Sulla variabilità cromatica dei fiori nelle specie di Crocus L. delle Alpi sudorientali italiane

Abstract

Chromatic variability of tepals in species of Crocus L. of South-eastern Alps.—The anthocyanidins causing the color of tepals of some species of Crocus L. in the Italian South-eastern Alps were determined and characterized. The genus Crocus of this region is represented by four entities: C. napolitanus Mord. & Loisel., C. albiflorus Kit. ex Schult., C. reticulatus Stev. ex Adam. and C. weldenii Hoppe ex Baker.

The distribution of anthocyanidins in the four entities confirms the existence of a systematic distance among the species belonging to Reticulati and the species belonging to Anulati. Two anthocyanidins, i.e. delphynidin and petunidin, which are always present in other entities, have not been found in C. weldenii; this species is characterized by the only presence of malvidine.

The anthocyanidins assume therefore in this case a chemotaxonomic meaning.     

Le « Pedicularis » della serie « Foliosae » Maxim. della Flora italiana

Abstract

The « Pedicularis » of the series « Foliosae » Maxim, in the Italian Flora. – The paper deals with the badly known distribution of Pedicularis foliosa L., P. hoermanniana K. Maly and P. hacquetii Graf (ser. Foliosae Maxim.) both in Europe and in Italy. The illyrian P. hoermanniana occurs also in central Italy, being therefore a typical periadriatic entity. It completely substitutes the two others species in the Italian peninsula.     

Cellulase involvement in the abscission of peach and pepper leaves is affected by salicylic acid

Phenolic compounds appear to be involved in a number of regulatoryactivities in plants. During the last decade an increasing amountof evidence has brought to light the role played by salicylicacid in a number of physiological processes. Particularly interestingis the inhibitory effect of salicylic acid on ethylene biosynthesis,which might make this natural plant compound a useful tool forcontrolling some of the responses usually promoted by ethylene.Our data show that salicylic acid is actually able to reduceleaf abscission in both peach and pepper plants. Biochemicalanalyses have revealed that the enzyme usually involved in thisphenomenon (cellulase, EC 3.2.1.4 [EC] .) does not increase followingactivation of leaf abscission in plants treated with salicylicacid. In contrast, control plants show a marked increase inthe levels of both enzyme activity and cellulase protein. Flushingplants with exogenous ethylene in the presence of salicylicacid induces an increase in cellulase expression which, however,does not equal the level induced in plants without salicylicacid. Key words: Cellulase, leaf abscission, peach, pepper, salicylic acid     

Elucidation of the structure of constrained bicyclopeptides in solution by two-dimensional cross-relaxation spectroscopy: Amatoxin analogues

The evaluation of peptide structures in solution is made feasible by the combined use of two-dimensional NMR in the laboratory (NOESY) and rotating frames (ROESY), and by the use of molecular dynamics calculations. The present paper describes how both the NMR method and molecular dynamics calculations were applied to very rigid synthetic bicyclic peptides that are analogues of natural amatoxins. The NMR theory, which allows the estimate of interatomic distances between interacting nuclei, is briefly discussed. The experimental data were compared with those of known solid-state structures. Three amatoxin analogues have been examined. Of these, one is biologically active (S-deoxo γ[R] OH-Ile³-amaninamide) and its structure in the solid state has recently been worked out. The second and third analogues (S-deoxo-Ile³ -Ala⁵-amaninamide and S-deoxo-D -Ile³ -amaninamide, respectively) are inactive and their solid-state structures are unknown. The data presented confirm the authors' previous hypothesis that lack of biological activity of S-deoxo-Ile³-Ala⁵- amaninamide is due to the masking of the tryptophan ring by the methyl group of L -Ala and not to massive conformational changes of the analogue.     

Indomethacin prevents the long-lasting inhibitory effect of aspirin on human platelet cyclo-oxygenase activity

Aspirin and indomethacin do interact with the same site on cyclo-oxygenase. This suggestion is based on in vitro studies on ram seminal vesicles and in vivo drug interaction studies on rat platelets. The purpose of the present study was to ascertain whether the same interaction also occurred after administration of both drugs to human volunteers. Platelet aggregation induced by sodium arachidonate or by collagen, and formation of platelet MDA and TxB2 were measured before, two and 48 hours after ingestion of either indomethacin (50 mg) or aspirin (500 mg) or of both drugs (30 minutes apart). While the inhibitory effect of indomethacin on these parameters was short lasting, that of aspirin persisted for at least 48 hours. However, when both drugs were given concurrently, the long-lasting effect of aspirin was no longer detectable. Since competition at levels other than platelets was unlikely, this study indicates that indomethacin and aspirin inhibit human platelet cyclo-oxygenase by the same basic mechanism. Acetylation of the enzyme appears to be a secondary mechanism which makes the inhibitory effect of aspirin persistent.     

Mycosporine-like amino acids protect the copepod Boeckella titicacae (Harding) against high levels of solar UVR

Studies were conducted in Lake Titicaca, Bolivia (16°S,69°W, 3810 m a.s.l.) to determine the effects of solar ultravioletradiation (UVR; 280–400 nm) and the protective role ofmycosporine-like amino acids (MAAs) in the calanoid copepodBoeckella titicacae (Harding). Zooplankton samples were takenfrom two different radiation environments: Lake Titicaca anda tank with running lake water, which was covered with layersof neutral-density screen for over a year, receiving ~10% ofincident radiation. Samples collected from the lake had significantlyhigher amounts of MAAs compared with those from the tank. Duringshort-term experiments (6–8 h incubations; six radiationtreatments using sharp cut-off Schott filters), significantlyhigher mortality was observed in B. titicacae from the tankthan from the lake. The higher sensitivity of B. titicacae containinglow amounts of MAAs (compared with specimens collected fromthe lake) was assessed through the determination of biologicalweighting functions (BWFs). A 3-day-long experiment performedwith specimens collected from the lake indicated an increasein mortality as a function of UVR exposure, reaching valuesas high as 70% at the end of day 3 for those individuals thatreceived full radiation compared with <10% for those thatreceived only photosynthetically active radiation (PAR; 400–700nm). Concomitantly, a reduction in the concentration of UV-absorbingcompounds as a function of UVR dose and decreasing wavelengthwas determined. The relatively high UVR dose threshold for mortality(~300 kJ m^–2), as well as a comparison with related species,demonstrated the high resistance of B. titicacae to UVR. Ourresults indicate that this resistance is provided by the presenceof protective compounds, i.e. MAAs, which were efficiently bioaccumulatedthrough the diet.     

Growth Factor–dependent Activation of αvβ3 Integrin in Normal Epithelial Cells: Implications for Tumor Invasion

Integrin activation is a multifaceted phenomenon leading to increased affinity and avidity for matrix ligands. To investigate whether cytokines produced during stromal infiltration of carcinoma cells activate nonfunctional epithelial integrins, a cellular system of human thyroid clones derived from normal glands (HTU-5) and papillary carcinomas (HTU-34) was employed. In HTU-5 cells, αvβ3 integrin was diffused all over the membrane, disconnected from the cytoskeleton, and unable to mediate adhesion. Conversely, in HTU-34 cells, αvβ3 was clustered at focal contacts (FCs) and mediated firm attachment and spreading. αvβ3 recruitment at FCs and ligand-binding activity, essentially identical to those of HTU-34, occurred in HTU-5 cells upon treatment with hepatocyte growth factor/scatter factor (HGF/SF). The HTU-34 clone secreted HGF/SF and its receptor was constitutively tyrosine phosphorylated suggesting an autocrine loop responsible for αvβ3 activated state. Antibody-mediated inhibition of HGF/SF function in HTU-34 cells disrupted αvβ3 enrichment at FCs and impaired adhesion. Accordingly, activation of αvβ3 in normal cells was produced by HTU-34 conditioned medium on the basis of its content of HGF/SF. These results provide the first example of a growth factor–driven integrin activation mechanism in normal epithelial cells and uncover the importance of cytokine-based autocrine loops for the physiological control of integrin activation.     

Studio sulla colorazione da antocianidine in alcune specie della flora italiana

Abstract

Flower colour and anthocyanidin pigments in some species of the Italian flora.—The anthocyanidin pigments, cyanidin and peonidin, of Corydalis cava and C. solida have been identified. The chromatic variation of C. cava is due to quantitative variation of the pigments. Only quantitative differences exist between the two species C. cava and C. solida. The pigments are absent in the white flowers.

The pigments of Pulmonaria visianii in all flower ages are delphinidin, petunidin and malvidin. The blueing of flowers with ageing depends on pH; being 5.6 for red, 6.0 for purple and 6.7 for blue flowers.     

Bacterial Endophytic Communities in the Grapevine Depend on Pest Management

Microbial plant endophytes are receiving ever-increasing attention as a result of compelling evidence regarding functional interaction with the host plant. Microbial communities in plants were recently reported to be influenced by numerous environmental and anthropogenic factors, including soil and pest management. In this study we used automated ribosomal intergenic spacer analysis (ARISA) fingerprinting and pyrosequencing of 16S rDNA to assess the effect of organic production and integrated pest management (IPM) on bacterial endophytic communities in two widespread grapevines cultivars (Merlot and Chardonnay). High levels of the dominant Ralstonia, Burkholderia and Pseudomonas genera were detected in all the samples We found differences in the composition of endophytic communities in grapevines cultivated using organic production and IPM. Operational taxonomic units (OTUs) assigned to the Mesorhizobium, Caulobacter and Staphylococcus genera were relatively more abundant in plants from organic vineyards, while Ralstonia, Burkholderia and Stenotrophomonas were more abundant in grapevines from IPM vineyards. Minor differences in bacterial endophytic communities were also found in the grapevines of the two cultivars.