Work package 1 (WP1) Topic: Cyanobacterial Dormant Forms in an Aquatic environment

1. Work package 1 (WP1) Topic: Cyanobacterial Dormant Forms in an Aquatic environment Objective: Establishment of dormant stage/ Induction of akinetes in cyanobacteria

2. # D4 and # D8 • Basic studies to reveal conditions and mechanisms involved in induction of akinetes formation, dormancy and desiccation: • Nutrient Depletion (P), Light, Temp, O2 (hypoxia), K • Specialized envelopes • Storage of metabolites [carbohydrates, cyanophycin (N)] – enzymes involved, e.g cyanophycine synthase • Tolerance to stress: heat shock proteins/chaperones-function in maintaining structural integrity of biomolecules. • Tryptophan, aspartate, aspargin, phenyl-alanine and serine triggered akinete formation. • Mature akinetes • Respiration and Photosynthetic apparatus (is there pigments production?) • O2 evolution/consumption • Reduced energy production? • To collect adequate material for further genomic, proteomic and metabolomic studies.

3. Research Objective: • To elucidate the molecular mechanism of akinete differentiation in the cyanobacteria Aphanizomenon ovalisporum. • Research plan: • Characterizemorphologicallythe developmental stages from a vegetative cell to a mature akinete. • Test for environmentalvariations that can signal for akinete differentiation, • such as: • K starvation • Different light/dark regimens (circadian clock) • Different light wavelengths (Phytochrome signaling pathway) • Temperature • Mutagenesis screen – looking for none akinetes forming filaments in a K depleted media. • Establish transformation of Aphanizomenon ovalisporum • Test for the expression of candidate genes in akinete cells by PCR, in situ hybridization and fusion proteins (i.e. GFP)

4. Candidate genes in akinetes differentiation: AvaK – Akinete marker gene with an unknown function found in A.variabilis (Zhou and Wolk, 2002) Signal transduction: hetR- A protease showing DNA binding activity. hetR is required for akinete differentiation, and is actively expressed in akinetes (Leganés et al., 1994). devR - Introduction of a plasmid containing wild-type devR into cells of Nostoc sp. strain 29133 results in a stimulation of akinete formation (Campbell et al.,1996).devR is a member of the two-component system, regulatory protein family. Involved in signal transduction, that functions to detect and respond to environmental changes. kdp operon – K+ dependent ATPase Cell wall synthesis: hepA - An ABC transporter required for the normal deposition of akinetes and heterocyst envelope polysaccharide (Leganés, 1994 found in A. variabilis ATCC 29413). Cyanophysin synthesis and degradation: cphA – Cyanophycin synthetase cphB - Cyanophycinase (exopeptidase hydrolyzing cyanophycin)