Studies of sporogenesis in the rhodophyta

THE OOGONIA OF MACROALGA UNDARIA PINNATIFIDA ARE ALKALINE-PHOSPHATASE POSITIVE AND CONTAIN GERMINAL BODY-LIKE STRUCTURES(1)

It was observed that in the female gametophyte of Undaria pinnatifida (Harv.) Suringar (Phaeophyta, Laminariales) gametangial initials and maturing oogonia demonstrated different levels of alkaline-phosphatase activity (APA). The oogonia exhibited a higher level of APA than in its initials. Electron-dense granular ovoid structures ∼0.5-0.6 μm were present in the cytoplasm of oogonia. These inclusions were not membrane bound and do not appear to be associated with any particular organelles. The number of the inclusions was 1 to 2 in a single section of the cell. In essential details, the specific APA and subcellular germinal body-like structure of the developing female gamete in U. pinnatifida were very similar to those in metazoan oocytes.

The annulate lamellae--from obscurity to spotlight

This review aims to provide a comprehensive and in-depth survey of a cell organelle, the annulate lamellae, that is widely distributed and especially prevalent in both female and male sex cells as well as tumor and cancer cells. The organelle is also present in many somatic cells and plant cells. Emphasis is placed on the contributions that electron microscopy and associated experimental approaches have made in providing information about the distribution, ultrastructure, morphogenesis and relationships of annulate lamellae to other cellular organelles, especially the nuclear envelope and endoplasmic reticulum, as well as cell product. An increasing number of experimental manipulations have recently been shown to alter, either increase or decrease, the amount of annulate lamellae and these studies are explored in depth. Information about the origin and morphogenesis of annulate lamellae in different cells is summarized and extensive coverage is given to several hypotheses about possible annulate lamellae function. A detailed bibliography provides a thorough compilation of research dealing with annulate lamellae. A major goal of this extensive review is to generate increased awareness of, and interest in, this cell organelle for students and investigators of the cell who, by bringing current techniques in cell and molecular biology to bear, might focus and intensify studies on the function of an organelle whose precise role in the cell is presently enigmatic.

The red algal-higher fungi phylogenetic link: the last ten years

The review of the red algal theory for ancestry of Ascomycetes and Basidiomycetes published 10 years ago by the author is updated. Criticisms are answered and new data are discussed. The production of choline sulfate, lenthionine and lanosol are added to the biochemical similarities between red algae and higher fungi. Distribution of polyols is shown to be in favour of the origin of higher fungi from parasitic red algae. As predicted, NADP-linked glutamate dehydrogenase has been found in red algae, and additional reports of chitin in various algae have been published. New supporting data come from the ultrastructure of red algae: mitosis outside the Ceramiales and ultrastructure of vegetative cells and tetrasporocysts of Corallinaceae. On the other hand, the discovery of proplastids in Holmsella makes it less fungus-like. However, no decisive argument has yet been produced for or against the theory. Further light should be expected from protein and nucleic acid sequences. Promising partial sequences of cytochrome c have indeed been published for red algae but the published 5 S ribosomal RNA sequences have not proven relevant to the problem. Sequences of the slower-evolving large rRNA and cytochrome c of red algae could provide convincing evidence and are urgently needed.

Fine-structural studies of the gametes and embryo of Fucus vesiculosus L. (Phaeophyta). III. Cytokinesis and the multicellular embryo

Condensation of the chromosomes during the first cell division following fertilization of the brown alga Fucus vesiculosus L. is accompanied by the almost complete disappearance of the nuclear envelope. Golgi vesicles and other small vesicles appear within the spindle, which has paired centrioles at each end. A large amount of rough endoplasmic reticulum is in the surrounding cytoplasm during mitosis, and many vesicles at the spindle margin are encircled by stacks of endoplasmic reticulum. Annulate lamellae are observed during mitosis. The envelope which initially reforms around the chromatin in telophase has unevenly spaced nuclear pores. Cytokinesis results primarily by vesicle addition to a centripetal furrow. Mitochondria and chloroplasts concentrate around the partition site, possibly in association with microfilaments. Fibrillar material is added rapidly to the space between the daughter cells from vesicle discharge of both cells and seems to spread into the older cell wall surrounding the embryo. The rhizoid daughter cell contains numerous mitochondria and hypertrophied Golgi bodies whose vesicles increasingly pack the cell. The thallus daughter cell is packed with a variety of vesicles, and the nucleus is surrounded by many dilated cisternae of rough endoplasmic reticulum. By the four-cell stage, chloroplasts of the rhizoid cells have weakly staining lamellae, while chloroplasts of the thallus cells are actively dividing with deeply staining lamellae.