1,721,171 research outputs found
Biodiversità
No full textTra le esigenze di tutela ambientale e il diritto all'informazione vi è una stretta interdipendenza: per nessun altro bene o valore come per l'ambiente, la diffusione e la circolazione adeguata delle informazione e delle conoscenze, anche di carattere tecnico, sono indispensabili per una corretta definizione degli oggetti e delle modalità di tutela
CYTOPLASMIC RESERVES IN GENERATIVE AND VEGETATIVE CELLS OF HERMODACTYLUS TUBEROSUS MILL.: CYTOCHEMISTRY, ESI AND EELS ANALYSES
No full textThis study uses cytochemical tests, electron spectroscopic imaging and electron energy loss spectroscopy techniques
to identify and localize the reserves inside the generative cell of Hermodactylus tuberosus pollen. Cytochemical probes
applied to sections observed by light and transmission electron microscopy indicated that the generative cell contains
large osmiophilic bodies probably made of phytic acid rich in P and Ca. The significance of the rich granulations in
generative cells of Hermodactylus pollen is discussed in relation to floral biology and environmental conditions. In
comparison, the vegetative cytoplasm contains (a) lipid droplets formed by unsaturated lipids and related to vacuoles,
(b) lipid bodies with larger dimensions, irregular in shape and very rich in Ca, (c) bodies stained in polysaccharide
tests as well as lipid probes tentatively identified as glycolipid granulations, and (d) small granules very rich in P and
Ca interpreted as phytin granules
The potential role of the archaeobotany in the archaeological sciences: the case study of Neolithic Vitis vinifera L. carpological remains.
No full textMicrosatellite analysis of Latial Olea europaea L. cultivars
No full textOlea europaea L. is one of the oldest domesticated tree species. O. europaea varieties cannot be confused because they are very different in morphology, genetics, and secondary metabolite content. It is important to study and establish the genetic structure of vegetal cultivars to better distinguish them, to solve past misclassification, to preserve plant biodiversity, and to increase their use, diffusion, selection, resistance to adversities, marketing, and scientific applications. Five simple sequence repeat loci (DCA-3, DCA-9, UDO99-9, UDO99-35, and EMO-3) were used to differentiate 39 individuals, representing 13 olive cultivars sampled in Latium (Central Italy). The markers showed a high discrimination power and were able to differentiate 39 alleles. Observed heterozygosity ranged from 0.538 at locus UDO99-9 to 1 at locus UDO99-35, with a mean value of 0.784. DCA loci were the most informative ones. Sample clustering, based on their genetic distance and similarity values, produced a phylogenetic network that has shown a unique major group of cultivars, composed of two sub-branches, and two independent taxa
Characterization of gonidial zone of Cycas revoluta coralloid roots by means of microelectrodes
No full textMicroelectrodes were used for measurements of oxygen, ammonium, potassium and calcium concentrations within gonidial zones of Cycas revoluta coralloid roots. Gonidial zone segments contained an oxygen pressure of 85% with respect to its concentration in the atmosphere. Dissolved ammonium was detected in concentrations between × 10−3 M and 4 × 10−3 M. The highest ammonium concentration was in intermedial segments and it could cause the decrease of nitrogenase activity. Potassium concentration was in the range 5.5–9 × 10−3 M; calcium concentration was 10−6 M in apical and subapical segments, it reached 1–2 × 10−5 M in the intermedial and basal segments. Calcium concentrations could affect heterocyst differentiation, nitrogen fixation and mucilage composition of coralloid roots
Looking for saffron's (Crocus sativus L.) parents
No full textThe authors analyze the archeological, historical, botanical, cytological, geographic, molecular and reproductive biology of saffron and allied species in order to establish its site and parent origin. The authors have studied saffron, Crocus sativus and the diploid species C. cartwrightianus, C. thomasii, C. hadriaticus and compared them with what was previously known from the literature. When saffron originated is still open to dispute. It has been widely known since the pre-Hellenic and Hellenic periods, but it is impossible to detect if was C. sativus or other Crocus species such as C. cartwrightianus. Concerning the site origin the research indicates two possible sites: one in Greece in the Mediterranean area, the other at East in Turkey-Iran-India. In both areas, records and placenames connected with various species of Crocus constitute an important information source for the presence of saffron. Cytological, DNA, and reproductive studies on the allied species of C. sativus such as C. cartwrightianus, C. thomasii, C. hadriaticus, indicate a more likely parent of saffron may be C. cartwrightianus or C. thomasii. Both these species are diploid with a karyotype similar to saffron. In addition, their pollen can fertilize the egg cell of saffron, giving rise to seeds which are viable, germinate and form new corms. Thus Saffron can originate through fertilization of a normal reduced egg cell with an unreduced male gamete of the same Crocus species or by crossing between an egg cell and the male unreduced gamete of another species. The origin of Saffron by allopolyploidy seems more probable considering the recent data on its caryotype and molecular biolog
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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