The Heterocysts of the Blue‐green Alga Nostochopsis Lobatus: Effects of Cultural Conditions

Abstract

SUMMARYThe branched filaments of Nostochopsis lobatus form infrequent intercalary heterocysts in the main trichome while the short lateral branches (1-4 celled) characteristically produce only a terminal heterocyst when the alga is grown in a medium devoid of combined nitrogen. In the presence of ammonium nitrogen, intercalary heterocysts are not formed but the lateral heterocysts enlarge to assume a balloon-like appearance; they undergo division in situ and liberate 3-5-called germlings. These germlings grow and produce similar heterocysts and the cycle is repeated until growth ceases. Heterocysts are produced at the terminal ends of the long lateral branches during the later stages of growth in ammonium medium; they are not formed, in this position, in cultures grown in nitrogen-free medium. The possible role of lateral heterocysts in controlling growth and development of long laterals is discussed.

Morphological description and ecology of some rare macroalgae in south-central Spanish rivers (Castilla-La Mancha Region)

“…In both cases N. lobata was found in small temporary streams running over siliceous metamorphic rocks, located at low altitude and living in warm and oligotrophic waters, and it was collected in summer. In terms of habitat, we found N. lobata growing epiphytic (young) and free floating (senescent) even though it has been reported in different habitats: lakes (Tiwari, 1978;El Saied, 2007), running waters (Frémy & Feldmann, 1934;Palmer, 1941;Pandey & Pandey, 2008), thermal springs (Yoneda, 1939), epiphytic (Sarma & Chapman, 1975), attached to rocks (Hoffmann, 1990;Peerapornpisal, 2006), free floating (Wood, 1872), on moist soils Aziz, 2008), and on humid walls ) among others. However, the most extreme habitat where N. lobata has been found is probably as cryptoendolithic in an arid climate (Weber & al., 1996).…”

“…1930Alcaraz & al. -1932Desikachary, 1959;Tiwari, 1978;Peerapornpisal & al., 2006). In Europe there are only third records from flowing warm waters: Banyuls-sur-Mer (France) (Frémy & Feldmann, 1934), Corsica (France) (Hoffmann, 1990), and L'Aquila (Italy) (Del Grosso, 1977).…”