Aromatic and aliphatic mono- and bis-nitroxides: A study on their radical scavenging abilities

Nitroxide radicals are an emerging class of interesting compounds with versatile antioxidant and radioprotective properties. All literature studies have so far concentrated on compounds bearing only one nitroxide function. Here, we now investigate and compare the radical scavenging behaviour and antioxidant activity of aromatic indolinonic and aliphatic piperidine bis-nitroxides, i.e compounds bearing two nitroxide functions. Their corresponding mono-derivatives were also studied for comparison. Radical scavenging activity was investigated using EPR and UV–Vis spectroscopy by following spectral changes in acetonitrile of the nitroxides in the presence of alkyl and peroxyl radicals generated, respectively, under anoxic or aerobic conditions from thermal decomposition of AMVN [2,2′-azobis(2,4-di-methylvaleronitrile)]. Antioxidant activity of the nitroxides was evaluated by monitoring conjugated dienes (CD) formation during methyl linoleate micelles peroxidation and by measuring carbonyl content in oxidized bovine serum albumin (BSA). The results show that: (a) each nitroxide moiety in bis-nitroxides scavenges radicals independent of each other; (b) aliphatic nitroxides do not scavenge peroxyl radicals, at least under the experimental conditions used here, whereas indolinonic aromatic ones do: their stoichiometric number is 1.14 and 2.17, respectively, for mono- and bis-derivatives; (c) bis-nitroxides are roughly twice more efficient at inhibiting lipid peroxidation compared to their corresponding mono-derivatives. Although this study provides only comparative information on the relative radical-scavenging abilities of mono- and bis-nitroxides, it helps in understanding further the interesting reactivity of these compounds especially with regards to peroxyl radicals where many controversies in the literature exist.     

Frammenti cotiledonari di Aesculus hippocastanum L. coltivati in vitro. Primi dati sul comportamento dell'amido e dell'escina

Abstract

Fragments of Aesculus hippocastanum L. cotyledons grown in vitro. First results about starch and aescin characteristic features.—Cotyledon fragments of Aesculus hippocastanum grown in vitro in different media have been able to form callus and roots. The starch granules in the new cells are compound in structure and morphologically different from the simple cotyledon granules, whereas they are similar to the granules of the other parts of the plant in toto. Moreover, the callus has no aescin even though it originates from the cotyledor tissues.     

A geostatistical model to describe root vitality and ectomycorrhization in Norway spruce

Abstract

The spatial distribution of vital root tips and ectomycorrhizal (ECM) communities in forest soils is characterized by patchiness at a microscale level, mostly related to the distribution patterns of biotic and abiotic factors. A geostatistical model was applied to verify if spatial analyses could be useful in identifying an appropriate sampling method to study root tip vitality, ectomycorrhization and the ECM community. Root samples were collected from two high mountain Norway spruce forests (Trentino province, Italy) following a geometrical design. Laboratory microscopic and geostatistical ordinary kriging analyses were used to map tip vitality and ectomycorrhization degree, ECM richness and distribution grouped in “exploration types” (amount of emanating hyphae or presence and differentiation of rhizomorphs). Spatial gradients of the examined features existed at plant level, associated to the up-downslope direction (root tip vitality and ectomycorrhization, ECM richness) and distance from the stem base (ECM exploration types). The effectiveness of the geostatistical model used demonstrates that a geometrical sampling design, associated to spatial mapping techniques, can be useful in research where the tree, and not the forest, is the subject (mycological and phytopathological studies).     

Reflexions sur nos cultures d'antheres de plantes cultivées

Abstract

Considerations about our anther cultures of cultivated plants. – One of the main activities performed at the Casaccia Nuclear Centre, in the framework of a contract between CNEN and the European Communities, centers on the induction of haploid plants by anther culture and the subsequent chromosome doubling in order to obtain completely homozygous diploid plants. In tobacco, it is now possible to obtain haploid plants from any cultivar; we perform in vitro culture of internodes from which homozygous diploid plants are regenerated, taking advantage of natural phenomenon of endopolyploidy. In order to try to generalize this method of producing haploid plants in other plant species, we are studying the mechanism involved in haploid embryogenesis which occurs in vitro in the microspores. Datura, Nicotiana and Atropa are among the genera in which a direct embryogenesis from the microspore is observed; it is interesting to note that all three genera belong to the family Solanaceae and are very rich in alkaloids. In almost all the other cases of in vitro induction of haploids, microspores produce calli from which plantlets can be differentiated, but this way of plant regeneration is less interesting because only few plantlets are obtained and it is not sure that each haploid comes from a single microspore. We examined the factors which could influence the transformation of microspores into embryoids in tobacco, namely: the developmental stage of microspore, the degeneration of tapaetal cells, the genotype of microspore, the composition of cultural media, the physiological conditions of the plant from which the anthers were taken. From a practical point of view, it would be desirable to have informations on methods giving a maximum number of haploid plants from one embryogenic anther and the greatest number of embryogenic anthers from the cultured anthers. Our recent experiments on anther culture in liquid shaken medium have yielded good results (about 7,000 embryoids from 25 embryogenic anthers). Further, we are conducting several experiments in order to synchronize the development of the microspores in the anthers; to this end, we analyse the effect of cold treatment, ionizing radiation and gravity force. Experiments are being performed with other cultivated species, beside tobacco, in order to solve some problems of plant breeding more easily and quickly through haploidy. With the aim of introducing, in cultivated tomato, some desirable characters from the wild species, Lycopersicum peruvianum, (self-incompatibility, disease resistance, simultaneous flowering), we have obtained the interspecific hybrid through in vitro culture of young embryos. Haploid production from this hybrid could allow to quickly obtain various genetic recombinations from these two species. For this purpose we are carrying out anther cultures as well as single microspore cultures. In rice, strawberry and L. peruvianum, several diploid and tetraploid plantlets were obtained from our anther cultures. Work is in progress to ascertain the mode of their origin.     

A phytosociological analysis of abandoned terraced olive grove shrublands in the Tyrrhenian district of Central Italy

ABSTRACT

A phytosociological study of the shrubland communities which colonise abandoned terraced olive groves in the Tyrrhenian district of Central Italy is presented here. The vegetational analysis was carried out using the Braun Blanquet phytosociological approach. Two main types of shrubland communities characterising distinct environmental conditions occur within abandoned terraced olive groves. On the one hand, there are those scrub types which tend to occupy the central part of the terrace; on the other hand, there are the scrubs types which develop along the stone walls bordering the terrace. Different phytosociological associations, sub-associations, and variants ranging from Pistacio-Rhamnetalia alaternii to Prunetalia spinosae are recognised and described. In the warm dry areas, both Myrto-Lentiscetum and Rhamno-Euphorbietum dendroidis occur. Also, a new Oleo-Ceratonion sub-association (Myrto-Lentiscetum spartietosum junceii) is presented here for the first time. In the inner zones of the study area, a range of aspects characterising a new Pruno-Rubion ulmifolii community type (Roso-Rubetum ulmifolii ass. nova) are identified.     

Laser Microdissection (LM): Applications to plant materials

Abstract

In recent years, Laser Microdissection (LM), which has been widely used in animal biology, has been adapted to plant tissues. This short paper focuses on some technical aspects concerning plant sample preparation for LM technology, with particular attention to the application of gene expression and proteomics studies. Examples derived from the use of different LM methods are reported and their applications to plant–microbe interactions are explored.     

Nuove ricerche sulla coltura in vitro di Aucuba japonica Thunb

Abstract

New researches on the culture « in vitro » of Aucuba japonica Thunb, – Caulinar fragments grown in vitro in nutrient media solidified with agar are compared with fragments grown on a filter paper support on unshaken liquid media. Tissue cultures of Aucuba are established putting down caulinar fragments just taken from the plant with isolated callus; subcultures are obtained more easily in July. We have observed that during the months of March or April, caulinar fragments, taken from the plant at various months of the year, of different ages and cultivated on various media, unexpectedly produce many roots.     

Biochemical investigations of the nuclear proteins during the transition of root meristems from quiescent to proliferating state in Pisum sativum

Abstract

The electrophoretic analysis of nuclear proteins extracted from root meristems at different times of germination puts in evidence the variations of content of specific proteins. Several nuclear proteins are phosphorylated by endogenous protein kinase and often the maximum rate of phosphorylation it has been observed in proteins present in the nucleus at low concentrations. Moreover also the phosphorylation rate of specific proteins changes at different times of germination. It is interesting the fact that both variations of concentration and phosphorylation in nuclear proteins occurr at the time when root meristems leave the quiescence to enter a proliferating state. We suggest that these variations play a role in this physiological event.