Gian Piero Felicini

Ricerche Sui Pigmenti Delle Alghe Rosse. I: Analisi Qualitativa e Quantitativa dei Pigmenti di Pterocladia Capillacea (Gmel.) Born. et Thur. Coltivata in Presenza di Alcune Fonti Minerali di Azoto

Abstract Research on the Red Algae pigments. I: Pigments of « Pterocladia capillacea » cultured with some nitrogenous mineral sources. — In the present paper the effects of different nitrogen sources on the growth and pigments content and composition of P. capillacea are reported. Apical segments of the erect frond showed a variation of the pigments content after one month culture in sea water containing NaN03, NH4Cl, NH4N03. When the segments are kept in limited volumes of sea water not supplemented with a nitrogen source, a decrease of the pigment content, especially phycoerythrin, is observed. 10−3M NH4 inhibits growth and regeneration of the segments, while stimulating the pigment synthesis. Maximum growth was observed when the sea water was supplemented with 10−4 NH4NO3 (initial concentration). Under these conditions the proportions among the pigments studied are almost the same as in freshly harvested plants.

Ricerche Sulla Rigenerazione in Coltura di Pterocladia Capillacea (Gmel.) Born. et Thur. II. Influenza Della Intensita Luminosa Sulla Morfologia del Tallo

Abstract Research on the regeneration in Pterocladia capillacea (Gmel.) Born, et Thur. cultured in vitro. II. Light intensity and development of the erect frond. — The thallus of Pterocladia capillacea consists of two different portions: the erect frond and the creeping axis. The former essentially assimilative and reproductive function while the latter exerts the function of perennation, attachement and vegetative propagation of the alga. As previously shown, both apical and intercalary segments, in culture, grow apically and generate adventitious buds from the cut-surfaces. If the culture are exposed to low light intensities, both the adventitious buds and the preexisting apical meristems give rise to creeping filaments. However, if the light intensity is increased over a threshold level (750–1000 lux) and the light treatment is continued for 12 hours a day, the « distal » tips, both the newly formed adventitious tips and preexistig ones, develop into regular erect fronds. On the contrary, the adventiti...

Autecologia di Ulva rigida: 1. Influenza dell'intensità luminosa e della temperatura sulla produzione di ossigeno

Abstract Autecology of Ulva rigida C. Ag.: 1. Influence of light intensity and temperature on oxygen production. The photosynthetic activity of Ulva rigida, growing in Baris harbour (Adriatic Sea), has been assessed in the laboratory by measuring oxygen evolution as a function of white light intensities. Tests were performed at four temperatures. The data indicate the remarkable amount of O2 released in the environment.

Rapporti Dimensionali Tra Radice Ipocotile e Cotiledoni Nella Germinazione del Seme di Pinus Pinea L.

Abstract Length ratios between root, hypocotyl and cotyledons during the germination of pine seeds. — Germination of Pinus Pinea has been studied from a morphological point of view, recording the change of dimensions of the three parts of the embryo, that is cotyledons, hypocotyl and rootlet. As soon as the embryo starts germinating the three parts above mentioned do not keep the embryonic length ratios, expecially the length ratio cotyledons + hypocotyl/rootlet is upset, as the root elongates very rapidly. During this process the equilibrium point is reached in Pinus Pinea when the radicle protrudes 2–3 mm. from the seed.

Sulla formazione di galle nella rigenerazione di Pterocladia capillacea (Gmel.) Born. et Thur. in coltura

Abstract Galls and regeneration in P. capillacea. – Galls arose from some cultured segments of Pterocladia capillacea in winter trough regeneration from cut-surfaces, especially at the proximal end. Bacteria were always present on the thallus and inside the old galls. They might be the agents of cecidogenesis, even though we never obtained galls in segments treated with these agents. We suggest that gall formation can be induced by bacteria only in winter, when the stimulus of natural differentiation appears to be very low.

Germinazione «In Vitro» di Carpospore di Petroglossum Nicaeense (Duby) Schotter

Abstract In vitro development of carpospores of Petroglossum nicaeense (Duby) Schotter. This paper describes the germination of carpospores of P. nicaeense (Phyllophoraceae) and the development on glass of new tetrasporophytes to the size of 3–4 mm. Different patterns of development are observed: 1) formation of one or two rizoidal filaments which give rise to an adhesive disc; 2) formation of a morula, of limited growth, and of rizoidal filaments which then originate adhesive discs; 3) formation of a morula which originates a single frond, and formation of filaments that do not form adhesive discs. Eventually, the discs give rise to one or more outgrowths that develop into erect fronds. These fronds reach a 4 mm length 3 months after germination.

Società Botanica Italiana, Gruppo di Lavoro per l'Algologia - Lavori presentati alla Riunione Scientifica Annuale a Padova, 20–21 Novembre 1992

Abstract Regeneration in macroalgae: an approach to studies of morphogenesis and correlation growth effects. - Seaweed regeneration is a rather spread survival strategy as a response to wounds which injure the plant integrity. In laboratory, the regeneration ability of algal segments provides suitable means for studying thallus growth and bud differentiation and for hypothesizing mechanisms of hormonal regulation of morphogenesis. Moreover, the most known correlation growth effects, i.e. polarity, apical dominance and apico-basal gradients, can be investigated. In this report the author describes and discuss some experimental results relating to these subjects.

Ricerche sui pigmenti delle alghe rosse. III: influenza della luce sui pigmenti di Petroglossum nicaeense (Duby) Schotter in coltura

Abstract Research on Red Algae pigments. III: Effect of light intensity on pigment formation in Petroglossum nicaeense (Duby) Schotter cultured in vitro. – The results obtained by pigment analysis of Petroglossum nicaeense segments, cultured under various intensities of white and blue light, and their photosynthetic activity are reported. Experiments indicate that there are no basic differences between the plants cultured under different chromatic conditions with respect to their pigment synthesis, while the effect of light intensity variations is evident. The phycoerythrin content is higher in the algae cultured at lower illumination. Moreover, these algae show a complete agreement between this pigment formation and photosynthetic production. With growing light intensities, a rise in carotenoids formation is observed, especially β-carotene, so that the α/β carotene ratio decreases particularly under blue light. Such increase in carotenoid synthesis is regarded as one of the acceptable mechanisms of prote...

Formazioni tumorali in Schottera nicaeensis (Phyllophoraceae)

Abstract Tumour-like formations on cultured Schottera nicaeensis. – Tumour-like growth were occasionally observed on adventitious creeping axes of cultured segments of the frond. They clearly derived from cortical cells; the cause of their formation is still obscure.