Zoospores of 17 species in 14 genera and sperm of 13 species in 11 genera of Laminariales were studied by electron microscopy. The zoospores are unique in the brown algae in lacking both an eyespot in the single chloroplast and an associated swelling at the base of the shorter, posterior flagellum. Spores of all species possess a distal whiplash on the longer, mastigoneme-bearing anterior flagellum; although it is only seldom preserved for electron microscopy, this appendage may sometimes be as long as the mastigoneme-bearing portion of the flagellum. A microtubular cytoskeleton with connections to the flagellar basal bodies is responsible for maintaining the shape of the zoospore. The sperm are also unique in the brown algae. They are elongate and possess two to three plastids and several mitochondria, but lack an eyespot. Their most distinctive feature is the long posterior flagellum which tapers distaliy as the doublet microtubules of the axoneme are transformed into singlets and then decrease in number. The sperm also bear a distal whiplash on the mastigoneme-bearing anterior flagellum. These laminarialean zoospores and sperm are ultrastructurally distinct from those known in other orders of brown algae, and from Chorda of the Laminariales, which confirms that Chorda is primitive. The longer posterior flageilum of the sperm recalls similar modifications in sperm of other oogamous brown algae, and suggests a common functional significance. / Science, Faculty of / Botany, Department of / Graduate

The development of sporangia and sporangioles is described in the mucoralean genera Choanephora, Blakeslea, Cunninghamella, and Mycotypha. The fine-structure of spore development is examined with transmission and scanning electron microscopy. Cytoplasmic cleavage in multisporous sporangia of Choanephora and Blakeslea involves fusion of cleavage vesicles to form a cleavage apparatus. Similar cleavage events occur in trisporous sporangioles of Blakeslea but the cleavage apparatus is oriented with the three longtitudinal "suture" lines of the sporangiole wall. The outer layer of spore walls is derived from a fibrous coating on the membranes of the cleavage apparatus. The inner wall layer is formed after deposition of the outer layer and is associated with the presence of granular vesicles in the spore cytoplasm. In monosporous sporangioles of Choanephora, Cunninghamella, and Mycotypha no cleavage apparatus is produced. Spores of all genera studied possess a bilayered wall with the outer layer demonstrating much greater electron-density than the inner layer. The relative thicknesses of the two wall layers varies greatly among genera. The outer layer is deposited in ridges and furrows in spores of Choanephora and Blakeslea. The structure of bipolar spore appendages is identical in these two genera. The ultrastructure of spines on sporangial surfaces is described. Spines on sporangioles of Cunninghamella exhibit a fine-structure different from that of Choanephora and Blakeslea. No spines are produced on spore walls of any of the genera studied. The identification of cellular components is examined using plastic-section histochemistry and light-microscopy. The cleavage apparatus initially contains carbohydrate which disappears as the spores mature. Bipolar spore appendages are shown to be composed of carbohydrate, with their bases staining for protein. In all spores, the cytoplasm shows intense staining for protein and weak staining for carbohydrates. Spore walls are difficult to stain with any of the procedures used. Based on the observed comparative ultrastructural development of asexual spores, recommendations and comments are made concerning the taxonomy of the Mucorales. / Science, Faculty of / Botany, Department of / Graduate

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The fine structure of the basidiospores of Pluteus cervinus and Agrocybe acericola is described using TEM, SEM, and light microscopy.The basidiospore wall of Pluteus cervinus is bipartite. No surface ornamentation or germ pore is present. The protoplasm is surrounded by a typical membrane which lacks distinct invaginations. Spores contain much stored lipid, which is centrally located. Spores are uninucleated with the nucleus closely appressed to the cell membrane, located at the base of the spore near the hilar appendage. Mitochondria with few, well-delineated plate-like cristae are present. Endoplasmic reticulum (ER) is scant. Ribosomes occur regularly attached to the ER and outer mitochondrial membrane, as well as being densely packed throughout the cytoplasm. Various sized vacuoles containing an electron dense material are present. Microbody-like organelles are observed, which are probably glyoxysomes, since assays of malate synthase, a maker enzyme of the glyoxylate cycle, are positive.The basidiospore wall of Agrocybe acericola is composed of two distinct layers, both layers are continuous around the spores, at the germ pore the outer wall is very thin and the inner wall becomes thicker. The plasma membrane is appressed to inner wall and lacks invaginations. The protoplasm is densely packed with small granules, probably ribosomes and/or glycogen. Spores contain very little lipid with bipolar distribution. Mitochondria are well-defined and distributed in cytoplasm. Spores are binucleate with the two nuclei lying on a line nearly perpendicular to the long axis of the cell. Various size single membrane-bound vacuoles are widely distributed in the cytoplasm. These vacuoles were shown to contain acid phosphatase indicating lysosomal activity. Microbodies, probably glyoxysomes, are observed. Malate synthase assays are positive indicating the occurrence of the glyoxylate cycle. / Department of Biology

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Spores of Fuligo septica (L.) Weber were studied by light and electron microscopy to determine structural changes during germination. Light microscopic observations indicate that few changes occur prior to protoplast release; however, electron microscopic observations show that a number of changes occur within the protoplast before emergence. An ovoid nucleus becomes irregular and lobed; smooth, cisternal endoplasmic reticulum develops; and concurrent development of dictyosomes and centriole occurs. The dictyosomes and centriole are localized in juxtanuclear sites, and the proximal cylinder of the centriole differentiates into a basal body of a future flagellum. When the spore case ruptures, the inner layer of the wall disappears and the nucleus reverts to its original ovoid form. The protoplast emerges through a wedge-shaped split in the wall and gradually develops into a flagellated cell or, sometimes, a myxamoeba. Simultaneously, contractile and food vacuoles develop, the cisternal endoplasmic reticulum becomes ribosome-coated, and a flagellum develops from the basal body. / Science, Faculty of / Botany, Department of / Graduate

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Typescript. / Thesis (Ph. D.)--University of Hawaii, 1963. / Bibliography: leaves 44-48. / iv, 48 leaves mount. ill., mount. diagrs., tables