Phycomyces sporangiophores

Fig. 19. Hypothetical orientation of the SO - SI transition dipoles (blue band) of the bluelight photoreceptor in the Phycomyces sporangiophore as concluded from polarized light experiments96). Horizontally polarized light is about 20% more effective than vertically polarized light, as sketched...

Another enzyme involved in cell wall growth is chitinase which could be involved in the regulation of growth rate. Its properties in Phycomyces sporangiophores have been described (Cohen, 1974a) but light effects on the activity of its enzyme have not yet been reported. 

Stochastic Growth Patterns Generated by Phycomyces Sporangiophores... 

Galland, P. and Lipson, E.D., Light physiology of Phycomyces sporangiophores, in Phycomyces, Cerdd-Olmedo, E. and Lipson, E.D., Cold Spring Harbor Laboratory, Cold Spring Harbor, NY,... 

Curry, G.M. and Gruen, H.E., Action spectra for the positive and negative phototropism of phycomyces sporangiophores, Proc. Natl Acad. Scl USA, 45, 797,1959. 

Galland, R, Phototropism of the Phycomyces sporangiophore a comparison with higher plants, Photochem. Photobiol, 52, 233,1990. 

The gravity sensor is unknown in Phycomyces. Statoliths have not been detected. Any particle with a density different from that of the average density of the cytoplasm could be a candidate, e.g., mitochondria, lipid droplets, nuclei or crystals. The work of Dennison (1961) has clearly shown that the gravity sensor must be inside the cell because the response is independent of the density of the medium outside the sporangiophore. 

Cosgrove, D. 1., Ortega, 1. K. E. Shropshire, W., Jr. (1987). Pressure probe study of the water relations of Phycomyces blakesleeanus sporangiophores. Biophysical Journal, 51, 413-24. 

Cowan, M. C., Lewis, B. G. Thain, J. F. (1972). Uptake of potassium by the developing sporangiophore of Phycomyces blakesleeanus. Transactions of the British Mycological Society, 58, 113-26. 

Such a model describes an underdamped oscillatory behavior with a sinusoidal period of 11 minutes and damping coefficient of 0.44. This period of oscillation corresponds to the "hunting swings of the sporangiophore therefore, it appears that our model accounts for the gross mechanical behavior of Phycomyces and its interaction with our measurement system. 

The sporangiosphores of Phycomyces produce ethylene, and ethylene enhances elongation of the sporangiophore and interferes with its normal avoidance or autochemotropic response (Russo et al. 1977). Russo (1977) postulated... 

In the transparent sporangiophore of Phycomyces, the irradiance difference is caused by its lens property that leads to focusing of unilateral hght in a bright band on the distal side. The elevated irradiance in the focal band is responsible for the elevated growth rate at the distal side, causing positive phototropism. Lens effects that are relevant for phototropism also occur in other hyaline cells, such as in chloronemata of ferns and mosses. 

Grolig, R, Eibel, R, Schimek, C., Schapat, T., Dennison, D.S., and Galland, R, Interaction between gravitropism and phototropism in sporangiophores of Phycomyces, Plant Physiol, 123, 765, 2000. lino, M., Tarui, Y., and Uematsu, C., Gravitropism of maize and rice coleoptiles dependence on the stimulation angle. Plant Cell Environ., 19,1160,1996. 

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