Time-resolved detection of three intracellular signals controlling photomorphogenesis in Physarum polycephalum

Abstract

Incompetent plasmodia of Physarum polycephalum exposed to a light pulse sporulated after reaching the competent stage. Fusion of irradiated plasmodia with dark-incubated plasmodia and analysis of sporulation indicated the presence of a morphogenetic signal. It is concluded that a logic AND gate integrates the photoreceptor signal and the competence signal and controls the formation of the morphogenetic signal.

Gene expression kinetics in individual plasmodial cells reveal alternative programs of differential regulation during commitment and differentiation

“…Hence one would expect that the streaming cytoplasm dampens stochasticity of transcription, translation, and of biochemical processes including signaling. The validity of these assumptions is supported by the following experimental findings: (i) plasmodial nuclei are naturally synchronous in proceeding through the cell cycle (Rusch et al 1966;Sachsenmaier et al 1972); (ii) nuclear populations of two plasmodia that are in different phases of the cell cycle self-synchronize immediately after fusion of the two plasmodia (Rusch et al 1966;Sachsenmaier et al 1972); (iii) at threshold stimulus intensity, the decision of a plasmodium to sporulate is taken stochastically and is all-or-none for any given plasmodium (Starostzik & Marwan 1994, 1995a, 1998; (iv) two plasmodia, each carrying a different sporulation-suppressing mutation, one plasmodium stimulated the other not, self-synchronize even when the new gene expression pattern is established in a switch-like manner (Walter et al 2013). We conclude that in a plasmodium, unlike as in a mononucleate eukaryotic cell of typical volume, stochasticity of signaling and gene expression in terms of molecular noise is dampened due to the large cytoplasmic volume of the plasmodium, which may facilitate the system-wide identification of molecular switches and the analysis of bifurcation phenomena related to the control of commitment and differentiation.…”

“…; Sachsenmaier et al . ); (iii) at threshold stimulus intensity, the decision of a plasmodium to sporulate is taken stochastically and is all‐or‐none for any given plasmodium (Starostzik & Marwan , , ); (iv) two plasmodia, each carrying a different sporulation‐suppressing mutation, one plasmodium stimulated the other not, self‐synchronize even when the new gene expression pattern is established in a switch‐like manner (Walter et al . ).…”

A photoreceptor with characteristics of phytochrome triggers sporulation in the true slime mould Physarum polycephalum

“…The albino strain LU897 x LU898 [4] was grown in the dark as microplasmodia in axenic shaken cultures [5]. After 4 days of growth at 26°C the plasmodial mass was harvested and transferred to starvation agar [6] plates (4.5 cm ~) as described [7]. Plasmodia were starved for six days in complete darkness at 22°C to obtain competent specimens.…”

Physarum polycephalum mutants in the photocontrol of sporulation display altered patterns in the correlated expression of developmentally regulated genes

“…Some genes are differentially regulated even at 2 h (Hoffmann et al . ) which is far upstream the point of no return where sporulation of the induced plasmodium can still be prevented by feeding glucose (Starostzik & Marwan , ). This suggests that sensory signal transduction, signal processing at the protein level, and gene regulation at least to some extent are chronologically interwoven.…”