Action spectrum for sporulation and photoavoidance in the plasmodium of Physarum polycephalum, as modified differentially by temperature and starvation. 1996

T Nakagaki, and S Umemura, and Y Kakiuchi, and T Ueda
Graduate School of Human Informatics, Nagoya University, Japan. nakagaki@info.human.nagoya-u.ac.jp

The plasmodium of the myxomycete Physarum polycephalum sporulates in bright natural environments, suggesting a relationship between photobehavior and sporulation. Thus, the action spectra for two light-dependent phenomena as well as the effects of other environmental conditions have been studied. Sporulation like photo-avoidance responded to UVC (near 270 nm) and near IR (near 750 nm) in addition to the well-documented UVA (near 350 nm) and blue (near 460 nm) regions. Sporulation and photoavoidance had similar sensitivities in the shorter wavelengths, while the former was about 100 times more sensitive in near IR. The plasmodium moved away from light in a wide spectral range. Starvation and high temperature at 31 degrees C (25 degrees C in standard conditions) reduced photoavoidance to UVA and to blue light, respectively. A high fluence rate of UVC suppressed the rhythmic contraction of the plasmodium, and the action spectrum peaked at 270 nm. These results indicate that the Physarum plasmodium may stay at brighter places not by positive phototaxis but by weakening the negative phototaxis to sunlight or by other possible taxes such as hydrotaxis. There may be at least four different photo-systems in the plasmodium.

UI MeSH Term Description Entries
D007259 Infrared Rays That portion of the electromagnetic spectrum usually sensed as heat. Infrared wavelengths are longer than those of visible light, extending into the microwave frequencies. They are used therapeutically as heat, and also to warm food in restaurants. Heat Waves,Heat Wave,Infrared Ray,Ray, Infrared,Rays, Infrared,Wave, Heat,Waves, Heat
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D013056 Spectrophotometry, Ultraviolet Determination of the spectra of ultraviolet absorption by specific molecules in gases or liquids, for example Cl2, SO2, NO2, CS2, ozone, mercury vapor, and various unsaturated compounds. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed) Ultraviolet Spectrophotometry
D013217 Starvation Lengthy and continuous deprivation of food. (Stedman, 25th ed)
D013696 Temperature The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms. Temperatures
D014466 Ultraviolet Rays That portion of the electromagnetic spectrum immediately below the visible range and extending into the x-ray frequencies. The longer wavelengths (near-UV or biotic or vital rays) are necessary for the endogenous synthesis of vitamin D and are also called antirachitic rays; the shorter, ionizing wavelengths (far-UV or abiotic or extravital rays) are viricidal, bactericidal, mutagenic, and carcinogenic and are used as disinfectants. Actinic Rays,Black Light, Ultraviolet,UV Light,UV Radiation,Ultra-Violet Rays,Ultraviolet Light,Ultraviolet Radiation,Actinic Ray,Light, UV,Light, Ultraviolet,Radiation, UV,Radiation, Ultraviolet,Ray, Actinic,Ray, Ultra-Violet,Ray, Ultraviolet,Ultra Violet Rays,Ultra-Violet Ray,Ultraviolet Black Light,Ultraviolet Black Lights,Ultraviolet Radiations,Ultraviolet Ray
D016839 Physarum polycephalum A protozoan, previously also considered a fungus. Characteristics include sporangia that are stalked and multilobed. It is widely used in biomedical research. Physarum polycephalums,polycephalum, Physarum
D018462 Photobiology The branch of biology dealing with the effect of light on organisms.
D019265 Spectroscopy, Near-Infrared A noninvasive technique that uses the differential absorption properties of hemoglobin and myoglobin to evaluate tissue oxygenation and indirectly can measure regional hemodynamics and blood flow. Near-infrared light (NIR) can propagate through tissues and at particular wavelengths is differentially absorbed by oxygenated vs. deoxygenated forms of hemoglobin and myoglobin. Illumination of intact tissue with NIR allows qualitative assessment of changes in the tissue concentration of these molecules. The analysis is also used to determine body composition. NIR Spectroscopy,Spectrometry, Near-Infrared,NIR Spectroscopies,Near-Infrared Spectrometries,Near-Infrared Spectrometry,Near-Infrared Spectroscopies,Near-Infrared Spectroscopy,Spectrometries, Near-Infrared,Spectrometry, Near Infrared,Spectroscopies, NIR,Spectroscopies, Near-Infrared,Spectroscopy, NIR,Spectroscopy, Near Infrared

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