Studies on morphogenesis in a blue-green alga. I. Effect of inorganic nitrogen sources on developmental morphology of Anabaena doliolum

Abstract

Spore germination, heterocyst production, hormogone formation, and sporulation are the morphogenetic stages in the developmental cycle of Anabaena doliolum Bharadwaja. In basal medium sporulation is simultaneous while heterocyst formation is sequential. Nitrate, nitrite, and ammonium nitrogen inhibit sporulation and heterocyst formation. The degree of inhibition depends on the concentration and source of inorganic nitrogen. Nitrate and nitrite induce lysis which is concentration dependent and circumscribed by time, i.e., up to a certain stage the lytic events are preventable by transfer to basal medium, but beyond this stage they become inevitable and complete lysis occurs even in the absence of nitrate or nitrite. The sequential differentiation and spatial relations of heterocysts in a growing filament are characteristic of each nitrogen source and indicative of the polarity involved in the gradient of heterocyst formation.

Akinetes of the Cyanobacterium Nostoc PCC 7524: Macromolecular Composition, Structure and Control of Differentiation

“…Sodium chloride (Canabaeus, 1929), glutamate (Demeter, 1956) and glucuronate (Wolk, 1969, which stimulated akinete differentiation in other cyanobacteria, had no effect on Nostoc 7524 and, unlike Cylindrospermum licheniforme (Fischer & Wolk, 1976), akinete-containing cultures of Nostoc 7524 did not appear to produce an extracellular compound which induced akinete differentiation in younger cultures. Although nitrogenase activity declined at the end of exponential growth, nitrogen limitation did not appear to be involved in the induction of differentiation since a continued supply of nitrogen was required and, in contrast to A. doliolum (Singh & Srivastava, 1968), the process was not inhibited by exogenous supplies of combined nitrogen.…”

Potential triggers of akinete differentiation in Nodularia spumigena (Cyanobacteriaceae) isolated from Australia

“…Similarly, Ahuja et al (2008) observed a doubling in the akinete frequency in Anabaena torulosa with addition of nitrate to N-free cultures and Li et al (1997) observed no akinete development in Anabaena muscosa, A. crassa and A. spiroides under N-free conditions. In contrast, Singh & Srivastava (1968) and Fay et al (1984) reported an increase in akinete frequency when A. doliolum and A. circinalis were cultured in nitrate-free media and Suikkanen et al (2010) reported that akinete sedimentation in N. spumigena during a field bloom in the Baltic Sea was related to a complete depletion of dissolved inorganic nitrogen. In studies by van Dok & Hart (1996), Sutherland et al (1979) and Rother & Fay (1979), nitrate had no affect on akinete differentiation in Anabaena circinalis, Nostoc PCC7524, and Aphanizomenon flosaquae, respectively.…”

AKINETE FORMATION IN PLANKTONIC ANABAENA SPP. (CYANOBACTEFUA) BY TREATMENT WITH LOW TEMPERATURE1

“…Herdman 1987). Although the depletion or addition of nutrients induced or inhibited akinete formation, the same compound often had opposite effects in different organisms or even in the same organism (Wolk 1965, Singh and Srivastava 1968, Tyagi 1974, Rother and Fay 1977, Simon 1977, Sinclair and Whitton 1977, Sutherland et al 1979, Nichols et al 1982, Fay et al 1984, van Dok and Hart 1996. There is contrasting evidence with respect to akinete formation in two different planktonic Anabaena strains, designated as the same species but having different authorities, A. circinalis (Kutz.)…”