Cytochemical Ultrastructure of Peltigera Canina: some Features Related to its symbiosis

Abstract

Modified techniques have made it possible to investigate structures and inclusions in the lichen Peltigera canina with the primary object of following their development from the growing edge of the thallus to fully differentiated areas towards the centre. At about 60 lira from the growing edge of the thallus an area of cell division occurs. All the fungal material originates in this zone, whose cells have meristematic features. In the phycobiont, polyglucoside granules are specifically differentiated by Thiery's test. Phycobilisomes are identified by a triple staining technique. Cyanophycin granules are clearly stained with phosphotungstic acid at a low pH and this corroborates the protein composition of these granules. Incubation in a lead nitrate medium made it possible to follow the ontogeny of the polyphosphate granules. In the mycobiont, the plasmalemma is strongly invaginated in hyphae close to bluegreen algal cells and may initiate ' mesosome-like ' structures possibly involved in absorption of algal carbohydrates. Two types of vacuoles are demonstrated. The first one [diaminobenzidine (DAB) + and Gomori-] corresponds to common vacuoles which develop in cortical and medullar hyphae. The second one (DAB-and Gomori +) is only found in the hyphae of the algal layer and corresponds to autophagic vacuoles. They are involved in the system ' mesosome-like structure/autophagic vacuole/primary lysosome ', which could participate in the absorption of exogenous carbohydrates. The concentric bodies appear in great numbers in the zone of maximum cell division. As their number diminishes from this zone towards the differentiated parts of the thallus, it is concluded that they are passively distributed in all differentiated hyphae of the thallus. They consist of an electron-transparent core, from which a radiating system of unit membranes arises. Unit membranes are impregnated with a more or less electrondense, granular substance which forms concentric layers surrounding the central core.

The Nostoc‐Nephroma symbiosis: localization, distribution pattern and levels of key proteins involved in nitrogen and carbon metabolism of the cyanobiont

“…However, the structural appearance of heterocysts was similar to that in cyanobionts of Peltigera spp. (Englund 1977, Bergman and Hallbom 1982, Boissiere 1982. We subjected ultrathin sections of younger and older cephalodia from N, arcticum to polyclonal antisera against nitrogenase, GS, PE and Rubisco.…”

Manganese as a site factor for epiphytic lichens

“…Electron-dense deposits in hyphae of Mn-treated soredia probably contained Mn, as the mycobiont of H. physodes is known to accumulate Mn intracellularly in polyphosphate granules and other deposits (HAUCK et al 2002d. Mesosome-like structures are thought to be involved in the metabolite transfer between the two partners of the lichen symbiosis, especially by storing metabolites received from the photobiont in the mycobiont (PEVELING 1972, BOISSIÈRE 1982. Thus, their absence from all Mn-treated samples indicates that already relatively low Mn concentrations may severely impair the metabolite transfer to the mycobiont.…”

“…Concentric bodies are specific organelles of fungi, primarily of lichenized species (GRIFFITH & GREENWOOD 1972), and have been assumed to be involved in membrane repair (AHMADJIAN 1993), e.g., enabling the fungus efficiently to repair membranes after desiccation (GALUN et al 1974, BOISSIÈRE 1982, PEVELING et al 1985. This assumption is supported by the absence of concentric bodies from Hydrothyria venosa, a permanently submerged aquatic lichen (JACOBS & AHMADJIAN 1973).…”

Role of the Cytoskeletal Actomyosin Complex in the Motility of Cyanobacteria and Fungal Spores

“…On the other hand, blebbing and the release of small vesicles by the cyanobacterial outer membrane have been observed in distantly related symbiotic and nonsymbiotic cyanobacteria such as Nostoc, the cyanobiont of Peltigera spp. [44]. Blebs are spherical membrane protrusions produced by contractions of the actomyosin cortex often considered to be a hallmark of apoptosis.…”