1-2 cells in the prostrate portions. Ultrastructural studies of both endophytes showed typical florideophycean features. Ultrastructural features of field material of the two endophytes were similar and free-living, cultured endophytes were similar to field material. A large vacuole was observed in sections of the field material of both prostrate and erect portions whereas this was not observed in cultured material. Based on the results of this study it is proposed that the two endophytes are conspecific. Audouinella vaga is referred to synonymy in Audouinella porphyrae (Drew) Garbary, Hansen et Scagel. / Science, Faculty of / Botany, Department of / Graduate

Thesis (M.S.)--University of North Carolina Wilmington, 2006. / Includes bibliographical references (Leaves: 13-15)

A preliminary electrophoretic study on Bangia vermicularis Harvey (Rhodophyta) along the coast of British Columbia was undertaken to determine whether enzyme banding patterns could be used to identify the relatedness of the populations which varied in chromosome number (3, 6 or 4) and life history (asexual or sexual). Material from nineteen sites was tested for seven enzymes: glutamate dehydrogenase (GDH); malate dehydrogenase (MDH); lactate dehydrogenase (LDH); superoxide dismutase (SOD), glucose 6-phosphate dehydrogenase (G6PDH); phosphoglucoisomerase (PGI); and phosphoglucomutase (PGM). Unlike higher plants, some of the banding patterns obtained in Bangia could only be explained if the enzymes SOD, GDH, LDH and PGI are monomers and the enzymes PGM, SOD, GDH, PGI, and G6PDH have only one cellular location. Generally, with the exception of two enzymes, PGI and G6PDH, which were highly polymorphic, only one to three bands were evident. Considerable amounts of variation in the mobility of the isoenzymes were detected between populations independent of chromosome number or sexuality. Contrary to expectations, often populations with three chromosomes or six ' chromosomes had the same number of loci and many of the three chromosome populations had some banding patterns indicative of diploids. Consequently, if there had been a polyploid origin of the six chromosome populations then there must also have been many gene duplications in the three chromosome populations. Alternatively, if the three chromosome populations arose by aneuploid reduction within a six chromosome population then there must also have been gene silencing and/or the formation of null alleles. Populations that were very close geographically differed to a large extent suggesting that there may be little gene flow between populations. The variability between populations could be explained by isolation over long periods of time during which changes could have occurred in the structure and regulation of the enzymes tested. / Science, Faculty of / Botany, Department of / Graduate

A study of the red algal order Gelidiales in British Columbia and northern Washington was conducted. Gelidiales are represented in the study area by four species, Gelidium coulteri, G. purpurascens, G. vagum and Pterocladia caloglossoides, and a key to identify the taxa is provided. Earlier reports of G. crinale, G. pusillum, G. robustum and G. sinicola from British Columbia and northern Washington have been shown to be misidentifications of the other taxa and are excluded from the flora. The occurrence of G. vagum in the British Columbian flora is significant because it appears to have been introduced from the northwest Pacific and now has a disjunct distribution, occurring in Japan and China and on two islands in the Strait of Georgia, British Columbia. Gelidium vagum and the Gulf of California species, G. johnstonii, are considered to be sister species. They share the unique character of monoecy (i.e. unique in the genus) and a morphological resemblance, but differ in several other characters, including arrangement of cortical cells, shape and flattening of tetrasporangial stichidia, shape of stichidial apices and position of the apical initial with respect to the adjacent cortex, presence/absence of an apical furrow and sterile margin in tetrasporangial stichidia and presence/absence of intact third order filaments in mature cystocarps. The life history of Gelidium vagum was completed in culture, only the second Gelidium species for which this has been accomplished. Gelidium vagum has a triphasic Polysiphonia-type life history with isomorphic (monoecious) gametophytes and tetrasporophytes, and carposporophytes growing on gametophytes. The rare occurrence (G. purpurascens, G. coulteri) or absence (Pterocladia caloglossoid.gametophytes in the field and the lack of successful completion of a life history in culture suggests that, whereas these species may occasionally complete a Polysiphonia-type life history in situ, vegetative or apomictic mechanisms are more important in maintaining field populations. Chromosome counts of n = 14 - 15 were made on undivided tetrasporangia of G. vagum. The pattern of spore germination in Gelidium coulteri, G. purpurascens and G. vagum is similar for carpospores and tetraspores. A single germ tube grows from the spore, the entire cytoplasmic contents of the spore evacuate into the germ tube and a wall cuts the germ tube off from the empty spore. The germ tube divides unequally to form a concave and a fusiform cell. The primary attachment rhizoid forms from a derivative of the concave cell and the sporeling apical cell forms from a fusion cell derivative. As apical organization is established, the subapical cell produces two lateral periaxial cells. Carpogonium and carposporophj'te development was followed in Gelidium purpurascens and G. vagum. The functional carpogonium is intercalary. Non-functional carpogonia divide transversely with a concave wall and become sessile and degenerate. The fertilized carpogonium consistenty forms a fusion cell by fusing with adjacent cortical cells. Fusion cell lobes cut off gonimoblast filaments that send out processes that fuse with haploid gametophyte cells of nutritive chains. Carposporangia are produced terminally and laterally by gonimoblast cells and protrude into two locules that have formed as the cortex is pushed away from the plate of second order filaments. Carpospores are released through a single ostiole in each locule. Spermatogenesis, tetrasporogenesis and rhizine morphology were studied ultrastructurally for the first time in Gelidiales. In spermatangial development, apical chloroplasts in the spermatangial mother cell are cut off by a furrow, a mechanism previously not reported in red algae for exclusion of chloroplasts from spermatangia. As the spermatangium matures, spermatangial vacuoles form from the coalescence of vesiculated endoplasmic reticulum and dictyosome-derived vesicles. Spermatangial vacuoles are discharged from the spermatangium just prior to the release of the spermatium. Stages of tetrasporangium development are marked by wall development. Prior to karyokinesis, the young tetrasporangium is dominated by a large nucleus. Following karyokinesis, chloroplasts, starch grains and dictyosomes increase in abundance, a wall layer is deposited, and dictyosomes undergo a series of morphological changes from small and flat, to large and flat producing fibrillar vesicles, to hemispherical and producing cored vesicles. At cytokinesis an electron dense wall layer is deposited around the tetrasporangium and in the cleavage furrow, and cored vesicles secrete a mucilage-like material inside this wall layer. / Science, Faculty of / Botany, Department of / Graduate

Thesis (master's)--Göteborg University, 1999. / Title from PDF t.p. (viewed on Sept. 25, 2007). At head of title: Tjärno Marine Biological Laboratory. Includes bibliographical references (p. 13-14).

Thesis (master's)--Göteborg University, 1999. / Title from PDF t.p. (viewed on Sept. 25, 2007). At head of title: Tjärno Marine Biological Laboratory. Includes bibliographical references (p. 13-14).