The process of photoactivation has been studied in dark grown cells of Chlamydomonas reinhardtii. A mutant, FUD 39, lacking the Cl--concentrating 23-kDa psbP protein of photosystem II was found to have a decreased capability to perform photoactivation. The yield of the process never reached wild type level, and contrary to the wild type, it was highly dependent on the intensity of the activating light, with a very narrow optimum around 1 microE m-2 s-1. The different behavior in the mutant can be explained by a requirement for a longer dark period, between the two photoacts, during the photoactivation. This is proposed to reflect the decreased Cl- affinity in the mutant. Photoactivation in the mutant was also found to be very sensitive to competing photoinhibitory processes. The inhibition was located to the donor side of photosystem II and affected the photoactivation capability before electron transfer from Tyrz was inhibited. We propose an extended model for photoactivation in which an intermediate that is sensitive to photoinhibition is formed if Cl- is not functionally bound to the manganese cluster.

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Protochlorophyll forms in roots of dark-grown plants. Protochlorophyll was found in roots of dark-grown piants of seven species investigated. It was identified by absorbance and fluorescence spectra of acetone and ether extracts. Chlorophyll was aiso found in roots of one pea species. The concentration of protochlorophyll was usually highest in young root tips and decreased upwards along the roots. The maxima of the in vivo absorbance spectra of the species studied varied hetween 634 and 638 nm. Low temperature in vivo fiuorescencc emission spectra had two maxima, one at ca 633 and the other at ca 642 nm, when the wavelengths of the excitation light were 440 and 460 nm, respectively. In vivo fluorescence excitation spectra displayed a shift of the excitation maximum from 438 to 445 nm, when emission varied from 620 to 647.5 nm. Deconvolutlon of these three types of spectra into Gaussian components made it possible to identify two spectral forms of protochlorophyll: protochlorophyH,,^,:, and protochlorophylljj,_Mi.

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Chlorophyll formation capacity along the seedling of bean (Phaseolus vulgaris L. cv. Brede zonder draad) was investigated. After 7 days of irradiation a gradient was formed, where the primary leaf contained ca 300 times more chlorophyll per gram fresh weight than the lower hypocotyl section and ca 20 times more than the epicotyl. Similar chlorophyll gradients but at lower levels were seen when the seedlings were first placed in darkness for 7 days and then irradiated for 1, 2 or 7 days. Ultrastructural investigation of seedlings grown for 7 days in darkness and then irradiated for 24 h revealed a more developed inner membrane system with grana stacks in plastids of cells in the uppermost hypocotyl section compared to plastids of cells in lower hypocoty] sections. The higher up on the seedling the more the ratio increased of protochlorophyll(ide) emitting at 657 nm to short‐wavelength protochlorophyll(ide). After flash irradiation of the different sections, fluorescence emission spectra with maxima at 680 and 690 nm, respectively, were observed, indicating the formation of short‐ and long wavelength chlorophyll(ide) forms. The lower the ratio of protochlorophyll(ide) emitting at 657 nm to the short‐wavelength protochlorophyll(ide), the less long‐wavelength chlorophyll(ide) was formed after irradiation. However, after continuous irradiation long‐wavelength chlorophyll(ide) was formed. In dark grown roots, where only short‐wavelength protochlorophyll forms were present, it was not possible to transform protochlorophyll to chlorophyll by flash irradiation. Possible explanations for this phenomenon are discussed.

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Throughout the world, the educational system is expected to deal with issues regarding sustainability and to promote pro-environmental behaviours and attitudes. This study investigates attitudes towards nature and the environment among 1,109 teachers and student teachers in Sweden and France, using the 2 factor Model of Environmental Values (2-MEV). The results imply that in both Sweden and France, teachers and student teachers hold a prevailingly ecocentric attitude, as opposed to an anthropocentric attitude, which possibly indicates a predominantly positive approach towards the environment and environmental education. Comparisons between the countries show, however, that the Swedish teachers and student teachers hold a more anthropocentric attitude than the teachers and student teachers in the French sample.