MoYA. 2006. Analysis of polygenic traits of Microcystis aeruginosa (Cyanobacteria) strains by restricted maximum likelihood (REML) procedures: 2. Microcystin net production, photosynthesis and respiration. Phycologia Phycologia 45: 243-248.Phenotypic expression of traits is the result of complex interactions between genotype and environment. A combination of experiments and statistics based on restricted maximum likelihood (REML) procedures was utilised for estimating the proportion of genetic variability in a series of phenotypic characters (microcystin net production, cell size, dark respiration rate, photosynthetic capacity, maximum quantum yield and growth rate), as well as their genetic and nongenetie correlations, measured on 18 Microcystis aeruginosa (Cyanobacteria) strains. Results indicated that the phenotypic variability found in these traits were principally due to genetic differences among strains. Thus, the estimated genetic variability ranged from 50% for dark respiration rate to > 90% in cell size or maximum quantum yield. These results support the conclusions that (1) genetic factors are the main cause of the spatial-temporal heterogeneity observed in quantum yield, respiration and toxin production, and (2) light harvesting and toxin production are not under intense natural selection, both having a low adaptive value. The high variance in toxin production resulting from genetic effects introduces a source of unpredictability in water-supply toxic early warnings. In addition, no significant genetic correlations were found between quantum yield and either maximal growth rate or mean cell diameter.

The effects of UV radiation (UVR) on growth of sporelings of Melobesia membranacea (Esper) Lamouroux, Lithophyllum incrustans Philippi and Mesophyllum lichenoides (Ellis) Lemoine, were investigated by culturing the algae under different doses of photosynthetically active radiation (PAR) only and PAR + UVR. Under natural conditions, the light fields occurring in the habitats of the three species differ substantially. Whereas M. lichenoides and L. incrustans inhabit sunexposed places in the eulittoral and upper part of the sublittoral, M. membranacea grows as an epiphyte in shady crevices in the eulittoral, where irradiance is < 10% of that in sun-exposed places. The relative growth rate (RGR) of sporelings of these non-geniculate coralline algae was affected by the UVR. The extent of harmful UVR effects on growth rate showed a similar increase as a function of the logarithm of the dose in the three species, inferred by a similar slope in all the linear regressions for a given action spectrum. The inhibition of growth under the PAR + UVR showed similar features in the two species of non-geniculate coralline species from sun-exposed places, that is, similar intercepts and slopes in the linear regressions of RGR as a function of the logarithm of the biologically effective dose.

SUMMARY The effects of UV radiation (UVR) on growth of sporelings of Melobesia membranacea (Esper) Lamouroux, Lithophyllum incrustans Philippi and Mesophyllum lichenoides (Ellis) Lemoine, were investigated by culturing the algae under different doses of photosynthetically active radiation (PAR) only and PAR + UVR. Under natural conditions, the light fields occurring in the habitats of the three species differ substantially. Whereas M. lichenoides and L. incrustans inhabit sun‐exposed places in the eulittoral and upper part of the sublittoral, M. membranacea grows as an epiphyte in shady crevices in the eulittoral, where irradiance is < 10% of that in sun‐exposed places. The relative growth rate (RGR) of sporelings of these non‐geniculate coralline algae was affected by the UVR. The extent of harmful UVR effects on growth rate showed a similar increase as a function of the logarithm of the dose in the three species, inferred by a similar slope in all the linear regressions for a given action spectrum. The inhibition of growth under the PAR + UVR showed similar features in the two species of non‐geniculate coralline species from sun‐exposed places, that is, similar intercepts and slopes in the linear regressions of RGR as a function of the logarithm of the biologically effective dose.

The present study analyses a group of students' multimodal productions who are learning a second language within a cooperative learning context using the iPad in a 1:1 format. They turn the act of creating free narrative written texts into a complex communicative process where two modes of representation are employed: written text and still images. These narratives become documents where the language of words and images are interrelated, generating production and communicative processes which should be understood in their double dimension: a) analyse the value the students give to the images in their compositions; and b) taking the narrative as an integrated text, where the systems of representation interact. Examples of experiences using mobile technologies studying the processes of learning generated in school contexts are still scarce. It is important to analyse didactic proposals which incorporate formative tasks in the classroom using these technologies, such as this case.