Phormidium uncinatum

Fig. 4. Photophobic action spectrum (solid linej and low temperature absorption spectrum (dashed line) of Phormidium uncinatum. Abscissa wavelength in nm Ordinates relative response and absorbance respectively (after Nultsch88), Hader39), modified)...

Fig. 5. Effect of o-phenanthroline on photophobic response (open circles) and photokinesis (closed circles) of Phormidium uncinatum. Abscissa o-phenanthroline concentration in mol Ordinate response in % of the uninhibited control (after Nultsch and Jeeji-Bai104))...

Phototactic action spectra of Phormidium autumnale and Phormidium uncinatum, measured by Nultsch86>89), show prominent maxima in the absorption range of C-phycoerythrin and smaller, but distinct, peaks in the absorption range of C-phyco-cyanin. Red light absorbed by chlorophyll a is not active, while in the blue range absorbedby the Soret band, the action spectrum shows aminimum(Fig. 6). Nultsch87) concluded that biliproteins are photoreceptors of phototaxis, but independently of the photosynthetic electron transport and phosphorylation. 

Fig. 6. Phototactic action spectrum (circles and heavy solid line) of Phormidium uncinatum. For comparison the absorption spectra of C-phycoerythrin (fine solid line) and myxoxanthophyll (dashed-dotted line) are drawn. Abscissa wavelength in nm Ordinates phototactic reaction value Rt in relative units and absorbance respectively (modified after Nultsch89))...

Hader, D.-P. Untersuchungen zur Photo-phobotaxis von Phormidium uncinatum. Thesis, Marburg 1973... 

Phormidium ambiguum Phormidiumfrigidum Phormidium uncinatum Plectonema boryanum... 

Similarly, chemotactic behaviour of bacteria is controlled by Ca . Mobile bacteria swim towards certain chemicals and away from others. Such bacteria can swim smoothly in a straight line or tumble, which results in random changes in direction. When heading towards repellents bacteria tumble more frequently to increase the probability of swimming away. Influx of Ca causes tumbling. Such behaviour has been found for Bacillus subtilis but apparently not for E. co/i. Calcium accelerates the swimming speed of Chlamydomonas reinhardii and regulates reverse motion in phototactically active Phormidium uncinatum and Halobacterium halobium. Phototaxis in H. halobium involves a methylation-demethylation process which is calcium dependent. Attractant stimuli raise the level of methylation of membrane proteins, while repellent stimuli cause demethylation and the enhanced opportunity for reversal of direction. Ca " " deactivates the methyl transferase and activates a methyl esterase. ... 

Phenyl phosphatosulfate hydrolysis in catalysis, 444 Phormidium uncinatum activity calcium, 595 Phosphatases activation... 

Hader D-P and Poff KL (1982) Dependence of the photophobic response of the blue-green alga, Phormidium uncinatum, on cations. Arch. Microbiol 132, 345-348. 

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