Georg Gärtner

Ein Beitrag zur Kenntnis von Apatococcus lobatus ( Chlorophyta, Chaetophorales, Leptosiroideae )

Comparative investigations on the morphology, life-history, and reproduction of 3 cultivated strains of the atmophytic green algaApatococcus lobatus are presented. Some ultrastructural features are added to the results of earlier investigations, and comments on the systematics and ecology are given. Morphology and cytology of each strain is variable and shows considerable overlapping. The results support the view thatApatococcus consists of a single variable species (A. lobatus) only. For the epiphytic algal associationPleurococcetum vulgaris the more significant termApatococcetum lobati is proposed.

Ein Beitrag zur Kenntnis vonApatococcus lobatus (Chlorophyta, Chaetophorales, Leptosiroideae)

Comparative investigations on the morphology, life-history, and reproduction of 3 cultivated strains of the atmophytic green algaApatococcus lobatus are presented. Some ultrastructural features are added to the results of earlier investigations, and comments on the systematics and ecology are given. Morphology and cytology of each strain is variable and shows considerable overlapping. The results support the view thatApatococcus consists of a single variable species (A. lobatus) only. For the epiphytic algal associationPleurococcetum vulgaris the more significant termApatococcetum lobati is proposed.

Observations in Hemichloris antarctica Tschermak-Woess & Friedmann (Chlorophyceae) and the occurrence of a second Hemichloris species, Hemichloris polyspora n. sp

The chlorococcalean genus Hemichloris is characterized by the possession of two chloroplasts per vegetative cell. The occurrence of a second species of the genus is reported (H. polyspora sp. nov.). Just as H. antarctica it grows cryptoendolithically in sandstone in Southern Victoria Land, Antarctica. In H. antarctica propagation by two autospores prevails over four, whilst in the new species H. polyspora in general four or eight (rarely 16 or 32) autospores are produced and Borodinella-stages do occur typically. Sexuality and zoosporulation do not exist in both species. Internal structures of chloroplasts can be observed by light microscopy more regularly in H. polyspora than in H. antarctica and under various conditions. Investigations of both Hemichloris species by transmission electron microscopy show them to go back to more or less extended assemblages of plastoglobuli. In both species the plastoglobuli are arranged around tubular inflations of thylakoids and apparently attached to the thylakoids. Keeping the cultures for three (even up to seven) months without light makes them survive and causes coming forth of the chloroplast structure throughout.

Investigations of cell morphology and reproduction in Macrochloris radiosa Ettl & Gärtner (Stephano-sphaerinia, Chlorophyta) by light- and WUDQVPLVVLRQ electron microscopy.

Cell division and reproduction of a cultivated strain of Macrochloris radiosa (Stephanosphaerinia clade) were studied by light- and transmission electron microscopy. Multinucleate cells were frequently observed allowing description of the cell structure and details of the reproduction process. Nuclear staining revealed the position of the multiple polymorphic nuclei between the chloroplast lobes. Ultrastructure of coenocytic cells showed no signs of cleavage of the protoplast in the cytoplasm, although basal bodies were already present within the multinucleate cells. In the further course of the reproduction, biflagellate zoospores were developed that retained their flagella during sporulation. Zoospores were subsequently released from the sporangia.

Zur Morphologie and Taxonomie einiger Bodenalgen (Unterfamilie Scotiellocystoideae, Chlorellaceae) aus der Algensarnm1ung in Innsbruck (ASIB, Austria)

Summary Members of the subfamily Scotiellocystoideae FOTT 1976 are often found in terrestrial habitats and characterized by their sculptured cell wall with meridional ribs. Six isolates of the genera Scotiellopsis, Coelastrella and Graesiella from the culture collection of algae at the university of Innsbruck (Austria) have been investigated with light- and electron microscope and new or additional observations on morphology, cytology and reproduction are dealt with. The taxonomic position of each strain is also discussed.

Zur Morphologie und Systematik desTrebouxia-Phycobionten im Thallus vonUsnea longissima (Lecanorales)

In the lichen genusUsnea different species ofTrebouxia-phycobionts as well as different haustorial types are known. The isolated and cultivated phycobiont ofUsnea longissimaAch. was studied by light- and electron microscopy and resembles in cytomorphological details the type ofTrebouxia impressaAhmad. In addition to simple wall-to-wall contacts between the symbiotic components also intraparietal (=intrawall-)haustoria could be observed as the normal interaction type.

Morphological and taxonomical observations on some strains of Chlorosarcina, Chlorosarcinopsis and Planophila (Chlorophyta, Chlorosarcinales), with special reference to vegetative cell division

Summary Two strains of Chlorosarcina stigmatica , one strain of Chlorosarcinopsis minor and one strain of Planophila laetevirens , all isolated from soil, were studied with light microscope and partially with TEM. Special attention was paid on their common feature, the formation of sarcinoid thalli by divisions, which obviously do not accord with the orginal definition of vegetative cell division or desmoschisis. In all investigated strains, the division products (especially when formed as diads) could also be interpreted as autospores. The taxonomic position of the studied strains is still unsure and discussed. The two strains of Chlorosarcina seem to represent the type of Chlorosarcina stigmatica.

Eine einfache Methode zur Darstellung der Struktur der Stärkehüllen von Pyrenoiden bei Grünalgen (Chlorophyta)

Summary Pyrenoids are good taxonomic features in green algae, especially in the small unicellular ones. The structure of their starch sheats is an important character for distinguishing the species in Chlorococcales. There are two types, the normal pyrenoids surrounded by discontinuous starch grains and others surrounded by a continuous starch sheat in form of a hollow sphere. The difference can be demonstrated easier and more distinct by cell squashing than by using iodine solutions. The starch grains of the normal type are after cell squashing loosen and easily separated each from others, wether in the second type the continuous starch sheat remains as an intact hollow sphere.

Мicroscopic investigations (LM, TEM and SEM) and identification of Chlorella isolate R-06/2 from extreme habitat in Bulgaria with a strong biological activity and resistance to environmental stress factors

An extremophilic Chlorella strain R-06/2, isolated from a geothermal spring (+42 °C) in the region of Rupite village (SW Bulgaria), was investigated for species identification. This was done by observation of the cell morphology, reproduction and ultrastructure by light microscopy, scanning electron microscopy and transmission electron microscopy, and by investigation of the cell-wall chemistry. The pyrenoid ultrastructure with a double-layered thylakoid traversing the matrix, the shape of the starch envelope, as well as the cell wall, composed of glucosamine and developed around young autospores, were the features that allowed us to classify the thermophilic strain Chlorella R-06/2 as Chlorella vulgaris Beijerinck 1890.

Chapter 7 – Nonmotile Coccoid and Colonial Green Algae

Abstract Nonmotile unicellular and colonial green algae play an important role in the diversity of freshwater and terrestrial algae of North America. About 133 genera are included in Chapter 7, and, using the light microscope, they are characterized by their cytomorphological features and their modes of reproduction. Drawings from the literature together with color photos and a taxonomic key are supplied to help readers identify the algae. Additional remarks on ecology, distribution, methods of investigation, and a rich list of literature references are provided for the reader, giving further information.