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1.
De novo root formation in thin cell layers of tobacco: changes in free and bound polyamines 总被引:4,自引:0,他引:4
Patrizia Torrigiani Maria Maddalena Altamura Francesca Capitani Donatella Serafini-Fracassini Nello Bagni 《Physiologia plantarum》1989,77(3):294-301
Thin cell layers excised from tobacco ( Nicotiana tabacum L. cv. Samsun) stem internodes, with an appropriate exogenous hormonal balance, were able to form a greater number of roots, and in a larger percentage of the explants (93%) than when they were excised from pedicels (40%). The developmental sequence of root formation and explant growth were followed by histological analysis. Free and bound [trichloroacetic acid (TCA)-soluble and -insoluble] putrescine and spermidine increased in the explants, particularly when root meristemoids appeared. These meristemoids originated in the superficial (day 6 in culture) or deep (days 10–11) layers and inside the newly formed callus (day 25). At those times, TCA-soluble and, to a lesser extent, TCA-insoluble bound putrescine predominated over the other polyamines. Spermine was always present in trace amounts. Polyamines decreased again when root and callus formation was completed (day 30). The involvement of these three classes of polyamines (free, TCA-soluble and -insoluble) in morphogenic processes is discussed. 相似文献
2.
Shawn Doonan Filippo Martini Sebastiana Angelaccio Stefano Pascarella Donatella Barra Francesco Bossa 《Journal of molecular evolution》1986,23(4):328-335
Summary We report here the complete amino acid sequences of the cytosolic and mitochondrial aspartate aminotransferases from horse heart. The two sequences can be aligned so that 48.1% of the amino acid residues are identical. The sequences have been compared with those of the cytosolic isoenzymes from pig and chicken, the mitochondrial isoenzymes from pig, chicken, rat, and human, and the enzyme fromEscherichia coli. The results suggest that the mammalian cytosolic and mitochondrial isoenzymes have evolved at equal and constant rates whereas the isoenzymes from chicken may have evolved somewhat more slowly. Based on the rate of evolution of the mammalian isoenzymes, the geneduplication event that gave rise to cytosolic and mitochondrial aspartate aminotransferases is estimated to have occurred at least 109 years ago. The cytosolic and mitochondrial isoenzymes are equally related to the enzyme fromE. coli; the prokaryotic and eukaryotic enzymes diverged from one another at least 1.3×109 years ago. 相似文献
3.
4.
Donatella Zona Peter M. Lafleur Koen Hufkens Beniamino Gioli Barbara Bailey George Burba Eugénie S. Euskirchen Jennifer D. Watts Kyle A. Arndt Mary Farina John S. Kimball Martin Heimann Mathias Göckede Martijn Pallandt Torben R. Christensen Mikhail Mastepanov Efrén López-Blanco Albertus J. Dolman Roisin Commane Charles E. Miller Josh Hashemi Lars Kutzbach David Holl Julia Boike Christian Wille Torsten Sachs Aram Kalhori Elyn R. Humphreys Oliver Sonnentag Gesa Meyer Gabriel H. Gosselin Philip Marsh Walter C. Oechel 《Global Change Biology》2023,29(5):1267-1281
Long-term atmospheric CO2 concentration records have suggested a reduction in the positive effect of warming on high-latitude carbon uptake since the 1990s. A variety of mechanisms have been proposed to explain the reduced net carbon sink of northern ecosystems with increased air temperature, including water stress on vegetation and increased respiration over recent decades. However, the lack of consistent long-term carbon flux and in situ soil moisture data has severely limited our ability to identify the mechanisms responsible for the recent reduced carbon sink strength. In this study, we used a record of nearly 100 site-years of eddy covariance data from 11 continuous permafrost tundra sites distributed across the circumpolar Arctic to test the temperature (expressed as growing degree days, GDD) responses of gross primary production (GPP), net ecosystem exchange (NEE), and ecosystem respiration (ER) at different periods of the summer (early, peak, and late summer) including dominant tundra vegetation classes (graminoids and mosses, and shrubs). We further tested GPP, NEE, and ER relationships with soil moisture and vapor pressure deficit to identify potential moisture limitations on plant productivity and net carbon exchange. Our results show a decrease in GPP with rising GDD during the peak summer (July) for both vegetation classes, and a significant relationship between the peak summer GPP and soil moisture after statistically controlling for GDD in a partial correlation analysis. These results suggest that tundra ecosystems might not benefit from increased temperature as much as suggested by several terrestrial biosphere models, if decreased soil moisture limits the peak summer plant productivity, reducing the ability of these ecosystems to sequester carbon during the summer. 相似文献
5.
Donatella Marazziti Lionella Palego Chiara Mazzanti Stefano Silvestri Giovanni B. Cassano 《Chronobiology international》1995,12(2):100-105
Our study aimed to investigate the possible presence of seasonal changes in platelet phenolsulfotransferase (ST) in a group of 20 healthy, drug-free subjects of both sexes and between 24 and 37 years of age. Blood samples were taken four times a year in the period immediately following the equinoxes and the solstices. The results showed that both STs underwent seasonal changes: the lowest values were found in autumn and in winter, and the highest in the summer. A positive correlation between the two STs and the length of the photoperiod was observed in winter, whereas in the spring we detected a negative correlation between the TL ST and the photoperiod length. Future studies should clarify whether platelet ST of patients with mood disorders shows a similar seasonality. 相似文献
6.
Summary When injured, the thalli of the coenocytic algaUdotea petiolata undergo a rapid sealing process mainly due to the extrusion of two successive plugs. In the first, external and transitory plug, sulphated polysaccharides are the predominant components. In the second, permanent and internal plug, roundish bodies having a complex polysaccharidic composition are embedded in a fibrillar matrix of still unknown nature. The sulphated sugars were identified and located by means of Alcian Blue staining and X-ray microanalysis. A periodic acid-thiocarbohydrazide-silver proteinate technique proved useful especially in the study of the roundish bodies and in the compositional and structural comparison of the siphon wall with the wound wall. Phosphotungstic acid at low pH was used to evidentiate an extensive plasma membrane activity in the repairing cytoplasm.Supported by a grant of C.N.R. 相似文献
7.
Four 5-amino-4-alkylthio-pyrazoles were synthesized and their antifungal activity was evaluated in vitro in Trichophyton mentagrophytes, Microsporum cookei and Candida albicans. The compounds slightly influenced the growth kinetics of the yeast, but at concentrations ranging from 20 to 40 g/ml completely prevented the mycelial growth of the two dermatophytes cultivated on Sabouraud's agar medium. An electron microscopic study, undertaken by using the most active compound, showed that in C. albicans mitochondria were the only cell targets affected whereas in the dermatophytes cell wall, plasmalemma and the main cytoplasmic organelles were damaged in various degrees. Since the most remarkable alterations were connected with membrane abnormalities, the cytological changes observed were tentatively interpreted as a consequence of the compound intrusion into the lipid bilayer of the membranes, since the drug is lipophilic in nature.Investigations supported by a grant from Consiglio Nazionale delle Ricerche of Italy (Contract No. 79.01871.04) 相似文献
8.
Giuseppe Fossati Andrea Balsari Donatella Taramelli Maria Luisa Sensi Giuseppe Pellegris Maurizio Nava Giorgio Parmiani 《Cancer immunology, immunotherapy : CII》1982,14(2):99-104
Summary Peripheral blood lymphocytes (PBL) of melanoma patients were sensitized in vitro with lymphocytes of a single donor or with a pool of lymphocytes of 5–20 different donors. After 6–7 days, the cytotoxic activity of the sensitized PBL was tested against cultured autologous tumor cells and lymphocytes in a 51Cr-release assay. Tumor lysis was observed in 13 of 16 cases in which patients' PBL (Pt-PBL) were stimulated by a pool of allogeneic lymphocytes and in five out of seven cases when single sensitization was performed. In no case was lysis of autologous normal lymphocytes or blasts seen. Cultivation of Pt-PBL with irradiated autologous tumor cells never led to the induction of lymphocytes cytotoxic to melanoma cells. Lysability by pool-activated autologous Pt-PBL of fresh cryopreserved tumor cells was compared to that of short-term cultured tumor cells, and no significant differences were observed. Cold-target inhibition experiments indicated that the cytotoxicity of Pt-PBL was tumor-restricted since only autologous melanoma cells but not lymphocytes were able to inhibit the reaction. These results indicate that activation of Pt-PBL is necessary in order to elicit or amplify their antitumor activity. 相似文献
9.
Marco Gobbi Michele Baccarani Donatella Ruggero Sante Tura the Italian Cooperative Study Group on Chronic Myeloid Leukemia 《Cancer immunology, immunotherapy : CII》1979,6(1):59-62
Summary Serum immunoglobulin concentration and skin reactivity to at least three recall antigens were determined in 210 patients with chronic myeloid leukemia (CML). Immunoglobulin concentration was normal in the great majority of the patients. Skin tests were negative in 50 of 210 cases (24%). No relationship could be demonstrated between skin reactivity, age, time since diagnosis, WBC, lymphocyte count, and splenectomy. Prior antileukemic therapy was a major factor in determining the response to skin tests.S. Tura (Chairman) and M. Baccarani (Secretary), Cattedra di Ematologia dell'Università e Servizio di Ematologia dell'Ospedale S. Orsola, Bologna; G. de Sandre, G. Perona, G. Cetto, G. Pizzolo, Istituto di Patologia Medica e Cattedra di Ematologia dell'Università, Verona; P. Rambotti, B. Falini, Clinica Medica dell'Università, Perugia; T. Chisesi, G. Capnist, Divisione di Ematologia, Ospedale Civile, Vicenza; A. Cajozzo, P. Citarella, Cattedra di Ematologia dell'Università, Palermo; G. Broccia, Sezione di Ematologia, Ospedale Armando Businco, Cagliari; V. Liso, G. Troccoli, Clinica Medica II dell'Università, Bari; L. Bruzzese, G. Nappi, A. Abbadessa, Clinica Medica (I Facoltà) dell'Università, Napoli; A. Porcellini, C. Delfini, Divisione di Ematologia, Ospedali Riuniti, Pesaro; E. Cacciola, R. Giustolisi, R. Musso, V. Raimondi, Cattedra di Ematologia dell'Università, Catania; G. Torlontano, L. Geraci, Cattedra di Ematologia dell'Università, Chieti, e Divisione di Ematologia, Ospedale Civile, Pescara; F. Mandelli, G. Mariani, B. Monarca, N. Petti, Cattedra di Ematologia dell'Università, Roma; R. di Guglielmo, A. Miliani, Clinica Medica dell'Università, Firenze; C. Bernasconi, M. Lazzarino, G. Castelli, Divisione di Ematologia, Ospedale S. Matteo, Pavia; A. Alberti, S. Magro, Servizio di Ematologia, Ospedale Generale Regionale, Catanzaro; A. Neri, P. Iacopino, Divisione di Ematologia, Ospedali Riuniti, Reggio Calabria; R. Delsignore, M. C. Baroni, Istituto di Patologia Medica dell'Universita, Parma; E. Bajetta, S. Monfardini, Istituto Nazionale per lo Studio e la Cura dei Tumori, Milano; S. Tognella, Istituto Scientifico di Medicina Interna, Cattedra di Clinica Medica 2R, Università, Genova. 相似文献
10.
Transient Photoresponses of a Phototactic Microorganism, Haematococcus Pluvialis, Revealed by Light Scattering
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Franco Angelini Cesare Ascoli Carlo Frediani Donatella Petracchi 《Biophysical journal》1986,50(5):929-936
A new method, using incoherent light scattering, has been developed to measure the flagellar beating frequency of swimming microorganisms. By means of this method, transient changes of flagellar beating frequency in response to white light flashes have been revealed in samples of a phototactic microorganism, Haematococcus pluvialis. An increase of flagellar beating frequency occurs when the flash dose (flash intensity × flash duration) is sufficient. Reciprocity between light intensity and flash duration holds for durations not exceeding 60-80 ms. For lower doses a bimodal distribution of flagellar beating frequency is revealed. No effect is observed for very low flashes or for red stimuli, whereas green light is effective. A detailed analysis of experimental results has allowed us to determine the characteristic time of the effect and follow its evolution. The correlation of this effect with visually observed behavior is discussed and a possible underlying mechanism is suggested. 相似文献